#MonthOfCode day 20 - play

day_20.py

import random
import pygame
from pygame.locals import *
SCREEN_W = 640
SCREEN_H = 480

def refeshFunction():
    DISPLAYSURF.fill(  pygame.Color('antiquewhite3') )
    # draws the paddle
    rect_rep_paddle =\
         pygame.Rect( (pos_x_paddle-(PADDLE_X_SIZE/2), pos_y_paddle),
         (PADDLE_X_SIZE, PADDLE_Y_SIZE)) # format: (left,top) , (width,height)
    pygame.draw.rect( DISPLAYSURF, pygame.Color('black'), rect_rep_paddle )
    # draws the ball
    pygame.draw.circle( DISPLAYSURF, pygame.Color('black'),
        (ball_x, ball_y), BALL_RAD  )
    pygame.display.update() 

# init. pygame libr; create the screen 
pygame.init() 
DISPLAYSURF = pygame.display.set_mode( (SCREEN_W,  SCREEN_H))

PADDLE_X_SIZE, PADDLE_Y_SIZE = 128, 32
BALL_RAD = 16

started_playing= False
ball_x = pos_x_paddle = SCREEN_W/2
ball_y = pos_y_paddle = SCREEN_H - 2*PADDLE_Y_SIZE
ball_y -= BALL_RAD
program_done = False

ball_delay = 11
counter = 0
#main loop
while not program_done:
    for event in pygame.event.get():
        if event.type == QUIT:
            program_done = True
            break
        if event.type == pygame.MOUSEMOTION:
            pos_x_paddle = pygame.mouse.get_pos()[0]
            #blocking the paddle if it gets out of the screen
            if( pos_x_paddle-(PADDLE_X_SIZE/2) <0):
                pos_x_paddle = (PADDLE_X_SIZE/2) 
            if (pos_x_paddle+(PADDLE_X_SIZE/2)>=SCREEN_W):
                pos_x_paddle=SCREEN_W -(PADDLE_X_SIZE/2)-1
            #copying the new position to the ball if not playing yet
            if(not started_playing):
                ball_x = pos_x_paddle
        if event.type == pygame.MOUSEBUTTONDOWN :
            if not started_playing:
                started_playing = True
                vx,vy = 2, -2  
    # physics of the ball
    if(started_playing and counter==0 ): 
        ball_x+=vx
        ball_y+=vy 
        if(ball_x-BALL_RAD<0):
            ball_x=0+BALL_RAD
            vx*=-1
        if(ball_x+BALL_RAD>=SCREEN_W):
            ball_x=SCREEN_W-BALL_RAD-1
            vx*=-1
        if(ball_y-BALL_RAD<0):
            ball_y=0+BALL_RAD
            vy*=-1
        if(ball_y+BALL_RAD>=SCREEN_H):
            ball_y=SCREEN_H-BALL_RAD-1
            vy*=-1
        if(ball_y > pos_y_paddle-(PADDLE_Y_SIZE/2) and
            ball_x > pos_x_paddle-(PADDLE_X_SIZE/2) and
            ball_x < pos_x_paddle+(PADDLE_X_SIZE/2) ):
            vy*=-1
            #accelerating the ball on every good hit
            ball_delay-=1
            if(ball_delay<3):
                ball_delay=3
    counter+=1
    counter=counter%ball_delay #we move the ball only every ball_delay iterations
    refeshFunction()

pygame.quit()