This could be useful :
- when you want to apply an emissive texture to the object during night time for example
- when you want to have a night sensor easily, without perf cost
This would be fired when light is spawned at day time and have day time enabled,
or this would fire when light activated when it's going night, and when the day coming and the light deactivates.
This event callback can return boolean, so if the return is true it's actually enabling/disabling the light.