---
title: materialIndexOfRefraction
framework: modelio
role: symbol
role_heading: Instance Property
path: modelio/mdlscatteringfunction/materialindexofrefraction
---

# materialIndexOfRefraction

The index of refraction for the medium surrounding a material.

## Declaration

```swift
var materialIndexOfRefraction: MDLMaterialProperty { get }
```

## Discussion

Discussion This value corresponds to the n1 parameter in Schlick’s equation for approximating Fresnel reflection effects. Typically, one assumes a the medium surrounding a material is air or empty space, so the default value of 1.0 suffices for most uses of this semantic.

## See Also

### Working with Shading Properties

- [baseColor](modelio/mdlscatteringfunction/basecolor.md)
- [emission](modelio/mdlscatteringfunction/emission.md)
- [specular](modelio/mdlscatteringfunction/specular.md)
- [interfaceIndexOfRefraction](modelio/mdlscatteringfunction/interfaceindexofrefraction.md)
- [normal](modelio/mdlscatteringfunction/normal.md)
- [ambientOcclusion](modelio/mdlscatteringfunction/ambientocclusion.md)
- [ambientOcclusionScale](modelio/mdlscatteringfunction/ambientocclusionscale.md)