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Re: [pygame] Blitting image with alpha channel on a transparent background

yeah, that worked for me, here's my (messy) example code:

import pygame
from pygame.locals import *
import os

pygame.init()

screen = pygame.display.set_mode((100,100))
screen.fill([0, 0, 0]) # blank the screen.

#random image
fartherback = pygame.image.load(os.path.join("Images", "Blocks.png")).convert_alpha() 

#equivalent to the background in your example
notasfar = pygame.Surface((100,100)).convert_alpha()
notasfar.fill((0,0,0,50))

#another random image
image = pygame.image.load(os.path.join("Images", "girl-walking-down.png")).convert_alpha()

while True:
    screen.blit(fartherback.subsurface((0,0),(100,100)), (0, 0, 100, 100))
    screen.blit(notasfar, (0,0,100,100))
    screen.blit(image, (0,0,64,64))

    pygame.display.update()
    pygame.time.wait(200)





On Thu, Apr 22, 2010 at 2:12 PM, Lee Buckingham <lee.buckingham@xxxxxxxxx> wrote:
Instead of using set_alpha(), try using a fill, like:

 backgroundsurface.fill((0,0,0,100))

that should make the background use per-pixel alpha too, since there's a fourth number in the color (for alpha) so blitting another per-pixel alpha image shouldn't cause problems.   Hmm... maybe I'll try it out too.

-Lee-




On Thu, Apr 22, 2010 at 12:46 PM, stas zytkiewicz <stas.zytkiewicz@xxxxxxxxx> wrote:
On Thu, Apr 22, 2010 at 6:56 PM, Lee Buckingham
<lee.buckingham@xxxxxxxxx> wrote:

> As far as the alpha goes, my guess is that you're getting hung up because
> you've mixed two different alpha modes.  There's some caveats about using
> per-pixel alpha (like the .png file probably has) and the other modes (color
> key or single value alpha like you've got).
That's my guess to and as I'm no alpha stuff expert I turned to this list.

> So i'd first try just eliminating the transparency on the background, if in
> fact there's nothing behind it anyway.
I want to create a semi transparent GUI button with a solid image or text
so transparency of the background is the whole purpose :-)