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| Since | 18.0 |
This node reads a USD file or LOP node and creates work items based on search criteria. The search is done on the composed stage of the specified input USD or LOP.
TOP Attributes ¶
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string |
The name of the primitive. |
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string |
The full path to the primitive. |
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float3 |
The frame associated with the USD data. |
Parameters ¶
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.
The input the node reads to create the work items.
USD
Determines the source of the USD file or LOP node.
Custom File Path
Uses the USD file specified by the custom file path.
Upstream Output File
Uses the output file produced by the upstream work item as the path to the USD file.
LOP Node
Reads the composed stage from the specified LOP node.
File Tag
The data tag that identifies the result from the upstream work item.
This parameter is only available when USD is set to Upstream Output File.
File Path
The path to the USD file to be read.
This parameter is only available when USD is set to Custom File Path.
Population Mask
When enabled, this parameter can be set to a space-separated list of primitive paths that should be used as a population mask when loading the .usd file.
This parameter is only available when USD is set to either Custom File Path or Upstream Output File.
Add File Path to Outputs
When on, this parameter determines whether or not the file path should be added as an output file to work items on this node.
This parameter is only available when USD is set to either Custom File Path or Upstream Output File.
LOP Path
The path to the LOP node from which to read the composed stage.
This parameter is only available when USD is set to LOP Node.
Evaluate with Work Item Attributes
Turn on when your LOP network uses @attribute expressions to pull values from work items (for example, like with wedging). If you use @attribute expressions, the node needs to cook the LOP separately for each work item. If you do not use @attribute expressions, the node only needs to cook the LOP once.
This parameter is only available when USD is set to LOP Node.
The primitives and their metadata that the node should import.
Import Primitives
The Primitive Matching Pattern to apply to the specified input stage.
Encode Imported Names
When on, the names of imported attributes are encoded so that they meet the requirements of PDG attribute names. This uses the same rules as the hou.text.encodeAttrib method.
Prim Path Attrib
When on, adds the specified string attribute containing the primitive path to each work item.
Prim Name Attrib
When on, adds the specified string attribute containing the primitive name to each work item.
Frame Range Attrib
When on, adds the specified float attribute containing the USD frame range to each work item.
Set Item Index To
Determines what the work item index is set to.
Primitive Index
The index of generated work items is set to the index of the primitive for that work item within the overall list of imported primitives.
Upstream Item Index
Sets each work item’s index to the upstream item’s index.
For settings that generate multiple work items for each incoming work item, this creates duplicate index values.
Flatten Indices
When Set Item Index To is Primitive Index, this parameter determines whether or not work item indices created from element numbers should be flattened. If this parameter is enabled, the indices in the node are guaranteed to be unique across all work items. Otherwise, it’s possible for work items to have the same index if the node is importing USD data from multiple upstream work items.
For example, this parameter is useful when using a 
Wedge to import the same LOP network with different attribute variations, or when importing multiple .usd files found on disk using a 
File Pattern.
Evaluation Time
Determines how attribute keyframe values from the input stage are interpolated.
Work Item Frame
Uses the frame on the generated work item.
Custom Time
Uses the given time in seconds.
Houdini Time
Uses the Houdini playbar time.
Custom Frame
Uses the given frame value.
Custom Range
Uses the given frame range. If the USD parameter is set to LOP Node, the LOP node is cooked once for each frame in the range.
Custom Frame/Time
The value of the Custom Time or Frame to use when sampling the USD stage.
Custom Range
When Evaluation Time is set to Custom Range, this parameter determines the frame range to use when evaluating the target LOP node or input .usd file.
Strip Layers Preceding Layer Break
When on, any layers preceding a 
Layer Break LOP node connected directly or indirectly to the requested LOP node will be stripped from the USD stage before importing the stage.
This parameter is only applicable when the input is a LOP node.
Controls which attributes are imported from the primitives that matched using Import Primitives.
Import Attributes
Specifies the attribute pattern to use when identifying which USD attributes to extract and then extracts those attributes.
Note
The :‹type› syntax is not supported.
Attribute Names
When on, this parameter specifies the name of the work item attribute that should contain the list of all imported USD attribute names.
Import Samples
Determines how the node should import attributes with multiple samples. When importing multipole samples for an attribute the values are stored on the work item as an array. If the attribute data itself is already in an array or vector format, then the values are flattened. For example, a vector3f attribute with five samples would resolve to a float array attribute with fifteen entries on the work item.
Current
Only imports the current sample for the attribute, based on the evaluation time.
Custom Range
Imports samples over a custom range.
All
Imports all samples for the attribute.
Sample Range
When Import Samples is set to Custom Range this parameter determines the sample range. The end points of the range are both inclusive.
Sample Constant Attributes
When Import Samples is set to Custom Range, this parameter determines whether sampling should be applied to all attributes. If the toggle is off then the sample range is only applied to attributes that actually have multiple samples.
Namespace Cutoff
By default, this node imports USD attributes using their full names, including any namespace(s). To trim namespaces from the imported attribute names, set this parameter to a non-zero value. A positive value indicates the number of namespace levels that should be removed, beginning from the left side of the attribute name. A negative value indicates that the cutoff point should be determined starting from the right side of the attribute name. The right-most segment of the name (the actual attribute name) is never removed.
For example, for a USD attribute named primvars:karma:pixelsamples the following table shows the possible work item attribute names based on the cutoff index:
Namespace Cutoff |
Attribute Name |
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Controls which relationships and variants are imported from the primitives that matched using Import Primitives.
Import Relationships
Specifies the attribute pattern to use when identifying which USD relationships should be copied to work item attributes.
Note
The :‹type› syntax is not supported.
Relationship Names
When on, this parameter specifies the name of the work item attribute that should contain the list of all imported USD relationship names.
Import Variants
Specifies the attribute pattern to use when identifying which USD variant sets should be imported into work item attributes
Note
The :‹type› syntax is not supported.
Order of Results
Specifies the order of the variant names in the string array attribute create for each imported variant set.
Variant Names
When on, this parameter specifies the name of the work item attribute that should contain the list of all imported USD variant set names.
Examples ¶
USDImport Example for USD Import Data TOP node
This example demonstrates how to generate work items from primitives in a LOP stage using the USD Import TOP node.
| See also |
ROP USD Output
USD Render
Geometry Import
