Re: [Algorithms] Colliding against polygon soup
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From: Conor S. <cs...@tp...> - 2000-12-07 13:17:03
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> At 09:46 AM 12/7/00 +0800, Conor Stokes wrote: > >OBB-Trees can apply to interiors rather well actually. Heightmaps are > >special cases anyway, and suited to quadtrees much better (they are a very > >2d collision problem.) > > I dislike the assumption that a terrain = heightmap. I'd like to use a > generalized mesh to represent a terrain region, say something like you'd > say in the old Dagoth Moor demo that shipped with the GeForce. Overhangs, > caves, etc. Well, in many cases maps like that can be treated as a heightmap + models :) Anyway, a height segmented quadtree can do a good job there. Still, there is a good reason why people like to use heightmaps :) > > So if you're building an interior with OBB-Trees, how do you do it? I > mean, not the technical stuff, I'm talking about the logical stuff -- do > you end up building it as discrete pieces (column 0, dais, stairs, rail, > etc.) or as a single monolithic mesh and there's some magic OBB-Tree > creation algorithm I'm unaware of that automatically takes a mesh and > decomposes it into sane OBBs? Well, actually, you can do either ways, or a combination of both. There are sane OBB algorithms, but I prefer objects and building the tree backwards from a set of objects. (I also went down the objects, as they could contain a reasonable amount of triangles). > I'm having a hard time visualizing this...what's an example of this? Do > you mean the case where the sphere is going into a "V" and pushing off of > one triangle forces it into the other? That is one of the cases that can happen. Another case is simply that you have two collisions occuring at once (say in a right angled corner) that both need to be taken care of. Conor Stokes |