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Collision...

Started by Arch Mar 18, 2003 at 7:37 AM 3 replies 400+ views

Original Post

Mar 18, 2003 at 7:37 AM

I''m making a completely software engine like Quake. I''m studying various collision techniques, but I have not found tutorials for real-time collision where the player can slide along a wall in a quake-like map... I found a solution by applying a sphere-plane collision test to ALL the polygons in the map, but this approach appear slow (especially if we have a high-poly map or a high-detailed map). Which is the best solution in this case ? This metod also allow me to buil maps with an editor like 3d Studio. Infact all I have to do is to read all the map''s polygons and do on these the collision test. Next I heard about bsp tree for the collision... where can I find a good tutorial on this ? Please help me ;-) Thanks for your patience...

JuNC

Mar 18, 2003 at 12:12 PM

The idea is to cut down the number of polygons you need to test, so the sphere-poly test isn''t really that slow (not that it is necessarily what you want). Use some sort of hierarchical structure to partition your poly-soup (e.g. octree, quadtree, BSP, Axis-Aligned-Box tree etc. etc.) then when it comes to collisions, extract a small number of potential colliders from the structure and use those for the sphere-poly test.

Quake uses a solid-leaf BSP which allows them to detect collision soley by clipping a line segment to one of several ''expanded'' collision trees. There was a paper by Stan Melax on expanded BSP tree collision which might be useful for you (do a search, I don''t have the link handy).

Arch

Mar 18, 2003 at 3:29 PM

thanks...

I hope to find something !!

crazylegs

Mar 20, 2003 at 12:38 PM

yeah, and if u search the net u can find a copy of michael abrash''s black book which is realy good either for concepts and for optimization,the book have 3 chapters didicated to bsp also in the last chapters he talks about the quake''s technologie, and how bsp is used in there.

Hope it helps

Arch

Mar 20, 2003 at 2:59 PM

Thanks crazylegs!!

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