Houdini Engine for Unreal - Version 3

The source code in this branch is intended to be used with Unreal Engine 5.6 and 5.5, but should also be compatible with previous versions of UE5.

Welcome to the repository for the Houdini Engine For Unreal Plugin.

This plug-in brings Houdini's powerful and flexible procedural workflow into Unreal Engine through Houdini Digital Assets. Artists can interactively adjust asset parameters inside the editor and use Unreal assets as inputs. Houdini's procedural engine will then "cook" the asset and the results will be available in the editor without the need for baking.

Documentation for the plugin is available on the Side FX Website.

Feedback

Please send bug reports, feature requests and questions to Side FX's support.

Compatibility

Currently, the plugins has binaries that have been built for UE5.6, UE5.5, and is linked with the latest production build of Houdini.

Source code for the plugin is available on this repository for UE5.

Please note that all UE5.X versions of the plugin use the same source files/branches, the sources in the 5.0 branch are also intended to be used with more recent versions of the plugin (ie 5.6 , 5.5 etc.)

In general, we support the latest two releases of UE5.X, but will try to make the source code compatible with previous versions of Unreal.

For Houdini 21.0 - there is now two versions of the plugins: one with PCG support and one without PCG. Supporting PCG means that the Houdini Engine plugin now needs to depend on the PCG plugin, which is still considered experimental by Epic. We provide both versions of the plugin with your Houdini install and on this repo's release page, but the source code available here is with PCG support enabled. If you want to use the source code available here but would like to disable the PCG dependancy, instructions are provided at the bottom of this page.

Installing the plugin

1. In this GitHub repository, click Releases on the right side.

2. Download the Houdini Engine version zip file that matches your Houdini version.

3. Extract the HoudiniEngine folder to the Plugins\Runtime of your Unreal Directory. You can either copy it to Unreal's engine version directory or your Unreal project directory.

   In this example, Unreal's directory location is C:\Program Files\Epic Games\UE_5.4\Engine\Plugins\Runtime\HoudiniEngine and the project directory is C:\Unreal Projects\MyGameProject\Plugins\HoudiniEngine

   Note: For Unreal Engine 5, you must use Unreal's project directory.

Verify the Plug-in works

Once you install the Houdini Engine plug-in, you can verify it's loaded properly.

1. Open a new or existing Unreal project.
2. In the main menu bar, you can see Houdini Engine as a new selection.

You should also check the Houdini Engine plug-in version matches your Houdini Version for the plug-in to work properly.

1. In Unreal Engine main menu bar, click Edit then Plugins.
2. For Houdini Engine, check the HX.Y.Z. version number matches your Houdini version. X.Y.Z means your Houdini Version number.

You can learn how to export an Houdini Digital Assets (HDA), import it into Unreal Engine, and update the asset from Assets documentation.

Building from source

1. Get the UE source code from: https://github.com/EpicGames/UnrealEngine/releases
2. Within the UE source, navigate to Engine/Plugins/Runtime, and clone this repo into a folder named HoudiniEngine. Alternatively, you can also install the plugin in your project, in the Plugins/Runtime directory.
3. 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.
4. Generate the UE Project Files (by running GenerateProjectFiles) and build Unreal, either in x64 Debug Editor or x64 Development Editor.
5. When starting the Unreal Engine editor, go to Plug-ins menu and make sure to enable the HoudiniEngine v2 plug-in (in the Rendering section). Restart UE if you had to enable it.
6. To confirm that the plug-in has been successfully installed and enabled, you can check that the editor main menu bar now has a new "Houdini Engine" menu, between "Edit" and "Window".
7. You should now be able to import Houdini Digital Assets (HDA) .otl or .hda files or drag and drop them into the Content Browser.
8. 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.

Disabling PCG support when building from source

This guide is only for users who download the source code directly from the git repo, and want to disable PCG support. If you're getting the plugin source code from your Houdini install or the release page, we already provide versions of the source code with/without PCG support.

1. In the plugin's source folder, open the HoudiniEngine module's build.cs file: Source/HoudiniEngine/HoudiniEngine.Build.cs
2. Change private int HOUDINI_USE_PCG = 1; to private int HOUDINI_USE_PCG = 0;
3. Repeat the same change for the HoudiniEngineEditor and the HoudiniEngineRuntime modules'build.cs file. They're located respectively in Source/HoudiniEngineEditor/HoudiniEngineEditor.Build.cs and Source/HoudiniEngineRuntime/HoudiniEngineRuntime.Build.cs
4. Delete all the HoudiniPCGXXX.h/cpp files in the plugin's files.
5. Delete all the Intermediate and Binaries folder in the HoudiniEngine's plugin directory (if they exist).
6. Regenerate your project's file. On windows, this can be done by right-clicking on the uproject file, and selecting Generate Viual Studio Project Files
7. Build your project / the plugin.