Simple paddleball game, ball not bouncing-CodePudding

I'm following Python 4 kids and in it we create a simple paddleball game. I previously was able to get the ball to bounce off the walls, but now at the end of the chapter it no longer works. I don't see any errors in the terminal either when I run the file.

from tkinter import *
import random
import time

class Ball:
    def __init__(self, canvas, paddle, color):
        self.canvas = canvas
        self.paddle = paddle
        self.id = canvas.create_oval(10, 10, 25, 25, fill=color)
        self.canvas.move(self.id, 245, 100)
        starts = [-3, -2, -1, 1, 2, 3]
        self.x = random.choice(starts)
        self.y = -1
        self.canvas_height = self.canvas.winfo_height()
        self.canvas_width = self.canvas.winfo_width()
        self.hit_bottom = False
    
    def hit_paddle(self, pos):
        paddle_pos = self.canvas.coords(self.paddle.id)
        if pos[2] >= paddle_pos[0] and pos[0] <= paddle_pos[2]:
            if pos[3] >= paddle_pos[1] and pos[3] <= paddle_pos[3]:
                return True
        return False
    
    def draw(self):
        self.canvas.move(self.id, self.x, self.y)
        pos = self.canvas.coords(self.id)
        if pos[1] <= 0:
            self.y = self.y * -1
        if pos[3] >= self.canvas_height:
            self.hit_bottom = True
        if self.hit_paddle(pos) == True:
            self.y = self.y * -1
        if pos[0] <= 0 or pos[2] >= self.canvas_width:
            self.y = self.y * -1
        
        
class Paddle:
    def __init__(self, canvas, color):
        self.canvas = canvas
        self.id = canvas.create_rectangle(0, 0, 100, 10, fill=color)
        self.canvas.move(self.id, 200, 300)
        self.x = 0
        self.canvas_width = self.canvas.winfo_width()
        self.canvas.bind_all('<KeyPress-Left>', self.turn_left)
        self.canvas.bind_all('<KeyPress-Right>', self.turn_right)
    
    def draw(self):
        self.canvas.move(self.id, self.x, 0)
        pos = self.canvas.coords(self.id)
        if pos[0] <= 0 or pos[2] >= self.canvas_width:
            self.x = 0
    
    def turn_left(self, evt):
        self.x = -2
    
    def turn_right(self, evt):
        self.y = 2

tk = Tk()
tk.title('Bounce Game')
tk.resizable(0, 0)
tk.wm_attributes('-topmost', 1)
canvas = Canvas(tk, width=500, height=400, bd=0, highlightthickness=0)
canvas.pack()
tk.update()

paddle = Paddle(canvas, 'blue')
ball = Ball(canvas, paddle, 'red' )

while True:
    if ball.hit_bottom == False:
        ball.draw()
        paddle.draw()
    tk.update_idletasks()
    tk.update()
    time.sleep(0.01)

tk.mainloop()

The ball should bounce off the walls and the paddle.

CodePudding user response：

its just an oversight in which coordinate you need to reverse.

The problem lies in the draw function in the ball class

def draw(self):
    self.canvas.move(self.id, self.x, self.y)
    pos = self.canvas.coords(self.id)
    if pos[1] <= 0:
        self.y = self.y * -1
    if pos[3] >= self.canvas_height:
        self.hit_bottom = True
    if self.hit_paddle(pos) == True:
        self.y = self.y * -1
    if pos[0] <= 0 or pos[2] >= self.canvas_width:
        self.y = self.y * -1

In the last if statement you say that if the ball has reached the left or right boundary of the screen, then we want to reverse the y coordinate. What you actually want to do is reverse the x coordinate!

The fix is simply changing...

if pos[0] <= 0 or pos[2] >= self.canvas_width:
    self.y = self.y * -1

to...

if pos[0] <= 0 or pos[2] >= self.canvas_width:
    self.x = self.x * -1

And some additional changes for your code to be more readable could be

def draw(self):
    self.canvas.move(self.id, self.x, self.y)
    pos = self.canvas.coords(self.id)

    if pos[1] <= 0 or self.hit_paddle(pos):
        self.y = -self.y

    if pos[3] >= self.canvas_height:
        self.hit_bottom = True

    if pos[0] <= 0 or pos[2] >= self.canvas_width:
        self.x = -self.x

CodePudding user response：

Maybe the turn_right method should be self.x = 2