Re: [pygame] Simple Surfarray Alpha

[Lenard Lindstrom <len-l@xxxxxxxxx>]

Hi Ian,

There's not enough information to make a diagnosis. What was the error? 
Are you sure the surface has per-pixel alpha? What array package are you 
using? With  NumPy and the latest Pygame I get no error:

>>> import pygame as pg
>>> s = pg.Surface((10,10), pg.SRCALPHA, 32)
>>> a = pg.surfarray.pixels_alpha(s)
>>> a[:,:] = 255 - a[:,:]
>>> del a
>>> s.get_at((0,0))
(0, 0, 0, 255)

Lenard


Ian Mallett wrote:
> Hello,
>
> I need to make a function where the alpha value of a surface is 
> flipped.  I can already do this with the red, green, or blue channels:
>
> #red flip
> array = pygame.surfarray.pixels3d(surface)
> array[:,:,0] = 255-array[:,:,0]
> del array
>
> #green flip
> array = pygame.surfarray.pixels3d(surface)
> array[:,:,1] = 255-array[:,:,1]
> del array
>
> #blue flip
> array = pygame.surfarray.pixels3d(surface)
> array[:,:,2] = 255-array[:,:,2]
> del array
>
> #rgb flip
> array = pygame.surfarray.pixels3d(surface)
> array[:,:,:] = 255-array[:,:,:]
> del array
>
> I can't do the alpha flip though.  I tried:
>
> array = pygame.surfarray.pixels_alpha(surface)
> array[:,:] = 255-array[:,:]
> del array
>
> but it raises an error.
>
> Ideas?
> Thanks,
> Ian


--
Lenard Lindstrom
<len-l@xxxxxxxxx>