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# Copyright (c) 2006-2008 Alex Holkner
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# $Id:$
'''Access byte arrays as arrays of vertex attributes.
Use `create_attribute` to create an attribute accessor given a simple format
string. Alternatively, the classes may be constructed directly.
Attribute format strings
========================
An attribute format string specifies the format of a vertex attribute. Format
strings are accepted by the `create_attribute` function as well as most
methods in the `pyglet.graphics` module.
Format strings have the following (BNF) syntax::
attribute ::= ( name | index 'g' 'n'? ) count type
``name`` describes the vertex attribute, and is one of the following
constants for the predefined attributes:
``c``
Vertex color
``e``
Edge flag
``f``
Fog coordinate
``n``
Normal vector
``s``
Secondary color
``t``
Texture coordinate
``v``
Vertex coordinate
You can alternatively create a generic indexed vertex attribute by
specifying its index in decimal followed by the constant ``g``. For
example, ``0g`` specifies the generic vertex attribute with index 0.
If the optional constant ``n`` is present after the ``g``, the
attribute is normalised to the range ``[0, 1]`` or ``[-1, 1]`` within
the range of the data type.
``count`` gives the number of data components in the attribute. For
example, a 3D vertex position has a count of 3. Some attributes
constrain the possible counts that can be used; for example, a normal
vector must have a count of 3.
``type`` gives the data type of each component of the attribute. The
following types can be used:
``b``
``GLbyte``
``B``
``GLubyte``
``s``
``GLshort``
``S``
``GLushort``
``i``
``GLint``
``I``
``GLuint``
``f``
``GLfloat``
``d``
``GLdouble``
Some attributes constrain the possible data types; for example,
normal vectors must use one of the signed data types. The use of
some data types, while not illegal, may have severe performance
concerns. For example, the use of ``GLdouble`` is discouraged,
and colours should be specified with ``GLubyte``.
Whitespace is prohibited within the format string.
Some examples follow:
``v3f``
3-float vertex position
``c4b``
4-byte colour
``1eb``
Edge flag
``0g3f``
3-float generic vertex attribute 0
``1gn1i``
Integer generic vertex attribute 1, normalized to [-1, 1]
``2gn4B``
4-byte generic vertex attribute 2, normalized to [0, 1] (because
the type is unsigned)
'''
__docformat__ = 'restructuredtext'
__version__ = '$Id: $'
import ctypes
import re
from pyglet.gl import *
from pyglet.graphics import vertexbuffer
_c_types = {
GL_BYTE: ctypes.c_byte,
GL_UNSIGNED_BYTE: ctypes.c_ubyte,
GL_SHORT: ctypes.c_short,
GL_UNSIGNED_SHORT: ctypes.c_ushort,
GL_INT: ctypes.c_int,
GL_UNSIGNED_INT: ctypes.c_uint,
GL_FLOAT: ctypes.c_float,
GL_DOUBLE: ctypes.c_double,
}
_gl_types = {
'b': GL_BYTE,
'B': GL_UNSIGNED_BYTE,
's': GL_SHORT,
'S': GL_UNSIGNED_SHORT,
'i': GL_INT,
'I': GL_UNSIGNED_INT,
'f': GL_FLOAT,
'd': GL_DOUBLE,
}
_attribute_format_re = re.compile(r'''
(?P<name>
[cefnstv] |
(?P<generic_index>[0-9]+) g
(?P<generic_normalized>n?))
(?P<count>[1234])
(?P<type>[bBsSiIfd])
''', re.VERBOSE)
_attribute_cache = {}
def _align(v, align):
return ((v - 1) & ~(align - 1)) + align
def interleave_attributes(attributes):
'''Interleave attribute offsets.
Adjusts the offsets and strides of the given attributes so that
they are interleaved. Alignment constraints are respected.
:Parameters:
`attributes` : sequence of `AbstractAttribute`
Attributes to interleave in-place.
'''
stride = 0
max_size = 0
for attribute in attributes:
stride = _align(stride, attribute.align)
attribute.offset = stride
stride += attribute.size
max_size = max(max_size, attribute.size)
stride = _align(stride, max_size)
for attribute in attributes:
attribute.stride = stride
def serialize_attributes(count, attributes):
'''Serialize attribute offsets.
Adjust the offsets of the given attributes so that they are
packed serially against each other for `count` vertices.
:Parameters:
`count` : int
Number of vertices.
`attributes` : sequence of `AbstractAttribute`
Attributes to serialze in-place.
'''
offset = 0
for attribute in attributes:
offset = _align(offset, attribute.align)
attribute.offset = offset
offset += count * attribute.stride
def create_attribute(format):
'''Create a vertex attribute description from aformatstring. import
The initial stride and offset of the attribute will be 0.
:Parameters:
`format` : str
Attribute format string. See the module summary for details.
:rtype: `AbstractAttribute`
'''
try:
cls, args = _attribute_cache[format]
return cls(*args)
except KeyError:
pass
match = _attribute_format_re.match(format)
assert match, 'Invalid attribute format %r' % format
count = int(match.group('count'))
gl_type = _gl_types[match.group('type')]
generic_index = match.group('generic_index')
if generic_index:
normalized = match.group('generic_normalized')
attr_class = GenericAttribute
args = int(generic_index), normalized, count, gl_type
else:
name = match.group('name')
attr_class = _attribute_classes[name]
if attr_class._fixed_count:
assert count == attr_class._fixed_count, \
'Attributes named "%s" must have count of %d' % (
name, attr_class._fixed_count)
args = (gl_type,)
else:
args = (count, gl_type)
_attribute_cache[format] = attr_class, args
return attr_class(*args)
class AbstractAttribute(object):
'''Abstract accessor for an attribute in a mapped buffer.
'''
_fixed_count = None
def __init__(self, count, gl_type):
'''Create the attribute accessor.
:Parameters:
`count` : int
Number of components in the attribute.
`gl_type` : int
OpenGL type enumerant; for example, ``GL_FLOAT``
'''
assert count in (1, 2, 3, 4), 'Component count out of range'
self.gl_type = gl_type
self.c_type = _c_types[gl_type]
self.count = count
self.align = ctypes.sizeof(self.c_type)
self.size = count * self.align
self.stride = self.size
self.offset = 0
def enable(self):
'''Enable the attribute using ``glEnableClientState``.'''
raise NotImplementedError('abstract')
def set_pointer(self, offset):
'''Setup this attribute to point to the currently bound buffer at
the given offset.
``offset`` should be based on the currently bound buffer's ``ptr``
member.
:Parameters:
`offset` : int
Pointer offset to the currently bound buffer for this
attribute.
'''
raise NotImplementedError('abstract')
def get_region(self, buffer, start, count):
'''Map a buffer region using this attribute as an accessor.
The returned region can be modified as if the buffer was a contiguous
array of this attribute (though it may actually be interleaved or
otherwise non-contiguous).
The returned region consists of a contiguous array of component
data elements. For example, if this attribute uses 3 floats per
vertex, and the `count` parameter is 4, the number of floats mapped
will be ``3 * 4 = 12``.
:Parameters:
`buffer` : `AbstractMappable`
The buffer to map.
`start` : int
Offset of the first vertex to map.
`count` : int
Number of vertices to map
:rtype: `AbstractBufferRegion`
'''
byte_start = self.stride * start
byte_size = self.stride * count
array_count = self.count * count
if self.stride == self.size:
# non-interleaved
ptr_type = ctypes.POINTER(self.c_type * array_count)
return buffer.get_region(byte_start, byte_size, ptr_type)
else:
# interleaved
byte_start += self.offset
byte_size -= self.offset
elem_stride = self.stride // ctypes.sizeof(self.c_type)
elem_offset = self.offset // ctypes.sizeof(self.c_type)
ptr_type = ctypes.POINTER(
self.c_type * (count * elem_stride - elem_offset))
region = buffer.get_region(byte_start, byte_size, ptr_type)
return vertexbuffer.IndirectArrayRegion(
region, array_count, self.count, elem_stride)
def set_region(self, buffer, start, count, data):
'''Set the data over a region of the buffer.
:Parameters:
`buffer` : AbstractMappable`
The buffer to modify.
`start` : int
Offset of the first vertex to set.
`count` : int
Number of vertices to set.
`data` : sequence
Sequence of data components.
'''
if self.stride == self.size:
# non-interleaved
byte_start = self.stride * start
byte_size = self.stride * count
array_count = self.count * count
data = (self.c_type * array_count)(*data)
buffer.set_data_region(data, byte_start, byte_size)
else:
# interleaved
region = self.get_region(buffer, start, count)
region[:] = data
class ColorAttribute(AbstractAttribute):
'''Color vertex attribute.'''
plural = 'colors'
def __init__(self, count, gl_type):
assert count in (3, 4), 'Color attributes must have count of 3 or 4'
super(ColorAttribute, self).__init__(count, gl_type)
def enable(self):
glEnableClientState(GL_COLOR_ARRAY)
def set_pointer(self, pointer):
glColorPointer(self.count, self.gl_type, self.stride,
self.offset + pointer)
class EdgeFlagAttribute(AbstractAttribute):
'''Edge flag attribute.'''
plural = 'edge_flags'
_fixed_count = 1
def __init__(self, gl_type):
assert gl_type in (GL_BYTE, GL_UNSIGNED_BYTE, GL_BOOL), \
'Edge flag attribute must have boolean type'
super(EdgeFlagAttribute, self).__init__(1, gl_type)
def enable(self):
glEnableClientState(GL_EDGE_FLAG_ARRAY)
def set_pointer(self, pointer):
glEdgeFlagPointer(self.stride, self.offset + pointer)
class FogCoordAttribute(AbstractAttribute):
'''Fog coordinate attribute.'''
plural = 'fog_coords'
def __init__(self, count, gl_type):
super(FogCoordAttribute, self).__init__(count, gl_type)
def enable(self):
glEnableClientState(GL_FOG_COORD_ARRAY)
def set_pointer(self, pointer):
glFogCoordPointer(self.count, self.gl_type, self.stride,
self.offset + pointer)
class NormalAttribute(AbstractAttribute):
'''Normal vector attribute.'''
plural = 'normals'
_fixed_count = 3
def __init__(self, gl_type):
assert gl_type in (GL_BYTE, GL_SHORT, GL_INT, GL_FLOAT, GL_DOUBLE), \
'Normal attribute must have signed type'
super(NormalAttribute, self).__init__(3, gl_type)
def enable(self):
glEnableClientState(GL_NORMAL_ARRAY)
def set_pointer(self, pointer):
glNormalPointer(self.gl_type, self.stride, self.offset + pointer)
class SecondaryColorAttribute(AbstractAttribute):
'''Secondary color attribute.'''
plural = 'secondary_colors'
_fixed_count = 3
def __init__(self, gl_type):
super(SecondaryColorAttribute, self).__init__(3, gl_type)
def enable(self):
glEnableClientState(GL_SECONDARY_COLOR_ARRAY)
def set_pointer(self, pointer):
glSecondaryColorPointer(3, self.gl_type, self.stride,
self.offset + pointer)
class TexCoordAttribute(AbstractAttribute):
'''Texture coordinate attribute.'''
plural = 'tex_coords'
def __init__(self, count, gl_type):
assert gl_type in (GL_SHORT, GL_INT, GL_INT, GL_FLOAT, GL_DOUBLE), \
'Texture coord attribute must have non-byte signed type'
super(TexCoordAttribute, self).__init__(count, gl_type)
def enable(self):
glEnableClientState(GL_TEXTURE_COORD_ARRAY)
def set_pointer(self, pointer):
glTexCoordPointer(self.count, self.gl_type, self.stride,
self.offset + pointer)
class VertexAttribute(AbstractAttribute):
'''Vertex coordinate attribute.'''
plural = 'vertices'
def __init__(self, count, gl_type):
assert count > 1, \
'Vertex attribute must have count of 2, 3 or 4'
assert gl_type in (GL_SHORT, GL_INT, GL_INT, GL_FLOAT, GL_DOUBLE), \
'Vertex attribute must have signed type larger than byte'
super(VertexAttribute, self).__init__(count, gl_type)
def enable(self):
glEnableClientState(GL_VERTEX_ARRAY)
def set_pointer(self, pointer):
glVertexPointer(self.count, self.gl_type, self.stride,
self.offset + pointer)
class GenericAttribute(AbstractAttribute):
'''Generic vertex attribute, used by shader programs.'''
def __init__(self, index, normalized, count, gl_type):
self.normalized = bool(normalized)
self.index = index
super(GenericAttribute, self).__init__(count, gl_type)
def enable(self):
glEnableVertexAttribArray(self.index)
def set_pointer(self, pointer):
glVertexAttribPointer(self.index, self.count, self.gl_type,
self.normalized, self.stride,
self.offset + pointer)
_attribute_classes = {
'c': ColorAttribute,
'e': EdgeFlagAttribute,
'f': FogCoordAttribute,
'n': NormalAttribute,
's': SecondaryColorAttribute,
't': TexCoordAttribute,
'v': VertexAttribute,
}
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