def dtype(self):
'''The numpy datatype used to represent this block member in a buffer.
:rtype: :py:class:`numpy.dtype`
:raises TypeError: If the block layout is not a standard layout.
'''
# Rule 1, 2 & 3
if isinstance(self.datatype, (Scalar, Vector)):
return self.datatype.machine_type
# Rule 10 could be defined separately to be consisted with packed/shared layout dtypes.
# However, all members are guaranteed to be preserved in standard formats, and this produces
# dtypes that are easier to work with
# Rule 4, 6, 8 & 10
if isinstance(self.datatype, Array):
element = self[0]
item_dtype = element.dtype
if isinstance(element.datatype, BasicType):
item_dtype = dtype({'names': [element.datatype.name], 'formats': [item_dtype],
'itemsize': self.array_stride})
return dtype((item_dtype, len(self)))
# Rules 5 & 7
if isinstance(self.datatype, Matrix):
if self.matrix_layout == MatrixLayout.column_major:
item_dim = 'column'
items, components = self.datatype.shape
elif self.matrix_layout == MatrixLayout.row_major:
item_dim = 'row'
components, items = self.datatype.shape
item_dtype = Vector.fromType(self.datatype.scalar_type, components).machine_type
item_dtype = dtype({'names': ['-'.join((self.datatype.name, item_dim))],
'formats': [item_dtype], 'itemsize': self.matrix_stride})
return dtype((item_dtype, items))
# Rule 9
if isinstance(self.datatype, Struct):
names = [c.name for c in self]
dtypes = [c.dtype for c in self]
offsets = []
offset = 0
for c in self:
offset = roundUp(offset, c.alignment)
offsets.append(offset)
offset += c.dtype.itemsize
struct_size = roundUp(offset, self.alignment)
return dtype({'names': names, 'formats': dtypes, 'offsets': offsets,
'itemsize': struct_size})
def alignment(self): '''How the block member is to be aligned. Returns :py:obj:`None` if the layout of the block containing this object is not a standardized layout. :rtype: :py:obj:`int` or :py:obj:`None` ''' if self.layout not in (BlockLayout.std140, BlockLayout.std430): return None if self.layout == BlockLayout.std140: alignment_rounding = Vector.vec4.machine_type.itemsize else: alignment_rounding = 1 # Rule 1 if isinstance(self.datatype, Scalar): return self.datatype.machine_type.itemsize # Rule 2 & 3 elif isinstance(self.datatype, Vector): item_type, (components,) = self.datatype.machine_type.subdtype if components == 3: components = 4 return item_type.itemsize * components # Rule 4, 6, 7 & 10 if isinstance(self.datatype, Array): return roundUp(self[0].alignment, alignment_rounding) # Rules 5 & 7 if isinstance(self.datatype, Matrix): if self.matrix_layout == MatrixLayout.column_major: items, components = self.datatype.shape elif self.matrix_layout == MatrixLayout.row_major: components, items = self.datatype.shape align_type = Array(Vector.fromType(self.datatype.scalar_type, components), items) return InterfaceBlockMember(self.block, self.name, align_type).alignment # Rule 9 if isinstance(self.datatype, Struct): alignment = max(c.alignment for c in self) return roundUp(alignment, alignment_rounding)
def dtype(self):
'''The memory layout of the uniform block.
:rtype: :py:class:`numpy.dtype`
:raises TypeError: If the block layout is not a standard layout.
'''
if self.layout.standardized:
offsets = []
offset = 0
for m in self:
offset = roundUp(offset, m.alignment)
offsets.append(offset)
offset += m.dtype.itemsize
names, formats = zip(*((m.name, m.dtype) for m in self))
return dtype({'names': list(names), 'formats': list(formats), 'offsets': offsets})
else:
raise TypeError("The layout for this interface block is not defined.")
def array_stride(self):
if not (isinstance(self.datatype, Array) and self.layout.standardized):
raise TypeError("Not an array with standardized layout.")
return roundUp(self[0].dtype.itemsize, self.alignment)
