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>
vello_cpu keeps every path's coverage (alpha) values in one buffer until
the scene is rasterized, and a strip packs its index into that buffer in
31 bits; Strip::new asserts it fits. A page that painted one form 2^22
times over (22 nested forms, each drawing the next twice) grew the
buffer past 2^31 values at about 7 GB and panicked, and the page failed.
- vello_common (2): StripStorage::room_for_path{,_within} says whether
one more path's coverage, at most the whole surface counted twice,
still fits below that limit or a smaller one.
- vello_cpu (1): the single-threaded dispatcher leaves out fills,
strokes, fast rectangles and layer clips once there is no room,
records it (RenderContext::coverage_full) and can be kept to fewer
values (set_max_coverage).
- hayro (31): RenderSettings::max_coverage passes that limit down, and
a page whose paths were left out reports
InterpreterWarning::ContentTruncated, which PdfCraft already shows as
content skipped past the page's safety budget.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Pq7HyDBXygTf7jcqdsjcfn
kurbo 0.13.1's stroker can give a cubic that is nearly a line (all control points within a
rounding error of its chord) a NaN join, and vello_common's `flatten::fill` drops any path
containing NaN, so the whole outline vanished. An Illustrator outline ending in
`73.763 -0.536 l 73.764 -0.536 73.764 -0.536 73.764 -0.536 c` did (#4907). kurbo tracks the
bug class in linebender/kurbo#617 and #519; #610 is unreleased.
Vendored vello_common patch (2): when the expanded stroke is not finite, `flatten::stroke`
strokes the path again with every quadratic or cubic whose control points lie within the
tolerance of its chord replaced by a line, one element out per element in. A finite outline
is unchanged, and a path with non-finite input is still dropped. `stroke` and
`StripGenerator::generate_stroked_path` take a `Clone` path; vello_cpu's callers pass
`&BezPath` and a copied slice iterator.
Tests: `flatten::tests::a_tiny_degenerate_cubic_does_not_drop_the_stroke` and the render
crate's `stroke_degenerate_cubic` pixel test fail with the fallback disabled;
`a_finite_outline_is_stroked_as_before` and `a_path_with_nan_is_still_dropped` are guards.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SqmHYx8FiWM5PcsoiErgp9
* M2: clip intersection starts its row walk at the first shared row
clip::intersect in vello_common, the step every clipped path passes
through, began its walk over strip rows at the earlier of the two paths'
first rows. Each path therefore visited every row above it, although rows
where one path has no strips produce no output. Every page is clipped (the
crop box is a clip), so this ran for every stroke of every render: on the
A1 engineering sample it was the hottest function in a full-page render.
Start at the later first row, as vello_common 0.1 does. The strips and the
pixels are unchanged; a test counts the rows the walk visits and fails
without the change.
vello_common 0.0.8 is vendored with that one-line PdfCraft patch (marked
in the source), its unit test, the vendor/README.md row and an
ATTRIBUTION.toml entry for its reference image. Cargo.lock records it as a
path crate.
Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com>
* Refresh catalog hashes after merging main
---------
Co-authored-by: Claude Haiku 5.5 <noreply@anthropic.com>
Co-authored-by: Brandon Thomas <echelon@gmail.com>
bflatastic
KenM76andClaude Opus 5.5
