---
title: "init(scale:texture:)"
framework: realitykit
role: symbol
role_heading: Initializer
path: "realitykit/custommaterial/opacity/init(scale:texture:)"
---

# init(scale:texture:)

Creates an object that defines the opacity of an entity using a single value, a UV-mapped image texture, or both.

## Declaration

```swift
init(scale: Float = 1.0, texture: CustomMaterial.Texture? = nil)
```

## Parameters

- `scale`: The opacity value for the entire material.
- `texture`: The opacity values as a UV-mapped image.

## Discussion

Discussion Both scale and texture are 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 emulate the blending logic RealityKit uses to render entities with a PhysicallyBasedMaterial in your custom material’s surface shader function:     // Retrieve the opacity scale and threshold from the CustomMaterial.     float opacityScale = params.material_constants().opacity_scale();     float opacityThreshold = params.material_constants().opacity_threshold();

// Retrieve the entity's texture coordinates.     float2 uv = params.geometry().uv0();

// Entities loaded from USDZ or .reality files use texture coordinates with     // a flipped y-axis. This compensates for that.     uv.y = 1.0 - uv.y;

// Retrieve the opacity texture from the material.     auto tex = params.textures();

// Sample the value from the opacity texture.     half opacity = tex.opacity().sample(textureSampler, uv).r;

if (opacityThreshold > 0.0) {         // If the opacity threshold is greater than 0, use masking behavior         // and set the opacity to either 1.0 or 0.0 depending on the value         // of the opacity threshold.         opacity = (opacity <= opacityThreshold) ? 0.0 : 1.0;     } else {         // If the opacity threshold is 0, then mutiply opacity by scale.         opacity *= opacityScale;     }

// Use the calculated value to set the opacity for rendering.     params.surface().set_opacity(opacity);

## See Also

### Creating an opacity object

- [init(floatLiteral:)](realitykit/custommaterial/opacity/init(floatliteral:).md)
- [init(_:)](realitykit/custommaterial/opacity/init(_:).md)