From d2aaeb2988b95d7be3c9601faa4e1cb6e2132ae4 Mon Sep 17 00:00:00 2001
From: Arndt Brenschede <Arndt.Brenschede@web.de>
Date: Sun, 4 Aug 2019 10:22:50 +0200
Subject: [PATCH] Douglas-Peucker transfer-node elimination on pre-processor
 level

---
 .../main/java/btools/mapcreator/DPFilter.java | 19 +++++++++++++++++++
 .../main/java/btools/mapcreator/OsmNodeP.java |  2 +-
 .../java/btools/mapcreator/WayLinker.java     |  2 ++
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/brouter-map-creator/src/main/java/btools/mapcreator/DPFilter.java b/brouter-map-creator/src/main/java/btools/mapcreator/DPFilter.java
index b23d50b..2310fd1 100644
--- a/brouter-map-creator/src/main/java/btools/mapcreator/DPFilter.java
+++ b/brouter-map-creator/src/main/java/btools/mapcreator/DPFilter.java
@@ -16,6 +16,25 @@ public class DPFilter
   /*
    * for each node (except first+last), eventually set the DP_SURVIVOR_BIT
    */
+  public static void doDPFilter( ArrayList<OsmNodeP> nodes )
+  {
+    int first = 0;
+    int last = nodes.size()-1;
+    while( first < last && (nodes.get(first+1).bits & OsmNodeP.DP_SURVIVOR_BIT) != 0 )
+    {
+      first++;
+    }
+    while( first < last && (nodes.get(last-1).bits & OsmNodeP.DP_SURVIVOR_BIT) != 0 )
+    {
+      last--;
+    }
+    if ( last - first > 1 )
+    {
+      doDPFilter( nodes, first, last );
+    }
+  }
+    
+
   public static void doDPFilter( ArrayList<OsmNodeP> nodes, int first, int last )
   {
     double maxSqDist = -1.;
diff --git a/brouter-map-creator/src/main/java/btools/mapcreator/OsmNodeP.java b/brouter-map-creator/src/main/java/btools/mapcreator/OsmNodeP.java
index dd70c65..1fa1fd0 100644
--- a/brouter-map-creator/src/main/java/btools/mapcreator/OsmNodeP.java
+++ b/brouter-map-creator/src/main/java/btools/mapcreator/OsmNodeP.java
@@ -252,7 +252,7 @@ public class OsmNodeP extends OsmLinkP
       mc.writeModeAndDesc( isReverse, link0.descriptionBitmap );
       if ( !isReverse && linkNodes.size() > 2 ) // write geometry for forward links only
       {
-        DPFilter.doDPFilter( linkNodes, 0, linkNodes.size()-1 );
+        DPFilter.doDPFilter( linkNodes );
         origin = this;
         for( int i=1; i<linkNodes.size()-1; i++ )
         {
diff --git a/brouter-map-creator/src/main/java/btools/mapcreator/WayLinker.java b/brouter-map-creator/src/main/java/btools/mapcreator/WayLinker.java
index 7f7157a..ef40dc3 100644
--- a/brouter-map-creator/src/main/java/btools/mapcreator/WayLinker.java
+++ b/brouter-map-creator/src/main/java/btools/mapcreator/WayLinker.java
@@ -237,6 +237,7 @@ public class WayLinker extends MapCreatorBase
         {
           r.fromLon = n1.ilon;
           r.fromLat = n1.ilat;
+          n1.bits |= OsmNodeP.DP_SURVIVOR_BIT;
         }
       }
       if ( r.toWid == wid )
@@ -245,6 +246,7 @@ public class WayLinker extends MapCreatorBase
         {
           r.toLon = n1.ilon;
           r.toLat = n1.ilat;
+          n1.bits |= OsmNodeP.DP_SURVIVOR_BIT;
         }
       }
       r = r.next;