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'''OpenGL extension ARB.vertex_buffer_object
This module customises the behaviour of the OpenGL.raw.GL.ARB.vertex_buffer_object to provide a more Python-friendly API
Overview (from the spec) This extension defines an interface that allows various types of data (especially vertex array data) to be cached in high-performance graphics memory on the server, thereby increasing the rate of data transfers. Chunks of data are encapsulated within "buffer objects", which conceptually are nothing more than arrays of bytes, just like any chunk of memory. An API is provided whereby applications can read from or write to buffers, either via the GL itself (glBufferData, glBufferSubData, glGetBufferSubData) or via a pointer to the memory. The latter technique is known as "mapping" a buffer. When an application maps a buffer, it is given a pointer to the memory. When the application finishes reading from or writing to the memory, it is required to "unmap" the buffer before it is once again permitted to use that buffer as a GL data source or sink. Mapping often allows applications to eliminate an extra data copy otherwise required to access the buffer, thereby enhancing performance. In addition, requiring that applications unmap the buffer to use it as a data source or sink ensures that certain classes of latent synchronization bugs cannot occur. Although this extension only defines hooks for buffer objects to be used with OpenGL's vertex array APIs, the API defined in this extension permits buffer objects to be used as either data sources or sinks for any GL command that takes a pointer as an argument. Normally, in the absence of this extension, a pointer passed into the GL is simply a pointer to the user's data. This extension defines a mechanism whereby this pointer is used not as a pointer to the data itself, but as an offset into a currently bound buffer object. The buffer object ID zero is reserved, and when buffer object zero is bound to a given target, the commands affected by that buffer binding behave normally. When a nonzero buffer ID is bound, then the pointer represents an offset. In the case of vertex arrays, this extension defines not merely one binding for all attributes, but a separate binding for each individual attribute. As a result, applications can source their attributes from multiple buffers. An application might, for example, have a model with constant texture coordinates and variable geometry. The texture coordinates might be retrieved from a buffer object with the usage mode "STATIC_DRAW", indicating to the GL that the application does not expect to update the contents of the buffer frequently or even at all, while the vertices might be retrieved from a buffer object with the usage mode "STREAM_DRAW", indicating that the vertices will be updated on a regular basis. In addition, a binding is defined by which applications can source index data (as used by DrawElements, DrawRangeElements, and MultiDrawElements) from a buffer object. On some platforms, this enables very large models to be rendered with no more than a few small commands to the graphics device. It is expected that a future extension will allow sourcing pixel data from and writing pixel data to a buffer object.
The official definition of this extension is available here: http://www.opengl.org/registry/specs/ARB/vertex_buffer_object.txt ''' from OpenGL import platform, constants, constant, arrays from OpenGL import extensions, wrapper from OpenGL.GL import glget import ctypes from OpenGL.raw.GL.ARB.vertex_buffer_object import * ### END AUTOGENERATED SECTION from OpenGL.lazywrapper import lazy from OpenGL.arrays import ArrayDatatype
glDeleteBuffersARB = arrays.setInputArraySizeType( glDeleteBuffersARB, None, arrays.GLuintArray, 'buffers', )
glGenBuffersARB = wrapper.wrapper( glGenBuffersARB ).setOutput( 'buffers', lambda n: (n,), 'n', )
def _sizeOfArrayInput( pyArgs, index, wrapper ): return ( arrays.ArrayDatatype.arrayByteCount( pyArgs[index] ) )
@lazy( glBufferDataARB ) def glBufferDataARB( baseOperation, target, size, data=None, usage=None ): """Copy given data into the currently bound vertex-buffer-data object target -- the symbolic constant indicating which buffer type is intended size -- if provided, the count-in-bytes of the array data -- data-pointer to be used, may be None to initialize without copying over a data-set usage -- hint to the driver as to how to set up access to the buffer Note: parameter "size" can be omitted, which makes the signature glBufferData( target, data, usage ) instead of: glBufferData( target, size, data, usage ) """ if usage is None: usage = data data = size size = None data = ArrayDatatype.asArray( data ) if size is None: size = ArrayDatatype.arrayByteCount( data ) return baseOperation( target, size, data, usage )
@lazy( glBufferSubDataARB ) def glBufferSubDataARB( baseOperation, target, offset, size, data=None ): """Copy subset of data into the currently bound vertex-buffer-data object target -- the symbolic constant indicating which buffer type is intended offset -- offset from beginning of buffer at which to copy bytes size -- the count-in-bytes of the array (if an int/long), if None, calculate size from data, if an array and data is None, use as data (i.e. the parameter can be omitted and calculated) data -- data-pointer to be used, may be None to initialize without copying over a data-set Note that if size is not an int/long it is considered to be data """ try: if size is not None: size = int( size ) except TypeError, err: if data is not None: raise TypeError( """Expect an integer size *or* a data-array, not both""" ) data = size size = None data = ArrayDatatype.asArray( data ) if size is None: size = ArrayDatatype.arrayByteCount( data ) return baseOperation( target, offset, size, data )
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