Houdini Engine for Unreal
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Getting Started

Installation

The Houdini Engine for Unreal plug-in is bundled together with the Houdini installer on Windows. Once the Houdini installer is started, simply select the Houdini Engine for Unreal component, to ensure that the plugin files are copied to the Houdini install folder.

More on installing

The installer extracts the Unreal plug-in for all supported Unreal versions. This includes the pre-built plug-in binary, source files and resource files. The extracted files can be found under the Houdini Install folder.

Note
Only the latest two versions of Unreal are actively supported. Source code of the plugin for older versions of Unreal can be downloaded in the HoudiniEngineForUnreal github repository.

<del>2. Copies the extracted plug-in folder into the Unreal install folder.<del>

Note
Version 1 of the plugin has been deprecated, only Version 2 is now available.

You then need to manually copy the HoudiniEngine folder of your choice, from the "engine/unreal" folder in your Houdini install directory, to the "Engine/Plugins/Runtime" directory of the Unreal Engine directory. Alternatively, the HoudiniEngine folder can also be copied to the "Plugins/Runtime" folder of your Unreal project.

Unreal will automatically load HoudiniEngine next time it is started. If another version of Unreal is installed later, it will not have the plug-in automatically. The plug-in can be installed by running the installer again.

Windows

Minimum Requirements:

  • Windows 7
  • Unreal 4.26
  • Houdini or Houdini Engine 19.0

Fastest way to get the plug-in working inside Unreal:

  1. Download and launch the houdini-X.Y.Z-win64-vc14.exe installer, where X.Y.Z is the version of Houdini.
  2. Follow the steps and make sure to select the Houdini Engine for Unreal option on the Houdini Engine installer screen.
  3. Copy the HoudiniEngine folder to the "Plugins/Runtime" of either your Unreal directory, or your Unreal project directory.
  4. Launch Unreal.

As on example, to install the V2 plugin to Unreal 4.27, you need to copy:

C:\Program Files\Side Effects Software\Houdini X.Y.Z\engine\unreal\4.27\HoudiniEngine

to:

C:\Program Files\Epic Games\UE4.27\Engine\Plugins\Runtime\HoudiniEngine

macOS

Note
Houdini18.5 does not ship with Version2 Binaries for MacOS for now. Currently, you will have to build the plugin from the source code available on the github repository.

Minimum Requirements:

  • macOS/OSX 10.14
  • Unreal 4.25
  • Houdini or Houdini Engine 19.0

Fastest way to get the plug-in working inside Unreal:

  1. Download and launch the houdini-X.Y.Z-macosx_*.dmg installer, where X.Y.Z is the version of Houdini.
  2. Follow the steps and make sure to select the Houdini Engine for Unreal option.
  3. Launch Unreal

During the install:

/Applications/Houdini/HoudiniX.Y.Z/Houdini Engine/unreal/4.25/Houdini Engine

is copied to:

/Users/Shared/Epic Games/UE_4.25/Engine/Plugins/Runtime/HoudiniEngine

Linux

As the Houdini Engine for Unreal is not officially supported on Linux, the plug-in's binaries are not available on Linux as part of the installer. The source code is, however, available either in the engine/unreal subdirectory of the Houdini install folder, or in the Github repository and can be compiled and used with the Linux version of Unreal.

To do so, simply follow the instructions under theInstalling from Source section on the Github repository to build the plug-in.

Note
Do not forget to call "source houdini_setup" from the Houdini installed folder that matches the plug-in (generally /opt/hfs19.0.XXX). This will prevent the Houdini Engine session from failing to be created.

Verify the plug-in is loaded

Once the Unreal plug-in has been installed, you can verify that it has been loaded in Unreal by opening the Project Settings window and navigating to the Plugins section. Houdini Engine will be listed amongst the plug-ins.

Alternatively, you can also easily check that the plugin is easily loaded by ensuring that Unreal has a "Houdini Engine" menu available in its main menu bar.

Unreal_HoudiniMenu.png

You can also check the version of Houdini the plugin was built against and is currently running against in the Plugin Information section. The "Built Against" and "Running Against" version numbers should match for the plug-in to work.

Unreal_ProjectSettingsHoudini.png

First Steps

The Houdini Engine plug-in provides the ability to import data generated by a Houdini Digital Asset (.hda) directly into Unreal via custom Unreal Assets which create Actors with custom Components: HoudiniAssetComponent.

These expose the Digital Asset's Parameters and Inputs and marshall the cooked Outputs as new Components.

More details are provided in the relevant sections.

Building the plugin from source

Source code for Version 2 of the plugin can be downloaded from the Github repository.

You will then need to build Unreal Engine from Source. To do so, you can simply follow this guide.

-# Within the UE4 source, navigate to the "Engine/Plugins/Runtime" folder, and copy the plugin source, or clone the plug-in's repository into a folder named HoudiniEngine.
-# Download and install the correct build of 64-bit Houdini. To get the build number, look at the header of Source/HoudiniEngine/HoudiniEngine.Build.cs, under Houdini Version.
-# Generate the UE4 Project Files (by running GenerateProjectFiles) and build Unreal, either in x64 Debug Editor or x64 Development Editor.
-# When starting the Unreal Engine editor, go to the Plug-ins menu and make sure the Houdini Engine v2 plug-in is enabled (in the Rendering section). Restart UE4 if you had to enable it.
-# To confirm that the plug-in has been successfully installed and enabled, you can check that the editor's main menu bar now has a new "Houdini Engine" menu, between "Edit" and "Window".
-# You should now be able to import Houdini Digital Assets (HDA) .otl or .hda files or drag and drop them into the Content Browser.
-# Once you have an HDA in the Content Browser you should be able to drag it into the Editor viewport. This will spawn a new Houdini Asset Actor. Geometry cooking will be done in a separate thread and geometry will be displayed once the cooking is complete. At this point you will be able to see asset parameters in the Details pane. Modifying any of the parameters will force the asset to recook and possibly update its geometry.