Clothes penetrate each other using PhysX SDK 3.3.1


I am using PhysX to model behaviors of clothes.

I create two pieces of cloth, and add a collision plane.

I also enable self collision by PxCloth::setSelfCollisionDistance() and PxCloth::setSelfCollisionStiffness().

And then, I enable cloth inter-collision by PxScene::setInterCollisionDistance() and PxScene::setInterCollisionStiffness().

The result of setting PxScene::setInterCollisionDistance(0.1)
As you can see, the clothes penetrate each other.

But if I set PxScene::setInterCollisionDistance(0.5)
The cloth looks good during simulation.

Does anyone know why the collision distance 0.1 is not work in my case?

Thanks in advanced!