[geos-commits] [SCM] GEOS branch 3.15 updated. 19ff2e15e6be07e853db3c4ec5c3229ed10abf42

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- Log -----------------------------------------------------------------
commit 19ff2e15e6be07e853db3c4ec5c3229ed10abf42
Author: Daniel Baston <dbaston at gmail.com>
Date:   Wed Sep 9 09:39:33 2026 -0400

    NodableArcString: Skip split points having the same angle as an endpoint (#1513)

diff --git a/NEWS.md b/NEWS.md
index 5416e955d..831d214db 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -2,7 +2,7 @@
 2026-xx-xx
 
 - Fixes/Improvements:
-  -
+  - Fix arc noding failure with endpoint intersections (GH-1513, Dan Baston)
 
 ## Changes in 3.15.0
 2026-09-01
diff --git a/src/noding/NodableArcString.cpp b/src/noding/NodableArcString.cpp
index 6db428795..5b41a62f8 100644
--- a/src/noding/NodableArcString.cpp
+++ b/src/noding/NodableArcString.cpp
@@ -151,8 +151,32 @@ prepareArcPoints(const CircularArc& arc, std::vector<CoordinateXYZM> splitPoints
         // Calculate the midpoint of an arc between p0 and p2.
         // We don't actually use the calculated point here, we just want to make sure that
         // the arc from p0 to p2 is long enough to contain a midpoint.
-        const geom::CoordinateXY p1 = algorithm::CircularArcs::getMidpoint(p0, p2, center, arc.getRadius(), true);
+        const double t0 = algorithm::CircularArcs::getAngle(p0, center);
+        const double t2 = algorithm::CircularArcs::getAngle(p2, center);
+        if (t0 == t2) {
+#if DEBUG_NODABLE_ARC_STRING
+            std::cout << "Skipping split point " << p2 << " because the arc endpoints have the same angle" << std::endl;
+#endif
+            if (retained.size() == 1) {
+                splitStart = true;
+            }
+            continue;
+        }
 
+        const double t1 = algorithm::CircularArcs::getMidpointAngle(t0, t2, true);
+
+        // Reject split point where computed angle doesn't fall between endpoints
+        if (!algorithm::Angle::isWithinCCW(t1, t0, t2)) {
+#if DEBUG_NODABLE_ARC_STRING
+            std::cout << "Skipping split point " << p2 << " because the calculated arc midpoint angle " << t1 << " does not fall within the arc from " << t0 << " to " << t2 << std::endl;
+#endif
+            if (retained.size() == 1) {
+                splitStart = true;
+            }
+            continue;
+        }
+
+        const geom::CoordinateXY p1 = algorithm::CircularArcs::createPoint(center, arc.getRadius(), t1);
         if (p1.equals2D(p0) || p1.equals2D(p2)) {
 #if DEBUG_NODABLE_ARC_STRING
             std::cout << "Skipping split point " << p2 << " because the calculated arc midpoint " << p1 << " equals one of the endpoints" << std::endl;
@@ -173,21 +197,6 @@ prepareArcPoints(const CircularArc& arc, std::vector<CoordinateXYZM> splitPoints
             continue;
         }
 
-        // Reject split point where computed doesn't fall between endpoints
-        const double t0 = algorithm::Angle::normalizePositive(isCCW ? arc.theta0() : arc.theta2());
-        const double t1 = algorithm::Angle::normalizePositive(algorithm::CircularArcs::getAngle(p1, center));
-        const double t2 = algorithm::Angle::normalizePositive(isCCW ? arc.theta2() : arc.theta0());
-
-        if (!algorithm::Angle::isWithinCCW(t1, t0, t2)) { // != isCCW) {
-#if DEBUG_NODABLE_ARC_STRING
-            std::cout << "Skipping split point " << p2 << " because the calculated arc midpoint " << p1 << " does not fall within the arc from " << p0 << " to " << p2 << std::endl;
-#endif
-            if (retained.size() == 1) {
-                splitStart = true;
-            }
-            continue;
-        }
-
 #if DEBUG_NODABLE_ARC_STRING
         std::cout << "Keeping split point " << p2 << std::endl;
 #endif
diff --git a/tests/unit/operation/overlayng/OverlayNGTest.cpp b/tests/unit/operation/overlayng/OverlayNGTest.cpp
index 0240fa457..3ee1821c6 100644
--- a/tests/unit/operation/overlayng/OverlayNGTest.cpp
+++ b/tests/unit/operation/overlayng/OverlayNGTest.cpp
@@ -845,4 +845,15 @@ void object::test<64>()
     testOverlay(a, b, exp, OverlayNG::UNION, 0);
 }
 
+template<>
+template<>
+void object::test<65>()
+{
+    set_test_name("Intersection of circular CurvePolygon with itself");
+
+    std::string a = "CURVEPOLYGON (CIRCULARSTRING (-1 0,0 1,1 0,0 -1,-1 0))";
+
+    testOverlay(a, a, a, OverlayNG::INTERSECTION, 0);
+}
+
 } // namespace tut

-----------------------------------------------------------------------

Summary of changes:
 NEWS.md                                          |  2 +-
 src/noding/NodableArcString.cpp                  | 33 +++++++++++++++---------
 tests/unit/operation/overlayng/OverlayNGTest.cpp | 11 ++++++++
 3 files changed, 33 insertions(+), 13 deletions(-)


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