Houdini 20.0 Unreal

Coordinate Systems

On this page

Houdini and Unreal use two different coordinate systems.

Houdini (left) and Unreal (right) coordinate systems

Axis conversion

Houdini Engine for Unreal plugins converts all the transforms and geometries (positons, normals, etc.) from Houdini to Unreal’s coordinate system.

For example, an asset located at (0, 10, 05) in Houdini and (0, 05, 10) in Unreal retain the same location.

Vector3 Parameters

Vector3 paramters such as Integer or Float are identified and displayed using Unreal’s XYZ coordinates. However, other parameters do not.

This means a Y-position parameter in Houdini controls the Z-position in Unreal’s coordinates system.

To prevent Vector3 parameter from switching its Y and Z in Unreal, you need to set the parameter tags.

  • Set the Tag Name to hengine_noswap and the Tag Value to 1.

See Parameter tags for more information.

This results in Houdini and Unreal having the same XYZ and orientation values but different visual location and orientation.

Example: (left) default import settings from Houdini Engine. (right) add the Vector3 parameter to prevent the axis from switching.

Unreal

Getting started

Basics

Using Houdini Engine

Reference

Houdini Engine for Unreal Engine is a plug-in that allows integration of Houdini technology into Unreal. Session Sync and Node Sync are two features of the Houdini Engine Plugin to interact with a live session of Houdini.

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.

General information:

Compatibility:

Currently, the plugins has binaries that have been built for UE5.3, 5.2, 5.1, 5.0, UE4.27 and UE4.26, and is linked with the latest production build of Houdini.

Source code for the plugin is available on this repository for UE5.3, 5.2, 5.1, 5.0, UE4.27, UE4.26.

Note

UE5.1 and UE5.0 use the same source files/branches, the 5.0 sources are also intended to be used with 5.1.

Support and reporting bugs:

SessionSync

The Houdini Engine SessionSync feature allows you to connect to a session of Houdini Engine running inside Houdini with its GUI. It supports all the features of the regular Houdini Engine workflow and additional features specific to Session Sync.

Houdini Engine uses a non-UI version of Houdini while Session Sync lets you see and interact with the Houdini session through Houdini’s user interface. It also synchronizes changes made in either Unreal or Houdini so both programs can make changes and see the same results.

NodeSync

NodeSync is a feature for the Houdini Unreal Engine Plugin that enables sharing assets between Unreal and Houdini Session Sync. It works for Skeletal and static meshes.

You can send and receive data to and from Unreal without a dedicated HDA. It works with Static and Skeletal meshes as well as Actors.

Houdini Niagara

The Houdini-Niagara plugin allows you to exchange point cloud data between Houdini and Unreal’s Niagara system using the HoudiniNiagara Data Interface. You can export Houdini’s attribute data as HoudiniPointCache assets. These can then be imported into Unreal to use the Niagara systems and emitters to create complex effects and particle systems.

The Houdini KineFX Live Link plugin lets you control rigs in Unreal directly from KineFX in Houdini.