3 people c02341f6c0 M2: a wide stroke of a path with y curves is drawn, not dropped (vello_common patch 4) (#6526) ...

A cubic whose second control point is its end point (as the `y` operator builds,
ISO 32000-2 8.5.2.1 Table 58) has a zero derivative at its end. kurbo 0.13.1's
offset curve looks for cusps with a root search on the curvature, which grows
without bound towards that end; at some widths the search stops on the end point
and normalising the zero tangent there gives NaN. vello_common's fill drops any
outline with NaN, so the whole stroke vanished (a two-curve `y` path drew nothing
at 16, 32 and 63 pt; a PDFBox tracker file lost its 32 pt "XX" outline).

The NaN fallback that #4913 added to `flatten::stroke` now also moves such a
control point the stroke tolerance towards the previous control point before
stroking again (the curve moves by at most 4/9 of the tolerance). Outlines that
come back finite take the old path unchanged. The vendor ledger row also gets
back #4913's entry, which a merge had dropped.


Claude-Session: https://claude.ai/code/session_01Pq7HyCHD1R3rywQBPCHXZA

Co-authored-by: mtlcl410 <chuanlin@niar.org.tw>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

2026-11-09 08:31:00 +08:00

..

it

M2: a wide stroke of a path with y curves is drawn, not dropped (vello_common patch 4) (#6526)

2026-11-09 08:31:00 +08:00