重置變量增加它而不是重置它 - Tkinter

Question

我創建了一個使用tkinter作爲一個小項目的Pong遊戲。我寫了遊戲，它完全運作。然而，我遇到了一個奇怪的錯誤，在遊戲結束時，當一個玩家達到3分時，當遊戲重新開始時，球的速度似乎翻倍，並且每次遊戲重置時都會發生這種情況。當遊戲函數被調用時，startgame函數應該將變量dx（球的x移動）設置爲2，所以我不確定爲什麼它每次都會變快2，因爲沒有增加。 我已經發布了下面的整個代碼塊，並完全失去了爲什麼發生這種情況，任何幫助將不勝感激！

from tkinter import * 
root = Tk() 

#size of window 
w = 600 
h = 400 
sw = root.winfo_screenwidth() 
sh = root.winfo_screenheight() 
x = (sw - w)/2 
y = (sh - h)/2 
root.geometry('%dx%d+%d+%d' % (w, h, x, y)) 

#playing frame, with Canvas inside 
canvframe = Frame(relief=SUNKEN, width=600, height = 350, background="black") 
canvframe.pack() 

canv = Canvas(canvframe, background="black", width=600, height = 350) 
canv.pack(fill=NONE) 

# Objects in canvas   
ball = canv.create_oval(300,160,310,170, outline="white", fill="white", width=2, tags=('ball')) 
paddle1 = canv.create_rectangle(0,200,10,120, outline="white", fill="white", width=2, tags=('paddle1')) 
paddle2 = canv.create_rectangle(590,200,600,120, outline="white", fill="white", width=2) 

#Paddle movement  
def moveUp1(event): 
    canv.move(paddle1, 0, -10)   
    pass 
def moveUp2(event): 
    canv.move(paddle2, 0, -10)   
    pass 
def moveDown1(event): 
    canv.move(paddle1, 0, 10)   
    pass 
def moveDown2(event): 
    canv.move(paddle2, 0, 10)   
    pass 

#InitialVelocity 
dx = 0 
dy = 0 

#initial score 
Player1score = 0 
Player2score = 0 

#start game - what happens when you push start button (reset velocity and scores) 
def startgame(): 
    global dy, dx, Player1score, Player2score 
    canv.coords(paddle1, 0,200,10,120) 
    canv.coords(paddle2, 590,200,600,120) 
    dx = 2 
    dy = 0 
    Player1score = 0 
    Player2score = 0 
    Player1scoreLabel.configure(text="Score: "+ str(Player1score)) 
    Player2scoreLabel.configure(text="Score: "+ str(Player2score)) 
    moveBall() 

#Ball Movement 
def moveBall(): 
    global dy, dx, Player1score, Player2score 
# to make ball bounce off paddle 1 
    if canv.coords(ball)[0]<=canv.coords(paddle1)[2] and canv.coords(paddle1)[1]<= canv.coords(ball)[1] <= canv.coords(paddle1)[3]:   
     dx = -dx 
     if canv.coords(paddle1)[1] <= canv.coords(ball)[1] <= (int((canv.coords(paddle1)[1] + canv.coords(paddle1)[3]))/2): 
      dy -=1 
      canv.move(ball, dx, dy) 
     elif (int(canv.coords(paddle1)[1] + canv.coords(paddle1)[3])/2) <= canv.coords(ball)[3] <= canv.coords(paddle1)[3]: 
      dy += 1 
      canv.move(ball, dx, dy) 
     else: 
      canv.move(ball, dx, dy) 
# to make ball bounce off paddle 2 
    elif canv.coords(ball)[2]>=canv.coords(paddle2)[0] and canv.coords(paddle2)[1]<= canv.coords(ball)[3] <= canv.coords(paddle2)[3]: 
     dx = -dx 
     if canv.coords(paddle2)[1] <= canv.coords(ball)[1] <= (int((canv.coords(paddle2)[1] + canv.coords(paddle2)[3]))/2): 
      dy -= 1 
      canv.move(ball, dx, dy) 
     elif (int(canv.coords(paddle2)[1] + canv.coords(paddle2)[3])/ 2) <= canv.coords(ball)[3] <= canv.coords(paddle2)[3]: 
      dy += 1 
      canv.move(ball, dx, dy) 
     else: 
      canv.move(ball, dx, dy) 
#  to make ball bounce off roof 
    elif canv.coords(ball)[1]<=0: 
     dy = -dy 
     canv.move(ball, dx, dy) 
#  to mkae ball bounce of floor 
    elif canv.coords(ball)[1]>=325: 
     dy = -dy 
     canv.move(ball, dx, dy) 
#  if player 2 scores 
    elif canv.coords(ball)[2]<=0: 
     Player2score += 1 
     Player2scoreLabel.configure(text="Score: "+ str(Player2score)) 
     canv.coords(ball, 300,160,310,170) 
     canv.coords(paddle1, 0,200,10,120) 
     canv.coords(paddle2, 590,200,600,120) 
     dx=2 
     dy=0 
#  if player1 scores 
    elif canv.coords(ball)[0]>=600: 
     Player1score += 1 
     Player1scoreLabel.configure(text="Score: "+ str(Player1score)) 
     canv.coords(ball, 300,160,310,170) 
     canv.coords(paddle1, 0,200,10,120) 
     canv.coords(paddle2, 590,200,600,120) 
     dx=-2 
     dy=0 
#  end game if player 1 wins 
    elif Player1score==3: 
     dx=0 
     dy=0 
#  end game if player 2 wins 
    elif Player2score==3: 
     dx=0 
     dy=0 
#  move ball if nothign happens 
    else:   
     canv.move(ball, dx, dy) 
    canv.after(10, moveBall) 

#buttons 
Butframe = Frame(relief=SUNKEN, width=200, height = 150, background="white") 
Butframe.pack() 
startButton = Button(Butframe, text="Start", command = startgame) 
startButton.pack(side=LEFT) 
quitButton = Button(Butframe, text="Quit", command=root.destroy) 
quitButton.pack(side=LEFT) 

#scores 
Score1frame = Frame(relief=SUNKEN, width=200, height = 150, background="white") 
Score1frame.pack(side=LEFT)  
Player1scoreLabel = Label(Score1frame, text="Score: "+ str(Player1score), background="green") 
Player1scoreLabel.pack() 
Score2frame = Frame(relief=SUNKEN, width=200, height = 150, background="white") 
Score2frame.pack(side=RIGHT) 
Player2scoreLabel = Label(Score2frame, text="Score: "+ str(Player2score), background="green") 
Player2scoreLabel.pack() 

#binding of movement keys  
root.bind("<Up>", moveUp2) 
root.bind("<w>", moveUp1) 
root.bind("<Down>", moveDown2) 
root.bind("<s>", moveDown1) 
root.mainloop() 

Answer 1

你的表觀速度增加的原因是重疊呼叫到.after()方法。

當一個玩家贏了，你應該使用gameover稱爲全局變量像下面停止循環中moveBall()，例如：

# Initialize gameover variable 
gameover = False 

# (...) (Reset gameover to False in startgame() as well) 

def moveBall(): 
    global dy, dx, Player1score, Player2score, gameover 

    # (...) 

    # end game if player 1 or 2 wins 
    elif Player1score==3 or Player2score==3: 
     dx=0 
     dy=0 
     gameover = True 
    # move ball if nothing happens 
    else:   
     canv.move(ball, dx, dy) 

    # Repeat until game is over 
    if not gameover: 
     canv.after(10, moveBall)