You can’t have a surface extending beyond the visible area, in that last situation, the pixels of the lightmap won’t line up with where the wall is, and so you’ll either have shadow pixels extend inside or lit pixels extend outside.
You can’t have a surface extending beyond the visible area, in that last situation, the pixels of the lightmap won’t line up with where the wall is, and so you’ll either have shadow pixels extend inside or lit pixels extend outside.