<!--
{
  "availability" : [
    "iOS: 8.0.0 - 26.0.0",
    "iPadOS: 8.0.0 - 26.0.0",
    "macCatalyst: 13.1.0 - 26.0.0",
    "macOS: 10.8.0 - 26.0.0",
    "tvOS: 9.0.0 - 26.0.0",
    "visionOS: 1.0.0 - 26.0.0",
    "watchOS: 3.0.0 - 26.0.0"
  ],
  "documentType" : "symbol",
  "framework" : "SceneKit",
  "identifier" : "/documentation/SceneKit/SCNGeometrySource/Semantic-swift.struct/tangent",
  "metadataVersion" : "0.1.0",
  "role" : "Type Property",
  "symbol" : {
    "kind" : "Type Property",
    "modules" : [
      "SceneKit"
    ],
    "preciseIdentifier" : "c:@SCNGeometrySourceSemanticTangent"
  },
  "title" : "tangent"
}
-->

# tangent

The semantic for surface tangent vector data.

```
static let tangent: SCNGeometrySource.Semantic
```

## Discussion

For a geometry source, this semantic identifies data containing the surface tangent vector at each vertex in the geometry. SceneKit uses this information to compute advanced lighting effects on the surface.

For a custom shader program, you use this semantic to bind SceneKit’s vertex tangent data to an input attribute of the shader.

Vertex tangent data is typically an array of three- or four-component vectors.

---

Copyright &copy; 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)