Adding Verlet Integration & Tuning Deformation Constraints

Adding Verlet Integration

Using the Verlet Integration scheme, the cloth appears alot bouncier for some reason. If i increase the global damping constant i can achieve more realistic results. This means having a damping factor for Euler and damping factor for Verlet, which is not ideal.

I spotted a mistake in the constraint code. I was actually over-shooting the displacement of the spring-ends. It was this that was causing the instability. Now euler actually works ok with constraints.

However, the best looking results i am getting with Verlet.

The act of constraining appears to dampen the system. meaning damping factors have to be lowered if constraining is on. This makes sense since we are basically taking energy out of the springs when we stop them deforming too much.


Tuning Deformation Constraints

While constraining is now fixed and more stable, it causes the cloth to wibble when the constraints are fully satisfied. Constraints are continually being invalidated by other constraints. It will not sit still! At 10% satisfaction the wibbling is hardly there but the cloth is still too rubbery and bouncey.

So the more realistic i make the cloth (i.e the more i up the stiffness), the more it wibbles!

After further inspection, it seems i can increase the stiffness by increasing the number of constrain passes, only satisfying by 10% per pass, WITHOUT increasing the wibbling. However, the simulation becomes pretty slow in debug with 3 or more passes. Release will do around 20 passes without looking too slow, and the cloth looks very nice and stiff.