Interactive Pythagoras Tree
Interactive Pythagoras Tree
// Interactive Pythagoras Tree
package {
import flash.display.Graphics;
import flash.display.Sprite;
import flash.geom.Matrix;
import flash.geom.Point;
public class FlashTest extends Sprite {
private var count:Number = 0;
private var left:Point = new Point;
private var rotor:Matrix = new Matrix;
private var s1:Point = new Point, s2:Point = new Point;
// check out http://en.wikipedia.org/wiki/Pythagoras_tree
private function ptree (at:Point, up:Point, g:Graphics):void {
count += 1;
// draw the square according to given position and direction
left.x = -up.y; left.y = up.x;
g.beginFill (0x31007*count);
g.moveTo (at.x + up.x + left.x, at.y + up.y + left.y);
g.lineTo (at.x + up.x - left.x, at.y + up.y - left.y);
g.lineTo (at.x - up.x - left.x, at.y - up.y - left.y);
g.lineTo (at.x - up.x + left.x, at.y - up.y + left.y);
g.endFill ();
// calculate radius
var r:Point = rotor.transformPoint (up);
// calculate half-sides
s1.x = (r.x - left.x) * 0.5; s1.y = (r.y - left.y) * 0.5;
s2.x = (r.x + left.x) * 0.5; s2.y = (r.y + left.y) * 0.5;
// calculate directions
var d1:Point = new Point (-s1.y, s1.x);
var d2:Point = new Point (s2.y, -s2.x);
// calculate positions of new squares
var p1:Point = new Point (at.x + up.x + s2.x + d1.x, at.y + up.y + s2.y + d1.y);
var p2:Point = new Point (at.x + up.x + s1.x + d2.x, at.y + up.y + s1.y + d2.y);
// repeat twice
if (count < 10) {
ptree (p1, d1, g);
ptree (p2, d2, g);
}
count -= 1;
}
public function FlashTest() {
addEventListener("enterFrame", onEnterFrame);
}
private function onEnterFrame (e:*):void {
rotor.identity ();
rotor.rotate (2.0 * (mouseX - stage.stageWidth * 0.5) / stage.stageWidth);
graphics.clear ();
ptree (new Point (230, 340), new Point (0, -40), graphics);
}
}
}