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# MDLMaterialSemantic

Options for the semantic use of a material property’s value in rendering a particular surface appearance; used by the [`semantic`](/documentation/ModelIO/MDLMaterialProperty/semantic) property.

```
enum MDLMaterialSemantic
```

## Topics

### Constants

[`MDLMaterialSemanticBaseColor`](/documentation/ModelIO/MDLMaterialSemantic/baseColor)

The inherent color of a surface, to be used as a modulator during shading.

[`MDLMaterialSemanticSubsurface`](/documentation/ModelIO/MDLMaterialSemantic/subsurface)

The degree to which light scatters under the surface of a material.

[`MDLMaterialSemanticMetallic`](/documentation/ModelIO/MDLMaterialSemantic/metallic)

The degree to which a material appears as a dielectric surface (lower values) or as a metal (higher values).

[`MDLMaterialSemanticSpecular`](/documentation/ModelIO/MDLMaterialSemantic/specular)

The intensity of specular highlights that appear on the material’s surface.

[`MDLMaterialSemanticSpecularExponent`](/documentation/ModelIO/MDLMaterialSemantic/specularExponent)

The exponent to be used in Blinn-Phong approximation of the material’s specular response.

[`MDLMaterialSemanticSpecularTint`](/documentation/ModelIO/MDLMaterialSemantic/specularTint)

The balance of color for specular highlights, between the light color (lower values) and the material’s base color (at higher values).

[`MDLMaterialSemanticRoughness`](/documentation/ModelIO/MDLMaterialSemantic/roughness)

The degree to which a material appears smooth, affecting both diffuse and specular response.

[`MDLMaterialSemanticAnisotropic`](/documentation/ModelIO/MDLMaterialSemantic/anisotropic)

The degree to which specular highlights elongate in the direction of the local tangent basis.

[`MDLMaterialSemanticAnisotropicRotation`](/documentation/ModelIO/MDLMaterialSemantic/anisotropicRotation)

The angle at which anisotropic effects are rotated relative to the local tangent basis.

[`MDLMaterialSemanticSheen`](/documentation/ModelIO/MDLMaterialSemantic/sheen)

The intensity of highlights that appear only at glancing angles on a material’s surface.

[`MDLMaterialSemanticSheenTint`](/documentation/ModelIO/MDLMaterialSemantic/sheenTint)

The balance of color for highlights that appear only at glancing angles, between the light color (lower values) and the material’s base color (at higher values).

[`MDLMaterialSemanticClearcoat`](/documentation/ModelIO/MDLMaterialSemantic/clearcoat)

The intensity of a second specular highlight, similar to the gloss that results from a clear coat on an automotive finish.

[`MDLMaterialSemanticClearcoatGloss`](/documentation/ModelIO/MDLMaterialSemantic/clearcoatGloss)

The spread of a second specular highlight, similar to the gloss that results from a clear coat on an automotive finish.

[`MDLMaterialSemanticEmission`](/documentation/ModelIO/MDLMaterialSemantic/emission)

The color emitted as radiance from a material’s surface.

[`MDLMaterialSemanticBump`](/documentation/ModelIO/MDLMaterialSemantic/bump)

The degree of perturbation in a material’s surface.

[`MDLMaterialSemanticOpacity`](/documentation/ModelIO/MDLMaterialSemantic/opacity)

The opacity of a material’s surface.

[`MDLMaterialSemanticInterfaceIndexOfRefraction`](/documentation/ModelIO/MDLMaterialSemantic/interfaceIndexOfRefraction)

The index of refraction for the medium surrounding a material.

[`MDLMaterialSemanticMaterialIndexOfRefraction`](/documentation/ModelIO/MDLMaterialSemantic/materialIndexOfRefraction)

The index of refraction for a material itself.

[`MDLMaterialSemanticObjectSpaceNormal`](/documentation/ModelIO/MDLMaterialSemantic/objectSpaceNormal)

The variation in the surface normal vectors in a material, relative to model coordinate space.

[`MDLMaterialSemanticTangentSpaceNormal`](/documentation/ModelIO/MDLMaterialSemantic/tangentSpaceNormal)

The variation in the surface normal vectors in a material, relative to surface tangent coordinate space.

[`MDLMaterialSemanticDisplacement`](/documentation/ModelIO/MDLMaterialSemantic/displacement)

The displacement of a material’s surface relative to the surface normal.

[`MDLMaterialSemanticDisplacementScale`](/documentation/ModelIO/MDLMaterialSemantic/displacementScale)

The scaling factor for displacement of a material’s surface.

[`MDLMaterialSemanticAmbientOcclusion`](/documentation/ModelIO/MDLMaterialSemantic/ambientOcclusion)

The attenuation of ambient light due to local geometry variations on a surface.

[`MDLMaterialSemanticAmbientOcclusionScale`](/documentation/ModelIO/MDLMaterialSemantic/ambientOcclusionScale)

The scaling factor for ambient occlusion shading.

[`MDLMaterialSemanticNone`](/documentation/ModelIO/MDLMaterialSemantic/none)

The material property’s [`semantic`](/documentation/ModelIO/MDLMaterialProperty/semantic) property has not been initialized.

[`MDLMaterialSemanticUserDefined`](/documentation/ModelIO/MDLMaterialSemantic/userDefined)

The meaning of the material property’s value is not one of the standard semantic uses recognized by Model I/O.

## Relationships

### Conforms To

[`SendableMetatype`](/documentation/Swift/SendableMetatype)

[`Sendable`](/documentation/Swift/Sendable)

[`BitwiseCopyable`](/documentation/Swift/BitwiseCopyable)

[`Hashable`](/documentation/Swift/Hashable)

[`RawRepresentable`](/documentation/Swift/RawRepresentable)

[`Equatable`](/documentation/Swift/Equatable)

---

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