lightChannelMask property
The light channels this node's meshes occupy, an 8-bit bitmask. A light
reaches them only when its own channel mask intersects this one
(light.channelMask & lightChannelMask != 0), so a light can be aimed at
a subset of the scene without a second scene graph. 0xFF (the default)
takes every channel; 0 takes none and leaves the meshes with only
image-based lighting, which channels never gate. Not inherited by
children; set it on each mesh-bearing node.
A directional light's shadowCasterChannelMask tests against this same
value, so a node can be lit without casting into that light's shadow map
and the other way around.
Implementation
int lightChannelMask = 0xFF;