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 supports Unity 5.6 and newer versions.


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.


  • Loading HDA files (*.hda,*.otl,*.otllc,*.hdalc,*.otlnc,*.hdanc).
  • Most of the SOPs that generate polygonal geometry.
  • All Parameter types including ramps (see Parameters)
  • Houdini Materials (similar to Version 1).
  • Curve SOP and curve editing (see Curves).
  • Input nodes and asset connections (Unity mesh, HDA) (see Inputs).
  • Object instancing (see Object Instancers).
  • Packed primitives (see 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 and Editing (for editable nodes) (see Painting and Editing Attributes).
  • Heightfield with height layer will be converted to Unity Terrain (see Terrain).
  • Transformer handles (xform) (see Handles).
  • LOD Groups (see Level of Detail).

Pending Implementation:

  • Heightfield with layers other than height to be converted to texture / mask.
  • Pinning.
  • Other input types (Curve, Terrain).


The following will not be supported in Version 2:

  • Animation Baking.
  • Option to Split geos by group (only collision and LOD groups are supported in v2).
  • Splitting points by vertex attributes (vertices are split by default in v2, but optionally can use points).
  • 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 will not work via Unity's built-in mechanism. Instead use the Duplicate Asset button on the HDA itself.
  • Deleting a generated asset GameObject that has been saved in a Scene will not remove any generated texture files in Unity project.