This page provides an overview of the setup and use of External Material Libraries (EML).
If you would like to use a material that is not yet supported, you can take advantage of the functionality to map Unreal materials to V-Ray materials created with another V-Ray plugin (e.g. V-Ray for Maya, V-Ray for 3ds Max, etc.). For this to work, the materials have to be exported as a .vrscene file (this would be the EML file). The mapping works by matching the name of a material in Unreal to the name of a material in the EML file. In addition, the materials in the EML file need to have a scene_name parameter set. This is the that is used to match a material in Unreal.
EML vrscene Setup
To use the External Material Libraries you have to do the following:
- Create a material in an application that uses V-Ray as a render engine (e.g. 3ds Max, Maya);
- Export the material to a .vrscene file;
- Open the generated vrscene with a text editor (e.g. Notepad);
- Locate your material. (e.g. MtlSingleBRDF NAMEOFMATERIAL);
- Make sure you have a scene_name= parameter in the MtlSingleBRDF properties with the material's name;
- Open the vraysettings.json file located in the Content folder of the V-Ray for Unreal plugin. (The default is C:\Program Files\Epic Games\VersionNumber\Plugins\VRayForUnreal\Content);
- In the json file, locate the line "#mtl_libraries" : ["Content/mtl_library/mtl_library.vrscene"];
- Delete the # symbol to enable the EML functionality;
- Replace Content/mtl_library/mtl_library.vrscene with the path of your vrscene with the material(s) you wish to use at render time;
- In Unreal, create a V-Ray Material Instance and name it as the material in the vrscene.
For more information, see the Advanced Material Workflow QuickStart.