Tuesday, August 25th, 2020 Posted by Jim Thacker

Use Blender’s Cycles renderer inside Houdini with hdCycles

Tangent Animation’s open-source hdCycles plugin lets VFX artists use Blender’s Cycles render engine as a viewport renderer within Houdini. Video posted by Tangent Animation technical director Ben Skinner.

Animation firm Tangent Animation has released hdCycles, its open-source Cycles Hydra render delegate.

The plugin, which we reported on last month, enables Blender’s Cycles renderer to run as a viewport render engine within Houdini – and in the future, potentially any application that supports Hydra delegates.

Tangent’s ultimate goal is to render one-to-one representations of scenes in USD format, making it easier to use Blender in high-end animation and VFX pipelines.

Working towards a unified Blender-Houdini production pipeline
Tangent Animation is one of the highest-profile studios using Blender in production, having used the open-source 3D software on projects like Annie Award-nominated Netflix animated feature Next Gen.

Its work on hdCycles should help other studios that use both Blender and Houdini in their pipelines, making it possible to use Cycles as a viewport renderer within Solaris, Houdini’s look dev toolset.

With it, users should be able to create 3D assets in Blender, assemble them into a scene within Houdini, then export that scene back to Blender for rendering, with the assets displaying consistently throughout.

Supports the core elemts of a USD scene, including meshes, materials, lights and cameras
hdCycles makes Cycles a render delegate within Hydra, the imaging framework in USD (Universal Scene Description), Pixar’s open-source scene-exchange format, on which Solaris is based.

According to Tangent, its goal “render a one-to-one representation of a USD scene with Cycles”.

At the minute, it’s part of the way there: the current implementation supports basic meshes, materials, lights, points and curves, cameras and render settings.

Key features currently missing include volumes, advanced motion blur, full support for AOVs, tiled rendering and the Cryptomatte ID matte generation system.

On its GitHub repository, Tangent describes adding the missing features as its main priority, with stability and performance to follow, so use it in your own projectw with caution.

May make Cycles available as a viewport renderer in other DCC software
Nevertheless, the work goes a long way towards removing a barrier to adopting Blender within high-end VFX and animation pipelines, in which USD is becoming a critical technology.

The source code is also available to developers of other software that support Hydra render delegates, including Katana and Maya – currently via add-ons like Multiverse | USD, though direct support is planned.

Otoy has also announced that it will support Hydra delegates in its OctaneRender integration plugins, which could make it possible to use Cycles as a viewport renderer within apps like 3ds Max or Modo.

Availability and system requirements
hdCycles is available under an Apache 2.0 licence. The current 0.7 release is still officially listed as unstable, and in active developent.

Compiled binaries are available for Houdini 18.0.532+ on Windows only, although Tangent Animation’s GitHub repo has instructions on compiling the plugin from source on Windows and Linux.

Read more about hdCycles on Tangent Animation’s GitHub repository

Download the hdCycles plugin for Houdini