Havok Precision

Questions
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15

I’m learning too. It’s starting to make sense. Here’s a discussion of gravity vs. force that corroborates your view.

It also appears that setLinearVelocity may not be an equivalent alternative because it can’t apply to a specific point such as center of mass. So to your point, perhaps a generalized applied acceleration equivalent to gravity would be:

// can numInstances be zero?
// either way, handle it with low runtime cost
// It may be prudent to extract mass and CoM into an array of arrays to avoid repeated getMassProperties
// use remainder of gravity not handled by the engine.
// here, engine would be -0.01 so the remainder is -9.8
const num = mesh.physicsBody.numInstances;
if (num == 0) {
    var mp = mesh.physicsBody.getMassProperties();
    mesh.physicsBody.applyForce( -9.8*mp.mass, mp.centerOfMass)
} else for(var i = 0; i < num; i+=1) {
    var mp = mesh.physicsBody.getMassProperties(i);
    mesh.physicsBody.applyForce(-9.8*mp.mass, mp.centerOfMass,i)
}

Edit: if CoM is local space and force is world space, will need to convert CoM from local to world coordinates.
Edit2: updated code per first edit and use supplied instance iterate function:

mesh.physicsBody.iterateOverAllInstances((body,i) => {
    const mp = body.getMassProperties(i);
    body.applyForce(-9.8*mp.mass, body.getObjectCenterWorld(i),i)
});

Or shorten to:

mesh.physicsBody.iterateOverAllInstances((body,i) => 
    body.applyForce(-9.8*body.getMassProperties(i).mass, body.getObjectCenterWorld(i),i));

For an array of meshes:

meshArray.forEach((mesh)=>
    mesh.physicsBody.iterateOverAllInstances((body,i) => 
        body.applyForce(-9.8*body.getMassProperties(i).mass, body.getObjectCenterWorld(i),i)
    )
)