Re: [PyOpenGL-Users] Textures usage

[Frédéric <fre...@gb...>]

On vendredi 08 janvier 2010, Gijs wrote:

> > Ok, I will first try glCopyTexImage2D. From where should I call it?
> > Should it be in a GL-specific context? What if the image ratio change?
> > How do I handle this? Can I resize the texture?
> 
> Well, depends on your implementation where you'd want to put the 
> glCopyTex command, but probably somewhere after or before the drawing 
> function.

My goal is to make a slideshow program. So, new images are loaded according 
to the timeline... But I presume that I can't use opengl functions outside 
initializeGL(), resizeGL() or paintGL() methods, in my callback binded to 
that timeline?

> If you want to draw a texture that has dimensions of 512x512 
> on a 640x480 screen, OpenGL just resizes the texture accordingly. The 
> final image might look a bit crushed or stretched, depending on the 
> resolution that you draw at and the original resolution of your
>  texture,  so you might need something like mipmapping to fix this. But
>  try it without mipmapping first.

My question was more about the ratio; as you can see in the code, I compute 
the mapping of the texture from the image size. But then, if I want to load 
a new image with a different ratio, how do I expand/shrink the previous 
one?

-- 
    Frédéric

    http://www.gbiloba.org