Contact modification behavior


I have to model my own tank behavior with contact modifications by setting velocity of each contact.
When I use Convex Geometries to realise that behavior strange things happen :

  • when my object is aligned with the world frame it does not rotate has expected.
  • when it is 45° misaligned the behavior is correct.

Is that a bug or an incorrect physx calculation ???

Here are the 2 pictures of the setup.

I use physx 3.4.2 on linux.


It’s not clear from the diagrams what the problem is. Would it be possible to provide a PVD capture of good and bad behaviour and information about the target velocities you are applying on each contact?

I’m not able to build a PVD capture of my software, neither by Socket transport nor File transport (my getScenePvdClient() pointer remains NULL…)

for the problem : I set target velocities aligned with the vehicle, for the left caterpillar I set it directed behind and for the right caterpillar directed to the front (with a vector length of 1 m/s).
therefore it will apply a “torque” to the vehicle and make it turn on itself.

But… it works when the tank is not aligned on an axis (any one, X, Y or Z !).
The closer it gets to an axis alignment the slower the rotation is and it even stops when it reach the alignement…

I’ve got a step time of 1ms if it can help…

I’ll try to make a video instead but I need to remove some confidential aspects first or build another bench test.