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# SPDX-License-Identifier: Apache-2.0
# Copyright 2018-2021 The glTF-Blender-IO authors.
import struct
import numpy as np
from ..com.gltf2_io import Accessor
from ..com.gltf2_io_constants import ComponentType, DataType
class BinaryData():
"""Binary reader."""
def __new__(cls, *args, **kwargs):
raise RuntimeError("%s should not be instantiated" % cls)
# Note that this function is not used in Blender importer, but is kept in
# Source code to be used in any pipeline that want to manage gltf/glb file in python
@staticmethod
def get_binary_from_accessor(gltf, accessor_idx):
"""Get binary from accessor."""
accessor = gltf.data.accessors[accessor_idx]
if accessor.buffer_view is None:
return None
data = BinaryData.get_buffer_view(gltf, accessor.buffer_view)
accessor_offset = accessor.byte_offset
if accessor_offset is None:
accessor_offset = 0
return data[accessor_offset:]
@staticmethod
def get_buffer_view(gltf, buffer_view_idx):
"""Get binary data for buffer view."""
buffer_view = gltf.data.buffer_views[buffer_view_idx]
if buffer_view.buffer in gltf.buffers.keys():
buffer = gltf.buffers[buffer_view.buffer]
else:
# load buffer
gltf.load_buffer(buffer_view.buffer)
buffer = gltf.buffers[buffer_view.buffer]
byte_offset = buffer_view.byte_offset
if byte_offset is None:
byte_offset = 0
return buffer[byte_offset:byte_offset + buffer_view.byte_length]
@staticmethod
def get_data_from_accessor(gltf, accessor_idx, cache=False):
"""Get data from accessor."""
if accessor_idx in gltf.accessor_cache:
return gltf.accessor_cache[accessor_idx]
data = BinaryData.decode_accessor(gltf, accessor_idx).tolist()
if cache:
gltf.accessor_cache[accessor_idx] = data
return data
@staticmethod
def decode_accessor(gltf, accessor_idx, cache=False):
"""Decodes accessor to 2D numpy array (count x num_components)."""
if accessor_idx in gltf.decode_accessor_cache:
return gltf.accessor_cache[accessor_idx]
accessor = gltf.data.accessors[accessor_idx]
array = BinaryData.decode_accessor_obj(gltf, accessor)
if cache:
gltf.accessor_cache[accessor_idx] = array
# Prevent accidentally modifying cached arrays
array.flags.writeable = False
return array
@staticmethod
def decode_accessor_internal(accessor):
# Is use internally when accessor binary data is not yet in a glTF buffer_view
# MAT2/3 have special alignment requirements that aren't handled. But it
# doesn't matter because nothing uses them.
assert accessor.type not in ['MAT2', 'MAT3']
dtype = ComponentType.to_numpy_dtype(accessor.component_type)
component_nb = DataType.num_elements(accessor.type)
buffer_data = accessor.buffer_view.data
accessor_offset = accessor.byte_offset or 0
buffer_data = buffer_data[accessor_offset:]
bytes_per_elem = dtype(1).nbytes
default_stride = bytes_per_elem * component_nb
stride = default_stride
array = np.frombuffer(
buffer_data,
dtype=np.dtype(dtype).newbyteorder('<'),
count=accessor.count * component_nb,
)
array = array.reshape(accessor.count, component_nb)
return array
@staticmethod
def decode_accessor_obj(gltf, accessor):
# MAT2/3 have special alignment requirements that aren't handled. But it
# doesn't matter because nothing uses them.
assert accessor.type not in ['MAT2', 'MAT3']
dtype = ComponentType.to_numpy_dtype(accessor.component_type)
component_nb = DataType.num_elements(accessor.type)
if accessor.buffer_view is not None:
bufferView = gltf.data.buffer_views[accessor.buffer_view]
buffer_data = BinaryData.get_buffer_view(gltf, accessor.buffer_view)
accessor_offset = accessor.byte_offset or 0
buffer_data = buffer_data[accessor_offset:]
bytes_per_elem = dtype(1).nbytes
default_stride = bytes_per_elem * component_nb
stride = bufferView.byte_stride or default_stride
if stride == default_stride:
array = np.frombuffer(
buffer_data,
dtype=np.dtype(dtype).newbyteorder('<'),
count=accessor.count * component_nb,
)
array = array.reshape(accessor.count, component_nb)
else:
# The data looks like
# XXXppXXXppXXXppXXX
# where X are the components and p are padding.
# One XXXpp group is one stride's worth of data.
assert stride % bytes_per_elem == 0
elems_per_stride = stride // bytes_per_elem
num_elems = (accessor.count - 1) * elems_per_stride + component_nb
array = np.frombuffer(
buffer_data,
dtype=np.dtype(dtype).newbyteorder('<'),
count=num_elems,
)
assert array.strides[0] == bytes_per_elem
array = np.lib.stride_tricks.as_strided(
array,
shape=(accessor.count, component_nb),
strides=(stride, bytes_per_elem),
)
else:
# No buffer view; initialize to zeros
array = np.zeros((accessor.count, component_nb), dtype=dtype)
if accessor.sparse:
sparse_indices_obj = Accessor.from_dict({
'count': accessor.sparse.count,
'bufferView': accessor.sparse.indices.buffer_view,
'byteOffset': accessor.sparse.indices.byte_offset or 0,
'componentType': accessor.sparse.indices.component_type,
'type': 'SCALAR',
})
sparse_indices = BinaryData.decode_accessor_obj(gltf, sparse_indices_obj)
sparse_indices = sparse_indices.reshape(len(sparse_indices))
sparse_values_obj = Accessor.from_dict({
'count': accessor.sparse.count,
'bufferView': accessor.sparse.values.buffer_view,
'byteOffset': accessor.sparse.values.byte_offset or 0,
'componentType': accessor.component_type,
'type': accessor.type,
})
sparse_values = BinaryData.decode_accessor_obj(gltf, sparse_values_obj)
if not array.flags.writeable:
array = array.copy()
array[sparse_indices] = sparse_values
# Normalization
if accessor.normalized:
if accessor.component_type == 5120: # int8
array = np.maximum(-1.0, array / 127.0)
elif accessor.component_type == 5121: # uint8
array = array / 255.0
elif accessor.component_type == 5122: # int16
array = np.maximum(-1.0, array / 32767.0)
elif accessor.component_type == 5123: # uint16
array = array / 65535.0
array = array.astype(np.float32, copy=False)
return array
@staticmethod
def get_image_data(gltf, img_idx):
"""Get data from image."""
pyimage = gltf.data.images[img_idx]
assert not (
pyimage.uri is not None and
pyimage.buffer_view is not None
)
if pyimage.uri is not None:
return gltf.load_uri(pyimage.uri)
if pyimage.buffer_view is not None:
return BinaryData.get_buffer_view(gltf, pyimage.buffer_view)
return None
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