This article explains the directory and file layout which Stellarium uses from a programmer's perspective, lays out the rationale behind it, and uses examples to illustrate the way things work.
Files are broadly separated by the type of data. For StelModules which need many data files, there is one directory. e.g. StarMgr files are stored in the
stars directory, LandscapeMgr files may be found in the
There are also directories which are shared among modules and other parts of the program, for example the
When Stellarium searches for data, texture and other files it looks in two separate locations:
The User Data Directory, which stores per-user copies of any customised data files. It is the place where Stellarium saves the configuration file, recorded scripts and can also be used to override files in the Installation Data Directory if the user wishes to customise Stellarium. The location of this directory varies depending on the operating system.
|Linux / BSD / other POSIX|
|Windows 2000 / XP||This is the |
|Windows Vista||This is the |
The directory tree within the User Data Directory is the same as the Installation Data Directory. Any file which exists in the User Data Directory will over-ride that in the Installation Data Directory.
For example, to modify the position of a nebula texture, the user may copy the
nebulae/default/nebula_textures.fab file from the Installation Data Directory to the
nebulae/default sub-directory of the User Data Directory and modify it there. In this manner, each user on a multi-user system may have their own customized Stellarium data files.
The Installation Data Directory, which is where the program executable, libraries and all data files which are distributed with the program are installed. It is the place where Stellarium's data files are installed on your computer. This directory varies depending on the operating system.
|Linux / BSD / other POSIX||It depends on the installation prefix used when building Stellarium. If you built from source, and didn't explicitly specify an install prefix, the prefix will be |
|Windows||It depends on where Stellarium is installed. The main Stellarium installation directory is the Installation Data Directory. Typically this will be |
|MacOS X||The Installation Data Directory is found inside the application bundle.|
Important data files which may be found in the Installation Data Directory include:
data/ssystem.ini: the solar system bodies description file
stars/default/*: star catalogues
nebulae/default/*: nebula textures and data files
scripts/: script files
textures/: general purpose texture files (button icons etc)
landscapes/*/*: landscape textures and data files
If a file exists in the User Data Directory, it will be used in preference to a file with the same name existing in the Installation Data Directory. This allows users to customise data files, textures and so on without modifying the originally installed files.
There are several reasons for doing this:
Whenever a file is needed in Stellarium, it should be located using the StelFileMgr class. This class will find the file in the first location in the search path. An instance of this class is maintained by the StelApp singleton. StelFileMgr::findFile() will throw exceptions when a problem is encountered, so it is important to always use
try ... catch ... exception handling when using it.
For example. You are writing a class called Comet, and wish to search for a data file called
comets.dat located in the
data directory, you would go about it like this:
As you can see, the file is specified only by the partial path. This partial path is appended first to the User Data Directory. If, and only if the file is not found there, it is searched for in the Installation Data Directory. Thus if the user has a customised copy at:
<User Data Directory>/data/comets.dat it will be used, else the version in the Installation Data Directory will be used.
Stellarium ships with the first four star catalogue files of nine files. The implementation of a catalogue downloading tool helps ease the task for users wanting the extra catalogues by automating the download and installation procedure.
The files which come with Stellarium are found by the partial paths:
stars/default/stars_0_0v0_1.cat stars/default/stars_1_0v0_1.cat stars/default/stars_2_0v0_1.cat stars/default/stars_3_1v0_1.cat
Naturally, these files are to be located in the Installation Data Directory (because they ship with the installer).
The catalogue downloader tool runs within Stellarium. When it downloads extra star catalogue files, it should place them in the User Data Directory. After downloading all the catalogues, the paths to the various files should look like this:
<Installation Data Directory>/stars/default/stars_0_0v0_1.cat <Installation Data Directory>/stars/default/stars_1_0v0_1.cat <Installation Data Directory>/stars/default/stars_2_0v0_1.cat <Installation Data Directory>/stars/default/stars_3_1v0_1.cat <User Data Directory>/stars/default/stars_4_1v0_0.cat <User Data Directory>/stars/default/stars_5_2v0_0.cat <User Data Directory>/stars/default/stars_6_2v0_0.cat <User Data Directory>/stars/default/stars_7_2v0_0.cat <User Data Directory>/stars/default/stars_8_2v0_0.cat
It might be that someone makes a customised installer of Stellarium which includes all the star catalogues with the main installation - perhaps on a special edition DVD. In this case, all the files would be in the <Installation Data Directory>/stars/default directory. The downloader tool should be able to cope with this, not re-downloading files into the User Data Directory which already reside in the Installation Data Directory.