[SOLVED] What is the role of PrecomputedConstraintCorrection or UncoupledConstraint…

[Wong]

In some scenes with a component FreeMotionAnimationLoop, the component PrecomputedConstraintCorrection or UncoupledConstraintCorrection will be used in that scenes.

So what is the role of PrecomputedConstraintCorrection or UncoupledConstraintCorrection? And what does the field compliace in UncoupledConstraintCorrection mean?

By the way, what do the rayleighMass and the rayleighStiffness in the component EulerImplicit mean?

[Hugo]

Dear Wong,

I’ll try to do it point by point and at my best knowledge!
The FreeMotionAnimationLoop corresponds to an AnimationLoop where:

1. the system without constraint is solved: this gives the free positions and velocities,
2. then the constraints are solved (I think using a GaussSeidel approach)
3. finally, a correction is applied to the free positions and velocities based on the contraint solving

The UncoupledConstraintCorrection is an approach for solving the constraint independently from eachother. In other words, each constraint is solved without considering the neighboring constraints which results in a diagonal constraint matrix. I think the field compliance corresponds to the value on this diagonal matrix.

Finally, rayleigh terms in the integration scheme (e.g. EulerImplicit) are terms aiming at numerical damping. This numerical damping can be computed based on the stiffness or mass matrix. See line 65 of EulerImplicitSolver.cpp with the r_M et and r_K terms.

Cheers,

Hugo

[Hugo]

I close the topic since the full doc is here for constraint correction.

Hugo

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