乒乓球碰撞检测器（桨到球）

Question

我想在这个程序（乒乓球游戏）中添加一个碰撞检测器，我不知道碰撞检测的语法。我目前有一个桨、球和一个用于桨的鼠标监听器（感谢 s/o）。目前我正在尝试在桨上添加一个碰撞检测器，这样我就可以以随机方向击回球。这是我的代码；

问题：在球和桨之间添加碰撞检测器的语法是什么？

非常感谢。

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.event.MouseMotionListener;


public class PongGame extends JFrame implements Runnable,MouseMotionListener{

  int ball_x, ball_y, ball_dx, ball_dy;
  int ball_r;

  int x_left, x_right, y_top, y_bottom;

  int paddle_y = 30;

  /**
   * Constructor
   */

  public PongGame(){
    init();
  }

  /**
   * this is where we set up the UI
   */
  public void init(){
    this.setSize(300,300);
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    this.addMouseMotionListener(this);

    ball_x = this.getWidth()/2;
    ball_y = this.getHeight()/2;
    ball_dx = ball_dy = 2;
    ball_r = 20;

    this.setVisible(true);
    getFocus(this);


    x_left = this.getInsets().left;
    x_right = this.getWidth() - this.getInsets().right - ball_r;
    y_top = this.getHeight() - this.getInsets().top + ball_r/3;
    y_bottom = this.getInsets().bottom + ball_r;
  }

  /**
   * helper method which we use to get the focus
   **/
  public void getFocus(final JFrame frame)
  {
      EventQueue.invokeLater(new Runnable() {
              public void run() {
                  frame.requestFocus();
              }
       });
  }

  /**
   * implementation of the Runnable interface to be able to move the ball, etc.
   */
  public void run(){

    while(true){

      ball_x += ball_dx;
      if(ball_x <= x_left || ball_x >= x_right){
        ball_dx *=-1;
        ball_x += (2*ball_dx);
      }

      ball_y += ball_dy;
      if(ball_y <= y_bottom || ball_y >= y_top){
        ball_dy *=-1;
        ball_y += (2*ball_dy);
      }


      repaint();

      try{
        Thread.sleep(50);
      }catch(InterruptedException ex){
        System.out.println(ex);
      }
    }
  }



  /**
   * all rendering occurs here
   */
  public void paint(Graphics g){

    g.setColor(Color.white);
    g.fillRect(0,0,this.getWidth(),this.getHeight());

    g.setColor(Color.black);
    g.fillOval(ball_x,ball_y, ball_r, ball_r);

    g.setColor(Color.black);
    g.fillRect(20,paddle_y,20,70);
  }

     public void mouseMoved(MouseEvent e) {
      }

       public void mouseDragged(MouseEvent e){
         paddle_y = e.getY(); 
       } 

  /**
   * entry point into the program
   */
  public static void main(String[] args){
    // create the class
    PongGame application = new PongGame();
    new Thread(application).start();
  }
}

Answer 1

找到答案了！

       if(ball_x >paddle_x && ball_x < paddle_x + paddle_width)
   {
     if(ball_y>paddle_y && ball_y < paddle_y + paddle_height)
      {
         ball_dx = -ball_dx;
      }
   }

来源：https://www.youtube.com/watch?v=GpM8yvDP21o