hi,

perhaps it is a video card surface in full screen mode.  Unfortunately
reading data from the video card is a bit slow.

With no hardware alpha, it is going to go slowly.  As alpha blitting
needs to read the pixels in order to blend them.


On 5/20/06, Nelson, Scott <SNelson@[...].com>  wrote:
> 
> 
> 
> 
>  I've been messing with pygame for awhile and am having a blast!  Thanks for
>  a great site, pygame.org people!  And, I just got on this list and already
>  its been very helpful!
> 
> 
> 
>  I ran into a performance snag trying to blit a surface with surface-alpha to
>  a fullscreen display surface (trying to do a fade-to-black for the screen).
>  It works great (realtime) when the display is windowed.  Lotsa fun!  But,
>  when the display is fullscreen, each blit takes almost a second to complete
>  in 640x480 on a beefy machine.
> 
> 
> 
>  Now, I've read the pygame docs on surfaces and displays and searched this
>  list (finding some related discussions) and can't quite nail down what my
>  problem is.
> 
> 
> 
>  So, my question is: why does it take me so long to blit in fullscreen mode?
>  And, how can I create the surfaces in such a way that the blit performs at
>  realtime in both windowed and fullscreen mode?
> 
> 
> 
>  Here's some snatches of my code.  I grabbed the important bits, as it would
>  be too much code to post all my classes in their entirety.
> 
> 
> 
>  â?¦Set up windowed mode:
> 
> 
> 
>  pygame.display.set_mode((640, 480))
> 
> 
> 
>  ...or set up fullscreen mode:
> 
> 
> 
>  pygame.display.set_mode((640, 480), pygame.FULLSCREEN | pygame.HWSURFACE)
> 
> 
> 
>  ...creating the surface to do the fade:
> 
> 
> 
>  self._fadeSurface = pygame.Surface(size)
> 
>  self._fadeSurface.fill(color)
> 
>  self._fadeSurface.set_alpha(alpha)
> 
>  self._fadeSurface = self._fadeSurface.convert()
> 
> 
> 
>  ...blitting the fade surface to the display:
> 
> 
> 
>  self._targetSurface.blit(self._fadeSurface, (0, 0))
> 
> 
> 
>  In windowed mode, pygame.display.Info() returns:
> 
> 
> 
>  <VideoInfo(hw = 1, wm = 1,video_mem = 238032
> 
>               blit_hw = 1, blit_hw_CC = 1, blit_hw_A = 0,
> 
>               blit_sw = 1, blit_sw_CC = 1, blit_sw_A = 0,
> 
>               bitsize  = 32, bytesize = 4,
> 
>               masks =  (16711680, 65280, 255, 0),
> 
>               shifts = (16, 8, 0, 0),
> 
>               losses =  (0, 0, 0, 8)>
> 
> 
> 
>  In fullscreen mode, pygame.display.Info() returns:
> 
> 
> 
>  <VideoInfo(hw = 1, wm = 1,video_mem = 244688
> 
>               blit_hw = 1, blit_hw_CC = 1, blit_hw_A = 0,
> 
>               blit_sw = 1, blit_sw_CC = 1, blit_sw_A = 0,
> 
>               bitsize  = 32, bytesize = 4,
> 
>               masks =  (16711680, 65280, 255, 0),
> 
>               shifts = (16, 8, 0, 0),
> 
>               losses =  (0, 0, 0, 8)>
> 
> 
> 
>  So, the alpha HW acceleration capabilities of the display in either mode are
>  the same.  I do a convert() on the surface before blitting so it's format
>  should match the display's.  Why is the blit so slow in one case (fullscreen
>  surface) and realtime in the other (windowed surface)?  I'm sure this has
>  something to do with mismatches in surface modes, but I haven't been able to
>  get a handle on the details.
> 
> 
> 
>  Thanks in advance...
> 
> 
> 
>  -Scott
> 
>