Re: Problems with simple pyopengl program

Ahh, that did it, thank you so much! I had written a much larger program
based on a shader tutorial. I spent the last day and a half slowly paring
down the program until I got to that stub. I copied all of it to C, saw
that it worked, and finally had to ask someone...

Perhaps a very large note in the documentation would be good?

-James

On Wed, Feb 22, 2012 at 6:58 PM, Mike C. Fletcher <[email protected]>wrote:

> On 12-02-22 07:47 PM, James Gao wrote:
> > Hi everyone,
> > I'm trying to get a very very simple pass-through shader to work in
> > pyopengl. I compiled and tested a simple C program, available here:
> > http://pastebin.com/FGVxUUXH
> > This program works exactly as expected -- a red plane is drawn,
> > completely covering the screen.
> >
> > I tried to make the *exact* duplicate of this C program here:
> > http://pastebin.com/dYbbXTY1
> > This apparently does not work. Only the gray glClear color is
> > displayed, and the two triangles are never drawn.
> >
> > Any insight into why this isn't working?
>
> You need to modify the calls which are using voidp offsets to explicitly
> create GLvoidp instances, the integer 0 values are being interpreted as
> single-value arrays and the result is a useless offset:
>
>     glVertexAttribPointer( posidx, 2, GL_FLOAT, GL_FALSE, 4*2, GLvoidp(0))
>
>     # Draw the two triangles
>     glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebuf);
>     glDrawElements(
>         GL_TRIANGLES,           # mode
>         6,           # count
>         GL_UNSIGNED_SHORT,      # type
>         GLvoidp(0)                       # element array buffer offset
>     )
>
> This is a mis-feature of the wrapping in PyOpenGL allowing you to pass
> in an integer where an array is expected.
>
> HTH,
> Mike
>
> --
> ________________________________________________
>   Mike C. Fletcher
>   Designer, VR Plumber, Coder
>   http://www.vrplumber.com
>   http://blog.vrplumber.com
>
>
>
> ------------------------------------------------------------------------------
> Virtualization & Cloud Management Using Capacity Planning
> Cloud computing makes use of virtualization - but cloud computing
> also focuses on allowing computing to be delivered as a service.
> http://www.accelacomm.com/jaw/sfnl/114/51521223/
> _______________________________________________
> PyOpenGL Homepage
> http://pyopengl.sourceforge.net
> _______________________________________________
> PyOpenGL-Users mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/pyopengl-users
>

------------------------------------------------------------------------------
Virtualization & Cloud Management Using Capacity Planning
Cloud computing makes use of virtualization - but cloud computing 
also focuses on allowing computing to be delivered as a service.
http://www.accelacomm.com/jaw/sfnl/114/51521223/

_______________________________________________
PyOpenGL Homepage
http://pyopengl.sourceforge.net
_______________________________________________
PyOpenGL-Users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/pyopengl-users