[Crash512]

Вот обновочка... Учёл все замечания. Треугольник выровнялся, но всю верёвку немного клонит влево... Не могу понять, почему..=(

package
{
	import flash.display.Shape;
	import flash.display.Sprite;
	import flash.events.Event;
	import flash.events.MouseEvent;
	
	public class Main extends Sprite
	{
		private var pt:Array = new Array();
		private var particles:Sprite = new Sprite();
		private var canvas:Shape = new Shape();
		private var grav:Number = 5;
		
		// ========================================================== //
		public function Main():void
		{
			stage.frameRate = 40;
			
			addChild(canvas);
			
			addChild(particles);
			
			pt.push(new Particle(270,150));
			pt.push(new Particle(270,175));
			pt.push(new Particle(270,200));
			pt.push(new Particle(270,225));
			pt.push(new Particle(270,250));
			pt.push(new Particle(270,275));
			pt.push(new Particle(255,285));
			pt.push(new Particle(285,285));
			
			for (var i in pt)
			{
				particles.addChild(pt[i]);
			}
			
			addEventListener(Event.ENTER_FRAME, checkJoints);
			addEventListener(Event.ENTER_FRAME, ptMouse);
		}
		// ========================================================== //
		private function checkJoints(event:Event):void
		{
			var dx:Number;
			var dy:Number;
			
			canvas.graphics.clear();
			
			// Gravity
			
			for (var i in pt)
			{
				dx = (pt[i].x - pt[i].old_x);
				dy = (pt[i].y - pt[i].old_y) + grav;
				pt[i].old_x = pt[i].x;
				pt[i].old_y = pt[i].y;
				pt[i].x += dx/1.1;
				pt[i].y += dy/1.1;
			}
			
			// Joints
			
			for (var z:int=0; z<5; z++)
			{
				mouseJoint(pt[0], pt[1], 25);
				ptJoint(pt[1], pt[2], 25);
				ptJoint(pt[2], pt[3], 25);
				ptJoint(pt[3], pt[4], 25);
				ptJoint(pt[4], pt[5], 25);
				ptJoint(pt[5], pt[6], 25);
				ptJoint(pt[5], pt[7], 25);
				ptJoint(pt[6], pt[7], 25);
			}
			
			// Lines
			
			drawLine(pt[1], pt[2]);
			drawLine(pt[2], pt[3]);
			drawLine(pt[3], pt[4]);
			drawLine(pt[4], pt[5]);
			drawLine(pt[5], pt[6]);
			drawLine(pt[5], pt[7]);
			drawLine(pt[6], pt[7]);
		}
		// ========================================================== //
		private function ptMouse(event:Event):void
		{
			pt[0].x = mouseX;
			pt[0].y = mouseY;
			drawLine(pt[0], pt[1]);
		}
		// ========================================================== //
		private function mouseJoint(p1:Particle, p2:Particle, len:int):void
		{
			var dx:Number;
			var dy:Number;
			var d_len:Number;
			var diff:Number;

			dx = p2.x-p1.x;
			dy = p2.y-p1.y;
			d_len = Math.sqrt(dx*dx + dy*dy);
			diff = (d_len-len)/d_len;
			dx *= diff;
			dy *= diff;

			p2.x -= dx;
			p2.y -= dy;
		}
		// ========================================================== //
		private function ptJoint(p1:Particle, p2:Particle, len:int):void
		{
			var dx:Number;
			var dy:Number;
			var d_len:Number;
			var diff:Number;
			
			dx = p2.x-p1.x;
			dy = p2.y-p1.y;
			d_len = Math.sqrt(dx*dx + dy*dy);
			diff = (d_len-len)/d_len;
			dx *= 0.5*diff;
			dy *= 0.5*diff;
			
			p2.x -= dx;
			p2.y -= dy;
			p1.x += dx;
			p1.y += dy;
		}
		// ========================================================== //
		private function drawLine(p1:Particle, p2:Particle):void
		{
			canvas.graphics.lineStyle(1,0x000000);
			canvas.graphics.moveTo(p1.x,p1.y);
			canvas.graphics.lineTo(p2.x, p2.y);
		}
		// ========================================================== //
	}
}

// ***** [ Particle Class ] ***************************************** //

import flash.display.Sprite;
	
internal class Particle extends Sprite
{
	public var old_x:Number;
	public var old_y:Number;
	
	// ========================================================== //
	public function Particle(_x:int, _y:int):void
	{
		x = _x;
		y = _y;
		
		old_x = _x;
		old_y = _y;

		graphics.lineStyle(1, 0x000000);
		graphics.beginFill(0xFFD22B);
		graphics.drawCircle(0,0,5);
		graphics.endFill();
	}
	// ========================================================== //
}