Flash AS制作小球自由运动和碰撞检测的动画

利用flash Actionscript对小球运动进行管理，并且实现对碰撞的检测的实例代码。

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启动Flash 8，修改文档属性如下图。 字串9

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接着建立影片剪辑，设置如下。 www.yueluo.net

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然后回到主场景中，在第一帧输入下面代码： 字串8

number_of_balls = 6;//可能会引起问题发生的！建议这里最大数为3。我提供的演示有问题了。
speed_limit = 10;//速度的设置。
for (x=1; x<=number_of_balls; x++) {
 ball = attachMovie("ball", "ball_"+x, _root.getNextHighestDepth(), {_x:Math.random()*400-50, _y:Math.random()*300-50});
 ball.collision = 0;
 ball.mass = 1;
 ball.xspeed = Math.random()*8-4;
 ball.yspeed = Math.random()*8-4;
 ball.onEnterFrame = function() {
  if (this._x<15) {
   this._x = 15;
   this.xspeed *= -1;
  }
  else if (this._x>485) {
   this._x = 485;
   this.xspeed *= -1;
  }
  if (this._y<15) {
   this._y = 15;
   this.yspeed *= -1;
  }
  else if (this._y>385) {
   this._y = 385; 字串6
   this.yspeed *= -1;
  }
  if (this.xspeed>speed_limit) {
   this.xspeed = speed_limit;
  }
  if (this.xspeed<speed_limit*-1) {
   this.xspeed = speed_limit*-1;
  }
  if (this.yspeed>speed_limit) {
   this.yspeed = speed_limit;
  }
  if (this.yspeed<speed_limit*-1) {
   this.yspeed = speed_limit*-1;
  }
  this._x += this.xspeed;
  this._y += this.yspeed;
 };
}
function manage_bounce(ball, ball2) {
 dx = ball._x-ball2._x;
 dy = ball._y-ball2._y;
 collisionision_angle = Math.atan2(dy, dx);
 magnitude_1 = Math.sqrt(ball.xspeed*ball.xspeed+ball.yspeed*ball.yspeed);
 magnitude_2 = Math.sqrt(ball2.xspeed*ball2.xspeed+ball2.yspeed*ball2.yspeed);
 direction_1 = Math.atan2(ball.yspeed, ball.xspeed);

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 direction_2 = Math.atan2(ball2.yspeed, ball2.xspeed);
 new_xspeed_1 = magnitude_1*Math.cos(direction_1-collisionision_angle);
 new_yspeed_1 = magnitude_1*Math.sin(direction_1-collisionision_angle);
 new_xspeed_2 = magnitude_2*Math.cos(direction_2-collisionision_angle);
 new_yspeed_2 = magnitude_2*Math.sin(direction_2-collisionision_angle);
 final_xspeed_1 = ((ball.mass-ball2.mass)*new_xspeed_1+(ball2.mass+ball2.mass)*new_xspeed_2)/(ball.mass+ball2.mass);
 final_xspeed_2 = ((ball.mass+ball.mass)*new_xspeed_1+(ball2.mass-ball.mass)*new_xspeed_2)/(ball.mass+ball2.mass);
 final_yspeed_1 = new_yspeed_1;
 final_yspeed_2 = new_yspeed_2;
 ball.xspeed = Math.cos(collisionision_angle)*final_xspeed_1+Math.cos(collisionision_angle+Math.PI/2)*final_yspeed_1;
 ball.yspeed = Math.sin(collisionision_angle)*final_xspeed_1+Math.sin(collisionision_angle+Math.PI/2)*final_yspeed_1;
 ball2.xspeed = Math.cos(collisionision_angle)*final_xspeed_2+Math.cos(collisionision_angle+Math.PI/2)*final_yspeed_2;
 ball2.yspeed = Math.sin(collisionision_angle)*final_xspeed_2+Math.sin(collisionision_angle+Math.PI/2)*final_yspeed_2;
}
_root.onEnterFrame = function() {
 for (x=1; x<number_of_balls; x++) {
  for (y=x+1; y<=number_of_balls; y++) {
   distance_x = Math.abs(_root["ball_"+x]._x-_root["ball_"+y]._x);
   distance_y = Math.abs(_root["ball_"+x]._y-_root["ball_"+y]._y);
   distance = Math.sqrt(distance_x*distance_x+distance_y*distance_y);
   if (distance<=30 && (_root["ball_"+x].collision == 0 or _root["ball_"+y].collision == 0)) {
    _root["ball_"+x].collision = 1;
    _root["ball_"+y].collision = 1;
    manage_bounce(_root["ball_"+x],_root["ball_"+y]);
   }
   else if (distance>30) {

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    _root["ball_"+x].collision = 0;
    _root["ball_"+y].collision = 0;
   }
  }
 }
}; www.yueluo.net

按Ctrl+Enter测试效果如下。

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