[Sidefx-houdini-list] DOP's angular velocity

Ben Schrijvers ben.schrijvers at guerrilla-games.com
Wed Sep 1 12:30:56 EDT 2010

  Hi there,

I've created a RBD path constraint to move objects along a path.
It's using a RBD Pin Constraint, RBD Angular Constraint and an Empty 
Object Dop to create the goal.
The Empty Object is inactive and animated along the path with a Point 
Position Dop.
All works fine as the object follows and orients to the path.
If the constraints are broken the object flies off using it's inherited 
But the object that flies of doesn't continue it's rotation. I noticed 
that angvel is a very low value.

So I'm animation the goal now using a Motion Dop and origin() expression.
This because I believe the Motion Dop calculates angvel.
But still this is not transfered to the constrained object like velocity 
seems to be.

I've now got a Motion Dop that overwrites angvel on the constrained 
object until it looses the constraint.
It basicly references the channels that get calculated on the Motion Dop 
that moves the goal object.
But I have to multiply the references by $TIMESTEP to get a good result.

Although it looks good now I'm not sure which values are oke.
The angvel values of my goal are $FPS higher then the ones on the 
constrained object.

And why is angvel not just inherited by default in the same way that 
velocity is?
Or am I doing something wrong??


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