Re: OpenGL texturing

[Steve Baker <sjbaker1@airmail.net>]

Francesco Orsenigo wrote:
> How can i load a texture to use within OpenGL calls?
> Each demo/tutorial i see uses different functions, many of wich are not 
> native OpenGL...
OpenGL doesn't have calls for doing file I/O - it's a graphics API!

> I'd need to perform many pixel-by-pixel color transformations: is this 
> possible after the texture is loaded?
Possible - but very slow.  You could use glTexSubImage2D to download
a 1x1 'rectangle' of texels into the image...but don't try to do hundreds
of them per frame!

Better to change a large chunk of the texture and download that chunk
all at once using glTexSubImage2D.

---------------------------- Steve Baker -------------------------
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