Houdini 18.5 Nodes TOP nodes

Generic Generator TOP node

Generates work items with no attributes that run a command line.

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Since 17.5

You can use this node to generate work items with a command line generated by an expression. This node can also be useful when you want to start a network to generate a certain number of work items that don’t do anything (by leaving the command line blank), so that you can add attributes to them and use them to drive downstream nodes.

This node generates Item Count work items when it has no inputs. If the node has inputs, it generates Item Count work items for each upstream work item.

If you need more advanced functionality, use the Python Processor node instead.

Parameters

Processor

Generate When

Determines when this node will generate work items. You should generally leave this set to "Automatic" unless you know the node requires a specific generation mode, or that the work items need to be generated dynamically.

All Upstream Items are Generated

This node will generate work items once all of the input nodes have generated their work items.

All Upstream Items are Cooked

This node will generate work items once all of the input nodes have cooked their work items.

Each Upstream Item is Cooked

This node will generate work items each time a work item in an input node is cooked.

Automatic

The generation mode is selected based on the generation mode of the input nodes. If any of the input nodes are generating work items when their inputs cook, this node will be set to Each Upstream Item is Cooked. Otherwise, it will be set to All Upstream Items are Generated.

Sequential

Makes each generated work item depend on the previous one, so they run in sequence instead of simultaneously.

Copy Inputs to Outputs

When on, work items in the node automatically copy input files to their output file list. When off, the node assumes that the command line will attach output files to the work items.

Item Count

Sets the number of outgoing work items to generate for each incoming work item. If there are no incoming work items, the node generates this number of outgoing work items.

Index

By default, the node gives the generated work items sequential index attributes starting at 0. But when Index is on, the node generates custom index values from the expression specified in the parameter field.

Frame

By default, the generated work items inherit the frame attribute from the corresponding incoming work item. But when Frame is on, the node generates custom frame values from the expression specified in the parameter field.

Specify Command Using

Determines how the command line executable is specified.

Custom String

The command line executable is defined by a custom string.

Delay

The command line executable is defined by a delay time.

Command Builder

The command line executable is defined by a multiparm of command line args.

Command

Determines the command string for work items in this node.

This parameter is only available when Specify Command Using is set to Custom String.

Delay Time

Determines how long of a delay to use (in seconds). Work items in this node run a generic sleep/wait command line instead of running a custom command line. This parameter can be useful for simulating a slow workload to see how it affects the rest of the network.

For example, you can use this parameter to check whether nodes correctly wait for results before proceeding.

Base Command

Specifies the base command line. This parameter contains the executable and any simple arguments that don’t require the extra features available to the ones specified in the multiparm. The extra arguments specified by Extra Arguments are also appended to the end of the base command.

This parameter is only available when Specify Command Using is set to Command Builder.

Extra Arguments

Specifies the number of extra arguments to append to the Base Command.

Instead of specifying a command line string using a single expression, you can use this multiparm command builder to compose executable arguments.

You can drive these arguments with upstream files or work item attributes. You can also mark these arguments as command outputs, which adds the values of the arguments as output files on the work items.

If the argument data is in an array, the array values are automatically expanded into strings using a configurable separator.

This parameter is only available when Specify Command Using is set to Command Builder.

Argument Name

The name of the argument, such as -o or --output. When necessary, this name should include the '-'.

Argument Source

The source of the data passed to the argument.

Upstream Output Files

The values come from upstream output files.

Attribute Name

The values come from an attribute name.

Custom Value

The values come from a custom expression.

Input File Tag

Determines which tag to use when filtering the files.

This parameter is only available when Argument Source is set to Upstream Output Files.

Attribute Name

Specifies the name of the attribute to use for setting arg data. Since PDG can load the array attribute regardless of its length and convert it to a string, this is useful when looking up array data.

This parameter is only available when Argument Source is set to Attribute Name.

Argument Value

Determines what the argument value should be for each work item.

This parameter is only available when Argument Source is set to Custom Value.

Collapse Arrays To

Determines how arrays of files or attribute values should be handled when adding them to the command line. Arrays can be added as a space-separated list of values, a command separated list, or a list with a custom separator between entries. Alternatively, the entire argument can be copied for each entry in the array.

For example, given an input data array containing the entries ["example", "example1", "example2"] and an argument name of --input, the following expansions would take place:

Space-Separated String

executable --input "example" "example1" "example2"

Comma-Separated String

executable --input "example","example1","example2"

String with Custom Separator

Set to #.

Multiple Arguments

executable --input "example" --input "example1" --input "example2"

This parameter is only available when Argument Source is not set to Custom Value.

Array Separator

This parameter is only available when Collapse Arrays To is set to String with Custom Separator, and its field is located to the right of the Collapse Arrays To drop-down menu.

Specifies the separator used between entries in the array.

Attach Argument as Output File

When on, the value(s) from this argument are attached as output files on the work item.

Output File Tag

Specifies the file tag the node uses when attaching output files to the work item.

Schedulers

TOP Scheduler Override

This parameter overrides the TOP scheduler for this node.

Work Item Priority

This parameter determines how the current scheduler prioritizes the work items in this node.

Inherit From Upstream Item

The work items inherit their priority from their parent items. If a work item has no parent, its priority is set to 0.

Custom Expression

The work item priority is set to the value of Priority Expression.

Node Defines Priority

The work item priority is set based on the node’s own internal priority calculations.

This option is only available on the Python Processor TOP, ROP Fetch TOP, and ROP Output TOP nodes. These nodes define their own prioritization schemes that are implemented in their node logic.

Priority Expression

This parameter specifies an expression for work item priority. The expression is evaluated for each work item in the node.

This parameter is only available when Work Item Priority is set to Custom Expression.

Files

File Dependencies

A list of files that should be copied to the PDG working directory before the first work item in this node is executed. This can be used to ensure that supporting files like digital assets and custom scripts are available for the work item job.

The specified paths can be absolute or relative to HOUDINI_PATH.

Examples

GenericGenerator Example for Generic Generator TOP node

This example demonstrates how to use generic generators to both prototype setups and to run custom command line executables.

See also

TOP nodes