ATi's Z-Range optimization

[Secessionist]

Hello,

I believe I asked Dave Baumann about ATi's Z-Range optimization when I first joined, but he wasn't able to reply.

It's listed in the specs for the DX10.1 series of ATi's jank, but I don't know for sure what it does.

Can someone explain it to me?

 

[K.I.L.E.R]

I didn't know current video card technology uses a Z-buffer. I thought the concept of a Z-buffer died a few generations ago?

Am I missing something?

Are you talking about hierarchical-z?

 

[rpg.314]

Everybody uses Z-buffer.

Hierarchal Z is basically an optimized implementation of Z-buffer.

 

[Nick]

Maybe if the range of z-values within a tile is small, they can compress the tile to something more compact. That's the only thing I can think of going by the name of the feature alone...

 

[Nick]

A simple Google search gave me this: http://www.tomshardware.com/reviews/r600-finally-dx10-hardware-ati,1600-12.html

"Z-range optimization is a part of DX10. This means that you can narrow your Z buffer range to test a specific range, which can be beneficial for stencil shadows."

 

[MDolenc]

Are we talking about this: http://www.nvidia.com/dev_content/nvopenglspecs/GL_EXT_depth_bounds_test.txt
No, that's not part of DirectX spec.