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# SPDX-License-Identifier: Apache-2.0
# Copyright 2018-2021 The glTF-Blender-IO authors.
from ctypes import *
from io_scene_gltf2.io.com.gltf2_io import BufferView
from io_scene_gltf2.io.imp.gltf2_io_binary import BinaryData
from ...io.com.gltf2_io_debug import print_console
from io_scene_gltf2.io.com.gltf2_io_draco_compression_extension import dll_path
def decode_primitive(gltf, prim):
"""
Handles draco compression.
Moves decoded data into new buffers and buffer views held by the accessors of the given primitive.
"""
# Load DLL and setup function signatures.
dll = cdll.LoadLibrary(str(dll_path().resolve()))
dll.decoderCreate.restype = c_void_p
dll.decoderCreate.argtypes = []
dll.decoderRelease.restype = None
dll.decoderRelease.argtypes = [c_void_p]
dll.decoderDecode.restype = c_bool
dll.decoderDecode.argtypes = [c_void_p, c_void_p, c_size_t]
dll.decoderReadAttribute.restype = c_bool
dll.decoderReadAttribute.argtypes = [c_void_p, c_uint32, c_size_t, c_char_p]
dll.decoderGetVertexCount.restype = c_uint32
dll.decoderGetVertexCount.argtypes = [c_void_p]
dll.decoderGetIndexCount.restype = c_uint32
dll.decoderGetIndexCount.argtypes = [c_void_p]
dll.decoderAttributeIsNormalized.restype = c_bool
dll.decoderAttributeIsNormalized.argtypes = [c_void_p, c_uint32]
dll.decoderGetAttributeByteLength.restype = c_size_t
dll.decoderGetAttributeByteLength.argtypes = [c_void_p, c_uint32]
dll.decoderCopyAttribute.restype = None
dll.decoderCopyAttribute.argtypes = [c_void_p, c_uint32, c_void_p]
dll.decoderReadIndices.restype = c_bool
dll.decoderReadIndices.argtypes = [c_void_p, c_size_t]
dll.decoderGetIndicesByteLength.restype = c_size_t
dll.decoderGetIndicesByteLength.argtypes = [c_void_p]
dll.decoderCopyIndices.restype = None
dll.decoderCopyIndices.argtypes = [c_void_p, c_void_p]
decoder = dll.decoderCreate()
extension = prim.extensions['KHR_draco_mesh_compression']
name = prim.name if hasattr(prim, 'name') else '[unnamed]'
# Create Draco decoder.
draco_buffer = bytes(BinaryData.get_buffer_view(gltf, extension['bufferView']))
if not dll.decoderDecode(decoder, draco_buffer, len(draco_buffer)):
print_console('ERROR', 'Draco Decoder: Unable to decode. Skipping primitive {}.'.format(name))
return
# Choose a buffer index which does not yet exist, skipping over existing glTF buffers yet to be loaded
# and buffers which were generated and did not exist in the initial glTF file, like this decoder does.
base_buffer_idx = len(gltf.data.buffers)
for existing_buffer_idx in gltf.buffers:
if base_buffer_idx <= existing_buffer_idx:
base_buffer_idx = existing_buffer_idx + 1
# Read indices.
index_accessor = gltf.data.accessors[prim.indices]
if dll.decoderGetIndexCount(decoder) != index_accessor.count:
print_console('WARNING', 'Draco Decoder: Index count of accessor and decoded index count does not match. Updating accessor.')
index_accessor.count = dll.decoderGetIndexCount(decoder)
if not dll.decoderReadIndices(decoder, index_accessor.component_type):
print_console('ERROR', 'Draco Decoder: Unable to decode indices. Skipping primitive {}.'.format(name))
return
indices_byte_length = dll.decoderGetIndicesByteLength(decoder)
decoded_data = bytes(indices_byte_length)
dll.decoderCopyIndices(decoder, decoded_data)
# Generate a new buffer holding the decoded indices.
gltf.buffers[base_buffer_idx] = decoded_data
# Create a buffer view referencing the new buffer.
gltf.data.buffer_views.append(BufferView.from_dict({
'buffer': base_buffer_idx,
'byteLength': indices_byte_length
}))
# Update accessor to point to the new buffer view.
index_accessor.buffer_view = len(gltf.data.buffer_views) - 1
# Read each attribute.
for attr_idx, attr in enumerate(extension['attributes']):
dracoId = extension['attributes'][attr]
if attr not in prim.attributes:
print_console('ERROR', 'Draco Decoder: Draco attribute {} not in primitive attributes. Skipping primitive {}.'.format(attr, name))
return
accessor = gltf.data.accessors[prim.attributes[attr]]
if dll.decoderGetVertexCount(decoder) != accessor.count:
print_console('WARNING', 'Draco Decoder: Vertex count of accessor and decoded vertex count does not match for attribute {}. Updating accessor.'.format(attr, name))
accessor.count = dll.decoderGetVertexCount(decoder)
if not dll.decoderReadAttribute(decoder, dracoId, accessor.component_type, accessor.type.encode()):
print_console('ERROR', 'Draco Decoder: Could not decode attribute {}. Skipping primitive {}.'.format(attr, name))
return
byte_length = dll.decoderGetAttributeByteLength(decoder, dracoId)
decoded_data = bytes(byte_length)
dll.decoderCopyAttribute(decoder, dracoId, decoded_data)
# Generate a new buffer holding the decoded vertex data.
buffer_idx = base_buffer_idx + 1 + attr_idx
gltf.buffers[buffer_idx] = decoded_data
# Create a buffer view referencing the new buffer.
gltf.data.buffer_views.append(BufferView.from_dict({
'buffer': buffer_idx,
'byteLength': byte_length
}))
# Update accessor to point to the new buffer view.
accessor.buffer_view = len(gltf.data.buffer_views) - 1
dll.decoderRelease(decoder)
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