@Override
protected Matrix33 getInvInertia(Body.State state) {
Matrix33 i = new Matrix33(new Vector3D(1.0 / radial, 1.0 / radial, 1.0 / axial));
Matrix33 rot = toPrincipalAxes.mult(state.getOrientation().getInverse()).toMatrix();
return rot.transpose().mult33(i).mult33(rot);
}
/**
* Rigid body implementation of a cylinder with an arbitrary axis of symmetry. The centre of mass
* is at the origin. Collisions are not handled.
*
* @param axis Direction of the axis of symmetry (along the length of the cylinder).
* @param radius Radius of the cylinder.
* @param length Length of the cylinder.
* @param mass Mass of the cylinder.
*/
public Cylinder(Vector3D axis, double radius, double length, double mass) {
this.mass = mass;
toPrincipalAxes = Quaternion.fromDirectionRoll(axis, new Vector3D(0, 0, 1), 0.0);
radial = (length * length + 3.0 * radius * radius) * mass / 12.0;
axial = 0.5 * mass * radius * radius;
}