io_scene_gltf2/blender/exp/gltf2_blender_gather_skins.py

   1 # SPDX-FileCopyrightText: 2018-2021 The glTF-Blender-IO authors
   2 #
   3 # SPDX-License-Identifier: Apache-2.0
   4
   5 import mathutils
   6 from ...io.com import gltf2_io, gltf2_io_constants
   7 from ...io.exp import gltf2_io_binary_data
   8 from ...io.exp.gltf2_io_user_extensions import export_user_extensions
   9 from . import gltf2_blender_gather_accessors
  10 from . import gltf2_blender_gather_joints
  11 from .gltf2_blender_gather_tree import VExportNode
  12 from .gltf2_blender_gather_cache import cached
  13
  14 @cached
  15 def gather_skin(armature_uuid, export_settings):
  16     """
  17     Gather armatures, bones etc into a glTF2 skin object.
  18
  19     :param blender_object: the object which may contain a skin
  20     :param export_settings:
  21     :return: a glTF2 skin object
  22     """
  23
  24     if armature_uuid not in export_settings['vtree'].nodes:
  25         # User filtered objects to export, and keep the skined mesh, without keeping the armature
  26         return None
  27
  28     blender_armature_object = export_settings['vtree'].nodes[armature_uuid].blender_object
  29
  30     if not __filter_skin(blender_armature_object, export_settings):
  31         return None
  32
  33     skin = gltf2_io.Skin(
  34         extensions=__gather_extensions(blender_armature_object, export_settings),
  35         extras=__gather_extras(blender_armature_object, export_settings),
  36         inverse_bind_matrices=__gather_inverse_bind_matrices(armature_uuid, export_settings),
  37         joints=__gather_joints(armature_uuid, export_settings),
  38         name=__gather_name(blender_armature_object, export_settings),
  39         skeleton=__gather_skeleton(blender_armature_object, export_settings)
  40     )
  41
  42     # If armature is not exported, joints will be empty.
  43     # Do not construct skin in that case
  44     if len(skin.joints) == 0:
  45         return None
  46
  47     export_user_extensions('gather_skin_hook', export_settings, skin, blender_armature_object)
  48
  49     return skin
  50
  51
  52 def __filter_skin(blender_armature_object, export_settings):
  53     if not export_settings['gltf_skins']:
  54         return False
  55     if blender_armature_object.type != 'ARMATURE' or len(blender_armature_object.pose.bones) == 0:
  56         return False
  57
  58     return True
  59
  60
  61 def __gather_extensions(blender_armature_object, export_settings):
  62     return None
  63
  64
  65 def __gather_extras(blender_armature_object, export_settings):
  66     return None
  67
  68 def __gather_inverse_bind_matrices(armature_uuid, export_settings):
  69
  70     blender_armature_object = export_settings['vtree'].nodes[armature_uuid].blender_object
  71
  72     axis_basis_change = mathutils.Matrix.Identity(4)
  73     if export_settings['gltf_yup']:
  74         axis_basis_change = mathutils.Matrix(
  75             ((1.0, 0.0, 0.0, 0.0), (0.0, 0.0, 1.0, 0.0), (0.0, -1.0, 0.0, 0.0), (0.0, 0.0, 0.0, 1.0)))
  76
  77     # store matrix_world of armature in case we need to add a neutral bone
  78     export_settings['vtree'].nodes[armature_uuid].matrix_world_armature = blender_armature_object.matrix_world.copy()
  79
  80     bones_uuid = export_settings['vtree'].get_all_bones(armature_uuid)
  81     def __collect_matrices(bone):
  82         inverse_bind_matrix = (
  83             axis_basis_change @
  84             (
  85                 blender_armature_object.matrix_world @
  86                 bone.bone.matrix_local
  87             )
  88         ).inverted_safe()
  89         matrices.append(inverse_bind_matrix)
  90
  91     matrices = []
  92     for b in bones_uuid:
  93         if export_settings['vtree'].nodes[b].leaf_reference is None:
  94             __collect_matrices(blender_armature_object.pose.bones[export_settings['vtree'].nodes[b].blender_bone.name])
  95         else:
  96             inverse_bind_matrix = (
  97                 axis_basis_change @
  98                 (
  99                     blender_armature_object.matrix_world @
 100                     export_settings['vtree'].nodes[export_settings['vtree'].nodes[b].leaf_reference].matrix_world_tail
 101                 )
 102             ).inverted_safe()
 103             matrices.append(inverse_bind_matrix) # Leaf bone
 104
 105     # flatten the matrices
 106     inverse_matrices = []
 107     for matrix in matrices:
 108         for column in range(0, 4):
 109             for row in range(0, 4):
 110                 inverse_matrices.append(matrix[row][column])
 111
 112     binary_data = gltf2_io_binary_data.BinaryData.from_list(inverse_matrices, gltf2_io_constants.ComponentType.Float)
 113     return gltf2_blender_gather_accessors.gather_accessor(
 114         binary_data,
 115         gltf2_io_constants.ComponentType.Float,
 116         len(inverse_matrices) // gltf2_io_constants.DataType.num_elements(gltf2_io_constants.DataType.Mat4),
 117         None,
 118         None,
 119         gltf2_io_constants.DataType.Mat4,
 120         export_settings
 121     )
 122
 123
 124 def __gather_joints(armature_uuid, export_settings):
 125
 126     all_armature_children = export_settings['vtree'].nodes[armature_uuid].children
 127     root_bones_uuid = [c for c in all_armature_children if export_settings['vtree'].nodes[c].blender_type == VExportNode.BONE]
 128
 129     # Create bone nodes
 130     for root_bone_uuid in root_bones_uuid:
 131         gltf2_blender_gather_joints.gather_joint_vnode(root_bone_uuid, export_settings)
 132
 133     bones_uuid = export_settings['vtree'].get_all_bones(armature_uuid)
 134     joints = [export_settings['vtree'].nodes[b].node for b in bones_uuid]
 135     return joints
 136
 137
 138 def __gather_name(blender_armature_object, export_settings):
 139     return blender_armature_object.name
 140
 141
 142 def __gather_skeleton(blender_armature_object, export_settings):
 143     # In the future support the result of https://github.com/KhronosGroup/glTF/pull/1195
 144     return None