Notes

import pygame, sys
from pygame.locals import *

# Number of frames per second
# Change this value to speed up or slow down your game
FPS = 200

#Global Variables to be used through our program

WINDOWWIDTH = 400
WINDOWHEIGHT = 300
LINETHICKNESS = 10
PADDLESIZE = 50
PADDLEOFFSET = 20

# Set up the colours
BLACK = (0 ,0 ,0 )
WHITE = (255,255,255)

#Draws the arena the game will be played in.
def drawArena():
DISPLAYSURF.fill((0,0,0))
#Draw outline of arena
pygame.draw.rect(DISPLAYSURF, WHITE, ((0,0),(WINDOWWIDTH,WINDOWHEIGHT)), LINETHICKNESS*2)
#Draw centre line
pygame.draw.line(DISPLAYSURF, WHITE, ((WINDOWWIDTH/2),0),((WINDOWWIDTH/2),WINDOWHEIGHT), (LINETHICKNESS/4))


#Draws the paddle
def drawPaddle(paddle):
#Stops paddle moving too low
if paddle.bottom > WINDOWHEIGHT - LINETHICKNESS:
paddle.bottom = WINDOWHEIGHT - LINETHICKNESS
#Stops paddle moving too high
elif paddle.top < LINETHICKNESS:
paddle.top = LINETHICKNESS
#Draws paddle
pygame.draw.rect(DISPLAYSURF, WHITE, paddle)


#draws the ball
def drawBall(ball):
pygame.draw.rect(DISPLAYSURF, WHITE, ball)

#moves the ball returns new position
def moveBall(ball, ballDirX, ballDirY):
ball.x += ballDirX
ball.y += ballDirY
return ball

#Checks for a collision with a wall, and 'bounces' ball off it.
#Returns new direction
def checkEdgeCollision(ball, ballDirX, ballDirY):
if ball.top == (LINETHICKNESS) or ball.bottom == (WINDOWHEIGHT - LINETHICKNESS):
ballDirY = ballDirY * -1
if ball.left == (LINETHICKNESS) or ball.right == (WINDOWWIDTH - LINETHICKNESS):
ballDirX = ballDirX * -1
return ballDirX, ballDirY

#Checks is the ball has hit a paddle, and 'bounces' ball off it.
def checkHitBall(ball, paddle1, paddle2, ballDirX):
if ballDirX == -1 and paddle1.right == ball.left and paddle1.top < ball.top and paddle1.bottom > ball.bottom:
return -1
elif ballDirX == 1 and paddle2.left == ball.right and paddle2.top < ball.top and paddle2.bottom > ball.bottom:
return -1
else: return 1

#Checks to see if a point has been scored returns new score
def checkPointScored(paddle1, ball, score, ballDirX):
#reset points if left wall is hit
if ball.left == LINETHICKNESS:
return 0
#1 point for hitting the ball
elif ballDirX == -1 and paddle1.right == ball.left and paddle1.top < ball.top and paddle1.bottom > ball.bottom:
score += 1
return score
#5 points for beating the other paddle
elif ball.right == WINDOWWIDTH - LINETHICKNESS:
score += 5
return score
#if no points scored, return score unchanged
else: return score

#Artificial Intelligence of computer player
def artificialIntelligence(ball, ballDirX, paddle2):
#If ball is moving away from paddle, center bat
if ballDirX == -1:
if paddle2.centery < (WINDOWHEIGHT/2):
paddle2.y += 1
elif paddle2.centery > (WINDOWHEIGHT/2):
paddle2.y -= 1
#if ball moving towards bat, track its movement.
elif ballDirX == 1:
if paddle2.centery < ball.centery:
paddle2.y += 1
else:
paddle2.y -=1
return paddle2

#Displays the current score on the screen
def displayScore(score):
resultSurf = BASICFONT.render('Score = %s' %(score), True, WHITE)
resultRect = resultSurf.get_rect()
resultRect.topleft = (WINDOWWIDTH - 150, 25)
DISPLAYSURF.blit(resultSurf, resultRect)

#Main function
def main():
pygame.init()
global DISPLAYSURF
##Font information
global BASICFONT, BASICFONTSIZE
BASICFONTSIZE = 20
BASICFONT = pygame.font.Font('freesansbold.ttf', BASICFONTSIZE)

FPSCLOCK = pygame.time.Clock()
DISPLAYSURF = pygame.display.set_mode((WINDOWWIDTH,WINDOWHEIGHT))
pygame.display.set_caption('Pong')

#Initiate variable and set starting positions
#any future changes made within rectangles
ballX = WINDOWWIDTH/2 - LINETHICKNESS/2
ballY = WINDOWHEIGHT/2 - LINETHICKNESS/2
playerOnePosition = (WINDOWHEIGHT - PADDLESIZE) /2
playerTwoPosition = (WINDOWHEIGHT - PADDLESIZE) /2
score = 0

#Keeps track of ball direction
ballDirX = -1 ## -1 = left 1 = right
ballDirY = -1 ## -1 = up 1 = down

#Creates Rectangles for ball and paddles.
paddle1 = pygame.Rect(PADDLEOFFSET,playerOnePosition, LINETHICKNESS,PADDLESIZE)
paddle2 = pygame.Rect(WINDOWWIDTH - PADDLEOFFSET - LINETHICKNESS, playerTwoPosition, LINETHICKNESS,PADDLESIZE)
ball = pygame.Rect(ballX, ballY, LINETHICKNESS, LINETHICKNESS)

#Draws the starting position of the Arena
drawArena()
drawPaddle(paddle1)
drawPaddle(paddle2)
drawBall(ball)

pygame.mouse.set_visible(0) # make cursor invisible

while True: #main game loop
for event in pygame.event.get():
if event.type == QUIT:
pygame.quit()
sys.exit()
# mouse movement commands
elif event.type == MOUSEMOTION:
mousex, mousey = event.pos
paddle1.y = mousey

drawArena()
drawPaddle(paddle1)
drawPaddle(paddle2)
drawBall(ball)

ball = moveBall(ball, ballDirX, ballDirY)
ballDirX, ballDirY = checkEdgeCollision(ball, ballDirX, ballDirY)
score = checkPointScored(paddle1, ball, score, ballDirX)
ballDirX = ballDirX * checkHitBall(ball, paddle1, paddle2, ballDirX)
paddle2 = artificialIntelligence (ball, ballDirX, paddle2)

displayScore(score)

pygame.display.update()
FPSCLOCK.tick(FPS)

if __name__=='__main__':
main()