I’m implementing a basic accumulation buffer using two FBO’s, one for rendering and the other for accumulation. The rendering FBO is normal RGBA, and the accumulation buffer is RGBA16. I’m blending (ONE, ONE) to add to the accumulation FBO.
Things work well until a channel is saturated. At that point it goes back to 0 instead of being clamped to 1 (as is defined in the spec and as happened on an AMD card I tested this code on).
I’m using a GeForce 9600 GT on Windows 7 64-bit with driver 326.80.