the tile cache it's ssg elements are disconnected from the main ssg scene
graph, and then the tile is thrown on the end of a delete queue. The
tilemgr->update() routine runs every frame. It looks at this queue and if
it is non-empty, it incrementally frees the compents of the first tile
on the queue. When the tile is completely free it is removed from the queue.
The amount of time to free the memory for even a single tile can be quite
substantial, especially with the increased overhead of dynamic/random
ground objects. This change allows the system to spread the work of freeing
tile memory out over many frames so you don't get a noticable single frame
hit or stutter.
the triangles containing the objects were out of the view Frustum,
they were never traversed by ssg (and thus, never culled). Now, every
200 frames, do a pass through the whole scene graph with cull-testing
disabled and without drawing anything; that will allow random-objects
to be collected incrementally.
-----------------------------------------------
Fixed a segfault on exit.
Changed the radius of the dummy bounding sphere from 10m to 1000m to
ensure that FOV culling doesn't leave anything out.
Allow an object to have more than one variant model, which will be
chosen randomly. Simply repeat the <path>...</path> property.
Removed the <billboard> property and replaced it with <heading-type>,
which can be set to "fixed" (leave the model oriented as it is),
"random" (give the model a random heading between 0 and 359 deg), or
"billboard" (always turn the model to face the camera). The default
is "fixed". Models look much better when they are not all facing the
same direction.
Allow the user to group models with the same visual range, so that
there can be *many* fewer nodes in the scene graph when the models are
not visible. This causes an XML-format change, so that instead of
<object>
<range-m>...</range-m>
...
</object>
<object>
<range-m>...</range-m>
...
</object>
...
we now have
<object-group>
<range-m>...</range-m>
<object>
...
</object>
<object>
...
</object>
...
</object-group>
Every object in a group can still have its own model(s), coverage, and
heading-type, but they all share the same range selector.
This change should already help users with tight memory constraints,
but it will matter much more when we add more object types -- for
example, we can now add dozens of different urban building types
without bloating the scene graph or slowing down the LOD tests for
tris that are out of range (i.e. most of them).
1. Only one copy of each object (and its texture) is stored in memory,
no matter how many materials use it.
2. Random objects are added to a triangle only when the objects are in
range, and they are deleted as soon as the objects are out of
range. That way, only a relatively small number of ssg nodes are
used at any one time.
This patch seems to eliminate freezes when tiles are freed. There are
occasional stutters at extremely high speeds (i.e. over 3,000kt), but
it seems smooth enough for normal aviation speeds.
- no extra nodes are created at all if the material has no random
objects defined
- the range selector is place correctly under the transformation
- there is only one range selector for each object type in each
triangle (experimental -- doesn't seem to make a difference in speed
or memory)
This patch removes Curt's patch that randomized ranges slightly, since
individual random objects no longer have their own range selectors.
It also leaves the object-group-range value unused, for now.
- tidies up the update-time-step handling (making it a simple "dt");
- makes the altimeter get a proper pressure, and the (unused) vacuum
calculation get a proper RPM (*);
- replaces property name look-ups with static pointers to property nodes.
Notes from DPM:
- the static pointers are a very bad idea, but they're only temporary;
I plan to make FGSteam into a proper subsystem soon, and then they
can be member variables
- I fixed the patch to get the current static pressure from the
/environment/pressure-inhg property, so that the altimeter interacts
properly with FGEnvironment
The present sets of bindings result in the throttle being "squared"
about its centre, which is silly. This is because the "squared"
parameter is not set by the throttle binding, but the default is
"true". We discussed this before and I think there was general
agreement that the default should be "false" on the basis of
generality.
situations for every kind of airplane. But at the moment we have nothing
implimented and this will cover the simpler cases until someone has a
chance to impliment a fuller solution.
GL/gl.h can't be included at the first position in windows. It requires
the inclusion of windows.h that must be included in other fgfs header
file. I only move down #include <GL/gl.h>
This patch eliminates about 10 of valgrind's "Use of uninitialised
value of size ..." messages. They are all caused by approachlist building
incomplete FGApproach class instances and then copying them into the
approchlist container, hence copying data garbage.
I know, I couldn't win a beauty contest with this patch, but the
alternative approach -- letting operator<< always leave complete
entries -- didn't look any better. And I do only add those seemingly
useless initialization where the values would be used uninitialized
else. The constructors are only run during setup and won't slow fgfs
down at runtime.
Make locally-used strings local instead of global. (The safety and
cleanliness benefit outweights the slight performance hit. If
performance is an issue, the way these strings are used should be
optimised.) Use existing defined constant instead of a literal
number.
+ The panel(s) are now an first-class SSG node inside the aircraft
scene graph. There's a little code added to model.cxx to handle the
parsing, but most of the changes are inside the new FGPanelNode
class (Model/panelnode.[ch]xx).
+ The old FGPanel source changed a lot, but mostly cosmetically. The
virtual-cockpit code moved out into FGPanelNode, and the core
rendering has been abstracted into a draw() method that doesn't try
to set any OpenGL state. I also replaced the old inter-layer offset
code with glPolygonOffset, as calculating the right Z values is hard
across the funky modelview matrix I need to use. The older virtual
panel code got away with it by disabling depth test, thus the "panel
draws on top of yoke" bug. PolygonOffset is really the appropriate
solution for this sort of task anyway.
+ The /sim/virtual-cockpit property is no more. The 2D panels are
still specified in the -set.xml file, but 3D panels are part of the
model file.
+ You can have as many 3D panels as you like.
Problems:
+ The mouse support isn't ready yet, so the 3D panels still aren't
interactive. Soon to come.
+ Being part of the same scene graph as the model, the 3D panels now
"jitter" in exactly the same way. While this makes the jitter of
the attitude gyro less noticeable, it's still *very* noticeable and
annoying. I looked hard for this, and am at this point convinced
that the problem is with the two orientation computations. We have
one in FGLocation that is used by the model code, and one in
FGViewer that is used at the top of the scene graph. My suspicion
is that they don't agree exactly, so the final orientation matrix is
the right answer plus the difference. I did rule out the FDMs
though. None of them show more than about 0.0001 degree of
orientation change between frames for a stopped aircraft. That's
within an order of magnitude of what you'd expect for the
orientation change due to the rotation of the earth (which we don't
model -- I cite it only as evidence of how small this is); far, far
less than one pixel on the screen.
[and later]
OK, this is fixed by the attached panel.cxx file. What's happened is
that the winding order for the text layer's polygons is wrong, so I
reverse it before drawing. That's largely a hatchet job to make
things work for now, though. We should figure out why the winding
order is wrong for only text layers and fix it. I checked the plib
sources -- they're definitely doing things CCW, as is all the rest of
the panel code.
Odd. I'm also not sure why the 2D panel doesn't care (it works in
both winding orders). But this will allow you to check in working
code, anyway. There's a big comment to this effect in there.
instrument. This needs to move somewhere permanent.
Also, remove a bogus fuel consumption setting that (1) was off by a factor
of 3600 (hours, not seconds) and (2) collided with identical code in FGFDM.
the amount of drag that the produced lift *would* have produced given an
unflapped air surface. A nifty trick involving the assumption that AoA is
small works for this, and produces plausible results in the high AoA case
as well.
Also, trim for approach using the elevator-trim control, not elevator.
Just cosmetic for current planes, but future ones might have differing
implementations of trim.
This is the small code fix which is needed for the new options.xml file.
It is needed because otherwise the "--prop:name=value" is showed
incorrectly.
There is another problem though, when compiling with --without-logging
the help message isn't displayed at all! We *must* change that somehow.
Curt: good point, the SG_LOG()'s have been switched to cout's ...
(and not the throttle setting), but the recalculation left in a degeneracy
when the target/throttle setting was exactly zero. Zero times a big number
is still zero. Fixed to use real math, not theoretical math.
- More progress with proper radio freq tuning and proper interpreting of the
hardware values.
- Filter ignition and flap switch values since the hardware implimentation has
a dead zone where the value can go to zero in the middle of a change in
switch position.
I've updated the FIXME in the code, and fixed a typo (descr instead of
description), but the SG_LOG() functions doesn't produce any output for
me. Could you confirm it's still working for you?
Curt Olson:
I did a bit of further tweaking and it all looks good now. The tricky thing
is that SG_LOG() always appends an endl at the end of every message.
This is an enhanced version of the options patch.
It's more robust now, and gives some helpful information if something
goes wrong. Also the naming in the options.xml file has changed to the
syntax David suggested.
Since no one objected to the patch I think it is safe to included it.
class, FGModelPlacement, while FG3DModel retains control of animation.
This way, we can have a single, top-level placement, but multiple
layers of nested models underneath. To include a nested model, use
something like this in the XML wrapper:
<model>
<path>Models/Stuff/my-component.xml</path>
<offsets>
<roll-offset-deg>45</roll-offset-deg>
</offsets>
</model>
contain colon-separated ranges. For examples, winds from 180 degrees
10 knots gusting 15 knots would be
--wind=180@10:15
Winds variable from 180-220 degrees 5 knots would be
--wind=180:220@5
FGEnvironment does not yet support variable-direction winds, so
nothing will yet happen in the second case.
Modifications to support querying navaid database by station ID (not just
frequency.) Some corresponding changes to testnavs.cxx to test new
functionality.
This is a small patch that makes the autopilot work much better with big heavy
airliners as well as the small Cessnas. Of course this doesn't address the
way autopilots should be modeled.
But by making a couple changes the "George" is now capable of landing either a
C172 or a 747 very close to the center line of the runway with a moderate
cross breeze (15-20kt).
The changes:
- Added turn configurability so that things like Max Aileron and Roll can be
configured per aircraft.
- Enhanced localizer routine (NAV mode) to begin lining up the aircraft as soon
as the cone is entered. The former model is adopted for the last 5km of the
approach in order to ensure greater precision (makes a very slight difference).
[float cast added by David Megginson to keep G++ 3.0 happy]
This is a small patch that makes the autopilot work much better with big heavy
airliners as well as the small Cessnas. Of course this doesn't address the
way autopilots should be modeled.
But by making a couple changes the "George" is now capable of landing either a
C172 or a 747 very close to the center line of the runway with a moderate
cross breeze (15-20kt).
The changes:
- Added turn configurability so that things like Max Aileron and Roll can be
configured per aircraft.
- Enhanced localizer routine (NAV mode) to begin lining up the aircraft as soon
as the cone is entered. The former model is adopted for the last 5km of the
approach in order to ensure greater precision (makes a very slight difference).
[float cast added by David Megginson to keep G++ 3.0 happy]
1. Typo where /environment/density-inhg instead of
/environment/density-slugft3 was flagged as archivable.
2. Density should no longer be archivable anyway, since it is
calculated internally and not directly settable by the user.
temperature, and dewpoint. The /environment/density-sea-level-slugft3
property has been removed, and the /environment/density-slugft3
property is read-only.
Fetch all pending remote fdm network packets so there is not chance of
getting behind.
Add support for driving control panel lights.
Working on better modeling KX 155 tuning behavior.
won't apply the right gross weight due to fuel differences.
When solving for zero force, do so in the global frame, not the
aircraft's. In principle, this shouldn't matter (zero is zero in all
frames), but in practice this should help to avoid oscillations.
Calculating lift as force perpendicular to the ground (and not the
wing plane) is clearly the Right Thing, anyway.
Also added support for a /yasim/gross-weight-lbs property, which
should be generically useful.
when the lift/drag are really solid. And defer the approach trim until
the all four of the other variables are perfect. I believe this should
fix the solution failures under gcc 2.95.2.
implicitly in PropEngine by disallowing negative torques, but that was
removed at some point. We really need the explosion protection here
at the source.
This patch adds "elapsed time" support to the sound code.
It is now possible to define <internal>dt_play</internal> or
<internal>dt_stop</internal> instead of a propery in the <volume> and
<pitch> sections of the configuration file.
This is a small fix for what turned out to be a major bug. Ground elevation
was calculated incorrectly when distant from one of the view locations. This
resulted in several problems including bizarre gear trimming, mid air
"crashes" (as in thinking we hit the ground) and so on when close to or on the
ground.
Unfortunately it does require a second ssg traversal when in tower view
(only), but the increased load isn't all that noticable. For the time being
this really is the best solution. In a future update I will be eliminating
the unecessary per frame traversals for the static views (without having to
maintain multiple ssgRoots).
When we go to multiple FDM instances we will perhaps need to put the ssg
traversal and ground elevation queries for the FDMs into an event timer that
updates the FDMs ground elevation in a round robin fashion (maybe every 1/n
seconds where n is the number of FDM instances running).
layers. The properties controlling each layer are inside
/environment/clouds/layer[n], and the available properties are type
("clear", "overcast", "mostly-cloudy", "mostly-sunny", or "cirrus"),
span-m (should be about 40000), elevation-ft, thickness-ft, and
transition-ft.
This is a new improved patch for the previous tile manager fixes.
Rather than building dependencies between FGlocation or the viewer or fdm with
tilemgr what I ended up doing was linking the pieces together in the Mainloop
in main.cxx. You'll see what I mean...it's been commented fairly well. More
than likely we should move that chunk somewhere...just not sure where yet.
The changes seem clean now. As I get more ideas there could be some further
improvement in organizing the update in tilemgr. You'll note that I left an
override in there for the tilemgr::update() function to preserve earlier
functionality if someone needs it (e.g. usage independent of an fdm or
viewer), not to mention there are a few places in flightgear that call it
directly that have not been changed to the new interface (and may not need to be).
The code has been optimized to avoid duplicate traversals and seems to run
generally quite well. Note that there can be a short delay reloading tiles
that have been dropped from static views. We could call the tile scheduler on
a view switch, but it's not a big deal and at the moment I'd like to get this
in so people can try it and comment on it as it is.
Everything has been resycned with CVS tonight and I've included the
description submitted earlier (below).
Best,
Jim
Changes synced with CVS approx 20:30EDT 2002-05-09 (after this evenings updates).
Files:
http://www.spiderbark.com/fgfs/viewer-update-20020516.tar.gz
or
http://www.spiderbark.com/fgfs/viewer-update-20020516.diffs.gz
Description:
In a nutshell, these patches begin to take what was one value for ground
elevation and calculate ground elevation values seperately for the FDM and the
viewer (eye position). Several outstanding view related bugs have been fixed.
With the introduction of the new viewer code a lot of that Flight Gear code
broke related to use of a global variable called "scenery.cur_elev".
Therefore the ground_elevation and other associated items (like the current
tile bucket) is maintained per FDM instance and per View. Each of these has a
"point" or location that can be identified. See changes to FGLocation class
and main.cxx.
Most of the problems related to the new viewer in terms of sky, ground and
runway lights, and tower views are fixed.
There are four minor problems remaining. 1) The sun/moon spins when you pan
the "lookat" tower view only (view #3). 2) Under stress (esp. magic carpet
full speed with max visibility), there is a memory leak in the tile caching
that was not introduced with these changes. 3) I have not tested these
changes or made corrections to the ADA or External FDM interfaces. 4) The
change view function doesn't call the time/light update (not a problem unless
a tower is very far away).
Details:
FDM/flight.cxx, flight.hxx - FGInterface ties to FGAircraftModel so that it's
location data can be accessed for runway (ground elevation under aircraft)
elevation.
FDM/larsim.cxx, larcsim.hxx - gets runway elevation from FGInterface now.
Commented out function that is causing a namespace conflict, hasn't been
called with recent code anyway.
FDM/JSBSim/JSBSim.cxx, YASim/YASim.cxx - gets runway elevation from
FGInterface now.
Scenery/newcache.cxx, newcache.hxx - changed caching scheme to time based
(oldest tiles discard).
Scenery/tileentry.cxx, tileentry.hxx - added place to record time, changed
rendering to reference viewer altitude in order to fix a problem with ground
and runway lights.
Scenery/tilemgr.cxx, tilemgr.hxx - Modified update() to accept values for
multiple locations. Refresh function added in order to periodically make
the tiles current for a non-moving view (like a tower).
Main/fg_init.cxx - register event for making tiles current in a non-moving
view (like a tower).
Main/location.hxx - added support for current ground elevation data.
Main/main.cxx - added second tilemgr call for fdm, fixed places where viewer
position data was required for correct sky rendering.
Main/options.cxx - fixed segfault reported by Curtis when using --view-offset
command line parameter.
Main/viewer.cxx, viewer.hxx - removed fudging of view position. Fixed numerous
bugs that were causing eye and target values to get mixed up.
the wrong place. The Atmosphere::getStd*() calls are used by the
solver, and thus really need to return values for a "standard"
atmosphere. Otherwise, an aircraft started up in Moscow will behave
differently than one initialized in Cairo. :)
The place where environmental pressure and temperature get inspected
at runtime is in YASim.cxx. The changes there, happily, end up being
even smaller than the ones to Atmosphere. This ends up replacing code
only, and removing some comments.
Here is the new super improved telnet property interface. CVS changelog
is at the end of this message. Once this new telnet code is in and
compiles every where we can remove Network/props.[ch]xx. I've added a
--telnet=<port> command line option to invoke the new server. Later on
we could remove the --props option, or least change it to invoke the new
server. I'll let you decide.
I've added some new commands to the telnet interface:
view next Select the next view.
view prev Select the previous view.
view set <n> Select view 'n'
view get Return index of current view
I'm not sure if these same effects could be achieved through property
operations. The commands provide a convenient shortcut in any case.
I'm also planning on adding a panel command to manipulate panels and
objects contained therein (eg simulated mouse clicks). There is going
to be some commonality with the command objects so we may need to
rationalize this in the near future.
Finally, I've also included my python stuff. This is still very much a
work in progress, basically I've been using it to test the new telnet
server. I have tested it with python 2.2. Feel free to add it to the
repository if you want. I would suggest a scripts/python directory
CVS Changelog
Network/telnet.cxx: New property telnet protocol interface. It supports
the same user interface provided by the --props server. Additionally it
handles multiple simultaneous connections. Added "view" command to
manipulate viewmgr.
Network/protocol.hxx: Added protocol configuration exception.
Main/fg_io.cxx: Added new "telnet" protocol. Added protocol
configuration parse exceptions. Simplified protocol configuration
parsing.
Main/options.cxx: Added --telnet=<port> command line option and help
message.
set_Density; since JSBSim doesn't override the get_* methods from
FGInterface as well, the wrong values are always set anyway.
Take the static temperature, static pressure, and density values from
an external source if requested by the
/environment/params/control-fdm-atmosphere property. This isn't
working properly yet for JSBSim because of interactions with the
trimming routine.
Stratosphere). The atmospheric properties are as follow:
/environment/temperature-sea-level-degc
/environment/temperature-degc
/environment/pressure-sea-level-inhg
/environment/pressure-inhg
/environment/density-sea-level-slugft3
/environment/density-slugft3
Setting either the sea-level or altitude value automatically sets the
other value appropriate, except for temperature at altitude above the
Troposphere (where there's no reliable way to back-calculate it). The
atmosphere model appears in the atmosphere_data array in
environment.cxx, and can easily be extended into the upper
stratosphere and beyond.
These are not yet tied into the FDMs or steam module.
Removed configuration option --with-new-environment and
FG_NEW_ENVIRONMENT macro.
Added configuration option --with-weathercm and FG_WEATHERCM macro.
FGEnvironment is now the default; use --with-weathercm to get the old
weather.
object rather than a pointer.
FGEnvironment now has the beginning of an atmospheric model, and will
recalculate temperature (not pressure or density, yet) based on
elevation.
FGEnvironment has a copy constructor.
- changed FGSubsystem::update(int) to
FGSubsystem::update(delta_time_sec); the argument is now delta time
in seconds rather than milliseconds
- added FGSubsystem::suspend(), FGSubsystem::suspend(bool),
FGSubsystem::resume(), and FGSubsystem::is_suspended(), all with
default implementations; is_suspended takes account of the master
freeze as well as the subsystem's individual suspended state
- the FDMs now use the delta time argument the same as the rest of
FlightGear; formerly, main.cxx made a special case and passed a
multiloop argument
- FDMs now calculate multiloop internally instead of relying on
main.cxx
There are probably some problems -- I've done basic testing with the
major FDMs and subsystems, but we'll probably need a few weeks to
sniff out bugs.
The FlightGear patch is to take account the change in the getChildren
function that now returns a vector<SGPropertyNode_ptr>. If the
removeChild functionnality is to be added in FlightGear, all those
SGPropertyNode * floating around should be changed to
SGPropertyNode_ptr.
- don't send "set" confirmation when in data mode. If an external
program really cares if the settings were accepted, which is
rather unlikely, it simply has to "get" the property again.
The returned line would have been a pain to parse, anyway
(something like "from-model = 'true' (bool)").
- do not only "set" the first token, but concatenate all given
tokens with a space in between. This won't be used much, but
makes sense for setting strings, while it does no harm when setting
numbers. Silently ignoring all but the first token is impolite. ;-)
- remove old, commented out debug message that doesn't make much
sense any more.
Due to jumpy joystick read-outs the UFO jitters a lot in turns.
This patch implements simple damping for aileron/elevator/throttle.
Furthermore it lets the UFO fly backwards if brake[0] is active
(by default associated with the joystick's fire button). After all,
everyone knows that UFO's can fly backwards!
It's cumbersome to use the MagicCarpet as 3D cursor, because everytime
you shoot over the target you have first to turn by 180 degrees and to
fly back.
This patch lets the magic carpet fly backwards if brake[0] is active,
which is by default associated with the joystick's fire button.
Turns out it was a problem with a long string, not the font. Plib is limited
to 80 characters in things like this listbox. BTW I checked and all the fonts
are missing those characters. So, no point in changing.
Description:
Fixed segfault caused by long string.
> I have attached some new additions to the UIUC code. Most of the
> changes allow for the addition of apparent mass. This is very
> useful with light aircraft and gliders.
I changed the sound code to let it use FGCondition. This changes the
code and configuration files rather drastically. Furthermore I've added
an in-transit mode which plays the sound only when the tied property is
changing.
Changes:
Code:
* Added condition support to trigger an event
* Removed the <type> section from the main event definition
(this could be done using conditions)
* Removed the abillity to use several events with the same name,
instead it is required to use conditions.
* Updated the README.xmlsound
Base package:
* Changed the configuration files accordingly.
* Changed flaps and gear to use the new in-stransit mode.
* Changed the flps.wav file so it can be looped.
* Created a new gear.wav file (whcih can be looped)
and a gear-lck.wav file for gear locking sound.
IMPORTANT:
To change existing configuration files to the new ones, it is important
to pack events with the same name together into one singel event, using
the condition specification. Also, when using special types (inverted,
flip-flop, raise or fall) these should be changed to a conditions also.
For more information, please look at
FLightGear/docs-mini/README.xmlsound and the supplied aircraft
configuration files located under FlightGear/Aircraft (espesially
c172/c172-sound.xml and c310/c310-sound.xml).
default implementation that uses user-supplied params. Currently, the
only parameters are
/environment/params/base-wind-speed-kt
/environment/params/gust-wind-speed-kt
but others will show up soon (i.e. sheer, variable direction, variable
visibility, etc.). To activate these properties, you have to
configure --with-new-environment.
The gusting function is simplistic and needs to be replaced with
something better, though it doesn't feel too far off.
subproperty, 'spherical', which is true if the object has spherical
symmetry and should rotate around both the x-axis and z-axis to face
the camera (i.e. a simple cloud), and false if the object has only
cylindrical symmetry and should rotate only around the z-axis (i.e. a
tree).
1. If /position/longitude-deg and /position/latitude-deg are in range,
use them.
2. Otherwise, if /sim/startup/airport-id is not empty, use it.
3. Otherwise, set the lon/lat to the middle of the KSFO field.
The default used to be Globe, AZ, but that doesn't make sense since we
don't distribute that scenery by default any more.
With this change, starting from a save file seems to work properly:
fgfs myflight.sav
- Added initial_value argument, in milliseconds, that specifies when
event is first run. The default value of -1 triggers the event
immediately as per the existing behaviour. A repeat_value greater than
zero runs the event no less than every 'repeat_value' milliseconds
afterwards. A repeat_value of zero deletes the event.
- Modified run queue behaviour such that only one event per frame is
run.
ATCmgr.cxx:148 says:
// Returns true if the airport is found in the map
Yes, it returns true if the airport has been found. But it fails
to return the airport data. Just plays around with a local pointer. ;-)
I have finished working the bugs out of my "Enhanced" version of the Magic
Carpet FDM. The UFO FDM works the same as the Magic Carpet with the
following exceptions:
The aircraft's pitch is determined by the Elevator setting (with a pitch
rate of 45 degrees per second).
Climb is forward velocity * sin(pitch)
Speed is forward velocity * soc(pitch)
Roll is tied to the aileron (again, with a roll rate of 45 degrees per
second)
Turn rate is sin(roll) * 45 degrees.
Yes, this does mean that turning is quite a bit more sluggish than
climbing.
If you are wondering why a UFO FDM, it is because it's best that I not
replace the existing magic carpet and this FDM does behave like a UFO (it
hovers, can spin and pitch while hovering, and does not obey the laws of
physics ;)
