Add an Inherit

An Inherit is a composition arc that enables a prim to contain all of the scene description contained in the base prim it inherits. This enables users to author opinions on the base prim that are broadcast to all the prims that inherit it. The Inherit USD Glossary entry explains the nuances of the composition arc in more detail.

USD Python

This code sample shows how to add an Inherit arc to a prim. A single prim can have multiple Inherits.

from pxr import Usd

def add_inherit(stage: Usd.Stage, prim: Usd.Prim, class_prim: Usd.Prim):
    inherits: Usd.Inherits = prim.GetInherits()
    inherits.AddInherit(class_prim.GetPath())

#############
# Full Usage
#############

from pxr import Sdf, UsdGeom

# Create an in-memory Stage with /World Xform prim as the default prim
stage: Usd.Stage = Usd.Stage.CreateInMemory()
default_prim: Usd.Prim = UsdGeom.Xform.Define(stage, Sdf.Path("/World")).GetPrim()
stage.SetDefaultPrim(default_prim)

# The base prim typically uses the "class" Specifier to designate that it
# is meant to be inherited and skipped in standard stage traversals
tree_class: Usd.Prim = stage.CreateClassPrim("/_class_Tree")
tree_prim: Usd.Prim = UsdGeom.Mesh.Define(stage, default_prim.GetPath().AppendPath("TreeA")).GetPrim()

add_inherit(stage, tree_prim, tree_class)

usda = stage.GetRootLayer().ExportToString()
print(usda)

# Check to see if the inherit was added
inherits_list = tree_prim.GetInherits().GetAllDirectInherits()
assert tree_class.GetPath() in inherits_list

USDA

This is an example USDA result adding an Inherit Arc to a prim.

#usda 1.0
(
    defaultPrim = "World"
)

def Xform "World"
{
    def Mesh "TreeA" (
        prepend inherits = </_class_Tree>
    )
    {
    }
}

class "_class_Tree"
{
}