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This node can import Houdini VOP materials from a VOP network (such as
/mat). Alternatively, this node contains a VOP subnet as a convenient place to define USD materials (see USD materials below).
This node can "auto import" all the materials in the VOP network.
If you want to re-do importing all materials (for example, to grab new materials), click Clear in the multi-parm, then click Auto-fill materials again.
Even though this node allows you to assign the material at the same time you import it, we recommend you use a separate node (Material Linker or Assign Material) to assign materials. Keeping the two operations separate makes your network easier to understand for others.
Inside the Material Library LOP, the VOP nodes, their parameters, and inputs represent USD shaders, their attributes and input connectors. For example, a Principled Shader VOP represents a Karma material, and the Pxr Surface VOP represents a USD RenderMan shader.
The Collect VOP can gather several shaders for different renderers to create a USD material that contains all of them.
You can connect the shader VOPs can be connected to one another, and the node will translate these as USD shader connections. (For example, if you connect the output of a USD UV Texture VOP to the input of USD Preview Surface VOP.)
To import materials from inside this node, set the Material network to
. (a single period).
Node path to the VOP network containing material nodes to import. The node looks for materials here when you click Auto-fill materials. Set this to
. (a single period) to use the VOP subnet inside this node.
The default parent scene graph path of newly created materials. This is prefixed to the material names to get the material prim path when you click Auto-fill materials.
Click this to automatically create instances of the multi-parm for each material node in the Material network.
Auto-generate Preview Surface Shaders
When possible, this node will generate a USD Preview Surface shader primitive. This shader type is part of the USD standard and should be implemented by all USD renderers, so this shader (which may be an approximation of the original shader) should show up in any renderer, even if the renderer doesn’t understand the original shader type.
Allow Shader Parameter Animation
When it is turned off, all USD values are assumed non-animatable and will be authored at a default time code. And, with this option turned on, shader node parameters that are time-dependent will get translated to USD values at non-default time codes, while time-independent parameters will still author a value at a default time code.
Note, checking parameter time dependency can be costly and may add up to a large portion of the shader translation time. Since the vast majority of shader nodes don’t have animated parameters, this toggle is off by default to save the work involved in checking it.
Parent Primitive Type
If the intermediate prims in a material path don’t exist, the node will create them. This controls the type of the intermediate prims this node creates.
Material Path Prefix
This is automatically prefixed to any material paths that are not absolute (do not start with a slash). This lets you specify relative material paths in the multi-parm, and set their common parent hierarchy in this one parameter.
Number of Materials
The number of materials to import. Set the number or click the plus and minus buttons to add or remove material imports.
Include Only VOPs with Material Flag Set
If Material VOP is a pattern, this excludes nodes that don’t have the Material flag on. Default is off.
The Houdini node path to a VOP node representing a shader or material. This can be a node pattern, in which case this node will import all matched nodes as USD materials.
The USD scene graph path at which to create the material prim. If this is an absolute path (starts with a slash), it is used as-is. If this path is relative, it is relative to the path in the Material path prefix parameter.
Assign to Geometry
When this is on, you can assign the newly imported material to USD geometry prims using the Geometry path parameter below.
When Assign to geometry is on, assign the newly imported material to the primitives listed in this parameter.