The semantic for surface normal data.
- iOS 8.0+
- macOS 10.8+
- tvOS 9.0+
- watchOS 3.0+
For a geometry source, this semantic identifies data containing the surface normal vector at each vertex in the geometry. SceneKit uses this information to compute lighting effects on the surface.
For a custom shader program, you use this semantic to bind SceneKit’s vertex normal data to an input attribute of the shader.
Vertex normal data is typically an array of three- or four-component vectors.