# init(_:) Creates an object from a physically based material’s ambient occlusion property. ``` init(_ value: PhysicallyBasedMaterial.AmbientOcclusion) ``` ## Parameters `value` The ambient occlusion property from a [`PhysicallyBasedMaterial`](/documentation/RealityKit/PhysicallyBasedMaterial). ## Discussion Ambient occlusion represents the entity’s exposure to ambient light. This initializer creates a new object by copying the values from an existing [`PhysicallyBasedMaterial`](/documentation/RealityKit/PhysicallyBasedMaterial) instance’s [`ambientOcclusion`](/documentation/RealityKit/PhysicallyBasedMaterial/ambientOcclusion-swift.property) property. Specify ambient occlusion by using a UV-mapped image called an *ambient occlusion map*. A value of black (`0.0`) represents parts of the model that receive less ambient light because of a crevice, dent, recessed area, or another part of the same entity blocking ambient light from reaching it. Ambient occlusion values of white (`1.0`) represent flat portions of the model that receive full ambient light. You generate ambient occlusion maps by using a 3D software package. The ambient occlusion texture is available in the material’s surface shader, but RealityKit doesn’t render ambient occlusion unless the surface shader calls `params.surface().set_ambient_occlusion()`. The following Metal code shows how to use the ambient occlusion texture in a surface shader function: ```swift // Retrieve the entity's texture coordinates. float2 uv = params.geometry().uv0(); // Entities loaded from USDZ or .reality files have texture coordinates // with a flipped y-axis. This adjusts for that. uv.y = 1.0 - uv.y; // Sample the ambient occlusion texture and use it to set the // ambient occlusion value to use during rendering. auto tex = params.textures(); half metallic = tex.ambient_occlusion().sample(textureSampler, uv).r; params.surface().set_ambient_occlusion(metallic); ``` --- 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)