Since I now have a GUI, I made it show me a ton more information about what the light mapper is doing, and finally pinned down a bug that was really causing problems and had caused me to give up on normal maps. I can now click on a wall or plane, and have the lighting window show me exactly what the light mapper sees. This helped me figure out why normal mapping so so damned hard: the stupid light angle calculations were all wrong. They just happened to work in the sectors that I tested manually.
By highlighting the wall (in red) and pressing “Show Single Surface Bake” the lighting engine gives me a bipmap of exactly what it sees. It also shows me across the top of it exactly what it used when figuring out which vertical slice was the brightest light source, and along the right it shows me the brightness data for that column as well. The red crosshair tells me exactly where it thinks the light is, and now I have a correct direction to apply lighting from. Along the rest of the border is the final light color that will be applied to this wall. Greenish, it looks like it's combining the blue floor and the yellow overhang in front of it.
