pygame.display.update()
red = pygame.Surface((200, 100))
red.fill(RED)
green = pygame.Surface((100, 100), 0)
green.fill(GREEN)
for a in range(700):
    blit_mask(text, windowSurface, (a, 0), green, (0, 0, 800, 600))
while True:
    for event in pygame.event.get():
        if event.type == QUIT:
            pygame.quit()
sys.exit()
Pygame: How to draw in non rectangle clipping area