-- | @addTorque r@ adds a pure torque with no associated linear force.
addTorque :: Vec3 Double -> Body -> Body
addTorque r b = b {
    bAngularForce = bAngularForce b + r
    }
addTorque :: Vec3 Double -> Body -> Body
addTorque r b = b {
    bAngularForce = bAngularForce b + r
    }
addTorque r b = b {
    bAngularForce = bAngularForce b + r
    }