This node defines a set of 3D surface normal vectors to be used by vertex-based shape nodes that follow it in the scene graph. This node does not produce a visible result during rendering; it simply replaces
the current normals in the rendering state for subsequent nodes to use. This node contains one multiple-valued field that contains the normal vectors.
Surface normals are needed to compute lighting when
the Phong lighting model is used. Most vertex-based shapes that use normals can compute default normals if none are specified, depending on the current normal binding.