[geos-commits] [SCM] GEOS branch 3.7 updated. 6f305213fd544d21a09d5c802d8ac82cef576687

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- Log -----------------------------------------------------------------
commit 6f305213fd544d21a09d5c802d8ac82cef576687
Author: Paul Ramsey <pramsey at cleverelephant.ca>
Date:   Wed Aug 21 13:01:28 2019 -0700

    Port fix to regression in union algorithm from master

diff --git a/NEWS b/NEWS
index 59788c3..97cbdd9 100644
--- a/NEWS
+++ b/NEWS
@@ -2,7 +2,7 @@ Changes in 3.7.3dev
 2019-XX-XX
 
 - Bug fixes / improvements
-  -
+  - Union performance regression (#867 Paul Ramsey)
 
 
 Changes in 3.7.2
diff --git a/src/operation/union/CascadedPolygonUnion.cpp b/src/operation/union/CascadedPolygonUnion.cpp
index 56b43c4..23a1aaf 100644
--- a/src/operation/union/CascadedPolygonUnion.cpp
+++ b/src/operation/union/CascadedPolygonUnion.cpp
@@ -260,7 +260,7 @@ CascadedPolygonUnion::unionUsingEnvelopeIntersection(geom::Geometry* g0,
     check_valid(*g1Int, "unionUsingEnvelopeIntersection g1Int");
 #endif
 
-    std::unique_ptr<geom::Geometry> u(unionActual(g0Int.get(), g1Int.get()));
+    std::unique_ptr<geom::Geometry> unionCommon(unionActual(g0Int.get(), g1Int.get()));
 
 #if GEOS_DEBUG_CASCADED_UNION
     if ( ! check_valid(*u, "unionUsingEnvelopeIntersection unionActual return") )
@@ -278,7 +278,7 @@ CascadedPolygonUnion::unionUsingEnvelopeIntersection(geom::Geometry* g0,
     }
 #endif
 
-    if ( disjointPolys.empty() ) return u.release();
+    if ( disjointPolys.empty() ) return unionCommon.release();
 
 #if GEOS_DEBUG_CASCADED_UNION
     for ( size_t i=0; i<disjointPolys.size(); ++i )
@@ -288,28 +288,36 @@ CascadedPolygonUnion::unionUsingEnvelopeIntersection(geom::Geometry* g0,
     }
 #endif
 
-    // TODO: find, in disjointPolys, those which now have their
-    // environment intersect the environment of the union "u"
-    // and collect them in another vector to be unioned
+    geom::Envelope const* unionCommonEnv = unionCommon->getEnvelopeInternal(); // TODO: check for EMPTY ?
 
     std::vector<geom::Geometry*> polysOn;
     std::vector<geom::Geometry*> polysOff;
-    geom::Envelope const* uEnv = u->getEnvelopeInternal(); // TODO: check for EMPTY ?
-    extractByEnvelope(*uEnv, disjointPolys, polysOn, polysOff);
+    extractByEnvelope(*unionCommonEnv, disjointPolys, polysOn, polysOff);
 #if GEOS_DEBUG_CASCADED_UNION
     std::cerr << "unionUsingEnvelopeIntersection: " << polysOn.size() << "/" << disjointPolys.size() << " polys intersect union of final thing" << std::endl;
 #endif
 
+    // If the union of the interacting geometries
+    // is contained in the envelope of the inputs
+    // (and this is highly likely unless overlay robustness failure occurs)
+    // it is safe to combine with the disjoint polygons
+    geom::Envelope beforeUnionEnv( *(g0Int->getEnvelopeInternal()) );
+    beforeUnionEnv.expandToInclude( g1Int->getEnvelopeInternal() );
+    bool isUnionSafe = beforeUnionEnv.contains(unionCommonEnv);
+    //if (! isUnionSafe) std::cerr << "Found unsafe union" << std::endl;
+
     std::unique_ptr<geom::Geometry> ret;
-    if ( polysOn.empty() ) {
-      disjointPolys.push_back(u.get());
+    if(polysOn.empty() || isUnionSafe) {
+      disjointPolys.push_back(unionCommon.get());
       ret.reset( geom::util::GeometryCombiner::combine(disjointPolys));
     } else {
+      // The union envelope changed (e.g. due to snapping heuristics)
+      // so to be safe must union everything (which is slow, but infrequent)
       // TODO: could be further tweaked to only union with polysOn
       //       and combine with polysOff, but then it'll need again to
       //       recurse in the check for disjoint/intersecting
-      ret.reset( geom::util::GeometryCombiner::combine(disjointPolys) );
-      ret.reset( unionActual(ret.get(), u.get()) );
+      std::unique_ptr<geom::Geometry> disjointCombined( geom::util::GeometryCombiner::combine(disjointPolys) );
+      ret.reset( unionActual( disjointCombined.get(), unionCommon.get() ) );
     }
 
 #if GEOS_DEBUG_CASCADED_UNION

-----------------------------------------------------------------------

Summary of changes:
 NEWS                                         |  2 +-
 src/operation/union/CascadedPolygonUnion.cpp | 30 ++++++++++++++++++----------
 2 files changed, 20 insertions(+), 12 deletions(-)


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