A light source that can be attached to a node to illuminate the scene.
- iOS 8.0+
- macOS 10.8+
- tvOS 9.0+
- watchOS 2.0+
You set a light’s type using its
type property. Depending on a light’s type, its position and direction may affect its behavior—you control the light’s position and direction through the node that the light is attached to. The direction of a light, if applicable to its type, is along the negative z-axis of its node’s local coordinate system.
A light’s other properties affect how it illuminates a scene. All lights have a
color property, which interacts with
SCNMaterial objects to produce the pixel colors in a rendered scene. Other properties, such as attenuation, shadowing, and spot angle, can affect the behavior of certain types of lights.
The number and type of lights in a scene is a key factor in SceneKit’s rendering performance. For efficient rendering, follow these tips:
Use SceneKit lights only for dynamic light sources or lights that affect moving objects. For statically lit portions of your scene, create a light map texture in an external 3D authoring tool (also known as baked lighting) and apply it to objects in the scene using the
Minimize the number of lights on each element of the scene. You can achieve most common lighting effects using no more than three lights, and you only need a single ambient light source. SceneKit only uses up to eight light sources per node when rendering, ignoring any additional lights. If you set the
attenuationproperty on a spotlight or omnidirectional light to limit its area of effect, SceneKit ignores the light (and its performance cost) when rendering objects outside that area. You can also use the
categoryproperty to choose which nodes are illuminated by a light.