io_scene_gltf2/blender/imp/gltf2_io_draco_compression_extension.py

   1 # SPDX-FileCopyrightText: 2018-2021 The glTF-Blender-IO authors
   2 #
   3 # SPDX-License-Identifier: Apache-2.0
   4
   5 from ctypes import *
   6
   7 from ...io.com.gltf2_io import BufferView
   8 from ...io.imp.gltf2_io_binary import BinaryData
   9 from ...io.com.gltf2_io_draco_compression_extension import dll_path
  10
  11
  12 def decode_primitive(gltf, prim):
  13     """
  14     Handles draco compression.
  15     Moves decoded data into new buffers and buffer views held by the accessors of the given primitive.
  16     """
  17
  18     # Load DLL and setup function signatures.
  19     dll = cdll.LoadLibrary(str(dll_path().resolve()))
  20
  21     dll.decoderCreate.restype = c_void_p
  22     dll.decoderCreate.argtypes = []
  23
  24     dll.decoderRelease.restype = None
  25     dll.decoderRelease.argtypes = [c_void_p]
  26
  27     dll.decoderDecode.restype = c_bool
  28     dll.decoderDecode.argtypes = [c_void_p, c_void_p, c_size_t]
  29
  30     dll.decoderReadAttribute.restype = c_bool
  31     dll.decoderReadAttribute.argtypes = [c_void_p, c_uint32, c_size_t, c_char_p]
  32
  33     dll.decoderGetVertexCount.restype = c_uint32
  34     dll.decoderGetVertexCount.argtypes = [c_void_p]
  35
  36     dll.decoderGetIndexCount.restype = c_uint32
  37     dll.decoderGetIndexCount.argtypes = [c_void_p]
  38
  39     dll.decoderAttributeIsNormalized.restype = c_bool
  40     dll.decoderAttributeIsNormalized.argtypes = [c_void_p, c_uint32]
  41
  42     dll.decoderGetAttributeByteLength.restype = c_size_t
  43     dll.decoderGetAttributeByteLength.argtypes = [c_void_p, c_uint32]
  44
  45     dll.decoderCopyAttribute.restype = None
  46     dll.decoderCopyAttribute.argtypes = [c_void_p, c_uint32, c_void_p]
  47
  48     dll.decoderReadIndices.restype = c_bool
  49     dll.decoderReadIndices.argtypes = [c_void_p, c_size_t]
  50
  51     dll.decoderGetIndicesByteLength.restype = c_size_t
  52     dll.decoderGetIndicesByteLength.argtypes = [c_void_p]
  53
  54     dll.decoderCopyIndices.restype = None
  55     dll.decoderCopyIndices.argtypes = [c_void_p, c_void_p]
  56
  57     decoder = dll.decoderCreate()
  58     extension = prim.extensions['KHR_draco_mesh_compression']
  59
  60     name = prim.name if hasattr(prim, 'name') else '[unnamed]'
  61
  62     # Create Draco decoder.
  63     draco_buffer = bytes(BinaryData.get_buffer_view(gltf, extension['bufferView']))
  64     if not dll.decoderDecode(decoder, draco_buffer, len(draco_buffer)):
  65         gltf.log.error('Draco Decoder: Unable to decode. Skipping primitive {}.'.format(name))
  66         return
  67
  68     # Choose a buffer index which does not yet exist, skipping over existing glTF buffers yet to be loaded
  69     # and buffers which were generated and did not exist in the initial glTF file, like this decoder does.
  70     base_buffer_idx = len(gltf.data.buffers)
  71     for existing_buffer_idx in gltf.buffers:
  72         if base_buffer_idx <= existing_buffer_idx:
  73             base_buffer_idx = existing_buffer_idx + 1
  74
  75     # Read indices.
  76     index_accessor = gltf.data.accessors[prim.indices]
  77     if dll.decoderGetIndexCount(decoder) != index_accessor.count:
  78         gltf.log.warning('Draco Decoder: Index count of accessor and decoded index count does not match. Updating accessor.')
  79         index_accessor.count = dll.decoderGetIndexCount(decoder)
  80     if not dll.decoderReadIndices(decoder, index_accessor.component_type):
  81         gltf.log.error('Draco Decoder: Unable to decode indices. Skipping primitive {}.'.format(name))
  82         return
  83
  84     indices_byte_length = dll.decoderGetIndicesByteLength(decoder)
  85     decoded_data = bytes(indices_byte_length)
  86     dll.decoderCopyIndices(decoder, decoded_data)
  87
  88     # Generate a new buffer holding the decoded indices.
  89     gltf.buffers[base_buffer_idx] = decoded_data
  90
  91     # Create a buffer view referencing the new buffer.
  92     gltf.data.buffer_views.append(BufferView.from_dict({
  93         'buffer': base_buffer_idx,
  94         'byteLength': indices_byte_length
  95     }))
  96
  97     # Update accessor to point to the new buffer view.
  98     index_accessor.buffer_view = len(gltf.data.buffer_views) - 1
  99
 100     # Read each attribute.
 101     for attr_idx, attr in enumerate(extension['attributes']):
 102         dracoId = extension['attributes'][attr]
 103         if attr not in prim.attributes:
 104             gltf.log.error('Draco Decoder: Draco attribute {} not in primitive attributes. Skipping primitive {}.'.format(attr, name))
 105             return
 106
 107         accessor = gltf.data.accessors[prim.attributes[attr]]
 108         if dll.decoderGetVertexCount(decoder) != accessor.count:
 109             gltf.log.warning('Draco Decoder: Vertex count of accessor and decoded vertex count does not match for attribute {}. Updating accessor.'.format(attr, name))
 110             accessor.count = dll.decoderGetVertexCount(decoder)
 111         if not dll.decoderReadAttribute(decoder, dracoId, accessor.component_type, accessor.type.encode()):
 112             gltf.log.error('Draco Decoder: Could not decode attribute {}. Skipping primitive {}.'.format(attr, name))
 113             return
 114
 115         byte_length = dll.decoderGetAttributeByteLength(decoder, dracoId)
 116         decoded_data = bytes(byte_length)
 117         dll.decoderCopyAttribute(decoder, dracoId, decoded_data)
 118
 119         # Generate a new buffer holding the decoded vertex data.
 120         buffer_idx = base_buffer_idx + 1 + attr_idx
 121         gltf.buffers[buffer_idx] = decoded_data
 122
 123         # Create a buffer view referencing the new buffer.
 124         gltf.data.buffer_views.append(BufferView.from_dict({
 125             'buffer': buffer_idx,
 126             'byteLength': byte_length
 127         }))
 128
 129         # Update accessor to point to the new buffer view.
 130         accessor.buffer_view = len(gltf.data.buffer_views) - 1
 131
 132     dll.decoderRelease(decoder)