[ODE] Ragdoll + Trimesh

[Aras Pranckevicius]

> Is it better to use trimesh collision or normal bsp collision for 
> the level.

ODE doesn't have a BSP collider (yet). So, if you have one (and it's able to 
give contact points/normals/depths - most don't), you may use it :)

> And to the ragdoll model.So it isn't recommended to use 
> own objects (like head,arms).But isn't the physicall simulation
> too inexact?

The physical simulation and the collision detection are two very separate 
things.

Physical simulation doesn't care about body shapes _at all_. All it does care 
is their mass properties (mass and inertia tensor), the forces affecting them 
and the constraints affecting them.

Collision detection doesn't care about all this - it's sole task is to report 
contact points and penetration vectors.

The thing that glues them in ODE is a special type of constraint - a contact 
joint. This thing basically doesn't allow (or corrects) body penetrations and 
models some friction.


Now, onto the ragdolls: the most important thing there is body skeleton - the 
limbs and the joints between them (joint limits that resemble real skeleton 
limits are very important also). The thing that worries you - if 
approximation of limb shapes by cylinders/boxes/spheres will be ok - isn't 
that important. Think of it - would you really notice if the lower arm would 
be just cylinder of equal radius along it's axis? It would collide with other 
things _a bit_ different. That's all.


Aras Pranckevicius aka NeARAZ
http://www.gim.ktu.lt/nesnausk/nearaz/