I have looked into glTexSubImage2D, but there is a problem with using it in the gem system. Mainly, the generation of texture coordinates. The GEM geos create their own texture coordinates, and they assume that the texture goes from 0,0 to 1,1 (with the potential to wrap). With sub image, it doesn't really change how other objects would use the texture, so there would be a whole bunch of pixels which are garbage.
In theory, I could extend out how objects deal with texture sizes, but it isn't there right now and would require some serious structural changes.
Later, Mark
============================ = mdanks@stormfront.com = Lead Programmer PS2 = http://www.danks.org/mark ============================
-----Original Message----- From: Dan Neveu [mailto:neveu@acsu.buffalo.edu] Sent: Wednesday, May 09, 2001 2:36 PM To: Mark Danks Cc: pd-list@iem.kug.ac.at Subject: RE: [PD] pix_movie
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.
-dan
-
Mark Danks