I'm looking to create "flag" textures. I'm doing this because I have a single texture, the channels of which contain three independent pieces of information which amount to a yes/no. I need to do three runs starting by looking at each, and I'd prefer not to have to look up all 128 bits each time.
The obvious thing to do is to use MRT to output "flag" textures with fewer bpp which will be quick to look up. Thus I only have to look up all 128 bits once, rather than three times.
I only need three bits.....but of course, OpenGL doesn't support textures anywhere near that small, and even 1-channel 8-bit textures aren't color-renderable.
I know the GL_RGBA internalFormat works, and GL_FLOAT_R32_NV is the same size and would also do. Is there a smaller one?
I looked at the glBitmap function, but I don't think it'll help at all....it doesn't seem directly associated with a 1-bpp texture or anything. Too bad.
Even if the stencil buffer were better-supported, I couldn't output to it in quite the way I'd like to, so that's not an option.