This page provides an overview of the setup and use of External Material Libraries (EML).


Overview


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;
  • Download  vraysettings.json file and place it in the Content folder of the V-Ray for Unreal plugin. (The default is C:\Program Files\Epic Games\VersionNumber\Plugins\VRayForUnreal\Content);
  • Open the the .json file and delete the # symbol to enable the EML functionalitythe in the line "#mtl_libraries" : ["Content/mtl_library/mtl_library.vrscene"];
  • 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.