The branch used TriangleSelector::remap_painting(), which pairs a source
paint triangle with a target triangle overlapping it to within
TriangleCursor::tolerance. That is right after a remesh, which leaves the
surface where it was, and wrong after a bake, which has moved it by the
relief depth - most of the paint finds no partner. transfer_facet_paint()
asks the other question: every triangle of the new mesh takes the state
painted at its foot point on the old one, which is exactly where it came
from however deep the relief.
It also does all four paint channels rather than colour alone, and it runs
where the volume is read, so the snapshot and the timestamp that guarded
against the user painting while the bake ran are no longer needed: the
annotation is read at commit time and is by definition current.
The function and its call site are byte for byte what the model-UV branch
carries, so the two merge in any order and in either order produce one
mechanism rather than two fighting over mmu_segmentation_facets. The
regression test is unchanged except for the call it makes.
ExPikaPaka
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