Houdini Engine Tools

Table of Contents

• Houdini Tools
• Custom Houdini Tool
• Default Houdini Tools

Added to the plug-in in Houdini 16.5, Houdini Tools are user-friendly shortcuts to hda files that reside in the Place Mode Tab.

They allow to easily apply Houdini Assets to the current selection in the World Outliner or the Content Browser. They can automatically assign inputs or be batch applied, and can have their functionalities and parameters described thanks to their tooltip help.

The plug-in comes with four Default Houdini Tools, but you can easily add your own Custom Houdini Tool by Drag and dropping HDAs on the Houdini Engine placement mode or by editing the Custom Houdini Tools Settings in the Houdini Engine tab of the project settings.

Houdini Tools

The Houdini Tools are available in the Houdini Engine section of the Place panel of the Modes Tab.

Double clicking on a tool will automatically instance and apply it to the current selection according to its Type. Houdini Tools can have the following types:

• Generator: Tools that simply generate geometry and do not need input to be automatically assigned when used. Generator tool will only use the current world selection to set their transform to the mean of all the transforms of the selected Actors.
• Operator (single): Tools that only need to have their first input automatically assigned when used. All objects selected will be assigned to that Houdini Assets's first input.
• Operator (multiple): Tools that need to have multiple inputs automatically assigned to be used. Each object selected will be assigned to its own input. The order in which the objects are selected will determine the order they will have in the assets inputs.
• Batch Operator: Tools that needs to be applied multiple times, once for each selected object. An instance of the tool will be created for each selected object, and the tool's first input will be set to that object.

As unselecting assets in the content browser can be done more easily than in the World Outliner, Content browser selection will always be used before selection in the World Outliner.

Content browser selection will automatically be assigned to Geometry Inputs.

World selection will automatically be assigned to World Outliner Inputs.

If only Landscapes are selected in the world, then inputs will be set to a Landscape Inputs.

Inputs that have been pre-assigned to Curve Inputs , will be not be changed / assigned.

Pressing Enter will allow you to edit the properties of the active tool, and pressing Delete will remove it.

Custom Houdini Tool

You can add your own HDA to the Houdini Tools. This can be easily done by drag and dropping one or more Houdini Asset from the Content Browser on the Houdini Engine placement mode. This will open a new Property Window that will allow you to edit your Tools Properties.

Adding a new Custom Houdini Tools will allow you to set the following values:

• Name : Name for the tool to be displayed in the Place panel.
• Type : Type of the tool, describing how the tools should handle selection and input assignment.
• Selection Type : Whether or not the tool should care about World selection, Content browser selection or both.
• Tooltip : The tooltip that will be displayed when hoovering the mouse cursor on the tool in the Place panel.
• Icon Path : Path to an Icon that will be used for your tool.
• Houdini Asset : The HDA file that will be created by the tool.
• Help Url : Url to your tool's help.

Custom tools can be edited or removed from the list by right clicking on them, or by pressing the Enter or Delete keys.

Alternatively, you can also edit them via the Custom Houdini Tools section in the Houdini Engine tab of the Project settings.

Default Houdini Tools

By default, the Houdini Engine plugin for Unreal comes with the following Houdini Tools:

• Rock Generator : Generator tool that creates procedural rock meshes.
• Boolean : Operator (multiple) tool used to apply boolean operation to two input objects.
• Polyreducer : Batch tool used to reduce the number of polygons of the input objects.
• Curve instancer : Operator (single) tool that scatters and instances the input object along a curve or in a zone defined by a closed curve.