简单的实现雪花的十几行as代码

最新推荐文章于 2022-05-14 08:00:00 发布

原创最新推荐文章于 2022-05-14 08:00:00 发布 · 653 阅读

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#AS #as

看网上的雪花，三方库的，粒子系统，看着很高深复杂，我觉得有点杀鸡用牛刀。

我耍了小聪明，一共三种轨迹，正弦曲线，两种抛物线，然后两种曲线求导（自己求导），得到刚好是x y坐标的变化量程序可以更简单

package
{
import flash.display.GradientType;
import flash.display.Shape;
import flash.display.SpreadMethod;
import flash.display.Sprite;
import flash.events.Event;
import flash.geom.Matrix;
import flash.net.SharedObject;

[SWF(width=960,height=560,backgroundColor="#000000")]
public class test_snow extends Sprite
{
  private var snow_list:Array = new Array();
  private var i:int = 0;

  private static const NUM:int = 300;
  private var r:int = 1;
  public function test_snow()
  {
   addEventListener(Event.ENTER_FRAME,onEnterFrame);
   for(i = 0; i<NUM; i++)
   {
    var circle:Shape = new Shape();
    var x:int = Math.random()*960;
    var y:int = Math.random()*560;

    var temp:int = Math.random();
    if(Math.random() > 0.3)
    {
     circle.alpha = 0.5;
    }
    if(Math.random() <0.3)
    {
     circle.alpha = 0.8;
    }
    circle.x = x;
    circle.y = y;
    snow_list.push(circle);
    draweEllipse(circle,0, 0);
   }
  }

  private function draweEllipse(circle:Shape, x:int, y:int):void
  {
   circle.graphics.beginFill(0xffffff);
   if(i % 2 == 0)
   {
    r = 2.5;
   }
   else if(i % 7 || i % 3 == 0)
   {
    r = 2;
   }
   else
   {
    r = 1.5;
   }
   circle.graphics.drawCircle(x,y,r);
   circle.graphics.endFill();
   addChild(circle);
  }

  private function onEnterFrame(event:Event):void
  {
   for(i = 0;i < NUM;i++)
   {
    if(i % 5 == 0)
    {
     snow_list[i].y += 1;
     snow_list[i].x += 2*Math.cos(snow_list[i].y/20.0);
    }
    else if(i % 3 == 0)
    {
     snow_list[i].y += 2;
     snow_list[i].x -= 0.005*snow_list[i].y;
    }
    else if(i % 7 == 0 )
    {
     snow_list[i].y += 2;
     snow_list[i].x += 0.005*snow_list[i].y;
    }
    else
    {
     snow_list[i].y += 1.5;
    }
    if(snow_list[i].x + r >= stage.stageWidth)
    {
     snow_list[i].x = Math.random()*960;
     snow_list[i].y = 1;
    }
    if(snow_list[i].y + r >= stage.stageHeight)
    {
     snow_list[i].y = 1;
    }
    if(snow_list[i].x <= 0)
    {
     snow_list[i].x = stage.stageWidth;
    }
   }
  }