// apply a force at 'fromCenter' relative to center of the shape
public void ApplyTorque(Vector2f force, Vector2f fromCenter)
{
var radius = fromCenter.Magnitude();
// check if 'fromCenter' is outside of the shape.
if(radius > GetRadiusOn(fromCenter))
return;
// torque is the amount of force in the perpendicular direction
var torque = force.Cross(fromCenter);
// linear force is the amount of force in the parallel direction
var linearForce = force.Dot(fromCenter) / (radius != 0 ? radius : 1f);
// moment of inertia of the mass at this radius
var inertia = mass * radius * radius;
AngularAcceleration += -torque / (inertia != 0 ? inertia : 1);
ApplyForce(linearForce * force.Unit());
}