View Full Version : blending

09-10-2000, 08:00 PM
I am somewhat new to openGL programming (and 3d graphics in general), and I was wondering if there was a way to use a particuler RGB value to denote a translucent area, as one can do with DirectDraw, or can one only use Alpha values?
why I wish to do this is because it would allow highly irreguler edges without the need to make many little surfaces, simply by giving the areas of the texture that are to translucant, say, an RGB value of (255,255,255), which can be done with any paint program, rather then setting the alpha values, which would have to be done from within the program itself.....
hope yea can help me on this...

09-11-2000, 02:14 AM

I think you mean color keying. You should look at http://nate.scuzzy.net/gltut/ for some tutorials on color keying, billboarding and transparency through an alpha channel.

Hope this helps,

Daniel Palomo van Es

09-13-2000, 07:40 AM
that is how I ended up doing it; I was just curious if there was a standard function to perform the same task.
it might be more speed efficient to create a small filter program that you feed in a .RAW file in RGB format (from, say, paint shop pro), and it creates a file in RGBA format, for later use by ones application.
this would remove the need to perform all those operations everytime the image is loaded.

09-14-2000, 04:29 PM
All major image editors include transparency support. Load your textures from TGA files and all is well.

You can find TGA loading code in NeHe's tutorial section.

09-15-2000, 09:55 AM
obviously something to look into, thanks=)