/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2007 by Janne Karhu.
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Contributor(s): none yet.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file blender/blenkernel/intern/particle.c
 *  \ingroup bke
 */


#include <stdlib.h>
#include <math.h>
#include <string.h>

#include "MEM_guardedalloc.h"

#include "DNA_curve_types.h"
#include "DNA_group_types.h"
#include "DNA_key_types.h"
#include "DNA_material_types.h"
#include "DNA_mesh_types.h"
#include "DNA_meshdata_types.h"
#include "DNA_particle_types.h"
#include "DNA_smoke_types.h"
#include "DNA_scene_types.h"
#include "DNA_dynamicpaint_types.h"

#include "BLI_blenlib.h"
#include "BLI_noise.h"
#include "BLI_math.h"
#include "BLI_utildefines.h"
#include "BLI_kdtree.h"
#include "BLI_rand.h"
#include "BLI_threads.h"
#include "BLI_linklist.h"

#include "BLF_translation.h"

#include "BKE_anim.h"
#include "BKE_animsys.h"

#include "BKE_boids.h"
#include "BKE_cloth.h"
#include "BKE_effect.h"
#include "BKE_global.h"
#include "BKE_group.h"
#include "BKE_main.h"
#include "BKE_lattice.h"

#include "BKE_displist.h"
#include "BKE_particle.h"
#include "BKE_material.h"
#include "BKE_key.h"
#include "BKE_library.h"
#include "BKE_depsgraph.h"
#include "BKE_modifier.h"
#include "BKE_mesh.h"
#include "BKE_cdderivedmesh.h"
#include "BKE_pointcache.h"
#include "BKE_scene.h"
#include "BKE_deform.h"

#include "RE_render_ext.h"

unsigned int PSYS_FRAND_SEED_OFFSET[PSYS_FRAND_COUNT];
unsigned int PSYS_FRAND_SEED_MULTIPLIER[PSYS_FRAND_COUNT];
float PSYS_FRAND_BASE[PSYS_FRAND_COUNT];

void psys_init_rng(void)
{
	int i;
	BLI_srandom(5831); /* arbitrary */
	for (i = 0; i < PSYS_FRAND_COUNT; ++i) {
		PSYS_FRAND_BASE[i] = BLI_frand();
		PSYS_FRAND_SEED_OFFSET[i] = (unsigned int)BLI_rand();
		PSYS_FRAND_SEED_MULTIPLIER[i] = (unsigned int)BLI_rand();
	}
}

static void get_child_modifier_parameters(ParticleSettings *part, ParticleThreadContext *ctx,
                                          ChildParticle *cpa, short cpa_from, int cpa_num, float *cpa_fuv, float *orco, ParticleTexture *ptex);
static void do_child_modifiers(ParticleSimulationData *sim,
                               ParticleTexture *ptex, ParticleKey *par, float *par_rot, ChildParticle *cpa,
                               float *orco, float mat[4][4], ParticleKey *state, float t);

/* few helpers for countall etc. */
int count_particles(ParticleSystem *psys)
{
	ParticleSettings *part = psys->part;
	PARTICLE_P;
	int tot = 0;

	LOOP_SHOWN_PARTICLES {
		if (pa->alive == PARS_UNBORN && (part->flag & PART_UNBORN) == 0) {}
		else if (pa->alive == PARS_DEAD && (part->flag & PART_DIED) == 0) {}
		else tot++;
	}
	return tot;
}
int count_particles_mod(ParticleSystem *psys, int totgr, int cur)
{
	ParticleSettings *part = psys->part;
	PARTICLE_P;
	int tot = 0;

	LOOP_SHOWN_PARTICLES {
		if (pa->alive == PARS_UNBORN && (part->flag & PART_UNBORN) == 0) {}
		else if (pa->alive == PARS_DEAD && (part->flag & PART_DIED) == 0) {}
		else if (p % totgr == cur) tot++;
	}
	return tot;
}
/* we allocate path cache memory in chunks instead of a big contiguous
 * chunk, windows' memory allocater fails to find big blocks of memory often */

#define PATH_CACHE_BUF_SIZE 1024

static ParticleCacheKey **psys_alloc_path_cache_buffers(ListBase *bufs, int tot, int steps)
{
	LinkData *buf;
	ParticleCacheKey **cache;
	int i, totkey, totbufkey;

	tot = MAX2(tot, 1);
	totkey = 0;
	cache = MEM_callocN(tot * sizeof(void *), "PathCacheArray");

	while (totkey < tot) {
		totbufkey = MIN2(tot - totkey, PATH_CACHE_BUF_SIZE);
		buf = MEM_callocN(sizeof(LinkData), "PathCacheLinkData");
		buf->data = MEM_callocN(sizeof(ParticleCacheKey) * totbufkey * steps, "ParticleCacheKey");

		for (i = 0; i < totbufkey; i++)
			cache[totkey + i] = ((ParticleCacheKey *)buf->data) + i * steps;

		totkey += totbufkey;
		BLI_addtail(bufs, buf);
	}

	return cache;
}

static void psys_free_path_cache_buffers(ParticleCacheKey **cache, ListBase *bufs)
{
	LinkData *buf;

	if (cache)
		MEM_freeN(cache);

	for (buf = bufs->first; buf; buf = buf->next)
		MEM_freeN(buf->data);
	BLI_freelistN(bufs);
}

/************************************************/
/*			Getting stuff						*/
/************************************************/
/* get object's active particle system safely */
ParticleSystem *psys_get_current(Object *ob)
{
	ParticleSystem *psys;
	if (ob == NULL) return NULL;

	for (psys = ob->particlesystem.first; psys; psys = psys->next) {
		if (psys->flag & PSYS_CURRENT)
			return psys;
	}
	
	return NULL;
}
short psys_get_current_num(Object *ob)
{
	ParticleSystem *psys;
	short i;

	if (ob == NULL) return 0;

	for (psys = ob->particlesystem.first, i = 0; psys; psys = psys->next, i++)
		if (psys->flag & PSYS_CURRENT)
			return i;
	
	return i;
}
void psys_set_current_num(Object *ob, int index)
{
	ParticleSystem *psys;
	short i;

	if (ob == NULL) return;

	for (psys = ob->particlesystem.first, i = 0; psys; psys = psys->next, i++) {
		if (i == index)
			psys->flag |= PSYS_CURRENT;
		else
			psys->flag &= ~PSYS_CURRENT;
	}
}

#if 0 /* UNUSED */
Object *psys_find_object(Scene *scene, ParticleSystem *psys)
{
	Base *base;
	ParticleSystem *tpsys;

	for (base = scene->base.first; base; base = base->next) {
		for (tpsys = base->object->particlesystem.first; psys; psys = psys->next) {
			if (tpsys == psys)
				return base->object;
		}
	}

	return NULL;
}
#endif

struct LatticeDeformData *psys_create_lattice_deform_data(ParticleSimulationData *sim)
{
	struct LatticeDeformData *lattice_deform_data = NULL;

	if (psys_in_edit_mode(sim->scene, sim->psys) == 0) {
		Object *lattice = NULL;
		ModifierData *md = (ModifierData *)psys_get_modifier(sim->ob, sim->psys);

		for (; md; md = md->next) {
			if (md->type == eModifierType_Lattice) {
				LatticeModifierData *lmd = (LatticeModifierData *)md;
				lattice = lmd->object;
				break;
			}
		}
		if (lattice)
			lattice_deform_data = init_latt_deform(lattice, NULL);
	}

	return lattice_deform_data;
}
void psys_disable_all(Object *ob)
{
	ParticleSystem *psys = ob->particlesystem.first;

	for (; psys; psys = psys->next)
		psys->flag |= PSYS_DISABLED;
}
void psys_enable_all(Object *ob)
{
	ParticleSystem *psys = ob->particlesystem.first;

	for (; psys; psys = psys->next)
		psys->flag &= ~PSYS_DISABLED;
}
int psys_in_edit_mode(Scene *scene, ParticleSystem *psys)
{
	return (scene->basact && (scene->basact->object->mode & OB_MODE_PARTICLE_EDIT) && psys == psys_get_current((scene->basact)->object) && (psys->edit || psys->pointcache->edit) && !psys->renderdata);
}
int psys_check_enabled(Object *ob, ParticleSystem *psys)
{
	ParticleSystemModifierData *psmd;

	if (psys->flag & PSYS_DISABLED || psys->flag & PSYS_DELETE || !psys->part)
		return 0;

	psmd = psys_get_modifier(ob, psys);
	if (psys->renderdata || G.is_rendering) {
		if (!(psmd->modifier.mode & eModifierMode_Render))
			return 0;
	}
	else if (!(psmd->modifier.mode & eModifierMode_Realtime))
		return 0;

	return 1;
}

int psys_check_edited(ParticleSystem *psys)
{
	if (psys->part && psys->part->type == PART_HAIR)
		return (psys->flag & PSYS_EDITED || (psys->edit && psys->edit->edited));
	else
		return (psys->pointcache->edit && psys->pointcache->edit->edited);
}

void psys_check_group_weights(ParticleSettings *part)
{
	ParticleDupliWeight *dw, *tdw;
	GroupObject *go;
	int current = 0;

	if (part->ren_as == PART_DRAW_GR && part->dup_group && part->dup_group->gobject.first) {
		/* first remove all weights that don't have an object in the group */
		dw = part->dupliweights.first;
		while (dw) {
			if (!BKE_group_object_exists(part->dup_group, dw->ob)) {
				tdw = dw->next;
				BLI_freelinkN(&part->dupliweights, dw);
				dw = tdw;
			}
			else
				dw = dw->next;
		}

		/* then add objects in the group to new list */
		go = part->dup_group->gobject.first;
		while (go) {
			dw = part->dupliweights.first;
			while (dw && dw->ob != go->ob)
				dw = dw->next;
			
			if (!dw) {
				dw = MEM_callocN(sizeof(ParticleDupliWeight), "ParticleDupliWeight");
				dw->ob = go->ob;
				dw->count = 1;
				BLI_addtail(&part->dupliweights, dw);
			}

			go = go->next;
		}

		dw = part->dupliweights.first;
		for (; dw; dw = dw->next) {
			if (dw->flag & PART_DUPLIW_CURRENT) {
				current = 1;
				break;
			}
		}

		if (!current) {
			dw = part->dupliweights.first;
			if (dw)
				dw->flag |= PART_DUPLIW_CURRENT;
		}
	}
	else {
		BLI_freelistN(&part->dupliweights);
	}
}
int psys_uses_gravity(ParticleSimulationData *sim)
{
	return sim->scene->physics_settings.flag & PHYS_GLOBAL_GRAVITY && sim->psys->part && sim->psys->part->effector_weights->global_gravity != 0.0f;
}
/************************************************/
/*			Freeing stuff						*/
/************************************************/
static void fluid_free_settings(SPHFluidSettings *fluid)
{
	if (fluid)
		MEM_freeN(fluid); 
}

void BKE_particlesettings_free(ParticleSettings *part)
{
	MTex *mtex;
	int a;
	BKE_free_animdata(&part->id);
	free_partdeflect(part->pd);
	free_partdeflect(part->pd2);

	if (part->effector_weights)
		MEM_freeN(part->effector_weights);

	BLI_freelistN(&part->dupliweights);

	boid_free_settings(part->boids);
	fluid_free_settings(part->fluid);

	for (a = 0; a < MAX_MTEX; a++) {
		mtex = part->mtex[a];
		if (mtex && mtex->tex) mtex->tex->id.us--;
		if (mtex) MEM_freeN(mtex);
	}
}

void free_hair(Object *UNUSED(ob), ParticleSystem *psys, int dynamics)
{
	PARTICLE_P;

	LOOP_PARTICLES {
		if (pa->hair)
			MEM_freeN(pa->hair);
		pa->hair = NULL;
		pa->totkey = 0;
	}

	psys->flag &= ~PSYS_HAIR_DONE;

	if (psys->clmd) {
		if (dynamics) {
			BKE_ptcache_free_list(&psys->ptcaches);
			psys->clmd->point_cache = psys->pointcache = NULL;
			BLI_listbase_clear(&psys->clmd->ptcaches);

			modifier_free((ModifierData *)psys->clmd);
			
			psys->clmd = NULL;
			psys->pointcache = BKE_ptcache_add(&psys->ptcaches);
		}
		else {
			cloth_free_modifier(psys->clmd);
		}
	}

	if (psys->hair_in_dm)
		psys->hair_in_dm->release(psys->hair_in_dm);
	psys->hair_in_dm = NULL;

	if (psys->hair_out_dm)
		psys->hair_out_dm->release(psys->hair_out_dm);
	psys->hair_out_dm = NULL;
}
void free_keyed_keys(ParticleSystem *psys)
{
	PARTICLE_P;

	if (psys->part->type == PART_HAIR)
		return;

	if (psys->particles && psys->particles->keys) {
		MEM_freeN(psys->particles->keys);

		LOOP_PARTICLES {
			if (pa->keys) {
				pa->keys = NULL;
				pa->totkey = 0;
			}
		}
	}
}
static void free_child_path_cache(ParticleSystem *psys)
{
	psys_free_path_cache_buffers(psys->childcache, &psys->childcachebufs);
	psys->childcache = NULL;
	psys->totchildcache = 0;
}
void psys_free_path_cache(ParticleSystem *psys, PTCacheEdit *edit)
{
	if (edit) {
		psys_free_path_cache_buffers(edit->pathcache, &edit->pathcachebufs);
		edit->pathcache = NULL;
		edit->totcached = 0;
	}
	if (psys) {
		psys_free_path_cache_buffers(psys->pathcache, &psys->pathcachebufs);
		psys->pathcache = NULL;
		psys->totcached = 0;

		free_child_path_cache(psys);
	}
}
void psys_free_children(ParticleSystem *psys)
{
	if (psys->child) {
		MEM_freeN(psys->child);
		psys->child = NULL;
		psys->totchild = 0;
	}

	free_child_path_cache(psys);
}
void psys_free_particles(ParticleSystem *psys)
{
	PARTICLE_P;

	if (psys->particles) {
		if (psys->part->type == PART_HAIR) {
			LOOP_PARTICLES {
				if (pa->hair)
					MEM_freeN(pa->hair);
			}
		}
		
		if (psys->particles->keys)
			MEM_freeN(psys->particles->keys);
		
		if (psys->particles->boid)
			MEM_freeN(psys->particles->boid);

		MEM_freeN(psys->particles);
		psys->particles = NULL;
		psys->totpart = 0;
	}
}
void psys_free_pdd(ParticleSystem *psys)
{
	if (psys->pdd) {
		if (psys->pdd->cdata)
			MEM_freeN(psys->pdd->cdata);
		psys->pdd->cdata = NULL;

		if (psys->pdd->vdata)
			MEM_freeN(psys->pdd->vdata);
		psys->pdd->vdata = NULL;

		if (psys->pdd->ndata)
			MEM_freeN(psys->pdd->ndata);
		psys->pdd->ndata = NULL;

		if (psys->pdd->vedata)
			MEM_freeN(psys->pdd->vedata);
		psys->pdd->vedata = NULL;

		psys->pdd->totpoint = 0;
		psys->pdd->tot_vec_size = 0;
	}
}
/* free everything */
void psys_free(Object *ob, ParticleSystem *psys)
{	
	if (psys) {
		int nr = 0;
		ParticleSystem *tpsys;
		
		psys_free_path_cache(psys, NULL);

		free_hair(ob, psys, 1);

		psys_free_particles(psys);

		if (psys->edit && psys->free_edit)
			psys->free_edit(psys->edit);

		if (psys->child) {
			MEM_freeN(psys->child);
			psys->child = NULL;
			psys->totchild = 0;
		}
		
		/* check if we are last non-visible particle system */
		for (tpsys = ob->particlesystem.first; tpsys; tpsys = tpsys->next) {
			if (tpsys->part) {
				if (ELEM(tpsys->part->ren_as, PART_DRAW_OB, PART_DRAW_GR)) {
					nr++;
					break;
				}
			}
		}
		/* clear do-not-draw-flag */
		if (!nr)
			ob->transflag &= ~OB_DUPLIPARTS;

		if (psys->part) {
			psys->part->id.us--;
			psys->part = NULL;
		}

		BKE_ptcache_free_list(&psys->ptcaches);
		psys->pointcache = NULL;
		
		BLI_freelistN(&psys->targets);

		BLI_bvhtree_free(psys->bvhtree);
		BLI_kdtree_free(psys->tree);
 
		if (psys->fluid_springs)
			MEM_freeN(psys->fluid_springs);

		pdEndEffectors(&psys->effectors);

		if (psys->pdd) {
			psys_free_pdd(psys);
			MEM_freeN(psys->pdd);
		}

		MEM_freeN(psys);
	}
}

/************************************************/
/*			Rendering							*/
/************************************************/
/* these functions move away particle data and bring it back after
 * rendering, to make different render settings possible without
 * removing the previous data. this should be solved properly once */

typedef struct ParticleRenderElem {
	int curchild, totchild, reduce;
	float lambda, t, scalemin, scalemax;
} ParticleRenderElem;

typedef struct ParticleRenderData {
	ChildParticle *child;
	ParticleCacheKey **pathcache;
	ParticleCacheKey **childcache;
	ListBase pathcachebufs, childcachebufs;
	int totchild, totcached, totchildcache;
	DerivedMesh *dm;
	int totdmvert, totdmedge, totdmface;

	float mat[4][4];
	float viewmat[4][4], winmat[4][4];
	int winx, winy;

	int do_simplify;
	int timeoffset;
	ParticleRenderElem *elems;

	/* ORIGINDEX */
	const int *index_mf_to_mpoly;
	const int *index_mp_to_orig;
} ParticleRenderData;

static float psys_render_viewport_falloff(double rate, float dist, float width)
{
	return pow(rate, dist / width);
}

static float psys_render_projected_area(ParticleSystem *psys, const float center[3], float area, double vprate, float *viewport)
{
	ParticleRenderData *data = psys->renderdata;
	float co[4], view[3], ortho1[3], ortho2[3], w, dx, dy, radius;
	
	/* transform to view space */
	copy_v3_v3(co, center);
	co[3] = 1.0f;
	mul_m4_v4(data->viewmat, co);
	
	/* compute two vectors orthogonal to view vector */
	normalize_v3_v3(view, co);
	ortho_basis_v3v3_v3(ortho1, ortho2, view);

	/* compute on screen minification */
	w = co[2] * data->winmat[2][3] + data->winmat[3][3];
	dx = data->winx * ortho2[0] * data->winmat[0][0];
	dy = data->winy * ortho2[1] * data->winmat[1][1];
	w = sqrtf(dx * dx + dy * dy) / w;

	/* w squared because we are working with area */
	area = area * w * w;

	/* viewport of the screen test */

	/* project point on screen */
	mul_m4_v4(data->winmat, co);
	if (co[3] != 0.0f) {
		co[0] = 0.5f * data->winx * (1.0f + co[0] / co[3]);
		co[1] = 0.5f * data->winy * (1.0f + co[1] / co[3]);
	}

	/* screen space radius */
	radius = sqrtf(area / (float)M_PI);

	/* make smaller using fallof once over screen edge */
	*viewport = 1.0f;

	if (co[0] + radius < 0.0f)
		*viewport *= psys_render_viewport_falloff(vprate, -(co[0] + radius), data->winx);
	else if (co[0] - radius > data->winx)
		*viewport *= psys_render_viewport_falloff(vprate, (co[0] - radius) - data->winx, data->winx);

	if (co[1] + radius < 0.0f)
		*viewport *= psys_render_viewport_falloff(vprate, -(co[1] + radius), data->winy);
	else if (co[1] - radius > data->winy)
		*viewport *= psys_render_viewport_falloff(vprate, (co[1] - radius) - data->winy, data->winy);
	
	return area;
}

void psys_render_set(Object *ob, ParticleSystem *psys, float viewmat[4][4], float winmat[4][4], int winx, int winy, int timeoffset)
{
	ParticleRenderData *data;
	ParticleSystemModifierData *psmd = psys_get_modifier(ob, psys);

	if (psys->renderdata)
		return;

	data = MEM_callocN(sizeof(ParticleRenderData), "ParticleRenderData");

	data->child = psys->child;
	data->totchild = psys->totchild;
	data->pathcache = psys->pathcache;
	data->pathcachebufs.first = psys->pathcachebufs.first;
	data->pathcachebufs.last = psys->pathcachebufs.last;
	data->totcached = psys->totcached;
	data->childcache = psys->childcache;
	data->childcachebufs.first = psys->childcachebufs.first;
	data->childcachebufs.last = psys->childcachebufs.last;
	data->totchildcache = psys->totchildcache;

	if (psmd->dm)
		data->dm = CDDM_copy(psmd->dm);
	data->totdmvert = psmd->totdmvert;
	data->totdmedge = psmd->totdmedge;
	data->totdmface = psmd->totdmface;

	psys->child = NULL;
	psys->pathcache = NULL;
	psys->childcache = NULL;
	psys->totchild = psys->totcached = psys->totchildcache = 0;
	BLI_listbase_clear(&psys->pathcachebufs);
	BLI_listbase_clear(&psys->childcachebufs);

	copy_m4_m4(data->winmat, winmat);
	mul_m4_m4m4(data->viewmat, viewmat, ob->obmat);
	mul_m4_m4m4(data->mat, winmat, data->viewmat);
	data->winx = winx;
	data->winy = winy;

	data->timeoffset = timeoffset;

	psys->renderdata = data;

	/* Hair can and has to be recalculated if everything isn't displayed. */
	if (psys->part->disp != 100 && psys->part->type == PART_HAIR)
		psys->recalc |= PSYS_RECALC_RESET;
}

void psys_render_restore(Object *ob, ParticleSystem *psys)
{
	ParticleRenderData *data;
	ParticleSystemModifierData *psmd = psys_get_modifier(ob, psys);
	float render_disp = psys_get_current_display_percentage(psys);
	float disp;

	data = psys->renderdata;
	if (!data)
		return;
	
	if (data->elems)
		MEM_freeN(data->elems);

	if (psmd->dm) {
		psmd->dm->needsFree = 1;
		psmd->dm->release(psmd->dm);
	}

	psys_free_path_cache(psys, NULL);

	if (psys->child) {
		MEM_freeN(psys->child);
		psys->child = 0;
		psys->totchild = 0;
	}

	psys->child = data->child;
	psys->totchild = data->totchild;
	psys->pathcache = data->pathcache;
	psys->pathcachebufs.first = data->pathcachebufs.first;
	psys->pathcachebufs.last = data->pathcachebufs.last;
	psys->totcached = data->totcached;
	psys->childcache = data->childcache;
	psys->childcachebufs.first = data->childcachebufs.first;
	psys->childcachebufs.last = data->childcachebufs.last;
	psys->totchildcache = data->totchildcache;

	psmd->dm = data->dm;
	psmd->totdmvert = data->totdmvert;
	psmd->totdmedge = data->totdmedge;
	psmd->totdmface = data->totdmface;
	psmd->flag &= ~eParticleSystemFlag_psys_updated;

	if (psmd->dm)
		psys_calc_dmcache(ob, psmd->dm, psys);

	MEM_freeN(data);
	psys->renderdata = NULL;

	/* restore particle display percentage */
	disp = psys_get_current_display_percentage(psys);

	if (disp != render_disp) {
		PARTICLE_P;

		LOOP_PARTICLES {
			if (psys_frand(psys, p) > disp)
				pa->flag |= PARS_NO_DISP;
			else
				pa->flag &= ~PARS_NO_DISP;
		}
	}
}

/* BMESH_TODO, for orig face data, we need to use MPoly */

int psys_render_simplify_distribution(ParticleThreadContext *ctx, int tot)
{
	DerivedMesh *dm = ctx->dm;
	Mesh *me = (Mesh *)(ctx->sim.ob->data);
	MFace *mf, *mface;
	MVert *mvert;
	ParticleRenderData *data;
	ParticleRenderElem *elems, *elem;
	ParticleSettings *part = ctx->sim.psys->part;
	float *facearea, (*facecenter)[3], size[3], fac, powrate, scaleclamp;
	float co1[3], co2[3], co3[3], co4[3], lambda, arearatio, t, area, viewport;
	double vprate;
	int *facetotvert;
	int a, b, totorigface, totface, newtot, skipped;

	/* double lookup */
	const int *index_mf_to_mpoly;
	const int *index_mp_to_orig;

	if (part->ren_as != PART_DRAW_PATH || !(part->draw & PART_DRAW_REN_STRAND))
		return tot;
	if (!ctx->sim.psys->renderdata)
		return tot;

	data = ctx->sim.psys->renderdata;
	if (data->timeoffset)
		return 0;
	if (!(part->simplify_flag & PART_SIMPLIFY_ENABLE))
		return tot;

	mvert = dm->getVertArray(dm);
	mface = dm->getTessFaceArray(dm);
	totface = dm->getNumTessFaces(dm);
	totorigface = me->totpoly;

	if (totface == 0 || totorigface == 0)
		return tot;

	index_mf_to_mpoly = dm->getTessFaceDataArray(dm, CD_ORIGINDEX);
	index_mp_to_orig  = dm->getPolyDataArray(dm, CD_ORIGINDEX);
	if (index_mf_to_mpoly == NULL) {
		index_mp_to_orig = NULL;
	}

	facearea = MEM_callocN(sizeof(float) * totorigface, "SimplifyFaceArea");
	facecenter = MEM_callocN(sizeof(float[3]) * totorigface, "SimplifyFaceCenter");
	facetotvert = MEM_callocN(sizeof(int) * totorigface, "SimplifyFaceArea");
	elems = MEM_callocN(sizeof(ParticleRenderElem) * totorigface, "SimplifyFaceElem");

	if (data->elems)
		MEM_freeN(data->elems);

	data->do_simplify = true;
	data->elems = elems;
	data->index_mf_to_mpoly = index_mf_to_mpoly;
	data->index_mp_to_orig  = index_mp_to_orig;

	/* compute number of children per original face */
	for (a = 0; a < tot; a++) {
		b = (index_mf_to_mpoly) ? DM_origindex_mface_mpoly(index_mf_to_mpoly, index_mp_to_orig, ctx->index[a]) : ctx->index[a];
		if (b != ORIGINDEX_NONE) {
			elems[b].totchild++;
		}
	}

	/* compute areas and centers of original faces */
	for (mf = mface, a = 0; a < totface; a++, mf++) {
		b = (index_mf_to_mpoly) ? DM_origindex_mface_mpoly(index_mf_to_mpoly, index_mp_to_orig, a) : a;

		if (b != ORIGINDEX_NONE) {
			copy_v3_v3(co1, mvert[mf->v1].co);
			copy_v3_v3(co2, mvert[mf->v2].co);
			copy_v3_v3(co3, mvert[mf->v3].co);

			add_v3_v3(facecenter[b], co1);
			add_v3_v3(facecenter[b], co2);
			add_v3_v3(facecenter[b], co3);

			if (mf->v4) {
				copy_v3_v3(co4, mvert[mf->v4].co);
				add_v3_v3(facecenter[b], co4);
				facearea[b] += area_quad_v3(co1, co2, co3, co4);
				facetotvert[b] += 4;
			}
			else {
				facearea[b] += area_tri_v3(co1, co2, co3);
				facetotvert[b] += 3;
			}
		}
	}

	for (a = 0; a < totorigface; a++)
		if (facetotvert[a] > 0)
			mul_v3_fl(facecenter[a], 1.0f / facetotvert[a]);

	/* for conversion from BU area / pixel area to reference screen size */
	BKE_mesh_texspace_get(me, 0, 0, size);
	fac = ((size[0] + size[1] + size[2]) / 3.0f) / part->simplify_refsize;
	fac = fac * fac;

	powrate = log(0.5f) / log(part->simplify_rate * 0.5f);
	if (part->simplify_flag & PART_SIMPLIFY_VIEWPORT)
		vprate = pow(1.0f - part->simplify_viewport, 5.0);
	else
		vprate = 1.0;

	/* set simplification parameters per original face */
	for (a = 0, elem = elems; a < totorigface; a++, elem++) {
		area = psys_render_projected_area(ctx->sim.psys, facecenter[a], facearea[a], vprate, &viewport);
		arearatio = fac * area / facearea[a];

		if ((arearatio < 1.0f || viewport < 1.0f) && elem->totchild) {
			/* lambda is percentage of elements to keep */
			lambda = (arearatio < 1.0f) ? powf(arearatio, powrate) : 1.0f;
			lambda *= viewport;

			lambda = MAX2(lambda, 1.0f / elem->totchild);

			/* compute transition region */
			t = part->simplify_transition;
			elem->t = (lambda - t < 0.0f) ? lambda : (lambda + t > 1.0f) ? 1.0f - lambda : t;
			elem->reduce = 1;

			/* scale at end and beginning of the transition region */
			elem->scalemax = (lambda + t < 1.0f) ? 1.0f / lambda : 1.0f / (1.0f - elem->t * elem->t / t);
			elem->scalemin = (lambda + t < 1.0f) ? 0.0f : elem->scalemax * (1.0f - elem->t / t);

			elem->scalemin = sqrtf(elem->scalemin);
			elem->scalemax = sqrtf(elem->scalemax);

			/* clamp scaling */
			scaleclamp = (float)min_ii(elem->totchild, 10);
			elem->scalemin = MIN2(scaleclamp, elem->scalemin);
			elem->scalemax = MIN2(scaleclamp, elem->scalemax);

			/* extend lambda to include transition */
			lambda = lambda + elem->t;
			if (lambda > 1.0f)
				lambda = 1.0f;
		}
		else {
			lambda = arearatio;

			elem->scalemax = 1.0f; //sqrt(lambda);
			elem->scalemin = 1.0f; //sqrt(lambda);
			elem->reduce = 0;
		}

		elem->lambda = lambda;
		elem->scalemin = sqrtf(elem->scalemin);
		elem->scalemax = sqrtf(elem->scalemax);
		elem->curchild = 0;
	}

	MEM_freeN(facearea);
	MEM_freeN(facecenter);
	MEM_freeN(facetotvert);

	/* move indices and set random number skipping */
	ctx->skip = MEM_callocN(sizeof(int) * tot, "SimplificationSkip");

	skipped = 0;
	for (a = 0, newtot = 0; a < tot; a++) {
		b = (index_mf_to_mpoly) ? DM_origindex_mface_mpoly(index_mf_to_mpoly, index_mp_to_orig, ctx->index[a]) : ctx->index[a];

		if (b != ORIGINDEX_NONE) {
			if (elems[b].curchild++ < ceil(elems[b].lambda * elems[b].totchild)) {
				ctx->index[newtot] = ctx->index[a];
				ctx->skip[newtot] = skipped;
				skipped = 0;
				newtot++;
			}
			else skipped++;
		}
		else skipped++;
	}

	for (a = 0, elem = elems; a < totorigface; a++, elem++)
		elem->curchild = 0;

	return newtot;
}

bool psys_render_simplify_params(ParticleSystem *psys, ChildParticle *cpa, float *params)
{
	ParticleRenderData *data;
	ParticleRenderElem *elem;
	float x, w, scale, alpha, lambda, t, scalemin, scalemax;
	int b;

	if (!(psys->renderdata && (psys->part->simplify_flag & PART_SIMPLIFY_ENABLE)))
		return 0;
	
	data = psys->renderdata;
	if (!data->do_simplify)
		return 0;
	b = (data->index_mf_to_mpoly) ? DM_origindex_mface_mpoly(data->index_mf_to_mpoly, data->index_mp_to_orig, cpa->num) : cpa->num;
	if (b == ORIGINDEX_NONE) {
		return 0;
	}

	elem = &data->elems[b];

	lambda = elem->lambda;
	t = elem->t;
	scalemin = elem->scalemin;
	scalemax = elem->scalemax;

	if (!elem->reduce) {
		scale = scalemin;
		alpha = 1.0f;
	}
	else {
		x = (elem->curchild + 0.5f) / elem->totchild;
		if (x < lambda - t) {
			scale = scalemax;
			alpha = 1.0f;
		}
		else if (x >= lambda + t) {
			scale = scalemin;
			alpha = 0.0f;
		}
		else {
			w = (lambda + t - x) / (2.0f * t);
			scale = scalemin + (scalemax - scalemin) * w;
			alpha = w;
		}
	}

	params[0] = scale;
	params[1] = alpha;

	elem->curchild++;

	return 1;
}

/************************************************/
/*			Interpolation						*/
/************************************************/
static float interpolate_particle_value(float v1, float v2, float v3, float v4, const float w[4], int four)
{
	float value;

	value = w[0] * v1 + w[1] * v2 + w[2] * v3;
	if (four)
		value += w[3] * v4;

	CLAMP(value, 0.f, 1.f);
	
	return value;
}

void psys_interpolate_particle(short type, ParticleKey keys[4], float dt, ParticleKey *result, bool velocity)
{
	float t[4];

	if (type < 0) {
		interp_cubic_v3(result->co, result->vel, keys[1].co, keys[1].vel, keys[2].co, keys[2].vel, dt);
	}
	else {
		key_curve_position_weights(dt, t, type);

		interp_v3_v3v3v3v3(result->co, keys[0].co, keys[1].co, keys[2].co, keys[3].co, t);

		if (velocity) {
			float temp[3];

			if (dt > 0.999f) {
				key_curve_position_weights(dt - 0.001f, t, type);
				interp_v3_v3v3v3v3(temp, keys[0].co, keys[1].co, keys[2].co, keys[3].co, t);
				sub_v3_v3v3(result->vel, result->co, temp);
			}
			else {
				key_curve_position_weights(dt + 0.001f, t, type);
				interp_v3_v3v3v3v3(temp, keys[0].co, keys[1].co, keys[2].co, keys[3].co, t);
				sub_v3_v3v3(result->vel, temp, result->co);
			}
		}
	}
}


typedef struct ParticleInterpolationData {
	HairKey *hkey[2];

	DerivedMesh *dm;
	MVert *mvert[2];

	int keyed;
	ParticleKey *kkey[2];

	PointCache *cache;
	PTCacheMem *pm;

	PTCacheEditPoint *epoint;
	PTCacheEditKey *ekey[2];

	float birthtime, dietime;
	int bspline;
} ParticleInterpolationData;
/* Assumes pointcache->mem_cache exists, so for disk cached particles call psys_make_temp_pointcache() before use */
/* It uses ParticleInterpolationData->pm to store the current memory cache frame so it's thread safe. */
static void get_pointcache_keys_for_time(Object *UNUSED(ob), PointCache *cache, PTCacheMem **cur, int index, float t, ParticleKey *key1, ParticleKey *key2)
{
	static PTCacheMem *pm = NULL;
	int index1, index2;

	if (index < 0) { /* initialize */
		*cur = cache->mem_cache.first;

		if (*cur)
			*cur = (*cur)->next;
	}
	else {
		if (*cur) {
			while (*cur && (*cur)->next && (float)(*cur)->frame < t)
				*cur = (*cur)->next;

			pm = *cur;

			index2 = BKE_ptcache_mem_index_find(pm, index);
			index1 = BKE_ptcache_mem_index_find(pm->prev, index);

			BKE_ptcache_make_particle_key(key2, index2, pm->data, (float)pm->frame);
			if (index1 < 0)
				copy_particle_key(key1, key2, 1);
			else
				BKE_ptcache_make_particle_key(key1, index1, pm->prev->data, (float)pm->prev->frame);
		}
		else if (cache->mem_cache.first) {
			pm = cache->mem_cache.first;
			index2 = BKE_ptcache_mem_index_find(pm, index);
			BKE_ptcache_make_particle_key(key2, index2, pm->data, (float)pm->frame);
			copy_particle_key(key1, key2, 1);
		}
	}
}
static int get_pointcache_times_for_particle(PointCache *cache, int index, float *start, float *end)
{
	PTCacheMem *pm;
	int ret = 0;

	for (pm = cache->mem_cache.first; pm; pm = pm->next) {
		if (BKE_ptcache_mem_index_find(pm, index) >= 0) {
			*start = pm->frame;
			ret++;
			break;
		}
	}

	for (pm = cache->mem_cache.last; pm; pm = pm->prev) {
		if (BKE_ptcache_mem_index_find(pm, index) >= 0) {
			*end = pm->frame;
			ret++;
			break;
		}
	}

	return ret == 2;
}

float psys_get_dietime_from_cache(PointCache *cache, int index)
{
	PTCacheMem *pm;
	int dietime = 10000000; /* some max value so that we can default to pa->time+lifetime */

	for (pm = cache->mem_cache.last; pm; pm = pm->prev) {
		if (BKE_ptcache_mem_index_find(pm, index) >= 0)
			return (float)pm->frame;
	}

	return (float)dietime;
}

static void init_particle_interpolation(Object *ob, ParticleSystem *psys, ParticleData *pa, ParticleInterpolationData *pind)
{

	if (pind->epoint) {
		PTCacheEditPoint *point = pind->epoint;

		pind->ekey[0] = point->keys;
		pind->ekey[1] = point->totkey > 1 ? point->keys + 1 : NULL;

		pind->birthtime = *(point->keys->time);
		pind->dietime = *((point->keys + point->totkey - 1)->time);
	}
	else if (pind->keyed) {
		ParticleKey *key = pa->keys;
		pind->kkey[0] = key;
		pind->kkey[1] = pa->totkey > 1 ? key + 1 : NULL;

		pind->birthtime = key->time;
		pind->dietime = (key + pa->totkey - 1)->time;
	}
	else if (pind->cache) {
		float start = 0.0f, end = 0.0f;
		get_pointcache_keys_for_time(ob, pind->cache, &pind->pm, -1, 0.0f, NULL, NULL);
		pind->birthtime = pa ? pa->time : pind->cache->startframe;
		pind->dietime = pa ? pa->dietime : pind->cache->endframe;

		if (get_pointcache_times_for_particle(pind->cache, pa - psys->particles, &start, &end)) {
			pind->birthtime = MAX2(pind->birthtime, start);
			pind->dietime = MIN2(pind->dietime, end);
		}
	}
	else {
		HairKey *key = pa->hair;
		pind->hkey[0] = key;
		pind->hkey[1] = key + 1;

		pind->birthtime = key->time;
		pind->dietime = (key + pa->totkey - 1)->time;

		if (pind->dm) {
			pind->mvert[0] = CDDM_get_vert(pind->dm, pa->hair_index);
			pind->mvert[1] = pind->mvert[0] + 1;
		}
	}
}
static void edit_to_particle(ParticleKey *key, PTCacheEditKey *ekey)
{
	copy_v3_v3(key->co, ekey->co);
	if (ekey->vel) {
		copy_v3_v3(key->vel, ekey->vel);
	}
	key->time = *(ekey->time);
}
static void hair_to_particle(ParticleKey *key, HairKey *hkey)
{
	copy_v3_v3(key->co, hkey->co);
	key->time = hkey->time;
}

static void mvert_to_particle(ParticleKey *key, MVert *mvert, HairKey *hkey)
{
	copy_v3_v3(key->co, mvert->co);
	key->time = hkey->time;
}

static void do_particle_interpolation(ParticleSystem *psys, int p, ParticleData *pa, float t, ParticleInterpolationData *pind, ParticleKey *result)
{
	PTCacheEditPoint *point = pind->epoint;
	ParticleKey keys[4];
	int point_vel = (point && point->keys->vel);
	float real_t, dfra, keytime, invdt = 1.f;

	/* billboards wont fill in all of these, so start cleared */
	memset(keys, 0, sizeof(keys));

	/* interpret timing and find keys */
	if (point) {
		if (result->time < 0.0f)
			real_t = -result->time;
		else
			real_t = *(pind->ekey[0]->time) + t * (*(pind->ekey[0][point->totkey - 1].time) - *(pind->ekey[0]->time));

		while (*(pind->ekey[1]->time) < real_t)
			pind->ekey[1]++;

		pind->ekey[0] = pind->ekey[1] - 1;
	}
	else if (pind->keyed) {
		/* we have only one key, so let's use that */
		if (pind->kkey[1] == NULL) {
			copy_particle_key(result, pind->kkey[0], 1);
			return;
		}

		if (result->time < 0.0f)
			real_t = -result->time;
		else
			real_t = pind->kkey[0]->time + t * (pind->kkey[0][pa->totkey - 1].time - pind->kkey[0]->time);

		if (psys->part->phystype == PART_PHYS_KEYED && psys->flag & PSYS_KEYED_TIMING) {
			ParticleTarget *pt = psys->targets.first;

			pt = pt->next;

			while (pt && pa->time + pt->time < real_t)
				pt = pt->next;

			if (pt) {
				pt = pt->prev;

				if (pa->time + pt->time + pt->duration > real_t)
					real_t = pa->time + pt->time;
			}
			else
				real_t = pa->time + ((ParticleTarget *)psys->targets.last)->time;
		}

		CLAMP(real_t, pa->time, pa->dietime);

		while (pind->kkey[1]->time < real_t)
			pind->kkey[1]++;
		
		pind->kkey[0] = pind->kkey[1] - 1;
	}
	else if (pind->cache) {
		if (result->time < 0.0f) /* flag for time in frames */
			real_t = -result->time;
		else
			real_t = pa->time + t * (pa->dietime - pa->time);
	}
	else {
		if (result->time < 0.0f)
			real_t = -result->time;
		else
			real_t = pind->hkey[0]->time + t * (pind->hkey[0][pa->totkey - 1].time - pind->hkey[0]->time);

		while (pind->hkey[1]->time < real_t) {
			pind->hkey[1]++;
			pind->mvert[1]++;
		}

		pind->hkey[0] = pind->hkey[1] - 1;
	}

	/* set actual interpolation keys */
	if (point) {
		edit_to_particle(keys + 1, pind->ekey[0]);
		edit_to_particle(keys + 2, pind->ekey[1]);
	}
	else if (pind->dm) {
		pind->mvert[0] = pind->mvert[1] - 1;
		mvert_to_particle(keys + 1, pind->mvert[0], pind->hkey[0]);
		mvert_to_particle(keys + 2, pind->mvert[1], pind->hkey[1]);
	}
	else if (pind->keyed) {
		memcpy(keys + 1, pind->kkey[0], sizeof(ParticleKey));
		memcpy(keys + 2, pind->kkey[1], sizeof(ParticleKey));
	}
	else if (pind->cache) {
		get_pointcache_keys_for_time(NULL, pind->cache, &pind->pm, p, real_t, keys + 1, keys + 2);
	}
	else {
		hair_to_particle(keys + 1, pind->hkey[0]);
		hair_to_particle(keys + 2, pind->hkey[1]);
	}

	/* set secondary interpolation keys for hair */
	if (!pind->keyed && !pind->cache && !point_vel) {
		if (point) {
			if (pind->ekey[0] != point->keys)
				edit_to_particle(keys, pind->ekey[0] - 1);
			else
				edit_to_particle(keys, pind->ekey[0]);
		}
		else if (pind->dm) {
			if (pind->hkey[0] != pa->hair)
				mvert_to_particle(keys, pind->mvert[0] - 1, pind->hkey[0] - 1);
			else
				mvert_to_particle(keys, pind->mvert[0], pind->hkey[0]);
		}
		else {
			if (pind->hkey[0] != pa->hair)
				hair_to_particle(keys, pind->hkey[0] - 1);
			else
				hair_to_particle(keys, pind->hkey[0]);
		}

		if (point) {
			if (pind->ekey[1] != point->keys + point->totkey - 1)
				edit_to_particle(keys + 3, pind->ekey[1] + 1);
			else
				edit_to_particle(keys + 3, pind->ekey[1]);
		}
		else if (pind->dm) {
			if (pind->hkey[1] != pa->hair + pa->totkey - 1)
				mvert_to_particle(keys + 3, pind->mvert[1] + 1, pind->hkey[1] + 1);
			else
				mvert_to_particle(keys + 3, pind->mvert[1], pind->hkey[1]);
		}
		else {
			if (pind->hkey[1] != pa->hair + pa->totkey - 1)
				hair_to_particle(keys + 3, pind->hkey[1] + 1);
			else
				hair_to_particle(keys + 3, pind->hkey[1]);
		}
	}

	dfra = keys[2].time - keys[1].time;
	keytime = (real_t - keys[1].time) / dfra;

	/* convert velocity to timestep size */
	if (pind->keyed || pind->cache || point_vel) {
		invdt = dfra * 0.04f * (psys ? psys->part->timetweak : 1.f);
		mul_v3_fl(keys[1].vel, invdt);
		mul_v3_fl(keys[2].vel, invdt);
		interp_qt_qtqt(result->rot, keys[1].rot, keys[2].rot, keytime);
	}

	/* now we should have in chronologiacl order k1<=k2<=t<=k3<=k4 with keytime between [0, 1]->[k2, k3] (k1 & k4 used for cardinal & bspline interpolation)*/
	psys_interpolate_particle((pind->keyed || pind->cache || point_vel) ? -1 /* signal for cubic interpolation */
	                          : (pind->bspline ? KEY_BSPLINE : KEY_CARDINAL),
	                          keys, keytime, result, 1);

	/* the velocity needs to be converted back from cubic interpolation */
	if (pind->keyed || pind->cache || point_vel)
		mul_v3_fl(result->vel, 1.f / invdt);
}

static void interpolate_pathcache(ParticleCacheKey *first, float t, ParticleCacheKey *result)
{
	int i = 0;
	ParticleCacheKey *cur = first;

	/* scale the requested time to fit the entire path even if the path is cut early */
	t *= (first + first->steps)->time;

	while (i < first->steps && cur->time < t)
		cur++;

	if (cur->time == t)
		*result = *cur;
	else {
		float dt = (t - (cur - 1)->time) / (cur->time - (cur - 1)->time);
		interp_v3_v3v3(result->co, (cur - 1)->co, cur->co, dt);
		interp_v3_v3v3(result->vel, (cur - 1)->vel, cur->vel, dt);
		interp_qt_qtqt(result->rot, (cur - 1)->rot, cur->rot, dt);
		result->time = t;
	}

	/* first is actual base rotation, others are incremental from first */
	if (cur == first || cur - 1 == first)
		copy_qt_qt(result->rot, first->rot);
	else
		mul_qt_qtqt(result->rot, first->rot, result->rot);
}

/************************************************/
/*			Particles on a dm					*/
/************************************************/
/* interpolate a location on a face based on face coordinates */
void psys_interpolate_face(MVert *mvert, MFace *mface, MTFace *tface, float (*orcodata)[3],
                           float w[4], float vec[3], float nor[3], float utan[3], float vtan[3],
                           float orco[3], float ornor[3])
{
	float *v1 = 0, *v2 = 0, *v3 = 0, *v4 = 0;
	float e1[3], e2[3], s1, s2, t1, t2;
	float *uv1, *uv2, *uv3, *uv4;
	float n1[3], n2[3], n3[3], n4[3];
	float tuv[4][2];
	float *o1, *o2, *o3, *o4;

	v1 = mvert[mface->v1].co;
	v2 = mvert[mface->v2].co;
	v3 = mvert[mface->v3].co;

	normal_short_to_float_v3(n1, mvert[mface->v1].no);
	normal_short_to_float_v3(n2, mvert[mface->v2].no);
	normal_short_to_float_v3(n3, mvert[mface->v3].no);

	if (mface->v4) {
		v4 = mvert[mface->v4].co;
		normal_short_to_float_v3(n4, mvert[mface->v4].no);
		
		interp_v3_v3v3v3v3(vec, v1, v2, v3, v4, w);

		if (nor) {
			if (mface->flag & ME_SMOOTH)
				interp_v3_v3v3v3v3(nor, n1, n2, n3, n4, w);
			else
				normal_quad_v3(nor, v1, v2, v3, v4);
		}
	}
	else {
		interp_v3_v3v3v3(vec, v1, v2, v3, w);

		if (nor) {
			if (mface->flag & ME_SMOOTH)
				interp_v3_v3v3v3(nor, n1, n2, n3, w);
			else
				normal_tri_v3(nor, v1, v2, v3);
		}
	}
	
	/* calculate tangent vectors */
	if (utan && vtan) {
		if (tface) {
			uv1 = tface->uv[0];
			uv2 = tface->uv[1];
			uv3 = tface->uv[2];
			uv4 = tface->uv[3];
		}
		else {
			uv1 = tuv[0]; uv2 = tuv[1]; uv3 = tuv[2]; uv4 = tuv[3];
			map_to_sphere(uv1, uv1 + 1, v1[0], v1[1], v1[2]);
			map_to_sphere(uv2, uv2 + 1, v2[0], v2[1], v2[2]);
			map_to_sphere(uv3, uv3 + 1, v3[0], v3[1], v3[2]);
			if (v4)
				map_to_sphere(uv4, uv4 + 1, v4[0], v4[1], v4[2]);
		}

		if (v4) {
			s1 = uv3[0] - uv1[0];
			s2 = uv4[0] - uv1[0];

			t1 = uv3[1] - uv1[1];
			t2 = uv4[1] - uv1[1];

			sub_v3_v3v3(e1, v3, v1);
			sub_v3_v3v3(e2, v4, v1);
		}
		else {
			s1 = uv2[0] - uv1[0];
			s2 = uv3[0] - uv1[0];

			t1 = uv2[1] - uv1[1];
			t2 = uv3[1] - uv1[1];

			sub_v3_v3v3(e1, v2, v1);
			sub_v3_v3v3(e2, v3, v1);
		}

		vtan[0] = (s1 * e2[0] - s2 * e1[0]);
		vtan[1] = (s1 * e2[1] - s2 * e1[1]);
		vtan[2] = (s1 * e2[2] - s2 * e1[2]);

		utan[0] = (t1 * e2[0] - t2 * e1[0]);
		utan[1] = (t1 * e2[1] - t2 * e1[1]);
		utan[2] = (t1 * e2[2] - t2 * e1[2]);
	}

	if (orco) {
		if (orcodata) {
			o1 = orcodata[mface->v1];
			o2 = orcodata[mface->v2];
			o3 = orcodata[mface->v3];

			if (mface->v4) {
				o4 = orcodata[mface->v4];

				interp_v3_v3v3v3v3(orco, o1, o2, o3, o4, w);

				if (ornor)
					normal_quad_v3(ornor, o1, o2, o3, o4);
			}
			else {
				interp_v3_v3v3v3(orco, o1, o2, o3, w);

				if (ornor)
					normal_tri_v3(ornor, o1, o2, o3);
			}
		}
		else {
			copy_v3_v3(orco, vec);
			if (ornor && nor)
				copy_v3_v3(ornor, nor);
		}
	}
}
void psys_interpolate_uvs(const MTFace *tface, int quad, const float w[4], float uvco[2])
{
	float v10 = tface->uv[0][0];
	float v11 = tface->uv[0][1];
	float v20 = tface->uv[1][0];
	float v21 = tface->uv[1][1];
	float v30 = tface->uv[2][0];
	float v31 = tface->uv[2][1];
	float v40, v41;

	if (quad) {
		v40 = tface->uv[3][0];
		v41 = tface->uv[3][1];

		uvco[0] = w[0] * v10 + w[1] * v20 + w[2] * v30 + w[3] * v40;
		uvco[1] = w[0] * v11 + w[1] * v21 + w[2] * v31 + w[3] * v41;
	}
	else {
		uvco[0] = w[0] * v10 + w[1] * v20 + w[2] * v30;
		uvco[1] = w[0] * v11 + w[1] * v21 + w[2] * v31;
	}
}

void psys_interpolate_mcol(const MCol *mcol, int quad, const float w[4], MCol *mc)
{
	char *cp, *cp1, *cp2, *cp3, *cp4;

	cp = (char *)mc;
	cp1 = (char *)&mcol[0];
	cp2 = (char *)&mcol[1];
	cp3 = (char *)&mcol[2];
	
	if (quad) {
		cp4 = (char *)&mcol[3];

		cp[0] = (int)(w[0] * cp1[0] + w[1] * cp2[0] + w[2] * cp3[0] + w[3] * cp4[0]);
		cp[1] = (int)(w[0] * cp1[1] + w[1] * cp2[1] + w[2] * cp3[1] + w[3] * cp4[1]);
		cp[2] = (int)(w[0] * cp1[2] + w[1] * cp2[2] + w[2] * cp3[2] + w[3] * cp4[2]);
		cp[3] = (int)(w[0] * cp1[3] + w[1] * cp2[3] + w[2] * cp3[3] + w[3] * cp4[3]);
	}
	else {
		cp[0] = (int)(w[0] * cp1[0] + w[1] * cp2[0] + w[2] * cp3[0]);
		cp[1] = (int)(w[0] * cp1[1] + w[1] * cp2[1] + w[2] * cp3[1]);
		cp[2] = (int)(w[0] * cp1[2] + w[1] * cp2[2] + w[2] * cp3[2]);
		cp[3] = (int)(w[0] * cp1[3] + w[1] * cp2[3] + w[2] * cp3[3]);
	}
}

static float psys_interpolate_value_from_verts(DerivedMesh *dm, short from, int index, const float fw[4], const float *values)
{
	if (values == 0 || index == -1)
		return 0.0;

	switch (from) {
		case PART_FROM_VERT:
			return values[index];
		case PART_FROM_FACE:
		case PART_FROM_VOLUME:
		{
			MFace *mf = dm->getTessFaceData(dm, index, CD_MFACE);
			return interpolate_particle_value(values[mf->v1], values[mf->v2], values[mf->v3], values[mf->v4], fw, mf->v4);
		}
			
	}
	return 0.0f;
}

/* conversion of pa->fw to origspace layer coordinates */
static void psys_w_to_origspace(const float w[4], float uv[2])
{
	uv[0] = w[1] + w[2];
	uv[1] = w[2] + w[3];
}

/* conversion of pa->fw to weights in face from origspace */
static void psys_origspace_to_w(OrigSpaceFace *osface, int quad, const float w[4], float neww[4])
{
	float v[4][3], co[3];

	v[0][0] = osface->uv[0][0]; v[0][1] = osface->uv[0][1]; v[0][2] = 0.0f;
	v[1][0] = osface->uv[1][0]; v[1][1] = osface->uv[1][1]; v[1][2] = 0.0f;
	v[2][0] = osface->uv[2][0]; v[2][1] = osface->uv[2][1]; v[2][2] = 0.0f;

	psys_w_to_origspace(w, co);
	co[2] = 0.0f;
	
	if (quad) {
		v[3][0] = osface->uv[3][0]; v[3][1] = osface->uv[3][1]; v[3][2] = 0.0f;
		interp_weights_poly_v3(neww, v, 4, co);
	}
	else {
		interp_weights_poly_v3(neww, v, 3, co);
		neww[3] = 0.0f;
	}
}

/* find the derived mesh face for a particle, set the mf passed. this is slow
 * and can be optimized but only for many lookups. returns the face index. */
int psys_particle_dm_face_lookup(Object *ob, DerivedMesh *dm, int index, const float fw[4], struct LinkNode *node)
{
	Mesh *me = (Mesh *)ob->data;
	MPoly *mpoly;
	OrigSpaceFace *osface;
	int quad, findex, totface;
	float uv[2], (*faceuv)[2];

	/* double lookup */
	const int *index_mf_to_mpoly = dm->getTessFaceDataArray(dm, CD_ORIGINDEX);
	const int *index_mp_to_orig  = dm->getPolyDataArray(dm, CD_ORIGINDEX);
	if (index_mf_to_mpoly == NULL) {
		index_mp_to_orig = NULL;
	}

	totface = dm->getNumTessFaces(dm);
	if (!totface) {
		return DMCACHE_NOTFOUND;
	}

	mpoly = dm->getPolyArray(dm);
	osface = dm->getTessFaceDataArray(dm, CD_ORIGSPACE);

	if (osface == NULL || index_mf_to_mpoly == NULL) {
		/* Assume we don't need osface data */
		if (index < totface) {
			//printf("\tNO CD_ORIGSPACE, assuming not needed\n");
			return index;
		}
		else {
			printf("\tNO CD_ORIGSPACE, error out of range\n");
			return DMCACHE_NOTFOUND;
		}
	}
	else if (index >= me->totpoly)
		return DMCACHE_NOTFOUND;  /* index not in the original mesh */

	psys_w_to_origspace(fw, uv);
	
	if (node) { /* we have a linked list of faces that we use, faster! */
		for (; node; node = node->next) {
			findex = GET_INT_FROM_POINTER(node->link);
			faceuv = osface[findex].uv;
			quad = (mpoly[findex].totloop == 4);

			/* check that this intersects - Its possible this misses :/ -
			 * could also check its not between */
			if (quad) {
				if (isect_point_quad_v2(uv, faceuv[0], faceuv[1], faceuv[2], faceuv[3]))
					return findex;
			}
			else if (isect_point_tri_v2(uv, faceuv[0], faceuv[1], faceuv[2]))
				return findex;
		}
	}
	else { /* if we have no node, try every face */
		for (findex = 0; findex < totface; findex++) {
			const int findex_orig = DM_origindex_mface_mpoly(index_mf_to_mpoly, index_mp_to_orig, findex);
			if (findex_orig == index) {
				faceuv = osface[findex].uv;
				quad = (mpoly[findex].totloop == 4);

				/* check that this intersects - Its possible this misses :/ -
				 * could also check its not between */
				if (quad) {
					if (isect_point_quad_v2(uv, faceuv[0], faceuv[1], faceuv[2], faceuv[3]))
						return findex;
				}
				else if (isect_point_tri_v2(uv, faceuv[0], faceuv[1], faceuv[2]))
					return findex;
			}
		}
	}

	return DMCACHE_NOTFOUND;
}

static int psys_map_index_on_dm(DerivedMesh *dm, int from, int index, int index_dmcache, const float fw[4], float UNUSED(foffset), int *mapindex, float mapfw[4])
{
	if (index < 0)
		return 0;

	if (dm->deformedOnly || index_dmcache == DMCACHE_ISCHILD) {
		/* for meshes that are either only deformed or for child particles, the
		 * index and fw do not require any mapping, so we can directly use it */
		if (from == PART_FROM_VERT) {
			if (index >= dm->getNumVerts(dm))
				return 0;

			*mapindex = index;
		}
		else { /* FROM_FACE/FROM_VOLUME */
			if (index >= dm->getNumTessFaces(dm))
				return 0;

			*mapindex = index;
			copy_v4_v4(mapfw, fw);
		}
	}
	else {
		/* for other meshes that have been modified, we try to map the particle
		 * to their new location, which means a different index, and for faces
		 * also a new face interpolation weights */
		if (from == PART_FROM_VERT) {
			if (index_dmcache == DMCACHE_NOTFOUND || index_dmcache > dm->getNumVerts(dm))
				return 0;

			*mapindex = index_dmcache;
		}
		else { /* FROM_FACE/FROM_VOLUME */
			   /* find a face on the derived mesh that uses this face */
			MFace *mface;
			OrigSpaceFace *osface;
			int i;

			i = index_dmcache;

			if (i == DMCACHE_NOTFOUND || i >= dm->getNumTessFaces(dm))
				return 0;

			*mapindex = i;

			/* modify the original weights to become
			 * weights for the derived mesh face */
			osface = dm->getTessFaceDataArray(dm, CD_ORIGSPACE);
			mface = dm->getTessFaceData(dm, i, CD_MFACE);

			if (osface == NULL)
				mapfw[0] = mapfw[1] = mapfw[2] = mapfw[3] = 0.0f;
			else
				psys_origspace_to_w(&osface[i], mface->v4, fw, mapfw);
		}
	}

	return 1;
}

/* interprets particle data to get a point on a mesh in object space */
void psys_particle_on_dm(DerivedMesh *dm, int from, int index, int index_dmcache,
                         const float fw[4], float foffset, float vec[3], float nor[3], float utan[3], float vtan[3],
                         float orco[3], float ornor[3])
{
	float tmpnor[3], mapfw[4];
	float (*orcodata)[3];
	int mapindex;

	if (!psys_map_index_on_dm(dm, from, index, index_dmcache, fw, foffset, &mapindex, mapfw)) {
		if (vec) { vec[0] = vec[1] = vec[2] = 0.0; }
		if (nor) { nor[0] = nor[1] = 0.0; nor[2] = 1.0; }
		if (orco) { orco[0] = orco[1] = orco[2] = 0.0; }
		if (ornor) { ornor[0] = ornor[1] = 0.0; ornor[2] = 1.0; }
		if (utan) { utan[0] = utan[1] = utan[2] = 0.0; }
		if (vtan) { vtan[0] = vtan[1] = vtan[2] = 0.0; }

		return;
	}

	orcodata = dm->getVertDataArray(dm, CD_ORCO);

	if (from == PART_FROM_VERT) {
		dm->getVertCo(dm, mapindex, vec);

		if (nor) {
			dm->getVertNo(dm, mapindex, nor);
			normalize_v3(nor);
		}

		if (orco)
			copy_v3_v3(orco, orcodata[mapindex]);

		if (ornor) {
			dm->getVertNo(dm, mapindex, ornor);
			normalize_v3(ornor);
		}

		if (utan && vtan) {
			utan[0] = utan[1] = utan[2] = 0.0f;
			vtan[0] = vtan[1] = vtan[2] = 0.0f;
		}
	}
	else { /* PART_FROM_FACE / PART_FROM_VOLUME */
		MFace *mface;
		MTFace *mtface;
		MVert *mvert;

		mface = dm->getTessFaceData(dm, mapindex, CD_MFACE);
		mvert = dm->getVertDataArray(dm, CD_MVERT);
		mtface = CustomData_get_layer(&dm->faceData, CD_MTFACE);

		if (mtface)
			mtface += mapindex;

		if (from == PART_FROM_VOLUME) {
			psys_interpolate_face(mvert, mface, mtface, orcodata, mapfw, vec, tmpnor, utan, vtan, orco, ornor);
			if (nor)
				copy_v3_v3(nor, tmpnor);

			normalize_v3(tmpnor);  /* XXX Why not normalize tmpnor before copying it into nor??? -- mont29 */
			mul_v3_fl(tmpnor, -foffset);
			add_v3_v3(vec, tmpnor);
		}
		else
			psys_interpolate_face(mvert, mface, mtface, orcodata, mapfw, vec, nor, utan, vtan, orco, ornor);
	}
}

float psys_particle_value_from_verts(DerivedMesh *dm, short from, ParticleData *pa, float *values)
{
	float mapfw[4];
	int mapindex;

	if (!psys_map_index_on_dm(dm, from, pa->num, pa->num_dmcache, pa->fuv, pa->foffset, &mapindex, mapfw))
		return 0.0f;
	
	return psys_interpolate_value_from_verts(dm, from, mapindex, mapfw, values);
}

ParticleSystemModifierData *psys_get_modifier(Object *ob, ParticleSystem *psys)
{
	ModifierData *md;
	ParticleSystemModifierData *psmd;

	for (md = ob->modifiers.first; md; md = md->next) {
		if (md->type == eModifierType_ParticleSystem) {
			psmd = (ParticleSystemModifierData *) md;
			if (psmd->psys == psys) {
				return psmd;
			}
		}
	}
	return NULL;
}
/************************************************/
/*			Particles on a shape				*/
/************************************************/
/* ready for future use */
static void psys_particle_on_shape(int UNUSED(distr), int UNUSED(index),
                                   float *UNUSED(fuv), float vec[3], float nor[3], float utan[3], float vtan[3],
                                   float orco[3], float ornor[3])
{
	/* TODO */
	float zerovec[3] = {0.0f, 0.0f, 0.0f};
	if (vec) {
		copy_v3_v3(vec, zerovec);
	}
	if (nor) {
		copy_v3_v3(nor, zerovec);
	}
	if (utan) {
		copy_v3_v3(utan, zerovec);
	}
	if (vtan) {
		copy_v3_v3(vtan, zerovec);
	}
	if (orco) {
		copy_v3_v3(orco, zerovec);
	}
	if (ornor) {
		copy_v3_v3(ornor, zerovec);
	}
}
/************************************************/
/*			Particles on emitter				*/
/************************************************/
void psys_particle_on_emitter(ParticleSystemModifierData *psmd, int from, int index, int index_dmcache,
                              float fuv[4], float foffset, float vec[3], float nor[3], float utan[3], float vtan[3],
                              float orco[3], float ornor[3])
{
	if (psmd && psmd->dm) {
		if (psmd->psys->part->distr == PART_DISTR_GRID && psmd->psys->part->from != PART_FROM_VERT) {
			if (vec)
				copy_v3_v3(vec, fuv);

			if (orco)
				copy_v3_v3(orco, fuv);
			return;
		}
		/* we cant use the num_dmcache */
		psys_particle_on_dm(psmd->dm, from, index, index_dmcache, fuv, foffset, vec, nor, utan, vtan, orco, ornor);
	}
	else
		psys_particle_on_shape(from, index, fuv, vec, nor, utan, vtan, orco, ornor);

}
/************************************************/
/*			Path Cache							*/
/************************************************/

static void do_kink(ParticleKey *state, ParticleKey *par, float *par_rot, float time, float freq, float shape, float amplitude, float flat, short type, short axis, float obmat[4][4], int smooth_start)
{
	float kink[3] = {1.f, 0.f, 0.f}, par_vec[3], q1[4] = {1.f, 0.f, 0.f, 0.f};
	float t, dt = 1.f, result[3];

	if (par == NULL || type == PART_KINK_NO)
		return;

	CLAMP(time, 0.f, 1.f);

	if (shape != 0.0f && type != PART_KINK_BRAID) {
		if (shape < 0.0f)
			time = (float)pow(time, 1.f + shape);
		else
			time = (float)pow(time, 1.f / (1.f - shape));
	}

	t = time * freq * (float)M_PI;
	
	if (smooth_start) {
		dt = fabsf(t);
		/* smooth the beginning of kink */
		CLAMP(dt, 0.f, (float)M_PI);
		dt = sinf(dt / 2.f);
	}

	if (type != PART_KINK_RADIAL) {
		float temp[3];

		kink[axis] = 1.f;

		if (obmat)
			mul_mat3_m4_v3(obmat, kink);
		
		if (par_rot)
			mul_qt_v3(par_rot, kink);

		/* make sure kink is normal to strand */
		project_v3_v3v3(temp, kink, par->vel);
		sub_v3_v3(kink, temp);
		normalize_v3(kink);
	}

	copy_v3_v3(result, state->co);
	sub_v3_v3v3(par_vec, par->co, state->co);

	switch (type) {
		case PART_KINK_CURL:
		{
			negate_v3(par_vec);

			if (flat > 0.f) {
				float proj[3];
				project_v3_v3v3(proj, par_vec, par->vel);
				madd_v3_v3fl(par_vec, proj, -flat);

				project_v3_v3v3(proj, par_vec, kink);
				madd_v3_v3fl(par_vec, proj, -flat);
			}

			axis_angle_to_quat(q1, kink, (float)M_PI / 2.f);

			mul_qt_v3(q1, par_vec);

			madd_v3_v3fl(par_vec, kink, amplitude);

			/* rotate kink vector around strand tangent */
			if (t != 0.f) {
				axis_angle_to_quat(q1, par->vel, t);
				mul_qt_v3(q1, par_vec);
			}

			add_v3_v3v3(result, par->co, par_vec);
			break;
		}
		case PART_KINK_RADIAL:
		{
			if (flat > 0.f) {
				float proj[3];
				/* flatten along strand */
				project_v3_v3v3(proj, par_vec, par->vel);
				madd_v3_v3fl(result, proj, flat);
			}

			madd_v3_v3fl(result, par_vec, -amplitude * sinf(t));
			break;
		}
		case PART_KINK_WAVE:
		{
			madd_v3_v3fl(result, kink, amplitude * sinf(t));

			if (flat > 0.f) {
				float proj[3];
				/* flatten along wave */
				project_v3_v3v3(proj, par_vec, kink);
				madd_v3_v3fl(result, proj, flat);

				/* flatten along strand */
				project_v3_v3v3(proj, par_vec, par->vel);
				madd_v3_v3fl(result, proj, flat);
			}
			break;
		}
		case PART_KINK_BRAID:
		{
			float y_vec[3] = {0.f, 1.f, 0.f};
			float z_vec[3] = {0.f, 0.f, 1.f};
			float vec_one[3], state_co[3];
			float inp_y, inp_z, length;
		
			if (par_rot) {
				mul_qt_v3(par_rot, y_vec);
				mul_qt_v3(par_rot, z_vec);
			}

			negate_v3(par_vec);
			normalize_v3_v3(vec_one, par_vec);

			inp_y = dot_v3v3(y_vec, vec_one);
			inp_z = dot_v3v3(z_vec, vec_one);

			if (inp_y > 0.5f) {
				copy_v3_v3(state_co, y_vec);

				mul_v3_fl(y_vec, amplitude * cosf(t));
				mul_v3_fl(z_vec, amplitude / 2.f * sinf(2.f * t));
			}
			else if (inp_z > 0.0f) {
				mul_v3_v3fl(state_co, z_vec, sinf((float)M_PI / 3.f));
				madd_v3_v3fl(state_co, y_vec, -0.5f);

				mul_v3_fl(y_vec, -amplitude * cosf(t + (float)M_PI / 3.f));
				mul_v3_fl(z_vec, amplitude / 2.f * cosf(2.f * t + (float)M_PI / 6.f));
			}
			else {
				mul_v3_v3fl(state_co, z_vec, -sinf((float)M_PI / 3.f));
				madd_v3_v3fl(state_co, y_vec, -0.5f);

				mul_v3_fl(y_vec, amplitude * -sinf(t + (float)M_PI / 6.f));
				mul_v3_fl(z_vec, amplitude / 2.f * -sinf(2.f * t + (float)M_PI / 3.f));
			}

			mul_v3_fl(state_co, amplitude);
			add_v3_v3(state_co, par->co);
			sub_v3_v3v3(par_vec, state->co, state_co);

			length = normalize_v3(par_vec);
			mul_v3_fl(par_vec, MIN2(length, amplitude / 2.f));

			add_v3_v3v3(state_co, par->co, y_vec);
			add_v3_v3(state_co, z_vec);
			add_v3_v3(state_co, par_vec);

			shape = 2.f * (float)M_PI * (1.f + shape);

			if (t < shape) {
				shape = t / shape;
				shape = (float)sqrt((double)shape);
				interp_v3_v3v3(result, result, state_co, shape);
			}
			else {
				copy_v3_v3(result, state_co);
			}
			break;
		}
	}

	/* blend the start of the kink */
	if (dt < 1.f)
		interp_v3_v3v3(state->co, state->co, result, dt);
	else
		copy_v3_v3(state->co, result);
}

static float do_clump(ParticleKey *state, ParticleKey *par, float time, float clumpfac, float clumppow, float pa_clump)
{
	float clump = 0.f;

	if (par && clumpfac != 0.0f) {
		float cpow;

		if (clumppow < 0.0f)
			cpow = 1.0f + clumppow;
		else
			cpow = 1.0f + 9.0f * clumppow;

		if (clumpfac < 0.0f) /* clump roots instead of tips */
			clump = -clumpfac * pa_clump * (float)pow(1.0 - (double)time, (double)cpow);
		else
			clump = clumpfac * pa_clump * (float)pow((double)time, (double)cpow);

		interp_v3_v3v3(state->co, state->co, par->co, clump);
	}

	return clump;
}
void precalc_guides(ParticleSimulationData *sim, ListBase *effectors)
{
	EffectedPoint point;
	ParticleKey state;
	EffectorData efd;
	EffectorCache *eff;
	ParticleSystem *psys = sim->psys;
	EffectorWeights *weights = sim->psys->part->effector_weights;
	GuideEffectorData *data;
	PARTICLE_P;

	if (!effectors)
		return;

	LOOP_PARTICLES {
		psys_particle_on_emitter(sim->psmd, sim->psys->part->from, pa->num, pa->num_dmcache, pa->fuv, pa->foffset, state.co, 0, 0, 0, 0, 0);
		
		mul_m4_v3(sim->ob->obmat, state.co);
		mul_mat3_m4_v3(sim->ob->obmat, state.vel);
		
		pd_point_from_particle(sim, pa, &state, &point);

		for (eff = effectors->first; eff; eff = eff->next) {
			if (eff->pd->forcefield != PFIELD_GUIDE)
				continue;

			if (!eff->guide_data)
				eff->guide_data = MEM_callocN(sizeof(GuideEffectorData) * psys->totpart, "GuideEffectorData");

			data = eff->guide_data + p;

			sub_v3_v3v3(efd.vec_to_point, state.co, eff->guide_loc);
			copy_v3_v3(efd.nor, eff->guide_dir);
			efd.distance = len_v3(efd.vec_to_point);

			copy_v3_v3(data->vec_to_point, efd.vec_to_point);
			data->strength = effector_falloff(eff, &efd, &point, weights);
		}
	}
}
int do_guides(ListBase *effectors, ParticleKey *state, int index, float time)
{
	EffectorCache *eff;
	PartDeflect *pd;
	Curve *cu;
	ParticleKey key, par;
	GuideEffectorData *data;

	float effect[3] = {0.0f, 0.0f, 0.0f}, veffect[3] = {0.0f, 0.0f, 0.0f};
	float guidevec[4], guidedir[3], rot2[4], temp[3];
	float guidetime, radius, weight, angle, totstrength = 0.0f;
	float vec_to_point[3];

	if (effectors) for (eff = effectors->first; eff; eff = eff->next) {
			pd = eff->pd;

			if (pd->forcefield != PFIELD_GUIDE)
				continue;

			data = eff->guide_data + index;

			if (data->strength <= 0.0f)
				continue;

			guidetime = time / (1.0f - pd->free_end);

			if (guidetime > 1.0f)
				continue;

			cu = (Curve *)eff->ob->data;

			if (pd->flag & PFIELD_GUIDE_PATH_ADD) {
				if (where_on_path(eff->ob, data->strength * guidetime, guidevec, guidedir, NULL, &radius, &weight) == 0)
					return 0;
			}
			else {
				if (where_on_path(eff->ob, guidetime, guidevec, guidedir, NULL, &radius, &weight) == 0)
					return 0;
			}

			mul_m4_v3(eff->ob->obmat, guidevec);
			mul_mat3_m4_v3(eff->ob->obmat, guidedir);

			normalize_v3(guidedir);

			copy_v3_v3(vec_to_point, data->vec_to_point);

			if (guidetime != 0.0f) {
				/* curve direction */
				cross_v3_v3v3(temp, eff->guide_dir, guidedir);
				angle = dot_v3v3(eff->guide_dir, guidedir) / (len_v3(eff->guide_dir));
				angle = saacos(angle);
				axis_angle_to_quat(rot2, temp, angle);
				mul_qt_v3(rot2, vec_to_point);

				/* curve tilt */
				axis_angle_to_quat(rot2, guidedir, guidevec[3] - eff->guide_loc[3]);
				mul_qt_v3(rot2, vec_to_point);
			}

			/* curve taper */
			if (cu->taperobj)
				mul_v3_fl(vec_to_point, BKE_displist_calc_taper(eff->scene, cu->taperobj, (int)(data->strength * guidetime * 100.0f), 100));

			else { /* curve size*/
				if (cu->flag & CU_PATH_RADIUS) {
					mul_v3_fl(vec_to_point, radius);
				}
			}
			par.co[0] = par.co[1] = par.co[2] = 0.0f;
			copy_v3_v3(key.co, vec_to_point);
			do_kink(&key, &par, 0, guidetime, pd->kink_freq, pd->kink_shape, pd->kink_amp, 0.f, pd->kink, pd->kink_axis, 0, 0);
			do_clump(&key, &par, guidetime, pd->clump_fac, pd->clump_pow, 1.0f);
			copy_v3_v3(vec_to_point, key.co);

			add_v3_v3(vec_to_point, guidevec);

			//sub_v3_v3v3(pa_loc, pa_loc, pa_zero);
			madd_v3_v3fl(effect, vec_to_point, data->strength);
			madd_v3_v3fl(veffect, guidedir, data->strength);
			totstrength += data->strength;

			if (pd->flag & PFIELD_GUIDE_PATH_WEIGHT)
				totstrength *= weight;
		}

	if (totstrength != 0.0f) {
		if (totstrength > 1.0f)
			mul_v3_fl(effect, 1.0f / totstrength);
		CLAMP(totstrength, 0.0f, 1.0f);
		//add_v3_v3(effect, pa_zero);
		interp_v3_v3v3(state->co, state->co, effect, totstrength);

		normalize_v3(veffect);
		mul_v3_fl(veffect, len_v3(state->vel));
		copy_v3_v3(state->vel, veffect);
		return 1;
	}
	return 0;
}
static void do_rough(float *loc, float mat[4][4], float t, float fac, float size, float thres, ParticleKey *state)
{
	float rough[3];
	float rco[3];

	if (thres != 0.0f) {
		if (fabsf((float)(-1.5f + loc[0] + loc[1] + loc[2])) < 1.5f * thres) {
			return;
		}
	}

	copy_v3_v3(rco, loc);
	mul_v3_fl(rco, t);
	rough[0] = -1.0f + 2.0f * BLI_gTurbulence(size, rco[0], rco[1], rco[2], 2, 0, 2);
	rough[1] = -1.0f + 2.0f * BLI_gTurbulence(size, rco[1], rco[2], rco[0], 2, 0, 2);
	rough[2] = -1.0f + 2.0f * BLI_gTurbulence(size, rco[2], rco[0], rco[1], 2, 0, 2);

	madd_v3_v3fl(state->co, mat[0], fac * rough[0]);
	madd_v3_v3fl(state->co, mat[1], fac * rough[1]);
	madd_v3_v3fl(state->co, mat[2], fac * rough[2]);
}
static void do_rough_end(float *loc, float mat[4][4], float t, float fac, float shape, ParticleKey *state)
{
	float rough[2];
	float roughfac;

	roughfac = fac * (float)pow((double)t, shape);
	copy_v2_v2(rough, loc);
	rough[0] = -1.0f + 2.0f * rough[0];
	rough[1] = -1.0f + 2.0f * rough[1];
	mul_v2_fl(rough, roughfac);

	madd_v3_v3fl(state->co, mat[0], rough[0]);
	madd_v3_v3fl(state->co, mat[1], rough[1]);
}
static void do_path_effectors(ParticleSimulationData *sim, int i, ParticleCacheKey *ca, int k, int steps, float *UNUSED(rootco), float effector, float UNUSED(dfra), float UNUSED(cfra), float *length, float *vec)
{
	float force[3] = {0.0f, 0.0f, 0.0f};
	ParticleKey eff_key;
	EffectedPoint epoint;

	/* Don't apply effectors for dynamic hair, otherwise the effectors don't get applied twice. */
	if (sim->psys->flag & PSYS_HAIR_DYNAMICS)
		return;

	copy_v3_v3(eff_key.co, (ca - 1)->co);
	copy_v3_v3(eff_key.vel, (ca - 1)->vel);
	copy_qt_qt(eff_key.rot, (ca - 1)->rot);

	pd_point_from_particle(sim, sim->psys->particles + i, &eff_key, &epoint);
	pdDoEffectors(sim->psys->effectors, sim->colliders, sim->psys->part->effector_weights, &epoint, force, NULL);

	mul_v3_fl(force, effector * powf((float)k / (float)steps, 100.0f * sim->psys->part->eff_hair) / (float)steps);

	add_v3_v3(force, vec);

	normalize_v3(force);

	if (k < steps)
		sub_v3_v3v3(vec, (ca + 1)->co, ca->co);

	madd_v3_v3v3fl(ca->co, (ca - 1)->co, force, *length);

	if (k < steps)
		*length = len_v3(vec);
}
static int check_path_length(int k, ParticleCacheKey *keys, ParticleCacheKey *state, float max_length, float *cur_length, float length, float *dvec)
{
	if (*cur_length + length > max_length) {
		mul_v3_fl(dvec, (max_length - *cur_length) / length);
		add_v3_v3v3(state->co, (state - 1)->co, dvec);
		keys->steps = k;
		/* something over the maximum step value */
		return k = 100000;
	}
	else {
		*cur_length += length;
		return k;
	}
}
static void offset_child(ChildParticle *cpa, ParticleKey *par, float *par_rot, ParticleKey *child, float flat, float radius)
{
	copy_v3_v3(child->co, cpa->fuv);
	mul_v3_fl(child->co, radius);

	child->co[0] *= flat;

	copy_v3_v3(child->vel, par->vel);

	if (par_rot) {
		mul_qt_v3(par_rot, child->co);
		copy_qt_qt(child->rot, par_rot);
	}
	else
		unit_qt(child->rot);

	add_v3_v3(child->co, par->co);
}
float *psys_cache_vgroup(DerivedMesh *dm, ParticleSystem *psys, int vgroup)
{
	float *vg = 0;

	if (vgroup < 0) {
		/* hair dynamics pinning vgroup */

	}
	else if (psys->vgroup[vgroup]) {
		MDeformVert *dvert = dm->getVertDataArray(dm, CD_MDEFORMVERT);
		if (dvert) {
			int totvert = dm->getNumVerts(dm), i;
			vg = MEM_callocN(sizeof(float) * totvert, "vg_cache");
			if (psys->vg_neg & (1 << vgroup)) {
				for (i = 0; i < totvert; i++)
					vg[i] = 1.0f - defvert_find_weight(&dvert[i], psys->vgroup[vgroup] - 1);
			}
			else {
				for (i = 0; i < totvert; i++)
					vg[i] =  defvert_find_weight(&dvert[i], psys->vgroup[vgroup] - 1);
			}
		}
	}
	return vg;
}
void psys_find_parents(ParticleSimulationData *sim)
{
	ParticleSettings *part = sim->psys->part;
	KDTree *tree;
	ChildParticle *cpa;
	int p, totparent, totchild = sim->psys->totchild;
	float co[3], orco[3];
	int from = PART_FROM_FACE;
	totparent = (int)(totchild * part->parents * 0.3f);

	if ((sim->psys->renderdata || G.is_rendering) && part->child_nbr && part->ren_child_nbr)
		totparent *= (float)part->child_nbr / (float)part->ren_child_nbr;

	/* hard limit, workaround for it being ignored above */
	if (sim->psys->totpart < totparent) {
		totparent = sim->psys->totpart;
	}

	tree = BLI_kdtree_new(totparent);

	for (p = 0, cpa = sim->psys->child; p < totparent; p++, cpa++) {
		psys_particle_on_emitter(sim->psmd, from, cpa->num, DMCACHE_ISCHILD, cpa->fuv, cpa->foffset, co, 0, 0, 0, orco, 0);
		BLI_kdtree_insert(tree, p, orco);
	}

	BLI_kdtree_balance(tree);

	for (; p < totchild; p++, cpa++) {
		psys_particle_on_emitter(sim->psmd, from, cpa->num, DMCACHE_ISCHILD, cpa->fuv, cpa->foffset, co, 0, 0, 0, orco, 0);
		cpa->parent = BLI_kdtree_find_nearest(tree, orco, NULL);
	}

	BLI_kdtree_free(tree);
}

static void get_strand_normal(Material *ma, const float surfnor[3], float surfdist, float nor[3])
{
	float cross[3], nstrand[3], vnor[3], blend;

	if (!((ma->mode & MA_STR_SURFDIFF) || (ma->strand_surfnor > 0.0f)))
		return;

	if (ma->mode & MA_STR_SURFDIFF) {
		cross_v3_v3v3(cross, surfnor, nor);
		cross_v3_v3v3(nstrand, nor, cross);

		blend = dot_v3v3(nstrand, surfnor);
		CLAMP(blend, 0.0f, 1.0f);

		interp_v3_v3v3(vnor, nstrand, surfnor, blend);
		normalize_v3(vnor);
	}
	else {
		copy_v3_v3(vnor, nor);
	}
	
	if (ma->strand_surfnor > 0.0f) {
		if (ma->strand_surfnor > surfdist) {
			blend = (ma->strand_surfnor - surfdist) / ma->strand_surfnor;
			interp_v3_v3v3(vnor, vnor, surfnor, blend);
			normalize_v3(vnor);
		}
	}

	copy_v3_v3(nor, vnor);
}

static int psys_threads_init_path(ParticleThread *threads, Scene *scene, float cfra, int editupdate)
{
	ParticleThreadContext *ctx = threads[0].ctx;
/*	Object *ob = ctx->sim.ob; */
	ParticleSystem *psys = ctx->sim.psys;
	ParticleSettings *part = psys->part;
/*	ParticleEditSettings *pset = &scene->toolsettings->particle; */
	int totparent = 0, between = 0;
	int steps = (int)pow(2.0, (double)part->draw_step);
	int totchild = psys->totchild;
	int i, seed, totthread = threads[0].tot;

	/*---start figuring out what is actually wanted---*/
	if (psys_in_edit_mode(scene, psys)) {
		ParticleEditSettings *pset = &scene->toolsettings->particle;

		if (psys->renderdata == 0 && (psys->edit == NULL || pset->flag & PE_DRAW_PART) == 0)
			totchild = 0;

		steps = (int)pow(2.0, (double)pset->draw_step);
	}

	if (totchild && part->childtype == PART_CHILD_FACES) {
		totparent = (int)(totchild * part->parents * 0.3f);
		
		if ((psys->renderdata || G.is_rendering) && part->child_nbr && part->ren_child_nbr)
			totparent *= (float)part->child_nbr / (float)part->ren_child_nbr;

		/* part->parents could still be 0 so we can't test with totparent */
		between = 1;
	}

	if (psys->renderdata)
		steps = (int)pow(2.0, (double)part->ren_step);
	else {
		totchild = (int)((float)totchild * (float)part->disp / 100.0f);
		totparent = MIN2(totparent, totchild);
	}

	if (totchild == 0) return 0;

	/* init random number generator */
	seed = 31415926 + ctx->sim.psys->seed;
	
	if (ctx->editupdate || totchild < 10000)
		totthread = 1;
	
	for (i = 0; i < totthread; i++) {
		threads[i].rng_path = BLI_rng_new(seed);
		threads[i].tot = totthread;
	}

	/* fill context values */
	ctx->between = between;
	ctx->steps = steps;
	ctx->totchild = totchild;
	ctx->totparent = totparent;
	ctx->parent_pass = 0;
	ctx->cfra = cfra;
	ctx->editupdate = editupdate;

	psys->lattice_deform_data = psys_create_lattice_deform_data(&ctx->sim);

	/* cache all relevant vertex groups if they exist */
	ctx->vg_length = psys_cache_vgroup(ctx->dm, psys, PSYS_VG_LENGTH);
	ctx->vg_clump = psys_cache_vgroup(ctx->dm, psys, PSYS_VG_CLUMP);
	ctx->vg_kink = psys_cache_vgroup(ctx->dm, psys, PSYS_VG_KINK);
	ctx->vg_rough1 = psys_cache_vgroup(ctx->dm, psys, PSYS_VG_ROUGH1);
	ctx->vg_rough2 = psys_cache_vgroup(ctx->dm, psys, PSYS_VG_ROUGH2);
	ctx->vg_roughe = psys_cache_vgroup(ctx->dm, psys, PSYS_VG_ROUGHE);
	if (psys->part->flag & PART_CHILD_EFFECT)
		ctx->vg_effector = psys_cache_vgroup(ctx->dm, psys, PSYS_VG_EFFECTOR);

	/* set correct ipo timing */
#if 0 // XXX old animation system
	if (part->flag & PART_ABS_TIME && part->ipo) {
		calc_ipo(part->ipo, cfra);
		execute_ipo((ID *)part, part->ipo);
	}
#endif // XXX old animation system

	return 1;
}

/* note: this function must be thread safe, except for branching! */
static void psys_thread_create_path(ParticleThread *thread, struct ChildParticle *cpa, ParticleCacheKey *child_keys, int i)
{
	ParticleThreadContext *ctx = thread->ctx;
	Object *ob = ctx->sim.ob;
	ParticleSystem *psys = ctx->sim.psys;
	ParticleSettings *part = psys->part;
	ParticleCacheKey **cache = psys->childcache;
	ParticleCacheKey **pcache = psys_in_edit_mode(ctx->sim.scene, psys) ? psys->edit->pathcache : psys->pathcache;
	ParticleCacheKey *child, *par = NULL, *key[4];
	ParticleTexture ptex;
	float *cpa_fuv = 0, *par_rot = 0, rot[4];
	float orco[3], ornor[3], hairmat[4][4], t, dvec[3], off1[4][3], off2[4][3];
	float length, max_length = 1.0f, cur_length = 0.0f;
	float eff_length, eff_vec[3], weight[4];
	int k, cpa_num;
	short cpa_from;

	if (!pcache)
		return;

	if (ctx->between) {
		ParticleData *pa = psys->particles + cpa->pa[0];
		int w, needupdate;
		float foffset, wsum = 0.f;
		float co[3];
		float p_min = part->parting_min;
		float p_max = part->parting_max;
		/* Virtual parents don't work nicely with parting. */
		float p_fac = part->parents > 0.f ? 0.f : part->parting_fac;

		if (ctx->editupdate) {
			needupdate = 0;
			w = 0;
			while (w < 4 && cpa->pa[w] >= 0) {
				if (psys->edit->points[cpa->pa[w]].flag & PEP_EDIT_RECALC) {
					needupdate = 1;
					break;
				}
				w++;
			}

			if (!needupdate)
				return;
			else
				memset(child_keys, 0, sizeof(*child_keys) * (ctx->steps + 1));
		}

		/* get parent paths */
		for (w = 0; w < 4; w++) {
			if (cpa->pa[w] >= 0) {
				key[w] = pcache[cpa->pa[w]];
				weight[w] = cpa->w[w];
			}
			else {
				key[w] = pcache[0];
				weight[w] = 0.f;
			}
		}

		/* modify weights to create parting */
		if (p_fac > 0.f) {
			for (w = 0; w < 4; w++) {
				if (w && weight[w] > 0.f) {
					float d;
					if (part->flag & PART_CHILD_LONG_HAIR) {
						/* For long hair use tip distance/root distance as parting factor instead of root to tip angle. */
						float d1 = len_v3v3(key[0]->co, key[w]->co);
						float d2 = len_v3v3((key[0] + key[0]->steps - 1)->co, (key[w] + key[w]->steps - 1)->co);

						d = d1 > 0.f ? d2 / d1 - 1.f : 10000.f;
					}
					else {
						float v1[3], v2[3];
						sub_v3_v3v3(v1, (key[0] + key[0]->steps - 1)->co, key[0]->co);
						sub_v3_v3v3(v2, (key[w] + key[w]->steps - 1)->co, key[w]->co);
						normalize_v3(v1);
						normalize_v3(v2);

						d = RAD2DEGF(saacos(dot_v3v3(v1, v2)));
					}

					if (p_max > p_min)
						d = (d - p_min) / (p_max - p_min);
					else
						d = (d - p_min) <= 0.f ? 0.f : 1.f;

					CLAMP(d, 0.f, 1.f);

					if (d > 0.f)
						weight[w] *= (1.f - d);
				}
				wsum += weight[w];
			}
			for (w = 0; w < 4; w++)
				weight[w] /= wsum;

			interp_v4_v4v4(weight, cpa->w, weight, p_fac);
		}

		/* get the original coordinates (orco) for texture usage */
		cpa_num = cpa->num;
		
		foffset = cpa->foffset;
		cpa_fuv = cpa->fuv;
		cpa_from = PART_FROM_FACE;

		psys_particle_on_emitter(ctx->sim.psmd, cpa_from, cpa_num, DMCACHE_ISCHILD, cpa->fuv, foffset, co, ornor, 0, 0, orco, 0);

		mul_m4_v3(ob->obmat, co);

		for (w = 0; w < 4; w++)
			sub_v3_v3v3(off1[w], co, key[w]->co);

		psys_mat_hair_to_global(ob, ctx->sim.psmd->dm, psys->part->from, pa, hairmat);
	}
	else {
		ParticleData *pa = psys->particles + cpa->parent;
		float co[3];
		if (ctx->editupdate) {
			if (!(psys->edit->points[cpa->parent].flag & PEP_EDIT_RECALC))
				return;

			memset(child_keys, 0, sizeof(*child_keys) * (ctx->steps + 1));
		}

		/* get the parent path */
		key[0] = pcache[cpa->parent];

		/* get the original coordinates (orco) for texture usage */
		cpa_from = part->from;
		cpa_num = pa->num;
		/* XXX hack to avoid messed up particle num and subsequent crash (#40733) */
		if (cpa_num > ctx->sim.psmd->dm->getNumTessFaces(ctx->sim.psmd->dm))
			cpa_num = 0;
		cpa_fuv = pa->fuv;

		psys_particle_on_emitter(ctx->sim.psmd, cpa_from, cpa_num, DMCACHE_ISCHILD, cpa_fuv, pa->foffset, co, ornor, 0, 0, orco, 0);

		psys_mat_hair_to_global(ob, ctx->sim.psmd->dm, psys->part->from, pa, hairmat);
	}

	child_keys->steps = ctx->steps;

	/* get different child parameters from textures & vgroups */
	get_child_modifier_parameters(part, ctx, cpa, cpa_from, cpa_num, cpa_fuv, orco, &ptex);

	if (ptex.exist < psys_frand(psys, i + 24)) {
		child_keys->steps = -1;
		return;
	}

	/* create the child path */
	for (k = 0, child = child_keys; k <= ctx->steps; k++, child++) {
		if (ctx->between) {
			int w = 0;

			zero_v3(child->co);
			zero_v3(child->vel);
			unit_qt(child->rot);

			for (w = 0; w < 4; w++) {
				copy_v3_v3(off2[w], off1[w]);

				if (part->flag & PART_CHILD_LONG_HAIR) {
					/* Use parent rotation (in addition to emission location) to determine child offset. */
					if (k)
						mul_qt_v3((key[w] + k)->rot, off2[w]);

					/* Fade the effect of rotation for even lengths in the end */
					project_v3_v3v3(dvec, off2[w], (key[w] + k)->vel);
					madd_v3_v3fl(off2[w], dvec, -(float)k / (float)ctx->steps);
				}

				add_v3_v3(off2[w], (key[w] + k)->co);
			}

			/* child position is the weighted sum of parent positions */
			interp_v3_v3v3v3v3(child->co, off2[0], off2[1], off2[2], off2[3], weight);
			interp_v3_v3v3v3v3(child->vel, (key[0] + k)->vel, (key[1] + k)->vel, (key[2] + k)->vel, (key[3] + k)->vel, weight);

			copy_qt_qt(child->rot, (key[0] + k)->rot);
		}
		else {
			if (k) {
				mul_qt_qtqt(rot, (key[0] + k)->rot, key[0]->rot);
				par_rot = rot;
			}
			else {
				par_rot = key[0]->rot;
			}
			/* offset the child from the parent position */
			offset_child(cpa, (ParticleKey *)(key[0] + k), par_rot, (ParticleKey *)child, part->childflat, part->childrad);
		}

		child->time = (float)k / (float)ctx->steps;
	}

	/* apply effectors */
	if (part->flag & PART_CHILD_EFFECT) {
		for (k = 0, child = child_keys; k <= ctx->steps; k++, child++) {
			if (k) {
				do_path_effectors(&ctx->sim, cpa->pa[0], child, k, ctx->steps, child_keys->co, ptex.effector, 0.0f, ctx->cfra, &eff_length, eff_vec);
			}
			else {
				sub_v3_v3v3(eff_vec, (child + 1)->co, child->co);
				eff_length = len_v3(eff_vec);
			}
		}
	}

	for (k = 0, child = child_keys; k <= ctx->steps; k++, child++) {
		t = (float)k / (float)ctx->steps;

		if (ctx->totparent)
			/* this is now threadsafe, virtual parents are calculated before rest of children */
			par = (i >= ctx->totparent) ? cache[cpa->parent] : NULL;
		else if (cpa->parent >= 0)
			par = pcache[cpa->parent];

		if (par) {
			if (k) {
				mul_qt_qtqt(rot, (par + k)->rot, par->rot);
				par_rot = rot;
			}
			else {
				par_rot = par->rot;
			}
			par += k;
		}

		/* apply different deformations to the child path */
		do_child_modifiers(&ctx->sim, &ptex, (ParticleKey *)par, par_rot, cpa, orco, hairmat, (ParticleKey *)child, t);

		/* we have to correct velocity because of kink & clump */
		if (k > 1) {
			sub_v3_v3v3((child - 1)->vel, child->co, (child - 2)->co);
			mul_v3_fl((child - 1)->vel, 0.5);

			if (ctx->ma && (part->draw_col == PART_DRAW_COL_MAT))
				get_strand_normal(ctx->ma, ornor, cur_length, (child - 1)->vel);
		}

		if (k == ctx->steps)
			sub_v3_v3v3(child->vel, child->co, (child - 1)->co);

		/* check if path needs to be cut before actual end of data points */
		if (k) {
			sub_v3_v3v3(dvec, child->co, (child - 1)->co);
			length = 1.0f / (float)ctx->steps;
			k = check_path_length(k, child_keys, child, max_length, &cur_length, length, dvec);
		}
		else {
			/* initialize length calculation */
			max_length = ptex.length;
			cur_length = 0.0f;
		}

		if (ctx->ma && (part->draw_col == PART_DRAW_COL_MAT)) {
			copy_v3_v3(child->col, &ctx->ma->r);
			get_strand_normal(ctx->ma, ornor, cur_length, child->vel);
		}
	}

	/* Hide virtual parents */
	if (i < ctx->totparent)
		child_keys->steps = -1;
}

static void *exec_child_path_cache(void *data)
{
	ParticleThread *thread = (ParticleThread *)data;
	ParticleThreadContext *ctx = thread->ctx;
	ParticleSystem *psys = ctx->sim.psys;
	ParticleCacheKey **cache = psys->childcache;
	ChildParticle *cpa;
	int i, totchild = ctx->totchild, first = 0;

	if (thread->tot > 1) {
		first = ctx->parent_pass ? 0 : ctx->totparent;
		totchild = ctx->parent_pass ? ctx->totparent : ctx->totchild;
	}
	
	cpa = psys->child + first + thread->num;
	for (i = first + thread->num; i < totchild; i += thread->tot, cpa += thread->tot)
		psys_thread_create_path(thread, cpa, cache[i], i);

	return 0;
}

void psys_cache_child_paths(ParticleSimulationData *sim, float cfra, int editupdate)
{
	ParticleThread *pthreads;
	ParticleThreadContext *ctx;
	ListBase threads;
	int i, totchild, totparent, totthread;

	if (sim->psys->flag & PSYS_GLOBAL_HAIR)
		return;

	pthreads = psys_threads_create(sim);

	if (!psys_threads_init_path(pthreads, sim->scene, cfra, editupdate)) {
		psys_threads_free(pthreads);
		return;
	}

	ctx = pthreads[0].ctx;
	totchild = ctx->totchild;
	totparent = ctx->totparent;

	if (editupdate && sim->psys->childcache && totchild == sim->psys->totchildcache) {
		; /* just overwrite the existing cache */
	}
	else {
		/* clear out old and create new empty path cache */
		free_child_path_cache(sim->psys);
		sim->psys->childcache = psys_alloc_path_cache_buffers(&sim->psys->childcachebufs, totchild, ctx->steps + 1);
		sim->psys->totchildcache = totchild;
	}

	totthread = pthreads[0].tot;

	if (totthread > 1) {

		/* make virtual child parents thread safe by calculating them first */
		if (totparent) {
			BLI_init_threads(&threads, exec_child_path_cache, totthread);
			
			for (i = 0; i < totthread; i++) {
				pthreads[i].ctx->parent_pass = 1;
				BLI_insert_thread(&threads, &pthreads[i]);
			}

			BLI_end_threads(&threads);

			for (i = 0; i < totthread; i++)
				pthreads[i].ctx->parent_pass = 0;
		}

		BLI_init_threads(&threads, exec_child_path_cache, totthread);

		for (i = 0; i < totthread; i++)
			BLI_insert_thread(&threads, &pthreads[i]);

		BLI_end_threads(&threads);
	}
	else
		exec_child_path_cache(&pthreads[0]);

	psys_threads_free(pthreads);
}
/* figure out incremental rotations along path starting from unit quat */
static void cache_key_incremental_rotation(ParticleCacheKey *key0, ParticleCacheKey *key1, ParticleCacheKey *key2, float *prev_tangent, int i)
{
	float cosangle, angle, tangent[3], normal[3], q[4];

	switch (i) {
		case 0:
			/* start from second key */
			break;
		case 1:
			/* calculate initial tangent for incremental rotations */
			sub_v3_v3v3(prev_tangent, key0->co, key1->co);
			normalize_v3(prev_tangent);
			unit_qt(key1->rot);
			break;
		default:
			sub_v3_v3v3(tangent, key0->co, key1->co);
			normalize_v3(tangent);

			cosangle = dot_v3v3(tangent, prev_tangent);

			/* note we do the comparison on cosangle instead of
			 * angle, since floating point accuracy makes it give
			 * different results across platforms */
			if (cosangle > 0.999999f) {
				copy_v4_v4(key1->rot, key2->rot);
			}
			else {
				angle = saacos(cosangle);
				cross_v3_v3v3(normal, prev_tangent, tangent);
				axis_angle_to_quat(q, normal, angle);
				mul_qt_qtqt(key1->rot, q, key2->rot);
			}

			copy_v3_v3(prev_tangent, tangent);
	}
}

/**
 * Calculates paths ready for drawing/rendering
 * - Useful for making use of opengl vertex arrays for super fast strand drawing.
 * - Makes child strands possible and creates them too into the cache.
 * - Cached path data is also used to determine cut position for the editmode tool. */
void psys_cache_paths(ParticleSimulationData *sim, float cfra)
{
	PARTICLE_PSMD;
	ParticleEditSettings *pset = &sim->scene->toolsettings->particle;
	ParticleSystem *psys = sim->psys;
	ParticleSettings *part = psys->part;
	ParticleCacheKey *ca, **cache;

	DerivedMesh *hair_dm = (psys->part->type == PART_HAIR && psys->flag & PSYS_HAIR_DYNAMICS) ? psys->hair_out_dm : NULL;
	
	ParticleKey result;
	
	Material *ma;
	ParticleInterpolationData pind;
	ParticleTexture ptex;

	PARTICLE_P;
	
	float birthtime = 0.0, dietime = 0.0;
	float t, time = 0.0, dfra = 1.0 /* , frs_sec = sim->scene->r.frs_sec*/ /*UNUSED*/;
	float col[4] = {0.5f, 0.5f, 0.5f, 1.0f};
	float prev_tangent[3] = {0.0f, 0.0f, 0.0f}, hairmat[4][4];
	float rotmat[3][3];
	int k;
	int steps = (int)pow(2.0, (double)(psys->renderdata ? part->ren_step : part->draw_step));
	int totpart = psys->totpart;
	float length, vec[3];
	float *vg_effector = NULL;
	float *vg_length = NULL, pa_length = 1.0f;
	int keyed, baked;

	/* we don't have anything valid to create paths from so let's quit here */
	if ((psys->flag & PSYS_HAIR_DONE || psys->flag & PSYS_KEYED || psys->pointcache) == 0)
		return;

	if (psys_in_edit_mode(sim->scene, psys))
		if (psys->renderdata == 0 && (psys->edit == NULL || pset->flag & PE_DRAW_PART) == 0)
			return;

	keyed = psys->flag & PSYS_KEYED;
	baked = psys->pointcache->mem_cache.first && psys->part->type != PART_HAIR;

	/* clear out old and create new empty path cache */
	psys_free_path_cache(psys, psys->edit);
	cache = psys->pathcache = psys_alloc_path_cache_buffers(&psys->pathcachebufs, totpart, steps + 1);

	psys->lattice_deform_data = psys_create_lattice_deform_data(sim);
	ma = give_current_material(sim->ob, psys->part->omat);
	if (ma && (psys->part->draw_col == PART_DRAW_COL_MAT))
		copy_v3_v3(col, &ma->r);

	if ((psys->flag & PSYS_GLOBAL_HAIR) == 0) {
		if ((psys->part->flag & PART_CHILD_EFFECT) == 0)
			vg_effector = psys_cache_vgroup(psmd->dm, psys, PSYS_VG_EFFECTOR);
		
		if (!psys->totchild)
			vg_length = psys_cache_vgroup(psmd->dm, psys, PSYS_VG_LENGTH);
	}

	/* ensure we have tessfaces to be used for mapping */
	if (part->from != PART_FROM_VERT) {
		DM_ensure_tessface(psmd->dm);
	}

	/*---first main loop: create all actual particles' paths---*/
	LOOP_SHOWN_PARTICLES {
		if (!psys->totchild) {
			psys_get_texture(sim, pa, &ptex, PAMAP_LENGTH, 0.f);
			pa_length = ptex.length * (1.0f - part->randlength * psys_frand(psys, psys->seed + p));
			if (vg_length)
				pa_length *= psys_particle_value_from_verts(psmd->dm, part->from, pa, vg_length);
		}

		pind.keyed = keyed;
		pind.cache = baked ? psys->pointcache : NULL;
		pind.epoint = NULL;
		pind.bspline = (psys->part->flag & PART_HAIR_BSPLINE);
		pind.dm = hair_dm;

		memset(cache[p], 0, sizeof(*cache[p]) * (steps + 1));

		cache[p]->steps = steps;

		/*--get the first data points--*/
		init_particle_interpolation(sim->ob, sim->psys, pa, &pind);

		/* hairmat is needed for for non-hair particle too so we get proper rotations */
		psys_mat_hair_to_global(sim->ob, psmd->dm, psys->part->from, pa, hairmat);
		copy_v3_v3(rotmat[0], hairmat[2]);
		copy_v3_v3(rotmat[1], hairmat[1]);
		copy_v3_v3(rotmat[2], hairmat[0]);

		if (part->draw & PART_ABS_PATH_TIME) {
			birthtime = MAX2(pind.birthtime, part->path_start);
			dietime = MIN2(pind.dietime, part->path_end);
		}
		else {
			float tb = pind.birthtime;
			birthtime = tb + part->path_start * (pind.dietime - tb);
			dietime = tb + part->path_end * (pind.dietime - tb);
		}

		if (birthtime >= dietime) {
			cache[p]->steps = -1;
			continue;
		}

		dietime = birthtime + pa_length * (dietime - birthtime);

		/*--interpolate actual path from data points--*/
		for (k = 0, ca = cache[p]; k <= steps; k++, ca++) {
			time = (float)k / (float)steps;
			t = birthtime + time * (dietime - birthtime);
			result.time = -t;
			do_particle_interpolation(psys, p, pa, t, &pind, &result);
			copy_v3_v3(ca->co, result.co);

			/* dynamic hair is in object space */
			/* keyed and baked are already in global space */
			if (hair_dm)
				mul_m4_v3(sim->ob->obmat, ca->co);
			else if (!keyed && !baked && !(psys->flag & PSYS_GLOBAL_HAIR))
				mul_m4_v3(hairmat, ca->co);

			copy_v3_v3(ca->col, col);
		}
		
		/*--modify paths and calculate rotation & velocity--*/

		if (!(psys->flag & PSYS_GLOBAL_HAIR)) {
			/* apply effectors */
			if ((psys->part->flag & PART_CHILD_EFFECT) == 0) {
				float effector = 1.0f;
				if (vg_effector)
					effector *= psys_particle_value_from_verts(psmd->dm, psys->part->from, pa, vg_effector);

				sub_v3_v3v3(vec, (cache[p] + 1)->co, cache[p]->co);
				length = len_v3(vec);

				for (k = 1, ca = cache[p] + 1; k <= steps; k++, ca++)
					do_path_effectors(sim, p, ca, k, steps, cache[p]->co, effector, dfra, cfra, &length, vec);
			}

			/* apply guide curves to path data */
			if (sim->psys->effectors && (psys->part->flag & PART_CHILD_EFFECT) == 0) {
				for (k = 0, ca = cache[p]; k <= steps; k++, ca++)
					/* ca is safe to cast, since only co and vel are used */
					do_guides(sim->psys->effectors, (ParticleKey *)ca, p, (float)k / (float)steps);
			}

			/* lattices have to be calculated separately to avoid mixups between effector calculations */
			if (psys->lattice_deform_data) {
				for (k = 0, ca = cache[p]; k <= steps; k++, ca++)
					calc_latt_deform(psys->lattice_deform_data, ca->co, 1.0f);
			}
		}

		/* finally do rotation & velocity */
		for (k = 1, ca = cache[p] + 1; k <= steps; k++, ca++) {
			cache_key_incremental_rotation(ca, ca - 1, ca - 2, prev_tangent, k);

			if (k == steps)
				copy_qt_qt(ca->rot, (ca - 1)->rot);

			/* set velocity */
			sub_v3_v3v3(ca->vel, ca->co, (ca - 1)->co);

			if (k == 1)
				copy_v3_v3((ca - 1)->vel, ca->vel);

			ca->time = (float)k / (float)steps;
		}
		/* First rotation is based on emitting face orientation.
		 * This is way better than having flipping rotations resulting
		 * from using a global axis as a rotation pole (vec_to_quat()).
		 * It's not an ideal solution though since it disregards the
		 * initial tangent, but taking that in to account will allow
		 * the possibility of flipping again. -jahka
		 */
		mat3_to_quat_is_ok(cache[p]->rot, rotmat);
	}

	psys->totcached = totpart;

	if (psys->lattice_deform_data) {
		end_latt_deform(psys->lattice_deform_data);
		psys->lattice_deform_data = NULL;
	}

	if (vg_effector)
		MEM_freeN(vg_effector);

	if (vg_length)
		MEM_freeN(vg_length);
}
void psys_cache_edit_paths(Scene *scene, Object *ob, PTCacheEdit *edit, float cfra)
{
	ParticleCacheKey *ca, **cache = edit->pathcache;
	ParticleEditSettings *pset = &scene->toolsettings->particle;
	
	PTCacheEditPoint *point = NULL;
	PTCacheEditKey *ekey = NULL;

	ParticleSystem *psys = edit->psys;
	ParticleSystemModifierData *psmd = psys_get_modifier(ob, psys);
	ParticleData *pa = psys ? psys->particles : NULL;

	ParticleInterpolationData pind;
	ParticleKey result;
	
	float birthtime = 0.0f, dietime = 0.0f;
	float t, time = 0.0f, keytime = 0.0f /*, frs_sec */;
	float hairmat[4][4], rotmat[3][3], prev_tangent[3] = {0.0f, 0.0f, 0.0f};
	int k, i;
	int steps = (int)pow(2.0, (double)pset->draw_step);
	int totpart = edit->totpoint, recalc_set = 0;
	float sel_col[3];
	float nosel_col[3];

	steps = MAX2(steps, 4);

	if (!cache || edit->totpoint != edit->totcached) {
		/* clear out old and create new empty path cache */
		psys_free_path_cache(edit->psys, edit);
		cache = edit->pathcache = psys_alloc_path_cache_buffers(&edit->pathcachebufs, totpart, steps + 1);

		/* set flag for update (child particles check this too) */
		for (i = 0, point = edit->points; i < totpart; i++, point++)
			point->flag |= PEP_EDIT_RECALC;
		recalc_set = 1;
	}

	/* frs_sec = (psys || edit->pid.flag & PTCACHE_VEL_PER_SEC) ? 25.0f : 1.0f; */ /* UNUSED */

	if (pset->brushtype == PE_BRUSH_WEIGHT) {
		; /* use weight painting colors now... */
	}
	else {
		sel_col[0] = (float)edit->sel_col[0] / 255.0f;
		sel_col[1] = (float)edit->sel_col[1] / 255.0f;
		sel_col[2] = (float)edit->sel_col[2] / 255.0f;
		nosel_col[0] = (float)edit->nosel_col[0] / 255.0f;
		nosel_col[1] = (float)edit->nosel_col[1] / 255.0f;
		nosel_col[2] = (float)edit->nosel_col[2] / 255.0f;
	}

	/*---first main loop: create all actual particles' paths---*/
	for (i = 0, point = edit->points; i < totpart; i++, pa += pa ? 1 : 0, point++) {
		if (edit->totcached && !(point->flag & PEP_EDIT_RECALC))
			continue;

		if (point->totkey == 0)
			continue;

		ekey = point->keys;

		pind.keyed = 0;
		pind.cache = NULL;
		pind.epoint = point;
		pind.bspline = psys ? (psys->part->flag & PART_HAIR_BSPLINE) : 0;
		pind.dm = NULL;


		/* should init_particle_interpolation set this ? */
		if (pset->brushtype == PE_BRUSH_WEIGHT) {
			pind.hkey[0] = NULL;
			/* pa != NULL since the weight brush is only available for hair */
			pind.hkey[1] = pa->hair;
		}


		memset(cache[i], 0, sizeof(*cache[i]) * (steps + 1));

		cache[i]->steps = steps;

		/*--get the first data points--*/
		init_particle_interpolation(ob, psys, pa, &pind);

		if (psys) {
			psys_mat_hair_to_global(ob, psmd->dm, psys->part->from, pa, hairmat);
			copy_v3_v3(rotmat[0], hairmat[2]);
			copy_v3_v3(rotmat[1], hairmat[1]);
			copy_v3_v3(rotmat[2], hairmat[0]);
		}

		birthtime = pind.birthtime;
		dietime = pind.dietime;

		if (birthtime >= dietime) {
			cache[i]->steps = -1;
			continue;
		}

		/*--interpolate actual path from data points--*/
		for (k = 0, ca = cache[i]; k <= steps; k++, ca++) {
			time = (float)k / (float)steps;
			t = birthtime + time * (dietime - birthtime);
			result.time = -t;
			do_particle_interpolation(psys, i, pa, t, &pind, &result);
			copy_v3_v3(ca->co, result.co);

			/* non-hair points are already in global space */
			if (psys && !(psys->flag & PSYS_GLOBAL_HAIR)) {
				mul_m4_v3(hairmat, ca->co);

				if (k) {
					cache_key_incremental_rotation(ca, ca - 1, ca - 2, prev_tangent, k);

					if (k == steps)
						copy_qt_qt(ca->rot, (ca - 1)->rot);

					/* set velocity */
					sub_v3_v3v3(ca->vel, ca->co, (ca - 1)->co);

					if (k == 1)
						copy_v3_v3((ca - 1)->vel, ca->vel);
				}
			}
			else {
				ca->vel[0] = ca->vel[1] = 0.0f;
				ca->vel[2] = 1.0f;
			}

			/* selection coloring in edit mode */
			if (pset->brushtype == PE_BRUSH_WEIGHT) {
				float t2;

				if (k == 0) {
					weight_to_rgb(ca->col, pind.hkey[1]->weight);
				}
				else {
					float w1[3], w2[3];
					keytime = (t - (*pind.ekey[0]->time)) / ((*pind.ekey[1]->time) - (*pind.ekey[0]->time));

					weight_to_rgb(w1, pind.hkey[0]->weight);
					weight_to_rgb(w2, pind.hkey[1]->weight);

					interp_v3_v3v3(ca->col, w1, w2, keytime);
				}

				/* at the moment this is only used for weight painting.
				 * will need to move out of this check if its used elsewhere. */
				t2 = birthtime + ((float)k / (float)steps) * (dietime - birthtime);

				while (pind.hkey[1]->time < t2) pind.hkey[1]++;
				pind.hkey[0] = pind.hkey[1] - 1;
			}
			else {
				if ((ekey + (pind.ekey[0] - point->keys))->flag & PEK_SELECT) {
					if ((ekey + (pind.ekey[1] - point->keys))->flag & PEK_SELECT) {
						copy_v3_v3(ca->col, sel_col);
					}
					else {
						keytime = (t - (*pind.ekey[0]->time)) / ((*pind.ekey[1]->time) - (*pind.ekey[0]->time));
						interp_v3_v3v3(ca->col, sel_col, nosel_col, keytime);
					}
				}
				else {
					if ((ekey + (pind.ekey[1] - point->keys))->flag & PEK_SELECT) {
						keytime = (t - (*pind.ekey[0]->time)) / ((*pind.ekey[1]->time) - (*pind.ekey[0]->time));
						interp_v3_v3v3(ca->col, nosel_col, sel_col, keytime);
					}
					else {
						copy_v3_v3(ca->col, nosel_col);
					}
				}
			}

			ca->time = t;
		}
		if (psys && !(psys->flag & PSYS_GLOBAL_HAIR)) {
			/* First rotation is based on emitting face orientation.
			 * This is way better than having flipping rotations resulting
			 * from using a global axis as a rotation pole (vec_to_quat()).
			 * It's not an ideal solution though since it disregards the
			 * initial tangent, but taking that in to account will allow
			 * the possibility of flipping again. -jahka
			 */
			mat3_to_quat_is_ok(cache[i]->rot, rotmat);
		}
	}

	edit->totcached = totpart;

	if (psys) {
		ParticleSimulationData sim = {0};
		sim.scene = scene;
		sim.ob = ob;
		sim.psys = psys;
		sim.psmd = psys_get_modifier(ob, psys);

		psys_cache_child_paths(&sim, cfra, 1);
	}

	/* clear recalc flag if set here */
	if (recalc_set) {
		for (i = 0, point = edit->points; i < totpart; i++, point++)
			point->flag &= ~PEP_EDIT_RECALC;
	}
}
/************************************************/
/*			Particle Key handling				*/
/************************************************/
void copy_particle_key(ParticleKey *to, ParticleKey *from, int time)
{
	if (time) {
		memcpy(to, from, sizeof(ParticleKey));
	}
	else {
		float to_time = to->time;
		memcpy(to, from, sizeof(ParticleKey));
		to->time = to_time;
	}
}
void psys_get_from_key(ParticleKey *key, float loc[3], float vel[3], float rot[4], float *time)
{
	if (loc) copy_v3_v3(loc, key->co);
	if (vel) copy_v3_v3(vel, key->vel);
	if (rot) copy_qt_qt(rot, key->rot);
	if (time) *time = key->time;
}
/*-------changing particle keys from space to another-------*/
#if 0
static void key_from_object(Object *ob, ParticleKey *key)
{
	float q[4];

	add_v3_v3(key->vel, key->co);

	mul_m4_v3(ob->obmat, key->co);
	mul_m4_v3(ob->obmat, key->vel);
	mat4_to_quat(q, ob->obmat);

	sub_v3_v3v3(key->vel, key->vel, key->co);
	mul_qt_qtqt(key->rot, q, key->rot);
}
#endif

static void triatomat(float *v1, float *v2, float *v3, float (*uv)[2], float mat[4][4])
{
	float det, w1, w2, d1[2], d2[2];

	memset(mat, 0, sizeof(float) * 4 * 4);
	mat[3][3] = 1.0f;

	/* first axis is the normal */
	normal_tri_v3(mat[2], v1, v2, v3);

	/* second axis along (1, 0) in uv space */
	if (uv) {
		d1[0] = uv[1][0] - uv[0][0];
		d1[1] = uv[1][1] - uv[0][1];
		d2[0] = uv[2][0] - uv[0][0];
		d2[1] = uv[2][1] - uv[0][1];

		det = d2[0] * d1[1] - d2[1] * d1[0];

		if (det != 0.0f) {
			det = 1.0f / det;
			w1 = -d2[1] * det;
			w2 = d1[1] * det;

			mat[1][0] = w1 * (v2[0] - v1[0]) + w2 * (v3[0] - v1[0]);
			mat[1][1] = w1 * (v2[1] - v1[1]) + w2 * (v3[1] - v1[1]);
			mat[1][2] = w1 * (v2[2] - v1[2]) + w2 * (v3[2] - v1[2]);
			normalize_v3(mat[1]);
		}
		else
			mat[1][0] = mat[1][1] = mat[1][2] = 0.0f;
	}
	else {
		sub_v3_v3v3(mat[1], v2, v1);
		normalize_v3(mat[1]);
	}
	
	/* third as a cross product */
	cross_v3_v3v3(mat[0], mat[1], mat[2]);
}

static void psys_face_mat(Object *ob, DerivedMesh *dm, ParticleData *pa, float mat[4][4], int orco)
{
	float v[3][3];
	MFace *mface;
	OrigSpaceFace *osface;
	float (*orcodata)[3];

	int i = (ELEM(pa->num_dmcache, DMCACHE_ISCHILD, DMCACHE_NOTFOUND)) ? pa->num : pa->num_dmcache;
	if (i == -1 || i >= dm->getNumTessFaces(dm)) { unit_m4(mat); return; }

	mface = dm->getTessFaceData(dm, i, CD_MFACE);
	osface = dm->getTessFaceData(dm, i, CD_ORIGSPACE);
	
	if (orco && (orcodata = dm->getVertDataArray(dm, CD_ORCO))) {
		copy_v3_v3(v[0], orcodata[mface->v1]);
		copy_v3_v3(v[1], orcodata[mface->v2]);
		copy_v3_v3(v[2], orcodata[mface->v3]);

		/* ugly hack to use non-transformed orcos, since only those
		 * give symmetric results for mirroring in particle mode */
		if (DM_get_vert_data_layer(dm, CD_ORIGINDEX))
			BKE_mesh_orco_verts_transform(ob->data, v, 3, 1);
	}
	else {
		dm->getVertCo(dm, mface->v1, v[0]);
		dm->getVertCo(dm, mface->v2, v[1]);
		dm->getVertCo(dm, mface->v3, v[2]);
	}

	triatomat(v[0], v[1], v[2], (osface) ? osface->uv : NULL, mat);
}

void psys_mat_hair_to_object(Object *UNUSED(ob), DerivedMesh *dm, short from, ParticleData *pa, float hairmat[4][4])
{
	float vec[3];

	/* can happen when called from a different object's modifier */
	if (!dm) {
		unit_m4(hairmat);
		return;
	}
	
	psys_face_mat(0, dm, pa, hairmat, 0);
	psys_particle_on_dm(dm, from, pa->num, pa->num_dmcache, pa->fuv, pa->foffset, vec, 0, 0, 0, 0, 0);
	copy_v3_v3(hairmat[3], vec);
}

void psys_mat_hair_to_orco(Object *ob, DerivedMesh *dm, short from, ParticleData *pa, float hairmat[4][4])
{
	float vec[3], orco[3];

	psys_face_mat(ob, dm, pa, hairmat, 1);
	psys_particle_on_dm(dm, from, pa->num, pa->num_dmcache, pa->fuv, pa->foffset, vec, 0, 0, 0, orco, 0);

	/* see psys_face_mat for why this function is called */
	if (DM_get_vert_data_layer(dm, CD_ORIGINDEX))
		BKE_mesh_orco_verts_transform(ob->data, &orco, 1, 1);
	copy_v3_v3(hairmat[3], orco);
}

void psys_vec_rot_to_face(DerivedMesh *dm, ParticleData *pa, float vec[3])
{
	float mat[4][4];

	psys_face_mat(0, dm, pa, mat, 0);
	transpose_m4(mat); /* cheap inverse for rotation matrix */
	mul_mat3_m4_v3(mat, vec);
}

void psys_mat_hair_to_global(Object *ob, DerivedMesh *dm, short from, ParticleData *pa, float hairmat[4][4])
{
	float facemat[4][4];

	psys_mat_hair_to_object(ob, dm, from, pa, facemat);

	mul_m4_m4m4(hairmat, ob->obmat, facemat);
}

/************************************************/
/*			ParticleSettings handling			*/
/************************************************/
ModifierData *object_add_particle_system(Scene *scene, Object *ob, const char *name)
{
	ParticleSystem *psys;
	ModifierData *md;
	ParticleSystemModifierData *psmd;

	if (!ob || ob->type != OB_MESH)
		return NULL;

	psys = ob->particlesystem.first;
	for (; psys; psys = psys->next)
		psys->flag &= ~PSYS_CURRENT;

	psys = MEM_callocN(sizeof(ParticleSystem), "particle_system");
	psys->pointcache = BKE_ptcache_add(&psys->ptcaches);
	BLI_addtail(&ob->particlesystem, psys);

	psys->part = psys_new_settings(DATA_("ParticleSettings"), NULL);

	if (BLI_countlist(&ob->particlesystem) > 1)
		BLI_snprintf(psys->name, sizeof(psys->name), DATA_("ParticleSystem %i"), BLI_countlist(&ob->particlesystem));
	else
		BLI_strncpy(psys->name, DATA_("ParticleSystem"), sizeof(psys->name));

	md = modifier_new(eModifierType_ParticleSystem);

	if (name)
		BLI_strncpy_utf8(md->name, name, sizeof(md->name));
	else
		BLI_snprintf(md->name, sizeof(md->name), DATA_("ParticleSystem %i"), BLI_countlist(&ob->particlesystem));
	modifier_unique_name(&ob->modifiers, md);

	psmd = (ParticleSystemModifierData *) md;
	psmd->psys = psys;
	BLI_addtail(&ob->modifiers, md);

	psys->totpart = 0;
	psys->flag = PSYS_CURRENT;
	psys->cfra = BKE_scene_frame_get_from_ctime(scene, CFRA + 1);

	DAG_relations_tag_update(G.main);
	DAG_id_tag_update(&ob->id, OB_RECALC_DATA);

	return md;
}
void object_remove_particle_system(Scene *UNUSED(scene), Object *ob)
{
	ParticleSystem *psys = psys_get_current(ob);
	ParticleSystemModifierData *psmd;
	ModifierData *md;

	if (!psys)
		return;

	/* clear all other appearances of this pointer (like on smoke flow modifier) */
	if ((md = modifiers_findByType(ob, eModifierType_Smoke))) {
		SmokeModifierData *smd = (SmokeModifierData *)md;
		if ((smd->type == MOD_SMOKE_TYPE_FLOW) && smd->flow && smd->flow->psys)
			if (smd->flow->psys == psys)
				smd->flow->psys = NULL;
	}

	if ((md = modifiers_findByType(ob, eModifierType_DynamicPaint))) {
		DynamicPaintModifierData *pmd = (DynamicPaintModifierData *)md;
		if (pmd->brush && pmd->brush->psys)
			if (pmd->brush->psys == psys)
				pmd->brush->psys = NULL;
	}

	/* clear modifier */
	psmd = psys_get_modifier(ob, psys);
	BLI_remlink(&ob->modifiers, psmd);
	modifier_free((ModifierData *)psmd);

	/* clear particle system */
	BLI_remlink(&ob->particlesystem, psys);
	psys_free(ob, psys);

	if (ob->particlesystem.first)
		((ParticleSystem *) ob->particlesystem.first)->flag |= PSYS_CURRENT;
	else
		ob->mode &= ~OB_MODE_PARTICLE_EDIT;

	DAG_relations_tag_update(G.main);
	DAG_id_tag_update(&ob->id, OB_RECALC_DATA);
}
static void default_particle_settings(ParticleSettings *part)
{
	part->type = PART_EMITTER;
	part->distr = PART_DISTR_JIT;
	part->draw_as = PART_DRAW_REND;
	part->ren_as = PART_DRAW_HALO;
	part->bb_uv_split = 1;
	part->bb_align = PART_BB_VIEW;
	part->bb_split_offset = PART_BB_OFF_LINEAR;
	part->flag = PART_EDISTR | PART_TRAND | PART_HIDE_ADVANCED_HAIR;

	part->sta = 1.0;
	part->end = 200.0;
	part->lifetime = 50.0;
	part->jitfac = 1.0;
	part->totpart = 1000;
	part->grid_res = 10;
	part->timetweak = 1.0;
	part->courant_target = 0.2;
	
	part->integrator = PART_INT_MIDPOINT;
	part->phystype = PART_PHYS_NEWTON;
	part->hair_step = 5;
	part->keys_step = 5;
	part->draw_step = 2;
	part->ren_step = 3;
	part->adapt_angle = 5;
	part->adapt_pix = 3;
	part->kink_axis = 2;
	part->kink_amp_clump = 1.f;
	part->reactevent = PART_EVENT_DEATH;
	part->disp = 100;
	part->from = PART_FROM_FACE;

	part->normfac = 1.0f;

	part->mass = 1.0;
	part->size = 0.05;
	part->childsize = 1.0;

	part->rotmode = PART_ROT_VEL;
	part->avemode = PART_AVE_VELOCITY;

	part->child_nbr = 10;
	part->ren_child_nbr = 100;
	part->childrad = 0.2f;
	part->childflat = 0.0f;
	part->clumppow = 0.0f;
	part->kink_amp = 0.2f;
	part->kink_freq = 2.0;

	part->rough1_size = 1.0;
	part->rough2_size = 1.0;
	part->rough_end_shape = 1.0;

	part->clength = 1.0f;
	part->clength_thres = 0.0f;

	part->draw = PART_DRAW_EMITTER;
	part->draw_line[0] = 0.5;
	part->path_start = 0.0f;
	part->path_end = 1.0f;

	part->bb_size[0] = part->bb_size[1] = 1.0f;

	part->keyed_loops = 1;

	part->color_vec_max = 1.f;
	part->draw_col = PART_DRAW_COL_MAT;

	part->simplify_refsize = 1920;
	part->simplify_rate = 1.0f;
	part->simplify_transition = 0.1f;
	part->simplify_viewport = 0.8;

	if (!part->effector_weights)
		part->effector_weights = BKE_add_effector_weights(NULL);

	part->omat = 1;
	part->use_modifier_stack = false;
}


ParticleSettings *psys_new_settings(const char *name, Main *main)
{
	ParticleSettings *part;

	if (main == NULL)
		main = G.main;

	part = BKE_libblock_alloc(main, ID_PA, name);
	
	default_particle_settings(part);

	return part;
}

ParticleSettings *BKE_particlesettings_copy(ParticleSettings *part)
{
	ParticleSettings *partn;
	int a;

	partn = BKE_libblock_copy(&part->id);
	partn->pd = MEM_dupallocN(part->pd);
	partn->pd2 = MEM_dupallocN(part->pd2);
	partn->effector_weights = MEM_dupallocN(part->effector_weights);
	partn->fluid = MEM_dupallocN(part->fluid);

	partn->boids = boid_copy_settings(part->boids);

	for (a = 0; a < MAX_MTEX; a++) {
		if (part->mtex[a]) {
			partn->mtex[a] = MEM_mallocN(sizeof(MTex), "psys_copy_tex");
			memcpy(partn->mtex[a], part->mtex[a], sizeof(MTex));
			id_us_plus((ID *)partn->mtex[a]->tex);
		}
	}

	BLI_duplicatelist(&partn->dupliweights, &part->dupliweights);
	
	return partn;
}

static void expand_local_particlesettings(ParticleSettings *part)
{
	int i;
	id_lib_extern((ID *)part->dup_group);

	for (i = 0; i < MAX_MTEX; i++) {
		if (part->mtex[i]) id_lib_extern((ID *)part->mtex[i]->tex);
	}
}

void BKE_particlesettings_make_local(ParticleSettings *part)
{
	Main *bmain = G.main;
	Object *ob;
	bool is_local = false, is_lib = false;

	/* - only lib users: do nothing
	 * - only local users: set flag
	 * - mixed: make copy
	 */
	
	if (part->id.lib == 0) return;
	if (part->id.us == 1) {
		id_clear_lib_data(bmain, &part->id);
		expand_local_particlesettings(part);
		return;
	}

	/* test objects */
	for (ob = bmain->object.first; ob && ELEM(false, is_lib, is_local); ob = ob->id.next) {
		ParticleSystem *psys = ob->particlesystem.first;
		for (; psys; psys = psys->next) {
			if (psys->part == part) {
				if (ob->id.lib) is_lib = true;
				else is_local = true;
			}
		}
	}
	
	if (is_local && is_lib == false) {
		id_clear_lib_data(bmain, &part->id);
		expand_local_particlesettings(part);
	}
	else if (is_local && is_lib) {
		ParticleSettings *part_new = BKE_particlesettings_copy(part);
		part_new->id.us = 0;

		/* Remap paths of new ID using old library as base. */
		BKE_id_lib_local_paths(bmain, part->id.lib, &part_new->id);

		/* do objects */
		for (ob = bmain->object.first; ob; ob = ob->id.next) {
			ParticleSystem *psys;
			for (psys = ob->particlesystem.first; psys; psys = psys->next) {
				if (psys->part == part && ob->id.lib == 0) {
					psys->part = part_new;
					part_new->id.us++;
					part->id.us--;
				}
			}
		}
	}
}

/************************************************/
/*			Textures							*/
/************************************************/

static int get_particle_uv(DerivedMesh *dm, ParticleData *pa, int face_index, const float fuv[4], char *name, float *texco)
{
	MFace *mf;
	MTFace *tf;
	int i;
	
	tf = CustomData_get_layer_named(&dm->faceData, CD_MTFACE, name);

	if (tf == NULL)
		tf = CustomData_get_layer(&dm->faceData, CD_MTFACE);

	if (tf == NULL)
		return 0;

	if (pa) {
		i = ELEM(pa->num_dmcache, DMCACHE_NOTFOUND, DMCACHE_ISCHILD) ? pa->num : pa->num_dmcache;
		if (i >= dm->getNumTessFaces(dm))
			i = -1;
	}
	else
		i = face_index;

	if (i == -1) {
		texco[0] = 0.0f;
		texco[1] = 0.0f;
		texco[2] = 0.0f;
	}
	else {
		mf = dm->getTessFaceData(dm, i, CD_MFACE);

		psys_interpolate_uvs(&tf[i], mf->v4, fuv, texco);

		texco[0] = texco[0] * 2.0f - 1.0f;
		texco[1] = texco[1] * 2.0f - 1.0f;
		texco[2] = 0.0f;
	}

	return 1;
}

#define SET_PARTICLE_TEXTURE(type, pvalue, texfac)                            \
	if ((event & mtex->mapto) & type) {                                       \
		pvalue = texture_value_blend(def, pvalue, value, texfac, blend);      \
	} (void)0

#define CLAMP_PARTICLE_TEXTURE_POS(type, pvalue)                              \
	if (event & type) {                                                       \
		if (pvalue < 0.0f)                                                    \
			pvalue = 1.0f + pvalue;                                           \
		CLAMP(pvalue, 0.0f, 1.0f);                                            \
	} (void)0

#define CLAMP_PARTICLE_TEXTURE_POSNEG(type, pvalue)                           \
	if (event & type) {                                                       \
		CLAMP(pvalue, -1.0f, 1.0f);                                           \
	} (void)0

static void get_cpa_texture(DerivedMesh *dm, ParticleSystem *psys, ParticleSettings *part, ParticleData *par, int child_index, int face_index, const float fw[4], float *orco, ParticleTexture *ptex, int event, float cfra)
{
	MTex *mtex, **mtexp = part->mtex;
	int m;
	float value, rgba[4], texvec[3];

	ptex->ivel = ptex->life = ptex->exist = ptex->size = ptex->damp =
	ptex->gravity = ptex->field = ptex->time = ptex->clump = ptex->kink =
	ptex->effector = ptex->rough1 = ptex->rough2 = ptex->roughe = 1.0f;

	ptex->length = 1.0f - part->randlength * psys_frand(psys, child_index + 26);
	ptex->length *= part->clength_thres < psys_frand(psys, child_index + 27) ? part->clength : 1.0f;

	for (m = 0; m < MAX_MTEX; m++, mtexp++) {
		mtex = *mtexp;
		if (mtex && mtex->tex && mtex->mapto) {
			float def = mtex->def_var;
			short blend = mtex->blendtype;
			short texco = mtex->texco;

			if (ELEM(texco, TEXCO_UV, TEXCO_ORCO) && (ELEM(part->from, PART_FROM_FACE, PART_FROM_VOLUME) == 0 || part->distr == PART_DISTR_GRID))
				texco = TEXCO_GLOB;

			switch (texco) {
				case TEXCO_GLOB:
					copy_v3_v3(texvec, par->state.co);
					break;
				case TEXCO_OBJECT:
					copy_v3_v3(texvec, par->state.co);
					if (mtex->object)
						mul_m4_v3(mtex->object->imat, texvec);
					break;
				case TEXCO_UV:
					if (fw && get_particle_uv(dm, NULL, face_index, fw, mtex->uvname, texvec))
						break;
				/* no break, failed to get uv's, so let's try orco's */
				case TEXCO_ORCO:
					copy_v3_v3(texvec, orco);
					break;
				case TEXCO_PARTICLE:
					/* texture coordinates in range [-1, 1] */
					texvec[0] = 2.f * (cfra - par->time) / (par->dietime - par->time) - 1.f;
					texvec[1] = 0.f;
					texvec[2] = 0.f;
					break;
			}

			externtex(mtex, texvec, &value, rgba, rgba + 1, rgba + 2, rgba + 3, 0, NULL);

			if ((event & mtex->mapto) & PAMAP_ROUGH)
				ptex->rough1 = ptex->rough2 = ptex->roughe = texture_value_blend(def, ptex->rough1, value, mtex->roughfac, blend);

			SET_PARTICLE_TEXTURE(PAMAP_LENGTH, ptex->length, mtex->lengthfac);
			SET_PARTICLE_TEXTURE(PAMAP_CLUMP, ptex->clump, mtex->clumpfac);
			SET_PARTICLE_TEXTURE(PAMAP_KINK, ptex->kink, mtex->kinkfac);
			SET_PARTICLE_TEXTURE(PAMAP_DENS, ptex->exist, mtex->padensfac);
		}
	}

	CLAMP_PARTICLE_TEXTURE_POS(PAMAP_LENGTH, ptex->length);
	CLAMP_PARTICLE_TEXTURE_POS(PAMAP_CLUMP, ptex->clump);
	CLAMP_PARTICLE_TEXTURE_POS(PAMAP_KINK, ptex->kink);
	CLAMP_PARTICLE_TEXTURE_POS(PAMAP_ROUGH, ptex->rough1);
	CLAMP_PARTICLE_TEXTURE_POS(PAMAP_DENS, ptex->exist);
}
void psys_get_texture(ParticleSimulationData *sim, ParticleData *pa, ParticleTexture *ptex, int event, float cfra)
{
	Object *ob = sim->ob;
	Mesh *me = (Mesh *)ob->data;
	ParticleSettings *part = sim->psys->part;
	MTex **mtexp = part->mtex;
	MTex *mtex;
	int m;
	float value, rgba[4], co[3], texvec[3];
	int setvars = 0;

	/* initialize ptex */
	ptex->ivel = ptex->life = ptex->exist = ptex->size = ptex->damp =
	ptex->gravity = ptex->field = ptex->length = ptex->clump = ptex->kink =
	ptex->effector = ptex->rough1 = ptex->rough2 = ptex->roughe = 1.0f;

	ptex->time = (float)(pa - sim->psys->particles) / (float)sim->psys->totpart;

	for (m = 0; m < MAX_MTEX; m++, mtexp++) {
		mtex = *mtexp;
		if (mtex && mtex->tex && mtex->mapto) {
			float def = mtex->def_var;
			short blend = mtex->blendtype;
			short texco = mtex->texco;

			if (texco == TEXCO_UV && (ELEM(part->from, PART_FROM_FACE, PART_FROM_VOLUME) == 0 || part->distr == PART_DISTR_GRID))
				texco = TEXCO_GLOB;

			switch (texco) {
				case TEXCO_GLOB:
					copy_v3_v3(texvec, pa->state.co);
					break;
				case TEXCO_OBJECT:
					copy_v3_v3(texvec, pa->state.co);
					if (mtex->object)
						mul_m4_v3(mtex->object->imat, texvec);
					break;
				case TEXCO_UV:
					if (get_particle_uv(sim->psmd->dm, pa, 0, pa->fuv, mtex->uvname, texvec))
						break;
				/* no break, failed to get uv's, so let's try orco's */
				case TEXCO_ORCO:
					psys_particle_on_emitter(sim->psmd, sim->psys->part->from, pa->num, pa->num_dmcache, pa->fuv, pa->foffset, co, 0, 0, 0, texvec, 0);
					
					if (me->bb == NULL || (me->bb->flag & BOUNDBOX_DIRTY)) {
						BKE_mesh_texspace_calc(me);
					}
					sub_v3_v3(texvec, me->loc);
					if (me->size[0] != 0.0f) texvec[0] /= me->size[0];
					if (me->size[1] != 0.0f) texvec[1] /= me->size[1];
					if (me->size[2] != 0.0f) texvec[2] /= me->size[2];
					break;
				case TEXCO_PARTICLE:
					/* texture coordinates in range [-1, 1] */
					texvec[0] = 2.f * (cfra - pa->time) / (pa->dietime - pa->time) - 1.f;
					if (sim->psys->totpart > 0)
						texvec[1] = 2.f * (float)(pa - sim->psys->particles) / (float)sim->psys->totpart - 1.f;
					else
						texvec[1] = 0.0f;
					texvec[2] = 0.f;
					break;
			}

			externtex(mtex, texvec, &value, rgba, rgba + 1, rgba + 2, rgba + 3, 0, NULL);

			if ((event & mtex->mapto) & PAMAP_TIME) {
				/* the first time has to set the base value for time regardless of blend mode */
				if ((setvars & MAP_PA_TIME) == 0) {
					int flip = (mtex->timefac < 0.0f);
					float timefac = fabsf(mtex->timefac);
					ptex->time *= 1.0f - timefac;
					ptex->time += timefac * ((flip) ? 1.0f - value : value);
					setvars |= MAP_PA_TIME;
				}
				else
					ptex->time = texture_value_blend(def, ptex->time, value, mtex->timefac, blend);
			}
			SET_PARTICLE_TEXTURE(PAMAP_LIFE, ptex->life, mtex->lifefac);
			SET_PARTICLE_TEXTURE(PAMAP_DENS, ptex->exist, mtex->padensfac);
			SET_PARTICLE_TEXTURE(PAMAP_SIZE, ptex->size, mtex->sizefac);
			SET_PARTICLE_TEXTURE(PAMAP_IVEL, ptex->ivel, mtex->ivelfac);
			SET_PARTICLE_TEXTURE(PAMAP_FIELD, ptex->field, mtex->fieldfac);
			SET_PARTICLE_TEXTURE(PAMAP_GRAVITY, ptex->gravity, mtex->gravityfac);
			SET_PARTICLE_TEXTURE(PAMAP_DAMP, ptex->damp, mtex->dampfac);
			SET_PARTICLE_TEXTURE(PAMAP_LENGTH, ptex->length, mtex->lengthfac);
		}
	}

	CLAMP_PARTICLE_TEXTURE_POS(PAMAP_TIME, ptex->time);
	CLAMP_PARTICLE_TEXTURE_POS(PAMAP_LIFE, ptex->life);
	CLAMP_PARTICLE_TEXTURE_POS(PAMAP_DENS, ptex->exist);
	CLAMP_PARTICLE_TEXTURE_POS(PAMAP_SIZE, ptex->size);
	CLAMP_PARTICLE_TEXTURE_POSNEG(PAMAP_IVEL, ptex->ivel);
	CLAMP_PARTICLE_TEXTURE_POSNEG(PAMAP_FIELD, ptex->field);
	CLAMP_PARTICLE_TEXTURE_POSNEG(PAMAP_GRAVITY, ptex->gravity);
	CLAMP_PARTICLE_TEXTURE_POS(PAMAP_DAMP, ptex->damp);
	CLAMP_PARTICLE_TEXTURE_POS(PAMAP_LENGTH, ptex->length);
}
/************************************************/
/*			Particle State						*/
/************************************************/
float psys_get_timestep(ParticleSimulationData *sim)
{
	return 0.04f * sim->psys->part->timetweak;
}
float psys_get_child_time(ParticleSystem *psys, ChildParticle *cpa, float cfra, float *birthtime, float *dietime)
{
	ParticleSettings *part = psys->part;
	float time, life;

	if (part->childtype == PART_CHILD_FACES) {
		int w = 0;
		time = 0.0;
		while (w < 4 && cpa->pa[w] >= 0) {
			time += cpa->w[w] * (psys->particles + cpa->pa[w])->time;
			w++;
		}

		life = part->lifetime * (1.0f - part->randlife * psys_frand(psys, cpa - psys->child + 25));
	}
	else {
		ParticleData *pa = psys->particles + cpa->parent;

		time = pa->time;
		life = pa->lifetime;
	}

	if (birthtime)
		*birthtime = time;
	if (dietime)
		*dietime = time + life;

	return (cfra - time) / life;
}
float psys_get_child_size(ParticleSystem *psys, ChildParticle *cpa, float UNUSED(cfra), float *UNUSED(pa_time))
{
	ParticleSettings *part = psys->part;
	float size; // time XXX
	
	if (part->childtype == PART_CHILD_FACES)
		size = part->size;
	else
		size = psys->particles[cpa->parent].size;

	size *= part->childsize;

	if (part->childrandsize != 0.0f)
		size *= 1.0f - part->childrandsize * psys_frand(psys, cpa - psys->child + 26);

	return size;
}
static void get_child_modifier_parameters(ParticleSettings *part, ParticleThreadContext *ctx, ChildParticle *cpa, short cpa_from, int cpa_num, float *cpa_fuv, float *orco, ParticleTexture *ptex)
{
	ParticleSystem *psys = ctx->sim.psys;
	int i = cpa - psys->child;

	get_cpa_texture(ctx->dm, psys, part, psys->particles + cpa->pa[0], i, cpa_num, cpa_fuv, orco, ptex, PAMAP_DENS | PAMAP_CHILD, psys->cfra);


	if (ptex->exist < psys_frand(psys, i + 24))
		return;

	if (ctx->vg_length)
		ptex->length *= psys_interpolate_value_from_verts(ctx->dm, cpa_from, cpa_num, cpa_fuv, ctx->vg_length);
	if (ctx->vg_clump)
		ptex->clump *= psys_interpolate_value_from_verts(ctx->dm, cpa_from, cpa_num, cpa_fuv, ctx->vg_clump);
	if (ctx->vg_kink)
		ptex->kink *= psys_interpolate_value_from_verts(ctx->dm, cpa_from, cpa_num, cpa_fuv, ctx->vg_kink);
	if (ctx->vg_rough1)
		ptex->rough1 *= psys_interpolate_value_from_verts(ctx->dm, cpa_from, cpa_num, cpa_fuv, ctx->vg_rough1);
	if (ctx->vg_rough2)
		ptex->rough2 *= psys_interpolate_value_from_verts(ctx->dm, cpa_from, cpa_num, cpa_fuv, ctx->vg_rough2);
	if (ctx->vg_roughe)
		ptex->roughe *= psys_interpolate_value_from_verts(ctx->dm, cpa_from, cpa_num, cpa_fuv, ctx->vg_roughe);
	if (ctx->vg_effector)
		ptex->effector *= psys_interpolate_value_from_verts(ctx->dm, cpa_from, cpa_num, cpa_fuv, ctx->vg_effector);
}
static void do_child_modifiers(ParticleSimulationData *sim, ParticleTexture *ptex, ParticleKey *par, float *par_rot, ChildParticle *cpa, float *orco, float mat[4][4], ParticleKey *state, float t)
{
	ParticleSettings *part = sim->psys->part;
	int i = cpa - sim->psys->child;
	int guided = 0;

	float kink_freq = part->kink_freq;
	float rough1 = part->rough1;
	float rough2 = part->rough2;
	float rough_end = part->rough_end;

	if (ptex) {
		kink_freq *= ptex->kink;
		rough1 *= ptex->rough1;
		rough2 *= ptex->rough2;
		rough_end *= ptex->roughe;
	}

	if (part->flag & PART_CHILD_EFFECT)
		/* state is safe to cast, since only co and vel are used */
		guided = do_guides(sim->psys->effectors, (ParticleKey *)state, cpa->parent, t);

	if (guided == 0) {
		float clump = do_clump(state, par, t, part->clumpfac, part->clumppow, ptex ? ptex->clump : 1.f);

		if (kink_freq != 0.f) {
			float kink_amp = part->kink_amp * (1.f - part->kink_amp_clump * clump);

			do_kink(state, par, par_rot, t, kink_freq, part->kink_shape,
			        kink_amp, part->kink_flat, part->kink, part->kink_axis,
			        sim->ob->obmat, sim->psys->part->childtype == PART_CHILD_FACES);
		}
	}

	if (rough1 > 0.f)
		do_rough(orco, mat, t, rough1, part->rough1_size, 0.0, state);

	if (rough2 > 0.f) {
		float vec[3];
		psys_frand_vec(sim->psys, i + 27, vec);
		do_rough(vec, mat, t, rough2, part->rough2_size, part->rough2_thres, state);
	}

	if (rough_end > 0.f) {
		float vec[3];
		psys_frand_vec(sim->psys, i + 27, vec);
		do_rough_end(vec, mat, t, rough_end, part->rough_end_shape, state);
	}
}
/* get's hair (or keyed) particles state at the "path time" specified in state->time */
void psys_get_particle_on_path(ParticleSimulationData *sim, int p, ParticleKey *state, const bool vel)
{
	PARTICLE_PSMD;
	ParticleSystem *psys = sim->psys;
	ParticleSettings *part = sim->psys->part;
	Material *ma = give_current_material(sim->ob, part->omat);
	ParticleData *pa;
	ChildParticle *cpa;
	ParticleTexture ptex;
	ParticleKey *par = 0, keys[4], tstate;
	ParticleThreadContext ctx; /* fake thread context for child modifiers */
	ParticleInterpolationData pind;

	float t;
	float co[3], orco[3];
	float hairmat[4][4];
	int totpart = psys->totpart;
	int totchild = psys->totchild;
	short between = 0, edit = 0;

	int keyed = part->phystype & PART_PHYS_KEYED && psys->flag & PSYS_KEYED;
	int cached = !keyed && part->type != PART_HAIR;

	float *cpa_fuv; int cpa_num; short cpa_from;

	/* initialize keys to zero */
	memset(keys, 0, 4 * sizeof(ParticleKey));

	t = state->time;
	CLAMP(t, 0.0f, 1.0f);

	if (p < totpart) {
		/* interpolate pathcache directly if it exist */
		if (psys->pathcache) {
			ParticleCacheKey result;
			interpolate_pathcache(psys->pathcache[p], t, &result);
			copy_v3_v3(state->co, result.co);
			copy_v3_v3(state->vel, result.vel);
			copy_qt_qt(state->rot, result.rot);
		}
		/* otherwise interpolate with other means */
		else {
			pa = psys->particles + p;

			pind.keyed = keyed;
			pind.cache = cached ? psys->pointcache : NULL;
			pind.epoint = NULL;
			pind.bspline = (psys->part->flag & PART_HAIR_BSPLINE);
			/* pind.dm disabled in editmode means we don't get effectors taken into
			 * account when subdividing for instance */
			pind.dm = psys_in_edit_mode(sim->scene, psys) ? NULL : psys->hair_out_dm;
			init_particle_interpolation(sim->ob, psys, pa, &pind);
			do_particle_interpolation(psys, p, pa, t, &pind, state);

			if (pind.dm) {
				mul_m4_v3(sim->ob->obmat, state->co);
				mul_mat3_m4_v3(sim->ob->obmat, state->vel);
			}
			else if (!keyed && !cached && !(psys->flag & PSYS_GLOBAL_HAIR)) {
				if ((pa->flag & PARS_REKEY) == 0) {
					psys_mat_hair_to_global(sim->ob, sim->psmd->dm, part->from, pa, hairmat);
					mul_m4_v3(hairmat, state->co);
					mul_mat3_m4_v3(hairmat, state->vel);

					if (sim->psys->effectors && (part->flag & PART_CHILD_GUIDE) == 0) {
						do_guides(sim->psys->effectors, state, p, state->time);
						/* TODO: proper velocity handling */
					}

					if (psys->lattice_deform_data && edit == 0)
						calc_latt_deform(psys->lattice_deform_data, state->co, 1.0f);
				}
			}
		}
	}
	else if (totchild) {
		//invert_m4_m4(imat, ob->obmat);

		/* interpolate childcache directly if it exists */
		if (psys->childcache) {
			ParticleCacheKey result;
			interpolate_pathcache(psys->childcache[p - totpart], t, &result);
			copy_v3_v3(state->co, result.co);
			copy_v3_v3(state->vel, result.vel);
			copy_qt_qt(state->rot, result.rot);
		}
		else {
			cpa = psys->child + p - totpart;

			if (state->time < 0.0f)
				t = psys_get_child_time(psys, cpa, -state->time, NULL, NULL);

			if (totchild && part->childtype == PART_CHILD_FACES) {
				/* part->parents could still be 0 so we can't test with totparent */
				between = 1;
			}
			if (between) {
				int w = 0;
				float foffset;

				/* get parent states */
				while (w < 4 && cpa->pa[w] >= 0) {
					keys[w].time = state->time;
					psys_get_particle_on_path(sim, cpa->pa[w], keys + w, 1);
					w++;
				}

				/* get the original coordinates (orco) for texture usage */
				cpa_num = cpa->num;

				foffset = cpa->foffset;
				cpa_fuv = cpa->fuv;
				cpa_from = PART_FROM_FACE;

				psys_particle_on_emitter(psmd, cpa_from, cpa_num, DMCACHE_ISCHILD, cpa->fuv, foffset, co, 0, 0, 0, orco, 0);

				/* we need to save the actual root position of the child for positioning it accurately to the surface of the emitter */
				//copy_v3_v3(cpa_1st, co);

				//mul_m4_v3(ob->obmat, cpa_1st);

				pa = psys->particles + cpa->parent;

				if (part->type == PART_HAIR)
					psys_mat_hair_to_global(sim->ob, sim->psmd->dm, psys->part->from, pa, hairmat);
				else
					unit_m4(hairmat);

				pa = 0;
			}
			else {
				/* get the parent state */
				keys->time = state->time;
				psys_get_particle_on_path(sim, cpa->parent, keys, 1);

				/* get the original coordinates (orco) for texture usage */
				pa = psys->particles + cpa->parent;

				cpa_from = part->from;
				cpa_num = pa->num;
				cpa_fuv = pa->fuv;



				if (part->type == PART_HAIR) {
					psys_particle_on_emitter(psmd, cpa_from, cpa_num, DMCACHE_ISCHILD, cpa_fuv, pa->foffset, co, 0, 0, 0, orco, 0);
					psys_mat_hair_to_global(sim->ob, sim->psmd->dm, psys->part->from, pa, hairmat);
				}
				else {
					copy_v3_v3(orco, cpa->fuv);
					unit_m4(hairmat);
				}
			}

			/* correct child ipo timing */
#if 0 // XXX old animation system
			if ((part->flag & PART_ABS_TIME) == 0 && part->ipo) {
				calc_ipo(part->ipo, 100.0f * t);
				execute_ipo((ID *)part, part->ipo);
			}
#endif // XXX old animation system

			/* get different child parameters from textures & vgroups */
			memset(&ctx, 0, sizeof(ParticleThreadContext));
			ctx.sim = *sim;
			ctx.dm = psmd->dm;
			ctx.ma = ma;
			/* TODO: assign vertex groups */
			get_child_modifier_parameters(part, &ctx, cpa, cpa_from, cpa_num, cpa_fuv, orco, &ptex);

			if (between) {
				int w = 0;

				state->co[0] = state->co[1] = state->co[2] = 0.0f;
				state->vel[0] = state->vel[1] = state->vel[2] = 0.0f;

				/* child position is the weighted sum of parent positions */
				while (w < 4 && cpa->pa[w] >= 0) {
					state->co[0] += cpa->w[w] * keys[w].co[0];
					state->co[1] += cpa->w[w] * keys[w].co[1];
					state->co[2] += cpa->w[w] * keys[w].co[2];

					state->vel[0] += cpa->w[w] * keys[w].vel[0];
					state->vel[1] += cpa->w[w] * keys[w].vel[1];
					state->vel[2] += cpa->w[w] * keys[w].vel[2];
					w++;
				}
				/* apply offset for correct positioning */
				//add_v3_v3(state->co, cpa_1st);
			}
			else {
				/* offset the child from the parent position */
				offset_child(cpa, keys, keys->rot, state, part->childflat, part->childrad);
			}

			par = keys;

			if (vel)
				copy_particle_key(&tstate, state, 1);

			/* apply different deformations to the child path */
			do_child_modifiers(sim, &ptex, par, par->rot, cpa, orco, hairmat, state, t);

			/* try to estimate correct velocity */
			if (vel) {
				ParticleKey tstate;
				float length = len_v3(state->vel);

				if (t >= 0.001f) {
					tstate.time = t - 0.001f;
					psys_get_particle_on_path(sim, p, &tstate, 0);
					sub_v3_v3v3(state->vel, state->co, tstate.co);
					normalize_v3(state->vel);
				}
				else {
					tstate.time = t + 0.001f;
					psys_get_particle_on_path(sim, p, &tstate, 0);
					sub_v3_v3v3(state->vel, tstate.co, state->co);
					normalize_v3(state->vel);
				}

				mul_v3_fl(state->vel, length);
			}
		}
	}
}
/* gets particle's state at a time, returns 1 if particle exists and can be seen and 0 if not */
int psys_get_particle_state(ParticleSimulationData *sim, int p, ParticleKey *state, int always)
{
	ParticleSystem *psys = sim->psys;
	ParticleSettings *part = psys->part;
	ParticleData *pa = NULL;
	ChildParticle *cpa = NULL;
	float cfra;
	int totpart = psys->totpart;
	float timestep = psys_get_timestep(sim);

	/* negative time means "use current time" */
	cfra = state->time > 0 ? state->time : BKE_scene_frame_get(sim->scene);

	if (p >= totpart) {
		if (!psys->totchild)
			return 0;

		if (part->childtype == PART_CHILD_FACES) {
			if (!(psys->flag & PSYS_KEYED))
				return 0;

			cpa = psys->child + p - totpart;

			state->time = psys_get_child_time(psys, cpa, cfra, NULL, NULL);

			if (!always) {
				if ((state->time < 0.0f && !(part->flag & PART_UNBORN)) ||
				    (state->time > 1.0f && !(part->flag & PART_DIED)))
				{
					return 0;
				}
			}

			state->time = (cfra - (part->sta + (part->end - part->sta) * psys_frand(psys, p + 23))) / (part->lifetime * psys_frand(psys, p + 24));

			psys_get_particle_on_path(sim, p, state, 1);
			return 1;
		}
		else {
			cpa = sim->psys->child + p - totpart;
			pa = sim->psys->particles + cpa->parent;
		}
	}
	else {
		pa = sim->psys->particles + p;
	}

	if (pa) {
		if (!always) {
			if ((cfra < pa->time    && (part->flag & PART_UNBORN) == 0) ||
			    (cfra >= pa->dietime && (part->flag & PART_DIED)  == 0))
			{
				return 0;
			}
		}

		cfra = MIN2(cfra, pa->dietime);
	}

	if (sim->psys->flag & PSYS_KEYED) {
		state->time = -cfra;
		psys_get_particle_on_path(sim, p, state, 1);
		return 1;
	}
	else {
		if (cpa) {
			float mat[4][4];
			ParticleKey *key1;
			float t = (cfra - pa->time) / pa->lifetime;

			key1 = &pa->state;
			offset_child(cpa, key1, key1->rot, state, part->childflat, part->childrad);

			CLAMP(t, 0.0f, 1.0f);

			unit_m4(mat);
			do_child_modifiers(sim, NULL, key1, key1->rot, cpa, cpa->fuv, mat, state, t);

			if (psys->lattice_deform_data)
				calc_latt_deform(psys->lattice_deform_data, state->co, 1.0f);
		}
		else {
			if (pa->state.time == cfra || ELEM(part->phystype, PART_PHYS_NO, PART_PHYS_KEYED))
				copy_particle_key(state, &pa->state, 1);
			else if (pa->prev_state.time == cfra)
				copy_particle_key(state, &pa->prev_state, 1);
			else {
				float dfra, frs_sec = sim->scene->r.frs_sec;
				/* let's interpolate to try to be as accurate as possible */
				if (pa->state.time + 2.f >= state->time && pa->prev_state.time - 2.f <= state->time) {
					if (pa->prev_state.time >= pa->state.time || pa->prev_state.time < 0.f) {
						/* prev_state is wrong so let's not use it, this can happen at frames 1, 0 or particle birth */
						dfra = state->time - pa->state.time;

						copy_particle_key(state, &pa->state, 1);

						madd_v3_v3v3fl(state->co, state->co, state->vel, dfra / frs_sec);
					}
					else {
						ParticleKey keys[4];
						float keytime;

						copy_particle_key(keys + 1, &pa->prev_state, 1);
						copy_particle_key(keys + 2, &pa->state, 1);

						dfra = keys[2].time - keys[1].time;

						keytime = (state->time - keys[1].time) / dfra;

						/* convert velocity to timestep size */
						mul_v3_fl(keys[1].vel, dfra * timestep);
						mul_v3_fl(keys[2].vel, dfra * timestep);
						
						psys_interpolate_particle(-1, keys, keytime, state, 1);
						
						/* convert back to real velocity */
						mul_v3_fl(state->vel, 1.f / (dfra * timestep));

						interp_v3_v3v3(state->ave, keys[1].ave, keys[2].ave, keytime);
						interp_qt_qtqt(state->rot, keys[1].rot, keys[2].rot, keytime);
					}
				}
				else if (pa->state.time + 1.f >= state->time && pa->state.time - 1.f <= state->time) {
					/* linear interpolation using only pa->state */

					dfra = state->time - pa->state.time;

					copy_particle_key(state, &pa->state, 1);

					madd_v3_v3v3fl(state->co, state->co, state->vel, dfra / frs_sec);
				}
				else {
					/* extrapolating over big ranges is not accurate so let's just give something close to reasonable back */
					copy_particle_key(state, &pa->state, 0);
				}
			}

			if (sim->psys->lattice_deform_data)
				calc_latt_deform(sim->psys->lattice_deform_data, state->co, 1.0f);
		}
		
		return 1;
	}
}

void psys_get_dupli_texture(ParticleSystem *psys, ParticleSettings *part,
                            ParticleSystemModifierData *psmd, ParticleData *pa, ChildParticle *cpa,
                            float uv[2], float orco[3])
{
	MFace *mface;
	MTFace *mtface;
	float loc[3];
	int num;

	uv[0] = uv[1] = 0.f;

	if (cpa) {
		if (part->childtype == PART_CHILD_FACES) {
			mtface = CustomData_get_layer(&psmd->dm->faceData, CD_MTFACE);
			if (mtface) {
				mface = psmd->dm->getTessFaceData(psmd->dm, cpa->num, CD_MFACE);
				mtface += cpa->num;
				psys_interpolate_uvs(mtface, mface->v4, cpa->fuv, uv);
			}
		
			psys_particle_on_emitter(psmd, PART_FROM_FACE, cpa->num, DMCACHE_ISCHILD, cpa->fuv, cpa->foffset, loc, 0, 0, 0, orco, 0);
			return;
		}
		else {
			pa = psys->particles + cpa->pa[0];
		}
	}

	if (part->from == PART_FROM_FACE) {
		mtface = CustomData_get_layer(&psmd->dm->faceData, CD_MTFACE);
		num = pa->num_dmcache;

		if (num == DMCACHE_NOTFOUND)
			num = pa->num;

		if (num >= psmd->dm->getNumTessFaces(psmd->dm)) {
			/* happens when simplify is enabled
			 * gives invalid coords but would crash otherwise */
			num = DMCACHE_NOTFOUND;
		}

		if (mtface && !ELEM(num, DMCACHE_NOTFOUND, DMCACHE_ISCHILD)) {
			mface = psmd->dm->getTessFaceData(psmd->dm, num, CD_MFACE);
			mtface += num;
			psys_interpolate_uvs(mtface, mface->v4, pa->fuv, uv);
		}
	}

	psys_particle_on_emitter(psmd, part->from, pa->num, pa->num_dmcache, pa->fuv, pa->foffset, loc, 0, 0, 0, orco, 0);
}

void psys_get_dupli_path_transform(ParticleSimulationData *sim, ParticleData *pa, ChildParticle *cpa, ParticleCacheKey *cache, float mat[4][4], float *scale)
{
	Object *ob = sim->ob;
	ParticleSystem *psys = sim->psys;
	ParticleSystemModifierData *psmd = sim->psmd;
	float loc[3], nor[3], vec[3], side[3], len;
	float xvec[3] = {-1.0, 0.0, 0.0}, nmat[3][3];

	sub_v3_v3v3(vec, (cache + cache->steps)->co, cache->co);
	len = normalize_v3(vec);

	if (pa == NULL && psys->part->childflat != PART_CHILD_FACES)
		pa = psys->particles + cpa->pa[0];

	if (pa)
		psys_particle_on_emitter(psmd, sim->psys->part->from, pa->num, pa->num_dmcache, pa->fuv, pa->foffset, loc, nor, 0, 0, 0, 0);
	else
		psys_particle_on_emitter(psmd, PART_FROM_FACE, cpa->num, DMCACHE_ISCHILD, cpa->fuv, cpa->foffset, loc, nor, 0, 0, 0, 0);

	if (psys->part->rotmode == PART_ROT_VEL) {
		transpose_m3_m4(nmat, ob->imat);
		mul_m3_v3(nmat, nor);
		normalize_v3(nor);

		/* make sure that we get a proper side vector */
		if (fabsf(dot_v3v3(nor, vec)) > 0.999999) {
			if (fabsf(dot_v3v3(nor, xvec)) > 0.999999) {
				nor[0] = 0.0f;
				nor[1] = 1.0f;
				nor[2] = 0.0f;
			}
			else {
				nor[0] = 1.0f;
				nor[1] = 0.0f;
				nor[2] = 0.0f;
			}
		}
		cross_v3_v3v3(side, nor, vec);
		normalize_v3(side);

		/* rotate side vector around vec */
		if (psys->part->phasefac != 0) {
			float q_phase[4];
			float phasefac = psys->part->phasefac;
			if (psys->part->randphasefac != 0.0f)
				phasefac += psys->part->randphasefac * psys_frand(psys, (pa - psys->particles) + 20);
			axis_angle_to_quat(q_phase, vec, phasefac * (float)M_PI);

			mul_qt_v3(q_phase, side);
		}

		cross_v3_v3v3(nor, vec, side);

		unit_m4(mat);
		copy_v3_v3(mat[0], vec);
		copy_v3_v3(mat[1], side);
		copy_v3_v3(mat[2], nor);
	}
	else {
		quat_to_mat4(mat, pa->state.rot);
	}

	*scale = len;
}

void psys_make_billboard(ParticleBillboardData *bb, float xvec[3], float yvec[3], float zvec[3], float center[3])
{
	float onevec[3] = {0.0f, 0.0f, 0.0f}, tvec[3], tvec2[3];

	xvec[0] = 1.0f; xvec[1] = 0.0f; xvec[2] = 0.0f;
	yvec[0] = 0.0f; yvec[1] = 1.0f; yvec[2] = 0.0f;

	/* can happen with bad pointcache or physics calculation
	 * since this becomes geometry, nan's and inf's crash raytrace code.
	 * better not allow this. */
	if ((!finite(bb->vec[0])) || (!finite(bb->vec[1])) || (!finite(bb->vec[2])) ||
	    (!finite(bb->vel[0])) || (!finite(bb->vel[1])) || (!finite(bb->vel[2])) )
	{
		zero_v3(bb->vec);
		zero_v3(bb->vel);

		zero_v3(xvec);
		zero_v3(yvec);
		zero_v3(zvec);
		zero_v3(center);

		return;
	}

	if (bb->align < PART_BB_VIEW)
		onevec[bb->align] = 1.0f;

	if (bb->lock && (bb->align == PART_BB_VIEW)) {
		normalize_v3_v3(xvec, bb->ob->obmat[0]);
		normalize_v3_v3(yvec, bb->ob->obmat[1]);
		normalize_v3_v3(zvec, bb->ob->obmat[2]);
	}
	else if (bb->align == PART_BB_VEL) {
		float temp[3];

		normalize_v3_v3(temp, bb->vel);

		sub_v3_v3v3(zvec, bb->ob->obmat[3], bb->vec);

		if (bb->lock) {
			float fac = -dot_v3v3(zvec, temp);

			madd_v3_v3fl(zvec, temp, fac);
		}
		normalize_v3(zvec);

		cross_v3_v3v3(xvec, temp, zvec);
		normalize_v3(xvec);

		cross_v3_v3v3(yvec, zvec, xvec);
	}
	else {
		sub_v3_v3v3(zvec, bb->ob->obmat[3], bb->vec);
		if (bb->lock)
			zvec[bb->align] = 0.0f;
		normalize_v3(zvec);

		if (bb->align < PART_BB_VIEW)
			cross_v3_v3v3(xvec, onevec, zvec);
		else
			cross_v3_v3v3(xvec, bb->ob->obmat[1], zvec);
		normalize_v3(xvec);

		cross_v3_v3v3(yvec, zvec, xvec);
	}

	copy_v3_v3(tvec, xvec);
	copy_v3_v3(tvec2, yvec);

	mul_v3_fl(xvec, cosf(bb->tilt * (float)M_PI));
	mul_v3_fl(tvec2, sinf(bb->tilt * (float)M_PI));
	add_v3_v3(xvec, tvec2);

	mul_v3_fl(yvec, cosf(bb->tilt * (float)M_PI));
	mul_v3_fl(tvec, -sinf(bb->tilt * (float)M_PI));
	add_v3_v3(yvec, tvec);

	mul_v3_fl(xvec, bb->size[0]);
	mul_v3_fl(yvec, bb->size[1]);

	madd_v3_v3v3fl(center, bb->vec, xvec, bb->offset[0]);
	madd_v3_v3fl(center, yvec, bb->offset[1]);
}

void psys_apply_hair_lattice(Scene *scene, Object *ob, ParticleSystem *psys)
{
	ParticleSimulationData sim = {0};
	sim.scene = scene;
	sim.ob = ob;
	sim.psys = psys;
	sim.psmd = psys_get_modifier(ob, psys);

	psys->lattice_deform_data = psys_create_lattice_deform_data(&sim);

	if (psys->lattice_deform_data) {
		ParticleData *pa = psys->particles;
		HairKey *hkey;
		int p, h;
		float hairmat[4][4], imat[4][4];

		for (p = 0; p < psys->totpart; p++, pa++) {
			psys_mat_hair_to_global(sim.ob, sim.psmd->dm, psys->part->from, pa, hairmat);
			invert_m4_m4(imat, hairmat);

			hkey = pa->hair;
			for (h = 0; h < pa->totkey; h++, hkey++) {
				mul_m4_v3(hairmat, hkey->co);
				calc_latt_deform(psys->lattice_deform_data, hkey->co, 1.0f);
				mul_m4_v3(imat, hkey->co);
			}
		}
		
		end_latt_deform(psys->lattice_deform_data);
		psys->lattice_deform_data = NULL;

		/* protect the applied shape */
		psys->flag |= PSYS_EDITED;
	}
}
