Simple Pong Tutorial using Turtle by Peter Kwak, edited by Topher Pedersen

pong.py

# Copyright (c) 2018 Peter Kwak (Edited by Chris Pedersen)
# This is free and unencumbered software released into the public domain.
# For more information, please refer to <http://unlicense.org/>

import turtle

# Create Game Window 
screen = turtle.Screen()
# screen.setup(500, 400)
screen.screensize(500, 500, "black")
screen.bgcolor("black")
# screen.addshape("Paddle.jpg")

# Create Ping Pong Ball
ball = turtle.Turtle()
ball.penup()
ball.speed(0)
ball.shape("circle")
ball.color("white")

# Create Left Ping Pong Paddle
paddle1 = turtle.Turtle()
paddle1.penup()
paddle1.speed(0)
paddle1.setx(-200)
paddle1.shape("square")
paddle1.shapesize(4.5, 1, 0)
paddle1.fillcolor("white")

# Create Right Ping Pong Paddle
paddle2 = turtle.Turtle()
paddle2.penup()
paddle2.speed(0)
paddle2.setx(200)
paddle2.shape("square")
paddle2.shapesize(4.5, 1, 0)
paddle2.fillcolor("white")

# Create Scoreboard
scoreWriter = turtle.Turtle() 
scoreWriter.penup()
scoreWriter.speed(0)
scoreWriter.hideturtle()
scoreWriter.color("white")

# Set Ball Trajectory
rise = 3
run = 3

# Set Score
score1 = 0
score2 = 0

# Create Function Which Will Move Player 1's Paddle Up
def up1():
  paddle1.sety(paddle1.ycor() + 50)

# Create Function Which Will Move Player 1's Paddle Down
def down1():
  paddle1.sety(paddle1.ycor() - 50)

# Create Function Which Will Move Player 2's Paddle Up
def up2():
  paddle2.sety(paddle2.ycor() + 50)

# Create Function Which Will Move Player 2's Paddle Down
def down2():
  paddle2.sety(paddle2.ycor() - 50)
  
# Create Function To Update Scoreboard
def updateScoreboard():
  global scoreWriter
  global score1
  global score2
  global ball
  scoreWriter.clear()
  myFont = ("Arial", 40, "bold")
  scoreWriter.goto(-100, 150)
  scoreWriter.write(score1, font=myFont)
  scoreWriter.goto(100, 150)
  scoreWriter.write(score2, font=myFont)
  ball.goto(0, 0)
  
# Set Event Listeners
# These event listeners will listen for button presses (up, down, etc.)
screen.onkey(up1, "w")
screen.onkey(down1, "s")
screen.onkey(up2, "Up")
screen.onkey(down2, "Down")
screen.listen()

# Create Main Game Loop (Simulates Time, Keeps Game Running)
while True:
  # Move Ball
  ball.goto(ball.xcor() + run, ball.ycor() + rise)
  
  # Detect Top or Bottom Boundary Strike 
  # (Reverses the Ball's Direction of Travel)
  if ball.ycor() > 200 or ball.ycor() < -200:
    rise = -rise
    
  # Detect Paddle Strike (Player 1)
  # (Also Reverses the Ball's Direction of Travel)
  if abs(paddle1.xcor() - ball.xcor()) < 15:
    if abs(paddle1.ycor() - ball.ycor()) < 50:
      run = -run
      
  # Detect Paddle Strike (Player 2)
  # (Also Reverses the Ball's Direction of Travel)
  if abs(paddle2.xcor() - ball.xcor()) < 15:
    if abs(paddle2.ycor() - ball.ycor()) < 50:
      run = -run
    
  # Detect When A Player Scores a Point
  if ball.xcor() > 250:
    # Increment player1's score by 1 point when his ball
    # travels past the paddle of his opponent, player 2.
    score1 = score1 + 1 
    updateScoreboard()
    ball.goto(0, 0)
  elif ball.xcor() < -250:
    # Increment player2's score by 1 point when his ball
    # travels past the paddle of his opponent, player 1.
    score2 = score2 + 1 
    updateScoreboard()
    ball.goto(0, 0)
    
  # Christine, My Super Sweet AI Goes HERE...
  if ball.ycor() > paddle2.ycor() + 25:
    paddle2.sety(paddle2.ycor() + 15)
  elif ball.ycor() < paddle2.ycor() - 25:
    paddle2.sety(paddle2.ycor() - 15)