Z buffer Depth...

[Appledrop]

hi there, i noticed the zbuffer field in my graphic card control panel, the options are :-
16
16,24
16,24;8bit stencil
16,24,32
16,24,32;8 bit stencil

it was set at 16, which i assume is default.. I decided to test what it did (albeit a very lame test 😛 ), and loaded atitool, the spinning cube, and waited for my average to level out, (it leveled out about 480 fps), and then i changed the zbuffer from 16 bit, to 16,24,32;8 bit stencil, expecting either a loss or a gain of performance, but the fps was about exactly the same...

if anyone can tell me what it does, and what the optimal setting should be, i'd be greatful 🙂

Thanks

 

[Appledrop]

bump :<

 

[Appledrop]

wow. second bump :S guess nobody knows ?

 

[kylebisme]

It's a long story, check google.

 

[Matthias99]

Well, it probably would make zero difference in a really simple test like that. The Z-buffer is used for sorting 3D surfaces that overlap, so that (in theory) the GPU doesn't have to waste time drawing triangles that are not visible because they are behind other objects. Stencil buffers are used for certain shader operations (such as the real-time lights in Doom3, which use stencil shadowing).

It *sounds* like this is an option to set the depth or precision of the Z-buffer. It's hard to say what effect this might have on performance -- higher-precision buffers might slow things down in simple scenes, but could help out more in complex ones. What you would need to test it is something that does 'overdraw' testing, where they specifically draw lots of objects in front of one another to see how good the occlusion algorithms are. I believe one of AquaMark3's tests does this. You could also try benching Doom3, since it uses stencil shadows, and see if it makes any difference.