This patch makes use of the vectors now available in simgear with that past
patch. And using that it simplyfies the carrier code somehow.
- Small additional factory's to the quaternion code are done in the simgear
part. Also more explicit unit names in the factory functions.
- The flightgear part makes use of them and simplyfies some computations
especially in the carrier code.
- The data part fixes the coordinate frames I used for the park positions in
the carrier to match the usual ones. I believed that I had done so, but it
was definitly different. Also there are more parking positions avaliable now.
The new multiplayer patch with an extension to transmit some properties with
the base package. The properties are transmitted in a way that will not
immediately brake the packet format if we need new ones.
Even if the maxmimum number needs to be limited somehow, that format might
work well until we have an improoved packet format which is even more compact
and that does not require to retransmit redundant information with each
packet.
That part is relatively fresh and based on that what Oliver provides on his
multiplayer server web page.
The properties are transferred to the client and I have modified the seahawks
rudder animation property to use a relative property path to verify that it
works appart from the fact that you can see it changing in the property
browser.
The movement is still a bit jerky, but that can be fixed/tuned later without
again braking the packet format.
This patch removes some useless indirection when creating AIModels. It
obsolets AIScenario*.
AIEntities are just an intermediate copy of an other intermediate copy of an
xml file on the way from the ai scenario configuration file to the AIModels.
As such the AImodels can now be created directly from the property tree read
from the scenario file.
This reduces the amount of work needed to add an other AIModel and reduces the
amount of copy operations done during initialization.
It also moves internal knowledge of special AI models into these special AI
models class instead of spreading that into the whole AIModel subdirectory
which in turn enables to use carrier internal data structures for carrier
internal data ...
Also some unused variables are removed from the AIModel classes.
I believe that there are still more of them, but that is what I stumbled
accross ...
Tested, like the other splitouts these days in a seperate tree and using the
autopilot for some time, and in this case with a carrier start ...
This patch is a combined effort by Gregor Richards, Oliver Schroeder, and
Vivian Meazza (and code cleanups and improvements by Erik Hofman). It corrects
the bug in which a Multiplayer model responds to local inputs, and the view
number bug which caused certain aircraft to appear as cockpit only models. It
passes remote properties over the net, and all major control surfaces and gear
are now animated correctly, providing that the local ~model.xml file contains
no leading "/" in the <property></property> data entries. MP objects
are now extrapolated using 1st and 2nd derivatives to make their movement
appear more smooth. The sim is now halted while a new client joins the net.
Known problems with MP are non-display of the remote client under certain
circumstances of starting/resetting, and a freeze on starting. These bugs are
long standing, and are not addressed by this patch.
Special thanks must go to AJ Macleod for his patient testing of this patch over many evenings.
We have also moved part of multiplayer into AIModels as part of the ongoing
development of MP.
- Feet to meter conversion mistake (in AI getGround elev)
- Improved ground following code (not yet perfect, but for now no one will
notice it within the marginal altitiude differences at the taxitrack or
runway)
- Exclusion of the "AI" directory witihin data/Aircraft in
main/init/fgSearchAircraft, to prevent AI aircraft to be picked up by the
aircraft search function
- fix indentation (there were 2, 3, 4, 7(!) space indents as well as tab
indents, all mixed together)
- no code changes, except one "if (foo) {}" changed to "if (!foo) return; ..."
Here's a fix for a bug I introduced when I updated the AIStorm with
turbulence. The change I made to the FGAIEntity struct was overriding the
thermal <strength-fps> data.
"the model is deref'd and deleted when the refcount is null *but* it is
still referenced in the ai model list, so next time you ask for it you will
have a reference on something deleted"
I tried to make sure accessor functions which return by reference act
on const objects. also replaced some iterators with const_iterator
and a few return/pass by reference that were missed the first time
around.
* Use "const string&" rather than "string" in function calls when appropriate.
* Use "const Point3D&" instead of "Pint3D" in function calls when appropriate.
* Improved course calculation in calc_gc_course_dist()
* Safer thread handling code.
Vassilii Khachaturov:
Dont use "const Point3D&" for return types unless you're absolutely sure.
Erik Hofman:
* Use SGD_(2)PI(_[24]) as defined in simgear/constants.h rather than
calculating it by hand every time.
Auf Niederlandisch:
Bij deze de patch voor de taxiway code. Deze code is nog gebaseerd
op de bestaaande architectuur, gebaseerd op de FGAirport class in simple.[ch]xx
Ik heb me voornamelijk gericht op nieuwe functionaliteit; de volgende
submissie zal waarschijnlijk bestaan uit opschoning, opsplitsing en een
implementatie van de nieuwe airport architectuur, zoals voorgesteld door
David Luff.
En Anglais:
Here is the patch for the taxiway code. This code is still based on the
exsisting architecture, which is based on the FGAirport class in simple.[ch]xx
I've aimed mostly at new functionality; The next batch will probably contain
code cleanups, splitups and the implementation fo the new airport architecture,
as proposed by David Luff.
I had a quick view over the ssgBase::ref() calls in flightgear.
I made them all symmetric and used ssgDeRefDelete to dereference them.
This has the basic advantage that ssgDeRefDelete additionaly deletes the
memory instead of just decrementing the reference cound without deletion ...
This includes an incorrect deref instead of a ssgDeRefDelete in the placement
transform registration I introduced earlier. I believe that this causes the
problems with long flights (unverified, but with a big propability).
This adds a TACAN instrument to the inventory. Range and bearing are calculated
to the TACAN or VORTAC beacon selected by means of the Channel Selector in the E
quipment/Radio pull-down menu.
A TACAN beacon has also been added to the aircraft carrier Nimitz (channel #029Y
).
There was a patch from Manuel Masing a few months ago which cleaned up
SGLocation's way depending on input values. That means that with that patch
SGLocation does no longer have calls with unneeded input arguments.
I took his patch and integrated that into flightgear and made maximum use of
that changes.
Erik Hofman:
Remove some duplicate code that was moved to simgear/compiler.h
Some quite extensive changes to the AIModel code:
1. Mathias has made major changes to the AICarrier code to provide better
alignment of an aircraft on deck with the carrier - this feature is a major
improvement on the existing, but has a bug which might cause it to fail when
the computer carries out other tasks - changing window size is a known
example. This bug is outwith this code.
2. I have made significant changes to the AIShip code to enable a ship the
turn and roll smoothly.
3. I have added some simple AI which enables the carrier to remain within,
or return to, an operating box.
4. An automated turn into wind for flying operations.
5. A simplistic implementation of TACAN within AICarrier. I am in the course
of implementing this as a generic instrument, but this is some time off
completion.
I have prepared a patch that:
- Introduces a FGTileMgr::scenery_available method which asks the tilemanager
if scenery for a given range around a lat/lon pair is already loaded and make
use of that method at some -9999 meter checks.
- Introduces a FGScenery::get_elevation_m method which queries the altitude at
a given position. In constrast to the groundcache functions this is the best
choice if you ask for one *single* altitude value. Make use of that thing in
AI/ATC classes and for the current views ground level. At the current views
part the groundcache is reused if possible.
- The computation of the 'current groundlevel' is no longer done on the
tilemanagers update since the required functions are now better seperated.
Alltogether it eliminates somehow redundant terrain level computations which
are now superseeded by that more finegrained functions and the existence of
the groundcache. Additionally it introduces an api to commonly required
functions which was very complex to do prevously.
- AIManager.cxx :
- we can now have multiple <scenario> entries in the sim/ai entry in preferences.xml
- AIBase.cxx :
- added an exception handler around the loading of the 3D model to not exit FG
if the model is not found
- AIScenario.cxx :
- removed a duplicated read of the xml file, this was also exiting FG is the xml file
does not exist
I have traced that reset on carrier problem down to several problems. One of
them is the fact that on reset the carrier is updated while the aircraft is
not. That made the aircraft drop down an elevator sometimes. Depending on the
passed realtime while loading some parts of the scenery.
I have introduced the posibility to start directly on the carrier.
With that patch you will have a --carrrier=id argument where id can either be
the pennant number configured in the nimitz scenario or the carriers name
also configured in the carriers scenario.
Additionaly you can use --parkpos=id to select different positions on the
carrier. They are also configured in the scenario file.
That includes the switch of the whole FGInterface class to make use of the
groundcache.
That means that an aircraft no longer uses the current elevation value from
the scenery class. It rather has its own local cache of the aircrafts
environment which is setup in the common_init method of FGInterface and
updated either manually by calling
FGInterface::get_groundlevel_m(lat, lon, alt_m);
or implicitly by calling the above method in the
FGInterface::_updateGeo*Position(lat, lon, alt);
methods.
A call get_groundlevel_m rebuilds the groundcache if the request is outside
the range of the cache.
Note that for the real usage of the groundcache including the correct
information about the movement of objects and the velocity information, you
still need to set up the groundcache in the usual way like YASim and JSBSim
currently does.
If you use the native interface, you will get only static objects correctly.
But for FDM's only using one single ground level for a whole step this is IMO
sufficient.
The AIManager gets a way to return the location of a object which is placed
wrt an AI Object. At the moment it only honours AICarriers for that.
That method is a static one, which loads the scenario file for that reason and
throws it away afterwards. This looked like the aprioriate way, because the
AIManager is initialized much later in flightgears bootstrap, and I did not
find an easy way to reorder that for my needs. Since this additional load is
very small and does only happen if such a relative location is required, I
think that this is ok.
Note that moving on the carrier will only work correctly for JSBSim and YASim,
but you should now be able to start and move on every not itself moving
object with any FDM.
I added an AIStatic object to my OV-10 sim for use in putting city signs,
vehicles, or anything else that will be static, but that I don't want to put
in the scenery files. It's inexpensive. Before, I was making such things
from AIShip.
I also added the ability to set flight plans to repeat, so that when an
airplane reaches the end it just starts over at the beginning. This is
useful for my OV-10 sim. I have C-141 and KC-135 traffic flying approaches
to Ramstein, and I only have to define two AI objects to do this.
Also, I found an inefficiency in AIBase, where every AI object was calculating
Mach number at every dt. Now only AIBallistic objects do this.
1) The AIStorm sets the properties:
/environment/turbulence/magnitude-norm
/environment/turbulence/rate-hz
The actual turbulence effects are handled by the FDM.
If the effects are deemed unrealistic, then that will
have to be fixed in the FDM(s).
2) The zone of turbulence is cylindrical, and is centered
at the AIStorm's lat/lon. The diameter is set with
<diameter-ft>, the top with <height-msl>, the bottom is
assumed to be at <altitude> minus 1000 feet.
3) Note that the zone of turbulence may not match well with
the visual model of the storm. In this case I had to
x-offset the storm model by 4700 meters to match the zone
of turbulence. (i.e. the storm model is 4700m off center).
4) While I was in there I also increased the speed of the
lightning flashes to look more realistic.
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.
I'm looking through the AI code, trying to find the bug that's killing the
thermals. The following things don't look right:
1) AIManager::101 , the Traffic Manager pointer is searched for by name at
every dt. I'll leave this for you to look at.
2) AIManager::295 , the thermal height is not being set. We need to
restore the line: ai_thermal->setHeight(entity->height_msl);
This fixes the thermal problem.
3) AIManager::328 , I changed the fetching of the user state to occur every
sim cycle, and changed the fetching function from by-name lookup to a lookup
by node pointer. It should be faster now, and more accurate too. This helps
the air-refueling.
- don't treat *every* child in the xml as submodel, especially not a "param"
block
- do not only *enable* the contrail flag above some altitude, but also
disable it below
I have done some cleanup where I moved some values out of classes where they
do not belong and such stuff.
Also the fols offsets are now named in the carrier xml file with a more
verbose name (flols-pos/offset-*) than before (only offset-*).
There is a little preparation for definitions of parking positions on the
carrier which should later be used for starting flightgear directly on the
carrier.
I attach the long-promised improved version of the USS Nimitz.
It includes an improved version of the FLOLS, which requires the attached
diff to be applied to AICarrier.cxx and AICArrier.hxx.
I've made lots of eye-candy in the form or the flightdeck crew.
Unfortunately, it about doubles the size of the tarball. I'll send it to you
later; when I've figured out some way of only loading on request (any advice
would be very welcome).
I could provide a \u2018bare\u2019 version to cut down on the vertex count for
less capable systems however, the count isn\u2019t huge in the first place.
I've cut the textures down as far as I can without losing definition.
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.
We should now be able to find
wires or catapults when the ac3d model is loaded without the crease patch
(caused by the much more unstructured scene graph emitted by the old loader).
It should also emit more warnings if the carrier hardware configuration
includes conflicting definitions.
That code is the most intrusive one, it should not be used until you configure
an aircraft carrier as a aimodel. So I think it should be save to apply that
before the release too.
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 have a small update which fixes the algorythm used for marking solid
surfaces for some cases where some branch nodes carry the object names I had
expected in the leaf nodes.
That will also introduce the possibility to mark whole subtrees from the
scenegraph solid.
This is a sub-system which can be added to any carrier.
These files add a functioning Fresnel Lens Optical Landing System (FLOLS).
The orange/red 'source' lights are illuminated according to the position of
the pilot's eye above/below the 3.5 deg glide slope. The apparent position
of the source light relative to the fixed green datum lights allow the pilot
to 'fly the meatball'. The green 'cut' lights flash when the pilot's eye is
below the coverage of the lowest (red) source light.
TODO - add rules for the operation of the wave-off lights.
Okay, here's the latest update to the tarffic manager/AI Manager. AITraffic
can now fly multiple routes and be initialized while sitting statically at
airports.
The moving ai models will jump around realtive to the moving aircraft model.
I can see that with the carrier but others have noticed that too with ai
aircraft before.
The reason is that all SGSystems are called with a dt value which is not
necessarily a multiple of 1/hz.
In contrast, most FDM's use the _calc_multiloop function from FGInterface
which forces the time update to be a multiple of 1/hz for the FDM aircraft.
As a result, in the worst case, the FDM aircraft has moved nearly 1/hz seconds
further than the rest of flightgear (1/120sec*300kts that is about 1.3m).
That patch forces the time update to be a multiple of 1/hz.
I attach the latest version of Nimitz. The textures have been improved. A glide-path has been added, it is on by default, but can be switched off by means of the properties browser: /ai/models/ship/controls/glide-path. The origin has been adjusted to the turning pivot and approximate roll center.
Modified AiShip files are also attached. These allow the radius of the turning circle of a ship to be input. The turning circle is adjusted for speed and rudder angle. Roll has been corrected so that a ship leans out of a turn, not inwards like an aircraft. The roll angle is adjusted for speed and rudder angle (yes, application of more rudder reduces roll angle - rudders act as stabilizers).
TODO
Add a relative wind calculation so that a carrier can be turned to the appropriate launch and recovery courses.
Add a 'flight plan' so that the carrier can carry out a racetrack for flight ops.
Add a projector landing sight.
Add auto-land facilities.
Here are files to get automated contrails working. I've set up contrails for
the 737, using my simple, untextured contrail model. Vivian has made another
contrail model, but I'm still trying to get his to work. I'm hoping others
will try to make contrail models also.
Here's some code that defines a top to thermals. When the top of a thermal is
reached the strength is phased-out linearly over the next 100 feet of
altitude. At first I tried just capping the thermal at the top, but the
change in thermal strength was too fast for the FDM to handle well.
Included is a new version of the thermal scenario that includes a top
(height-msl) to the thermal. The default value is 5000 feet.
As a result of recent requests, I've implemented the ability to switch off
aerodynamic stabilisation:
This has to be added to the submodel.xml files:
<aero-stabilised>false</aero-stabilised>
When false the submodel retains the pitch given at instantiation.
It defaults to true.
I think I found the problem in props.hxx. I have an exception when copying properties. An alias to a property that has no value trigger this exception. The code that generate that is in AIManager.cxx :
void FGAIAircraft::bind() {
FGAIBase::bind();
props->tie("controls/gear/gear-down",
SGRawValueMethods<FGAIAircraft,bool>(*this,
&FGAIAircraft::_getGearDown));
props->getNode("controls/lighting/landing-lights", true)
->alias("controls/gear/gear-down");
}
controls/gear/gear-down has no value ( _type == NONE ) and controls/lighting/landing-lights is copied somewhere.
Erik:
Frederic's fix was to change props.hxx but he has expressed his doubts.
For now I've commented out the line that causes the problem so we have more
time to look deeper into the problem.
cvs -z4 -q diff -u props.hxx (in directory I:\FlightGear\cvs\SimGear\simgear\props\)
Index: props.hxx
===================================================================
RCS file: /var/cvs/SimGear-0.3/SimGear/simgear/props/props.hxx,v
retrieving revision 1.4
diff -u -r1.4 props.hxx
--- props.hxx 19 Sep 2004 09:08:12 -0000 1.4
+++ props.hxx 21 Oct 2004 07:10:54 -0000
@@ -622,7 +622,7 @@
/**
* Test whether this node contains a primitive leaf value.
*/
- bool hasValue () const { return (_type != NONE); }
+ bool hasValue () const { return (_type != ALIAS && _type != NONE) || (_type == ALIAS && _value.alias->_type != NONE); }
/**
I've finished the variation of Cd with Mach number.
The calculations are only applicable to ballistic
objects, and then strictly one shape: non boat-tailed bullets/shells, so
I've put them in AIBallistic rather than AIBAase. For all inputs, Cd
should be the sub-sonic value, so bullets will need changing.
I've just posted a graphical analysis here:
http://myweb.tiscali.co.uk/vmeazza/FlightGear/cd_mach.pdf
The calculation of submodel mass from weight has been moved from AIBallistic
to Submodel so that it is calculated only once, rather than on every
iteration as a present. The parameter <contents> has been added, primarily
so that droptanks will have the proper mass. It is the path to an
appropriate property containing a weight in lbs.
Care has to be taken with the use of <contents> because after a reset there
appears to be a delay in submodel instantiation (dt not properly reset???)
and the weight property is not always picked up before it is set to zero in
the key bindings. Slightly hard to explain. It works fine if FGFS has not
been reset though. There is a partial solution which involves the rejigging
of the fuel and gui nasal scripts, but there is still the visible delay in
instantiation to be resolved. I've nearly done the nasal fixes, which will
form part of an update to the Hunter only. I'll probably complete those
later today.
The value of rho (air density) varies with height. (Including the upper
stratosphere, ust in case someone wants to model ICBMs.) The standard
atmosphere is used (based on a sea-level temperature of 15 deg C.).
Erik Hofman:
I moved this code over the AIBase::update() so all AIModels can make
use of rho, temperature, pressure, etc.
I have added <Cd> and <weight> to the input parameters in the submodels.xml
script. Raw data may be used, thus avoiding the need to guestimate <eda>.
Eda remains, but should now be used to enter the proper cross-sectional
area.
I had to reverse a number of signs to get it right. I took the opportunity
to add roll to the submodel so that droptanks will come off with the right
orientation. I have neither added the rotational speed to the submodel, nor
yaw, so if you release droptanks with significant roll rate or yaw angle on
the aircraft the submodel will not be quite right. Straight and level, or
nearly so, is fine.
The maths, so far, is now correct. Roll and pitch are now both in the
correct sense. The aircraft velocity is added correctly to the
submodel velocity, and the submodel is now visible when instantiated.
However, the velocity is measured at the aircraft centre. To be totally
correct we ought to take into account the aircraft's rotational
velocity. We have pitch rate and roll rate available, but not yaw rate
(small anyway).
I've added another parameter to the submodel - wind.
It's activated by the entry <wind>true</wind> in the ../submodel.xml file.
If true, the submodel is affected by the local wind, otherwise not. The
parameter defaults to false. This is useful for exhausts and smoke, and
possibly all objects.
Attached are the modified files to add buoyancy as a parameter for a
ballistic object. It may be set by adding
<buoyancy>x</buoyancy> to the submodel .xml file, where x is the appropriate
value (ft per sec2):
32 neutral buoyancy - contrails
>32 positive buoyancy - exhaust plumes
(0 non-op - default value)
If <buoyancy>x</buoyancy> is not used, then there is no effect on the
current ballistic model
Silly me. I was starting the timer at zero, so the first tracer didn't fly
until 0.25 seconds after pulling the trigger. Now the timer starts at the
same value as "delay", so the first round comes out immediately.
Also, I've added an optional configuration attribute that allows you to change
the ballistics of the submodel. This allows parachutes, or anything else
that has ballistics different from a bullet. The attribute is called "eda",
which is the equivalent drag area. Default value is 0.007, which gives the
same ballistics as the current tracers. Increasing this value gives more
drag. A value of 2.0 looks good for a parachute.
math stuff
########################################################################
The deceleration of the ballictic object is now given by:
[ (rho) (Cd) ] / [ (1/2) (m) ] * A * (V * V)
where rho is sea-level air density, and Cd and m are fixed, bullet-like
values. So the calculation is:
0.0116918 * A * (V * V)
The value "A" is what I'm calling the "eda" (equivalent drag area).
########################################################################
A parachute model will have to be built so that the parachutist's feet
are in the forward x-direction.
Here is the submodel.xml config I use for "parachutes":
<submodel>
<name>flares</name>
<model>Models/Geometry/flare.ac</model>
<trigger>systems/submodels/submodel[0]/trigger</trigger>
<speed>0.0</speed>
<repeat>true</repeat>
<delay>0.85</delay>
<count>4</count>
<x-offset>0.0</x-offset>
<y-offset>0.0</y-offset>
<z-offset>-4.0</z-offset>
<yaw-offset>0.0</yaw-offset>
<pitch-offset>0.0</pitch-offset>
<eda>2.0</eda>
</submodel>
I've included the latest fixes to the Traffic Manager/AI flightplan generation
code. Most of the code changes are in AIFllightplan.cxx. This is the code
that runs without depending on predefined FlightPlans in
#FG_ROOT/Data/AI/Flightplans.i
As suggested by Dave, I've also added a new property in
preferences.xml: /sim/traffic-manager/enabled, which is used to control
whether or not the traffic manager is active.
I'm still working on a few more 737 traffic patterns, those are going to take
a little longer, so I didn't want to wait sending in this code.
Finally, I haven't put much effort into ensuring "aeronautical correctness" in
this version yet. The code works on my system, but what the AI plane do may
actaully be quite rediculous. But I'd like to leave that for the next
version.
Here's some additions to AI that allow refueling from an AI tanker (the actual
onload of fuel must be handled by the user's FDM of course, this just lets
the FDM know that the user is in position to refuel).
I've added a new class of AIAircraft called "tanker". It uses the same
performance struct as a jet transport. An AI tanker is just like an AI jet
transport, except it uses the already-existing radar data to control the
boolean property systems/refuel/contact. The code change was minimal.
An AI tanker can be created like this:
<entry>
<callsign>Esso 1</callsign>
<type>aircraft</type>
<class>tanker</class>
<model>Aircraft/737/Models/boeing733.xml</model>
<latitude>37.61633</latitude>
<longitude>-122.38334</longitude>
<altitude>3000</altitude>
<heading>020</heading>
<speed>280</speed>
<roll>-15</roll>
</entry>
This puts a tanker over KSFO at 3000 feet, in a left-hand orbit. When the
user gets within refueling range (contact position) then the property
systems/refuel/contact will be true. Otherwise it is false.
The dimensions of the refueling envelope are pretty rough right now, but still
usable. The user must be behind the tanker (ie. radar y_offset > 0). The
user must be at or below the tanker's altitude (ie. radar elevation > 0).
The user's lat/lon must be within 250 feet of the tanker's lat/lon (ie. radar
range_ft < 250). This last requirement is loose because the radar data is
only updated every 100 ms, which is accurate enough for radar use, but
which is sloppy for air refueling. This could be tightened up by increasing
the radar update rate to once every sim cycle.
I'm going to add a light to the T-38 instrument panel that will monitor the
property systems/refuel/contact. This will make it easier to explore the
boundaries of the refueling envelope.
Here's some new AI stuff.
1) AI objects must now be defined in a scenario file, not in preferences.xml
or a *-set file. (Of course this doesn't prevent objects from being created
dynamically, as with Durk's traffic manager).
2) A new demo_scenario file is attached. It creates 3 aircraft, a sailboat,
and a thunderstorm.
3) Objects without flightplans live forever.
4) FGAIShip::ProcessFlightplan() is not yet implemented.
5) preferences.xml should now define only <enabled> and <scenario>
1. Removed aircraft roll on ground.
2. Decreased descent pitch angle.
3. Updated flightplans to include <on-ground>
4. Fixed property indexing, so all AI aircraft have their own property branch
The default value of <on-ground> is false, so you only need to specify it when
on the ground. For takeoff you need to specify <on-ground>true</on-ground>
for the first waypoint, and for the acceleration waypoint. For landing you
need to specify it for the touchdown point and any taxi points.
One problem. WARNING **** There is a bug in the way the property system
works, which causes a segfault, but I don't know if the problem is in the
property code, or in how I'm using it. After an AI object terminates, if you
access the property tree through the property browser the sim will segfault.
First, preferences.xml will define the scenario filename.
For now, the other way of defining ai objects still works, so the sailboat
stays in preferences.xml. Later, I'll move the sailboat into the demo
scenario. If no scenario filename is given, then no scenario will be
processed.
I changed the demo scenario to create two 737's, one takes off on runway 01L,
and the other takes off on runway 01R. This will make a good demo for the ai
system. One problem, if you takeoff on 28L/R right away, you might run into
the taking-off 737's, or be scared.
Here's the newest AI stuff.
The AIManager at init() creates a new scenario. Right now the
default_scenario is hard coded in, but eventually the AIManager should get
the scenario filename from preferences.xml.
The scenario defines which AI objects will be created. Right now it only
creates AIAircraft, but this is easily extended. The scenario also defines
which flightplan will be assigned to the airplane. Scenario config files go
in data/Data/AI.
The Airplane gets a pointer to a FlightPlan object. Each airplane should get
its own flightplan object, even if two airplanes have the same flight plan.
This is because the flightplan maintains the iterator pointing to the
current waypoint, and two airplanes might be at different locations (for
instance if they were created at different times). The flight plan files go
in data/Data/AI/FlightPlans.
When the airplane gets to the waypoint named "END" it vanishes. The
AIAircraft destructor deletes its flight plan (if it has one).
The last waypoint is a place holder only. I called mine
<WPT><NAME>"EOF"</NAME></WPT>.
I added some things to the AI stuff to improve the AIThermal processing.
Before, all the thermals were processed in order, and the last one overwrote
the prior one. Now, only the data from the nearest thermal is kept. This
way a tile can be populated with many thermals, and (as long as they have the
same diameter) the one nearest the airplane correctly takes effect. This
will make us ready for the next step, "auto-thermaling", where FlightGear's
tile manager can cover a tile with thermals, and set the thermal strength
based on land-use type.
I moved the enumerated object_type to the base class. When an AI object is
created it now sets the _otype variable in the base class. This lets the AI
manager find out what kind of AI object it is dealing with, using the base
pointer. I also added a function isa() to the base class, so the manager can
process objects differently based on their type.
The AI manager now sends AIThermal processing to a different function, where
only the data from the nearest thermal is kept. After the manager processes
all the AI objects, then the results from the nearest thermal are applied to
wind-from-down.
Here's a new batch of AI code which includes a working radar instrument.
I put the radar calculations into the existing AIAircraft class. It was
easier that way, and it can always be migrated out later if we have to.
Every tenth sim cycle the AIManager makes a copy of the current user state
information. When the AIAircraft updates it uses this information to
calculate the radar numbers. It calculates:
1) bearing from user to target
2) range to target in nautical miles
3) "horizontal offset" to target. This is the angle from the nose to the
target, in degrees, from -180 to 180. This will be useful later for a HUD.
4) elevation, in degrees (vertical angle from user's position to target
position)
5) vertical offset, in degrees (this is elevation corrected for user's pitch)
6) rdot (range rate in knots, note: not working yet, so I commented it out)
and three items used by the radar instrument to place the "blip"
7) y_shift, in nautical miles
8) x_shift, in nautical miles
9) rotation, in degrees
The radar instrument uses the above three items, and applies a scale factor to
the x-shift and y-shift in order to match the instrument's scale. Changing
the display scale can be done entirely in the XML code for the instrument.
Right now it's set up only to display a 40 mile scale.
The radar is an AWACS view, which is not very realistic, but it is useful and
demonstrates the technology. With just a little more work I can get a HUD
marker. All I need to do there is make a bank angle adjustment to the
current values.
I went through the AI code to put the "bank" node back into the config file,
so the models can fly circles. While I was in there I made some other
changes.
*) Moved the initialization of roll, tgt-roll, pitch ... etc, from init()
into the constructor, so it wouldn't over-write the config settings.
*) Changed the altitude getter to remove the meters-to-feet conversion. The
altitude is kept internally in feet. Only the scenery code needs meters.
*) Added "bank" item for config file (for type=aircraft). Left bank is
negative.
*) Added "rudder" item for config file (for type=ship). Left rudder is
negative. Internally this is stored in the "roll" variable, but the ship
model doesn't roll. It uses the "roll" variable for turning though.
The following puts a tanker at 3000 feet, 6 nm northwest of KSFO. On takeoff,
the tanker is visible over the hanger building at one-o'clock.
<entry>
<type>aircraft</type>
<class>jet_transport</class>
<path>Aircraft/737/Models/boeing733.xml</path>
<speed-KTAS type="double">320.0</speed-KTAS>
<altitude-ft type="double">3000.0</altitude-ft>
<longitude type="double">-122.455</longitude>
<latitude type="double">37.69667</latitude>
<heading type="double">200.0</heading>
<bank type="double">-15.0</bank>
</entry>
