Should actor massScale affect all aspects of simulation?

[Qriva0]

Hi!

Mass affects acceleration due to forces, since F=ma and a = F/m.

So anything that involves forces (which is pretty much everything in the simulation - except for gravity which is an acceleration) will be affected by it. This includes aerodynamics (drag and lift forces), maybe this is what you mean by “velocity applied to body”?

By this I meant that it does not matter what is the weight of the particle, if I add velocity directly, or particle already have velocity, then integration itself is not affected by mass (not talking about externalForces):

Code:

// apply external forces and gravity:
float4 vel = velocities[i] + (inverseMasses[i] * externalForces[i] + effectiveGravity) * deltaTime;

It also affects the rigidness of rods, since it scales rotational mass which is the scale of the inertia tensor. As a result, rods with smaller rotational mass are more easily bent by external forces, regardless of compliance.

This is important bit for me, however is that the case for rod itself? If every single particle had the same weight, there were no collisions at all, then would that affect rigidness? (rot. masses are weighted, so is there other thing that could affect it?)

Velocity (as a result of forces) is not independent of mass at all: if it were, a given force would always result in the same velocity regardless of the mass of the object it is applied to. This would make mass meaningless.

A spring (F=-kx) is a force so the resulting change in velocity (acceleration) must be affected by mass.

In that sense yes, as I said above I mean calculation wise, because obviously to move heavier object I need more energy.
When it comes to my spring, I use all particles with the same weight and actually drive velocity directly (assuming mass 1), but somehow it behaves differently.
But, you mentioned aerodynamics are also affected and I can't find relation here (dragCoeff is multiplied by normalized direction and it's not affected by weight):

Code:

velocities[p] += (-dragCoeff * rvNorm +

                                      // lift:
                                      liftCoeff * new float4(liftDirection.xyz,0)) *

                                      // scale
                                      attackAngle * math.min(aerodynamicFactor * invMasses[p] * deltaTime, 1000);