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Naming points or primitives
This node sets an attribute (called
name by default) on the selected
points/primitives to a certain value. For example, you can select a
single face, or small set of faces, on some polygonal geometry, and
foo (that is, create a primitive attribute
name with the
foo) on the faces. You can then refer to the primitives in
subsequent nodes using
This is very similar to groups: using
similar to creating a group
foo and referring to it using
However, name attributes have two differences from groups:
Names are more efficient than groups. For example, you can assign different names to hundreds or thousands of individual faces, while creating hundreds of groups, each with a single member, would be problematic.
Names enforce the constraint that each primitive can only have one name value at a time (that is, a primitive can’t be included in both
@name=bar), whereas a primitive can be a member of multiple groups. This constraint may be useful in some workflows.
Mantra uses named primitives to determine how to bind volumes to shaders during rendering. The Volume Vop node uses named primitives to determine binding if Autobind is on.
Renaming existing named groups
In addition to assigning names to points and primitives, you can also use this node to rename existing named groups, using the Global, From, and To parameters. This works like the Attrib String Edit node. See the help for Attrib String Edit for more information.
The name of the attribute to create or edit. The default is
name, the attribute name mantra and the
Volume Vop node look for.
Whether to name points or primitives.
Name from Group
Assigns the name attribute to the corresponding name of the group the point or primitive is part of. If it is part of more than one group, the behaviour is undefined. The idea is to provide the inverse to the Partition SOP.
When naming from groups, only groups that match this pattern will be used. This avoids other material groups overwriting your desired partition group.
Number of Namings
The number of naming attributes to create. Click the Add icon.
The list of points/primitives to create/edit the attribute on. Normally this is filled in by Houdini from the viewport selection. See specifying groups for information on the format for specifying point and attribute numbers manually.
The attribute value to set on the points/primitives in the group.
For example, if Attribute is
name and this parameter is
foo, Houdini will create a
name attribute on each of the
points/primitives listed in Group and set it to
Whether to create/edit the attribute. This parameter lets you animate the operation of this node.
You can use the following parameters to rename existing named groups. See Attrib String Edit for more information.
When this option is on, the From pattern is replaced for each occurrence in the string. When off, only the first occurrence is replaced.
The string pattern to rename.
The replacement pattern for the From string.
The following examples include this node.
This example demonstrates how the Gas Equalize Volume dop can be used to preserve the volume in a fluid simulation.
This example shows how to setup the Bake Volume SOP to compute the lightfield created by the shadowing of a fog volume. It then exports the fields properly to be rendered in Mantra by a constant volume shader.
This example shows how to detect the overlapping regions of many incoming volumes procedurally using Volume SOP and Volume Merge SOP.