[sldev] [ATTN-LL] Physics engine status update?

Dirk Moerenhout blakar at gmail.com
Thu Sep 20 01:59:00 PDT 2007


> > In fact, I thought this was a major reason to use the prims concept: If
> > you
> > specify the shape and its characteristics instead of a mesh you can
> > generate as few or many triangles as you want (scaling with available
> > processing power) and calculate collisions much more efficiently.
>
> What happens if the sphere a dimple or has been turned into a torus?
> What happens if the sphere is cut?
> The reason for prims, was so they could send shapes that, even after some
> fiddling, might have complex meshs, as just a few parameters across the
> network. Rather than 100's of vertices, they send 20ish parameters.
> Lowering network bandwidth usuage and allowing the streaming of objects
> you see.

The physical simulation and the graphical representation do not match
at all times. If the math for the physical representation is too
complex it'll revert to using a shape that approximates what we see.
Similarly the visible representation may be less correct than the
physical one. Spheres are a good example.

In any case meshes are not useful at all for the physics engine.
Meshes are solely a way to represent the objects graphically. This is
exactly why sculpted prims have dodgy physics. There's no way to
represent it mathematically so the physical object is not at all alike
the visible object.

Dirk aka Blakar Ogre


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