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Silly_con

Why Spatial partitioning if frustrum culling ?

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Silly_con    136
why is necesary spatial partitioning like bsp, octree... if you implement a frustrum culling? all out the frustrum is culled, only what you see is what you render (frustrum + backface culling)

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ToohrVyk    1595
Without a partitioning system, you need to check each polygon against the frustum individually, which means for 10,000 polygons, you will have 10,000 tests to cull 7,500 of them.

With a partitioning system, you will check "boxes" (the leaves and/or nodes of your partitioning system) against the frustum, eliminating all polygons in those boxes if they are not visible(for instance, the first plane in a BSP might eliminate 5,000 polygons in only one test). And in a perfect case you''d be getting around 2-3 tests to cull 7,500 polygons and then another 40-50 tests to check the remaining polygons are visible (again, by boxes).

And 50 tests definitely beats 10,000.

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