I have been experimenting with GL and RTLinux for over a year. I am
currently testing with a dual 850mhz PIII box and a NVIDIA Ge3 card. I have
installed and built Xfree86 4.1.0 and the latest NVIDIA reference drivers
1.0-1251. I have been running a level C flight simulator at 30hz (but with
periodic scheduler at 60hz) under NMT 3.0 patched into 2.4.5. - And a GL
based real-world terrain generation system simultaneously. The worst jitter
I have seen (observed over months of testing) has been in the 80 to 100usec
range. This kind of jitter is insignificant as far as my 60hz simulation
task is concerned. Till now I have assumed most of this jitter was due to
cache misses and bus delays (large amounts of video data ARE being
transferred to and fro). It is however possible that the NVIDIA drivers may
be disabling interrupts for short periods of time. Still my GL app is able
to generate 1024x768 images with 4x4 anti-aliasing at >= 120 FPS with the
above mentioned jitter. More than adequate for a baseline flightsim/visual
combo in the same LINUX box.
Has anyone else had similar (positive) results/experience with X and GL?
Todd Gearheart
Software Engineer Dept 041
FlightSafety International
Simulation Systems Division
[EMAIL PROTECTED]
(316) 612-5356
-----Original Message-----
From: David Olofson [mailto:[EMAIL PROTECTED]]
Sent: Thursday, August 23, 2001 12:20 PM
To: [EMAIL PROTECTED]
Subject: Re: [rtl] user space program hangs
On Thursday 23 August 2001 17:07, Dan Peters wrote:
> David Olofson wrote:
> > On Wednesday 22 August 2001 10:10, Stephane List wrote:
[...]
> > > Why don't try OpenGL too for 3D graphism; ;-)
> >
> > You can use SDL to set up the OpenGL screen in a clean and portable
> > way. (Far better than GLUT in pretty much every respect.) However,
> > there's a pretty limited choice of accelerated OpenGL drivers for
> > non-X targets.
>
> I really do not need any special 3d graphics, so I think GL is a bit
> overkill.
> basically, all I need is a few windows to display some temperature
> data, and another window to display image data, all in real time.
Should work great.
> > > The best way is to have a realtime PC without X, and to connect to
> > > it with an other PC through ssh for example.
>
> this is not pratical for my implementation. The whole thing must reside
> on an embedded PC, which sits inside the control unit.
That means you have full control over what drivers are used, which makes
things even easier. You can just code for SDL and the try svgalib, fbdev
and raw X with DGA 2 and see what works best for you. You don't have to
support multiple pixel formats (ie 8, 15, 16, 24 and 32 bits/pixel)
either, as you can dictate the choice of hardware and driver settings.
//David Olofson --- Programmer, Reologica Instruments AB
.- M A I A -------------------------------------------------.
| Multimedia Application Integration Architecture |
| A Free/Open Source Plugin API for Professional Multimedia |
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.- David Olofson -------------------------------------------.
| Audio Hacker - Open Source Advocate - Singer - Songwriter |
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