Port lucene tessellator fix github-12352 to Elasticsearch 7.17 (#96721)

Author: iverase

docs/changelog/96721.yaml

@@ -0,0 +1,5 @@
+pr: 96721
+summary: Port lucene tessellator fix github-12352 to Elasticsearch 7.17
+area: Geo
+type: bug
+issues: []

server/src/main/java/org/apache/lucene/geo/XTessellator.java

@@ -814,23 +814,26 @@ private static Node splitPolygon(final Node a, final Node b, boolean edgeFromPol
      * Determines whether a diagonal between two polygon nodes lies within a polygon interior. (This determines the validity of the ray.)
      **/
     private static boolean isValidDiagonal(final Node a, final Node b) {
+        if (a.next.idx == b.idx || a.previous.idx == b.idx
+        // check next edges are locally visible
+            || isLocallyInside(a.previous, b) == false
+            || isLocallyInside(b.next, a) == false
+            // check polygons are CCW in both sides
+            || isCWPolygon(a, b) == false
+            || isCWPolygon(b, a) == false) {
+            return false;
+        }
         if (isVertexEquals(a, b)) {
-            // If points are equal then use it if they are valid polygons
-            return isCWPolygon(a, b);
+            return true;
         }
-        return a.next.idx != b.idx
-            && a.previous.idx != b.idx
-            && isIntersectingPolygon(a, a.getX(), a.getY(), b.getX(), b.getY()) == false
-            && isLocallyInside(a, b)
-            && isLocallyInside(b, a)
-            && isLocallyInside(a.previous, b)
-            && isLocallyInside(b.next, a)
-            && middleInsert(a, a.getX(), a.getY(), b.getX(), b.getY())
-            // make sure we don't introduce collinear lines
+        return isLocallyInside(a, b) && isLocallyInside(b, a) && middleInsert(a, a.getX(), a.getY(), b.getX(), b.getY())
+        // make sure we don't introduce collinear lines
             && area(a.previous.getX(), a.previous.getY(), a.getX(), a.getY(), b.getX(), b.getY()) != 0
             && area(a.getX(), a.getY(), b.getX(), b.getY(), b.next.getX(), b.next.getY()) != 0
             && area(a.next.getX(), a.next.getY(), a.getX(), a.getY(), b.getX(), b.getY()) != 0
-            && area(a.getX(), a.getY(), b.getX(), b.getY(), b.previous.getX(), b.previous.getY()) != 0;
+            && area(a.getX(), a.getY(), b.getX(), b.getY(), b.previous.getX(), b.previous.getY()) != 0
+            // this call is expensive so do it last
+            && isIntersectingPolygon(a, a.getX(), a.getY(), b.getX(), b.getY()) == false;
     }
 
     /** Determine whether the polygon defined between node start and node end is CW */

server/src/test/java/org/apache/lucene/geo/XTessellatorTests.java

@@ -1090,6 +1090,26 @@ public void testComplexPolygon54() throws Exception {
         }
     }
 
+    public void testComplexPolygon55() throws Exception {
+        String geoJson = GeoTestUtil.readShape("github-12352-1.geojson.gz");
+        Polygon[] polygons = Polygon.fromGeoJSON(geoJson);
+        for (Polygon polygon : polygons) {
+            List<XTessellator.Triangle> tessellation = XTessellator.tessellate(polygon);
+            assertEquals(area(polygon), area(tessellation), 0.0);
+            // don't check edges as it takes several minutes
+        }
+    }
+
+    public void testComplexPolygon56() throws Exception {
+        String geoJson = GeoTestUtil.readShape("github-12352-2.geojson.gz");
+        Polygon[] polygons = Polygon.fromGeoJSON(geoJson);
+        for (Polygon polygon : polygons) {
+            List<XTessellator.Triangle> tessellation = XTessellator.tessellate(polygon);
+            assertEquals(area(polygon), area(tessellation), 0.0);
+            // don't check edges as it takes several minutes
+        }
+    }
+
     private void checkPolygon(String wkt) throws Exception {
         Polygon polygon = (Polygon) SimpleWKTShapeParser.parse(wkt);
         List<XTessellator.Triangle> tessellation = XTessellator.tessellate(polygon);