I’m way behind on documentation, and there isn’t any documentation for this yet, but to clarify:
In the named lights list, spill (casting light on the ground and other stuff in HDR mode) and billboards (a square that faces the camera with a picture of the light from a light bulb) are always separate!
Typically the spill light has the same name as the billboard with an _sp suffix, or the billboard has _bb.
Why did we do it this way?
The lights are kept separate because:
- We do not have enough information from the billboards to know how to make a spill. For example, you have a v9 parameterized landing light billboard on your aircraft OBJ. How big (in meters) should the spill be? We don’t know! The billboard params never included enough information to know things like the size and cone ark for a spill light.
- There may not even be a 1:1 correspondence of spill to billboards. For example, any time there is a multi-lightbulb enclosure, it can be a win to use more billboards than spills; overlapping spills hurt fill rate.
Spills are therefore “opt-in” at the named light level; you opt in by adding a _sp variant.
Note that if you use Plane-Maker’s light level, you get spill for free; that interface is a higher level, simpler “I want this thing” type of interface. It only knows about the basic airplane light types, but it is fairly powerful. For example, you can create multiple landing lights (controlled by multiple switches), and you can use the “generic” lights for utility purposes, like inlet ice lights, leading edge lights, logo lights, etc.