Sort bone weights descending before Resize(4) truncation#22
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ousnius merged 2 commits intoousnius:mainfrom Apr 25, 2026
Merged
Sort bone weights descending before Resize(4) truncation#22ousnius merged 2 commits intoousnius:mainfrom
ousnius merged 2 commits intoousnius:mainfrom
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Sort order was ascending (`lhs.Weight.CompareTo(rhs.Weight)`), so when the subsequent `Resize(4)` limited each vertex to at most four influences, it discarded the LARGEST weights and kept the smallest. Skinning of vertices with more than four bone influences produced visibly broken deformation after this code path ran. Matches C++ nifly NifFile.hpp:50 `BoneWeightsSort` operator which returns `rhs.weight < lhs.weight` (descending).
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UpdateSkinPartitionssorts per-vertex bone weights withlhs.CompareTo(rhs)(ascending) and then callsResize(4), which discards the heaviest weights instead of the lightest. Vertices with more than 4 influences end up keeping their weakest bones.C++ reference:
nifly/include/NifFile.hpp:50—BoneWeightsSort::operator()returnsrhs.weight < lhs.weight, i.e. descending.Fix: change the comparator to
rhs.CompareTo(lhs).Maps to issue #15 item B5.