Playing with Sketch

recur1.lisp

(ql:quickload :sketch)

(in-package :sketch)

(defstruct point
  (x 0.0 :type short-float)
  (y 0.0 :type short-float))

(defparameter *pen* (make-pen :fill +black+
			      :stroke +black+
			      :weight 5))

(defun angle-vector (angle mag)
  (make-point :x (* (cos angle) mag)
	      :y (* (sin angle) mag)))

(defun point+ (a b)
  (make-point :x (+ (point-x a) (point-x b))
	      :y (+ (point-y a) (point-y b))))

(defun line-cur (start angle mag)
  (declare (short-float angle mag))
  (when (> mag 27)
    (let* ((p1x (point-x start))
	   (p1y (point-y start))
	   (dir (angle-vector angle mag))
	   (next (point+ start dir))
	   (p2x (point-x next))
	   (p2y (point-y next)))
      (line p1x p1y p2x p2y)
      (line-cur next (+ angle (/ 10 mag)) (* mag 0.99)))))

(defsketch recur1 ((time 0.0))
  (incf time 0.01)
  (with-pen *pen*
    (dotimes (i 6)
      (line-cur (make-point :x 200.0
			    :y 200.0)
		(- i (/ time 2))
		(* (+ (* (sin time) 0.6) 2.5) 15.0)))))

(make-instance 'recur1)