java小球弹性碰撞

源码：

package E3;

import java.awt.Color;

import java.awt.Dimension;

import java.awt.Graphics;

import java.awt.Image;

import java.awt.Panel;

import java.awt.event.KeyEvent;

import java.awt.event.KeyListener;

public class drawBall4_3 extends Panel implements Runnable, KeyListener {

    private double x;

 double  dx;

    private double y;

 double dy;

    private double x2,dx2;

    private double y2,dy2;

    private double diameter;

    private int width=400;

    private int height=400;

    private Image im;

    private int xdirection=2,ydirection=2;

   

   

    private int xdirection2=2,ydirection2=2;

  

   

   

    public drawBall4_3() {

     x=5;

        y=50;

        dx=2;

        dy=2;

       

        x2=100;

        y2=10;

        dx2=1;

        dy2=1;

        diameter=30;

      

        setBackground(Color.pink);

        setPreferredSize(new Dimension(width, height));

        addKeyListener(this);

    }

    public void gameStart(){

     Thread gamethread = new Thread(this);

        gamethread.start();

    }

    public void gamePaint() {//前屏显示

        Graphics g;

        g = this.getGraphics();

        g.drawImage(im, 0, 0, null);//从后屏复制到前屏

        g.dispose();//释放当前屏幕Graphcis对象

    }

   

   

    public void gameRender() {//离屏绘制

     

     im = createImage(this.getWidth() , this.getHeight());//建立image对象

     Graphics dbg = im.getGraphics();//获取Graphics对象

        dbg.setColor(Color.pink);//设置绘图属性

        dbg.fillRect(0, 0,width , height);

      

        dbg.setColor(Color.blue);

       dbg.fillOval((int)x, (int)y,(int)diameter,(int)diameter);//绘制图形

       

        dbg.setColor(Color.yellow);

        dbg.fillOval((int)x2, (int)y2,(int)diameter,(int)diameter);//绘制图形

    }

    public void gameUpdate() {

     x+=dx;

     y+=dy;

     x2+=dx2;

     y2+=dy2;

      if(y<0)

       dy=-dy;

     if(y+30>400)

       dy=-dy;

     if(x<0)

      dx=-dx;

     if(x+30>400)

      dx=-dx;

      if(x2<0)

       dx2=-dx2;

     if(x2+30>400)

      dx2=-dx2;

      if(y2<0)

       dy2=-dy2;

     if(y2+30>400)

      dy2=-dy2;

     

     

    if ((x2 - x) * (x2 - x) + (y2 - y) * (y2 - y) <= diameter*diameter) //当两球间的距离小于直径时，可认为两小球发生了碰撞

 {

  double degree = Math.atan((y - y2) / (x - x2)); //获取自己与发生碰撞的小球之间所形成的夹角，因为夹角只能在-pi/2-pi/2之间，所以还需判断两球的x坐标之间的关系

  if (x > x2)  //如果自己的x坐标大于发生碰撞的小球的x坐标，由数学知识可知自己应该往正向运动

  {

   dx = Math.cos(degree); 

   dy = Math.sin(degree);

   x+=dx;

      y+=dy;

      x2+=dx2;

      y2+=dy2;

  }

  else //如果自己的x坐标小于发生碰撞的小球的x坐标，由数学知识可知应该朝负向运动

  {

   dx =-Math.cos(degree);

   dy = -Math.sin(degree);

   x+=dx;

      y+=dy;

      x2+=dx2;

      y2+=dy2;

  }

 

       double degree1 = Math.atan((y2- y) / (x2 - x)); //获取自己与发生碰撞的小球之间所形成的夹角，因为夹角只能在-pi/2-pi/2之间，所以还需判断两球的x坐标之间的关系

  if (x2 > x)  //如果自己的x坐标大于发生碰撞的小球的x坐标，由数学知识可知自己应该往正向运动

  {

   dx2 = Math.cos(degree); 

   dy2= Math.sin(degree);

   x+=dx;

      y+=dy;

      x2+=dx2;

      y2+=dy2;

  }

  else //如果自己的x坐标小于发生碰撞的小球的x坐标，由数学知识可知应该朝负向运动

  {

   dx2 =-Math.cos(degree);

   dy2 =-Math.sin(degree);

   x+=dx;

      y+=dy;

      x2+=dx2;

      y2+=dy2;

  }}

    }

  

    public void run() {

        while(true){

           gameUpdate();

           gameRender();

           gamePaint();

           }

    }

 @Override

 public void keyPressed(KeyEvent arg0) {

  // TODO Auto-generated method stub

  

 }

 @Override

 public void keyReleased(KeyEvent arg0) {

  // TODO Auto-generated method stub

  

 }

 @Override

 public void keyTyped(KeyEvent arg0) {

  // TODO Auto-generated method stub

  

 }}

package E3;

import java.awt.BorderLayout;

import java.awt.event.WindowAdapter;

import java.awt.event.WindowEvent;

import javax.swing.JFrame;

public class GameFrame4_3 {

    public GameFrame4_3() {

        JFrame app = new JFrame("GameFrame4_3");

        app.addWindowListener(new WindowAdapter() {

            public void windowClosing(WindowEvent e) {

                System.exit(0);

            }

        });

        app.setLocation(100, 100);

       app.setLocationRelativeTo(null);

       

        drawBall4_3 drawB = new drawBall4_3();

        app.add(drawB);

       app.add(drawB, BorderLayout.CENTER);

        app.pack();

        app.setVisible(true);

        drawB.gameStart();

    }

    public static void main(String[] args) {

        new GameFrame4_3();

  

    }

}