# DiffuseProbeResource A resource containing baked diffuse lighting data organized as a tetrahedral probe mesh. ``` final class DiffuseProbeResource ``` ## 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 [`convenience init(positions: [SIMD3], coefficients: [InlineArray<3, SIMD4>], tetrahedronIndices: [SIMD4]) throws`](/documentation/RealityKit/DiffuseProbeResource/init(positions:coefficients:tetrahedronIndices:)) Creates a diffuse probe resource from arrays of probe data. ## See Also [`struct DiffuseLightProbeGroupComponent`](/documentation/RealityKit/DiffuseLightProbeGroupComponent) A component that stores diffuse probe data for a spatial region. [`struct DiffuseLightProbeReceiverComponent`](/documentation/RealityKit/DiffuseLightProbeReceiverComponent) A component that receives diffuse lighting from a referenced probe group. ## Relationships ### Conforms To [`Sendable`](/documentation/Swift/Sendable) [`SendableMetatype`](/documentation/Swift/SendableMetatype) [`Resource`](/documentation/RealityKit/Resource) --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)