P2.5.2 N-string node set in jts-curve (OV-P2 / Bar 2)

[grootstebozewolf]

Stacked on cursor/p24-hole-meets-diameter-a09a @ 3d11f8e (draft #20, HOLE-OUTER hole-on-diameter). Do not merge this into #7. This is OV-P2 / Bar 2, not OV-P1. Does not merge #12 / #13 / #15 / #16 / #17 / #18 / #19 / #20 / #7. Does not push to feature/sfa-curve-rgr or master. P2.5.5 is not started.

Sentence

The noder is the named-miss suite, one assembly rule at a time. P2.1–P2.4 landed (pair nodes, overlap-as-edge, bite vs hole, two-hole, hole-on-diameter). Next general-N rung is all-pairs CurveSegmentString nodes in jts-curve. Densify is never a noder. Pick C (CurveSegmentString in jts-curve). A (metadata) already shipped. B (lie that [i,i+1] is non-linear in core SegmentString) is P2.5.5, 74 files, LOCKED — not started.

What this is

P2.5.2: same atoms as P2.1 (CurveSegmentString chord/arc + CurveSegmentNoder), N pairs not 2.

Package-private in org.locationtech.jts.operation.overlayng.curve:

• CurveSegmentNoder.nodes(Geometry[] geoms)
• CurveSegmentNoder.nodes(List<List<CurveSegmentString>> groups, double scale)
• CurveSegmentNoder.nodes(CurveSegmentString[] strings, double scale)

Each unordered pair runs the existing pair noder. The N-set is the unique union. N=2 delegates to the pair path (bit-identical). MIXED / pinch stay edges via the existing P2.2 path — nodes() may still be null on a MIXED pair; all-pairs does not invent crossings there. Geometry-level holed pair stays null (walk uses hole rings as strings, as in P2.3/P2.4).

No faces (P2.5.3). No snap-rounding (P2.5.4). No org.locationtech.jts.noding.SegmentString change (P2.5.5). No new public API. Name is OverlayNGCurve.

Pins

Reuse existing kit-identical pins so N=2 still matches P2.1:

• R1.5 (3.5, ±√12.75)
• R1.6-2 (0, ±5)
• H-SHELL-2 (±3, 4)
• H-FOUR / H-SHELL-N / H-SHELL-N-ODD (tangent is a node)
• MIXED / pinch / holed Geometry pair still null

New N≥3 pins (existing fixtures only):

• HALF_DISC × HALF_HANGING × STADIUM_FOUR: N-set is the union of the three pair sets, no extras.
• MIXED (ON_DIAMETER) or pinch (CIRCLE_INT_TAN) inside an N-set adds no fake crossing. Pinch at (5, 0) is not a node.
• Holed Geometry pair still null at the noder; an N-set that includes a holed operand does not invent hole-ring nodes.

What this is not

• Not P2.5.3 faces
• Not P2.5.4 robustness
• Not P2.5.5 core SegmentString / Noder (74-file blast)
• Not RobustLineIntersector / MonotoneChain / ScaledNoder / HotPixel changes
• Not a merge into feature/sfa-curve-rgr / PR SFA/SQL-MM curve awareness: Curve rename, arc-aware operations, OverlayNGCurve ratchet (#1195 RGR series) #7 / locationtech master
• Not overlay-kit work on CC-NEST-ANNULUS / R1.6-honesty / H-DISC
• Does not rewrite P2.1–P2.4 pair behaviour

Verify

mvn -pl modules/curve -am test -DfailIfNoTests=false -Dcheckstyle.skip=true -Dpmd.skip=true \
  -Dtest=CurveSegmentStringTest,CompoundCurveShellOverlayTest,CircularArcOverlayTest,CircularDiscOverlayTest,CircularDiscPolygonOverlayTest,CircularLineOverlayTest,OverlayNGCurvePhase0Test,OverlayNGCurveRatchetTest,OverlayNGCurvePerfGateTest
bash dev/check-no-curved.sh
mvn -pl modules/curve checkstyle:check
mvn -pl modules/curve pmd:check

All green after this revision:

• CurveSegmentStringTest 20 / 0 (N=2 bit-identical to P2.1 pins; N=3 union of HALF_DISC / HALF_HANGING / STADIUM_FOUR; MIXED / pinch add no fake node; holed Geometry pair stays null)
• CompoundCurveShellOverlayTest 27 / 0 (P2.1–P2.4 / HOLE-OUTER unchanged)
• CircularArcOverlayTest 11 / 0
• CircularDiscOverlayTest 12 / 0
• CircularDiscPolygonOverlayTest 7 / 0
• CircularLineOverlayTest 7 / 0
• OverlayNGCurvePhase0Test 19 / 0
• OverlayNGCurveRatchetTest 50 / 0
• OverlayNGCurvePerfGateTest 82 / 0 (15% slack)
• Naming-guard OK; Checkstyle 0 violations; PMD check on jts-curve succeeded

Slack stays 15%. Overlay name is OverlayNGCurve. No new public API. No noder was written in jts-core. P2.5.5 was not started.