I have done a patch to eliminate the jitter of 3D-objects near the viewpoint
(for example 3D cockpit objects).
The problem is the roundoff accuracy of the float values used in the
scenegraph together with the transforms of the eyepoint relative to the
scenery center.
The solution will be to move the scenery center near the view point.
This way floats relative accuracy is enough to show a stable picture.
To get that right I have introduced a transform node for the scenegraph which
is responsible for that shift and uses double values as long as possible.
The scenery subsystem now has a list of all those transforms required to place
objects in the world and will tell all those transforms that the scenery
center has changed when the set_scenery_center() of the scenery subsystem is
called.
The problem was not solvable by SGModelPlacement and SGLocation, since not all
objects, especially the scenery, are placed using these classes.
The first approach was to have the scenery center exactly at the eyepoint.
This works well for the cockpit.
But then the ground jitters a bit below the aircraft. With our default views
you can't see that, but that F-18 has a camera view below the left engine
intake with the nose gear and the ground in its field of view, here I could
see that.
Having the scenery center constant will still have this roundoff problems, but
like it is now too, the roundoff error here is exactly the same in each
frame, so you will not notice any jitter.
The real solution is now to keep the scenery center constant as long as it is
in a ball of 30m radius around the view point. If the scenery center is
outside this ball, just put it at the view point.
As a sideeffect of now beeing able to switch the scenery center in the whole
scenegraph with one function call, I was able to remove a one half of a
problem when switching views, where the scenery center was far off for one or
two frames past switching from one view to the next. Also included is a fix
to the other half of this problem, where the view position was not yet copied
into a view when it is switched (at least under glut). This was responsible
for the 'Error: ...' messages of the cloud subsystem when views were
switched.
have a "property" mode as well as the original "binary" mode. The property mode
will allow the remote module to request any set of properties, and it will send
those properties each frame. The remote module can reply with a list of arbitrary
property name/value pairs to update on the FlightGear side.
This is a first stab, so it's not the cleanest, most well concieved code, but it
allows an external module (communicating via a pipe) to have a huge amount of
flexibility in the data in can access and update.
Make SDL window resizable; This exposes the same problem that many
GLUT users have: resizing up may cause a temporary switch to software
rendering if the card is low on memory. Resizing down again switches
back to HW rendering. (KSFO is texture intensive, but there are no
problems in LOWL, and elsewhere.) Less and less users will have the
problem as cards become better, and it's no reason not to allow
resizing altogether.
a safe undersleep() to conserve cpu. Essentially we undersleep our target by
just a bit (to avoid the chance of oversleeping.) Then we finish off the
remaining time slice with a busy-wait loop.
Norman Vine wrote :
> Frederic Bouvier writes:
>
>> Quoting Andy Ross:
>>> * Hopefully in a CPU-friendly way. I know that older versions of
>>> the NVidia drivers did this by spinning in a polling loop
>>> inside the driver. I'm not sure if this has been fixed or not.
>>>
>>> From my experience, the latest non-beta Windows NVidia driver seems to eat CPU
>>
>> even with sync to vblank enabled. The CPU usage is always 100%.
>
> Buried in the PPE sources is a 'hackish' but portable way to limit CPU usage if the desired framerate is met
>
> /*
> Frame Rate Limiter.
>
> This prevents any one 3D window from updating faster than
> about 60Hz. This saves a ton of CPU time on fast machines.
>
> ! I THINK I MUNGED THE VALUE FOR ulMilliSecondSleep() NHV !
> */
>
> static ulClock *ck = NULL ;
>
> if ( frame_rate_limiter )
> {
> if ( ck == NULL )
> {
> ck = new ulClock ;
> ck -> update () ;
> }
>
> int t_ms = (int) ( ck->getDeltaTime() * 1000.0 ) ; /* Convert to ms */
>
> if ( t_ms < 16 )
> ulMilliSecondSleep ( 16 - t_ms ) ;
> }
>
>
I implemented the method pointed out by Norman. It works great on windows and saves me a lot of CPU cycles. This way, I can get the same framerate in moderately populated areas and have CPU idle 50% of the time instead of wildly looping in the NVidia driver while waiting to sync on vblank.
It has been tested on Linux by Melchior. He saw the same gain in CPU cycles.
I have added a --aspect-ratio-multiplier=x.xx option to give some end user
control over the aspect ratio. (This may seem a little strange, but it's a
building block towards the capability of doing asymmetric view frustums in
FlightGear.)
ssgSetNearFar(). This by default creates a symmetric view frustum which is
typically what an application wants.
However, to get control of the view frustum in order to build support for
asymmetric view frustums, we need to wrap these calls with a bit of our own
logic.
This set of changes wraps all calls to ssgSetFOV() and ssgSetNearFar() with
FGRenderer methods.
I also standardized how the FGRenderer class is handled in globals.[ch]xx.
This led to some cascading changes in a variety of source files.
As I was working my way through the changes, I fixed a few warnings along
the way.
I just heard from John Wojnaroski that you and he are going to work on getting
a flightgear demo machine up for the linux expo thursday and Friday. John
indicated that he would very much like to get a CVS version with the new
traffic code up and running before the expo.
RE: --aircraft=ufo in system.fgfsrc is ignored
To change a 'feature', one that has been mentioned here many
times, and again recently, place the following code block
into fgInitFGAircraft.
In its favour, I would argue this means FG can be run without
a command line, provided FG_ROOT has been set in the
environment, and that seems to me, as it should be ... ;=))
Perhaps the only counter, is that system.fgfsrc is read twice,
but so are others, like .fgfsrc, for other (local) options ...
or system.fgfsrc should .nt. be used for 'aircraft' ?
The following patches to SimGear & FlightGear ...
- create an FGMetar abstraction layer, whose purpose is:
* provide defaults for unset values
* interpolate/randomize data (GREATER_THAN)
* derive additional values (time, age, snow cover)
* consider minimum identifier (CAVOK, mil. color codes)
- add rain/hail/snow/snowcover support on the METAR side
- add max age of METAR data handling (currently set to
- add support for an external METAR cache proxy server
- add CAVOK handling
- set missing year/month in regular METAR messages
- fix a small bug in metar.cxx (wrong return value)
explicit calls to shutdown_all() which was causing this to be called twice.
This could cause problems with some IO modules (such as attempting to close
an invalid file descriptor the second time.)
a single apt.dat.gz file which is in the native X-Plane format.
To do this I wrote a front end loader than builds the airport and runway
list. Some of the changes I needed to make had a cascading effect, so there
are minor naming changes scattered throughout the code.
I've finished the emigration of the radiostack, and I've also removed it
completely. It turned out that the comm radio is completely implemented in
the ATC subsystem. I've changed the affected ATC files to point
to /instrumentation/com, but I guess that the maintainer of the ATC code
should decide wether to make it configureable, and how.
I also had to change some files in Network and Main. The changes in network
should be obvious, but the changes in Main were a bit suspect. The files
included radiostack.hxx, but they weren't directly depending on
radiostack-hxx. They were depending on other files that were included by
radiostack.hxx. I got it to compile, but I'm not sure if I included the
correct directly depending file.
For the data directory I changed every occurrence of /radios/
with /instrumentation/ with this simple one-liner that I found on the net:
find -name '*.xml' -type f | xargs perl -pi -e
's/\/radios\//\/instrumentation\//g'
Instead of me sending all the files that got changed by this I suggest that
you execute the one-liner yourself. Of course I can not guarantee that this
will work perfectly, but I considered hand editing to be not an option (I'm
lazy). I don't want to test every aircraft to see if everything still works,
I think it's better to wait and see if anyone complaints about broken nav
radios/instruments.
Use a suggested exit method as described in the SDL_Quit man page. (fgOSExit() is still uncalled in both fg_os.cxx (glut) and fg_os_sdl.cxx, which makes these functions kind-of useless.) The other changes are fixes for gcc 3.3.4 warnings.
The caption should already be set when the window is opened. This is
important for some window managers. (KDE's kwin, for example, can store
special settings for certain windows, such as "no border" and "always
on top". KDE uses the window title to determine if a special rule is
to be applied. KDE will be made more tolerant, too.)
After applying the attached patches (based on latest CVS) you should
have a new option available within your version that should also
show up using fgfs --help, the syntax is:
fgfs --min-status={level} --show-aircraft
whereas "level" can be anything between
"alpha","beta","early-production" and "production"
Of course running something like
fgfs --min-status=alpha --show-aircraft
should not return any aircraft right now, as none of the
current aircraft definition files in your base-package is using the
required
<status></status>
tag - but you can easily give it a try by adding something like
<status>alpha</status>
The tag should be placed as a sub-tag within <sim> - so directly behind
the <description> tag would be just fine and straight-forward.
I've added two new debug log types for the instrumentation and systems. They
used to use the autopilot debug log, because I couldn't figure out how to
make new log types. Well, now I have figured it out. ;-)
Don't overwrite user settings from config files.
fgfs had in any case set bump-mapping to false, no matter if this
node did already exist (because it was defined in a config file).
This is a patch to make display list usage optional. They are on by default.
Use --prop:/sim/rendering/use-display-list=false to use immediate mode.
There is also a change in exception handling in main.cxx and bootstrap.cxx
erly known as trRenderFrame) is now declared as a NULL function pointer and ass
ignment of the proper function is now done in FlightGear (jpgRenderFrame=FGRend
erer::update).
a working state. I still see an anomoly when taking a screen shot from inside
a 3d cockpit, but external (chase/tower) views seem to work well. I also
added a property to control how many screen-res tiles are generated in the
output. Theoretically, you can now generate unlimited resolution screen shots,
or limited only by your disk space and patience.
Today I successfully generated a 20*1024 x 20*768 (20480x15360) resolution
screen shot. If you rendered that at 100 dpi it would cover a poster of
about 17 feet by 12.8 feet.
Good luck trying to display something that big or convert it to anything
useful on a typical PC. :-)
split). If SimGear is configured --with-jpeg-factory, then FlightGear
will fail to build unless this function is present.
FIXME: this is very messy architecturally -- find a better solution,
like passing this explicitly as a callback to the libJPEG class
(SimGear should not have a dependency on FlightGear).
Split up main.cxx into a program manegement part (which remains in
main.cxx) and a render part (the new renderer.?xx files). Also turn
the renderer into a small class of it's own. At this time not really
exctining because most of the stuff is still global, but it allows us
to slowly migrate some of the global definitions into the new class.
The FGRenderer class is now managed by globals, so to get the renderer
just call gloabals->get_renderer()
At some pijt it might be a good idea to also turn the remaining code in
main into a class of it's own. With a bit of luck we end up with a more
robust, and better maintainable code.
this was always only meant to be a test program for the metar lib, but now
that people are referring to it as a means to get metar reports, I think a
usage info is desirable. The list of test ids, on the other hand, isn't
necessary any more. This can still be handled by a Makefile or the commandline.
I'm all for keeping this tool in cvs, however. And also the not-used stuff
therein is a welcome source for how to use the SGMetar class.
A good elevation is critical for proper glide slope modeling. This patch
assigns the average field elevation to any ILS component that doesn't have
a valid elevation.
Also, for an ILS approach, use the GS transmitter elevation for glide slope
calculations rather than the localizer elevation, in some cases this can
make a big difference.
Wouldn't it be better to prepare the whole list of paths (or two
separate ones for Terrain/Objects if necessary) in FGGlobals::set_fg_scenery,
and to pass the vector<string>s to FGTileEntry::load? It doesn't seem to make
a lot of sense to split the path up, modify it, mount it together to one string
again, and then let FGTileEntry::load split it up again.
Here we go:
Main/globals.cxx
================
As fg_scenery is now a string_list, we don't need initialization. Furthermore,
this list is cleared with every set_fg_scenery() call.
ctor: create default dir from fg_root if necessary. Otherwise check all paths
of --fg-scenery/FG_SCENERY: If the path doesn't exist, ignore it. If it contains
a dir Terrain and/or Objects, then only add that to the list. If it contains
neither, then use the path as is.
Scenery/tileentry.cxx
=====================
Trivial: don't split a "base path", but use the given path_list as is.
(I considered a variable name "path_list" better suited than "search".)
Scenery/FGTileLoader.cxx
========================
No more fiddling with sub-paths. This has to be delivered by get_fg_scenery
already.
These change add some code that at initialization time will snap all
localizers into perfect alignment with their runways. It's my experience
that the DAFIF/FAA data reports runway and localizer headings to a level
of precision that is great for making charts, or adjusting your OBS, etc.
But the level of precision of this data can be far enough off to make you
visibly *un*aligned with the runway when the CDI needle is centered.
There are probably cases where the localizer isn't really perfectly
aligned with the runway, or intentionally misaligned to avoid obstacles
or terrain. So I have made this configurable for those that trust the
data more than I do. Just set "/sim/navdb/auto-align-localizers" to
true/false in the preferences file to turn this feature on or off in the
code.
- FG now directly supports Robin's native nav database file format.
- His latest data now separates out dme, gs, loc, and marker beacon
transmitters rather than lumping them all into a single "ILS" record.
- These new data structure changes prompted me to do some code restructuring
so that internally these different types of navaids are all kept as
separate lists and searched and handled separately.
- This structural change had a cascading affect on any code that
references or uses the nav databases. I've gone and "touched" a lot of
nav related code in a lot of places.
- As an added bonus, the new data (and code) adds DME bias so these will
all now read as they do in real life.
- Added Navaids/navdb.cxx and Navaids/navdb.hxx which provide a front
end loaders for the nav data.
- Added Navaids/navrecord.hxx which is a new "generic" nav data record.
- Removed Navaids/ils.hxx, Navaids/ilslist.cxx, Navaids/ilslist.hxx,
Navaids/mkrbeacons.cxx, and Navaids/mkrbeacons.hxx which are all now
depricated.
