[PyOpenGL-Users] glVertexAttribPointer(); loading platform-specific functions

[Joshua D. <joshuardavis@q.com>]

I have some questions that probably boil down to my inexperience with  
Python. My setup is PyOpenGL-3.0.0c1 on Python 2.5.x on Mac OS X. I'm  
trying to modernize my OpenGL to use VBOs and vertex attributes,  
working through the tutorials at http://bazaar.launchpad.net/ 
~mcfletch/openglcontext/trunk/annotate/head:/tests/shader_4.py. When  
I execute code like this:

vertexBufferObject = vbo.VBO(...)
gl.glVertexAttribPointer(positionLocation, 3, GL_FLOAT, False, 24,  
vertexBufferObject)

The second line generates this error:

ctypes.ArgumentError: argument 6: <type 'exceptions.TypeError'>:  
Don't know how to convert parameter 6

The following code is what I've been doing to get platform-specific  
(?) PyOpenGL functions. They often seem to require some massaging of  
argument types; is the same thing needed for glVertexAttribPointer()  
above?

# This is adapted from http://www.pygame.org/wiki/GLSLExample.
try:
     from OpenGL import platform
     gl = platform.OpenGL
except ImportError:
     try:
         gl = cdll.LoadLibrary('libGL.so')
     except OSError:
         from ctypes.util import find_library
         path = find_library('OpenGL')
         gl = cdll.LoadLibrary(path)
gl.glShaderSource.argtypes = [c_int, c_int, POINTER(c_char_p), POINTER 
(c_int)]
gl.glGetShaderiv.argtypes = [c_int, c_int, POINTER(c_int)]
gl.glGetShaderInfoLog.argtypes = [c_int, c_int, POINTER(c_int),  
c_char_p]

Is there some newer, better way to load these functions? Is there  
some web tutorial that explains what's going on here, so that I can  
debug it myself next time?

Thanks -- Josh