Hi, I've been porting my renderer from DX9 to DX10 and have run across some problems in my post effects system. My HDR system uses a 128 bit (I know I should migrate to the new dedicated formats, but later), render target for all scene rendering. At the end of the pipeline I tone map the 128 bit (A32G32R32B32) image to A8R8G8B8_UNORM using a pretty standard pixel shader: float4 color = tex2D(MeshTextureSampler, IN.Texture0); OUT.RGBColor.rgba = pow( 1.0f - exp( exposure * color ), gamma); The problem is that the expression (1.0f - exp (exposure * color)) just results in black pixels in Directx10. The same code works perfectly under my DX9 profile. There are also a few other post effects where my shader yields 0 as the result of the render that I'm kinda concerned about. Is there something that I have not read that I should be aware of? Any one know what I'm missing, because I'm all out of ideas... Thanks... [Edited by - sensate on May 16, 2008 3:16:11 PM]

Check your alpha values carefully on that step.

Thanks for the comment.

It turned out to be something a little more bizarre. (And shows that exp under hlsl dx9 was perhaps correcting the output value)

By changing the calculation to

1.0f - exp (-exposure * color)

I get the correct result on both dx10 and dx9.
Strange...

So, Why was the expression working on dx9 when it was clearly wrong?