球为什么不反弹? [英] Why isn't the ball bouncing back?

问题描述

我正在制作一个简单的乒乓球游戏，但是当球从天花板上掉下来时，它不会来回弹跳.它只是从屏幕上消失.我无法弄清楚为什么会这样！我只关心球从屏幕的顶部和底部弹起，我希望它以直线路径来回弹跳.任何帮助表示赞赏！

I'm making a simple pong game, but when the ball drops from the ceiling, it doesn't bounce back and forth. It just goes off the screen. I can't figure out why this is happening! I am only concerned with the ball bouncing off the top and bottom of the screen and I want it to bounce back and forth in a straight path. Any help is appreciated!

我发现了问题！感谢大家的帮助！

I've found the problem! Thanks for all the help!

这是我的基本代码:

import math
import random
import sys, pygame
from pygame.locals import *

import ball
import colors
import paddle

# draw the scene
def draw(screen, ball1, paddle1) :
   screen.fill((128, 128, 128))
   ball1.draw_ball(screen)
   paddle1.draw_paddle(screen)

#function to start up the main drawing
def main():

   pygame.init()
   width = 600
   height = 600
   screen = pygame.display.set_mode((width, height))

   ball1 = ball.Ball(300, 1, 40, colors.YELLOW, 0, 5)
   paddle1 = paddle.Paddle(250, 575, colors.GREEN, 100, 20)

   while 1:
      for event in pygame.event.get():
         if event.type == QUIT: sys.exit()
         elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_RIGHT:
               paddle1.update_paddle('right', 20)
            if event.key == pygame.K_LEFT:
               paddle1.update_paddle('left', 20)

      ball1.test_collide_top_ball(600)
      ball1.test_collide_bottom_ball(0)
      ball1.update_ball()
      draw(screen, ball1, paddle1)
      pygame.display.flip()

if __name__ == '__main__':
   main()

这是我的球类/方法代码:

And here is my code for the ball class/methods:

import pygame

class Ball:
   def __init__(self, x, y, radius, color, dx, dy):
      self.x = x
      self.y = y
      self.radius = radius
      self.color = color
      self.dx = dx
      self.dy = dy

   def draw_ball(self, screen):
      pygame.draw.ellipse(screen, self.color,
         pygame.Rect(self.x, self.y, self.radius, self.radius))

   def update_ball(self):
      self.x += self.dx
      self.y += self.dy

   def test_collide_top_ball(self, top_height):
      if (self.y >= top_height):
         self.dy *= -1

   def test_collide_bottom_ball(self, coll_height):
      if (self.y >= coll_height):
         self.dy *= -1

推荐答案

您的测试碰撞函数返回速度值.你永远不会在任何地方使用它.

Your test collide functions return the value of velocity. You never use it anywhere.

您使用 dx=0 dy=5 调用更新球.

You call the update ball with dx=0 dy=5.

与其在碰撞后返回 a 值，不如将 dx 和 dy 保存在对象中.所以它会变成:

Instead of returning the a value after collision, it would be better to hold the dx and dy in the object. So it would become:

class Ball:
   def __init__(self, x, y, radius, color):
      self.x = x
      self.y = y
      self.radius = radius
      self.color = color
      self.dx = 0
      self.dy = 5

   def draw_ball(self, screen):
      pygame.draw.ellipse(screen, self.color,
         pygame.Rect(self.x, self.y, self.radius, self.radius))

   def update_ball(self):
      self.x += self.dx
      self.y += self.dy

   def test_collide_top_ball(self, top_height):
      if (self.y >= top_height):
         self.dy *= -1

   def test_collide_bottom_ball(self, coll_height):
      if (self.y >= coll_height):
         self.dy *= -1

这篇关于球为什么不反弹?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！