# init(floatLiteral:) Creates an opacity object from a single value. ``` init(floatLiteral value: Float) ``` ## Parameters `value` The opacity value. ## Discussion This initializer creates an object that defines the opacity of an entity using a single value for the entire entity. This value is available to the material’s surface shader function, but RealityKit draws the entity fully opaque unless the surface shader function calls `params.surface().set_opacity()`. The following Metal code demonstrates how to set the entity’s opacity in the material’s surface shader function based on `value:` ```swift // Retrieve the opacity scale from the CustomMaterial. float opacityScale = params.material_constants().opacity_scale(); // Use the opacity scale to set the current pixel's opacity. params.surface().set_opacity(opacityScale); ``` --- 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)