Digital asset definitions are saved in digital asset library files with a .hda extension. (Older versions of Houdini saved libraries with a .otl extension.) Houdini will load the assets from any library files it finds in HOUDINIPATH/otls and make them available to the user alongside the “factory” nodes included with Houdini.

The default library save location when you create a new asset is in your user account’s Houdini preferences directory (under HOUDINIPREFS/hda), so the asset will only be available to you. In a studio environment, you might save the asset in a central, network-accessible directory (that has been added to the Houdini path) so other users can install it.

• A large studio can put site-wide assets in a central, networked directory and make sure all artists have that directory in their $HOUDINI_PATH.

• You can put assets specific to a project in $JOB/hda. See project management for how to set up $JOB.

• You can put your own personal assets in the hda directory in your user account’s Houdini preferences. This is the default location when you create a new asset.

A library file can contain multiple assets (this means you can keep saving new assets into the library for your account). However, we generally recommend you store each asset in a separate library file. This makes it straightforward to share some assets and not others, and keep track of which assets are in which files.

• You can embed an asset in the current .hip file instead of in an external file. This may be useful for testing or sharing example files. When you create an asset, set the Save to library field to Embedded.

• You can enable an option to save the definitions of any assets used in a scene file with the scene file. This allows you to use the scene file even in environments where the asset libraries are not available, but can cause confusion about which definitions are being used. Choose Windows ▸ Operator type manager, click the Configuration tab, and turn on Save node definitions to HIP file.

• When an asset is both embedded in the scene file and available from a library file, by default Houdini will load the asset from the library. To reverse this, choose Windows ▸ Operator type manager, click the Configuration tab, and turn on Prefer definitions saved with HIP file.

• Although Houdini lets you embed an asset definition in the scene file, we recommend you store all assets in library files.

  One issue is that Houdini only embeds definitions for assets that are used in the scene. If you unknowingly delete the last instance of an asset and save, the definition of the asset will be lost.

Most places you can specify a file in Houdini will also accept a URL. You can use a web server to serve shared .hda asset libraries as well as shared project data (such as textures).