Re: [Algorithms] Terrain performance comparrisons
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From: Thatcher U. <tu...@tu...> - 2003-07-29 14:35:53
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On Jul 29, 2003 at 03:17 -0700, Pierre Terdiman wrote: > > I'm personally in the Chunked-LOD camp myself. It's flexible, > > easy-to-implement and speedy. The only problem I can foresee with > > the algorithm is that I think using a dynamic dataset (ala > > TreadMarks) may not be feasible. I haven't played around with it > > much myself, so there's not much to back that statement up with > > other than mere speculation. I think > it would be possible to use > > a dynamic dataset, but it would probably require > a rather > > heavily modified implementation of the algorithm. This is though, > > > as I said, mere speculation. > > I would be interested to hear more opinions about this > (esp. Thatcher's one, of course). I need a dynamic terrain for a > project. Time is short. I'm a bit familiar with Thatcher's chunk-LOD > implementation, but maybe not enough to imagine all required > modifications. > > It looks like it's possible since the code already performs > vertex-morphing all the time, but maybe I'm missing one or two > difficulties. Hm. If you're talking large-scale mod'ing of the terrain, I don't think I'd recommend it. (To do it "right", you would probably need to write changed data back to disk, and as-is the code uses variable-sized chunks all packed together in one file, plus the existing preprocessing is global; i.e. local variances can propagate influence arbitrarily far.) On the other hand, if you're talking localized craters and stuff like that, one approach would be to modify verts in memory, and remember where your craters are, so that when you re-load a chunk from disk, you can re-apply any vert mods. There are some problems with this as well; e.g. if you drop a bomb onto a flat area, there may not be many verts there, so the crater would look bad. I suppose you could go for a tesselation that is not adaptive to terrain curvature; something much more like geomips, and then the terrain mods are pretty straightforward. That's probably what I'd recommend. Geomorphing would be good to avoid pops. If you need to draw really big terrains, then a quadtree scheme instead of a flat tiled scheme could help, but if the terrain is not huge, that may not be necessary. -- Thatcher Ulrich http://tulrich.com |