---
title: "init(texture:)"
framework: realitykit
role: symbol
role_heading: Initializer
path: "realitykit/custommaterial/normal-swift.struct/init(texture:)"
---

# init(texture:)

Create an object from a specified texture.

## Declaration

```swift
init(texture: CustomMaterial.Texture? = nil)
```

## Parameters

- `texture`: The image’s texture.

## Discussion

Discussion This initializer creates an object from a normal map texture. Normal mapping is a real-time rendering technique that captures fine surface details for a model using a texture instead of increasing the number of polygons in the model. It works by storing surface normals, which are vectors perpendicular to the surface of the model, from a much higher-resolution version of the same 3D object. A normal map stores each vector in the image by storing the vectors’ X, Y, and Z values as the R, G, and B components of the corresponding pixel in the UV-mapped image. To render an entity using a normal map, set lightingModel to CustomMaterial.LightingModel.lit or CustomMaterial.LightingModel.clearcoat, and call params.surface().set_normal() from its surface shader. The following Metal code demonstrates how to sample and use a value from the normal map in your surface shader function:     // Retrieve the entity's UV texture coordinates.     float2 uv = params.geometry().uv0();

// Models loaded from USDZ or Reality Composer use UVs that are flipped     // on the y-axis. This compensates for that.     uv.y = 1.0 - uv.y;

// Sample the normal map texture based on the resulting UV coordinates.     auto tex = params.textures();     float3 normal = (float3)tex.normal().sample(textureSampler, uv).rgb;

// Set the sampled value as this pixel's normal.     params.surface().set_normal(normal);

## See Also

### Creating a normal object

- [init(_:)](realitykit/custommaterial/normal-swift.struct/init(_:).md)