flash中物体运动基础之五障碍物

障碍物有的可以运动有的不能运动，如：可以把墙壁看出不能运动的障碍物，移动的另一个球体看出运动的障碍物。运动过程中要检测球体是否与障碍物接触，可以用hitTestObject方法或者hitTestPoint方法。

接着第四部分，修改update函数。在舞台上增加了obstruction1，obstruction2，obstruction3。

obstruction1为上下运动的矩形
obstruction2为舞台下方的浅蓝色矩形，模拟液体物质。
obstruction3为转动的矩形

private function update(e:Event):void 
		{
			hitTestObstruction3();
			if (
				wallLeft.hitTestObject(_ball) ||
				wallRight.hitTestObject(_ball) ||
				wallTop.hitTestObject(_ball)||
				wallBottom.hitTestObject(_ball) ||
				obstruction1.hitTestObject(_ball)
			)
			{
				_ball.reset(_ballInitX, _ballInitY);
				_score-= 2;
			}
			
			hitTestCoin();
			hitTestObstruction1();
			hitTestObstruction2();
			updateScore();
		}
		
		private function updateScore():void
		{
			scoreText.text = _score.toString();
		}
		
		private function hitTestObstruction3():void
		{
			obstruction3.rotation += 0.5;
			
			if (obstruction3.hitTestPoint(_ball.x,_ball.y,true))
			{
				_ball.reset(_ballInitX, _ballInitY);
				_score-= 2;
			}
		}
		
		private function hitTestObstruction2():void
		{
			if (obstruction2.hitTestObject(_ball))
			{
				_ball.vx = _ball.vx / 1.2;
				_ball.vy = _ball.vy / 1.2;
			}
		}
		
		private function hitTestCoin():void
		{
			_right = wallRight.x - wallRight.width / 2;
			_top = wallTop.y + wallTop.height / 2;
			_left = wallLeft.x + wallLeft.width / 2;
			_bottom = wallBottom.y - wallBottom.height / 2;
			
			var dx:Number = (_ball.x-coin.x) * (_ball.x-coin.x);
			var dy:Number = (_ball.y-coin.y) * (_ball.y-coin.y);
			var dist:Number = (_ball.width / 2 + coin.width / 2) * (_ball.width/2+coin.width/2);
			if (dx+dy<=dist)
			{
				coin.x = Math.random() * (_right-2*coin.width/2 - _left) + _left+coin.width/2;
				coin.y = Math.random() * (_bottom - 2 * coin.height / 2 - _top) + _top + coin.height / 2;
				_score += 3;
			}
			if (obstruction1.hitTestObject(coin))
			{
				coin.x = Math.random() * (_right-2*coin.width/2 - _left) + _left+coin.width/2;
				coin.y = Math.random() * (_bottom - 2 * coin.height / 2 - _top) + _top + coin.height / 2;
			}
		}
		
		private function hitTestObstruction1():void
		{
			var top:Number = _top + obstruction1.height / 2;
			var bottom:Number = _bottom - obstruction1.height / 2;
			var dist:Number = bottom - top;
			obstruction1.y = stage.stageHeight/2+dist/2 * Math.sin(t);
			t += 0.05;
		}

 由于使用的是hitTestPoint和hitTestObject，限制很大，且导致检测碰撞不精确，如果要更精确的碰撞检测可以尝试使用Box2dAs3来改写，以后有时间再来改吧，这里只是记录一些简单的方式检测的代码。