File System

When the first specified -data_path is absolute, the current working directory may differ from the directory with the binary executable. However, when the path to the data directory is relative, the engine switches the current directory to the one with the binary executable.

When accessing a file outside the data directory (which is also not specified in an additional -data_path) via API, the path to such file should be specified relative to the current directory. For example:

// cbox.mesh is stored outside the data directory, so the path is specified relative to the current directory
ObjectMeshStatic cbox = new ObjectMeshStatic("../../data/cbox.mesh");

To extend the file system outside the main data directory, 3 ways are possible:

• Load external ZIP and UNG packages
• Add directories via ULINK
• Access external resources by using the additional -data_path command-line options

For the last variant, use the additional -data_path command-line options as follows:

-data_path "../" -data_path "D:/resources/my_project/test_0/" -data_path "../../resources/my_project/test_1/"

Paths can be both relative to the binary executable or absolute.

The list of all data paths specified on the application start-up can be obtained via API by using the following methods:

• getNumDataPaths()
• getDataPath(int num)

The getDataPath() function without arguments will return the first specified-data_path directory.

ULINK

Partial paths simplify handling of files. If you want to load a file and you are sure that there is only one resource with a given name in the data folder, only a file name can be provided without a path. If a name is not unique, the first found file with such name is loaded. It is also possible to provide a sub-path that uniquely specifies a file. For example, to load data/project/image_1.tga, you can use image_1.tga (if a name is unique) or project/image_1.tga.

When relative paths are used, you can relocate your Unigine-based application or copy it onto another machine, and all resources will be properly loaded. There is no loading speed penalty as well: it is as fast as loading files by an absolute path due to name caching.

As file names are cached, usually the same name and path should be used to load and remove file when accessing from your source code by using FileSystem functions:

• For default resources, functions return full paths relative to the data folder.
• If you load a file and specify a relative path, use a relative path to delete the resource.
• If you load a file using an absolute path, use an absolute path to delete the resource.

By default, all of the file names inside archives are case sensitive. It is true even for Windows, where unpacked files are case independent. So, if you have errors on file opening, check the file name case first.

You can make the file system case insensitive by using the filesystem_icase console command.

Dynamic scanning allows the engine to cache names of all files within the data folder on the startup; this enables tracking file changes in real-time.

If the dynamic scanning is not necessary or takes too many resources, you can use the pre-cashed file hierarchy that is specified in the .ulist file. When the engine finds this file in a folder during the startup scanning, it stops and uses the list of files specified there.

The .ulist file is generated by using the special script externs/bin/datalist.py that should be run from the data folder.

The dynamic scanning of the file system allows automatic resource reloading. For example, if an artist changes a texture or a mesh file on the disk, it will automatically change in the world.

Unigine supports two types of file archives to save space or pack the production version of resources:

• UNG (a Unigine-native format for archives created with Archiver tool)
  Notice

  The maximum size for a file inside a UNG archive is limited to 2 GB.
• ZIP

UNG and ZIP archives are loaded automatically if they are found within the data folder. File names are cached just like in case with non-archived files.

Archives are completely transparent to the engine. There is no need to explicitly unpack the archives, as their content is automatically handled as not packed. Archived files are addressed as if they are non-archived. For example, if you have data/project/archive.ung and want to address directory/file.txt within it, simply specify the following path: project/directory/file.txt or even file.txt (only if the file name is unique).

Inside the archive, files can be organized in any way. However, in the root of the archive only files with unique names should be placed. Otherwise, the file search will return incorrect results.

Here is an example of an incorrect file tree for an archive:

• my_archive.ung
  • my_folder
    • file_2.txt
  • file_1.txt
  • file_2.txt

The correct archive structure can be specified as follows:

• my_archive.ung
  • my_folder
    • file_2.txt
  • another_folder
    • file_2.txt
  • file_1.txt

If there is a name collision between an archived file and a non-archived one, the first matching file is returned. The search is performed in the following order:

1. Unarchived files
2. Files in UNG archives
3. Files in ZIP archives

From Unigine API, archives are handled using FilesSystem functions as well.

It is possible to add UNG and ZIP archives to the cached file system even if they are stored outside the data folder. External packages are added only on the start-up. Use one of the following methods for that:

• Add archives on the start-up via -extern_package CLI option (together with the rest of required ones). Relative and absolute paths can be used.
  Shell commands

  bin\main_x86d.exe -extern_package "../../my_project/archive.ung"

  Several packages:
  Shell commands

  bin\main_x86d.exe -extern_package "../2/core.ung" -extern_package "D:/Unigine/core.ung"

• Using Unigine API, via loadPackage() function.

As well as the data paths, the paths to external packages won't be saved into the configuration file. However, they can be added to it manually.

For example, three localization languages are supported in the project: English (by default), German and French. Depending on the language, different splash textures need to be loaded on the start-up.

To organize your resources, name them using the following file modifiers:

• data
  • splashes
    • splash.png (this would be a default version of the texture. In our case, a texture with an English title)
    • splash.de.png (a German title)
    • splash.fr.png (a French title)

After that, in the code you need to specify what modifier to use via engine.filesystem.addModifier(). This function is called in the system script (unigine.cpp) since a modifier need to be registered before the world and its resources start to be loaded. For example, to load a German splash screen and the low resolution textures interface:

// unigine.cpp

int init() {
	...
	
	// Register modifier
	engine.filesystem.addModifier("de");
	
	// Set a splash texture
	engine.splash.setWorld("textures/splash.png");   // splash.de.png will be automatically used
	...
	
	return 1;
}

Also you can use -extern_define CLI option to pass the language (for example, if a user chooses a language in the launcher).

bin\main_x64d.exe -extern_define "LANG_DE"

And here is how passed defines can be handled in the code.

// unigine.cpp
string lang = "";

int init() {
	...
	
	// Parse EXTERN_DEFINE
	#ifdef LANG_DE
		lang = "de";
	#elif LANG_FR
		lang = "fr";
	#endif
	
	if(lang != "") {
		engine.filesystem.addModifier(lang);
	}
	
	// Set a splash texture: splash.de.png or splash.fr.png will be used if the language is passed
	engine.splash.setWorld("textures/splash.png");	// otherwise, splash.png
	...

	return 1;
}