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jpventoso

UltraShadow on ATI?

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Hello everybody, Yesterday I implemented Hardware Shadow Mapping (taking advantage of the nVidia's UltraShadow technology) on my 3D engine. Luckily it was easier than I expected :) I tested on my GeForce 6800 and it ran ok. But today I decided to try it on an ATI 2400+, hoping that the engine would automatically switch to standard Shadow Mapping (I use CheckDeviceFormat), and for my surprise, the engine started with Hardware Shadow Mapping enabled! So I went into debug mode, and I found that the ATI device allowed the use of a DEPTHSTENCIL usage texture with D24S8 format. Plus, I found that the intrinsic tex2Dproj returned the depth comparison as nVidia does! Is this normal? I thought that UltraShadow technology was a patent of nVidia. Did somebody have the same experience? Thanks in advance!

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UltraShadow technology is for accelerating stencil shadow volumes, not shadow maps. The NVIDIA shadow map feature you are most likely referring to is PCF (Percentage Closer Filtering). PCF is implemented in several ATI cards, for example in the 2400+ card that you have.

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Oh, thanks for the answer, my mistake then... That's good news! So I ended up implementing a feature that goes beyond nVidia, without knowing that!
Well, thanks again! You made my day :)

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