Houdini 17.5 Nodes TOP nodes

HDA Processor TOP node

Creates work items that cook a digital asset

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This node generates work items that are cooked using the HDAProcessor executable that ships with Houdini. The attributes of the work item are applied as parameters to the asset.

TOP Attributes

HDA Processor will create attributes on work items for all spare parms added to the HDA Parameters folder on the node. Additionally, it will create the following built-in attributes:



The path to the digital asset that will be cooked by the work item



The operator type within the digital asset. If an operator type is not specified using the Operator Type parameter this attribute will be set to empty string, and the work item will use the first operator in the .hda.



The number of input files, as specified in the Number of Inputs parameter.


string array

The input file(s) that should be passed to file SOP inputs wired into the .hda. The length of the string array will match the value of the Number of Inputs parameter and the fileinputs attribute.



Set to 1 if Write Geometry is turned on, else 0.



The output path where geometry will be written, if Write Geometry is turned on.



The result data tag associated with the output path.



Set to 1 if Save Debug .hip File is turned on, else 0.




Template Node

An instance of an .hda in the current Houdini session. The HDA Processor will cook instances of that asset and use its parameter values as defaults.

HDA File

A relative or absolute path the HDA to cook.

Operator Type

The operator type to select form within the HDA. If no operator type is specified, HDA Processor will pick the first type it finds when cooking the asset.

Update HDA Parameters

When pressed, this button updates the HDA Parameters section

Filter HDA Parameters

Opens a dialog that can be used to configure which parameters from the asset should be promoted onto this node.

Auto Enabled HDA Parameter Expressions

When this parameter is turned on, empty expressions will automatically be set on the HDA Parameters

Work Items

Work Item Generation

Whether this node generates static or dynamic work items. You should generally leave this set to "Automatic" unless you know the node’s work items can be computed statically, or that they need to be generated dynamically.


This node always creates dynamic work items: it waits until the upstream work items are known, and generates new work items from the upstream work items.


This node always creates static work items: it creates the number of work items it thinks it needs based on the parameters (and any upstream static items) before the network runs.


If the input is static (a static processor, or a partitioner with only static inputs, or a mapper), this node generates static work items, otherwise it generates dynamic work items.


The number of work items to create


When enabled, the priority of the work items created by this node. The default priority is 0.

Batch Size

When enabled, indicates that this node should generate batch work items and sets the batch size to this parameter’s value.


When this toggle is enabled, the work items generated by this node will be sequentially dependent on each other.

Asset Input

Create File SOP Inputs

When this parameter is enabled, one or more file SOPs will be instantiated and wired as inputs to the asset. This can be used to chain multiple HDA Processor nodes together more easily.

Number of Inputs

The number of input file SOPs to create. By default, the file SOP will use the nth input file to the work item.

Custom Input File #

By default, the input file that corresponds to this file’s number will be used as the input to the file SOP. This parameter can be enabled to provide a custom input file path.

Asset Output

Write Geometry

When this toggle is turned on, HDA Processor will output geometry to disk from the display node in the asset. If the asset contains a COP network or a ROP network, it may be useful to turn this off.

Output File Name

When writing geometry, this is the name of the output file.

Output Tag

When writing geometry, this is the tag assigned to the result file

Save Debug .hip File

When this toggle is enabled, a debug .hip file containing the instantiated asset, the file SOP and all parameter values will be written to disk. This is useful for tracking down problems with the asset.

HDA Parameters

This section of the node is filled in automatically based on the parm interface of the selected digital asset. Parameters set here will be copied to work item attributes and applied to the asset when its cooked.


example_top_hdaprocessor Example for HDA Processor TOP node

This example demonstrates how to use HDA Processor to distribute HDAs using PDG/TOPs.

The following examples include this node.

example_top_errorhandler Example for Error Handler TOP node

This example demonstrates how to use the Error Handler node in PDG / TOPs.

example_top_hdaprocessor Example for HDA Processor TOP node

This example demonstrates how to use HDA Processor to distribute HDAs using PDG/TOPs.

example_top_topfetch Example for TOP Fetch TOP node

This example demonstrates how to use Top Fetch to fetch results from other top networks.

example_top_topfetchinput Example for TOP Fetch Input TOP node

This example demonstrates how to use Top Fetch to fetch results from other top networks (using Top Fetch Input).

See also

TOP nodes