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Re: X11 speed (was Re: Interested in starting some basic development)

Borko Jandras wrote:

> On Thu, Nov 19, 1998 at 08:31:32AM +0100, Jorrit Tyberghein wrote:
> > > X? I did a very simple test. Opened up a 640x480 window and drawed a rectangle
> > > across it, using Mesa. It took cca. 150 milliseconds for each frame.
> > > Let me spare you the calculation, that's 6.6 fps. Can you live with that?
> > > Oh yes, the machine was K6-2 333. X just isn't made for such things.
> >
> > Crystal Space (yes that ugly C++ library of mine :-) runs with the following
> > speeds in X with a 640x480 window (16-bit display mode):
> >     My old pentium 90: 10 FPS
> >     My new P-II 400: 27 FPS
> >
> > And you have to keep in mind that it also has to do some rendering instead
> > of only blitting to the screen.
> Thit is better than what I get, but is still not enough. I don't know what kind
> of rendering CS does, but I would expect 10 fps on 486DX2-66.

Really? CS renders similarly to the Quake engine and Quake did not get those
speeds at all.

With the above speed numbers CS has to do:
    - Visibility determination of polygons in a world and clipping.
    - Full-screen perpective correct texture mapping.

Note that when I just blit the screen and don't do any rendering at all
I got speeds on my P-II 400 of about 350FPS (in X windows!).
I think that should be enough for most games :-)

> > You just have to use the SHM extension (shared memory extension).
> > This helps a VERY GREAT deal. With that extension you get almost the
> > same speeds as with svgalib but without the suid problems.
> I'm using SHM, that is Mesa is using it. Why is it so crappy then? How am I to
> make a decent game for Linux if you need K6-2 to play it.

Maybe it is Mesa that is causing the slow-down?


Jorrit.Tyberghein@uz.kuleuven.ac.be, University Hospitals KU Leuven BELGIUM

The shortest unit of time in the multiverse is the New York Second, defined
as the period of time between the traffic lights turning green and the cab
behind you honking.
        -- (Terry Pratchett, Lords and Ladies)