Is it right to use GL_ADD with the glTexEnv(gl_texture_env_mode, ) to get additive blending when texuring?
If so then why is this not mentioned in the Redbook?
Only GL_REPLACE, GL_MODULATE, GL_DECAL and GL_BLEND are mentioned as params to glTexEnv().
Is there any differance between GL_MULT and GL_MODULATE when using glTexEnv()?
GL_ADD is an extension, so you have to first test for whether it will work by checking the extension string.
Check for EXT_texture_env_add or ARB_texture_env_add. I would choose the ARB version if available, as it’s formally defined to saturate to 1, while the EXT version is not.
how exactly does multiply work? as in do the textures have to both be only values from 0-15 (so that you don’t go over 255 when multiplied)? I assume there must be a different way it works, but how?