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"""Extension module support methods
This module provides the tools required to check whether
an extension is available
"""
VERSION_PREFIX = 'GL_VERSION_GL_'
CURRENT_GL_VERSION = ''
AVAILABLE_GL_EXTENSIONS = []
AVAILABLE_GLU_EXTENSIONS = []
def hasGLExtension( specifier ):
"""Given a string specifier, check for extension being available"""
global AVAILABLE_GL_EXTENSIONS, CURRENT_GL_VERSION
specifier = specifier.replace('.','_')
if specifier.startswith( VERSION_PREFIX ):
from OpenGL.GL import glGetString, GL_VERSION
if not CURRENT_GL_VERSION:
new = glGetString( GL_VERSION )
if new:
CURRENT_GL_VERSION = [
int(x) for x in new.split(' ',1)[0].split( '.' )
]
else:
return False # not yet loaded/supported
specifier = [
int(x)
for x in specifier[ len(VERSION_PREFIX):].split('_')
]
return specifier <= CURRENT_GL_VERSION
else:
from OpenGL.GL import glGetString, GL_EXTENSIONS
if not AVAILABLE_GL_EXTENSIONS:
AVAILABLE_GL_EXTENSIONS[:] = glGetString( GL_EXTENSIONS ).split()
return specifier in AVAILABLE_GL_EXTENSIONS
def hasGLUExtension( specifier ):
"""Given a string specifier, check for extension being available"""
from OpenGL.GLU import gluGetString, GLU_EXTENSIONS
if not AVAILABLE_GLU_EXTENSIONS:
AVAILABLE_GLU_EXTENSIONS[:] = gluGetString( GLU_EXTENSIONS )
return specifier.replace('.','_') in AVAILABLE_GLU_EXTENSIONS
class _Alternate( object ):
resolved = False
implementation = None
def __init__( self, name, *alternates ):
"""Initialize set of alternative implementations of the same function"""
self.__name__ = name
self._alternatives = alternates
def __nonzero__( self ):
for alternate in self._alternatives:
if alternate:
return True
return False
def __call__( self, *args, **named ):
"""Call, doing a late lookup and bind to find an implementation"""
for alternate in self._alternatives:
if alternate:
self.__class__.__call__ = alternate.__call__
return self( *args, **named )
from OpenGL import error
raise error.NullFunctionError(
"""Attempt to call an undefined alterate function (%s), check for bool(%s) before calling"""%(
', '.join([x.__name__ for x in self._alternatives]),
self.__name__,
)
)
def alternate( name, *functions ):
"""Construct a callable that functions as the first implementation found of given set of alternatives"""
return type( name, (_Alternate,), {} )( name, *functions )
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