/// <summary>
/// This requires a world target point,
/// tuning parameters, and the time step.
/// </summary>
/// <param name="body">The body.</param>
/// <param name="worldAnchor">The target.</param>
public FixedMouseJoint(Body body, Vector2 worldAnchor)
: base(body)
{
JointType = JointType.FixedMouse;
Frequency = 5.0f;
DampingRatio = 0.7f;
MaxForce = 1000 * body.Mass;
Debug.Assert(worldAnchor.IsValid());
_worldAnchor = worldAnchor;
LocalAnchorA = Transform.Divide(ref worldAnchor, ref BodyA._xf);
}