[SDL] Segmentation Fault... please help

thebigcheese thebigcheese at jobybednar.com
Mon Jan 27 00:09:01 PST 2003


Patrick McFarland wrote:

> Its closer to two buffers, and which one is front and back changes on flip.
> (Semantics, yes, I know. But its important to get something like this right.)
> And afaik, software isnt that much slower, but I wouldnt want to be doing
> 640x480x32bit blitting....

Having witnessed the difference between fullscreen doublebuffering in
Win32(hardware) and windowed doublebuffering in Win32(software), I humbly beg to
differ.  There's a difference.  On the order of maxing out the framerate vs getting
35FPS.  The reason is simple...

With hardware acceleration, no blitting at *all* happens during SDL_Flip();  the
video card just changes which memory address it starts scanning from, and SDL swaps
two pointers.  That's pretty well it.  Under software, however, the video card can't
change contexts like that.  You have to blit the entire darn surface over
into video memory before it's displayed.  Under 640*480*32, that means one meg per
frame.  :)  A couple I/O operations and a pointer swap beats a 1MB block transfer in
my book.





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