Originally posted by PH:
Use the alpha channel as suggested and, for your particular case, use the alpha test instead of blending.
Alpha testing shouldn’t be used extensively in modern programs, the main reason being that it breaks multisampled antialiasing.
Funny you should mention that - I’ve just recently been looking at that and yes, alpha tested polygons don’t get any antialiasing. Perhaps the GL_SAMPLE_ALPHA_TO_COVERAGE_ARB is of some use but I haven’t really looked too much at the details regarding multisampling.