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#
#  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.
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# ##### END GPL LICENSE BLOCK #####

# <pep8 compliant>

import bpy


def create_and_link_mesh(name, faces, points, global_matrix):
    """
    Create a blender mesh and object called name from a list of
    *points* and *faces* and link it in the current scene.
    """

    mesh = bpy.data.meshes.new(name)
    mesh.from_pydata(points, [], faces)
    mesh.transform(global_matrix)

    # update mesh to allow proper display
    mesh.validate()
    mesh.update()

    scene = bpy.context.scene

    obj = bpy.data.objects.new(name, mesh)
    scene.objects.link(obj)
    scene.objects.active = obj
    obj.select = True


def faces_from_mesh(ob, global_matrix, use_mesh_modifiers=False, triangulate=True):
    """
    From an object, return a generator over a list of faces.

    Each faces is a list of his vertexes. Each vertex is a tuple of
    his coordinate.

    use_mesh_modifiers
        Apply the preview modifier to the returned liste

    triangulate
        Split the quad into two triangles
    """

    # get the editmode data
    ob.update_from_editmode()

    # get the modifiers
    try:
        mesh = ob.to_mesh(bpy.context.scene, use_mesh_modifiers, "PREVIEW")
    except RuntimeError:
        raise StopIteration

    mesh.transform(global_matrix * ob.matrix_world)

    if triangulate:
        # From a list of faces, return the face triangulated if needed.
        def iter_face_index():
            for face in mesh.tessfaces:
                vertices = face.vertices[:]
                if len(vertices) == 4:
                    yield vertices[0], vertices[1], vertices[2]
                    yield vertices[2], vertices[3], vertices[0]
                else:
                    yield vertices
    else:
        def iter_face_index():
            for face in mesh.tessfaces:
                yield face.vertices[:]

    vertices = mesh.vertices

    for indexes in iter_face_index():
        yield [vertices[index].co.copy() for index in indexes]

    bpy.data.meshes.remove(mesh)
