occasionally cause a large number of valid stations to be flagged as invalid.
This *seemed* like a "race condition" type problem because there were some
assumptions in the communication between the main process and the threaded
loader which if they broke down could lead to this problem.
In the process of removing this ambiguity, I restructured the threaded
(and non-threaded) metar fetching code a bit. Some of the top level logic
(which Erik politely left untouched) didn't make nearly as much sense in the
context of a threaded metar loader and could have contributed to some of the
wierdness I was seeing.
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>
are many recognized limitations and inefficiencies with this entire approach,
however, it's a quick and dirty way to get something working, where before
we didn't.
The last change from Curt to Airports/simple.[ch]xx made
GUI/AirportList.cxx not compilable because of the loss of
a '*' in getAirport.
Also : fabs is not defined under MSVC unless <math.h> is
included.
updates based on the "closest" airport with metar data available. Note that
the web based query is in the main loop and causes brief sim pauses. Update
rate (once per minute) needs to be tweaked with, but is a good value for
testing.
