(provide "tour")

(defun sphere-rand (n)
  (loop (let* ((x (- (* 2 (uniform-rand n)) 1))
               (nx2 (sum (^ x 2))))
          (if (< nx2 1) (return (/ x (sqrt nx2)))))))


(defun tour-plot (&rest args)
  (let ((p (apply #'spin-plot args)))
    (send p :add-slot 'tour-count -1)
    (send p :add-slot 'tour-trans nil)
    (defmeth p :do-idle () (send self :tour-step) (pause 2))
    (defmeth p :tour-step ()
      (when (< (slot-value 'tour-count) 0)
            (let ((vars (send self :num-variables))
                  (angle (abs (send self :angle))))
              (setf (slot-value 'tour-count) 
                    (random (floor (/ pi (* 2 angle)))))
              (setf (slot-value 'tour-trans) 
                    (make-rotation (sphere-rand vars) 
                                   (sphere-rand vars)
                                   angle))))
      (send self :apply-transformation (slot-value 'tour-trans))
      (setf (slot-value 'tour-count) (- (slot-value 'tour-count) 1)))
    (defmeth p :tour-on (&rest args) (apply #'send self :idle-on args))
    (let ((item (send graph-item-proto :new "Touring" p
                      :tour-on :tour-on :toggle t)))
      (send item :key #\T)
      (send (send p :menu) :append-items item))
    p))