[Collada Physics] Motors

After reading Collada Physics specifications, I’ve understood that force_fields can be used to represent motors, since motor apply a force in some way. (Correct me if I’m wrong)

Specification also states that currently there is not predefined way to describe a technique.

So, my question is (if above is all true): “Has anyone defined their custom force fields? And if so, could you share your xml approach?”

I’m particularly interested in such motors as:
Attractor motors (provide gravitational attraction between two objects)
Geared motors (simplified automobile engines)
Servo motors (achieve a desired angle or velocity)
Spring motors
Thruster motors (provide a constant force on an object)
Velocity motors (use force to achieve desired velocity)

I’d imagine that this has already been addressed by various exporters and importers for 3dsmax, ageia, etc., as I have seen videos running various physical simulations that would require some form of force_fields. For example, some videos were showing car simulation, which would require creating some motor to drive and steer the car.

Thanks in advance.

Force fields are meant to mimic the functionality of the same name in Maya and in Softimage. I don’t know if 3DSMax has the same concept. It basically exerts a force on a rigid body, e.g. a gravity, or an attraction/repulsion field, etc. For an example, see this movie:

http://www.feelingsoftware.com/Files/Ni … nField.avi

Regarding motors… I’m only familiar with the PhysX joint motors. In PhysX, the rigid constraints (called joints) have parameters that can be used to drive a position (linear or angular) or velocity (linear or angular). Therefore this could be stored in a rigid constraint-specific <extra> or <technique>. We haven’t attempted to standardize these features in COLLADA yet.

I hope this helps a bit.