spring ball

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license : MIT License
modified : 2010-11-03 22:58:17

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//「ActionScript3.0」アニメーション参照
package
{
    import flash.display.Sprite;
    import flash.events.Event;
    import flash.events.MouseEvent;
    
    public class Main extends Sprite
    {
        private var ball0:Ball;
        private var ball1:Ball;
        private var ball0Dragging:Boolean = false;
        private var ball1Dragging:Boolean = false;
        private var spring:Number = 0.04;
        private var gravity:Number = .5;
        private var friction:Number = 0.95;
        private var springLength:Number = 100;
        
        
        private var bounce:Number = -0.7;
        
        public function Main()
        {
            init();
        }
        
        private function init():void
        {
            
            ball0 = new Ball(20,0x000000);
            ball0.x = Math.random() * stage.stageWidth;
            ball0.y = Math.random() * stage.stageHeight;
            ball0.addEventListener(MouseEvent.MOUSE_DOWN, downHandler);
            addChild(ball0);
            
            ball1 = new Ball(20,0x000000);
            ball1.x = Math.random() * stage.stageWidth;
            ball1.y = Math.random() * stage.stageHeight;
            ball1.addEventListener(MouseEvent.MOUSE_DOWN, downHandler);
            addChild(ball1);
            
            addEventListener(Event.ENTER_FRAME, onEnterFrame);
            stage.addEventListener(MouseEvent.MOUSE_UP, upHandler);
        }

private function onEnterFrame(event:Event):void
        {
            if(!ball0Dragging)
            {
                springTo(ball0, ball1);
            }
            if(!ball1Dragging)
            {
                springTo(ball1, ball0);
            }
            graphics.clear();
            graphics.lineStyle(1);
            graphics.moveTo(ball0.x, ball0.y);
            graphics.lineTo(ball1.x, ball1.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.vy+=gravity;
            
            ballA.x += ballA.vx;
            ballA.y += ballA.vy;
            
            var left:Number = 0;
            var right:Number = stage.stageWidth;
            var top:Number = 0;
            var bottom:Number = stage.stageHeight;
            
            if(ballA.x + ballA.radius > right)
            {
                ballA.x = right - ballA.radius;
                ballA.vx *= bounce;
            }
            else if(ballA.x - ballA.radius < left)
            {
                ballA.x = left + ballA.radius;
                ballA.vx *= bounce;
            }
            if(ballA.y + ballA.radius > bottom)
            {
                ballA.y = bottom - ballA.radius;
                ballA.vy *= bounce;
            }
            else if(ballA.y - ballA.radius < top)
            {
                ballA.y = top + ballA.radius;
                ballA.vy *= bounce;
            }
            
            if(ballB.x + ballB.radius > right)
            {
                ballB.x = right - ballB.radius;
                ballB.vx *= bounce;
            }
            else if(ballB.x - ballB.radius < left)
            {
                ballB.x = left + ballB.radius;
                ballB.vx *= bounce;
            }
            if(ballB.y + ballB.radius > bottom)
            {
                ballB.y = bottom - ballB.radius;
                ballB.vy *= bounce;
            }
            else if(ballB.y - ballB.radius < top)
            {
                ballB.y = top + ballB.radius;
                ballB.vy *= bounce;
            }
        }
        
        private function downHandler(event:MouseEvent):void
        {
            event.target.startDrag();
            if(event.target == ball0)
            {
                ball0Dragging = true;
            }
            if(event.target == ball1)
            {
                ball1Dragging = true;
            }
        }
        
        private function upHandler(event: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;
        buttonMode=true;
        useHandCursor=true;
        init();
    }
    public function init():void {
        graphics.beginFill(color);
        graphics.drawCircle(0, 0, radius);
        graphics.endFill();
    }
}

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