Originally posted by davepermen:
[b]rgpc, normally you need higher precicion depthmaps for shadows than only 8bit, so you use several of the components of the cubemap to store the depthvalues…
theoretically, we could use one simple texture with GL_LUMINANCE and GL_FLOAT32 format… but no, vendors messed that up
so we have to encode the float32 into rgba32 and decode it back to float32. happily, this is a quick code, 1 instruction decode, one instruction encode if i remember right. bad is, its lossy. it looses the exponent and only stores the mantissa actually… hm… could be done different… hehe but thats more costy.[/b]
Actually, you can use R32f texture, or even a R16f works fine. It’s exposed in DX at least, and nothing in the interface prevents you from doing the same in OpenGL, though I’m not sure the driver supports that yet.