pyopengl-users

Re: [PyOpenGL-Users] second call to glGenFramebuffersEXT() crashes

[Joshua R. D. <jd...@ca...>]

----- Original Message -----
From: "Mike C. Fletcher" <mcf...@vr...>
To: "Joshua R. Davis" <jd...@ca...>
Cc: pyo...@li...
Sent: Saturday, February 14, 2009 5:10:59 PM GMT -06:00 US/Canada Central
Subject: Re: [PyOpenGL-Users] second call to glGenFramebuffersEXT() crashes

Joshua R. Davis wrote:
> > I am trying to cast shadows from multiple lights using shaders. I use one framebuffer object per light. When I have just one light, it works. When I try two lights, the program survives the first call to glGenFramebuffersEXT() but crashes ("Bus error") upon the second call to it.

[snip]

> If you can run the script above instead of directly accessing the 
functions from the DLL we may be able to track down the problem further.

Thanks a lot, Mike. I no longer crash when making multiple calls to glGenFramebuffersEXT(). However, I now crash on the first call to glBindFramebufferEXT(). This demo...

#! /usr/bin/env python
from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GLUT import *
from OpenGL.GL.EXT.framebuffer_object import *
def main():
    glutInit(0)
    glutInitDisplayMode(GLUT_RGB|GLUT_DOUBLE|GLUT_DEPTH)
    glutCreateWindow('test')
    framebuffer = glGenFramebuffersEXT(1)
    print framebuffer
    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, framebuffer)
if __name__ == "__main__":
    main()

...produces this error:

> python fbotest.py
1
Traceback (most recent call last):
  File "fbotest.py", line 14, in <module>
    main()
  File "fbotest.py", line 12, in main
    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, framebuffer)
  File "/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/site-packages/PyOpenGL-3.0.0b6-py2.5.egg/OpenGL/platform/baseplatform.py", line 275, in __call__
    return self( *args, **named )
ctypes.ArgumentError: argument 2: <type 'exceptions.TypeError'>: wrong type

This kind of code used to work, when I was using the DLL. Can anyone help?

Joshua Davis

Re: [PyOpenGL-Users] second call to glGenFramebuffersEXT() crashes

[Joshua R. D. <jd...@ca...>]

Mike C. Fletcher" <mcf...@vr...> wrote:
> I'm able to run that code with my AMD64 Ubuntu machine using numpy 1.1.1 
> on Python 2.5.2 .  Can you print the *type* of framebuffer.  My guess is 
> that it's a numpy uint object (it is on my machine) and that for some 
> reason on your machine that type isn't getting properly registered as a 
> uint-compatible type (possibly a 64-bit versus 32-bit issue, maybe a 
> numpy version issue, or maybe numpy isn't on your machine and you're 
> getting something else entirely).

The type of framebuffer is <type 'numpy.uint32'>. But it appears that some combination of updating PyOpenGL to 3.0.0c1 and updating Python to 2.5.4 has fixed everything; no more problems. That'll teach me to use old versions. Thanks for your help.

Joshua Davis

Re: [PyOpenGL-Users] second call to glGenFramebuffersEXT() crashes

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

Joshua R. Davis wrote:
> ----- Original Message -----
> From: "Mike C. Fletcher" <mcf...@vr...>
> To: "Joshua R. Davis" <jd...@ca...>
> Cc: pyo...@li...
> Sent: Saturday, February 14, 2009 5:10:59 PM GMT -06:00 US/Canada Central
> Subject: Re: [PyOpenGL-Users] second call to glGenFramebuffersEXT() crashes
>   
...
> Thanks a lot, Mike. I no longer crash when making multiple calls to glGenFramebuffersEXT(). However, I now crash on the first call to glBindFramebufferEXT(). This demo...
>   
...
>> python fbotest.py
>>     
> 1
> Traceback (most recent call last):
>   File "fbotest.py", line 14, in <module>
>     main()
>   File "fbotest.py", line 12, in main
>     glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, framebuffer)
>   File "/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/site-packages/PyOpenGL-3.0.0b6-py2.5.egg/OpenGL/platform/baseplatform.py", line 275, in __call__
>     return self( *args, **named )
> ctypes.ArgumentError: argument 2: <type 'exceptions.TypeError'>: wrong type
>
> This kind of code used to work, when I was using the DLL. Can anyone help?
>   
I'm able to run that code with my AMD64 Ubuntu machine using numpy 1.1.1 
on Python 2.5.2 .  Can you print the *type* of framebuffer.  My guess is 
that it's a numpy uint object (it is on my machine) and that for some 
reason on your machine that type isn't getting properly registered as a 
uint-compatible type (possibly a 64-bit versus 32-bit issue, maybe a 
numpy version issue, or maybe numpy isn't on your machine and you're 
getting something else entirely).

Thanks for the report, hopefully we can track down what's gone wrong here,
Mike

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