[ODE] Object hierarchies

[Jean-Sebastien Guay]

Quoting "Jon Watte (ODE)" <hplus-ode at mindcontrol.org>:

> You probably ned more information than the scene graph alone gives you.

Actually, since I'm reading the mesh hierarchies for a single object from a
single file, I have all that information at the time I build the "physics
objects" (trimeshes, geoms, bodies etc.). By that, I mean that in my context, I
would read a file "fairy.model" that contains separate meshes for the fairy body
and its wings, then a file called "car.model" that would contain separate meshes
for the car's body and its wheels. In the model file, there's a relative
transformation from a parent to each of its children meshes, and then when
reading a given model, I give it a transformation that will place the model in
the world (or relative to its parent, in any case).

So yes, I know which objects are composed of which meshes (I make the
distinction between objects/models and meshes, which are just the polygonal
elements that make up the objects).

> If you don't want the extra performance of compositing all static
> trimeshes into a single trimesh, you could just make four separate mesh
> instances, each of them with no body.

So the best thing would really be to combine trimeshes for static objects?
That's what I thought. I didn't want to go there, because the code base is
already pretty complex, but I guess I'll just have to do it.

> Also, for things
> that move, you don't want to use trimesh geoms, because they aren't that
> stable. For best stability, you want proxies (boxes, spheres, capsules)
> for objects with bodies, and trimeshes only for things that stay fixed.

I didn't know that. Is it mentioned somewhere in the docs? Then I'd have to once
again go through the geometry and deduce parameters for the proxy objects
(sphere radius, or whatever) so they envelop the real mesh as closely as
possible right?

Thanks a lot for your guidance. I'm running out of time for this project, so
hopefully with this information I can get it to work soon...

J-S
--
______________________________________________________
Jean-Sebastien Guay     jean-sebastien.guay at polymtl.ca
                         http://whitestar02.webhop.org