Page History

...

An important aspect of BRDFVRayMtl is the Fresnel reflection parameter (which is off by default when you create an instance, while it's on by default in V-Ray for 3dsMax). When it's enabled reflection amount depends on the angle of incidence. Glazing angles produce more reflection than looking head-on at the surface. This changes the conclusions we made above about how energy is distributed in the layers of the material. Even with 100% reflection (white color) some of the energy will go through to the reflection and diffuse layer. Fresnel reflections are a must for physically plausible materials. For Fresnel you need to set a correct index of refraction (IOR), even if the material doesn't refract any light. For example metals have very high IORs.

BRDFVRayMtl also has a translucency option, but you should use BRDFSSS2 instead for sub-surface subsurface scattering.

5.1. Material and BRDF plugins

• MtlSingleBRDF - The main material type that needs to be connected to Node::material.
• Mtl2Sided - Defines a (possibly different) material for the back side of triangles, as well as the front sides.
• MtlMulti - Use this together with GeomStaticMesh::face_mtlIDs to set different materials for subsets of triangles on one geometric object.
• MtlVRmat - Load a V-Ray shader from a .vrmat (formerly .vismat) file. Also supports loading MtlSingleBRDF materials from vrscene files. This is used for transferring materials between different host applications.
• MtlGLSL - Loads a GLSL shader from file and provides some parameters for it. See this page for details.
• MtlOSL - Loads an OSL shader from file and provides some parameters for it. See this page for details.
• MtlRoundEdges - Smooths sharp edges within a given radius by modifying normals.

Some advanced materials:

• MtlMaterialID - Can be used to define a unique color for a specific base material to be used in compositing from a dedicated render channel.
• MtlOverride - Allows you to override the base material for any of the following: reflections, refractions, GI, shadows, environment.
• MtlRenderStats - Overrides visibility and shadow settings for the object using a base material. This material is not to be used nested in bump, wrapper, two-sided or blend materials.
• MtlWrapper - (really advanced) Can be used to specify additional surface properties per material related to GI, render elements etc.

Below is a list of BRDF plugins for the materials:. The difference between the Blinn, Phong, Ward, Cook-Torrance and GGX models is in how the specular highlight behaves and what parameters you have to control it. The respective BRDF plugins combine a diffuse and a glossy reflection component, while VRayMtl provides more options, like a Fresnel term, refraction, etc.

• BRDFVRayMtl - The one BRDF plugin to rule them all. Combines all of the following except Cook-Torrance. This is the preferred choice for most cases.
• BRDFBlinn - The Blinn BRDF model for glossy highlights. See Wikipedia article and VRayMtl#BRDF.
• BRDFCookTorrance - The Cook-Torrance BRDF model for glossy highlights. See Wikipedia.
• BRDFGGX - The new GGX (microfacet GTR) BRDF model for glossy highlights.
• BRDFPhong - The Phong BRDF model for glossy highlights. See Wikipedia article.
• BRDFWard - The Ward BRDF model for glossy highlights. See Wikipedia.
• BRDFDiffuse - A basic diffuse BRDF.
• BRDFGlass - A basic refractive BRDF.
• BRDFGlassGlossy - An extension of BRDFGlass that enables glossy refraction, meaning that rays with equal incoming angle refract at slightly different angles.
• BRDFLight - Self-illumination BRDF. Consider using LightMesh instead.
• BRDFMirror - A basic specular reflection BRDF.

Some BRDFs simulating specific real world materials:

• BRDFCarPaint - Simulation of metallic paint with base color, random metallic flakes and a coating layer.
• BRDFFlakes - Only the flake part of the car paint BRDF.
• BRDFHair3 - A BRDF optimized for hair. Use with GeomHair.
• BRDFLayered - A weighted combination of any number of BRDF plugins.
• BRDFSSS2 - Subsurface scattering for materials like wax, milk, resin, marble, etc. Use BRDFSkinComplex instead for skin.
• BRDFSSS2Complex - SSS with even more parameters.
• BRDFScanned - This loads a real world material sample scanned to a file by our custom hardware. Email us for details.
• BRDFSkinComplex - A skin-specific SSS plugin.
• BRDFStochasticFlakes - A new plugin for randomly generated tiny sparkly particles. This produces a glittery material like ones found on some clothing and footwear.

And bump maps:

• BRDFBump - Applies a bump map to some base BRDF.
• BRDFMultiBump - Combines up to 4 bump maps.
• BRDFBlinn
• BRDFBump
• BRDFCarPaint
• BRDFCookTorrance
• BRDFDiffuse
• BRDFFlakes
• BRDFGGX
• BRDFGlass
• BRDFGlassGlossy
• BRDFHair3
• BRDFLayered
• BRDFLight
• BRDFMirror
• BRDFMultiBump
• BRDFPhong
• BRDFSSS2
• BRDFSSS2Complex
• BRDFScanned
• BRDFSkinComplex
• BRDFStochasticFlakes
• BRDFVRayMtl
• BRDFWard

5.2. Textures and UVW generators

...