import_fbx.py

            edges_conv[edge_index] = e_a
            edges_conv[edge_index + 1] = e_b
            edge_index += 2

        mesh.edges.add(tot_edges)
        mesh.edges.foreach_set("vertices", edges_conv)

    # must be after edge, face loading.
    ok_smooth = blen_read_geom_layer_smooth(fbx_obj, mesh)

    if geom_mat_no is None:
        ok_normals = blen_read_geom_layer_normal(fbx_obj, mesh)
    else:
        def nortrans(v):
            return geom_mat_no * Vector(v)
        ok_normals = blen_read_geom_layer_normal(fbx_obj, mesh, nortrans)

    mesh.validate()

    if not ok_normals:
        mesh.calc_normals()

    if not ok_smooth:
        for p in mesh.polygons:
            p.use_smooth = True

    if settings.use_custom_props:
        blen_read_custom_properties(fbx_obj, mesh, settings)

    return mesh


def blen_read_shape(fbx_tmpl, fbx_sdata, fbx_bcdata, meshes, scene):
    from mathutils import Vector

    elem_name_utf8 = elem_name_ensure_class(fbx_sdata, b'Geometry')
    indices = elem_prop_first(elem_find_first(fbx_sdata, b'Indexes'), default=())
    dvcos = tuple(co for co in zip(*[iter(elem_prop_first(elem_find_first(fbx_sdata, b'Vertices'), default=()))] * 3))
    # We completely ignore normals here!
    weight = elem_prop_first(elem_find_first(fbx_bcdata, b'DeformPercent'), default=100.0) / 100.0
    vgweights = tuple(vgw / 100.0 for vgw in elem_prop_first(elem_find_first(fbx_bcdata, b'FullWeights'), default=()))

    # Special case, in case all weights are the same, FullWeight can have only one element - *sigh!*
    nbr_indices = len(indices)
    if len(vgweights) == 1 and nbr_indices > 1:
        vgweights = (vgweights[0],) * nbr_indices

    assert(len(vgweights) == nbr_indices == len(dvcos))
    create_vg = bool(set(vgweights) - {1.0})

    keyblocks = []

    for me, objects in meshes:
        vcos = tuple((idx, me.vertices[idx].co + Vector(dvco)) for idx, dvco in zip(indices, dvcos))
        objects = list({node.bl_obj for node in objects})
        assert(objects)

        if me.shape_keys is None:
            objects[0].shape_key_add(name="Basis", from_mix=False)
        objects[0].shape_key_add(name=elem_name_utf8, from_mix=False)
        me.shape_keys.use_relative = True  # Should already be set as such.

        kb = me.shape_keys.key_blocks[elem_name_utf8]
        for idx, co in vcos:
            kb.data[idx].co[:] = co
        kb.value = weight

        # Add vgroup if necessary.
        if create_vg:
            add_vgroup_to_objects(indices, vgweights, elem_name_utf8, objects)
            kb.vertex_group = elem_name_utf8

        keyblocks.append(kb)

    return keyblocks


# --------
# Material

def blen_read_material(fbx_tmpl, fbx_obj, settings):
    elem_name_utf8 = elem_name_ensure_class(fbx_obj, b'Material')

    cycles_material_wrap_map = settings.cycles_material_wrap_map
    ma = bpy.data.materials.new(name=elem_name_utf8)

    const_color_white = 1.0, 1.0, 1.0

    fbx_props = (elem_find_first(fbx_obj, b'Properties70'),
                 elem_find_first(fbx_tmpl, b'Properties70', fbx_elem_nil))
    assert(fbx_props[0] is not None)

    ma_diff = elem_props_get_color_rgb(fbx_props, b'DiffuseColor', const_color_white)
    ma_spec = elem_props_get_color_rgb(fbx_props, b'SpecularColor', const_color_white)
    ma_alpha = elem_props_get_number(fbx_props, b'Opacity', 1.0)
    ma_spec_intensity = ma.specular_intensity = elem_props_get_number(fbx_props, b'SpecularFactor', 0.25) * 2.0
    ma_spec_hardness = elem_props_get_number(fbx_props, b'Shininess', 9.6)
    ma_refl_factor = elem_props_get_number(fbx_props, b'ReflectionFactor', 0.0)
    ma_refl_color = elem_props_get_color_rgb(fbx_props, b'ReflectionColor', const_color_white)

    if settings.use_cycles:
        from . import cycles_shader_compat
        # viewport color
        ma.diffuse_color = ma_diff

        ma_wrap = cycles_shader_compat.CyclesShaderWrapper(ma)
        ma_wrap.diffuse_color_set(ma_diff)
        ma_wrap.specular_color_set([c * ma_spec_intensity for c in ma_spec])
        ma_wrap.hardness_value_set(((ma_spec_hardness + 3.0) / 5.0) - 0.65)
        ma_wrap.alpha_value_set(ma_alpha)
        ma_wrap.reflect_factor_set(ma_refl_factor)
        ma_wrap.reflect_color_set(ma_refl_color)

        cycles_material_wrap_map[ma] = ma_wrap
    else:
        # TODO, number BumpFactor isnt used yet
        ma.diffuse_color = ma_diff
        ma.specular_color = ma_spec
        ma.alpha = ma_alpha
        ma.specular_intensity = ma_spec_intensity
        ma.specular_hardness = ma_spec_hardness * 5.10 + 1.0

        if ma_refl_factor != 0.0:
            ma.raytrace_mirror.use = True
            ma.raytrace_mirror.reflect_factor = ma_refl_factor
            ma.mirror_color = ma_refl_color

    if settings.use_custom_props:
        blen_read_custom_properties(fbx_obj, ma, settings)

    return ma


# -------
# Texture

def blen_read_texture(fbx_tmpl, fbx_obj, basedir, settings):
    import os
    from bpy_extras import image_utils

    elem_name_utf8 = elem_name_ensure_class(fbx_obj, b'Texture')

    image_cache = settings.image_cache

    filepath = elem_find_first_string(fbx_obj, b'FileName')
    if os.sep == '/':
        filepath = filepath.replace('\\', '/')
    else:
        filepath = filepath.replace('/', '\\')

    image = image_cache.get(filepath)
    if image is not None:
        return image

    image = image_utils.load_image(
        filepath,
        dirname=basedir,
        place_holder=True,
        recursive=settings.use_image_search,
        )

    image_cache[filepath] = image
    # name can be ../a/b/c
    image.name = os.path.basename(elem_name_utf8)

    if settings.use_custom_props:
        blen_read_custom_properties(fbx_obj, image, settings)

    return image


def blen_read_camera(fbx_tmpl, fbx_obj, global_scale):
    # meters to inches
    M2I = 0.0393700787

    elem_name_utf8 = elem_name_ensure_class(fbx_obj, b'NodeAttribute')

    fbx_props = (elem_find_first(fbx_obj, b'Properties70'),
                 elem_find_first(fbx_tmpl, b'Properties70', fbx_elem_nil))
    assert(fbx_props[0] is not None)

    camera = bpy.data.cameras.new(name=elem_name_utf8)

    camera.type = 'ORTHO' if elem_props_get_enum(fbx_props, b'CameraProjectionType', 0) == 1 else 'PERSP'

    camera.lens = elem_props_get_number(fbx_props, b'FocalLength', 35.0)
    camera.sensor_width = elem_props_get_number(fbx_props, b'FilmWidth', 32.0 * M2I) / M2I
    camera.sensor_height = elem_props_get_number(fbx_props, b'FilmHeight', 32.0 * M2I) / M2I

    camera.ortho_scale = elem_props_get_number(fbx_props, b'OrthoZoom', 1.0)

    filmaspect = camera.sensor_width / camera.sensor_height
    # film offset
    camera.shift_x = elem_props_get_number(fbx_props, b'FilmOffsetX', 0.0) / (M2I * camera.sensor_width)
    camera.shift_y = elem_props_get_number(fbx_props, b'FilmOffsetY', 0.0) / (M2I * camera.sensor_height * filmaspect)

    camera.clip_start = elem_props_get_number(fbx_props, b'NearPlane', 0.01) * global_scale
    camera.clip_end = elem_props_get_number(fbx_props, b'FarPlane', 100.0) * global_scale

    return camera


def blen_read_light(fbx_tmpl, fbx_obj, global_scale):
    import math
    elem_name_utf8 = elem_name_ensure_class(fbx_obj, b'NodeAttribute')

    fbx_props = (elem_find_first(fbx_obj, b'Properties70'),
                 elem_find_first(fbx_tmpl, b'Properties70', fbx_elem_nil))
    # rare
    if fbx_props[0] is None:
        lamp = bpy.data.lamps.new(name=elem_name_utf8, type='POINT')
        return lamp

    light_type = {
        0: 'POINT',
        1: 'SUN',
        2: 'SPOT'}.get(elem_props_get_enum(fbx_props, b'LightType', 0), 'POINT')

    lamp = bpy.data.lamps.new(name=elem_name_utf8, type=light_type)

    if light_type == 'SPOT':
        spot_size = elem_props_get_number(fbx_props, b'OuterAngle', None)
        if spot_size is None:
            # Deprecated.
            spot_size = elem_props_get_number(fbx_props, b'Cone angle', 45.0)
        lamp.spot_size = math.radians(spot_size)

        spot_blend = elem_props_get_number(fbx_props, b'InnerAngle', None)
        if spot_blend is None:
            # Deprecated.
            spot_blend = elem_props_get_number(fbx_props, b'HotSpot', 45.0)
        lamp.spot_blend = 1.0 - (spot_blend / spot_size)

    # TODO, cycles
    lamp.color = elem_props_get_color_rgb(fbx_props, b'Color', (1.0, 1.0, 1.0))
    lamp.energy = elem_props_get_number(fbx_props, b'Intensity', 100.0) / 100.0
    lamp.distance = elem_props_get_number(fbx_props, b'DecayStart', 25.0) * global_scale
    lamp.shadow_method = ('RAY_SHADOW' if elem_props_get_bool(fbx_props, b'CastShadow', True) else 'NOSHADOW')
    lamp.shadow_color = elem_props_get_color_rgb(fbx_props, b'ShadowColor', (0.0, 0.0, 0.0))

    return lamp


# ### Import Utility class
class FbxImportHelperNode:
    """
    Temporary helper node to store a hierarchy of fbxNode objects before building
    Objects, Armatures and Bones. It tries to keep the correction data in one place so it can be applied consistently to the imported data.
    """

    __slots__ = ('_parent', 'anim_compensation_matrix', 'armature_setup', 'bind_matrix', 'bl_bone', 'bl_data', 'bl_obj', 'bone_child_matrix',
                 'children', 'clusters', 'fbx_elem', 'fbx_name', 'fbx_transform_data', 'fbx_type', 'has_bone_children', 'ignore', 'is_armature',
                 'is_bone', 'is_root', 'matrix', 'meshes', 'post_matrix', 'pre_matrix')

    def __init__(self, fbx_elem, bl_data, fbx_transform_data, is_bone):
        self.fbx_name = elem_name_ensure_class(fbx_elem, b'Model') if fbx_elem else 'Unknown'
        self.fbx_type = fbx_elem.props[2] if fbx_elem else None
        self.fbx_elem = fbx_elem
        self.bl_obj = None
        self.bl_data = bl_data
        self.bl_bone = None                     # Name of bone if this is a bone (this may be different to fbx_name if there was a name conflict in Blender!)
        self.fbx_transform_data = fbx_transform_data
        self.is_root = False
        self.is_bone = is_bone
        self.is_armature = False
        self.has_bone_children = False          # True if the hierarchy below this node contains bones, important to support mixed hierarchies.
        self.ignore = False                     # True for leaf-bones added to the end of some bone chains to set the lengths.
        self.pre_matrix = None                  # correction matrix that needs to be applied before the FBX transform
        self.bind_matrix = None                 # for bones this is the matrix used to bind to the skin
        self.matrix = blen_read_object_transform_do(fbx_transform_data) if fbx_transform_data else None
        self.post_matrix = None                 # correction matrix that needs to be applied after the FBX transform
        self.bone_child_matrix = None           # Objects attached to a bone end not the beginning, this matrix corrects for that
        self.anim_compensation_matrix = None    # a mesh moved in the hierarchy may have a different local matrix. This compensates animations for this.

        self.meshes = None                      # List of meshes influenced by this bone.
        self.clusters = []                      # Deformer Cluster nodes
        self.armature_setup = None              # mesh and armature matrix when the mesh was bound

        self._parent = None
        self.children = []

    @property
    def parent(self):
        return self._parent

    @parent.setter
    def parent(self, value):
        if self._parent is not None:
            self._parent.children.remove(self)
        self._parent = value
        if self._parent is not None:
            self._parent.children.append(self)

    def __repr__(self):
        if self.fbx_elem:
            return self.fbx_elem.props[1].decode()
        else:
            return "None"

    def print_info(self, indent=0):
        print(" " * indent + (self.fbx_name if self.fbx_name else "(Null)")
              + ("[root]" if self.is_root else "")
              + ("[ignore]" if self.ignore else "")
              + ("[armature]" if self.is_armature else "")
              + ("[bone]" if self.is_bone else "")
              + ("[HBC]" if self.has_bone_children else "")
              )
        for c in self.children:
            c.print_info(indent + 1)

    def mark_leaf_bones(self):
        if self.is_bone and len(self.children) == 1:
            child = self.children[0]
            if child.is_bone and len(child.children) == 0:
                child.ignore = True  # Ignore leaf bone at end of chain
        for child in self.children:
            child.mark_leaf_bones()

    def do_bake_transform(self, settings):
        return (settings.bake_space_transform and self.fbx_type in (b'Mesh', b'Null') and
                not self.is_armature and not self.is_bone)

    def find_correction_matrix(self, settings, parent_correction_inv=None):
        from bpy_extras.io_utils import axis_conversion
        from mathutils import Matrix, Vector

        if self.parent and (self.parent.is_root or self.parent.do_bake_transform(settings)):
            self.pre_matrix = settings.global_matrix

        if parent_correction_inv:
            self.pre_matrix = parent_correction_inv * (self.pre_matrix if self.pre_matrix else Matrix())

        correction_matrix = None

        if self.is_bone:
            if settings.automatic_bone_orientation:
                # find best orientation to align bone with
                bone_children = [child for child in self.children if child.is_bone]
                if len(bone_children) == 0:
                    # no children, inherit the correction from parent (if possible)
                    if self.parent and self.parent.is_bone:
                        correction_matrix = parent_correction_inv.inverted() if parent_correction_inv else None
                else:
                    # else find how best to rotate the bone to align the Y axis with the children
                    best_axis = (1, 0, 0)
                    if len(bone_children) == 1:
                        vec = bone_children[0].bind_matrix.to_translation()
                        best_axis = Vector((0, 0, 1 if vec[2] >= 0 else -1))
                        if abs(vec[0]) > abs(vec[1]):
                            if abs(vec[0]) > abs(vec[2]):
                                best_axis = Vector((1 if vec[0] >= 0 else -1, 0, 0))
                        elif abs(vec[1]) > abs(vec[2]):
                            best_axis = Vector((0, 1 if vec[1] >= 0 else -1, 0))
                    else:
                        # get the child directions once because they may be checked several times
                        child_locs = [loc.normalized() for loc in [bind_matrix.to_translation() for bind_matrix in [child.bind_matrix for child in bone_children]] if loc.magnitude > 0.0]

                        # I'm not sure which one I like better...
                        if False:
                            best_angle = -1.0
                            for i in range(6):
                                a = i // 2
                                s = -1 if i % 2 == 1 else 1
                                test_axis = Vector((s if a == 0 else 0, s if a == 1 else 0, s if a == 2 else 0))

                                # find max angle to children
                                max_angle = 1.0
                                for loc in child_locs:
                                    max_angle = min(max_angle, test_axis.dot(loc))

                                # is it better than the last one?
                                if best_angle < max_angle:
                                    best_angle = max_angle
                                    best_axis = test_axis
                        else:
                            best_angle = -1.0
                            for vec in child_locs:
                                test_axis = Vector((0, 0, 1 if vec[2] >= 0 else -1))
                                if abs(vec[0]) > abs(vec[1]):
                                    if abs(vec[0]) > abs(vec[2]):
                                        test_axis = Vector((1 if vec[0] >= 0 else -1, 0, 0))
                                elif abs(vec[1]) > abs(vec[2]):
                                    test_axis = Vector((0, 1 if vec[1] >= 0 else -1, 0))

                                # find max angle to children
                                max_angle = 1.0
                                for loc in child_locs:
                                    max_angle = min(max_angle, test_axis.dot(loc))

                                # is it better than the last one?
                                if best_angle < max_angle:
                                    best_angle = max_angle
                                    best_axis = test_axis

                    # convert best_axis to axis string
                    to_up = 'Z' if best_axis[2] >= 0 else '-Z'
                    if abs(best_axis[0]) > abs(best_axis[1]):
                        if abs(best_axis[0]) > abs(best_axis[2]):
                            to_up = 'X' if best_axis[0] >= 0 else '-X'
                    elif abs(best_axis[1]) > abs(best_axis[2]):
                        to_up = 'Y' if best_axis[1] >= 0 else '-Y'
                    to_forward = 'X' if to_up not in {'X', '-X'} else 'Y'

                    # Build correction matrix
                    if (to_up, to_forward) != ('Y', 'X'):
                        correction_matrix = axis_conversion(from_forward='X',
                                                            from_up='Y',
                                                            to_forward=to_forward,
                                                            to_up=to_up,
                                                            ).to_4x4()
            else:
                correction_matrix = settings.bone_correction_matrix
        else:
            # camera and light can be hard wired
            if self.fbx_type == b'Camera':
                correction_matrix = MAT_CONVERT_CAMERA
            elif self.fbx_type == b'Light':
                correction_matrix = MAT_CONVERT_LAMP

        self.post_matrix = correction_matrix

        if self.do_bake_transform(settings):
            self.post_matrix = settings.global_matrix_inv * (self.post_matrix if self.post_matrix else Matrix())

        # process children
        correction_matrix_inv = correction_matrix.inverted_safe() if correction_matrix else None
        for child in self.children:
            child.find_correction_matrix(settings, correction_matrix_inv)

    def find_armatures(self):
        needs_armature = False
        for child in self.children:
            if child.is_bone:
                needs_armature = True
                break
        if needs_armature:
            if self.fbx_type == b'Null':
                # if empty then convert into armature
                self.is_armature = True
            else:
                # otherwise insert a new node
                armature = FbxImportHelperNode(None, None, None, False)
                armature.fbx_name = "Armature"
                armature.is_armature = True

                for child in self.children[:]:
                    if child.is_bone:
                        child.parent = armature

                armature.parent = self

        for child in self.children:
            if child.is_armature:
                continue
            if child.is_bone:
                continue
            child.find_armatures()

    def find_bone_children(self):
        has_bone_children = False
        for child in self.children:
            has_bone_children |= child.find_bone_children()
        self.has_bone_children = has_bone_children
        return self.is_bone or has_bone_children

    def find_fake_bones(self, in_armature=False):
        if in_armature and not self.is_bone and self.has_bone_children:
            self.is_bone = True
            # if we are not a null node we need an intermediate node for the data
            if self.fbx_type != b'Null':
                node = FbxImportHelperNode(self.fbx_elem, self.bl_data, None, False)
                self.fbx_elem = None
                self.bl_data = None

                # transfer children
                for child in self.children:
                    if child.is_bone or child.has_bone_children:
                        continue
                    child.parent = node

                # attach to parent
                node.parent = self

        if self.is_armature:
            in_armature = True
        for child in self.children:
            child.find_fake_bones(in_armature)

    def get_world_matrix(self):
        from mathutils import Matrix

        matrix = self.parent.get_world_matrix() if self.parent else Matrix()
        if self.matrix:
            matrix = matrix * self.matrix
        return matrix

    def get_matrix(self):
        from mathutils import Matrix

        matrix = self.matrix if self.matrix else Matrix()
        if self.pre_matrix:
            matrix = self.pre_matrix * matrix
        if self.post_matrix:
            matrix = matrix * self.post_matrix
        return matrix

    def get_bind_matrix(self):
        from mathutils import Matrix

        matrix = self.bind_matrix if self.bind_matrix else Matrix()
        if self.pre_matrix:
            matrix = self.pre_matrix * matrix
        if self.post_matrix:
            matrix = matrix * self.post_matrix
        return matrix

    def make_bind_pose_local(self, parent_matrix=None):
        from mathutils import Matrix

        if parent_matrix is None:
            parent_matrix = Matrix()

        if self.bind_matrix:
            bind_matrix = parent_matrix.inverted_safe() * self.bind_matrix
        else:
            bind_matrix = self.matrix.copy() if self.matrix else None

        self.bind_matrix = bind_matrix
        if bind_matrix:
            parent_matrix = parent_matrix * bind_matrix

        for child in self.children:
            child.make_bind_pose_local(parent_matrix)

    def collect_skeleton_meshes(self, meshes):
        for _, m in self.clusters:
            meshes.update(m)
        for child in self.children:
            child.collect_skeleton_meshes(meshes)

    def collect_armature_meshes(self):
        if self.is_armature:
            armature_matrix_inv = self.get_world_matrix().inverted_safe()

            meshes = set()
            for child in self.children:
                child.collect_skeleton_meshes(meshes)
            for m in meshes:
                old_matrix = m.matrix
                m.matrix = armature_matrix_inv * m.get_world_matrix()
                m.anim_compensation_matrix = old_matrix.inverted_safe() * m.matrix
                m.parent = self
            self.meshes = meshes
        else:
            for child in self.children:
                child.collect_armature_meshes()

    def build_skeleton(self, arm, parent_matrix, parent_bone_size=1):
        from mathutils import Vector, Matrix

        # ----
        # Now, create the (edit)bone.
        bone = arm.bl_data.edit_bones.new(name=self.fbx_name)
        bone.select = True
        self.bl_obj = arm.bl_obj
        self.bl_data = arm.bl_data
        self.bl_bone = bone.name  # Could be different from the FBX name!

        # get average distance to children
        bone_size = 0.0
        bone_count = 0
        for child in self.children:
            if child.is_bone:
                bone_size += child.bind_matrix.to_translation().magnitude
                bone_count += 1
        if bone_count > 0:
            bone_size /= bone_count
        else:
            bone_size = parent_bone_size

        # So that our bone gets its final length, but still Y-aligned in armature space.
        # 0-length bones are automatically collapsed into their parent when you leave edit mode, so this enforces a minimum length
        bone_tail = Vector((0.0, 1.0, 0.0)) * max(0.01, bone_size)
        bone.tail = bone_tail

        # And rotate/move it to its final "rest pose".
        bone_matrix = parent_matrix * self.get_bind_matrix().normalized()

        bone.matrix = bone_matrix

        # correction for children attached to a bone. Fbx expects to attach to the head of a bone, while blender attaches to the tail.
        self.bone_child_matrix = Matrix.Translation(-bone_tail)

        for child in self.children:
            if child.ignore:
                continue
            if child.is_bone:
                child_bone = child.build_skeleton(arm, bone_matrix, bone_size)
                # Connection to parent.
                child_bone.parent = bone
                if similar_values_iter(bone.tail, child_bone.head):
                    child_bone.use_connect = True

        return bone

    def build_node(self, fbx_tmpl, settings):
        # create when linking since we need object data
        elem_name_utf8 = self.fbx_name

        # Object data must be created already
        self.bl_obj = obj = bpy.data.objects.new(name=elem_name_utf8, object_data=self.bl_data)

        fbx_props = (elem_find_first(self.fbx_elem, b'Properties70'),
                     elem_find_first(fbx_tmpl, b'Properties70', fbx_elem_nil))
        assert(fbx_props[0] is not None)

        # ----
        # Misc Attributes

        obj.color[0:3] = elem_props_get_color_rgb(fbx_props, b'Color', (0.8, 0.8, 0.8))
        obj.hide = not bool(elem_props_get_visibility(fbx_props, b'Visibility', 1.0))

        obj.matrix_basis = self.get_matrix()

        if settings.use_custom_props:
            blen_read_custom_properties(fbx_props[0], obj, settings)

        return obj

    def build_skeleton_children(self, fbx_tmpl, settings, scene):
        if self.is_bone:
            for child in self.children:
                if child.ignore:
                    continue
                child_obj = child.build_skeleton_children(fbx_tmpl, settings, scene)
                if child_obj:
                    child_obj.parent = self.bl_obj  # get the armature the bone belongs to
                    child_obj.parent_bone = self.bl_bone
                    child_obj.parent_type = 'BONE'

                    # Blender attaches to the end of a bone, while FBX attaches to the start. bone_child_matrix corrects for that.
                    if child.pre_matrix:
                        child.pre_matrix = self.bone_child_matrix * child.pre_matrix
                    else:
                        child.pre_matrix = self.bone_child_matrix

                    child_obj.matrix_basis = child.get_matrix()
            return None
        else:
            # child is not a bone
            obj = self.build_node(fbx_tmpl, settings)

            for child in self.children:
                if child.ignore:
                    continue
                child_obj = child.build_skeleton_children(fbx_tmpl, settings, scene)
                if child_obj:
                    child_obj.parent = obj

            # instance in scene
            obj_base = scene.objects.link(obj)
            obj_base.select = True

            return obj

    def set_pose_matrix(self, arm):
        pose_bone = arm.bl_obj.pose.bones[self.bl_bone]
        pose_bone.matrix_basis = self.get_bind_matrix().inverted_safe() * self.get_matrix()

        for child in self.children:
            if child.ignore:
                continue
            if child.is_bone:
                child.set_pose_matrix(arm)

    def merge_weights(self, combined_weights, fbx_cluster):
        indices = elem_prop_first(elem_find_first(fbx_cluster, b'Indexes', default=None), default=())
        weights = elem_prop_first(elem_find_first(fbx_cluster, b'Weights', default=None), default=())

        for index, weight in zip(indices, weights):
            w = combined_weights.get(index)
            if w is None:
                combined_weights[index] = [weight]
            else:
                w.append(weight)

    def set_bone_weights(self):
        ignored_children = [child for child in self.children if child.is_bone and child.ignore and len(child.clusters) > 0]

        if len(ignored_children) > 0:
            # If we have an ignored child bone we need to merge their weights into the current bone weights.
            # (This can happen both intentionally and accidentally when skinning a model. Either way, they
            # need to be moved into a parent bone or they cause animation glitches.)

            for fbx_cluster, meshes in self.clusters:
                combined_weights = {}
                self.merge_weights(combined_weights, fbx_cluster)

                for child in ignored_children:
                    for child_cluster, child_meshes in child.clusters:
                        if not meshes.isdisjoint(child_meshes):
                            self.merge_weights(combined_weights, child_cluster)

                # combine child weights
                indices = []
                weights = []
                for i, w in combined_weights.items():
                    indices.append(i)
                    if len(w) > 1:
                        weights.append(sum(w) / len(w))
                    else:
                        weights.append(w[0])

                add_vgroup_to_objects(indices, weights, self.bl_bone, [node.bl_obj for node in meshes])

            # clusters that drive meshes not included in a parent don't need to be merged
            all_meshes = set().union(*[meshes for _, meshes in self.clusters])
            for child in ignored_children:
                for child_cluster, child_meshes in child.clusters:
                    if all_meshes.isdisjoint(child_meshes):
                        indices = elem_prop_first(elem_find_first(child_cluster, b'Indexes', default=None), default=())
                        weights = elem_prop_first(elem_find_first(child_cluster, b'Weights', default=None), default=())
                        add_vgroup_to_objects(indices, weights, self.bl_bone, [node.bl_obj for node in child_meshes])
        else:
            # set the vertex weights on meshes
            for fbx_cluster, meshes in self.clusters:
                indices = elem_prop_first(elem_find_first(fbx_cluster, b'Indexes', default=None), default=())
                weights = elem_prop_first(elem_find_first(fbx_cluster, b'Weights', default=None), default=())
                add_vgroup_to_objects(indices, weights, self.bl_bone, [node.bl_obj for node in meshes])

        for child in self.children:
            if child.ignore:
                continue
            if child.is_bone:
                child.set_bone_weights()

    def build_hierarchy(self, fbx_tmpl, settings, scene):
        from mathutils import Matrix

        if self.is_armature:
            # create when linking since we need object data
            elem_name_utf8 = self.fbx_name

            self.bl_data = arm_data = bpy.data.armatures.new(name=elem_name_utf8)

            # Object data must be created already
            self.bl_obj = arm = bpy.data.objects.new(name=elem_name_utf8, object_data=arm_data)

            arm.matrix_basis = self.get_matrix()

            if self.fbx_elem:
                fbx_props = (elem_find_first(self.fbx_elem, b'Properties70'),
                             elem_find_first(fbx_tmpl, b'Properties70', fbx_elem_nil))
                assert(fbx_props[0] is not None)

                if settings.use_custom_props:
                    blen_read_custom_properties(fbx_props[0], arm, settings)

            # instance in scene
            obj_base = scene.objects.link(arm)
            obj_base.select = True

            # Add bones:

            # Switch to Edit mode.
            scene.objects.active = arm
            is_hidden = arm.hide
            arm.hide = False  # Can't switch to Edit mode hidden objects...
            bpy.ops.object.mode_set(mode='EDIT')

            for child in self.children:
                if child.ignore:
                    continue
                if child.is_bone:
                    child_obj = child.build_skeleton(self, Matrix())

            bpy.ops.object.mode_set(mode='OBJECT')

            arm.hide = is_hidden

            # Set pose matrix
            for child in self.children:
                if child.ignore:
                    continue
                if child.is_bone:
                    child.set_pose_matrix(self)

            # Add bone children:
            for child in self.children:
                if child.ignore:
                    continue
                child_obj = child.build_skeleton_children(fbx_tmpl, settings, scene)
                if child_obj:
                    child_obj.parent = arm

            # Add armature modifiers to the meshes
            if self.meshes:
                arm_mat_back = arm.matrix_basis.copy()
                for mesh in self.meshes:
                    (amat, mmat) = mesh.armature_setup

                    # bring global armature & mesh matrices into *Blender* global space.
                    amat = settings.global_matrix * amat
                    mmat = settings.global_matrix * mmat

                    arm.matrix_basis = amat
                    me_mat_back = mesh.bl_obj.matrix_basis.copy()
                    mesh.bl_obj.matrix_basis = mmat

                    mod = mesh.bl_obj.modifiers.new(elem_name_utf8, 'ARMATURE')
                    mod.object = arm

                    mesh.bl_obj.matrix_basis = me_mat_back
                arm.matrix_basis = arm_mat_back

            # Add bone weights to the deformers
            for child in self.children:
                if child.ignore:
                    continue
                if child.is_bone:
                    child.set_bone_weights()

            return arm
        elif self.fbx_elem:
            obj = self.build_node(fbx_tmpl, settings)

            # walk through children
            for child in self.children:
                child_obj = child.build_hierarchy(fbx_tmpl, settings, scene)
                child_obj.parent = obj

            # instance in scene
            obj_base = scene.objects.link(obj)
            obj_base.select = True

            return obj
        else:
            for child in self.children:
                child_obj = child.build_hierarchy(fbx_tmpl, settings, scene)


def is_ascii(filepath, size):
    with open(filepath, 'r', encoding="utf-8") as f:
        try:
            f.read(size)
            return True
        except UnicodeDecodeError:
            pass

    return False


def load(operator, context, filepath="",
         use_manual_orientation=False,
         axis_forward='-Z',
         axis_up='Y',
         global_scale=1.0,
         bake_space_transform=False,
         use_cycles=True,
         use_image_search=False,
         use_alpha_decals=False,
         decal_offset=0.0,
         use_custom_props=True,
         use_custom_props_enum_as_string=True,
         ignore_leaf_bones=False,
         automatic_bone_orientation=False,
         primary_bone_axis='Y',
         secondary_bone_axis='X',
         use_prepost_rot=True):

    global fbx_elem_nil
    fbx_elem_nil = FBXElem('', (), (), ())

    import os
    import time
    from bpy_extras.io_utils import axis_conversion
    from mathutils import Matrix

    from . import parse_fbx
    from .fbx_utils import RIGHT_HAND_AXES, FBX_FRAMERATES

    start_time = time.process_time()

    # detect ascii files
    if is_ascii(filepath, 24):
        operator.report({'ERROR'}, "ASCII FBX files are not supported %r" % filepath)
        return {'CANCELLED'}

    try:
        elem_root, version = parse_fbx.parse(filepath)
    except:
        import traceback
        traceback.print_exc()

        operator.report({'ERROR'}, "Couldn't open file %r" % filepath)
        return {'CANCELLED'}

    if version < 7100:
        operator.report({'ERROR'}, "Version %r unsupported, must be %r or later" % (version, 7100))
        return {'CANCELLED'}

    if bpy.ops.object.mode_set.poll():
        bpy.ops.object.mode_set(mode='OBJECT', toggle=False)

    # deselect all
    if bpy.ops.object.select_all.poll():
        bpy.ops.object.select_all(action='DESELECT')

    basedir = os.path.dirname(filepath)

    cycles_material_wrap_map = {}
    image_cache = {}
    if not use_cycles:
        texture_cache = {}

    # Tables: (FBX_byte_id -> [FBX_data, None or Blender_datablock])
    fbx_table_nodes = {}

    if use_alpha_decals:
        material_decals = set()
    else:
        material_decals = None

    scene = context.scene

    # #### Get some info from GlobalSettings.

    fbx_settings = elem_find_first(elem_root, b'GlobalSettings')
    fbx_settings_props = elem_find_first(fbx_settings, b'Properties70')
    if fbx_settings is None or fbx_settings_props is None:
        operator.report({'ERROR'}, "No 'GlobalSettings' found in file %r" % filepath)
        return {'CANCELLED'}

    # FBX default base unit seems to be the centimeter, while raw Blender Unit is equivalent to the meter...
    global_scale *= elem_props_get_number(fbx_settings_props, b'UnitScaleFactor', 100.0) / 100.0
    # Compute global matrix and scale.
    if not use_manual_orientation:
        axis_forward = (elem_props_get_integer(fbx_settings_props, b'FrontAxis', 1),
                        elem_props_get_integer(fbx_settings_props, b'FrontAxisSign', 1))
        axis_up = (elem_props_get_integer(fbx_settings_props, b'UpAxis', 2),
                   elem_props_get_integer(fbx_settings_props, b'UpAxisSign', 1))
        axis_coord = (elem_props_get_integer(fbx_settings_props, b'CoordAxis', 0),
                      elem_props_get_integer(fbx_settings_props, b'CoordAxisSign', 1))
        axis_key = (axis_up, axis_forward, axis_coord)
        axis_up, axis_forward = {v: k for k, v in RIGHT_HAND_AXES.items()}.get(axis_key, ('Z', 'Y'))
    global_matrix = (Matrix.Scale(global_scale, 4) *
                     axis_conversion(from_forward=axis_forward, from_up=axis_up).to_4x4())

    # To cancel out unwanted rotation/scale on nodes.
    global_matrix_inv = global_matrix.inverted()
    # For transforming mesh normals.
    global_matrix_inv_transposed = global_matrix_inv.transposed()

    # Compute bone correction matrix
    bone_correction_matrix = None  # None means no correction/identity
    if not automatic_bone_orientation:
        if (primary_bone_axis, secondary_bone_axis) != ('Y', 'X'):
            bone_correction_matrix = axis_conversion(from_forward='X',
                                                     from_up='Y',
                                                     to_forward=secondary_bone_axis,
                                                     to_up=primary_bone_axis,
                                                     ).to_4x4()

    # Compute framerate settings.
    custom_fps = elem_props_get_number(fbx_settings_props, b'CustomFrameRate', 25.0)
    time_mode = elem_props_get_enum(fbx_settings_props, b'TimeMode')
    real_fps = {eid: val for val, eid in FBX_FRAMERATES[1:]}.get(time_mode, custom_fps)
    if real_fps < 0.0:
        real_fps = 25.0
    scene.render.fps = round(real_fps)
    scene.render.fps_base = scene.render.fps / real_fps

    # store global settings that need to be accessed during conversion
    settings = FBXImportSettings(
        operator.report, (axis_up, axis_forward), global_matrix, global_scale,
        bake_space_transform, global_matrix_inv, global_matrix_inv_transposed,
        use_cycles, use_image_search,
        use_alpha_decals, decal_offset,
        use_custom_props, use_custom_props_enum_as_string,
        cycles_material_wrap_map, image_cache,
        ignore_leaf_bones, automatic_bone_orientation, bone_correction_matrix,
        use_prepost_rot,
    )

    # #### And now, the "real" data.

    fbx_defs = elem_find_first(elem_root, b'Definitions')  # can be None
    fbx_nodes = elem_find_first(elem_root, b'Objects')
    fbx_connections = elem_find_first(elem_root, b'Connections')

    if fbx_nodes is None:
        operator.report({'ERROR'}, "No 'Objects' found in file %r" % filepath)
        return {'CANCELLED'}
    if fbx_connections is None:
        operator.report({'ERROR'}, "No 'Connections' found in file %r" % filepath)
        return {'CANCELLED'}

    # ----
    # First load property templates