anchor.diff:  (defn (setf body-centre-of-mass) ((value (simple-array single-float (3)))
                                     (body body))
       (simple-array single-float (3))
  +  (declare (optimize (speed 3) (safety 1) (debug 1)))
     (with-foreign-array (v3 value '(:array :float 3))
       (newtonbodysetcentreofmass (%body-ptr body) v3))
     value)
  
positive.code: (defn (setf body-angular-damping) ((value (simple-array single-float (3)))
                                     (body body))
      (simple-array single-float (3))
    (with-foreign-array (v3 value '(:array :float 3))
      (newtonbodysetangulardamping (%body-ptr body) v3))
    value)
  
negative.code:                               (geometry geometry)
                                (mass single-float))
      null
    (declare (optimize (speed 3) (safety 1) (debug 1)))
    (newtonbodysetmassproperties (%body-ptr body) mass (%geometry-ptr geometry))
    nil)
  
  ;;------------------------------------------------------------
  
  (defn body-inertia-matrix4 ((body body)) (simple-array single-float (16))
    (declare (optimize (speed 3) (safety 1) (debug 1)))
    (with-foreign-object (m4 :float 16)
      (newtonbodygetinertiamatrix (%body-ptr body) m4)
      (ptr->m4 m4)))
  
  (defn body-inverse-intertia-matrix4 ((body body))
      (simple-array single-float (16))
    (declare (optimize (speed 3) (safety 1) (debug 1)))
    (with-foreign-object (m4 :float 16)
      (newtonbodygetinvinertiamatrix (%body-ptr body) m4)
      (ptr->m4 m4)))
  