Flash制作技巧：球与直线的碰撞检测

• 
  　　原理很简单，用点到直线的距离进行判断，没加回帧，所以如果加上碰撞反应，会有问题，代码如下：
  

  import fc.math.Degree;
  class Wall {
      private var _wall:MovieClip;
      private var _cenx:Number;
      private var _ceny:Number;
      private var _k:Number;
      private var a1:Number;
      private var b1:Number;
      private var c1:Number;
      public function Wall(w) {
          _wall = w;
          init();
      }
      public function get target():MovieClip {
          return _wall;
      }
      private function init():Void {
          _cenx = _wall._x;
          _ceny = _wall._y;
          _k = Degree.tanD(_wall._rotation);
          a1 = -_k;
          b1 = 1;
          c1 = _k*_cenx-_ceny;
      }
      public function checkCollision(mc):Boolean {
          var x0 = mc._x;
          var y0 = mc._y;
          var r = mc._width/2;
          var t1 = a1*x0+b1*y0+c1;
          var t2 = a1*a1+b1*b1;
          return t1*t1/t2    }
  }
  //test
  import Wall;
  var t1 = [new Wall(line1), new Wall(line2), new Wall(line3), new Wall(line4)];
  setInterval(test, 30);
  function test() {
      for (var i in t1) {
          var t = t1[i].checkCollision(mc);
          if (t) {
              t1[i].target.gotoAndStop(2);
          } else {
              t1[i].target.gotoAndStop(1);
          }
      }
  }

  
  

  　　拖动进行测试: