order polygons in Multipolygon also when creating final result, for d…

…eterministic output
phanecak-maptiler · Mar 14, 2023 · ef14e59 · ef14e59
1 parent 922f307
commit ef14e59
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Showing 2 changed files with 25 additions and 1 deletion.
diff --git a/planetiler-core/src/main/java/com/onthegomap/planetiler/reader/osm/OsmMultipolygon.java b/planetiler-core/src/main/java/com/onthegomap/planetiler/reader/osm/OsmMultipolygon.java
@@ -182,6 +182,7 @@ private static Geometry doBuild(
         return shells.iterator().next().toPolygon();
       } else {
         Polygon[] finished = shells.stream()
+          .sorted(BY_AREA_DESCENDING)
           .map(Ring::toPolygon)
           .toArray(Polygon[]::new);
         return GeoUtils.JTS_FACTORY.createMultiPolygon(finished);

diff --git a/planetiler-core/src/test/java/com/onthegomap/planetiler/reader/osm/OsmMultipolygonTest.java b/planetiler-core/src/test/java/com/onthegomap/planetiler/reader/osm/OsmMultipolygonTest.java
@@ -35,6 +35,7 @@
 import org.locationtech.jts.geom.Coordinate;
 import org.locationtech.jts.geom.CoordinateXY;
 import org.locationtech.jts.geom.Geometry;
+import org.locationtech.jts.geom.MultiPolygon;
 
 /**
  * This class is ported to Java from https://github.com/omniscale/imposm3/blob/master/geom/multipolygon_test.go
@@ -107,7 +108,7 @@ private Node node(double x, double y) {
     return new Node(id++, x, y);
   }
 
-  private void testBuildMultipolygon(List<List<Node>> ways, Geometry expected) throws GeometryException {
+  private void testBuildMultipolygon(List<List<Node>> ways, Geometry expected, boolean withOrdering) throws GeometryException {
     Map<Long, Coordinate> coords = new HashMap<>();
     List<LongArrayList> rings = new ArrayList<>();
     for (List<Node> way : ways) {
@@ -121,6 +122,13 @@ private void testBuildMultipolygon(List<List<Node>> ways, Geometry expected) thr
     OsmReader.NodeLocationProvider nodeLocs = coords::get;
     Geometry actual = OsmMultipolygon.build(rings, nodeLocs, 0);
     assertSameNormalizedFeature(expected, actual);
+    if (withOrdering) {
+      assertEquals(expected.toString(), actual.toString());
+    }
+  }
+
+  private void testBuildMultipolygon(List<List<Node>> ways, Geometry expected) throws GeometryException {
+    testBuildMultipolygon(ways, expected, false);
   }
 
   @Test
@@ -222,6 +230,21 @@ void testSimplePolygonWithHole() throws GeometryException {
     );
   }
 
+  @Test
+  void testSimplePolygonOrdering() throws GeometryException {
+    testBuildMultipolygon(
+      List.of(
+        rectangleNodes(8, 10),
+        rectangleNodes(0, 7)
+      ),
+      newMultiPolygon(
+        rectangle(0, 7),
+        rectangle(8, 10)
+      ),
+      true
+    );
+  }
+
   @Test
   void testSimplePolygonWithMultipleHoles() throws GeometryException {
     testBuildMultipolygon(