用java写的烟火效果

//http://community.csdn.net/Expert/topic/3672/3672834.xml?temp=5.533999E-02

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

public class yanhua extends JComponent implements Runnable{

  Image img; Graphics ig;

  public static void main(String arg[]){

    JFrame f=new JFrame("Paint");

    f.setBackground(Color.black);

    Container c=f.getContentPane();

    Flash flash=new Flash();

    c.add(flash);

    f.pack();

    f.show();

    new Thread(flash).start();   

  }

  public Dimension getPreferredSize(){return (new Dimension(300,300));}

  public void run(){

    int i,j,k; int t=15,per=20,n=t*per; int x[],y[],delay[];

    x=new int[t];y=new int[t];delay=new int[t];

    Color c[]=new Color[t];

    try{Thread.sleep(1000);}catch(Exception e){}

    Fire f[]=new Fire[n];

    for (i=0;i<t;i++){x[i]=(int)(Math.random()*200)+50;y[i]=(int)(Math.random()*100)+50;

      c[i]=new Color((int)(Math.random()*100+150),(int)(Math.random()*100+150),(int)(Math.random()*100+150));

      delay[i]=(int)(Math.random()*50);

    }

    for (i=0;i<n;i++){

      f[i]=new Fire(x[i/per],y[i/per],Math.cos(i*360/per)*30,Math.sin(i*360/per)*30,ig,c[i/per]);

    }

    for (i=0;i<100;i++){

      for (j=0;j<t;j++){

        if (delay[j]>0) delay[j]--;

        else

          for (k=0;k<per;k++){

            f[j*per+k].move();

          }

      }

      try{Thread.sleep(20);}catch(Exception e){}

      getGraphics().drawImage(img,0,0,300,300,null);

      repaint();

    }

  }

  public void paint(Graphics g){

    if (img==null){

      img=createImage(300,300);

      ig=img.getGraphics();

    }

    g.drawImage(img,0,0,300,300,null);

  }

}

class Fire{

  static double ga=9.8, delta=0.05;

  private double dx,dy;

  private double [] x=new double[3],y=new double[3];

  Graphics g; Color c;

  private int cnt;

  public Fire(double x, double y,double xDirection, double yDirection, Graphics g, Color c){

    dx=xDirection;dy=yDirection; this.x[0]=x; this.y[0]=y;

    this.g=g;this.c=c;   

    cnt=0;

  }

  public void move(){

    cnt++;

    if (cnt%20==0) this.c=this.c.darker();

    Color c=this.c; int i;

    for (i=2;;i--){

      g.setColor(Color.black);

      g.fillOval((int)x[i],(int)y[i],3,3);

      if (i==0) break;

      x[i]=x[i-1];y[i]=y[i-1];

    }

    x[0]+=dx*delta; y[0]+=dy*delta; dy+=ga*delta;

    for (i=0;i<3;i++){

      g.setColor(c);

      g.fillOval((int)x[i],(int)y[i],3,3);

      c=c.darker();

    }

  }

}