// dear imgui: Renderer for modern OpenGL with shaders / programmatic pipeline
// - Desktop GL: 2.x 3.x 4.x
// - Embedded GL: ES 2.0 (WebGL 1.0), ES 3.0 (WebGL 2.0)
// This needs to be used along with a Platform Binding (e.g. GLFW, SDL, Win32, custom..)

// Implemented features:
//  [X] Renderer: User texture binding. Use 'GLuint' OpenGL texture identifier as void*/ImTextureID. Read the FAQ
//  about ImTextureID! [X] Renderer: Multi-viewport support. Enable with 'io.ConfigFlags |=
//  ImGuiConfigFlags_ViewportsEnable'. [x] Renderer: Desktop GL only: Support for large meshes (64k+ vertices) with
//  16-bit indices.

// You can copy and use unmodified imgui_impl_* files in your project. See main.cpp for an example of using this.
// If you are new to dear imgui, read examples/README.txt and read the documentation at the top of imgui.cpp.
// https://github.com/ocornut/imgui

// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
//  2020-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
//  2020-07-10: OpenGL: Added support for glad2 OpenGL loader.
//  2020-05-08: OpenGL: Made default GLSL version 150 (instead of 130) on OSX.
//  2020-04-21: OpenGL: Fixed handling of glClipControl(GL_UPPER_LEFT) by inverting projection matrix.
//  2020-04-12: OpenGL: Fixed context version check mistakenly testing for 4.0+ instead of 3.2+ to enable
//  ImGuiBackendFlags_RendererHasVtxOffset. 2020-03-24: OpenGL: Added support for glbinding 2.x OpenGL loader.
//  2020-01-07: OpenGL: Added support for glbinding 3.x OpenGL loader.
//  2019-10-25: OpenGL: Using a combination of GL define and runtime GL version to decide whether to use
//  glDrawElementsBaseVertex(). Fix building with pre-3.2 GL loaders. 2019-09-22: OpenGL: Detect default GL loader
//  using __has_include compiler facility. 2019-09-16: OpenGL: Tweak initialization code to allow application calling
//  ImGui_ImplOpenGL3_CreateFontsTexture() before the first NewFrame() call. 2019-05-29: OpenGL: Desktop GL only:
//  Added support for large mesh (64K+ vertices), enable ImGuiBackendFlags_RendererHasVtxOffset flag. 2019-04-30:
//  OpenGL: Added support for special ImDrawCallback_ResetRenderState callback to reset render state. 2019-03-29:
//  OpenGL: Not calling glBindBuffer more than necessary in the render loop. 2019-03-15: OpenGL: Added a GL call +
//  comments in ImGui_ImplOpenGL3_Init() to detect uninitialized GL function loaders early. 2019-03-03: OpenGL: Fix
//  support for ES 2.0 (WebGL 1.0). 2019-02-20: OpenGL: Fix for OSX not supporting OpenGL 4.5, we don't try to read
//  GL_CLIP_ORIGIN even if defined by the headers/loader. 2019-02-11: OpenGL: Projecting clipping rectangles correctly
//  using draw_data->FramebufferScale to allow multi-viewports for retina display. 2019-02-01: OpenGL: Using GLSL 410
//  shaders for any version over 410 (e.g. 430, 450). 2018-11-30: Misc: Setting up io.BackendRendererName so it can be
//  displayed in the About Window. 2018-11-13: OpenGL: Support for GL 4.5's glClipControl(GL_UPPER_LEFT) /
//  GL_CLIP_ORIGIN. 2018-08-29: OpenGL: Added support for more OpenGL loaders: glew and glad, with comments indicative
//  that any loader can be used. 2018-08-09: OpenGL: Default to OpenGL ES 3 on iOS and Android. GLSL version default
//  to "#version 300 ES". 2018-07-30: OpenGL: Support for GLSL 300 ES and 410 core. Fixes for Emscripten compilation.
//  2018-07-10: OpenGL: Support for more GLSL versions (based on the GLSL version string). Added error output when
//  shaders fail to compile/link. 2018-06-08: Misc: Extracted imgui_impl_opengl3.cpp/.h away from the old combined
//  GLFW/SDL+OpenGL3 examples. 2018-06-08: OpenGL: Use draw_data->DisplayPos and draw_data->DisplaySize to setup
//  projection matrix and clipping rectangle. 2018-05-25: OpenGL: Removed unnecessary backup/restore of
//  GL_ELEMENT_ARRAY_BUFFER_BINDING since this is part of the VAO state. 2018-05-14: OpenGL: Making the call to
//  glBindSampler() optional so 3.2 context won't fail if the function is a NULL pointer. 2018-03-06: OpenGL: Added
//  const char* glsl_version parameter to ImGui_ImplOpenGL3_Init() so user can override the GLSL version e.g.
//  "#version 150". 2018-02-23: OpenGL: Create the VAO in the render function so the setup can more easily be used
//  with multiple shared GL context. 2018-02-16: Misc: Obsoleted the io.RenderDrawListsFn callback and exposed
//  ImGui_ImplSdlGL3_RenderDrawData() in the .h file so you can call it yourself. 2018-01-07: OpenGL: Changed GLSL
//  shader version from 330 to 150. 2017-09-01: OpenGL: Save and restore current bound sampler. Save and restore
//  current polygon mode. 2017-05-01: OpenGL: Fixed save and restore of current blend func state. 2017-05-01: OpenGL:
//  Fixed save and restore of current GL_ACTIVE_TEXTURE. 2016-09-05: OpenGL: Fixed save and restore of current scissor
//  rectangle. 2016-07-29: OpenGL: Explicitly setting GL_UNPACK_ROW_LENGTH to reduce issues because SDL changes it.
//  (#752)

//----------------------------------------
// OpenGL    GLSL      GLSL
// version   version   string
//----------------------------------------
//  2.0       110       "#version 110"
//  2.1       120       "#version 120"
//  3.0       130       "#version 130"
//  3.1       140       "#version 140"
//  3.2       150       "#version 150"
//  3.3       330       "#version 330 core"
//  4.0       400       "#version 400 core"
//  4.1       410       "#version 410 core"
//  4.2       420       "#version 410 core"
//  4.3       430       "#version 430 core"
//  ES 2.0    100       "#version 100"      = WebGL 1.0
//  ES 3.0    300       "#version 300 es"   = WebGL 2.0
//----------------------------------------

#if defined(_MSC_VER) && !defined(_CRT_SECURE_NO_WARNINGS)
#define _CRT_SECURE_NO_WARNINGS
#endif

#include "imgui_impl_opengl3.h"
#include "imgui.h"
#include <stdio.h>
#if defined(_MSC_VER) && _MSC_VER <= 1500 // MSVC 2008 or earlier
#include <stddef.h>                       // intptr_t
#else
#include <stdint.h> // intptr_t
#endif

// GL includes
#if defined(IMGUI_IMPL_OPENGL_ES2)
#include <GLES2/gl2.h>
#elif defined(IMGUI_IMPL_OPENGL_ES3)
#if (defined(__APPLE__) && (TARGET_OS_IOS || TARGET_OS_TV))
#include <OpenGLES/ES3/gl.h> // Use GL ES 3
#else
#include <GLES3/gl3.h> // Use GL ES 3
#endif
#else
// About Desktop OpenGL function loaders:
//  Modern desktop OpenGL doesn't have a standard portable header file to load OpenGL function pointers.
//  Helper libraries are often used for this purpose! Here we are supporting a few common ones (gl3w, glew, glad).
//  You may use another loader/header of your choice (glext, glLoadGen, etc.), or chose to manually implement your
//  own.
#if defined(IMGUI_IMPL_OPENGL_LOADER_GL3W)
#include <GL/gl3w.h> // Needs to be initialized with gl3wInit() in user's code
#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLEW)
#include <GL/glew.h> // Needs to be initialized with glewInit() in user's code.
#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD)
#include <glad/glad.h> // Needs to be initialized with gladLoadGL() in user's code.
#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD2)
#include <glad/gl.h> // Needs to be initialized with gladLoadGL(...) or gladLoaderLoadGL() in user's code.
#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING2)
#ifndef GLFW_INCLUDE_NONE
#define GLFW_INCLUDE_NONE // GLFW including OpenGL headers causes ambiguity or multiple definition errors.
#endif
#include <glbinding/Binding.h> // Needs to be initialized with glbinding::Binding::initialize() in user's code.
#include <glbinding/gl/gl.h>
using namespace gl;
#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING3)
#ifndef GLFW_INCLUDE_NONE
#define GLFW_INCLUDE_NONE // GLFW including OpenGL headers causes ambiguity or multiple definition errors.
#endif
#include <glbinding/gl/gl.h>
#include <glbinding/glbinding.h> // Needs to be initialized with glbinding::initialize() in user's code.
using namespace gl;
#else
#include IMGUI_IMPL_OPENGL_LOADER_CUSTOM
#endif
#endif

// Desktop GL 3.2+ has glDrawElementsBaseVertex() which GL ES and WebGL don't have.
#if defined(IMGUI_IMPL_OPENGL_ES2) || defined(IMGUI_IMPL_OPENGL_ES3) || !defined(GL_VERSION_3_2)
#define IMGUI_IMPL_OPENGL_MAY_HAVE_VTX_OFFSET 0
#else
#define IMGUI_IMPL_OPENGL_MAY_HAVE_VTX_OFFSET 1
#endif

// OpenGL Data
static GLuint g_GlVersion =
		0; // Extracted at runtime using GL_MAJOR_VERSION, GL_MINOR_VERSION queries (e.g. 320 for GL 3.2)
static char g_GlslVersionString[32] = ""; // Specified by user or detected based on compile time GL settings.
static GLuint g_FontTexture = 0;
static GLuint g_ShaderHandle = 0, g_VertHandle = 0, g_FragHandle = 0;
static GLint g_AttribLocationTex = 0, g_AttribLocationProjMtx = 0; // Uniforms location
static GLuint g_AttribLocationVtxPos = 0, g_AttribLocationVtxUV = 0,
							g_AttribLocationVtxColor = 0; // Vertex attributes location
static unsigned int g_VboHandle = 0, g_ElementsHandle = 0;

// Forward Declarations
static void ImGui_ImplOpenGL3_InitPlatformInterface();
static void ImGui_ImplOpenGL3_ShutdownPlatformInterface();

// Functions
bool ImGui_ImplOpenGL3_Init(const char* glsl_version)
{
	// Query for GL version (e.g. 320 for GL 3.2)
#if !defined(IMGUI_IMPL_OPENGL_ES2)
	GLint major, minor;
	glGetIntegerv(GL_MAJOR_VERSION, &major);
	glGetIntegerv(GL_MINOR_VERSION, &minor);
	g_GlVersion = (GLuint)(major * 100 + minor * 10);
#else
	g_GlVersion = 200; // GLES 2
#endif

	// Setup back-end capabilities flags
	ImGuiIO& io = ImGui::GetIO();
	io.BackendRendererName = "imgui_impl_opengl3";
#if IMGUI_IMPL_OPENGL_MAY_HAVE_VTX_OFFSET
	if (g_GlVersion >= 320)
		io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset; // We can honor the ImDrawCmd::VtxOffset field,
		                                                           // allowing for large meshes.
#endif
	io.BackendFlags |=
			ImGuiBackendFlags_RendererHasViewports; // We can create multi-viewports on the Renderer side (optional)

	// Store GLSL version string so we can refer to it later in case we recreate shaders.
	// Note: GLSL version is NOT the same as GL version. Leave this to NULL if unsure.
#if defined(IMGUI_IMPL_OPENGL_ES2)
	if (glsl_version == NULL)
		glsl_version = "#version 100";
#elif defined(IMGUI_IMPL_OPENGL_ES3)
	if (glsl_version == NULL)
		glsl_version = "#version 300 es";
#elif defined(__APPLE__)
	if (glsl_version == NULL)
		glsl_version = "#version 150";
#else
	if (glsl_version == NULL)
		glsl_version = "#version 130";
#endif
	IM_ASSERT((int)strlen(glsl_version) + 2 < IM_ARRAYSIZE(g_GlslVersionString));
	strcpy(g_GlslVersionString, glsl_version);
	strcat(g_GlslVersionString, "\n");

	// Debugging construct to make it easily visible in the IDE and debugger which GL loader has been selected.
	// The code actually never uses the 'gl_loader' variable! It is only here so you can read it!
	// If auto-detection fails or doesn't select the same GL loader file as used by your application,
	// you are likely to get a crash below.
	// You can explicitly select a loader by using '#define IMGUI_IMPL_OPENGL_LOADER_XXX' in imconfig.h or compiler
	// command-line.
	const char* gl_loader = "Unknown";
	IM_UNUSED(gl_loader);
#if defined(IMGUI_IMPL_OPENGL_LOADER_GL3W)
	gl_loader = "GL3W";
#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLEW)
	gl_loader = "GLEW";
#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD)
	gl_loader = "GLAD";
#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD2)
	gl_loader = "GLAD2";
#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING2)
	gl_loader = "glbinding2";
#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING3)
	gl_loader = "glbinding3";
#elif defined(IMGUI_IMPL_OPENGL_LOADER_CUSTOM)
	gl_loader = "custom";
#else
	gl_loader = "none";
#endif

	// Make an arbitrary GL call (we don't actually need the result)
	// IF YOU GET A CRASH HERE: it probably means that you haven't initialized the OpenGL function loader used by this
	// code. Desktop OpenGL 3/4 need a function loader. See the IMGUI_IMPL_OPENGL_LOADER_xxx explanation above.
	GLint current_texture;
	glGetIntegerv(GL_TEXTURE_BINDING_2D, &current_texture);

	if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
		ImGui_ImplOpenGL3_InitPlatformInterface();

	return true;
}

void ImGui_ImplOpenGL3_Shutdown()
{
	ImGui_ImplOpenGL3_ShutdownPlatformInterface();
	ImGui_ImplOpenGL3_DestroyDeviceObjects();
}

void ImGui_ImplOpenGL3_NewFrame()
{
	if (!g_ShaderHandle)
		ImGui_ImplOpenGL3_CreateDeviceObjects();
}

static void ImGui_ImplOpenGL3_SetupRenderState(ImDrawData* draw_data, int fb_width, int fb_height,
                                               GLuint vertex_array_object)
{
	// Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled, polygon fill
	glEnable(GL_BLEND);
	glBlendEquation(GL_FUNC_ADD);
	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
	glDisable(GL_CULL_FACE);
	glDisable(GL_DEPTH_TEST);
	glEnable(GL_SCISSOR_TEST);
#ifdef GL_POLYGON_MODE
	glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
#endif

	// Support for GL 4.5 rarely used glClipControl(GL_UPPER_LEFT)
	bool clip_origin_lower_left = true;
#if defined(GL_CLIP_ORIGIN) && !defined(__APPLE__)
	GLenum current_clip_origin = 0;
	glGetIntegerv(GL_CLIP_ORIGIN, (GLint*)&current_clip_origin);
	if (current_clip_origin == GL_UPPER_LEFT)
		clip_origin_lower_left = false;
#endif

	// Setup viewport, orthographic projection matrix
	// Our visible imgui space lies from draw_data->DisplayPos (top left) to
	// draw_data->DisplayPos+data_data->DisplaySize (bottom right). DisplayPos is (0,0) for single viewport apps.
	glViewport(0, 0, (GLsizei)fb_width, (GLsizei)fb_height);
	float L = draw_data->DisplayPos.x;
	float R = draw_data->DisplayPos.x + draw_data->DisplaySize.x;
	float T = draw_data->DisplayPos.y;
	float B = draw_data->DisplayPos.y + draw_data->DisplaySize.y;
	if (!clip_origin_lower_left)
	{
		float tmp = T;
		T = B;
		B = tmp;
	} // Swap top and bottom if origin is upper left
	const float ortho_projection[4][4] = {
			{2.0f / (R - L), 0.0f, 0.0f, 0.0f},
			{0.0f, 2.0f / (T - B), 0.0f, 0.0f},
			{0.0f, 0.0f, -1.0f, 0.0f},
			{(R + L) / (L - R), (T + B) / (B - T), 0.0f, 1.0f},
	};
	glUseProgram(g_ShaderHandle);
	glUniform1i(g_AttribLocationTex, 0);
	glUniformMatrix4fv(g_AttribLocationProjMtx, 1, GL_FALSE, &ortho_projection[0][0]);
#ifdef GL_SAMPLER_BINDING
	glBindSampler(0, 0); // We use combined texture/sampler state. Applications using GL 3.3 may set that otherwise.
#endif

	(void)vertex_array_object;
#ifndef IMGUI_IMPL_OPENGL_ES2
	glBindVertexArray(vertex_array_object);
#endif

	// Bind vertex/index buffers and setup attributes for ImDrawVert
	glBindBuffer(GL_ARRAY_BUFFER, g_VboHandle);
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, g_ElementsHandle);
	glEnableVertexAttribArray(g_AttribLocationVtxPos);
	glEnableVertexAttribArray(g_AttribLocationVtxUV);
	glEnableVertexAttribArray(g_AttribLocationVtxColor);
	glVertexAttribPointer(g_AttribLocationVtxPos, 2, GL_FLOAT, GL_FALSE, sizeof(ImDrawVert),
	                      (GLvoid*)IM_OFFSETOF(ImDrawVert, pos));
	glVertexAttribPointer(g_AttribLocationVtxUV, 2, GL_FLOAT, GL_FALSE, sizeof(ImDrawVert),
	                      (GLvoid*)IM_OFFSETOF(ImDrawVert, uv));
	glVertexAttribPointer(g_AttribLocationVtxColor, 4, GL_UNSIGNED_BYTE, GL_TRUE, sizeof(ImDrawVert),
	                      (GLvoid*)IM_OFFSETOF(ImDrawVert, col));
}

// OpenGL3 Render function.
// (this used to be set in io.RenderDrawListsFn and called by ImGui::Render(), but you can now call this directly from
// your main loop) Note that this implementation is little overcomplicated because we are saving/setting up/restoring
// every OpenGL state explicitly, in order to be able to run within any OpenGL engine that doesn't do so.
void ImGui_ImplOpenGL3_RenderDrawData(ImDrawData* draw_data)
{
	// Avoid rendering when minimized, scale coordinates for retina displays (screen coordinates != framebuffer
	// coordinates)
	int fb_width = (int)(draw_data->DisplaySize.x * draw_data->FramebufferScale.x);
	int fb_height = (int)(draw_data->DisplaySize.y * draw_data->FramebufferScale.y);
	if (fb_width <= 0 || fb_height <= 0)
		return;

	// Backup GL state
	GLenum last_active_texture;
	glGetIntegerv(GL_ACTIVE_TEXTURE, (GLint*)&last_active_texture);
	glActiveTexture(GL_TEXTURE0);
	GLuint last_program;
	glGetIntegerv(GL_CURRENT_PROGRAM, (GLint*)&last_program);
	GLuint last_texture;
	glGetIntegerv(GL_TEXTURE_BINDING_2D, (GLint*)&last_texture);
#ifdef GL_SAMPLER_BINDING
	GLuint last_sampler;
	glGetIntegerv(GL_SAMPLER_BINDING, (GLint*)&last_sampler);
#endif
	GLuint last_array_buffer;
	glGetIntegerv(GL_ARRAY_BUFFER_BINDING, (GLint*)&last_array_buffer);
#ifndef IMGUI_IMPL_OPENGL_ES2
	GLuint last_vertex_array_object;
	glGetIntegerv(GL_VERTEX_ARRAY_BINDING, (GLint*)&last_vertex_array_object);
#endif
#ifdef GL_POLYGON_MODE
	GLint last_polygon_mode[2];
	glGetIntegerv(GL_POLYGON_MODE, last_polygon_mode);
#endif
	GLint last_viewport[4];
	glGetIntegerv(GL_VIEWPORT, last_viewport);
	GLint last_scissor_box[4];
	glGetIntegerv(GL_SCISSOR_BOX, last_scissor_box);
	GLenum last_blend_src_rgb;
	glGetIntegerv(GL_BLEND_SRC_RGB, (GLint*)&last_blend_src_rgb);
	GLenum last_blend_dst_rgb;
	glGetIntegerv(GL_BLEND_DST_RGB, (GLint*)&last_blend_dst_rgb);
	GLenum last_blend_src_alpha;
	glGetIntegerv(GL_BLEND_SRC_ALPHA, (GLint*)&last_blend_src_alpha);
	GLenum last_blend_dst_alpha;
	glGetIntegerv(GL_BLEND_DST_ALPHA, (GLint*)&last_blend_dst_alpha);
	GLenum last_blend_equation_rgb;
	glGetIntegerv(GL_BLEND_EQUATION_RGB, (GLint*)&last_blend_equation_rgb);
	GLenum last_blend_equation_alpha;
	glGetIntegerv(GL_BLEND_EQUATION_ALPHA, (GLint*)&last_blend_equation_alpha);
	GLboolean last_enable_blend = glIsEnabled(GL_BLEND);
	GLboolean last_enable_cull_face = glIsEnabled(GL_CULL_FACE);
	GLboolean last_enable_depth_test = glIsEnabled(GL_DEPTH_TEST);
	GLboolean last_enable_scissor_test = glIsEnabled(GL_SCISSOR_TEST);

	// Setup desired GL state
	// Recreate the VAO every time (this is to easily allow multiple GL contexts to be rendered to. VAO are not shared
	// among GL contexts) The renderer would actually work without any VAO bound, but then our VertexAttrib calls would
	// overwrite the default one currently bound.
	GLuint vertex_array_object = 0;
#ifndef IMGUI_IMPL_OPENGL_ES2
	glGenVertexArrays(1, &vertex_array_object);
#endif
	ImGui_ImplOpenGL3_SetupRenderState(draw_data, fb_width, fb_height, vertex_array_object);

	// Will project scissor/clipping rectangles into framebuffer space
	ImVec2 clip_off = draw_data->DisplayPos;         // (0,0) unless using multi-viewports
	ImVec2 clip_scale = draw_data->FramebufferScale; // (1,1) unless using retina display which are often (2,2)

	// Render command lists
	for (int n = 0; n < draw_data->CmdListsCount; n++)
	{
		const ImDrawList* cmd_list = draw_data->CmdLists[n];

		// Upload vertex/index buffers
		glBufferData(GL_ARRAY_BUFFER, (GLsizeiptr)cmd_list->VtxBuffer.Size * (int)sizeof(ImDrawVert),
		             (const GLvoid*)cmd_list->VtxBuffer.Data, GL_STREAM_DRAW);
		glBufferData(GL_ELEMENT_ARRAY_BUFFER, (GLsizeiptr)cmd_list->IdxBuffer.Size * (int)sizeof(ImDrawIdx),
		             (const GLvoid*)cmd_list->IdxBuffer.Data, GL_STREAM_DRAW);

		for (int cmd_i = 0; cmd_i < cmd_list->CmdBuffer.Size; cmd_i++)
		{
			const ImDrawCmd* pcmd = &cmd_list->CmdBuffer[cmd_i];
			if (pcmd->UserCallback != NULL)
			{
				// User callback, registered via ImDrawList::AddCallback()
				// (ImDrawCallback_ResetRenderState is a special callback value used by the user to request the renderer to
				// reset render state.)
				if (pcmd->UserCallback == ImDrawCallback_ResetRenderState)
					ImGui_ImplOpenGL3_SetupRenderState(draw_data, fb_width, fb_height, vertex_array_object);
				else
					pcmd->UserCallback(cmd_list, pcmd);
			}
			else
			{
				// Project scissor/clipping rectangles into framebuffer space
				ImVec4 clip_rect;
				clip_rect.x = (pcmd->ClipRect.x - clip_off.x) * clip_scale.x;
				clip_rect.y = (pcmd->ClipRect.y - clip_off.y) * clip_scale.y;
				clip_rect.z = (pcmd->ClipRect.z - clip_off.x) * clip_scale.x;
				clip_rect.w = (pcmd->ClipRect.w - clip_off.y) * clip_scale.y;

				if (clip_rect.x < fb_width && clip_rect.y < fb_height && clip_rect.z >= 0.0f && clip_rect.w >= 0.0f)
				{
					// Apply scissor/clipping rectangle
					glScissor((int)clip_rect.x, (int)(fb_height - clip_rect.w), (int)(clip_rect.z - clip_rect.x),
					          (int)(clip_rect.w - clip_rect.y));

					// Bind texture, Draw
					glBindTexture(GL_TEXTURE_2D, (GLuint)(intptr_t)pcmd->TextureId);
#if IMGUI_IMPL_OPENGL_MAY_HAVE_VTX_OFFSET
					if (g_GlVersion >= 320)
						glDrawElementsBaseVertex(GL_TRIANGLES, (GLsizei)pcmd->ElemCount,
						                         sizeof(ImDrawIdx) == 2 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_INT,
						                         (void*)(intptr_t)(pcmd->IdxOffset * sizeof(ImDrawIdx)), (GLint)pcmd->VtxOffset);
					else
#endif
						glDrawElements(GL_TRIANGLES, (GLsizei)pcmd->ElemCount,
						               sizeof(ImDrawIdx) == 2 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_INT,
						               (void*)(intptr_t)(pcmd->IdxOffset * sizeof(ImDrawIdx)));
				}
			}
		}
	}

	// Destroy the temporary VAO
#ifndef IMGUI_IMPL_OPENGL_ES2
	glDeleteVertexArrays(1, &vertex_array_object);
#endif

	// Restore modified GL state
	glUseProgram(last_program);
	glBindTexture(GL_TEXTURE_2D, last_texture);
#ifdef GL_SAMPLER_BINDING
	glBindSampler(0, last_sampler);
#endif
	glActiveTexture(last_active_texture);
#ifndef IMGUI_IMPL_OPENGL_ES2
	glBindVertexArray(last_vertex_array_object);
#endif
	glBindBuffer(GL_ARRAY_BUFFER, last_array_buffer);
	glBlendEquationSeparate(last_blend_equation_rgb, last_blend_equation_alpha);
	glBlendFuncSeparate(last_blend_src_rgb, last_blend_dst_rgb, last_blend_src_alpha, last_blend_dst_alpha);
	if (last_enable_blend)
		glEnable(GL_BLEND);
	else
		glDisable(GL_BLEND);
	if (last_enable_cull_face)
		glEnable(GL_CULL_FACE);
	else
		glDisable(GL_CULL_FACE);
	if (last_enable_depth_test)
		glEnable(GL_DEPTH_TEST);
	else
		glDisable(GL_DEPTH_TEST);
	if (last_enable_scissor_test)
		glEnable(GL_SCISSOR_TEST);
	else
		glDisable(GL_SCISSOR_TEST);
#ifdef GL_POLYGON_MODE
	glPolygonMode(GL_FRONT_AND_BACK, (GLenum)last_polygon_mode[0]);
#endif
	glViewport(last_viewport[0], last_viewport[1], (GLsizei)last_viewport[2], (GLsizei)last_viewport[3]);
	glScissor(last_scissor_box[0], last_scissor_box[1], (GLsizei)last_scissor_box[2], (GLsizei)last_scissor_box[3]);
}

bool ImGui_ImplOpenGL3_CreateFontsTexture()
{
	// Build texture atlas
	ImGuiIO& io = ImGui::GetIO();
	unsigned char* pixels;
	int width, height;
	io.Fonts->GetTexDataAsRGBA32(
			&pixels, &width, &height); // Load as RGBA 32-bit (75% of the memory is wasted, but default font is so small)
	                               // because it is more likely to be compatible with user's existing shaders. If your
	                               // ImTextureId represent a higher-level concept than just a GL texture id, consider
	                               // calling GetTexDataAsAlpha8() instead to save on GPU memory.

	// Upload texture to graphics system
	GLint last_texture;
	glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture);
	glGenTextures(1, &g_FontTexture);
	glBindTexture(GL_TEXTURE_2D, g_FontTexture);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
#ifdef GL_UNPACK_ROW_LENGTH
	glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
#endif
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, pixels);

	// Store our identifier
	io.Fonts->TexID = (ImTextureID)(intptr_t)g_FontTexture;

	// Restore state
	glBindTexture(GL_TEXTURE_2D, last_texture);

	return true;
}

void ImGui_ImplOpenGL3_DestroyFontsTexture()
{
	if (g_FontTexture)
	{
		ImGuiIO& io = ImGui::GetIO();
		glDeleteTextures(1, &g_FontTexture);
		io.Fonts->TexID = 0;
		g_FontTexture = 0;
	}
}

// If you get an error please report on github. You may try different GL context version or GLSL version. See GL<>GLSL
// version table at the top of this file.
static bool CheckShader(GLuint handle, const char* desc)
{
	GLint status = 0, log_length = 0;
	glGetShaderiv(handle, GL_COMPILE_STATUS, &status);
	glGetShaderiv(handle, GL_INFO_LOG_LENGTH, &log_length);
	if ((GLboolean)status == GL_FALSE)
		fprintf(stderr, "ERROR: ImGui_ImplOpenGL3_CreateDeviceObjects: failed to compile %s!\n", desc);
	if (log_length > 1)
	{
		ImVector<char> buf;
		buf.resize((int)(log_length + 1));
		glGetShaderInfoLog(handle, log_length, NULL, (GLchar*)buf.begin());
		fprintf(stderr, "%s\n", buf.begin());
	}
	return (GLboolean)status == GL_TRUE;
}

// If you get an error please report on GitHub. You may try different GL context version or GLSL version.
static bool CheckProgram(GLuint handle, const char* desc)
{
	GLint status = 0, log_length = 0;
	glGetProgramiv(handle, GL_LINK_STATUS, &status);
	glGetProgramiv(handle, GL_INFO_LOG_LENGTH, &log_length);
	if ((GLboolean)status == GL_FALSE)
		fprintf(stderr, "ERROR: ImGui_ImplOpenGL3_CreateDeviceObjects: failed to link %s! (with GLSL '%s')\n", desc,
		        g_GlslVersionString);
	if (log_length > 1)
	{
		ImVector<char> buf;
		buf.resize((int)(log_length + 1));
		glGetProgramInfoLog(handle, log_length, NULL, (GLchar*)buf.begin());
		fprintf(stderr, "%s\n", buf.begin());
	}
	return (GLboolean)status == GL_TRUE;
}

bool ImGui_ImplOpenGL3_CreateDeviceObjects()
{
	// Backup GL state
	GLint last_texture, last_array_buffer;
	glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture);
	glGetIntegerv(GL_ARRAY_BUFFER_BINDING, &last_array_buffer);
#ifndef IMGUI_IMPL_OPENGL_ES2
	GLint last_vertex_array;
	glGetIntegerv(GL_VERTEX_ARRAY_BINDING, &last_vertex_array);
#endif

	// Parse GLSL version string
	int glsl_version = 130;
	sscanf(g_GlslVersionString, "#version %d", &glsl_version);

	const GLchar* vertex_shader_glsl_120 = "uniform mat4 ProjMtx;\n"
																				 "attribute vec2 Position;\n"
																				 "attribute vec2 UV;\n"
																				 "attribute vec4 Color;\n"
																				 "varying vec2 Frag_UV;\n"
																				 "varying vec4 Frag_Color;\n"
																				 "void main()\n"
																				 "{\n"
																				 "    Frag_UV = UV;\n"
																				 "    Frag_Color = Color;\n"
																				 "    gl_Position = ProjMtx * vec4(Position.xy,0,1);\n"
																				 "}\n";

	const GLchar* vertex_shader_glsl_130 = "uniform mat4 ProjMtx;\n"
																				 "in vec2 Position;\n"
																				 "in vec2 UV;\n"
																				 "in vec4 Color;\n"
																				 "out vec2 Frag_UV;\n"
																				 "out vec4 Frag_Color;\n"
																				 "void main()\n"
																				 "{\n"
																				 "    Frag_UV = UV;\n"
																				 "    Frag_Color = Color;\n"
																				 "    gl_Position = ProjMtx * vec4(Position.xy,0,1);\n"
																				 "}\n";

	const GLchar* vertex_shader_glsl_300_es = "precision mediump float;\n"
																						"layout (location = 0) in vec2 Position;\n"
																						"layout (location = 1) in vec2 UV;\n"
																						"layout (location = 2) in vec4 Color;\n"
																						"uniform mat4 ProjMtx;\n"
																						"out vec2 Frag_UV;\n"
																						"out vec4 Frag_Color;\n"
																						"void main()\n"
																						"{\n"
																						"    Frag_UV = UV;\n"
																						"    Frag_Color = Color;\n"
																						"    gl_Position = ProjMtx * vec4(Position.xy,0,1);\n"
																						"}\n";

	const GLchar* vertex_shader_glsl_410_core = "layout (location = 0) in vec2 Position;\n"
																							"layout (location = 1) in vec2 UV;\n"
																							"layout (location = 2) in vec4 Color;\n"
																							"uniform mat4 ProjMtx;\n"
																							"out vec2 Frag_UV;\n"
																							"out vec4 Frag_Color;\n"
																							"void main()\n"
																							"{\n"
																							"    Frag_UV = UV;\n"
																							"    Frag_Color = Color;\n"
																							"    gl_Position = ProjMtx * vec4(Position.xy,0,1);\n"
																							"}\n";

	const GLchar* fragment_shader_glsl_120 = "#ifdef GL_ES\n"
																					 "    precision mediump float;\n"
																					 "#endif\n"
																					 "uniform sampler2D Texture;\n"
																					 "varying vec2 Frag_UV;\n"
																					 "varying vec4 Frag_Color;\n"
																					 "void main()\n"
																					 "{\n"
																					 "    gl_FragColor = Frag_Color * texture2D(Texture, Frag_UV.st);\n"
																					 "}\n";

	const GLchar* fragment_shader_glsl_130 = "uniform sampler2D Texture;\n"
																					 "in vec2 Frag_UV;\n"
																					 "in vec4 Frag_Color;\n"
																					 "out vec4 Out_Color;\n"
																					 "void main()\n"
																					 "{\n"
																					 "    Out_Color = Frag_Color * texture(Texture, Frag_UV.st);\n"
																					 "}\n";

	const GLchar* fragment_shader_glsl_300_es = "precision mediump float;\n"
																							"uniform sampler2D Texture;\n"
																							"in vec2 Frag_UV;\n"
																							"in vec4 Frag_Color;\n"
																							"layout (location = 0) out vec4 Out_Color;\n"
																							"void main()\n"
																							"{\n"
																							"    Out_Color = Frag_Color * texture(Texture, Frag_UV.st);\n"
																							"}\n";

	const GLchar* fragment_shader_glsl_410_core = "in vec2 Frag_UV;\n"
																								"in vec4 Frag_Color;\n"
																								"uniform sampler2D Texture;\n"
																								"layout (location = 0) out vec4 Out_Color;\n"
																								"void main()\n"
																								"{\n"
																								"    Out_Color = Frag_Color * texture(Texture, Frag_UV.st);\n"
																								"}\n";

	// Select shaders matching our GLSL versions
	const GLchar* vertex_shader = NULL;
	const GLchar* fragment_shader = NULL;
	if (glsl_version < 130)
	{
		vertex_shader = vertex_shader_glsl_120;
		fragment_shader = fragment_shader_glsl_120;
	}
	else if (glsl_version >= 410)
	{
		vertex_shader = vertex_shader_glsl_410_core;
		fragment_shader = fragment_shader_glsl_410_core;
	}
	else if (glsl_version == 300)
	{
		vertex_shader = vertex_shader_glsl_300_es;
		fragment_shader = fragment_shader_glsl_300_es;
	}
	else
	{
		vertex_shader = vertex_shader_glsl_130;
		fragment_shader = fragment_shader_glsl_130;
	}

	// Create shaders
	const GLchar* vertex_shader_with_version[2] = {g_GlslVersionString, vertex_shader};
	g_VertHandle = glCreateShader(GL_VERTEX_SHADER);
	glShaderSource(g_VertHandle, 2, vertex_shader_with_version, NULL);
	glCompileShader(g_VertHandle);
	CheckShader(g_VertHandle, "vertex shader");

	const GLchar* fragment_shader_with_version[2] = {g_GlslVersionString, fragment_shader};
	g_FragHandle = glCreateShader(GL_FRAGMENT_SHADER);
	glShaderSource(g_FragHandle, 2, fragment_shader_with_version, NULL);
	glCompileShader(g_FragHandle);
	CheckShader(g_FragHandle, "fragment shader");

	g_ShaderHandle = glCreateProgram();
	glAttachShader(g_ShaderHandle, g_VertHandle);
	glAttachShader(g_ShaderHandle, g_FragHandle);
	glLinkProgram(g_ShaderHandle);
	CheckProgram(g_ShaderHandle, "shader program");

	g_AttribLocationTex = glGetUniformLocation(g_ShaderHandle, "Texture");
	g_AttribLocationProjMtx = glGetUniformLocation(g_ShaderHandle, "ProjMtx");
	g_AttribLocationVtxPos = (GLuint)glGetAttribLocation(g_ShaderHandle, "Position");
	g_AttribLocationVtxUV = (GLuint)glGetAttribLocation(g_ShaderHandle, "UV");
	g_AttribLocationVtxColor = (GLuint)glGetAttribLocation(g_ShaderHandle, "Color");

	// Create buffers
	glGenBuffers(1, &g_VboHandle);
	glGenBuffers(1, &g_ElementsHandle);

	ImGui_ImplOpenGL3_CreateFontsTexture();

	// Restore modified GL state
	glBindTexture(GL_TEXTURE_2D, last_texture);
	glBindBuffer(GL_ARRAY_BUFFER, last_array_buffer);
#ifndef IMGUI_IMPL_OPENGL_ES2
	glBindVertexArray(last_vertex_array);
#endif

	return true;
}

void ImGui_ImplOpenGL3_DestroyDeviceObjects()
{
	if (g_VboHandle)
	{
		glDeleteBuffers(1, &g_VboHandle);
		g_VboHandle = 0;
	}
	if (g_ElementsHandle)
	{
		glDeleteBuffers(1, &g_ElementsHandle);
		g_ElementsHandle = 0;
	}
	if (g_ShaderHandle && g_VertHandle)
	{
		glDetachShader(g_ShaderHandle, g_VertHandle);
	}
	if (g_ShaderHandle && g_FragHandle)
	{
		glDetachShader(g_ShaderHandle, g_FragHandle);
	}
	if (g_VertHandle)
	{
		glDeleteShader(g_VertHandle);
		g_VertHandle = 0;
	}
	if (g_FragHandle)
	{
		glDeleteShader(g_FragHandle);
		g_FragHandle = 0;
	}
	if (g_ShaderHandle)
	{
		glDeleteProgram(g_ShaderHandle);
		g_ShaderHandle = 0;
	}

	ImGui_ImplOpenGL3_DestroyFontsTexture();
}

//--------------------------------------------------------------------------------------------------------
// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
// This is an _advanced_ and _optional_ feature, allowing the back-end to create and handle multiple viewports
// simultaneously. If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you
// completely ignore this section first..
//--------------------------------------------------------------------------------------------------------

static void ImGui_ImplOpenGL3_RenderWindow(ImGuiViewport* viewport, void*)
{
	if (!(viewport->Flags & ImGuiViewportFlags_NoRendererClear))
	{
		ImVec4 clear_color = ImVec4(0.0f, 0.0f, 0.0f, 1.0f);
		glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
		glClear(GL_COLOR_BUFFER_BIT);
	}
	ImGui_ImplOpenGL3_RenderDrawData(viewport->DrawData);
}

static void ImGui_ImplOpenGL3_InitPlatformInterface()
{
	ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
	platform_io.Renderer_RenderWindow = ImGui_ImplOpenGL3_RenderWindow;
}

static void ImGui_ImplOpenGL3_ShutdownPlatformInterface()
{
	ImGui::DestroyPlatformWindows();
}
