Create USD Unreal material binding

gistfile1.txt

from pxr import Usd, UsdGeom, Sdf, UsdShade
import os

##############
# Assuming a single mesh usd file
# Create a material and a binding to an Unreal material location so it gets automagically assined on load
# Remove the existing material assignment if one is found  in the file
#
##############


def findNodes(stage):
    look = None
    for x in stage.Traverse():
        if x.GetTypeName() == 'Mesh':
            geo = x
        if x.GetTypeName() == 'Material':
            if x.GetParent().GetTypeName() == "Scope":
                look = x.GetParent()
    return geo, look

def addUnrealMtlAttrs(stage, prim, mtl):
    primPath = prim.GetPath()
    _material = stage.DefinePrim("%s/UnrealMaterial"% primPath, "Material")
    _shader = stage.DefinePrim("%s/UnrealMaterial/UnrealShader"% primPath, "Shader")
    sourceAsset= _shader.CreateAttribute('info:unreal:sourceAsset', Sdf.ValueTypeNames.Asset, variability = Sdf.VariabilityUniform)
    sourceAsset.Set(mtl)
    implementationSource = _shader.CreateAttribute('info:implementationSource', Sdf.ValueTypeNames.Token, variability = Sdf.VariabilityUniform)
    implementationSource.Set('sourceAsset')
    outputsToken = _shader.CreateAttribute('outputs:out', Sdf.ValueTypeNames.Token)
    connect = _material.CreateAttribute("outputs:unreal:surface", Sdf.ValueTypeNames.Token)
    connect.SetConnections([outputsToken.GetPath()])
    UsdShade.MaterialBindingAPI(prim).GetDirectBindingRel().SetTargets([_material.GetPath()])

def processFile(srcFile, unrealMtlPath, dryRun = True):
    print("Processing %s" % srcFile)
    dstDir = "%s_processed" % os.path.dirname(srcFile)
    dstFile = "%s/%s" % (dstDir, os.path.basename(srcFile))
    stage = Usd.Stage.Open(srcFile)
    primMesh, primLooks = findNodes(stage)
    if primLooks:
        print("\tRemoving Looks at %s" % primLooks.GetPath())
        stage.RemovePrim(primLooks.GetPath())
    else:
        primMesh.ApplyAPI(UsdShade.MaterialBindingAPI)
    print("\tAssigning unreal mtl to %s" % primMesh.GetPath())
    addUnrealMtlAttrs(stage, primMesh, unrealMtlPath)
    print("\tOutput to: %s"% dstFile)
    if not dryRun:
        print("\t\tExporting %s\n" % dstFile)
        os.makedirs(dstDir, exist_ok = True)
        stage.Export(dstFile)
    else:
        print("\t\tNot saving: dryRun is True\n")

for root, dirs, files in os.walk("./usd/cmpt/walls_v20"):
    unrealMtlPath = "/Game/Set/mtl/mtl_env_houses.mtl_env_houses"
    for f in files:
        if f.find("usd")>0:
            srcFile = os.path.join(root, f)
            processFile(srcFile, unrealMtlPath, dryRun = 1)

exit()

LogPython: PRIM_MESH_PATH:/abcd/baseCussion_grp/baseCussion01__leather_leather_geo
LogPython: MATSG_PATH:/Looks/M_chair_body_mtlSG
LogPython: MTL_PATH:/Looks/M_chair_body_mtlSG/M_chair_body_mtl
LogPython: UNREAL MATERIALS PATH:/Game/bpll/M_chair_body_mtlSG.M_chair_body_mtlSG

line 27 sourceAsset.Set(mtl) == > i got an error
LogPython: Error: File "", line 27, in addUnrealMtlAttrs

LogPython: Error: pxr.Tf.ErrorException:
LogPython: Error: Error in 'pxrInternal_v0_21__pxrReserved__::UsdStage::_SetValueImpl' at line 5981 in file C:\Users\MattJohnson\Developer\USD\pxr\usd\usd\stage.cpp : 'Type mismatch for </Looks/M_chair_body_mtlSG/M_chair_body_mtl.info:unreal:sourceAsset>: expected 'SdfAssetPath', got 'TfPyObjWrapper''