Pong_game.py

# Implementation of classic arcade game Pong

import simplegui
import random

# initialize globals - pos and vel encode vertical info for paddles
WIDTH = 600
HEIGHT = 400       
BALL_RADIUS = 20
PAD_WIDTH = 8
PAD_HEIGHT = 80
HALF_PAD_WIDTH = PAD_WIDTH / 2
HALF_PAD_HEIGHT = PAD_HEIGHT / 2
LEFT = False
RIGHT = True




# initialize ball_pos and ball_vel for new bal in middle of table
# if direction is RIGHT, the ball's velocity is upper right, else upper left
def spawn_ball(direction):
    global ball_pos, ball_vel # these are vectors stored as lists
    ball_pos = [WIDTH/2, HEIGHT/2]
    ball_vel = [random.randrange(120, 240)/60,random.randrange(60, 180)/60]   
    if direction == RIGHT:    
        ball_vel[0] =  ball_vel[0]
        ball_vel[1] = - ball_vel[1]                 
    if direction == LEFT:
        ball_vel[0] = - ball_vel[0]
        ball_vel[1] = - ball_vel[1]  
     
def new_game():
    global paddle1_pos, paddle2_pos, paddle1_vel, paddle2_vel  # these are numbers
    global score1, score2  # these are int
    paddle1_pos = HEIGHT / 2
    paddle2_pos = HEIGHT / 2
    paddle1_vel = 0
    paddle2_vel = 0
    score1 = 0
    score2 = 0
    spawn_ball(LEFT)
        
# define event handlers
def draw(canvas):
    global score1, score2, paddle1_pos, paddle2_pos, ball_pos, ball_vel
    # draw mid line and gutters
    canvas.draw_line([WIDTH/2, 0],[WIDTH / 2, HEIGHT], 1, "White")
    canvas.draw_line([PAD_WIDTH, 0],[PAD_WIDTH, HEIGHT], 1, "White")
    canvas.draw_line([WIDTH - PAD_WIDTH, 0],[WIDTH - PAD_WIDTH, HEIGHT], 1, "White")
        
    # update ball  
    if ball_pos[0] <= PAD_WIDTH + BALL_RADIUS:
        if ball_pos[1] > paddle1_pos - HALF_PAD_HEIGHT - BALL_RADIUS and ball_pos[1] < paddle1_pos + HALF_PAD_HEIGHT + BALL_RADIUS:
            ball_vel[0] = - ball_vel[0]
            ball_vel[0] *= 1.1
            ball_vel[1] *= 1.1       
        else: 
            spawn_ball(RIGHT)
            score2 += 1
            
    if ball_pos[0] >= WIDTH - PAD_WIDTH - BALL_RADIUS:
        if ball_pos[1] > paddle2_pos - HALF_PAD_HEIGHT - BALL_RADIUS and ball_pos[1] < paddle2_pos + HALF_PAD_HEIGHT + BALL_RADIUS:
            ball_vel[0] = -ball_vel[0]
            ball_vel[0] *= 1.1
            ball_vel[1] *= 1.1    
        else:
            spawn_ball(LEFT)
            score1 += 1
            
    if ball_pos[1] <= BALL_RADIUS:
        ball_vel[1] = -ball_vel[1] 
    if ball_pos[1] >= HEIGHT - BALL_RADIUS:   
        ball_vel[1] = -ball_vel[1] 
        
    ball_pos[0] += ball_vel[0] 
    ball_pos[1] += ball_vel[1]  
       
    # draw ball
    canvas.draw_circle(ball_pos, BALL_RADIUS, 2, "White", "White")
    
    # update paddle's vertical position, keep paddle on the screen 
    if HALF_PAD_HEIGHT <= paddle1_pos + paddle1_vel <= HEIGHT - HALF_PAD_HEIGHT:
        paddle1_pos += paddle1_vel
    if HALF_PAD_HEIGHT <= paddle2_pos + paddle2_vel <= HEIGHT - HALF_PAD_HEIGHT:
        paddle2_pos += paddle2_vel

       

    
    # draw paddles
    canvas.draw_line([HALF_PAD_WIDTH, paddle1_pos-HALF_PAD_HEIGHT],[HALF_PAD_WIDTH, paddle1_pos + HALF_PAD_HEIGHT], PAD_WIDTH, 'yellow')
    canvas.draw_line([WIDTH - HALF_PAD_WIDTH, paddle2_pos-HALF_PAD_HEIGHT],[WIDTH - HALF_PAD_WIDTH, paddle2_pos + HALF_PAD_HEIGHT], PAD_WIDTH, 'yellow')
    
    # determine whether paddle and ball collide


    # draw scores
    canvas.draw_text(str(score1), [250,100],50, "lime")
    canvas.draw_text(str(score2), [350,100],50, "lime")
        
def keydown(key):
    global paddle1_vel, paddle2_vel, paddle1_pos, paddle2_pos
    acc = 4
    if key == simplegui.KEY_MAP["s"]:
        paddle1_vel += acc
    elif key == simplegui.KEY_MAP["down"]:
        paddle2_vel += acc
    elif key == simplegui.KEY_MAP["w"]:
        paddle1_vel -= acc
    elif key == simplegui.KEY_MAP["up"]:
        paddle2_vel -= acc
  

def keyup(key):
    global paddle1_vel, paddle2_vel
    if key == simplegui.KEY_MAP['w'] or key == simplegui.KEY_MAP['s']:
        paddle1_vel = 0
    if (key == simplegui.KEY_MAP['up'] or key == simplegui.KEY_MAP['down']):
        paddle2_vel = 0
        


# create frame
frame = simplegui.create_frame("Pong", WIDTH, HEIGHT)
frame.set_draw_handler(draw)
frame.set_keydown_handler(keydown)
frame.set_keyup_handler(keyup)
frame.add_button('Restart the game', new_game, 200)

# start frame
new_game()
frame.start()