Fix algorithm that chooses the bridge between a polygon and a hole (#11988)

lucene/CHANGES.txt

@@ -183,6 +183,9 @@ Bug Fixes
   so that subsequent passage merges don't mean that we return too few passages in
   total. (Alan Woodward, Dawid Weiss)
 
+* GITHUB#11986: Fix algorithm that chooses the bridge between a polygon and a hole when there is
+  common vertex. (Ignacio Vera)
+
 Optimizations
 ---------------------
 * GITHUB#11738: Optimize MultiTermQueryConstantScoreWrapper when a term is present that matches all

lucene/core/src/java/org/apache/lucene/geo/Tessellator.java

@@ -435,42 +435,21 @@ public final class Tessellator {
     final double my = connection.getY();
     double tanMin = Double.POSITIVE_INFINITY;
     double tan;
-    p = connection.next;
-    {
-      while (p != stop) {
+    p = connection;
+    do {
       if (hx >= p.getX()
           && p.getX() >= mx
           && hx != p.getX()
-            && pointInEar(
-                p.getX(), p.getY(), hy < my ? hx : qx, hy, mx, my, hy < my ? qx : hx, hy)) {
+          && pointInEar(p.getX(), p.getY(), hy < my ? hx : qx, hy, mx, my, hy < my ? qx : hx, hy)) {
         tan = Math.abs(hy - p.getY()) / (hx - p.getX()); // tangential
-          if (isVertexEquals(p, connection) && isLocallyInside(p, holeNode)) {
-            // make sure we are not crossing the polygon. This might happen when several holes have
-            // a bridge to the same polygon vertex
-            // and this vertex has different vertex.
-            boolean crosses =
-                GeoUtils.lineCrossesLine(
-                    p.getX(),
-                    p.getY(),
-                    holeNode.getX(),
-                    holeNode.getY(),
-                    connection.next.getX(),
-                    connection.next.getY(),
-                    connection.previous.getX(),
-                    connection.previous.getY());
-            if (crosses == false) {
-              connection = p;
-              tanMin = tan;
-            }
-          } else if ((tan < tanMin || (tan == tanMin && p.getX() > connection.getX()))
+        if ((tan < tanMin || (tan == tanMin && p.getX() > connection.getX()))
             && isLocallyInside(p, holeNode)) {
           connection = p;
           tanMin = tan;
         }
       }
       p = p.next;
-      }
-    }
+    } while (p != stop);
     return connection;
   }
 

lucene/core/src/test/org/apache/lucene/geo/TestTessellator.java

@@ -845,7 +845,7 @@ public class TestTessellator extends LuceneTestCase {
     Polygon polygon = polygons[0];
     TestCountingMonitor monitor = new TestCountingMonitor();
     Tessellator.tessellate(polygon, true, monitor);
-    assertThat("Expected many monitor calls", monitor.count, greaterThan(400));
+    assertThat("Expected many monitor calls", monitor.count, greaterThan(390));
     assertThat("Expected specific number of splits", monitor.splitsStarted, equalTo(3));
     assertThat(
         "Expected splits to start and end", monitor.splitsStarted, equalTo(monitor.splitsEnded));
@@ -891,6 +891,30 @@ public class TestTessellator extends LuceneTestCase {
         ex.getMessage());
   }
 
+  public void testComplexPolygon53() throws Exception {
+    String geoJson = GeoTestUtil.readShape("github-11986-1.geojson.gz");
+    Polygon[] polygons = Polygon.fromGeoJSON(geoJson);
+    for (Polygon polygon : polygons) {
+      List<Tessellator.Triangle> tessellation = Tessellator.tessellate(polygon, true);
+      assertEquals(area(polygon), area(tessellation), 0.0);
+      for (Tessellator.Triangle t : tessellation) {
+        checkTriangleEdgesFromPolygon(polygon, t);
+      }
+    }
+  }
+
+  public void testComplexPolygon54() throws Exception {
+    String geoJson = GeoTestUtil.readShape("github-11986-2.geojson.gz");
+    Polygon[] polygons = Polygon.fromGeoJSON(geoJson);
+    for (Polygon polygon : polygons) {
+      List<Tessellator.Triangle> tessellation = Tessellator.tessellate(polygon, true);
+      assertEquals(area(polygon), area(tessellation), 0.0);
+      for (Tessellator.Triangle t : tessellation) {
+        checkTriangleEdgesFromPolygon(polygon, t);
+      }
+    }
+  }
+
   private static class TestCountingMonitor implements Tessellator.Monitor {
     private int count = 0;
     private int splitsStarted = 0;