forked from: 複数のオブジェクトへのバネの割り当て

/**
 * Copyright _wonder ( http://wonderfl.net/user/_wonder )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/aWRp
 */

// forked from _wonder's 複数のオブジェクトへのバネの割り当て
// forked from _wonder's バネ運動
// forked from _wonder's base
package {
    import flash.display.Sprite;
    import flash.events.Event;
    import flash.events.MouseEvent;
    
    public class Spring extends Sprite {
    		private var ball0:Ball;
    		private var ball1:Ball;
    		private var ball2:Ball;
    		private var ball0Dragging:Boolean = false;
    		private var ball1Dragging:Boolean = false;
    		private var ball2Dragging:Boolean = false;
    		private var spring:Number = 0.1;
    		private var friction:Number = 0.95;
    		private var springLength:Number = 100;
    		
    		public function Spring() {
            init();
        }
        
        private function init():void {
        		ball0 = new Ball(20);
        		ball0.x = Math.random() * stage.stageWidth;
        		ball0.y = Math.random() * stage.stageHeight;
        		ball0.addEventListener(MouseEvent.MOUSE_DOWN, onPress);
        		addChild( ball0 );
        		
        		ball1 = new Ball(20);
        		ball1.x = Math.random() * stage.stageWidth;
        		ball1.y = Math.random() * stage.stageHeight;
        		ball1.addEventListener(MouseEvent.MOUSE_DOWN, onPress);
        		addChild( ball1 );
        		
        		ball2 = new Ball(20);
        		ball2.x = Math.random() * stage.stageWidth;
        		ball2.y = Math.random() * stage.stageHeight;
        		ball2.addEventListener(MouseEvent.MOUSE_DOWN, onPress);
        		addChild( ball2 );
        		
        		addEventListener(Event.ENTER_FRAME, onEnterFrame);
        		stage.addEventListener(MouseEvent.MOUSE_UP, onRelease);
        }
        
        private function onEnterFrame(e:Event):void {
        		if(!ball0Dragging){
        			springTo(ball0,ball1);
        			springTo(ball0,ball2);
        		}
        		if(!ball1Dragging){
        			springTo(ball1, ball0);
        			springTo(ball1, ball2);
        		}
        		if(!ball2Dragging){
        			springTo(ball2, ball0);
        			springTo(ball2, ball1);
        		}
        		
        		graphics.clear();
        		graphics.lineStyle(1);
        		graphics.moveTo(ball0.x, ball0.y);
        		graphics.lineTo(ball1.x, ball1.y);
        		graphics.lineTo(ball2.x, ball2.y);
        		graphics.lineTo(ball0.x, ball0.y);
        }
        
        private function springTo(ballA:Ball, ballB:Ball):void {
        		var dx:Number = ballB.x - ballA.x;
        		var dy:Number = ballB.y - ballA.y;
        		var angle:Number = Math.atan2( dy, dx );
        		var targetX:Number = ballB.x - Math.cos( angle ) * springLength;
        		var targetY:Number = ballB.y - Math.sin( angle ) * springLength;
        		ballA.vx += (targetX - ballA.x) * spring;
        		ballA.vy += (targetY - ballA.y) * spring;
        		ballA.vx *= friction;
        		ballA.vy *= friction;
        		ballA.x += ballA.vx;
        		ballA.y += ballA.vy;
        }
        
        private function onPress(e:MouseEvent):void {
        		e.target.startDrag();
        		if(e.target == ball0){
        			ball0Dragging = true;
        		}
        		if(e.target == ball1){
        			ball1Dragging = true;
        		}
        }
        
        private function onRelease(e:MouseEvent):void {
        		ball0.stopDrag();
        		ball1.stopDrag();
        		ball0Dragging = false;
        		ball1Dragging = false;
        }
    }
}

import flash.display.Sprite;

class Ball extends Sprite {
	public var radius:Number;
	public var color:uint;
	public var vx:Number = 0;
	public var vy:Number = 0;
	
	public function Ball(radius:Number=40, color:uint=0Xff0000){
		this.radius = radius;
		this.color = color;
		init();
	}
	
	public function init():void {
		graphics.beginFill(color);
		graphics.drawCircle(0, 0, radius);
		graphics.endFill();
	}
}