… performance is … disappointing. I just remembered why
I used to like writing against DirectDraw. It seems Windows users
are simply destined to get better gaming experience; currently my
engine manages about 15 fps under SDL/x11, whereas the original
(straight DirectDraw/Input) version easily managed 80-90 fps. !
Have you actually tried the engine under SDL/DirectX? You should get
similar performance to what you expect.
Nope, I haven’t because of the link problem I mentioned. But 0.6g
just flew down the line, so I’ll by trying that in a moment.
Tips for speed under SDL:
A. Set the SDL_HWSURFACE flag on SDL_SetVideoMode() – UNLESS you are
going to be directly writing to the surface pixels, in which case
most newer video cards are faster using SDL_SWSURFACE and accelerated
B. Make sure you set a high-speed video mode. SDL_GetVideoMode() is
a very useful function.
Hm… I sort of “know” that I need 640x480x8; is there any point in
"looking" for that mode? Now I just set it and let that be the end of
C. Convert all your artwork to the surface format of the display surface.
If you are using SDL surfaces, use SDL_DisplayFormat() to convert them.
I always do.
B. Set the SDL_RLEACCEL flag in colorkeyed blits. This is a huge speedup
when doing colorkeying on software surfaces.
I do that, too. Can it ever cause surfaces not to be blitted by the
hardware, if they are HWSURFACEs?
C. Don’t use alpha blending every frame - it’s cool, but slow.
I never use it. Pure color keying is enough right now…
D. Update only those areas which have actually changed. Important!
Arg. That’s the one I can’t comply to. My app uses full-screen
scrolling, and thus rebuilds the entire screen from scratch every
There is however one method of X11 setup that I don’t currently use:
XFree86 Direct Graphics Access
With this, you shove the X Server aside and directly access the display
video memory. You still don’t get hardware acceleration (last I heard)
but you get to scribble all over video memory to your heart’s content.
Unfortunately, your app requires root priviledges.
Yeah, I’ve seen some DGA programs around. It’s fairly cool, but as
you say wouldn’t gain much in raw performance. It’s nice to be able
to switch to a lower resolution, though (I generally think games gain
from being run full-screen).
/EmilOn Fri, 17 Apr 1998, Sam Lantinga wrote: