Houdini 19.5 Nodes Render nodes

Net Barrier render node

Blocks the ROP network until synchronization occurs.

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Since 10.0

The Net Barrier uses the tracker to ensure multiple machines stay in step with each other. This is useful if some external shared drive is being used to transfer data and you need to make sure that the machines don’t out pace each other.



Begins the render with the last render control settings.


Opens the render control dialog to allow adjustments of the render parameters before rendering.

Render with Take

Uses the settings in a particular take while rendering. Choose Current to use the current take when rendering.

Valid frame range

Limits the rendering of frames, when set to Render frame range or Render frame range only.

Render any frame

Allow the renderer to render any and all frames.

Render frame range

Only render the frames in the range set below, but allow the renderer to render other frames if they are referenced by in-range frames.

Render frame range only (strict)

Only render the frames in the range set below, and don’t allow the renderer to render other frames, even if they are referenced by in-range frames.


The port specified when starting the simtracker.py process for communication.


What machine will run the simtracker.py process for synchronization. If this is blank, no attempt at synchronization or data transfer will occur.

Job Name

The job name to describe this synchronization or data exchange event. By using different job names one can have machines part of separate data-exchange and synchronization events.



Cooking is blocked until the given number of peers report into the tracker that they are done. Then they are all allowed to continue. Useful if you have a bunch of machines you need to operate in lock step.

Post Barrier Value

The given synchronization value is posted as the current barrier value for the job name. The machine is allowed to continue unimpeded. This is useful for a producer machine whose output other machines depend on, but which can operate as fast as it wishes.

Wait Barrier Value

Waits for the barrier value stored in the job name to reach the synchronization value. Then it is allowed to continue. This is useful to ensure consumer machines do not outpace the producers.


The slice number that this machine should report itself as. Each machine connecting under the job name should have its own unique slice number. Sometimes this can be inferred from the operation so this parameter will be absent.

Number of Peers

Total number of machines that have to synchronize. Sometimes this can be determined from the operation so this parameter will be absent.

Synchronization Value

The barrier value to post, if in post mode, or to wait for, if in wait mode.


A script command can be specified for execution at the various execution points. The expression language selected for the parameter determines whether this command are hscript or python statements.

Prior to execution, this node is automatically set as the global current node.

To run statements from a file instead, specify the path to the file with either a .cmd extension (when the language is set to Hscript), or .py extension (when the language is set to Python). Additional arguments to the script can also be supplied, they will be parsed in a shell-like manner.

Pre-Render Script

Run this script before any rendering.

Pre-Frame Script

Run this script before each frame.

Post-Frame Script

Run this script after each frame.

Post-Render Script

Run this script after all rendering.



Frame being rendered.


Total number of frames being rendered.


netbarrierpost Example for Net Barrier render node

In this example, we demonstrate how a netbarrier ROP node can be used to ensure that multiple machines stay in sync with each other.

Render nodes

  • Agent

    This output operator is used to write agent definition files.

  • Alembic

    Exports the scene to an Alembic archive. Alembic is a common exchange format for moving geometry and animation between different 3D software packages.

  • Archive Generator

    Generates disk-based archives which can be used by either mantra or RIB renderers.

  • Bake Animation

    Bakes animation from object transforms and CHOP overrides.

  • Bake Texture

    Generates a texture map from one or more objects' rendered appearance.

  • Batch

    Renders the input ROP in a single batch job.

  • Brick Map Generator

    Allows you to convert Houdini volume primitives into Pixar brickmap files.

  • Channel

    The Channel output operator generates clip files from a particular CHOP.

  • Composite

    The Composite output operator renders the image(s) produced in the Compositing Editor.

  • DSM Merge

    Merges two or more deep shadow/camera map files.

  • Dem Bones Skinning Converter

    Converts any non-changing topology deforming mesh sequence into a bone-based animation.

  • Dynamics

    Saves the state of a DOP network simulation into files.

  • Fetch

    Makes a dependency link to a ROP in a different network.

  • Filmbox FBX

    Exports entire scenes to FBX files.

  • Filmbox FBX Animation

    Export animation from geometry-based skeleton to an FBX file.

  • Filmbox FBX Character

    Export a skinned character with geometry-based skeleton to an FBX file.

  • Frame Container

    Prevents frame dependency changes in the contained nodes from affecting its inputs.

  • Frame Depedency

    Allows an output frame to depend on one or more input frames.

  • GLTF Character

  • Geometry

    Generates geometry files from a SOP or DOP network.

  • HQueue Render

    HQueue, or Houdini Queue, is a distributed job scheduling system.

  • HQueue Simulation

    HQueue, or Houdini Queue, is a distributed job scheduling system.

  • Hair Card Texture

    Renders hair textures for use on hair cards.

  • Karma

    Renders non-USD scenes using Houdini’s Karma renderer.

  • Labs 3D Facebook Image

    Quickly render a 3D scene to a 2.5D image that can be uploaded to Facebook.

  • Labs Flipbook Textures

    Renders, composites, and exports flipbook textures.

  • Labs JSON Exporter

    Export geometry attibutes to a JSON file.

  • Labs Marmoset Export

    The Marmoset Export ROP allows you to quickly generate an mview inside Houdini

  • Labs Niagara ROP

    Export point caches to be used with Unreal’s Niagara particle system.

  • Labs Sketchfab

    Uploads geometry to Sketchfab

  • Labs Vertex Animation Textures

    The Vertex Animation Textures ROP will export a mesh and a set of textures to be used with a shader for complex real-time effects, such as: soft-body deformation, rigid-body dynamics, dynamically remeshed geometries, and particle sprites.

  • MDD Point Cache

    This output operator is used to write an MDD animation file.

  • Mantra

    Renders the scene using Houdini’s standard mantra renderer and generates IFD files.

  • Mantra Archive

    Generates disk-based archives which can be used by mantra.

  • Merge

    Merges several render dependencies into one.

  • Net Barrier

    Blocks the ROP network until synchronization occurs.

  • Null

    Does nothing.

  • OpenGL

    Render an image using the hardware-accelerated 3D viewport renderer.

  • Pre Post

    Renders ROPs before and after a main job.

  • Render nodes

    Render nodes either render the scene or set up render dependency networks.

  • Shell

    Runs an external command.

  • Subnetwork

    The SubNetwork output operator provides an easy way to manage large number of output operators.

  • Switch

    Renders one of several inputs.

  • Tractor

    Tractor is a program shipped out with Pixar’s distribution of RenderMan.

  • USD

    Renders a LOP network out to one or more USD files. This node is available as render node or as a LOP.

  • USD Render

    Renders an output image from the stage generated by a LOP network.

  • USD Stitch

    Merges USD files representing individual frames by composing them.

  • USD Stitch Clips

    Merges multiple value clips representing individual frames.

  • USD Zip

    Assembles USDZ archive files from existing USD files.

  • Wedge

    Re-renders the same ROP multiple times with different settings

  • Wren

    This output operator is used to drive the Wren rendering program.

  • glTF