(bind-func cpvrotate (lambda (v1:cpVect v2:cpVect) (cpVect_val (- (* (tref v1 0) (tref v2 0)) (* (tref v1 1) (tref v2 1))) (+ (* (tref v1 0) (tref v2 1)) (* (tref v1 1) (tref v2 0))))))