Houdini Engine for Unity (v2 beta)
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About Version 2


This is a completely new version of the Houdini Engine for Unity plug-in, labelled as Version 2 (v2). It is currently in public beta and will be available alongside the older version (v1) of the plug-in. In the near future, once v2 is ready it will replace v1, and v1 will be deprecated.

This new version is written completely from the ground up for improved usability, updated feature set, and lightweight footprint in Unity projects.


Note that v2 is not compatible with v1 in the sense that:

  • It is not recommended to use both plug-in versions in the same Unity project.
  • HDAs that have already been instantiated and saved in a Unity project will need to be re-instantiated using the new plug-in. Currently there is no "upgrade" tool available to automate this.

Most HDAs used in the previous plug-in version should work similarly when re-instantiated in the Unity Editor, though some HDAs might require changes to the Unity-specific attributes.


Version 2 supports most of the features found in Version 1. More features will be supported throughout development over the next few months. The following lists will be updated to reflect that.

Currently Working

  • Loading HDA files (*.hda,*.otl,*.otllc,*.hdalc,*.otlnc,*.hdanc).
  • Most of the SOPs that generate polygonal geometry.
  • All Parameter types except Ramps.
  • Houdini Materials (similar to Version 1).
  • Curve SOP and curve editing.
  • Input nodes and asset connections (Unity mesh, HDA).
  • Object instancing.
  • Packed primitives.
  • Roundtrip support of material assignments and mesh names for input meshes.
  • Collision geometry generation via attribute (box, sphere, mesh).
  • Supports more than 65K triangles per mesh on Unity 2017.3+.
  • Houdini Engine Debugger sessions.
  • Bake as new standalone GameObject, and/or new prefab.
  • Bake Update existing standalone GameObject, and/or existing prefab.
  • Load, cook, and bake callbacks.
  • Connecting existing Unity materials and Substance materials via material attribute.
  • Connecting existing Unity script via attribute.
  • Play mode changes will be reverted after returning to Editor mode.
  • Undo in Unity will revert parameter changes and recook automatically.
  • Attribute Painting (for editable nodes).

Pending Implementation:

  • Ramp parameters.
  • Attribute Editing (for editable nodes).
  • Heightfield with height layer will be converted to Unity Terrain.
  • Pinning.
  • Other input types (Curve, Terrain).
  • Custom Handles.


The following will not be supported in Version 2:

  • Animation Baking.
  • Split geos by group.
  • Splitting points by vertex attributes.
  • Play mode per-frame cooking.


The following are currently known limitations with v2:

  • In Unity, after creating / loading an asset, immediately invoking Undo will not remove it from the scene.
  • Duplicating / Copy & Pasting an instantiated asset (i.e. GameObject with HEU_HoudiniAssetRoot component) will not work.
  • Unity 2017's new Experimental .NET 4.6 (issue with String parameters). The Stable .NET will work in 2017.x.
  • Deleting a generated asset GameObject that has been saved in a Scene will not remove any generated texture files in Unity project.
  • If using Houdini Engine Debugger session, crash might occur in Unity if session in Houdini is not closed before closing session in Unity. This is a bug in HAPI.