REBOL [ Title: "Mandelbrot" Date: 21-Sep-2001 Version: 0.0.1 File: %mandelbrot.r Author: "Keith Ray" Purpose: "Create Mandelbrot Set " Email: %keithray--yahoo--com library: [ level: none platform: none type: none domain: [GUI math] tested-under: none support: none license: none see-also: none ] ] clear-im: func [im [image!] color [tuple!]][ repeat j im/size/x * im/size/y [poke im j color] ] set-pixel: func [ im [image!] x [integer!] y [integer!] color [tuple!] /local x-siz y-siz siz ][ x-siz: im/size/x y-siz: im/size/y poke im (y-siz - y * x-siz + x) color ] calc-pixel: func [xPixel yPixel] [ rmax: 2 itmax: 100 xStart: 0.00 yStart: 0.00 count: 0 r: 0.00 xnew: 0.00 ynew: 0.00 xold: 0.00 yold: 0.00 ;convert to real coordinates ;convert it to a value between -2.0 ... 1.0 xStart: ( xPixel / 100.0 ) - 2.0 ;convert it to a value between -2.0 ... 2.0 yStart: ( yPixel / 100.0 ) - 2.0 xold: xStart yold: yStart count: 0 r: 0.0 flag: 2 while [flag > 1 ][ flag: 0 if ( r <= rmax )[flag: flag + 1 ] if ( count < itmax ) [flag: flag + 1 ] xnew: (xold * xold) - (yold * yold) + xStart ynew: (2.0 * xold * yold) + yStart r: square-root ((xnew * xnew) + (ynew * ynew)) xold: xnew yold: ynew count: count + 1 ] bol: false if (r < rmax)[ bol: true] return bol ] x-siz: 300 y-siz: 400 im: make image! 300x400 bg-color: 255.255.220 clear-im im bg-color view layout [ img: image im across pad 50 button "Draw" [ clear-im im bg-color repeat x x-siz [ repeat y y-siz [ if calc-pixel x y [ set-pixel im x y blue ] ] show img ] show img ] button "Quit" [quit] ]