(defun clears () (send *terminal-io* :refresh))

(defvar *dirty-old-x* 0)

(defvar *dirty-old-y* 0)

(defun moveto (x y)

(setq *dirty-old-x* x)

(setq *dirty-old-y* y))

(defun drawto (x y)

(send *terminal-io* :draw-line *dirty-old-x* *dirty-old-y* x y)

(moveto x y))

(defun bufplot (plot-list)

(let* ((number-of-lines (- (// (length plot-list) 2) 1))

(x (car plot-list))

(y (cadr plot-list))

(plot-list (rest2 plot-list)))

(moveto x y)

(do* ((i 0 (+ i 1)))

((= i number-of-lines))

(setq x (car plot-list))

(setq y (cadr plot-list))

(setq plot-list (rest2 plot-list))

(drawto x y))

number-of-lines))

(defun LIST-PLOT (list) ;plot lines from a list

"Plots lines on landscape from LIST containing: x1 y1 x2 y2 ..."

(let ((max (- (length list) 2))

(x (first list))

(y (second list)))

(moveto x y)

(do ((i 2 (+ i 2)))

((> i max))

(setq x (elt list i)

y (elt list (1+ i)))

(drawto x y))

(+ max 2)))

(defun putcursor (x y)

(send *terminal-io* :set-cursorpos x y))

(defun liss (theta-one theta-two delta-one delta-two radius number-of-iterations)

(let ((xmid 512)

(ymid 386)

(theta-one theta-one)

(theta-two theta-two)

(x 0)

(y 0)

(plot-list ()))

(do ((i 0 (+ i 1)))

((= i (+ 1 number-of-iterations)))

(setq x (round (+ (* radius (sin theta-one)) xmid)))

(setq y (round (+ (* radius (sin theta-one) (sin theta-two)) ymid)))

(setq plot-list (append plot-list (list x y)))

(setq theta-one (+ theta-one delta-one))

(setq theta-two (+ theta-two delta-two)))

(clears)

(bufplot plot-list)

(putcursor 0 0))

(list 'liss theta-one theta-two delta-one delta-two radius number-of-iterations))

(defun zig-zag-left-to-right ()

(let ((toggle-direction 1)

(x 0) (y 500)

(oldx 0) (oldy 0))

(do ((i 0 (+ i 50)))

((= i 1000))

(setq oldx x)

(setq oldy y)

(setq toggle-direction (* toggle-direction -1))

(setq x (+ 50 x))

(setq y (+ y (* 50 toggle-direction)))

(send *terminal-io* :draw-line oldx oldy x y))

(send *terminal-io* :draw-point 0 650)

))