Table of Contents

Setup the Houdini Engine in Unity 3D.

Installing the Houdini Engine Plugin

The following outlines the process to install the Houdini Engine plugin into Unity 3D. The Houdini session in Unity 3D allows bi-directional communication between a running instance of Houdini Engine and the Unity 3D game engine editor.


  • Install SideFX Houdini Engine Plugin.
  • The unitypackage is located at ‘InstallLocation/engine/unity/HoudiniEngineUnity.unitypackage‘.
  • The HoudiniEngineUnity.unitypackage will install the Unity Package Plugin into the current project located in the Assets/Plugins directory.
  • In Unity’s Project Pane, Right click Import Package > Custom Package.
  • Navigate to and Select the HoudiniEngineUnity.unitypackage file.
  • Select OK


To verify that the Houdini Engine is running a valid session, navigate to the Houdini > Session > Session Info dialog to see the current session information.

unity houe sessioninfo

Session Info

The Session Info popup displays the current information about the Houdini Engine session started in Unity 3D.

unity houe sessioninfo popup

Installation Info

When installing the Houdini Engine in Unity for the first time inside a project, the session pipe(bi-directional communication) might not have been initialized correctly.

If the session pipe was not created, a popup will be displayed with the following message; “Unable to detect Houdini Engine installation

unity houe installationinfo notconnected

If you know that Houdini works on your system and have the application working, the next step is to try and release any existing sessions and restart another pipe session to connect to the Houdini Engine.

Start a Houdini Engine Session

If the pipe session did not start correctly,

  • Select the Houdini Engine > Session > Create > Pipe Session menu item.
  • You will now see in the console something like “Houdini Engine: Created Pipe session with ID 1486619600.

The running Houdini Engine Session

Great, now the session is piped and flowing, we now can verify our installed version of the Houdini Engine.

  • Select Houdini Engine > Installation Info menu item

You should now see the following popup; “Installed Houdini Engine Version: 3.2.40

unity houe installationinfo connected

Now that the Houdini Engine is installed and running, time for that black hole!

Create unity_houdini.env file

For the bi-directional asset flow to work, Houdini Engine and Unity need to have an agreed upon workspace. This env file declares environmental variables that are OS level that each application can share.

This effectively allows the Houdini and Unity project to merge on the filesystem level and work together streamlining the asset pipeline even more.

  • Create an Environment Variable in Houdini named HEU_ENVPATH_JOB.
  • HEU_ENVPATH_JOB = C:/Users/Mike/Documents/HoudiniProjects/Test_PDG_01
  • Update the Local Scheduler node – Scheduler > Working Directory with the $HEU_ENVPATH_JOB variable name.
  • Update HDA Processor nodes with $HEU_ENVPATH_JOB/hda directory location as setup when creating the Houdini .hip/.hiplc project. e.g. $HEU_ENVPATH_JOB/hda/tg_box_machine.hdalc

Houdini v17.5.173

See Also