Lesson #3 - The Moving Square

Lesson number three teaches movement in the Y axis.

The main concepts:

• Add 1 to the y axis to move down;
• Subtract 1 to the y axis to move up;
• Bounds checking to detect when the square reaches the edge of the screen;
• Conditional to change direction;
• Clock to set the maximum Frames Per Second (FPS) that the game runs at

import pygame, sys pygame.init() FPS = 30 clock = pygame.time.Clock() size = (480, 320) screen = pygame.display.set_mode(size) # define color using Red, Green, Blue values # 0 is blank # 255 is maximum RED = (255, 0, 0) # all red. no other color BLACK = (0, 0, 0) # left edge of rectangle, top, width height player_rect = pygame.Rect(0, 0, 64, 64) direction = "down" while True: for event in pygame.event.get(): if event.type == pygame.QUIT: pygame.quit() sys.exit() screen.fill(BLACK) pygame.draw.rect(screen, RED, player_rect) if direction == "down": player_rect.centery += 1 elif direction == "up": player_rect.centery -= 1 if player_rect.bottom > size[1]: direction = "up" if player_rect.top < 0: direction = "down" clock.tick(FPS) pygame.display.update()