From 4907d593aa6aa31c25dbe73933bf66995a04e498 Mon Sep 17 00:00:00 2001
From: Paul Ramsey <pramsey@cleverelephant.ca>
Date: Thu, 25 Jul 2024 11:41:01 -0700
Subject: [PATCH] Add envelope condition in support of RelateNG

---
 .../MCIndexSegmentSetMutualIntersector.h      | 21 ++++++++++++++++---
 .../MCIndexSegmentSetMutualIntersector.cpp    | 13 ++++++++++--
 2 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/include/geos/noding/MCIndexSegmentSetMutualIntersector.h b/include/geos/noding/MCIndexSegmentSetMutualIntersector.h
index abc687919d..12fe5d8b3e 100644
--- a/include/geos/noding/MCIndexSegmentSetMutualIntersector.h
+++ b/include/geos/noding/MCIndexSegmentSetMutualIntersector.h
@@ -20,12 +20,15 @@
 #include <geos/index/strtree/TemplateSTRtree.h> // inherited
 
 namespace geos {
+namespace geom {
+    class Envelope;
+}
 namespace index {
-class SpatialIndex;
+    class SpatialIndex;
 }
 namespace noding {
-class SegmentString;
-class SegmentIntersector;
+    class SegmentString;
+    class SegmentIntersector;
 }
 }
 
@@ -51,6 +54,17 @@ class MCIndexSegmentSetMutualIntersector : public SegmentSetMutualIntersector {
         , nOverlaps(0)
         , overlapTolerance(p_tolerance)
         , indexBuilt(false)
+        , envelope(nullptr)
+    {}
+
+    MCIndexSegmentSetMutualIntersector(const geom::Envelope* p_envelope)
+        : monoChains()
+        , indexCounter(0)
+        , processCounter(0)
+        , nOverlaps(0)
+        , overlapTolerance(0.0)
+        , indexBuilt(false)
+        , envelope(p_envelope)
     {}
 
     MCIndexSegmentSetMutualIntersector()
@@ -117,6 +131,7 @@ class MCIndexSegmentSetMutualIntersector : public SegmentSetMutualIntersector {
      */
     bool indexBuilt;
     MonoChains indexChains;
+    const geom::Envelope* envelope;
 
     void addToIndex(SegmentString* segStr);
 
diff --git a/src/noding/MCIndexSegmentSetMutualIntersector.cpp b/src/noding/MCIndexSegmentSetMutualIntersector.cpp
index 148ace410c..b5b5e4d490 100644
--- a/src/noding/MCIndexSegmentSetMutualIntersector.cpp
+++ b/src/noding/MCIndexSegmentSetMutualIntersector.cpp
@@ -12,6 +12,7 @@
  *
  **********************************************************************/
 
+#include <geos/geom/Envelope.h>
 #include <geos/noding/MCIndexSegmentSetMutualIntersector.h>
 #include <geos/noding/SegmentSetMutualIntersector.h>
 #include <geos/noding/SegmentString.h>
@@ -47,8 +48,14 @@ MCIndexSegmentSetMutualIntersector::addToMonoChains(SegmentString* segStr)
 {
     if (segStr->size() == 0)
         return;
+    MonoChains segChains;
     MonotoneChainBuilder::getChains(segStr->getCoordinates(),
-                                    segStr, monoChains);
+                                    segStr, segChains);
+    for (auto& mc : segChains) {
+        if (envelope == nullptr || envelope->intersects(mc.getEnvelope())) {
+            monoChains.push_back(mc);
+        }
+    }
 }
 
 
@@ -89,7 +96,9 @@ MCIndexSegmentSetMutualIntersector::process(SegmentString::ConstVect* segStrings
 {
     if (!indexBuilt) {
         for (auto& mc: indexChains) {
-            index.insert(&(mc.getEnvelope(overlapTolerance)), &mc);
+            if (envelope == nullptr || envelope->intersects(mc.getEnvelope())) {
+                index.insert(&(mc.getEnvelope(overlapTolerance)), &mc);
+            }
         }
         indexBuilt = true;
     }