Input device: Difference between revisions

Unfortunately, given the several combinations of operating systems supported by FlightGear (possibly in foreign languages) and joysticks available, chances are your joystick does not work out of the box. Basically, there are two alternative approaches to get it going, with the first one being preferred.

In order for joystick auto-detection to work, a joystick bindings xml file must exist for each joystick. This file describes what axes and buttons are to be used to control which functions in FlightGear. The associations between functions and axes or buttons are called “bindings”. This bindings file can have any name as long as a corresponding entry exists in the joysticks description file  

for a file that might work for your joystick. If such a file exists and your joystick is working with other applications, then it should work with FlightGear the first time you run it. If such a file does not exist, then we will discuss in a later section how to create such a file by cutting and pasting bindings from the examples that are included with FlightGear.

Does your computer see your joystick? One way to answer this question under Linux is to reboot your system and immediately enter on the [[command line]]  

This line tells us that a joystick has identified itself as SAITEK CYBORG 3D USB to the operating system. It does not tell us that the joystick driver sees your joystick. If you are working under Windows, the method above does not work. Go to <tt>Start > Controlpanel > Game Controller</tt> instead and see whether the dialog displays (and responses) on your joystick.  

FlightGear ships with a utility called js_demo. It will report the number of joysticks attached to a system, their respective “names”, and their capabilities. Under Linux, you can run js_demo from the folder /FlightGear/bin as follows:  

  js_demo.exe  

On our system, the first few lines of output are (stop the program with C if it is quickly scrolling past your window!) as follows:  

First note that js demo reports which number is assigned to each joystick recognized by the driver. Also, note that the “name” each joystick reports is also included between quotes. We will need the names for each bindings file when we begin writing the binding xml files for each joystick.

Axis and button numbers can be identified using js demo as follows. By observing the output of js demo while working your joystick axes and buttons you can determine what axis and button numbers are assigned to each joystick axis and button. It should be noted that numbering generally starts with zero.  

When you move any control, the numbers change after the axis number corresponding to that moving control and when you depress any button, the “off” after the button number corresponding to the button pressed changes to “on”. In this way, you can quickly write down the axes numbers and button numbers for each function without messing with binary.

At this point, you have confirmed that the operating system and the joystick driver both recognize your joystick(s). You also know of several ways to identify the joystick “name” your joystick reports to the driver and operating system. You will need a written list of what control functions you wish to have assigned to which axis and button and the corresponding numbers.  

Several users have reported that the numbers of axes and buttons assigned to functions may be different with the same joystick under Windows and Linux. The above procedure should allow one to easily change a binding xml file created for a different operating system for use by their operating system.

Before FlightGear can use your new xml file, you need to edit the file  

You can tell how FlightGear has interpretted your joystick setup by selecting Help -> Joystick Information from the Menu.

Basically, the procedures described above should work for Windows as well. If your joystick/yoke/pedals work out of the box or if you get it to work using the methods above, fine. Unfortunately there may be a few problems.  

Unfortunately, we did not find a way to get the pedals to work, too, that way. Thus, in cases like this one (and others) you may want to try an alternative method of assigning joystick controls.

Fortunately, there is a tool available now, which takes most of the burden from the average user who, maybe, is not that experienced with XML, the language which these files are written in.  

You should be able to at least get your joystick working along these lines. Concerning all the finer points, for instance, getting the joystick buttons working, John Check has written a very useful README being included in the base package to be found under '''FlightGear/Docs/Readme/Joystick.html'''. In case of any trouble with your input device, it is highly recommended to have a look into this document.

  & < --

* If your scripts contain any of these characters, you have to enclose the scripts in <script><![CDATA[...]]></script>. Alternatively, you can 'escape' the characters, ie "<" becomes "&lt;".

** A guide to the [[Nasal scripting language]] in FlightGear  

** [[Nasal FAQ]]

* All Nasal code shares a common namespace, so it's possible to set a variable in one nasal binding, and to read it in another.

Some particularly useful ideas for programming scripts within joystick XML files:

* getprop and setprop can be used for getting & setting properties from the internal properties tree:

  print("Just", " a ", "test");

  gui.popupTip("Parking Brake ON");

Note that "var" creates variables that are local in scope, which may cause problems if you are intending to use a variable globally among all different bindings in your joystick XML file.

  <PropertyList>

   <name type="string">My joystick name</name>

* Sample code for firing weapons with the joystick is found on the [[Gun Effects]] page.

* [http://www.flightgear.org/Docs/getstart/getstartch3.html#x8-360003.6 The FlightGear Manual]

== External Links ==