One thing I noticed while coding collision geometry for OpenSimulator is as hollow is increased and prims are twisted or otherwise manipulated such that the hollow shape doesnt exactly follow the outer shape, the probability increases that the surfaces formed by the triangles that make up the hollow shape may actually protrude beyond those that make up the outer surface. I'm not sure what SL sims do under these conditions but what ODE (Open Dynamics Engine - most commonly used physics engine in OpenSimulator) is create a condition where physical objects may become trapped between the resulting surfaces. ODE uses trimesh colliders and surface normals for determining collision surfaces and if prim hollow surfaces protrude outside of prim outer surfaces, the surface normals for these surfaces point in the wrong direction. This can be alleviated by increasing prim vertex count, but for some of these prims vertex count may already be even greater than 4000 vertices. Increasing it further would use excessive memory and likely increase the cost of computing collisions dramatically. I've found that a limit of 95% maximum hollow is a good compromise between prim complexity and usability.
On Mon, Jul 11, 2011 at 7:34 PM, Wolfpup Lowenhar <wolfpu...@earthlink.net>wrote: > This is an automatically generated e-mail. To reply, visit: > http://codereview.secondlife.com/r/388/ > Review request for Viewer. > By Wolfpup Lowenhar. > Description > > As a Builder, I want to be able to create prims that are more than 95 % > hollow which will allow me to create more realistic paper sheets, flags, > fabric bits, ribbons, etc. > > Testing > > Built viewer locally and testes Viewer Phase of Acceptance Criteria. > > *Bugs: * STORM-58 <http://jira.secondlife.com/browse/STORM-58> > Diffs > > - doc/contributions.txt (d4cd5f0f33d2) > - indra/llmath/llvolume.cpp (d4cd5f0f33d2) > - indra/newview/llpanelobject.cpp (d4cd5f0f33d2) > - indra/newview/skins/default/xui/en/floater_tools.xml (d4cd5f0f33d2) > > View Diff <http://codereview.secondlife.com/r/388/diff/> > > _______________________________________________ > Policies and (un)subscribe information available here: > http://wiki.secondlife.com/wiki/OpenSource-Dev > Please read the policies before posting to keep unmoderated posting > privileges >
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