CreateMaterial.py

import omni.usd
from pxr import Usd, UsdGeom, UsdPhysics, UsdShade, Sdf, Gf, Tf

# Get stage.
stage = omni.usd.get_context().get_stage()

# Create sphere.
spherePath = "/World/sphere"
sphereGeom = UsdGeom.Sphere.Define(stage, spherePath)
sphereGeom.CreateRadiusAttr(20.0)
spherePrim = stage.GetPrimAtPath(spherePath)
spherePrim.CreateAttribute("refinementEnableOverride", Sdf.ValueTypeNames.Bool).Set(True)
spherePrim.CreateAttribute("refinementLevel", Sdf.ValueTypeNames.Int).Set(2)

# Create material scope.
materialScopePath = "/World/Materials"
scopePrim = stage.GetPrimAtPath(materialScopePath)
if scopePrim.IsValid() == False:
    UsdGeom.Scope.Define(stage, materialScopePath)
    
# Create material (UsdPreviewSurface).
materialPath = "/World/Materials/mat1"
material = UsdShade.Material.Define(stage, materialPath)
pbrShader = UsdShade.Shader.Define(stage, f"{materialPath}/PBRShader")
pbrShader.CreateIdAttr("UsdPreviewSurface")
pbrShader.CreateInput("diffuseColor", Sdf.ValueTypeNames.Color3f).Set((1.0, 0.2, 0.0))
pbrShader.CreateInput("roughness", Sdf.ValueTypeNames.Float).Set(0.4)
pbrShader.CreateInput("metallic", Sdf.ValueTypeNames.Float).Set(0.0)

# Connect PBRShader to Material.
material.CreateSurfaceOutput().ConnectToSource(pbrShader.ConnectableAPI(), "surface")

# Bind material.
UsdShade.MaterialBindingAPI(spherePrim).Bind(material)