A resource (also called an asset) is content from an external file that was created in an application other than the LevelEditor. Although resources can be of any file type, they are typically files that you use in a level, such as models made with the Autodesk® Maya animation software, behaviors written in a text editor, and textures created with Adobe® Photoshop® software. The LevelEditor provides built-in support for several resource file types.
When you drag and drop a resource from the Resources list to your LevelEditor document, the LevelEditor creates a reference to that resource. You can also drag-and-drop files from the Windows Explorer with the same result.
The Resources list displays Resources that are in a folder known as the Resource Root. The default Resource Root folder is the .\AssetRoot folder. To specify a different folder, select Edit > Preferences > Resources > ResourceRoot.
LevelEditor documents (.lvl files) use a relative path from the Resource Root folder to save the reference to the Resource. Thus, an .lvl file can always find a resource, regardless of where you save the .lvl file.
To add assets to the LevelEditor: