---
title: scatteringFunction
framework: modelio
role: symbol
role_heading: Instance Property
path: modelio/mdlmaterial/scatteringfunction
---

# scatteringFunction

The collection of material properties that define the material’s response to light.

## Declaration

```swift
var scatteringFunction: MDLScatteringFunction { get }
```

## Discussion

Discussion A MDLScatteringFunction object defines a Bidirectional Reflectance Distribution Function (BRDF), which determines how a material interacts with lighting to produce a surface appearance. Though you can access the individual material properties in a scattering function directly, a scattering function object lets you work with the collection of lighting-related material properties as a single unit. Use the MDLScatteringFunction class itself to describe a classical Lambertian/Blinn-Phong shading model, or the MDLPhysicallyPlausibleScatteringFunction class to describe a shading model based more closely on real-world physics. A scattering function determines lighting-related aspects of a material’s appearance, but not all aspects. For features such as opacity and surface deformation, use the methods listed in Working with individual material properties to access the corresponding material properties.