'''OpenGL extension ARB.base_instance

This module customises the behaviour of the 
OpenGL.raw.GL.ARB.base_instance to provide a more 
Python-friendly API

Overview (from the spec)
	
	This extension allows the offset within buffer objects used for instanced
	rendering to be specified. This is congruent with the <first> parameter
	in glDrawArrays and the <basevertex> parameter in glDrawElements. When
	instanced rendering is performed (for example, through
	glDrawArraysInstanced), instanced vertex attributes whose vertex attribute
	divisors are non-zero are fetched from enabled vertex arrays per-instance
	rather than per-vertex. However, in unextended OpenGL, there is no way to
	define the offset into those arrays from which the attributes are fetched.
	This extension adds that offset in the form of a <basevertex> parameter
	to several new procedures.
	
	The <basevertex> parameter is added to the index of the array element, after
	division by the vertex attribute divisor. This allows several sets of
	instanced vertex attribute data to be stored in a single vertex array, and
	the base offset of that data to be specified for each draw. Further, this
	extension exposes the <basevertex> parameter as the final and previously
	undefined structure member of the draw-indirect data structure.

The official definition of this extension is available here:
http://www.opengl.org/registry/specs/ARB/base_instance.txt
'''
from OpenGL import platform, constant, arrays
from OpenGL import extensions, wrapper
import ctypes
from OpenGL.raw.GL import _types, _glgets
from OpenGL.raw.GL.ARB.base_instance import *
from OpenGL.raw.GL.ARB.base_instance import _EXTENSION_NAME

def glInitBaseInstanceARB():
    '''Return boolean indicating whether this extension is available'''
    from OpenGL import extensions
    return extensions.hasGLExtension( _EXTENSION_NAME )

# INPUT glDrawElementsInstancedBaseInstance.indices size not checked against count
glDrawElementsInstancedBaseInstance=wrapper.wrapper(glDrawElementsInstancedBaseInstance).setInputArraySize(
    'indices', None
)
# INPUT glDrawElementsInstancedBaseVertexBaseInstance.indices size not checked against count
glDrawElementsInstancedBaseVertexBaseInstance=wrapper.wrapper(glDrawElementsInstancedBaseVertexBaseInstance).setInputArraySize(
    'indices', None
)
### END AUTOGENERATED SECTION