Mike-
Thanks for your comprehensive response!  I've managed to figure out that I need to use the ARB extensions but that they do work (downloaded a c example program that convinced myself of this).  Now I gotta figure out whether there's an ARB-supporting computer I can demo to my instructor with, if not it doesn't look too bad to support both with a runtime switch ;)

Thanks again!
-Tim

On Sun, Nov 16, 2008 at 11:07 AM, Mike C. Fletcher <mcfletch@vrplumber.com> wrote:
Tim Bocek wrote:
Using Kubuntu Intrepid (8.10), PyOpenGL 3.0b6, proprietary nvidia
drivers (though I'm not sure what specific card is in this computer).
I am trying to get shaders to work using PyOpenGL, but calling

glCreateShader(GL_FRAGMENT_SHADER) produces the exception:

Traceback (most recent call last):
 File "./main.py", line 154, in <module>
   testShader = shader.FragmentShader("testShader.glsl")
 File "/home/rya/hw3/shader.py", line 11, in __init__
   self.__shader = glCreateShader(GL_FRAGMENT_SHADER)
 File "/usr/lib/python2.5/site-packages/PyOpenGL-3.0.0b6-py2.5.egg/OpenGL/platform/baseplatform.py",
line 280, in __call__
   self.__name__, self.__name__,
OpenGL.error.NullFunctionError: Attempt to call an undefined function
glCreateShader, check for bool(glCreateShader) before calling

Does this mean that my video card and/or opengl install does not
support shaders?  If that's not what this means, then what could be
going on?
 
The possibilities are (there are probably other ones, but these are what comes to mind immediately):

  * Your card does not support shaders
        o possible for fairly old/low-level hardware
  * Your card only supports shaders with the ARB extension
    (glCreateShaderARB)
        o common for slightly older hardware or drivers
  * Your card only supports lower-level "program" shaders (pre-GLSL)
        o common for older integrated graphics solutions
  * Your card is currently running in non-accelerated mode
        o e.g. because of a kernel mismatch versus the X driver
  * You are calling the shader creation before you have an active
    OpenGL context
        o many implementations require a valid GL context before they
          let you create shaders and the like
  * You are calling the code on a software-only context
        o e.g. because of requesting a context which can't be hardware
          accelerated

To debug these kinds of things:

  * lspci | grep nVidia | grep VGA
        o should tell you your card name, you can then google to see
          what features the card supports
  * glxinfo | grep -ir version
        o should tell you whether your drivers support GL version
          2.0.0 or greater
  * add glGetString( GL_VERSION ) and print the result in your code
        o if > 2.0.0 you should have glCreateShader available
  * add glGetString( GL_EXTENSIONS ) and print the result in your code
        o if GL_ARB_shader_objects is in the list, then you need to
          use the ARB form of the functionality
  * import OpenGL.GL.ARB.shader_objects and check for bool(
    glCreateShaderObjectARB )
        o when it's true, you can use it...
  * try different (known-to-work) code for initializing the context to
    be sure you get a shader-friendly context

HTH,
Mike

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