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SuperVGA

Trying to design occlusion culling for static geometry.

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SuperVGA    1132
Hey guys!

I would like to take a shot at occlusion culling, now that i have my voxel octree with depth sorting, frustrum culling and fast regeneration.

I've been reading the Hansong Zhang's dissertation on Effective Occlusion Culling for the Interactive Display of Arbitrary Models, and i thought i could simplify the technique for my voxel octree:
I know the boundary of all my nodes, and have the distance to those at hand, so i can always render a perfect front to back order with no overlap guaranteed.

So i thought about disabling depth test, and render every vbo twice, to an off-screen occlusion map b, after testing occlusion map a, then drawing to my backbuffer and copy map b onto a.

The issue with testing against the occlusion map is, that i think i'd have to do it per vertex in a shader, or read back the texture before every draw call.

Do you think this would be feasible? Drawing a high-detail (or maybe one lod level) onto an occlusion map while checking every vertex against another occlusion map texture?

Or am i misunderstanding Zheng's paper?


Thanks in advance. :-)

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SuperVGA    1132
Or would it be clever to draw to the stencil buffer? I want to read from that somewhere above fragment level. Preferrably per vbo, or before the draw calls, but then i'd need it on the cpu...

Also, i realize testing vertices against single texels would produce artifacts around edges of occluders, -i'd have to use a tree to approximately solve occlusion of the entire polygon.

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