Howto:Creating a simple modding framework
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This article is a stub. You can help the wiki by expanding it. |
Status
Objective
Background
Directory Structure
Mods should be using their own directory structure, resembling $FG_ROOT (the base package), e.g.:
- Aircraft
- GUI
- Textures
- Sounds
- Nasal
etc
Requirements
- register hooks to invoke callbacks for specific simulator/addon events
- mutual dependencies
Versioning
See FlightGear Version Check for the main article about this subject. |
Prototype
The protoype will be set up like this:
- an optional Nasal submodule stored in $FG_ROOT/Nasal/modding
- mods live under $FG_ROOT/Mods, each in its own folder
- each mod folder's structure will basically resemble the structure of the base package, with its sub-folders for resources like scripts, textures, sounds etc
- each mod will have a top-level
specs.mod
file - each
specs.mod
file is a conventional Nasal file that inherits from an interface class living in the Mod namespace - the
specs.mod
file implements routines for enabling/disabling and configuring the mod
Proof of Concept
The following snippet of code assumes that you put it into $FG_ROOT/Nasal/mod/mod.nas In addition, you need to add a folder to $FG_ROOT named Mods, beneath this folder you can add other folders - with each folder being treated as a separate "mod".
##
# $FG_ROOT/Nasal/mod/loader.nas
var ModdingRegistry = {};
var ModdingInterface = {
new: func() {},
del: func() {},
register: func(name) {
var slotNotEmpty = contains(ModdingRegistry, name);
if (slotNotEmpty) {
print("Warning: Overwriting/re-adding mod:", name);
ModdingRegistry[name].del(); # invoke the destructor of the mod
# ModdingRegistry[name] =
}
},
};
var fgroot = getprop("/sim/fg-root");
var modFolder = fgroot ~ '/'~ getprop('/sim/modding/mod-directory','Mods/');
# http://wiki.flightgear.org/Nasal_library#directory.28.29
var modDirectories = directory( modFolder );
# debug.dump( modDirectories );
foreach(var mod; modDirectories) {
print("Mod directory found:", mod);
}
## invoke:
# init code
# setup code
# loading code
# clean up code