76 lines
2.4 KiB
Text
76 lines
2.4 KiB
Text
|
Logging in FlightGear
|
||
|
|
---------------------
|
||
|
|
|
||
|
|
[Note: JSBSim also has its own independent logging facilities, which
|
||
|
|
are not discussed here.]
|
||
|
|
|
||
|
|
FlightGear can log any property values at any interval to one or more
|
||
|
|
CSV files (which can be read and graphed using spreadsheets like
|
||
|
|
Gnumeric or Excel). Logging is defined in the '/logging' subbranch of
|
||
|
|
the main property tree; under '/logging', each '/log' subbranch
|
||
|
|
defines a separate log with its own output file and interval. Here is
|
||
|
|
a simple example that logs the rudder and aileron settings every
|
||
|
|
second (1000ms) to the file steering.csv:
|
||
|
|
|
||
|
|
<logging>
|
||
|
|
<log>
|
||
|
|
<filename>steering.csv</filename>
|
||
|
|
<interval-ms>1000</interval-ms>
|
||
|
|
<entry>
|
||
|
|
<title>Rudder</title>
|
||
|
|
<property>/controls/rudder</property>
|
||
|
|
</entry>
|
||
|
|
<entry>
|
||
|
|
<title>Ailerons</title>
|
||
|
|
<property>/controls/aileron</property>
|
||
|
|
</entry>
|
||
|
|
</log>
|
||
|
|
</logging>
|
||
|
|
|
||
|
|
Each 'log' subbranch contains an optional 'filename' property
|
||
|
|
(defaults to "fg_log.csv"), an optional 'interval-ms' property
|
||
|
|
(defaults to 0, which logs every frame), and a series of 'entry'
|
||
|
|
subbranches.
|
||
|
|
|
||
|
|
Each 'entry' subbranch contains a 'property' property specifying the
|
||
|
|
name of the property to be logged, and an optional 'title' property
|
||
|
|
specifying the title to use in the CSV file (defaults to the full path
|
||
|
|
of the property). The elapsed time in milliseconds since the start of
|
||
|
|
the simulation is always included as the first entry with the title
|
||
|
|
"Time", so there is no need to include it explicitly.
|
||
|
|
|
||
|
|
Here's a sample of the logging output for the above log:
|
||
|
|
|
||
|
|
Time,Rudder,Ailerons
|
||
|
|
6522,0.000000,0.000000
|
||
|
|
7668,-0.000000,0.000000
|
||
|
|
8702,-0.000000,0.000000
|
||
|
|
9705,-0.000000,0.000000
|
||
|
|
10784,-0.000000,0.000000
|
||
|
|
11792,-0.000000,0.000000
|
||
|
|
12808,-0.000000,-0.210000
|
||
|
|
13826,-0.000000,-0.344000
|
||
|
|
14881,-0.000000,-0.066000
|
||
|
|
15901,-0.000000,-0.806000
|
||
|
|
16943,-0.000000,-0.936000
|
||
|
|
17965,-0.000000,-0.534000
|
||
|
|
19013,-0.000000,-0.294000
|
||
|
|
20044,-0.000000,0.270000
|
||
|
|
21090,-0.000000,-1.000000
|
||
|
|
22097,-0.000000,-0.168000
|
||
|
|
|
||
|
|
Note that the requested interval is only a minimum; most of the time,
|
||
|
|
the actual interval is slightly longer than the requested one.
|
||
|
|
|
||
|
|
The easiest way for an end-user to define logs is to put the log in a
|
||
|
|
separate XML file (usually under the user's home directory), then
|
||
|
|
refer to it using the --config option, like this:
|
||
|
|
|
||
|
|
fgfs --config=log-config.xml
|
||
|
|
|
||
|
|
The output log files are always relative to the current directory.
|
||
|
|
|
||
|
|
--
|
||
|
|
|
||
|
|
David Megginson, 2002-03-12
|