After 1b, triangulating both polygons on every pair was the largest
remaining overlap cost (27% of main-thread samples on the corpus job).
PartOverlapChecker now triangulates each part at most once per check,
lazily after the bounding-box gate, and passes the triangles to a new
internal Collision.HasOverlap overload that runs the unchanged
OverlapRegions body. Triangles are only read by clipping and hole
subtraction, so reuse gives identical verdicts.
Verification:
- 49,000 seeded decisions with reused triangles match LegacyCollision;
triangles stay bit-identical to a fresh triangulation afterwards.
- Debug PolygonTriangulations: 246 -> 40 and 64 -> 36 per grid check;
sharing triangles per Program instead fails 23 tests.
- Corpus job (169 parts, --engines Default --parallel 1): median
13,398 -> 12,702 ms over 4+4 alternating runs vs 1b, identical
outcomes; serialized layout byte-identical to the base.
Also records the Follow-up B' (Slices 1a, 1b, 2a) measurements in
docs/performance/fill-performance.md.
Collision.HasOverlap only needs the verdict, but it went through Check,
which also collected crossing points. Triangulation, clipping and hole
subtraction now live in one private OverlapRegions method shared by Check
and HasOverlap, so verdict arithmetic stays single-sourced; Check output is
unchanged.
Tests: a frozen copy of the previous Collision is the oracle. 50,000 seeded
HasOverlap verdicts and 2,400 bitwise Check results match it, plus
containment, contact, hole and input-immutability cases. A Debug-only
PerfCounters.CrossingPointScans counter proves HasOverlap no longer scans.
Malformed polygons with null outer vertices still throw when the bounding
boxes overlap (now ArgumentNullException from triangulation rather than
NullReferenceException from ToLines).
Measured (Release, same harness in both trees): about 44% less time per
overlap-only polygon check, allocations 10.0 -> 7.9 MB per 155-pair sweep.
The 169-part serialized corpus layout is byte-identical.
Replace the Terra scaffold with an independent configuration-space contact placer and bounded stock-plan search. Include plugin tests, synthetic and DXF benchmark drivers, results, and deployment documentation.
Correct shared collision clipping and hole subtraction so curved-hole inserts validate consistently. Cover translated layouts, spacing violations, operand order, winding, and independent boolean-area comparisons.
Validation: 1,293 tests passed with 12 fixture skips; all 34 synthetic/generated and four DXF cases are valid and complete.
Collision stays hand-rolled because it is the reference for a future GPU
kernel, but its inputs now come from Clipper region offsets. Pin down that
lines-only, round-join, 1e-4-precision polygons keep the contact and
part-in-part semantics: a neighbor inside a collapsed slot, a part inside
a hole that shrank by the spacing, and zero-spacing edge contact.
Document which steps are per-polygon preparation to cache and upload once,
and which are per-pair kernel-shaped work.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Repo-wide sweep with the pinned CSharpier 1.3.0 tool. Whitespace and
line-wrapping only; OpenNest.Engine.Tests (109) and OpenNest.IO.Tests
pass after reformat, full solution builds 0 errors.
Added .csharpierignore so csproj/config XML keeps its existing layout
(CSharpier's XML wrapping churns attributes with zero benefit).
Formatting is now enforceable: dotnet csharpier check . passes.
The witness-probe overlap test missed small corner intersections: its
candidate points (crossing-edge midpoints and vertex-centroid midpoints)
can all land on a part boundary or outside the intersection, so two 10x10
parts at (0,0) and (9,9) with zero spacing were accepted despite sharing
a 1x1 unit of material.
Route the overlap decision through Collision, which clips triangulated
polygons and keeps only positive-area regions, catching corner overlaps,
containment, and coincident poses while legal edge/corner contact stays
legal. Collision's hole subtraction was conservative (partially-clipped
triangles were kept whole), so a part inside another part's cutout could
false-positive depending on triangulation alignment; subtract holes
exactly instead: a piece outside a convex hole triangle is the union of
its clips against each edge's outside half-space.
Polygon-polygon collision detection using convex decomposition (ear-clipping
triangulation) followed by Sutherland-Hodgman clipping on each triangle pair.
Handles overlapping, non-overlapping, edge-touching, containment, and concave
polygons. Includes hole subtraction support for future use.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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