Houdini 22.0 Nodes Render nodes

glTF 2.0 render node

Since 22.0

The glTF 2.0 ROP can export your scene as a GLTF file. See glTF format for further information.

Note

See the following link for an overview of importing and exporting glTF files to and from Houdini.

The follow table provides further details about which glTF features and extensions are supported, plus any relevant notes about how they are supported:

glTF Property or Extension

Supported

Notes

Scene

All nodes will be exported to a single scene, which can be optionally named with the Scene Name parameter.

Node

When exporting an Object network, a glTF node will be exported for each OBJ node.

When exporting a SOP, the behaviour will differ depending on how the node parameters are configured. By default, only a single glTF node will be exported, along with a mesh and as many mesh primitives as are needed. If the Build Hierarchy from Path Attribute parameter is enabled, a glTF node will be exported for every unique path in the geometry being exported.

Mesh

SOP geometry will be exported to a glTF mesh. Sometimes exported geometry needs to be processed to make it compatible with glTF, such as by triangulating the geometry or splitting points when vertices sharing that point have different attribute values.

Mesh Primitive (Points)

Point clouds will be exported to a mesh primitive with mode POINTS.

Note

This is not supported when Draco mesh compression is enabled.

Mesh Primitive (Lines)

Lines will be exported to a mesh primitive with mode LINES.

Note

This is not supported when Draco mesh compression is enabled.

Mesh Primitive (Triangles)

Triangular polygon meshes will be exported to a mesh primitive with mode TRIANGLES.

Camera

Both OBJ cameras and SOP primitive cameras are supported and will be exported unless Export Cameras is disabled.

Skin

-

Morph Target

-

Animation (Transform Target)

Animated OBJ node transforms will be exported to a single glTF animation or multiple glTF animations (if Export Animations to is set to Multiple Clips).

Animation (Weight Target)

-

Material

Supported materials assigned to geometry in the scene will be exported.

Texture

Supported texture maps used by supported materials in the scene will be exported, as well as any textures specified by the Additional Textures parameter.

KHR_draco_mesh_compression Extension

Meshes will be exported with Draco mesh compression when Use Draco Compression is enabled. Draco mesh compression only supports triangle primitives.

KHR_lights_punctual Extension

Any OBJ lights in the scene will be exported unless Export Lights is disabled.

Parameters

Save to Disk

Begins the render with the last render control settings.

Controls

Opens the Render Control window, which allows you to adjust the render parameters before rendering.

Valid Frame Range

Controls whether this render node outputs the current frame or the image sequence specified in the Start/End/Inc parameters.

Render Current Frame

Export only the current frame.

Render Frame Range

Export the frames in the Start/End/Inc frame range, but also allow exporting of frames referenced by in-range frames.

Render Frame Range Only (Strict)

Only export the frames in the Start/End/Inc frame range. Do not allow exporting of other frames, including frames referenced by in-range frames.

Start/End/Inc

Specifies the range of frames to render (start frame, end frame, and increment). All of the values can be floating point values. The range is inclusive.

The Start/End/Inc parameters determine the values of the below local variables for the output driver.

$NRENDER

The number of frames to be rendered by the output driver.

$N

The current frame being rendered (starting at 1 and going to $NRENDER).

For example, if the parameters are set to:

Start

End

Inc

10.5

12

0.5

… there will be 4 frames rendered (10.5, 11, 11.5, and 12), so $NRENDER will have a value of 4.

$N will have the following values at each frame:

Frame

$N

10.5

1

11

2

11.5

3

12

4

Render with Take

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

Output File

The path of the file written by the node. The extension determines the type of file that is written.

A path with a .glb extension generates a single binary GLB file and stores all resources (such as images) within the file.

A path with a .gltf extension may store some resources externally as separate files. Exported resource files are written to the same folder as .gltf and are referenced using relative paths.

Create Intermediate Directories

When turned on, automatically creates intermediate directories in the Output File path. When off, the path must exist or the node will raise an error.

glTF

Use SOP Path

When turned on, outputs a single SOP node to the outputted glTF file instead of an Object node graph.

SOP Path

When Use SOP Path is turned on, specify the path to the SOP node to export.

Build Hierarchy from Attribute

Use a primitive string attribute for creating nodes in the output file. Each string value is treated like a path to a node in the glTF scene. If the primitive is a packed primitive, then the exported node takes on the primitive’s transform.

Note

This parameter is only available when used from the Geometry context or when the Use SOP Path parameter is on.

Path Attribute

The name of the attribute containing the path used for Build Hierarchy from Path Attribute.

Root Object

When exporting an Object graph, specifies the root object of the scene. All displayed objects contained under this node will be included in the exported glTF file.

Objects

A pattern/bundle of objects to include in the exported glTF scene.

Scene Name

The name of the exported glTF scene property. When blank, the name property will be omitted.

Copyright

The text to include in the exported glTF asset’s copyright property.

Use Draco Compression

Turn on the Draco mesh compression extension for exported meshes.

Note

KHR_draco_mesh_compression currently only supports triangle primitives. You cannot export point clouds or curve primitives which are supported when Use Draco Compression is off.

Export Custom Attributes

When turned on, all attributes that are prefixed with _ (as defined in the glTF specification) are exported as custom attributes. When off, only attributes defined in the glTF standard are exported.

Attributes are exported with their original types whenever possible. However, glTF allows a maximum of 32 bits for floats and integers which means that a narrowing conversion can occur.

Note

glTF only supports point attributes, so any custom vertex, primitive, or detail attributes you want to support must be promoted to point attributes.

Export Extras

When turned on, exports dictionary attributes to glTF property fields. This can include any arbitrary user data in the exported glTF file.

Extras are currently supported for the following glTF property types:

  • Scene

  • Node

  • Mesh

  • Skin

Refer to the table below to see the expected attribute names and attribute classes that the node will search for when exporting extras:

Extras Property Owner

Dictionary Attribute Name

Supported Attribute Classes

Scene

gltf_scene_extras

Detail

Node

gltf_node_extras

Primitive, Detail

Mesh

gltf_mesh_extras

Primitive, Detail

Skin

gltf_skin_extras

Detail

Export Materials

When turned on, exports any materials associated with geometry that is being exported. The exporter looks for the standard shop_materialpath primitive attribute to determine the material of geometry being exported.

The list of supported materials that the exporter can translate to glTF are:

  • Principled Shader

  • Mtlx Gltf Material

Export Cameras

When turned on, also exports cameras. For an Object graph, it exports camera objects that match the Objects pattern or bundle. FOr a SOP node, it exports camera primitives found in the SOP geometry.

Export Lights

When on, also exports any light objects matching the Objects pattern/bundle. This will create a dependency in the exported glTF file on the KHR_lights_punctual extension.

Image Export

Controls where images are exported to when exporting material texture maps.

Embed in glTF File

The image will be saved as a binary blob either directly within a .glb file or within the associated .bin data file of a .gltf file.

Save to External File

The image will be saved on disk as its own file. Like all exported resources, it’s stored in the same folder as the output glTF file and referenced relatively by the same glTF file.

Image Format

Controls the format of an exported image. glTF supports JPEG and PNG images.

Original or PNG

Images will be exported in their original format if supported by the glTF standard and PNG otherwise.

Original or JPEG

Images will be exported in their original format if supported by the glTF standard and JPEG otherwise.

PNG

Images will be exported as a PNG.

JPEG

Images will be exported as a JPEG.

Additional Textures

This multi-parameter can specify additional textures that should be exported to the glTF file. This is useful to have images included in the exported glTF file that are not associated with any materials being exported from your Houdini scene.

Export Animations to

Controls how animations are interpreted and exported by the exporter.

Single Clip

Any animations in the Houdini scene exports to a single glTF animation.

Multiple Clips

Any animations in the Houdini scene exports to multiple clips defined by the user with a frame range that delineates each animation clip in the Houdini scene.

None

Any animations in the Houdini scene will be ignored and no animations will be exported to the glTF file.

Animation Name

When Export Animations to is set to Single Clip, this defines the name of the exported animation property.

Animation Clips

When Export Animations to is set to Multiple Clips, this multi-parameter sets the number of clips, the name of each clip, and the frame range that delineates the animation within the Houdini scene.

Scripts

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

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

To run statements from a file, specify the path to the file with either a .cmd extension (when the language is set to Hscript) or a .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-Write Script

Run this script after each frame’s data finishes writing to disk.

Post-Render Script

Run this script after all rendering.

Render nodes

  • Agent

    Writes 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.

  • Channel

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

  • Composite

    Renders images from a compositing network.

  • 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

    Exports animation from a geometry-based skeleton to an FBX file.

  • Filmbox FBX Character

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

  • Flipbook

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

  • 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.

  • Geometry Raw

    Generates raw binary 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.

  • Image

    Writes the output of a COP network to disk.

  • 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 CSV Exporter

    Export geometry attibutes to a CSV file.

  • Labs Flipbook Textures

    Renders, composites, and exports flipbook textures.

  • Labs Impostor Texture

    The impostor tool creates texture sheets to fake 3D objects in your game engine.

  • 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 Pyro Preview ROP

    A mantra wrapper for previewing pyro renders.

  • Labs RBD to FBX

    This tool allows for fast export of an RBD Sim to bone based FBX

  • Labs Sketchfab

    Uploads geometry to Sketchfab

  • Labs XYZ Pointcloud Exporter

    Export a pointcloud to XYZ file.

  • Labs ZibraVDB Compress

    Compresses a VDB sequence and caches it to disk as a single .zibravdb file.

  • MDD Point Cache

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

  • ML Example Raw

    Generates raw binary files for ML training from a SOP or DOP network.

  • 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.

  • Pre Post

    Renders ROPs before and after a main job.

  • 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 2.0