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# The rope, cubic version.

by makc3d 15 Oct 2013
```// forked from makc3d's The rope.
package {
import flash.display.Sprite;
import flash.geom.Point;
public class FlashTest extends Sprite {
public var a:Vector.<Anchor>;
public function FlashTest() {
// let's try cubic curves
a = new Vector.<Anchor> (2, true);
addChild (a [0] = new Anchor (100, 250));
addChild (a [1] = new Anchor (200, 200));
}
public var c1:Point, v1:Point;
public var c2:Point, v2:Point;
public function loop (...gettingRusty):void {
var r:Number = Math.sqrt(
(a[0].x - a[1].x) * (a[0].x - a[1].x) +
(a[0].y - a[1].y) * (a[0].y - a[1].y)
);
var H:Number = 150;
var cx1:Number = a[0].x + 0.25 * (a[1].x - a[0].x);
var cy1:Number = a[0].y + 0.25 * (a[1].y - a[0].y) + 4 * H * Math.exp(-0.5 * r / H) / 3;
var cx2:Number = a[0].x + 0.75 * (a[1].x - a[0].x);
var cy2:Number = a[0].y + 0.75 * (a[1].y - a[0].y) + 4 * H * Math.exp(-0.5 * r / H) / 3;
if (c1) {
// change speed towards "perfect" centers
var cvx1:Number = cx1 - c1.x;
var cvy1:Number = cy1 - c1.y;
v1.x = 0.95 * (0.9 * v1.x + 0.1 * cvx1);
v1.y = 0.95 * (0.9 * v1.y + 0.1 * cvy1);
c1.x += v1.x;
c1.y += v1.y;
var cvx2:Number = cx2 - c2.x;
var cvy2:Number = cy2 - c2.y;
v2.x = 0.95 * (0.9 * v2.x + 0.1 * cvx2);
v2.y = 0.95 * (0.9 * v2.y + 0.1 * cvy2);
c2.x += v2.x;
c2.y += v2.y;
} else {
c1 = new Point (cx1, cy1); v1 = new Point;
c2 = new Point (cx2, cy2); v2 = new Point;
}
graphics.clear ();
graphics.lineStyle (3, 0x7FFF);
graphics.moveTo (a[0].x, a[0].y);
graphics.cubicCurveTo (c1.x, c1.y, c2.x, c2.y, a[1].x, a[1].y);
}
}
}

import flash.display.Sprite;
import flash.events.MouseEvent;
class Anchor extends Sprite {
public function Anchor (x0:int, y0:int) {
x = x0; y = y0;
graphics.beginFill (0x7FFF, 1);
graphics.drawRect (-6, -6, 12, 12);
useHandCursor = buttonMode = true;
}
public function startDragMe (e:MouseEvent):void {
startDrag ();
}
public function stopDragMe (e:MouseEvent):void {
stopDrag ();
}
}```