Writing Joystick Code: Part 2

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Code snippets

Make sure you have read Input device and Writing Joystick Code: Part 1 first.

Code snippets are what you use instead of Your code goes here and Ctrl-Alt button released as seen in Part 1. You just need to put them in the right place - in between the <script> and </script> tags.

Please note that some of them have concepts that will be explained in Part 3.

Each snippet has the following format:

Action R/NR S C
   Code for action
   Code for <mod-up>

Where Action is what you want to do, R means use with a repeatable button, NR means use with a non-repeatable button, and U is the code for <mod-up>. If it is not there, a <mod-up> is not needed.

An S, if present, means that it is a step action. gearDown is not a step-action, the gear is either up or down. flapsDown is a step action. Each time you send a flapsDown command the flaps go down one notch. This matters not if you are using a non-repeatable button, but if you use a repeating button, as long as you are pressing the button, flapsDown commands are being sent. This means that if you are still pressing the button when the flaps reach the next notch, they will go down one more notch.

The C, if present, means that whatever is being controlled is continously variable between its limits. An example is elevator trim. It moves between full-down to full-up in very tiny steps. Very tiny.

Some Actions will have code for use with repeatable and non-repeatable buttons. Sometimes it is not wise to use the wrong type for a certain action. And sometimes you must use the correct type for an action - using a non-repeating button for Zoom is a bad idea, the user will have to constantly keep triggering the button to reach the zoom level he requires. Using a repeatable button is possible for something like gearDown, as long as the use knows to just use a brief push, but it is a bad idea.

Notice that some commands have a +1 or a -1 in brackets to specify the direction of the action, and a 0 to say stop doing that. The 0 version will of course be in the <mod-up> section.

If the action is upside-down for you, swap the + and - signs.

Also, sometimes the 1 is replaced by a number, which specifies by how much the action should be carried out. This is of course not approprite for all actions - you would not want to lower the gear just 75% of the way. If the action is too vicious for you, make the number smaller.

The snippets

Gear down NR

Gear up NR

Flaps down one notch NR S

Flaps up one notch NR S

Deploy spoilers NR S

Retract spoilers NR S

Cycle View NR

Elevator trim down R C

Elevator trim up R C

Elevator Trim down NR C
   interpolate("/controls/flight/elevator-trim", 1, 30 * (1 - getprop("controls/flight/elevator-trim")))
   interpolate("/controls/flight/elevator-trim", getprop("controls/flight/elevator-trim"), 0)

Elevator trim up NR C
   interpolate("/controls/flight/elevator-trim", -1, 30 * (1 - getprop("controls/flight/elevator-trim")))
   interpolate("/controls/flight/elevator-trim", getprop("controls/flight/elevator-trim"), 0)

To make it go faster, make the 30 smaller.

Aileron trim left R C

Aileron trim right R C

Aileron trim left NR C
   interpolate("/controls/flight/aileron-trim", -1, 30 * (1 - getprop("controls/flight/aileron-trim")))
   interpolate("/controls/flight/aileron-trim", getprop("controls/flight/aileron-trim"), 0)

Aileron trim right NR C
   interpolate("/controls/flight/aileron-trim", 1, 30 * (1 - getprop("controls/flight/aileron-trim")))
   interpolate("/controls/flight/aileron-trim", getprop("controls/flight/aileron-trim"), 0)

To make it go faster, make the 30 smaller.

If you want rudder-trim, use either the repeatable or non-repeatable above, changing elevator-trim/aileron-trim to rudder-trim.

Apply left brake NR
   controls.applyBrakes(1, -1)
   controls.applyBrakes(0, -1)

Apply Right brake NR
   controls.applyBrakes(1, 1)
   controls.applyBrakes(0, 1)

Start Stopwatch NR

Stop Stopwatch NR

Reset Stopwatch NR

Make mixture richer R C

Make mixture leaner R C

Start all engines R

Start specific engine R
   controls.startEngine(1, x)
   controls.startEngine(0, x)

x is the engine number. First engine is 0.


How this is implemented in each aircraft depends on the design of the aircraft. If it has predefined wingsweep settings it will step through these settings.
If not, it will step 20% of the way each time called.

Wingsweep forward NR
Wingsweep backwards NR
It is possible (but desirable?) to use any value from 1 to 5 in the brackets. This will make the wings sweep more steps at a time.


 Fire selected weapon NR

 Select previous weapon NR

 Select next weapon NR

Toggle all lights on/off NR

Switch specific lights on NR
  setProp(("controls/lighting/xxx"), true)

Switch specific lights off NR
  setProp(("controls/lighting/xxx"), false)

Where xxx = beacon, landing-lights, landing-light, landing-light[1] logo-lights, nav-lights, strobe, taxi-light,
taxi-lights, cabin-lights, map-lights. 

Instrument lights level brighter R
      if(getprop("controls/lighting/instruments-norm") < 1 ) {
         setprop("controls/lighting/instruments-norm", getprop ("controls/lighting/instruments-norm") + 0.05)

Instrument lights level dimmer R
      if(getprop("controls/lighting/instruments-norm") > 0 ) {
         setprop("controls/lighting/instruments-norm", getprop ("controls/lighting/instruments-norm") - 0.05)

Instrument lights level up NR
      if(getprop("controls/lighting/instruments-norm") < 1 ) {
         setprop("controls/lighting/instruments-norm", getprop ("controls/lighting/instruments-norm") + 0.2)

Instrument lights level down NR
      if(getprop("controls/lighting/instruments-norm") > 0 ) {
         setprop("controls/lighting/instruments-norm", getprop ("controls/lighting/instruments-norm") - 0.2)

Step magnetos up NR

Step magnetos down NR

While editing an xml file, if you find a line is too long for your page width, then you can press Enter and go to a new line. FG will be happy - it needs a tag or a ; at the end of a line to tell it that the current line of code is finished.

  setprop("controls/engines/engine/mixture", getprop ("controls/engines/engine/mixture") + 0.05)


      getprop ("controls/engines/engine/mixture") + 0.05)

Notice where I put the newline and how I indented the second line. Both are designed to make it easy for people to read, as part of being a programmer is making your code legible for others.

Any complaints/suggestions/questions/kudos can be posted here.

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