655 lines
26 KiB
Plaintext
655 lines
26 KiB
Plaintext
Users Guide to FlightGear panel configuration
|
|
Version 0.7.7, May 16 2001
|
|
Author: John Check <j4strngs@rockfish.net>
|
|
|
|
This document is an attempt to describe the configuration of
|
|
FlightGear flight simulator's aircraft panel display via XML. The
|
|
information was culled from the fgfs-devel@flightgear.org mailing list
|
|
and my experiences making alternate panels. Corrections and additions
|
|
are encouraged.
|
|
|
|
Some History:
|
|
------------
|
|
Older versions of FGFS had a hard coded display of instruments. This
|
|
was a less than ideal state of affairs due to FGFS ability to use
|
|
different aircraft models. Being primarily developed on UNIX type
|
|
systems, a modular approach is taken towards the simulation. To date,
|
|
most alternatives to the default Cessna 172 aircraft are the product
|
|
of research institutions interested in the flight characteristics and
|
|
not cosmetics. The result of this was that one could fly the X-15 or
|
|
a Boeing 747 but be limited to C172 instrumentation.
|
|
|
|
A rewrite of the panel display code was done around v0.7.5 by
|
|
developer David Megginson allowing for configuration of the panel via
|
|
XML to address this limitation. Some major changes and additions were
|
|
made during the course of version 0.7.7 necessitating a rewrite and
|
|
expansion of this document.
|
|
|
|
|
|
About The Property Manager:
|
|
--------------------------
|
|
While not absolutely necessary in order to create aircraft panels,
|
|
some familiarity with the property manager is beneficial....
|
|
FlightGear provides a hierarchical representation of all aspects of
|
|
the state of the running simulation that is known as the property
|
|
tree. Some properties, such as velocities are read only. Others such
|
|
as the frequencies to which the navcom radios are tuned or the
|
|
position of control surfaces can be set by various means. FlightGear
|
|
can optionally provide an interface to these properties for external
|
|
applications such as Atlas, the moving map program, or even lowly
|
|
telnet, via a network socket. Data can even be placed on a serial port
|
|
and connected to, say a GPS receiver. Aside from its usefulness in a
|
|
flight training context, being able to manipulate the property tree on
|
|
a running copy of FG allows for switching components on the fly, a
|
|
positive boon for panel authors. To see the property tree start FG
|
|
with the following command line:
|
|
|
|
fgfs --props=socket,bi,5,localhost,5500,tcp
|
|
|
|
Then use telnet to connect to localhost on port 5500. You can browse
|
|
the tree as you would a filesystem.
|
|
|
|
XML and the Property Manager:
|
|
----------------------------
|
|
Panel instruments interface with the property tree to get/set values
|
|
as appropriate. Properties for which FG doesn't yet provide a value
|
|
can be created by simply making them up. Values can be adjusted using
|
|
the telnet interface allowing for creation and testing of instruments
|
|
while code to drive them is being developed.
|
|
|
|
If fact, the XML configuration system allows a user to combine
|
|
components such as flight data model, aircraft exterior model, heads
|
|
up display, and of course control panel. Furthermore, such a
|
|
preconfigured aircraft.xml can be included into a scenario with
|
|
specific flight conditions. These can be manually specified or a FG
|
|
session can be saved and/or edited and reloaded later. Options
|
|
specified in these files can be overridden on the command line. For
|
|
example:
|
|
|
|
--prop:/sim/panel/path=Aircraft/c172/Panels/c172-panel.xml
|
|
|
|
passed as an option, would override a panel specified elsewhere.
|
|
Property tree options all have the same format, specify the node and
|
|
supply it a value.
|
|
|
|
The order of precedence for options is thus:
|
|
|
|
Source Location Format
|
|
------ -------- ------
|
|
command line
|
|
.fgfsrc Users home directory. command line options
|
|
system.fgfsrc $FG_ROOT "" ""
|
|
preferences.xml $FG_ROOT XML property list
|
|
|
|
|
|
Loading Panels on the fly:
|
|
-------------------------
|
|
When editing a panel configuration, pressing Shift +F3 will reload the
|
|
panel. If your changes don't seem to be taking effect, check the
|
|
console output. It will report the success or failure of the panel
|
|
reload*. Editing textures requires restarting FGFS so the new textures
|
|
can be loaded. Panels can be switched on the fly by setting the
|
|
/sim/panel/path property value and reloading.
|
|
|
|
Regarding Window Geometry:
|
|
-------------------------
|
|
For the sake of simplicity the FGFS window is always considered to be
|
|
1024x768 so all x/y values for instrument placement should relative to
|
|
these dimensions. Since FG uses OpenGL 0,0 represents the lower left
|
|
hand corner of the screen. Panels may have a virtual size larger than
|
|
1024x768. Vertical scrolling is accomplished with
|
|
Shift+F5/F6. Horizontal scrolling is via Shift+F7/F8. An offset should
|
|
be supplied to set the default visible area. It is possible to place
|
|
items to overlap the 3D viewport.
|
|
|
|
Panel Architecture:
|
|
-------------------
|
|
All of the panel configuration files are XML-encoded* property lists.
|
|
The root element of each file is always named <PropertyList>. Tags are
|
|
almost always found in pairs, with the closing tag having a slash
|
|
prefixing the tag name, i.e </PropertyList>. The exception is the tag
|
|
representing an aliased property. In this case a slash is prepended to
|
|
the closing angle bracket. (see section Aliasing)
|
|
|
|
The top level panel configuration file is composed of a <name>, a
|
|
<background> texture and zero or more <instruments>.Earlier versions
|
|
required instruments to have a unique name and a path specification
|
|
pointing to the instruments configuration file.
|
|
|
|
[ Paths are relative to $FG_ROOT (the installed location of FGFS data files.) ]
|
|
[ Absolute paths may be used.Comments are bracketed with <!-- -->. ]
|
|
|
|
Old style instrument call in top level panel.xml:
|
|
------------------------------------------------
|
|
<clock> <!-- required "unique_name" -->
|
|
<path>Aircraft/c172/Instruments/clock.xml</path>
|
|
<x>110</x> <!-- required horizontal placement -->
|
|
<y>320</y> <!-- required vertical placement -->
|
|
<w>72</w> <!-- optional width specification -->
|
|
<h>72</h> <!-- optional height specification -->
|
|
</clock>
|
|
|
|
The difference between the old and new styles, while subtle, is rather
|
|
drastic. The old and new methods are indeed incompatible. I cover the
|
|
old style only to acknowledge the incompatibility. This section will
|
|
be removed after the next official FGFS release.
|
|
|
|
New Style Example Top Level Panel Config:
|
|
----------------------------------------
|
|
<PropertyList>
|
|
<name>Example Panel</name>
|
|
<background>Aircraft/c172/Panels/Textures/panel-bg.rgb</background>
|
|
<w>1024</w> <!-- virtual width -->
|
|
<h>768</h> <!-- virtual height -->
|
|
<y-offset>-305</y-offset> <!-- hides the bottom part -->
|
|
<view-height>172</view-height> <!-- amount of overlap between 2D panel and 3D viewport -->
|
|
|
|
<instruments> <!-- from here down is where old and new styles break compatibility -->
|
|
|
|
<instrument include="../Instruments/clock.xml">
|
|
<name>Chronometer</name> <!-- currently optional but strongly recommended -->
|
|
<x>150</x> <!-- required horizontal placement -->
|
|
<y>645</y> <!-- required vertical placement -->
|
|
<w>72</w> <!-- optional width specification -->
|
|
<h>72</h> <!-- optional height specification -->
|
|
</instrument>
|
|
|
|
</instruments>
|
|
|
|
</PropertyList>
|
|
|
|
|
|
Indexed Properties
|
|
------------------
|
|
This is a lot to do with the compatibility break so lets get it out of
|
|
the way. The property manager now assigns incremental indices to
|
|
repeated properties with the same parent node, so that
|
|
|
|
<PropertyList>
|
|
<x>1</x>
|
|
<x>2</x>
|
|
<x>3</x>
|
|
</PropertyList>
|
|
|
|
shows up as
|
|
|
|
/x[0] = 1
|
|
/x[1] = 2
|
|
/x[2] = 3
|
|
|
|
This means that property files no longer need to make up a separate
|
|
name for each item in a list of instruments, layers, actions,
|
|
transformations, or text chunks. In fact, the new panel I/O code now
|
|
insists that every instrument have the XML element name "instrument",
|
|
every layer have the name "layer", every text chunk have the name
|
|
"chunk", every action have the name "action", and every transformation
|
|
have the name "transformation" -- this makes the XML more regular (so
|
|
that it can be created in a DTD-driven tool) and also allows us to
|
|
include other kinds of information (such as doc strings) in the lists
|
|
without causing confusion.
|
|
|
|
Inclusion:
|
|
----------
|
|
The property manager now supports file inclusion and aliasing.
|
|
Inclusion means that a node can include another property file as if it
|
|
were a part of the current file. To clarify how inclusion works,
|
|
consider the following examples:
|
|
|
|
If bar.xml contains
|
|
|
|
<PropertyList>
|
|
<a>1</a>
|
|
<b>
|
|
<c>2</c>
|
|
</b>
|
|
</PropertyList>
|
|
|
|
then the declaration
|
|
|
|
<foo include="../bar.xml">
|
|
</foo>
|
|
|
|
is exactly equivalent to
|
|
|
|
<foo>
|
|
<a>1</a>
|
|
<b>
|
|
<c>2</c>
|
|
</b>
|
|
</foo>
|
|
|
|
However, it is also possible to selectively override properties in the
|
|
included file. For example, if the declaration were
|
|
|
|
<foo include="../bar.xml">
|
|
<a>3</a>
|
|
</foo>
|
|
|
|
then the property manager would see
|
|
|
|
<foo>
|
|
<a>3</a>
|
|
<b>
|
|
<c>2</c>
|
|
</b>
|
|
</foo>
|
|
|
|
with the original 'a' property's value replaced with 3.
|
|
|
|
This new inclusion feature allows property files to be broken up and
|
|
reused arbitrarily -- for example, there might be separate cropping
|
|
property lists for commonly-used textures or layers, to avoid
|
|
repeating the information in each instrument file.
|
|
|
|
|
|
Aliasing
|
|
--------
|
|
Properties can now alias other properties, similar to a symbolic link
|
|
in Unix. When the target property changes value, the new value will
|
|
show up in the aliased property as well. For example,
|
|
|
|
<PropertyList>
|
|
<foo>3</foo>
|
|
<bar alias="/foo"/>
|
|
</PropertyList>
|
|
|
|
will look the same to the application as
|
|
|
|
<PropertyList>
|
|
<foo>3</foo>
|
|
<bar>3</bar>
|
|
</PropertyList>
|
|
|
|
except that when foo changes value, bar will change too.
|
|
|
|
|
|
The combination of inclusions and aliases is very powerful, because it
|
|
allows for parameterized property files. For example, the XML file for
|
|
the NAVCOM radio can include a parameter subtree at the start, like
|
|
this:
|
|
|
|
<PropertyList>
|
|
<params>
|
|
<comm-freq-prop>/radios/comm1/frequencies/selected</comm-freq-prop>
|
|
<nav-freq-prop>/radios/nav1/frequencies/selected</comm-freq-prop>
|
|
</params>
|
|
|
|
...
|
|
|
|
<chunk>
|
|
<type>number-value</type>
|
|
<property alias="/params/nav-freq-prop"/>
|
|
</chunk>
|
|
|
|
...
|
|
</PropertyList>
|
|
|
|
Now, the same instrument file can be used for navcomm1 and navcomm2,
|
|
for example, simply by overriding the parameters at inclusion:
|
|
|
|
<instrument include="../Instruments/navcomm.xml">
|
|
<params>
|
|
<comm-freq-prop>/radios/comm1/frequencies/selected</comm-freq-prop>
|
|
<nav-freq-prop>/radios/nav1/frequencies/selected</comm-freq-prop>
|
|
</params>
|
|
</instrument>
|
|
|
|
<instrument include="../Instruments/navcomm.xml">
|
|
<params>
|
|
<comm-freq-prop>/radios/comm2/frequencies/selected</comm-freq-prop>
|
|
<nav-freq-prop>/radios/nav2/frequencies/selected</comm-freq-prop>
|
|
</params>
|
|
</instrument>
|
|
|
|
Instrument Architecture:
|
|
-----------------------
|
|
Instruments are defined in separate configuration files. An instrument
|
|
consists of a base width and height, one or more stacked layers, and
|
|
zero or more actions. Base dimensions are specified as follows:
|
|
|
|
<PropertyList> <!-- remember, all xml files start like this -->
|
|
<name>Airspeed Indicator</name> <!-- names are good -->
|
|
<w-base>128</w-base> <!-- required width spec-->
|
|
<h-base>128</h-base> <!-- required height spec-->
|
|
<layers> <!-- begins layers section -->
|
|
|
|
Height and width can be overriden in the top level panel.xml by
|
|
specifying <w> and <h>. Transformations are caculated against the base
|
|
size regardless of the display size. This ensures that instruments
|
|
remain calibrated
|
|
|
|
Textures:
|
|
--------
|
|
FG uses red/green/blue/alpha .rgba files for textures. Dimensions for
|
|
texture files should be power of 2 with a maximum 8:1 aspect ratio.
|
|
The lowest common denominator for maximum texture size is 256 pixels.
|
|
This is due to the limitations of certain video accelerators, most
|
|
notably those with 3Dfx chipset such as the Voodoo2.
|
|
|
|
Instrument Layers**:
|
|
-------------------
|
|
The simplest layer is a <texture>. These can be combined in <switch> layers
|
|
|
|
<texture>
|
|
A texture layer looks like this:
|
|
|
|
<layer> <!-- creates a layer -->
|
|
<name>face</name>
|
|
<texture> <!-- defines it as a texture layer -->
|
|
<path>Aircraft/c172/Instruments/Textures/faces-2.rgb</path>
|
|
<x1>0</x1> <!-- lower boundary for texture cropping-->
|
|
<y1>0.51</y1> <!-- left boundary for texture cropping-->
|
|
<x2>0.49</x2> <!-- upper boundary for texture cropping-->
|
|
<y2>1.0</y2> <!-- right boundary for texture cropping-->
|
|
</texture> <!-- closing texure tag -->
|
|
</layer> <!-- closing layer tag -->
|
|
|
|
The texture cropping specification is represented as a decimal. There
|
|
is a table at the end of this document for converting from pixel
|
|
coordinates to percentages.
|
|
|
|
This particular layer, being a gauge face has no transformations
|
|
applied to it. Layers with that aren't static *must* include <w> and
|
|
<h> parameters to be visible.
|
|
|
|
<type> May be either text or switch..
|
|
|
|
<type>switch</type>
|
|
A switch layer is composed of two or more nested layers and will
|
|
display one of the nested layers based on a boolean property. For a
|
|
simple example of a switch see
|
|
$FG_ROOT/Aircraft/c172/Instruments/brake.xml.
|
|
|
|
<layer>
|
|
<name>Brake light</name>
|
|
<type>switch</type> <!-- define layer as a switch -->
|
|
<property>/controls/brakes</property> <!-- tie it to a property -->
|
|
<layer1> <!-- layer for true state -->
|
|
<name>on</name> <!-- label to make life easy -->
|
|
<texture> <!-- layer1 of switch is a texture layer -->
|
|
<path>Aircraft/c172/Instruments/Textures/brake.rgb</path>
|
|
<x1>0.25</x1>
|
|
<y1>0.0</y1>
|
|
<x2>0.5</x2>
|
|
<y2>0.095</y2>
|
|
</texture>
|
|
<w>64</w> <!-- required width - layer isn't static -->
|
|
<h>24</h> <!-- required height - layer isn't static -->
|
|
</layer1> <!-- close layer1 of switch -->
|
|
<layer2> <!-- layer for false state -->
|
|
<name>off</name>
|
|
<texture>
|
|
<path>Aircraft/c172/Instruments/Textures/brake.rgb</path>
|
|
<x1>0.0</x1>
|
|
<y1>0.0</y1>
|
|
<x2>0.25</x2>
|
|
<y2>0.095</y2>
|
|
</texture>
|
|
<w>64</w>
|
|
<h>24</h>
|
|
</layer2>
|
|
</layer>
|
|
|
|
Switches can have more than 2 states. This requires nesting one switch
|
|
inside another. One could make, for example, a 3 color LED by nesting
|
|
switch layers.
|
|
|
|
<type>text</type>
|
|
A text layer may be static, as in a label, generated from a property
|
|
or a combination of both. This example is a switch that contains both
|
|
static and dynamic text:
|
|
|
|
<layer1> <!-- switch layer -->
|
|
<name>display</name>
|
|
<type>text</type> <!-- type == text -->
|
|
<point-size>12</point-size> <!-- font size -->
|
|
<color> <!-- specify rgb values to color text -->
|
|
<red>1.0</red>
|
|
<green>0.5</green>
|
|
<blue>0.0</blue>
|
|
</color> <!-- close color section -->
|
|
<chunks> <!-- sections of text are referred to as chunks -->
|
|
<chunk> <!-- first chunk of text -->
|
|
<type>number-value</type> <!-- value defines it as dynamic -->
|
|
<property>/radios/nav1/dme/distance</property> <!-- ties it to a property -->
|
|
<scale>0.00053995680</scale> <!-- convert between statute and nautical miles? -->
|
|
<format>%5.1f</format> <!-- define format -->
|
|
</chunk>
|
|
</chunks>
|
|
</layer1>
|
|
<layer2> <!-- switch layer -->
|
|
<name>display</name>
|
|
<type>text</type> <!-- type == text -->
|
|
<point-size>10</point-size> <!-- font size -->
|
|
<color> <!-- specify rgb values to color text -->
|
|
<red>1.0</red>
|
|
<green>0.5</green>
|
|
<blue>0.0</blue>
|
|
</color> <!-- close color section -->
|
|
<chunks> <!-- sections of text are referred to as chunks -->
|
|
<chunk> <!-- first chunk of text -->
|
|
<type>literal</type> <!-- static text -->
|
|
<text>---.--</text> <!-- fixed value -->
|
|
</chunk>
|
|
</chunks>
|
|
</layer2>
|
|
|
|
|
|
Transformations:
|
|
---------------
|
|
A transformation is a rotation, an x-shift, or a
|
|
y-shift. Transformations can be static or they can be based on
|
|
properties. Static rotations are useful for flipping textures
|
|
horizontally or vertically. Transformations based on properties are
|
|
useful for driving instrument needles. I.E. rotate the number of
|
|
degrees equal to the airspeed. X and y shifts are relative to the
|
|
center of the instrument. Each specified transformation type takes an
|
|
<offset>. Offsets are relative to the center of the instrument. A
|
|
shift without an offset has no effect. For example, let's say we have
|
|
a texure that is a circle. If we use this texture in two layers, one
|
|
defined as having a size of 128x128 and the second layer is defined as
|
|
64x64 and neither is supplied a shift and offset the net result
|
|
appears as 2 concentric circles.
|
|
|
|
|
|
About Transformations and Needle Placement:
|
|
------------------------------------------
|
|
|
|
When describing placement of instrument needles, a transformation
|
|
offset must be applied to shift the needles fulcrum or else the needle
|
|
will rotate around it's middle. The offset will be of <type> x-shift
|
|
or y-shift depending on the orientation of the needle section in the
|
|
cropped texture.
|
|
|
|
This example comes from the altimeter.xml
|
|
|
|
<layer>
|
|
<name>long needle (hundreds)</name> <!-- the altimeter has more than one needle -->
|
|
<texture>
|
|
<path>Aircraft/c172/Instruments/Textures/misc-1.rgb</path>
|
|
<x1>0.8</x1>
|
|
<y1>0.78125</y1>
|
|
<x2>0.8375</x2>
|
|
<y2>1.0</y2>
|
|
</texture>
|
|
<w>8</w>
|
|
<h>56</h>
|
|
<transformations> <!-- begin defining transformations -->
|
|
<transformation> <!-- start definition of transformation that drives the needle -->
|
|
<type>rotation</type>
|
|
<property>/steam/altitude</property> <!-- bind it to a property -->
|
|
<max>100000.0</max> <!-- upper limit of instrument -->
|
|
<scale>0.36</scale> <!-- once around == 1000 ft -->
|
|
</transformation> <!-- close this transformation -->
|
|
<transformation> <!-- this one shifts the fulcrum of the needle -->
|
|
<type>y-shift</type> <!-- y-shift relative to needle -->
|
|
<offset>24.0</offset> <!-- amount of shift -->
|
|
</transformation>
|
|
</transformations>
|
|
</layer>
|
|
|
|
This needles has its origin in the center of the instrument. If the
|
|
needles fulcrum was towards the edge of the instrument, the
|
|
transformations to place the pivot point must precede those which
|
|
drive the needle,
|
|
|
|
Interpolation
|
|
-------------
|
|
Non linear transformations are now possible via the use of
|
|
interpolation tables.
|
|
|
|
<transformation>
|
|
...
|
|
<interpolation>
|
|
<entry>
|
|
<ind>0.0</ind> <!-- raw value -->
|
|
<dep>0.0</dep> <!-- displayed value -->
|
|
</entry>
|
|
<entry>
|
|
<ind>10.0</ind>
|
|
<dep>100.0</dep>
|
|
</entry>
|
|
<entry>
|
|
<ind>20.0</ind>
|
|
<dep>-5.0</dep>
|
|
</entry>
|
|
<entry>
|
|
<ind>30.0</ind>
|
|
<dep>1000.0</dep>
|
|
</entry>
|
|
</interpolation>
|
|
</transformation>
|
|
|
|
Of course, interpolation tables are useful for non-linear stuff, as in
|
|
the above example, but I kind-of like the idea of using them for
|
|
pretty much everything, including non-trivial linear movement -- many
|
|
instrument markings aren't evenly spaced, and the interpolation tables
|
|
are much nicer than the older min/max/scale/offset stuff and should
|
|
allow for a more realistic panel without adding a full equation parser
|
|
to the property manager.
|
|
|
|
If you want to try this out, look at the airspeed.xml file in the base
|
|
package, and uncomment the interpolation table in it for a very funky,
|
|
non-linear and totally unreliable airspeed indicator.
|
|
|
|
|
|
Actions:
|
|
-------
|
|
An action is a hotspot on an instrument where something will happen
|
|
when the user clicks the left or center mouse button. Actions are
|
|
always tied to properties: they can toggle a boolean property, adjust
|
|
the value of a numeric property, or swap the values of two properties.
|
|
The x/y placement for actions specifies the origin of the lower left
|
|
corner. In the following example the first action sets up a hotspot
|
|
32 pixels wide and 16 pixels high. It lower left corner is placed 96
|
|
pixels (relative to the defined base size of the instrument) to the
|
|
right of the center of the instrument. It is also 32 pixels below the
|
|
centerline of the instrument. The actual knob texture over which the
|
|
action is superimposed is 32x32. Omitted here is a second action,
|
|
bound to the same property, with a positive increment value. This
|
|
second action is placed to cover the other half of the knob. The
|
|
result is that clicking on the left half of the knob texture decreases
|
|
the value and clicking the right half increases the value. Also
|
|
omitted here is a second pair of actions with the same coordinates but
|
|
a larger increment value. This second pair is bound to a different
|
|
mouse button. The net result is that we have both fine and coarse
|
|
adjustments in the same hotspot, each bound to a different mouse
|
|
button.
|
|
|
|
These examples come from the radio stack:
|
|
<actions> <!-- open the actions section -->
|
|
<action> <!- first action -->
|
|
<name>small nav frequency decrease</name>
|
|
<type>adjust</type>
|
|
<button>0</button> <!-- bind it to a mouse button -->
|
|
<x>96</x> <!-- placement relative to instrument center -->
|
|
<y>-32</y>
|
|
<w>16</w> <!-- size of hotspot -->
|
|
<h>32</h>
|
|
<property>/radios/nav1/frequencies/standby</property> <!-- bind to a property -->
|
|
<increment>-0.05</increment> <!-- amount of adjustment per mouse click -->
|
|
<min>108.0</min> <!-- lower range -->
|
|
<max>117.95</max> <!-- upper range -->
|
|
<wrap>1</wrap> <!-- boolean value -- value wraps around when it hits bounds -->
|
|
</action>
|
|
<action>
|
|
<name>swap nav frequencies</name>
|
|
<type>swap</type> <!-- define type of action -->
|
|
<button>0</button>
|
|
<x>48</x>
|
|
<y>-32</y>
|
|
<w>32</w>
|
|
<h>32</h>
|
|
<property1>/radios/nav1/frequencies/selected</property1> <!-- properties to toggle between -->
|
|
<property2>/radios/nav1/frequencies/standby</property2>
|
|
</action>
|
|
<action>
|
|
<name>ident volume on/off</name>
|
|
<type>adjust</type>
|
|
<button>1</button>
|
|
<x>40</x>
|
|
<y>-24</y>
|
|
<w>16</w>
|
|
<h>16</h>
|
|
<property>/radios/nav1/ident</property> <!-- this property is for Morse code identification of nav beacons -->
|
|
<increment>1.0</increment> <!-- the increment equals the max value so this toggles on/off -->
|
|
<min>0</min>
|
|
<max>1</max>
|
|
<wrap>1</wrap> <!-- a shortcut to avoid having separate actions for on/off -->
|
|
</action>
|
|
</actions>
|
|
|
|
More About Textures:
|
|
-------------------
|
|
As previously stated, the usual size instrument texture files in FGFS
|
|
are 256x256 pixels, red/green/blue/alpha format. However the mechanism
|
|
for specifying texture cropping coordinates is decimal in nature. When
|
|
calling a section of a texture file the 0,0 lower left convention is
|
|
used. There is a pair of x/y coordinates defining which section of
|
|
the texture to use.
|
|
|
|
The following table can be used to calculate texture cropping
|
|
specifications.
|
|
|
|
# of divisions | width in pixels | decimal specification
|
|
per axis
|
|
1 = 256 pixels 1
|
|
2 = 128 pixels, 0.5
|
|
4 = 64 pixels, 0.25
|
|
8 = 32 pixels, 0.125
|
|
16 = 16 pixels, 0.0625
|
|
32 = 8 pixels, 0.03125
|
|
64 = 4 pixels, 0.015625
|
|
128 = 2 pixels, 0.0078125
|
|
|
|
A common procedure for generating gauge faces is to use a vector
|
|
graphics package such as xfig, exporting the result as a postscript
|
|
file. 3D modeling tools may also be used and I prefer them for pretty
|
|
items such as levers, switches, bezels and so forth. Ideally, the
|
|
size of the item in the final render should be of proportions that fit
|
|
into the recommended pixel widths. The resulting files can be
|
|
imported into a graphics manipulation package such as GIMP, et al for
|
|
final processing.
|
|
|
|
How do I get my panels/instruments into the base package?
|
|
-------------------------------------------------------
|
|
Cash bribes always help ;) Seriously though, there are two main
|
|
considerations. Firstly, original artwork is a major plus since you
|
|
as the creator can dictate the terms of distribution.All Artwork must
|
|
have a license compatible with the GPL. Artwork of unverifiable
|
|
origin is not acceptable. Secondly, texture sizes must meet the
|
|
lowest common denominator of 256e2 pixels. Artwork from third parties
|
|
may be acceptable if it meets these criteria.
|
|
|
|
* If there are *any* XML parsing errors, the panel will fail to load,
|
|
so it's worth downloading a parser like Expat (http://www.jclark.com/xml/)
|
|
for checking your XML. FlightGear will print the location of errors, but
|
|
the messages are a little cryptic right now.
|
|
|
|
** NOTE: There is one built-in layer -- for the mag compass ribbon --
|
|
and all other layers are defined in the XML files. In the future,
|
|
there may also be built-in layers for special things like a
|
|
weather-radar display or a GPS (though the GPS could be handled with
|
|
text properties).
|
|
|