Long story short is that I’d like to store 8 four bit values in a 32 bit attachment and decode them in a shader. Am I totally screwed without requiring shader model 4? Int samplers and bit masks/shifts are the straight forward way of doing this, but is there another way of which I am too tired to think?
Alfonse, I cannot as I also need a RGBA8 attachment, and yes I was indeed referring to texture attatchments to a framebuffer object, sorry for not being clear. I am in essence trying to shove more useful data into 1 attachment to get around the limitation of needing to have the same formats bound to all color attachments.
It basically sounds like the same thing I am doing: stuffing 3 8 bit lightmap values into a 32 bit float. Except you have one more to store. Should work though, by the law of conservation of bits