pyopengl-users

Re: [PyOpenGL-Users] glGenBuffers on Windows XP and Intel 82855

[Mike C. F. <mcf...@vr...>]

Ontje Lünsdorf wrote:
> Hi,
>
> I'm trying to use vertex buffer object on a laptop with an intel 82855 graphic 
> chipset. GL_EXTENSIONS contains GL_ARB_vertex_buffer_object and GLView reports 
> that the glGenBuffers function should be available.
> If I try to call the function PyOpenGL will raise the a NullFunctionError. 
> However if I don't specify the buffer count PyOpenGL will complain about a 
> missing argument for that function.
> The same code runs without any problems on a machine with a nvidia card.
>
> Is this a PyOpenGL, driver bug or am I missing something?
>   
Are you calling glGenBuffersARB, or glGenBuffers ?  Your driver likely 
only provides the extension-based entry point (the one with the ARB 
suffix).  See the OpenGL/arrays/vbo.py module for some code showing use 
of the "alternate" function to make using promoted extensions easier.  
Oh, it also provides a basic VBO wrapper as an array data-type.

HTH,
Mike

-- 
________________________________________________
  Mike C. Fletcher
  Designer, VR Plumber, Coder
  http://www.vrplumber.com
  http://blog.vrplumber.com

Re: [PyOpenGL-Users] glGenBuffers on Windows XP and Intel 82855

[Ontje L. <Th...@gm...>]

Hi Mike,

Am Donnerstag 05 März 2009 15:04:54 schrieb Mike C. Fletcher:
> Are you calling glGenBuffersARB, or glGenBuffers ?  Your driver likely
> only provides the extension-based entry point (the one with the ARB
> suffix).  See the OpenGL/arrays/vbo.py module for some code showing use
> of the "alternate" function to make using promoted extensions easier.
> Oh, it also provides a basic VBO wrapper as an array data-type.
I tried both glGenBuffersARB and glGenBuffers but without success. It seems that 
glGenBuffersARB is completely not available ( bool(GL.glGenBuffersARB) raises an 
AttributeError ) while calling glGenBuffers exhibits some strange behaviour:

 - bool(GL.glGenBuffers) == False
 - calling GL.glGenBuffers() with a wrong amount of arguments throws a 
ValueError which informs about the calling signature of that method. So I 
assume PyOpenGL must have gathered that information from somewhere.
 - However: Checking the method availability with bool(GL.glGenBuffers) returns 
False and calling the method with correct arguments throws a NullFunctionError 
telling me to check for the method :)

Thanks to your suggestions I looked into the vbo.py module and used the 
vertex_buffer_object from PyOpenGL.GL.ARB directly. This module exposes the 
*ARB variants of those methods and guess what: Those work as expected! Thank 
you :D

Is the vertex_buffer_object module the preferred way of using this extension?

Thanks,
Ontje