Collision response implementation

[galoko]

Hello! First of all - thank you for your work, it's an excellent real-time FEM simulation. There is only one thing I want to ask about and it is about collision response. In your 2D FEM implementation you use fairly simple direct clamping of particle position, however, when I tried this approach for this simulation it seem to cause a lot of artifacts. So the question is, how to implement proper collision response? Maybe you can point me to some parts of PBD code that do something similuar?

[galoko]

	//velocity update
	for (int i = nFixedVertices; i < nVerts; i++) {
		v[i] = (x[i] - x_old[i]) / dt;
	}

        //floor constraint (added by me)
	for (int i = nFixedVertices; i < nVerts; i++) {
		if (x[i].y() < -0.2) {
			v[i].y() = 0.0f;
		}
	}

this does not work at all :(