[PD] pix_movie

Dan Neveu neveu at acsu.buffalo.edu
Wed May 9 23:36:28 CEST 2001

On Mon, 7 May 2001, Mark Danks wrote:

> To the list,
>   What are people's thoughts about how to handle non-power of two sized
> textures?  My primary goal is always speed, which means that I don't like to
> use automatic conversions, etc.  I would rather that the texture
> upload/whatever fail than do a silent conversion for me.  However, I know
> that this approach confuses other people who don't know about the internals
> of how the hardware needs the textures....
> Later, Mark

In OpenGL there is a call, glTexSubImage2D, which allows you to partially or
completely replace an existing texure with another (subImage). The helpful
thing here is that only the original texture needs to be power of 2. The
subImage can be of any size up to the original tex size. The main
restriction is that you would not be able to bind a non-power-of-2
sub-texture flush to the edges of a polygon, if that's what you require. There
will have to be a margin on each axis equalling:
origTexWidth - subTexWidth
origTexHeight - subTexHeight

I'm not sure if this is anything you're looking for, or if it has already
been implemented in GEM, but just thought I'd mention it since I'm currently
using it on an OpenGL/CAVE project that involves streaming webcam images
from my house to the VR lab and importing them into the virtual environment.
No, it's not yet working. I have to learn Perl script to do some 
pre-processing, first.


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