From 3bbfb48481c212d8166b559e5f94d6e49440c1ce Mon Sep 17 00:00:00 2001
From: Mike Barry <msb5014@gmail.com>
Date: Sat, 23 Sep 2023 06:08:49 -0400
Subject: [PATCH] comments

---
 .../onthegomap/planetiler/FeatureMerge.java   | 29 +++++++++++--------
 .../planetiler/FeatureMergeTest.java          | 19 ------------
 2 files changed, 17 insertions(+), 31 deletions(-)

diff --git a/planetiler-core/src/main/java/com/onthegomap/planetiler/FeatureMerge.java b/planetiler-core/src/main/java/com/onthegomap/planetiler/FeatureMerge.java
index aa2bf20e52..41fc61f0b7 100644
--- a/planetiler-core/src/main/java/com/onthegomap/planetiler/FeatureMerge.java
+++ b/planetiler-core/src/main/java/com/onthegomap/planetiler/FeatureMerge.java
@@ -87,25 +87,30 @@ public static List<VectorTile.Feature> mergeLineStrings(List<VectorTile.Feature>
     return mergeLineStrings(features, minLength, tolerance, buffer, false);
   }
 
+  /** Merges points with the same attributes into multipoints. */
   public static List<VectorTile.Feature> mergeMultiPoint(List<VectorTile.Feature> features) {
-    return mergeGeometries(
-      features,
-      GeometryType.POINT
-    );
+    return mergeGeometries(features, GeometryType.POINT);
   }
 
+  /**
+   * Merges polygons with the same attributes into multipolygons.
+   * <p>
+   * NOTE: This does not attempt to combine overlapping geometries, see {@link #mergeOverlappingPolygons(List, double)}
+   * or {@link #mergeNearbyPolygons(List, double, double, double, double)} for that.
+   */
   public static List<VectorTile.Feature> mergeMultiPolygon(List<VectorTile.Feature> features) {
-    return mergeGeometries(
-      features,
-      GeometryType.POLYGON
-    );
+    return mergeGeometries(features, GeometryType.POLYGON);
   }
 
+  /**
+   * Merges linestrings with the same attributes into multilinestrings.
+   * <p>
+   * NOTE: This does not attempt to connect linestrings that intersect at endpoints, see
+   * {@link #mergeLineStrings(List, double, double, double, boolean)} for that. Also, this removes extra detail that was
+   * preserved to improve connected-linestring merging, so you should only use one or the other.
+   */
   public static List<VectorTile.Feature> mergeMultiLineString(List<VectorTile.Feature> features) {
-    return mergeGeometries(
-      features,
-      GeometryType.LINE
-    );
+    return mergeGeometries(features, GeometryType.LINE);
   }
 
   private static List<VectorTile.Feature> mergeGeometries(
diff --git a/planetiler-core/src/test/java/com/onthegomap/planetiler/FeatureMergeTest.java b/planetiler-core/src/test/java/com/onthegomap/planetiler/FeatureMergeTest.java
index 1d8d45955e..3402910b75 100644
--- a/planetiler-core/src/test/java/com/onthegomap/planetiler/FeatureMergeTest.java
+++ b/planetiler-core/src/test/java/com/onthegomap/planetiler/FeatureMergeTest.java
@@ -11,11 +11,9 @@
 import com.onthegomap.planetiler.geo.GeometryType;
 import com.onthegomap.planetiler.mbtiles.Mbtiles;
 import java.io.IOException;
-import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
-import java.util.Random;
 import java.util.function.Function;
 import java.util.function.IntFunction;
 import java.util.function.UnaryOperator;
@@ -725,23 +723,6 @@ void mergeMultiline() throws GeometryException {
     );
   }
 
-
-  public static void main(String[] args) {
-    List<VectorTile.Feature> features = new ArrayList<>();
-    Random r = new Random(0);
-    for (int i = 0; i < 100_000; i++) {
-      var lineString = newPoint(r.nextDouble(256), r.nextDouble(256));
-      features.add(new VectorTile.Feature("layer", i, VectorTile.encodeGeometry(lineString), Map.of("a", 1)));
-    }
-    for (int j = 0; j < 10; j++) {
-      long start = System.currentTimeMillis();
-      for (int i = 0; i < 1_000; i++) {
-        FeatureMerge.mergeMultiLineString(features);
-      }
-      System.err.println(System.currentTimeMillis() - start);
-    }
-  }
-
   <S extends Geometry, M extends GeometryCollection> void testMultigeometryMerger(
     IntFunction<S> generateGeometry,
     Function<List<S>, M> combineJTS,