// Elastic Pixels 1
// あちこちのコードをパッチワーク
package {
    /**
     * @author YOSHIDA, Akio
     */
    import flash.display.Bitmap;
    import flash.display.BitmapData;
    import flash.display.Sprite;
    import flash.events.Event;
    import flash.events.MouseEvent;
    import flash.geom.Point;
    [SWF(width = "465", height = "465", frameRate = "60", backgroundColor = "#000000")]
    
    public class Main1 extends Sprite {
        
        private var aryParticle:Array;    // パーティクル格納配列
        
        private var row:uint = 60;    // 横方向の数
        private var col:uint = 60;    // 縦方向の数
        
        private var isMouseDown:Boolean = false;    // マウスをダウンしているか否か
        private var distanceOfReaction:uint = 75;    // マウスに反応する距離
        private var spring:Number = 0.048;        // バネ係数
        private var friction:Number = 0.94;        // 摩擦係数

private var canvas:BitmapData;

// コンストラクタ
        public function Main1() {
            var w:uint = stage.stageWidth;
            var h:uint = stage.stageHeight;

canvas = new BitmapData(w, h, false, 0x000000);
            addChild(new Bitmap(canvas));
            
            var interval:uint = 5;
            var offsetX:Number = (w - (row - 1) * interval) / 2;
            var offsetY:Number = (h - (col - 1) * interval) / 2;
            aryParticle = [];
            for (var i:int = 0; i < row; i++) {
                for (var j:int = 0; j < col; j++) {
                    var particle:Particle = new Particle(interval * i + offsetX, interval * j + offsetY);
                    aryParticle.push(particle);
                }
            }
            
            stage.addEventListener(MouseEvent.MOUSE_DOWN, mouseDownHandler);
            stage.addEventListener(MouseEvent.MOUSE_UP, mouseUpHandler);
            addEventListener(Event.ENTER_FRAME, enterFrameHandler);
        }
        
        private function enterFrameHandler(e:Event):void {
            canvas.lock();
            canvas.fillRect(canvas.rect, 0x000000);
            var mousePoint:Point = new Point(mouseX, mouseY);
            for each (var particle:Particle in aryParticle) {
                particle.update(mousePoint, isMouseDown, distanceOfReaction, spring, friction);
                canvas.setPixel(particle.x, particle.y, 0xffcc00);
            }
            canvas.unlock();
        }
        private function mouseDownHandler(e:MouseEvent):void {
            isMouseDown = true;
        }
        private function mouseUpHandler(e:MouseEvent):void {
            isMouseDown = false;
        }
        
    }
    
}

import flash.geom.Point;

class Particle {
    // 既定座標
    private var localX:Number;
    private var localY:Number;
    // ベロシティ
    private var vx:Number = 0;
    private var vy:Number = 0;
    // 現在座標
    private var _x:Number;
    private var _y:Number;
    
    public function Particle(x:Number, y:Number) {
        _x = localX = x;
        _y = localY = y;
    }
    
    public function update(mousePoint:Point, isMouseDown:Boolean, distanceOfReaction:uint, spring:Number, friction:Number):void {
        // 到達値
        var dx:Number;
        var dy:Number;

var distance:Number = Point.distance(mousePoint, new Point(localX, localY));
        var direction:Number = isMouseDown ? 1 : -1;
        
        if (distance < distanceOfReaction) {
            var diff:Number     = distance * direction * (distanceOfReaction - distance) / distanceOfReaction;
            var radian:Number   = Math.atan2(mousePoint.y - localY, mousePoint.x - localX);
            var diffPoint:Point = Point.polar(diff, radian);
            dx = localX + diffPoint.x;
            dy = localY + diffPoint.y;
        } else{    // 位置を元に戻す
            dx = localX;
            dy = localY;
        }
        
        vx += (dx - _x) * spring;
        vy += (dy - _y) * spring;
        vx *= friction;
        vy *= friction;
        _x += vx;
        _y += vy;
    }

public function get x():Number { return _x; }
    public function get y():Number { return _y; }
}