;;;; Demonstration/Test of using SDL (Simple Media Layer) library
;;;; using CFFI for foreign function interfacing...
;;;; (C)2006 Frank Busse
;;;; Modifications Justin Heyes-Jones (more realtime, allows zoom in)
;;;; see COPYING for license
;;;; From "http://www.frank-buss.de/lisp/canvas.html"
(in-package #:sdl-examples)
(defvar *x0* 0.2)
(defvar *y0* 0.5)
(defvar *x1* 0.4)
(defvar *y1* 0.7)
(defvar *mandelbrot-width* 300)
(defvar *mandelbrot-height* 300)
(defvar *zoom-ratio* 0.5)
(defun clear-screen()
"clear the whole screen"
(sdl:clear-display (sdl:color)))
(defun update-mandelbrot-draw (width height sx sy sw sh x0 y0 x1 y1)
"draw mandelbrot from screen position sx,sy to the extent by sw,sh (width height)"
(declare (type single-float x0 y0 x1 y1)
(type fixnum width height sx sy sw sh)
(optimize (safety 3) (speed 1)))
(let ((surface-fp (sdl:fp sdl:*default-display*)))
(sdl-base::with-pixel (pix surface-fp)
(sdl:with-color (col (sdl:color))
(loop for y from sy below (+ sy sh) do
(loop for x from sx below (+ sx sw) do
(loop with a = (complex (float (+ (* (/ (- x1 x0) width) x) x0))
(float (+ (* (/ (- y1 y0) height) y) y0)))
for z = a then (+ (* z z) a)
while (< (abs z) 2)
for c from 60 above 0
finally (sdl-base::write-pixel pix x y
(sdl-cffi::sdl-map-rgb (sdl-base::pixel-format surface-fp)
(mod (* 13 (the fixnum c)) 256)
(mod (* 7 (the fixnum c)) 256)
(mod (* 2 (the fixnum c)) 256))))))))))
(defun mandelbrot
(&optional (width *mandelbrot-width*) (height *mandelbrot-height*) (x0 *x0*) (y0 *y0*) (x1 *x1*) (y1 *y1*))
"main program to draw navigate mandelbrot set"
(let ((cx 0) (cy 0) (step 30)
(frames-p (every-n-frames 5)))
(sdl:with-init ()
(sdl:window width height :title-caption "Mandelbrot" :icon-caption "Mandelbrot")
(setf (sdl:frame-rate) -1)
(sdl:with-events ()
(:idle ()
(if (>= cx width)
(and (setf cx 0) (incf cy step)))
(if (< cy height)
(update-mandelbrot-draw width height cx cy step step x0 y0 x1 y1))
(incf cx step)
(when (funcall frames-p)
(sdl:update-display)))
(:quit-event () t)
(:mouse-button-down-event (:x x :y y)
; set the new center point
(let* ((old-width (- x1 x0))
(old-height (- y1 y0))
(x-ratio (/ (float x) width))
(y-ratio (/ (float y) height))
(new-width (* old-width *zoom-ratio*))
(new-height (* old-height *zoom-ratio*))
(new-mid-x (+ x0 (* x-ratio old-width)))
(new-mid-y (+ y0 (* y-ratio old-height))))
(setf x0
(- new-mid-x (/ new-width 2.0)))
(setf y0
(- new-mid-y (/ new-height 2.0)))
(setf x1
(+ x0 new-width))
(setf y1
(+ y0 new-height)))
(setf cx 0)
(setf cy 0)
(clear-screen))
(:key-down-event (:key key)
(if (sdl:key= key :SDL-KEY-ESCAPE)
(sdl:push-quit-event)))
(:video-expose-event () (sdl:update-display))))))
