Houdini 21.0 Nodes Geometry nodes

USD Configure Prims from Points geometry node

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Since 21.0

This node sets the special point attributes so that SOP Import LOP turns those points into USD Prims, when loading SOP geometry into LOPs.

The standard instance SOP attributes are used to compute the translated points into USD Xforms.

Requirements

When you connect this node’s input to a polygon object like a grid, you’ll get a warning saying that @usdprimtype must be authored on free-floating points. The message means that only points without any connected geometry are accepted and you have to delete the unsupported geometry:

One way to do this is to place an Add SOP between the geometry and the USD Configure Prims from Points SOP. On the add node’s Points tab, turn on Delete Geometry But Keep the Points. Note that it’s not enough to group connected points, because they're still tied to their respective polygons. Of course, (sub)groups from free-floating points are supported.

  • Points from the Scatter SOP or Scatter and Align SOP are already free-floating and don’t need any further processing. This also applies to particles from POP networks.

  • With points from Vellum-based sources, you have to consider their origin. If the Vellum points are created from geometry, you have to isolate the points, for example with the mentioned Add SOP. If the points already originate from a free-floating source, you can use them as they are.

Another warning informs you if the points are missing important attributes: @path or @name must be authored, along with @usdprimtype, for SOP Import to convert these points into USD prims.

In this case we recommend using the configure prims node’s own Path (on by default) and Name attributes, because they're already preconfigured. You can change the default entries to your requirements or use the Name SOP.

Parameters

Group

The point group on which to operate.

Prim Type

Authors the usdprimtype string attribute, specifying which prim type this point should become when imported into LOPs.

The menu provides a limited set of common options, but any valid USD prim type can be authored.

Path

Authors the path string attribute, which declares the scene graph location of the prim represented by this point.

Name

Authors the name string attribute. This gets appended to the Path Prefix on SOP Import LOP, and the combined results in the scene graph location of the prim represented by this point.

Prim Type Attributes

These are specific properties based on the given Prim Type, many of which are shared between the different schemas.

Note

Each of these prim type parameters has an action button, that appends a SOP node for randomizing the values per-point.

Color

Sets the Cd attribute on the points, which gets converted to primvars:displayColor. Applies to nearly all gprims.

Size

Sets the uniform size of cube prims.

Length

Sets the length of prims like cylinders, along the Z-axis.

Height

Sets the height of prims such as rectangle lights, along the Y-axis.

Width

Sets the width of prims such as rectangle lights, along the X-axis.

Top Radius

Sets the top radius of prims such as capsules.

Bottom Radius

Sets the bottom radius of prims such as capsules.

Radius

Sets the uniform radius of prims such as spheres.

Intensity

Sets the power output of the light on a linear scale.

Exposure

Scales the power output of the light exponentially as a power of 2, similar to an F-stop control.

General Properties

Active

Whether the prim will be authored as active or inactive. Authoring no value results in an active prim.

Visibility

Authors whether a prims is invisible, or inherits visibility from its ancestors.

Purpose

Sets the render purpose of the prims in USD.

Kind

Sets the usdkind string attribute as the prim’s kind.

API Schemas

The usdapischemas point string array attribute can specify one or more API schemas to be applied to the prim.

Materials

Warning

Material assignments can be made on the points, but require Bind Materials to be enabled on the SOP Import LOP. This means that unlike most of the attributes here, material bindings don’t work with the SOP Geometry file format plugin, when you sublayer or reference a bgeo file directly.

Material Path

The USD prim’s binding relationship will point to this location. This path is usually a path already on the LOP stage. If Reference File is set, the material reference will be created at this prim path.

Reference File

A material can come from a file on disk. This is the path to that USD layer, and the SOP Import LOP will create the reference to the file.

Reference Prim

Path to the specific material you wish to reference from the Reference File

Custom Properties

Primvars

Creates custom primvar attributes. The only difference from creating SOP attributes elsewhere, is here you can add namespaces to the primvar names, and this node will encode them for you.

Attributes

Attributes in USD are typically associated with a specific prim type, and are not inheritable from ancestors like primvars.

See also

Geometry nodes