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51mon

OpenGL Z-Scissoring

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51mon    342
I red about Z-Scissoring in an article GPU Gems 2, The GeForce 6 Series GPU Architecture, I'm currently working on an app where I could find good use of it. I found info about the OpenGL EXT_depth_bounds_test is this the same thing? I'm using DirectX and I can't find any way to add this feature (just Screen Scissoring). So can I use this feature in DirectX or is there some other way I can incorporate it, can I add the OpenGL feature without porting the whole app to OpenGL?

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51mon    342
Quote:
Original post by SimmerD
No, DBT is not exposed under DirectX.


Thanks, I suspected that. So there is no way to use it in DirectX environment? What's the reason for not having it exposed, it has been around since the 5000 serie?

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51mon    342
Quote:
Original post by JasonBlochowiak
Can't you just use the HLSL clip() instruction and use world space position? Not quite as straightforward, but it should work.


That might work. But the thing with depth bounds test is that it discards before the PS so it's a bit faster I think. If I put clip on top of the PS code would I gain speed then, it's not like branching when both path are processed but one in shadow?

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Quote:
Original post by 51mon
Quote:
Original post by JasonBlochowiak
Can't you just use the HLSL clip() instruction and use world space position? Not quite as straightforward, but it should work.


That might work. But the thing with depth bounds test is that it discards before the PS so it's a bit faster I think. If I put clip on top of the PS code would I gain speed then, it's not like branching when both path are processed but one in shadow?


I doubt it would be as fast, but it should at least work. :)

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