channelMask property
The light channels this light illuminates, an 8-bit mask (default
0xFF, every channel). A node receives this light only when
channelMask & node.lightChannelMask is nonzero, so a zero mask on
either side never intersects and the light is skipped. Channels do not
affect image-based (environment) lighting, which every node receives.
Deliberately independent of shadowCasterChannelMask, which selects what renders into the shadow map. A node can be lit without casting, or cast without being lit.
Implementation
int channelMask;