RE: [Algorithms] Colliding against polygon soup

[Andrew F. <An...@cl...>]

8= From: Brian Hook [mailto:bw...@wk...]
8= I dislike the assumption that a terrain = heightmap.

me too:)

8= So if you're building an interior with OBB-Trees, how do you 
8= do it?  I 
8= mean, not the technical stuff, I'm talking about the logical 
8= stuff -- do 
8= you end up building it as discrete pieces (column 0, dais, 
8= stairs, rail, 
8= etc.) or as a single monolithic mesh and there's some magic OBB-Tree 
8= creation algorithm I'm unaware of that automatically takes a 
8= mesh and 
8= decomposes it into sane OBBs?

i think your normal obbtreeing algo is fairly good with strange meshes
[owing to the arbitrary orientation allowed on the bv]. however i think it's
fairly common to have a different spatial partitioning system used for the
larger areas [kdtree, hgrid, quad/octree, etc.], and then you only tree up
cells in your spatial partition anyway. So if you have an appropriate
partitioning system for the nature of your world, you may well find that
within each cell the landscape is fairly well-behaved, even if the entire
world/area is complex.

so my answer to the question would be that you get a single monolithic mesh
from the artists, and generate your own discrete pieces.

hth,

Andy