多物体碰撞检测

文档类

package {
	import flash.display.Sprite;
	import flash.events.Event;

	/**
	 * ...多物体碰撞检测
	 * @author zkl
	 * 来自:Action Script3.0 Animation
	 */
	public class Bubbles2 extends Sprite {
		private var balls:Array;
		private var centerBall:Ball;
		private var numBalls:Number = 10;
		private var bounce:Number = -1;
		private var spring:Number = 0.2;
		private var gravity:Number = 0.1;

		public function Bubbles2():void {
			init();
		}

		private function init():void {
			balls = new Array;

			for (var i:uint = 0; i < numBalls; i++){
				var ball:Ball = new Ball(Math.random() * 40 + 5, Math.random() * 40 + 5);
				ball.x = Math.random() * stage.stageWidth;
				ball.y = Math.random() * stage.stageHeight;
				ball.vx = Math.random() * 6 - 3;
				ball.vy = Math.random() * 6 - 3;
				addChild(ball);
				balls.push(ball);
			}
			addEventListener(Event.ENTER_FRAME, EnterFrame);
		}

		private function EnterFrame(e:Event):void {
			//A球碰B球
			for (var i:uint = 0; i < balls.length - 1; i++){
				var ballA:Ball = balls[i];
				for (var j:uint = i + 1; j < balls.length; j++){
					var ballB:Ball = balls[j];
					var dx:Number = ballB.x - ballA.x;
					var dy:Number = ballB.y - ballA.y;
					var dist:Number = Math.sqrt(dy * dy + dx * dx);
					var minDist:Number = ballB.radius + ballA.radius;
					if (dist < minDist){
						var angle:Number = Math.atan2(dy, dx);
						var tx:Number = ballA.x + Math.cos(angle) * minDist;
						var ty:Number = ballA.y + Math.sin(angle) * minDist;
						//计算加速度
						var ax:Number = (tx - ballB.x) * spring;
						var ay:Number = (ty - ballB.y) * spring;
						//AB球加速度相反
						ballA.vx -= ax;
						ballA.vy -= ay;
						ballB.vx += ax;
						ballB.vy += ay;
					}
				}
			}
			for (i = 0; i < numBalls; i++){
				var ball:Ball = balls[i];
				move(ball);
			}
		}

		private function move(ball:Ball):void {
			//ball.vy += gravity;
			ball.x += ball.vx;
			ball.y += ball.vy;
			if (ball.x + ball.radius > stage.stageWidth){
				ball.x = stage.stageWidth - ball.radius;
				ball.vx *= bounce;
			} else if (ball.x - ball.radius < 0){
				ball.x = ball.radius;
				ball.vx *= bounce;
			}
			if (ball.y + ball.radius > stage.stageHeight){
				ball.y = stage.stageHeight - ball.radius;
				ball.vy *= bounce;
			} else if (ball.y - ball.radius < 0){
				ball.y = ball.radius;
				ball.vy *= bounce;
			}
		}

	}

}