calculateMassInfo method
Calculate the mass information of the shape.
Implementation
@override
void calculateMassInfo(MassInfo out ){
/// I guess you could calculate box mass and split it
/// in half for the tetra...
aabb.setFromPoints(verts);
List<double> p = aabb.elements;
double x = p[3] - p[0];
double y = p[4] - p[1];
double z = p[5] - p[2];
double mass = x * y * z * density;
double divid = 1/12;
out.mass = mass;
out.inertia.set(
mass * ( 2*y*2*y + 2*z*2*z ) * divid, 0, 0,
0, mass * ( 2*x*2*x + 2*z*2*z ) * divid, 0,
0, 0, mass * ( 2*y*2*y + 2*x*2*x ) * divid
);
}