8506e731a2
All logs and log entries are now disabled by default, unless explicitly enabled by an 'enabled' property. This works much more intuitively with the GUI dialog.
86 lines
3 KiB
Text
86 lines
3 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, using a comma (the default,
|
|
anyway) as the field delimiter:
|
|
|
|
<logging>
|
|
<log>
|
|
<enabled>true<enabled>
|
|
<filename>steering.csv</filename>
|
|
<interval-ms>1000</interval-ms>
|
|
<delimiter>,</delimiter>
|
|
<entry>
|
|
<enabled>true</enabled>
|
|
<title>Rudder</title>
|
|
<property>/controls/rudder</property>
|
|
</entry>
|
|
<entry>
|
|
<enabled>true</enabled>
|
|
<title>Ailerons</title>
|
|
<property>/controls/aileron</property>
|
|
</entry>
|
|
</log>
|
|
</logging>
|
|
|
|
Each 'log' subbranch contains a required 'enabled' property, an
|
|
optional 'filename' property (defaults to "fg_log.csv"), an optional
|
|
'delimiter' property (defaults to a comma), an optional 'interval-ms'
|
|
property (defaults to 0, which logs every frame), and a series of
|
|
'entry' subbranches. The 'delimiter' property uses only the first
|
|
character of the property value as the delimiter. Note that the
|
|
logger does no escaping, so you must choose a delimiter that will not
|
|
appear in the property values (that's not hard, since most of the
|
|
values are numeric, but watch for commas in the titles).
|
|
|
|
Each 'entry' subbranch contains a required 'enabled' property, 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, last updated 2002-02-01
|