Originally posted by aapo
But I bet it isn't easy to find a situation where you really need PS2 shaders. You all have seen the HL2 benchmark screenshots, and there is a minimal difference between DX9 and DX8 - which tells us that DX8 shaders are at least almost as good as DX9. If I've understood right, the only effect that can't be done properly with DX8 in HL2 is the high dynamic range light effects, because like the name says, there needs to be high range of intensity values in the shader code, which only DX9 FP numbers can offer.
Well, we all know about NVIDIA's shannigans in that unamed 3dsomething03 benchmark
But I think the point is that NVIDIA did many optimizations for it that were
detectable, such as the discolored sky, the grainy water(when zoomed in). If they change it in such ways, we the people will eventually find out. Unless there is truth to NVIDIA faking screenshots, of course.
But in the above cases, the point is it was discovered when NVIDIA lowered precision.
Other effects that appear to be DX9 only can be found in Tomb Raider, like the now disabled glow effect(I think), and the DOF effect. Considering that developers want to use DX9 and keep it playable, that is probably why more exotic effects are not seen.