This page provides information on the MDL Material.
Overview
The VRayMDLMtl material loads NVIDIA Material Definition Language files (.mdl) and renders them directly with V-Ray. The MDL Material is not supported in Maya 2015 on Mac OS X. |
The MDL Material does not work within Distributed Rendering at this time. |
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||Right-click on the geometry|| > Assign New Material... > VRay section > VRay Mtl MDL

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||V-Ray Shelf|| > Right-click to Create V-Ray Materials button > VRay Mtl MDL 
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||Hypershade|| > Window tab > Create... > VRay section > VRay Mtl MDL

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Installed Material Library
The following MDL material files are included when installing V-Ray for Maya 3.6. They are located in Local Disk (C:) > Program Files > Chaos Group > V-Ray > Maya 20yy for x64 > mdl.
Aluminum Anodized |
Architectural
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Asphalt
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Carbon composite
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Carpet Berber White
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Ceramic Tiles Small
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Chrome |
Coated Flipflop Paint |
Coated Flint Glass |
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Colored Wax |
Concrete |
Concrete Polished |
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Copper |
Granite Black |
Mahogany Floorboards |
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Marble White |
Metal Examples |
Noise Flow Glossy |
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Noise Perlin Glossy |
Noise Worley Glossy |
Pattern Blended |
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Pattern Checker Glossy |
Porcelain |
Resin Polyurethane Matte |
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Rubber Studded Black |
Stucco |
Walnut Semi-Gloss |
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Basic Attributes
The Basic rollout provides the attributes used to set the path to the .mdl file that you wish to load into your chosen material, and an Update button needed to refresh the other attributes available, based on the material file used.

MDL file – Specifies the file path and .mdl file loaded.
Chosen material – If more than one material definition is included in the loaded .mdl file, the selected materials will be seen in the rollouts below.
MDL parameters– The Update button refreshes the additional material-specific attributes for the loaded .mdl file.
Parameters
Any additional material-specific attributes (if any) are listed in this rollout. The example below shows parameters for the Coated Flip-flop Paint material.
coated_flipflop_paint.mdl Parameters
MDL material attributes that can accept Render Nodes to map color values can now use File textures as input. Note: While other texture types may also be used, only File textures are guaranteed to work properly. |
Advanced Attributes

Max Ray Depth – Specifies the maximum reflection/refraction depth for the shader.
Remap Roughness – When enabled (default), determines whether the plugin expects squared values for GGX Roughness settings.
System Attributes

Filename – Specifies the file path and .mdl file loaded.
Importing NVIDIA vMaterials
In order for the MDL Material to correctly import NVIDIA vMaterials, the following two paths should be set in the environment variable shown below:
VRAY_MDL_PATH_MAYA20yy_x64=%PROGRAMFILES%\Chaos Group\V-Ray\Maya 20yy for x64\mdl;%PROGRAMDATA%\NVIDIA Corporation\mdl;%USERPROFILE%\Documents\mdl
where yy is the version of Maya installed.
Example:
VRAY_MDL_PATH_MAYA2018_x64=C:\Program Files\Chaos Group\V-Ray\Maya 2018 for x64\mdl;%PROGRAMDATA%\NVIDIA Corporation\mdl;%USERPROFILE%\Documents\mdl
Importing MDL Files from Substance Designer
In some cases, when using MDL files exported from Substance Designer, V-Ray may fail to load some modules. In order to load these modules, a folder needs to be set up before starting Maya, as expalined below:
1. Make a folder, for example, X:\MDL, that will act as the MDL repository. Put the MDL modules that are exported from Substance Designer into this folder.
2. Put the textures needed by the MDL materials in the same repository in their respective subfolder (for example, X:\MDL\MDL_Plywood_02).
3. Tell V-Ray where the MDL repository is by appending it to the VRAY_MDL_PATH_MAYA20yy_x64 environment variable.
4. Find the folder where Substance Designer keeps its MDL modules (usually C:\Program Files\Allegorithmic\Substance Designer 5\resources\view3d\iray but may differ from version to version) and append its path to the same environment variable.
In the end, the environment variable should look something like:
VRAY_MDL_PATH_MAYA2018_x64=C:\Program Files\Chaos Group\V-Ray\Maya 2018 for x64\mdl;C:\Program Files\Allegorithmic\Substance Designer 5\resources\view3d\iray;X:\MDL
References