Houdini 18.0 Nodes TOP nodes

Partition by Frame TOP node

Partitions work items based on their frame

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Partitions work items based on their frame and the selected frame rounding mode.

You can use this node to combine multiple subframes into a single frame unit, or to separate frames from different wedge variations. This allows you to run a simulation with integer frames that is internally loading source geometry at subframes.

For example, you can use this node to help with the following:

Parameters

Use Dynamic Partitioning

When this toggle is enabled the partitioner will wait for all input work items to be generated before partitioning them. If the input work items are dynamic, this means the partitioner will have to wait for and depend on the parent(s) of those items.

Merge Input Attributes

When this toggle is enabled the partitioner will merge the attributes of the work items in each partition and export them to the partition itself.

Frame

Frame Rounding

When partitioning work items with fractional frames, determines how the frame is converted to an integer for partitioning.

Round Down

Rounds the frame value down to the nearest integer. For example, values from 1.0 to 1.9 are treated as frame 1.

Round Up

Rounds the frame value up to the nearest integer. For example, values from 1.1 to 2.0 are treated as frame 2.

Round Nearest

Rounds the frame value to the nearest frame. For example, values from 1.0 to 1.49 are treated as frame 1.0, and values from 1.5 to 2.0 are treated as frame 2.

Split by Attribute

When this parameter is enabled, work items will be split into separate groups before the items are partitioned. This parameter specifies the name of the attribute on the input work items that should be used to determine those groups. For example, you can set this parameter to wedgeindex in order to keep wedge variations in different partitions.

The following extra steps are performed when using a split attribute

  • The node looks up the value of the split attribute for each input work item.

  • The work items are then grouped based on their split attribute value. One group is created for each unique value of the split attribute.

  • The regular partitioning process is applied to each of the group of work items. Work items in different groups will always be in different partitions. Groups are processed in ascending order of their split attribute value.

On Missing Attribute

When Split by Attribute is enabled this parameter determines how the node should handle an input work item that does not have the split attribute.

Ignore Work Item

Input work items that are missing the split attribute won’t be added to any of the partitions.

Add to Partitions with Matching Frame

Input work items that are missing the split attribute will be added to partitions that have the same frame as the work item.

Add to All Partitions

Input work items that are missing the split attribute will be added to all partitions produced by the node.

Use Frame for Partition Index

When on, the partitions that are created have their indexes set to the frame number assigned to the partition.

When off, the partitions have their indexes set from 0 up to the number of partitions created.

When Wedge Attribute is also on, and you want to split frames by wedge index, it isn’t always possible to set the partition index to the frame number. That is because there may be different wedge variations with the same frame number. In this case, the node maintains a unique index for each partition, but the indexing begins at the first frame in the first wedge instead of at 0.

Ignore Items With No Frame

When on, work items with no frame value are ignored. Otherwise, an error is produced when you try to partition a work item that does not have a specified frame value.

Advanced

These are advanced parameters that give you a finer level of control over the behavior of the partitioner.

Auto Remove Stale Dependencies

When recooking the node, indicates that the partitioner should remove old dependencies if the partitioning scheme changes as a result of the cook.

Force Re-Evaluation on Cook

Forces the partitioner to re-evaluation the partitioning scheme even if all of the work items are already cooked and no new work items have been added.

Dirtying Mode

The dirty mode parameter offers fine grained control over when a partition is dirtied and the effects on child items when that occurs. This parameter is particularity useful for working around some of the limitation of using dynamic partitioning.

Standard

A given partition will be dirtied when any of the work items in the partition are dirtied. In the case of dynamic partitioning, if any ancestor of a dynamic work item in a partition is dirtied, then All partitions will be dirtied.

When a partition is dirtied all of its children are deleted.

Non-destructive

The same dirtying behavior as Standard, except when a partition is dirtied its children will be dirtied instead of deleted.

Mapping Standard

A given partition will only be dirtied if an item in the partition is dirtied or if the partition’s contents changes as a result of a recook. When the partition is dirtied, any child work items will be deleted.

Mapping Non-destructive

The same as Mapping Standard, except when a partition is dirtied its children will be dirtied instead of deleted.

Sort Contents By

Determines the order that work items are sorted when accessing the partitions on this node. This also affects the sort order of output files on the partition.

None

No sorting is applied - the work items in the partition are handled in no particular order.

Work Item Index

Work items in the partition are sorted based on their index

Input Node Order

Work items in the partition are sorted based on the order of inputs nodes wired into the partitioner itself. If two work items are from the same input, they are then sorted by index.

Attribute

Work items in the partition are sorted based on the attribute specified in the Sort Attribute parameter.

Sort Direction

Determines whether the work items in this node’s partitions are sorted in ascending or descending order.

Sort Attribute

When Sort Contents By is set to Attribute, this parameter is used to determine the name of the attribute to sort by.

Partition When

This parameter is only enabled when using dynamic partitioning. It controls when the partitioning step is performed on the input work items.

Input Items Are Generated

Inputs are partitioned once all of them have been generated.

Input Items Are Cooked

Inputs are partitioned once all of them are cooked. This is required when the partitioning scheme is based on the results of the work items' execution.

This makes this partitioner behave like a Wait for All except that it may create multiple partitions.

Partition Target

This parameter is only enabled when using dynamic partitioning. When the target is set, the partition scheme will be applied to the work items in the target TOP node instead of the input work items.

The target TOP node must be a processor in the same graph above this node, and there cannot be any other mappers or partitioner between this node and the target.

Examples

example_top_partitionbyframe Example for Partition by Frame TOP node

This example demonstrates how to use the partition by frame node in PDG/TOPs.

See also

TOP nodes