The semantic for surface tangent vector data.
- iOS 10.0+
- macOS 10.12+
- tvOS 10.0+
- watchOS 3.0+
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.