ok new thread - the old one was getting stale because the title no longer properly described the question.
How can you set up opengl to use the alpha from one texture (or the color of that texture as an alpha) - To render another texture with?
eg. texture 1: sprite image, 8 bit paletted with the paletted_texture extension.
texture 2: sprite alpha, 8 bit paletted with the paletted_texture extension, but using only greys (yes this must be paletted and not simply greyscale)
now I want to use texture 2 as the alpha for texture 1. how?
*** I am using palettes because of the effects that can be done with them, so I don't want to hear that I should be using rgba please ***
Thanks in advance for your help, and taking the time to read this sortof long post.