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.
(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.
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 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.
- 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.
for fuselage Surface objects. If the fuselage wasn't aligned perpendicular
to the Y axis, the matrix wouldn't be orthonormal. Since all of, perhaps,
three aircraft have ever been built this way, it's doubtful I would have
found this as a bug report. :)
and scaling of control values to properties. Also added a time interpolation
feature that replaces the hacked-in "retract-time" feature for the gear in
a more general way (applicable to flaps, too!). Incompatibly breaks
the XML syntax; get new files!
properties have been renamed from wind-(north|east|down)-fps to
wind-from-(north|east|down)-fps, and the FDMs modified appropriately.
No other changes should be visible unless FG_OLD_WEATHER is defined.
FDM people. FlightGear now supports an unlimited number of fuel
tanks. Also added correct fuel-flow reporting for piston engines, and
tracked new features in SimGear property support.
- automake-1.4 sets default values for INCLUDES which we can't
overwrite.
- automake-1.5 renames this to DEFAULT_INCLUDES and leaves INCLUDES
open for the developer to use.
Thus for automake-1.4 we are forced to 'append' to INCLUDES and in
automake-1.5 we can just set the value to whatever we like.
Unfortunately, the behaviors of the two versions are mutually
incompatible.
The solution I am committing now works for both versions but
automake-1.5 generates a lot of spurious warning messages that are
annoying, but not fatal.
(i.e. multiloop). Most subsystems currently ignore the parameter, but
eventually, it will allow all subsystems to update by time rather than
by framerate.
Here's an unusual patch for FlightGear -- I've created .cvsignore
files for every source directory, to make CVS output more informative.
This is especially nice when using cvs-examine from (X)Emacs to look
for changes.
Note there is still a problem when doing a 'reset' after doing
a 'goto'. Curt says: I also see that doing two subsequent reset's on a
JSBSim model results in a segfault in a deconstructor deep inside JSBSim.
Dynamics (Sim)ulator. Basically, this is a rough, first cut of a "different
take" on FDM design. It's intended to be very simple to use,
producing reasonable results for aircraft of all sorts and sizes,
while maintaining simulation plausibility even in odd flight
conditions like spins and aerobatics. It's at the point now where one
can actually fly the planes around.
