When importing a USD file some of the meshes gets the wrong materials assigned. I have looked in the .usda file and the material relationship looks ok there. I have also imported the same USD file in Houdini and the material assignment is ok there aswell. What can be the issue here?
I also would like the option when importing .usd files to disable the prefix “MI_” and the suffix “_1_TwoSided”. I would prefer to keep the material name as it is in the usd file. If we could get an option to disable this it would be awesome!
Steps to Reproduce
In unreal 5.7.4 import the “Material_Sample_574.usd” file (import into level) and inspect the material assignment. Each mesh should have a material with the same name as the mesh. Some of the meshes gets the wrong material assigned. I have provided an image that describe the issue “material_name_issue.jpg”. I have also provided an .fbx file for reference.
I have also listed which meshes that gets the wrong material. see “name_info.txt”
1) The USD importer will try to minimize the number of assets and reuse them if their data are the same. You can turn off this behavior through the “Share Assets for Identical Prims” setting under the “USD Options” section;
2) In UE, it is the material that is double-sided while in USD it’s the mesh. So to support single- and double-sidedness, UE creates 2 material instances: one standard, single-sided material that uses the USD material name and a double-sided material with the _TwoSided suffix appended to the USD material name to differentiate from the former. So this suffix can’t be turned off. However, if the mesh doesn’t need to be 2-sided, you can turn that off and UE will apply the singled-sided material to it;
3) For the prefix in the asset name, if you can modify and compile UE yourself, then you can control the prefixes from UsdUnreal::ObjectUtils::GetPrefixedAssetName in USDObjectUtils.cpp. For the material prefixes, look for
else if (AssetClass->IsChildOf(UMaterialInterface::StaticClass()))
It is unlikely we’ll add an option for this soon but I’ll log a jira to track this issue.