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NVIDIAGameWorks / PhysX

NVIDIA PhysX SDK
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Direction dependent friction #674

Open ilyal451 opened 1 month ago

ilyal451 commented 1 month ago

Hi! How can I have a direction dependent friction in PhysX? I have a setup like this: a cylinder with grooves along its axis of rotation (like a gear) which while being put on a surface will have more friction while rotating around this axis than while sliding along it.

vreutskyy commented 1 month ago

Hi @ilyal451 It's usually called anisotropic friction, and unfortunately PhysX currently doesn't have it. You can try using contact reporting to apply some forces to achieve the desired behavior. Or if this cylinder isn't just some freely moving object but a part of a mechanism you can limit its motion with one of existing or make a custom joint. There can be different approaches depending on the final goal.

ilyal451 commented 4 weeks ago

@vreutskyy It worked, thanks a lot!

One more thing: I'm calculating the counter impulse as Basis * ( FrictionImpulse dot Basis ). Is that correct? It's just that I noticed some slowing down in the direction I didn't want to affect (which is though easy to mitigate by just applying more initial torque). The problem is that the more I scale (the friction) the more it drops, to the point that sometimes it stops moving in the desired direction completely (especially when actively slipping in the other direction). In all other respects it works as expected.

vreutskyy commented 3 weeks ago

Hi @ilyal451, sorry for the delay Yes, that was the idea, but it's hard to say what goes wrong without seeing what is actually going on :)

ilyal451 commented 3 weeks ago

@vreutskyy I'm going to make a demo soon where I'll put all the issues I've currently encountered (just haven't had enough time yet). Can you please keep me informed if you've already found and fixed anything, so that I don't do unnecessary job?

vreutskyy commented 3 weeks ago

Sure.

But you really should create all this issues in the correct repository https://github.com/NVIDIA-Omniverse/PhysX

People may think it's all about the old version of PhysX

ilyal451 commented 3 weeks ago

@vreutskyy Ah, OK. I see now. Thanks! :)