Home Digital assets 

Create a digital asset

Introduction

The overview of how to create a digital asset is to encapsulate functionality in a subnet, and then save the subnet as a new asset in an Operator Type Library (OTL) file.

You can create a digital asset for any Houdini network type. An asset will belong to the network type in which it was created (if you create an asset at the object level then it becomes an OBJ operator, if you create an asset at the geometry (SOP) level it becomes a SOP, and so on).

Naming a digital asset

All operator types (built-in types and digital assets) share a common namespace. If you ever have a situation where two different operator types have the same internal name (for example, two animators create character assets called my_character and they are eventually loaded into the same scene), using them can become very confusing.

It is a very good idea to create a naming convention for your digital assets to prevent “name collisions”. In large facilities a project’s technical director or systems administrator can decide the convention.

The convention might involve including one or more of the following pieces of information in the asset name:

  • Facility name

  • Project name

  • Author’s username

  • Version number

How to

  1. Encapsulate the network of nodes that provide the asset’s functionality inside a subnet.

    Anything being referenced by the operators inside your subnet must either be moved into the subnet or re-referenced through the asset’s interface.

    If you decide to put the linked nodes inside the subnet you will need to use network managers to mix network types. For example, if you put an object into a subnet that links to shaders under /shop, you must create a SHOP network manager inside your subnet and move your shader into the manager.

  2. Press RMB on the subnet node and choose Create Digital Asset.

  3. In the window that appears, give your new asset a unique internal name and a human-readable label. You can change the label later but the name cannot be changed after the asset is created.

  4. Use the sliders to set the minimum and maximum number of inputs to your new asset. In some cases, inputs may have been created when you collapsed your operators into a subnet.

    An asset with minimum inputs of 0 means the node doesn’t need to have an input connected to be valid. For object-level assets, this means the node doesn’t have to be parented.

  5. Use the Save to library field to choose an OTL file to save the new asset into.

    While it’s possible to save multiple assets into a single library file, we recommend you keep each asset in its own .otl file, and name it the same as the library. This makes managing assets in the pipeline much easier.

    By default $HOME/opCustom.otl is filled in. This is a good place to put assets when you are first learning. See managing assets for information on OTL locations.

    If you enter the special string Embedded instead of a filename, the asset will be saved in the .hip file instead of in a library.

  6. Use the Install Library To option to choose where you want the type library to be available:

  7. Click Accept. Houdini saves the new asset into the OTL file you chose.

  8. Houdini opens the type properties window to allow you to edit more properties of the new asset, including:

    See the options available in the type properties window .

Write help for an asset

You can write documentation for an asset to help explain the asset’s purpose and controls to the artists.

  1. Press RMB on an instance of the asset to open the asset’s operator type properties window.

  2. Click the Help tab.

  3. Write or paste wiki text or HTML into the text box.