Probably not. To be clear: most built-in instruments _already_ do the ‘right equation’ for lighting, and contain an opaque backing, so no mod is needed.

Sounds Great! Will the X-Plane Library for instrumentation with such lighting be updated to provide this function and placed in a forthcoming release? I hope so…

Exactly. The additive must happen BEFORE transparency compositing or you won’t get the right math.

Understood, if that means no transparent background to an additive or back-lit generic annunciator. I think I do have an issue that this might cure.

Maybe.
1. The background can be opaque or transparent, depending on what the annunciator is sitting ON TOP OF. But the background to the annunciator should come from the instrument background or panel background, NOT some other piece of OBJ.
2. The left side of gen_ann_something-1.png should only be transparent if the annunciator has NO foreground image when off. That depends on the type of annunciator. For annunciators marked ‘glass’ (representing a digital display on a screen) a transparent left side for the -1 layer makes sense. For a mechanical annunciator, well, it depends on the mechanism.

EDIT: let me make this simpler. I am only saying one thing:
IF you are going to have additive lighting on an instrument (via either a LIT-1 layer for additive or back-lit type lighting or via a -1 layer for a glass-type lighting)
THEN: the sum of the panel background and instrument background should NOT contain transparency.

The reason for this is that additive lighting in the panel only works when there is somethign opaque to add over. You can’t do additive lighting between different triangles in an OBJ.

Yes!!!

ac3d has strict rules about when it ‘recognizes’ panel texture. Unfortunately I am flat on my back for time and am therefore not helping third party authors with individual projects right now. 🙁 🙁 So if you can find another ac3d user they can probably find the issue. The rules are documented in the README/manual but they are also quite confusing.