var target_alpha = max_alpha-distance;
if (target_alpha
{
target_alpha = min_alpha;
}
var next_alpha = this._alpha+((target_alpha-this._alpha)/speed);
return next_alpha;
}
function fluidsystem ()
{
var next_scale = setscale(); //这里调用前面的函数给变量赋值
var next_alpha = setalpha();
this._xscale = next_scale; //定义剪辑的缩放大小
