categoryBitMask

You can assign each node in a scene to one or more categories, where each category corresponds to a bit in the bit mask. You define the mask values used in your app. When SceneKit renders a scene, it compares the each node’s categoryBitMask property with the category bit masks of every other object that participates in the rendering process—lights, cameras, and techniques—using a bitwise AND operation. If the result is a nonzero value, SceneKit includes the node when rendering. The default category bit mask is 1.

Use a node’s category bit mask together with:

• An SCNLight object’s categoryBitMask property to exclude the node from that light’s illumination

• An SCNCamera object’s categoryBitMask property to make the node invisible to that camera

• The category bit masks in an SCNTechnique object’s definition dictionary to include or exclude the node from phases of a multipass rendering technique