Conference Freed.in 2009

Presentor: O.R.Senthil Kumaran <senthil@uthcode.com>

Presentation Source at http://www.uthcode.com

• Curiousity.

• Game Development.

• Python Basics.

• Let us have a pygame window to put some text in it.

• Our first the pygame window.

# Complete Program.

import pygame

WINDOW = WIDTH, HEIGHT = 400, 300

def main():
    pygame.init()
    screen = pygame.display.set_mode(WINDOW)

if __name__ == '__main__':
    main()

• Truely so. Because we did not ask it to stay.

• In pygame, While True: pygame.display.flip() plays a major role in continously displaying the screen and making the image to stay.

• Additionally, we can set the window title using set_caption.

# Complete Program.

import pygame

WINDOW = WIDTH, HEIGHT = 400, 300

def main():
    pygame.init()
    screen = pygame.display.set_mode(WINDOW)
    pygame.display.set_caption("Freed.in Demo")

    while True:
        pygame.display.flip()

if __name__ == '__main__':
    main()

• Normal text wont do, you have to instantiate a Font() object and Render your text.

• Display (Blit) your text at the position, continuosuly.

import pygame
...
GREY = (210,210,210)

def main():
    ...
    font = pygame.font.Font(None, 42)
    text = font.render("Freed.in Rocks!",1,GREY)
    textrect = text.get_rect()

    while True:
        screen.blit(text,textrect)
        pygame.display.flip()

• Keys are got from pygame.event.get()

• Verify if the pygame.QUIT key is received.

import pygame
import sys
...
def main():
    ...
    textrect = text.get_rect()
    ...
    while True:
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                sys.exit()

        screen.blit(text,textrect)
        pygame.display.flip()

• Let us move the text.

• In pygame, you move the textrect to different position.

import pygame
...
MOVE = [0,1]  # X Direction, Y Direction.

def main():
    pygame.init()
    ...
    while True:
        ...
        screen.blit(text,textrect)
        textrect = textrect.move(MOVE)
        pygame.display.flip()

• Because, we did not blit it with BLACK Background again.

import pygame
...
BLACK = (0,0,0)
GREY = (210,210,210)
MOVE = [0,1]  # X Direction, Y Direction.

def main():
    pygame.init()
    ...
    while True:
        ...
        textrect = textrect.move(MOVE)

        screen.fill(BLACK)
        screen.blit(text,textrect)
        textrect = textrect.move(MOVE)
        pygame.display.flip()

• We had not added any logic or control to move.

• Let us move it till it reaches the bottom of the screen and then move it back up.

import pygame
...
MOVE = [0,1]  # Y Direction, X Direction.

def main():
    pygame.init()
    ...
    while True:
        ...
        textrect = textrect.move(MOVE)

        if textrect.top < 0 or textrect.bottom > HEIGHT:
            MOVE[1] = -MOVE[1]  # Move in the opposite Direction.

        screen.fill(BLACK)
        screen.blit(text,textrect)

import pygame
...
MOVE = [1,0]  # Y Direction, X Direction.

def main():
    pygame.init()
    ...
    while True:
        ...
        textrect = textrect.move(MOVE)

        if textrect.left < 0 or textrect.right > WIDTH:
            MOVE[0] = -MOVE[0]  # Move in the opposite Direction.
        ...
    ...

import pygame
...
MOVE = [1,1]  # Y Direction, X Direction.

def main():
    pygame.init()
    ...
    while True:
        ...
        if textrect.left < 0 or textrect.right > WIDTH:
            MOVE[0] = -MOVE[0]  # Move ACROSS in the opposite Direction.
        if textrect.top < 0 or textrect.bottom > HEIGHT:
            MOVE[1] = -MOVE[1]  # Move Horizontally in opp Direction.

        screen.fill(BLACK)
        screen.blit(text,textrect)

• So, we see that Freed.in really Rocks!

import pygame
import sys

SIZE = WIDTH, HEIGHT = 398,390

def main():
    pygame.init()
    pygame.display.set_caption("Escher")
    screen = pygame.display.set_mode(SIZE)

    picture = pygame.image.load('Drawing-hands.jpg').convert()
    picturerect = picture.get_rect()

    while True:
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                sys.exit()
        screen.blit(picture, picturerect)
        pygame.display.flip()

if __name__ == '__main__':
    main()

• Minimal. Dont you agree?

• After the image.load class, it is basically a rectangle of pixels.

• And you operate with those colored rectangles.

• So, instead of the Text movement, can your image move? Ofcourse, Why not?

• Tutorial-1

• Tutorial-2

• Tutorial-3