avoid NaN in the hole sorting comparator#134
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JS Array#Sort doesn't bomb on NaN, but std::sort does
mourner
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Jul 7, 2026
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The slope tiebreak divides by the edge's dx, so a zero-length edge (coincident points that filterPoints has not yet removed) yields
NaN.In JS-world, Array#sort handles that , but for std::sort a comparator returning inconsistent results is undefined behavior (it must be a strict weak ordering; MSVC debug asserts on it, libc++ can crash).
Compare the slopes by cross-multiplication instead, which is exact for the same reason the division was (both dx are non-negative for leftmost points), and order zero-length edges first so the ordering stays strict.