Blinking of 2 circles

Question

I have to blink(on and off) 2 circles alternatively using pygame. How to make it blink using pygame.

for event in pygame.event.get():
    blueball = pygame.draw.circle(screen, b, (175,100),20,3)
    redball = pygame.draw.circle(screen, r, (675,350),20,3)
    if event.type == pygame.KEYDOWN:
        if event.key == pygame.K_UP:
            bluebally += 5
            redballx +=5
        if event.key == pygame.K_DOWN:
            bluebally += 5
            redballx +=5
        if event.key == pygame.K_RIGHT:
            blueballx += 5
            redbally +=5
        if event.key == pygame.K_RIGHT:
            blueballx += 5
            redbally +=5
    if event.type == pygame.QUIT:
        pygame.quit()
        sys.exit()
    screen.blit(blueball,(blueballx,bluebally))
    screen.blit(redball,(redballx,redbally))

I expect blue ball and redball blink alternatively

What part of this code should make it blink? `blit` means `draw`, not `blink`. You can use some index (`color_cycle_index`) and increase it every second (`color_cycle_index += 1`) and blit/draw blue if even (`color_cycle_index % 2 == 0`) and draw red otherwise. — Laurens Koppenol, Aug 12 '19 at 09:16
Thank you, I am new to programming and pygame. I just asked the question with whatever I tried using the tutorials. However, i didnt get how to blink a circle. My output should be red and blue ball blinking alternatively. — kalingabhat, Aug 12 '19 at 09:27
With blinking you mean 1 circle which alternates between red / blue or 2 circles which both blink but not simultanuously? — Laurens Koppenol, Aug 12 '19 at 09:40

Laurens Koppenol · Accepted Answer · 2019-08-12T10:04:33.057

0

I don't know your full code, but let me know if this helps you:

Somewhere before the drawing function

color_cycle_index = 0

Then in your drawing function

if event.type == pygame.KEYDOWN:
    if event.key == pygame.K_UP:
        bluebally += 5
        redballx +=5
    if event.key == pygame.K_DOWN:
        bluebally += 5
        redballx +=5
    if event.key == pygame.K_RIGHT:
        blueballx += 5
        redbally +=5
    if event.key == pygame.K_RIGHT:
        blueballx += 5
        redbally +=5
if event.type == pygame.QUIT:
    pygame.quit()
    sys.exit()

if color_cycle_index % 2 == 0:
    # draw red
    pygame.draw.circle(screen, r, (redballx, redbally), 20, 3)
else:
    # draw blue
    pygame.draw.circle(screen, b, (blueballx, bluebally), 20, 3)

color_cycle_index += 1  # <-- it's better to increase this every n seconds instead of every frame

edited Aug 12 '19 at 10:04

answered Aug 12 '19 at 09:43

Laurens Koppenol

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Thank you for your time. I tried with this and ended up with an error saying ```argument 1 must be pygame.Surface, not pygame.Rect``` – kalingabhat Aug 12 '19 at 09:51
on what function? – Laurens Koppenol Aug 12 '19 at 09:55
Error saying ```screen.blit(redball, (redballx, redbally)) TypeError: argument 1 must be pygame.Surface, not pygame.Rect``` – kalingabhat Aug 12 '19 at 10:02
just remove the blit lines, see updated answer. I suppose you already had this error before? – Laurens Koppenol Aug 12 '19 at 10:05
Read this about blit: https://stackoverflow.com/questions/17454257/a-bit-confused-with-blitting-pygame – Laurens Koppenol Aug 12 '19 at 10:06
1

I found that article useful. And as you suggested, removing blit lines helped me to achieve this and also found out that ```K_UP K_DOWN``` commands were not usefull for this. Thank You. – kalingabhat Aug 13 '19 at 12:23

Blinking of 2 circles

1 Answers1