---
title: DiffuseProbeResource
framework: realitykit
role: symbol
role_heading: Class
path: realitykit/diffuseproberesource
---

# DiffuseProbeResource

A resource containing baked diffuse lighting data organized as a tetrahedral probe mesh.

## Declaration

```swift
class DiffuseProbeResource
```

## Overview

Overview Diffuse probe resources store spherical harmonic coefficients at discrete 3D positions, connected via a tetrahedral mesh for efficient runtime interpolation. This compact representation enables high probe density throughout a scene, allowing dynamic objects to receive accurate diffuse lighting as they move through different lighting conditions. Probe Data Format Each probe stores first-order (L0 + L1) spherical harmonics: 4 coefficients per RGB channel, for a total of 12 floats (48 bytes) per probe. The tetrahedral mesh adds minimal per-tetrahedron overhead. This compact representation enables high probe density within typical memory budgets.

## Topics

### Initializers

- [init(positions:coefficients:tetrahedronIndices:)](realitykit/diffuseproberesource/init(positions:coefficients:tetrahedronindices:).md)

## Relationships

### Conforms To

- [Resource](realitykit/resource.md)
- [Sendable](swift/sendable.md)
- [SendableMetatype](swift/sendablemetatype.md)

## See Also

### Related Documentation

- [DiffuseLightProbeGroupComponent](realitykit/diffuselightprobegroupcomponent.md)
- [DiffuseLightProbeReceiverComponent](realitykit/diffuselightprobereceivercomponent.md)

### Lightmaps and light probes

- [LightmapResource](realitykit/lightmapresource.md)
- [LightmapComponent](realitykit/lightmapcomponent.md)
- [DiffuseLightProbeGroupComponent](realitykit/diffuselightprobegroupcomponent.md)
- [DiffuseLightProbeReceiverComponent](realitykit/diffuselightprobereceivercomponent.md)