From 0d6c93d96f782e3ae308c79ad3692c5a0180700c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jacob=20St=C3=B8ren?= <jacob.storen@ceetronsolutions.com>
Date: Thu, 16 Jan 2020 09:21:31 +0100
Subject: [PATCH] Add experimental test of using clipper to keep edge
 information through the clipping

---
 .../UnitTests/RigCellGeometryTools-Test.cpp   | 134 ++++++++++++++++++
 1 file changed, 134 insertions(+)

diff --git a/ApplicationCode/UnitTests/RigCellGeometryTools-Test.cpp b/ApplicationCode/UnitTests/RigCellGeometryTools-Test.cpp
index 3e43df340c..3c4f22d5a0 100644
--- a/ApplicationCode/UnitTests/RigCellGeometryTools-Test.cpp
+++ b/ApplicationCode/UnitTests/RigCellGeometryTools-Test.cpp
@@ -525,3 +525,137 @@ TEST( RigWellPathStimplanIntersector, intersection )
         }
     }
 }
+
+//////////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Test of whether we can transport edge information trough clipper clipping
+// Seems as if it might be possible, but clipper will ignore the edge information
+// processed by the callback if one of the edges is horizontal
+//
+
+#include "clipper/clipper.hpp"
+double clipperConversionFactor2 = 10000; // For transform to clipper int
+
+ClipperLib::IntPoint toClipperEdgePoint( const cvf::Vec3d& cvfPoint )
+{
+    int xInt = cvfPoint.x() * clipperConversionFactor2;
+    int yInt = cvfPoint.y() * clipperConversionFactor2;
+    int zInt = cvfPoint.z();
+    return ClipperLib::IntPoint( xInt, yInt, zInt );
+}
+
+cvf::Vec3d fromClipperEdgePoint( const ClipperLib::IntPoint& clipPoint )
+{
+    double zDValue;
+
+    if ( clipPoint.Z == std::numeric_limits<int>::max() )
+    {
+        zDValue = HUGE_VAL;
+    }
+    else
+    {
+        zDValue = clipPoint.Z;
+    }
+
+    return cvf::Vec3d( clipPoint.X / clipperConversionFactor2, clipPoint.Y / clipperConversionFactor2, zDValue );
+}
+
+void swapPointsIfNeedeed( ClipperLib::IntPoint*& p1, ClipperLib::IntPoint*& p2 )
+{
+    if ( p1->Z > p2->Z )
+    {
+        std::swap( p1, p2 );
+    }
+
+    if ( ( p2->Z - p1->Z ) > 1 ) // End edge of polygon
+    {
+        std::swap( p1, p2 ); // Swap back
+    }
+}
+
+void clipperEdgeIntersectCallback( ClipperLib::IntPoint& e1bot,
+                                   ClipperLib::IntPoint& e1top,
+                                   ClipperLib::IntPoint& e2bot,
+                                   ClipperLib::IntPoint& e2top,
+                                   ClipperLib::IntPoint& pt )
+{
+    ClipperLib::IntPoint* e11 = &e1bot;
+    ClipperLib::IntPoint* e12 = &e1top;
+    ClipperLib::IntPoint* e21 = &e2bot;
+    ClipperLib::IntPoint* e22 = &e2top;
+
+    swapPointsIfNeedeed( e11, e12 );
+    swapPointsIfNeedeed( e21, e22 );
+
+    cvf::Vec3f e1( e12->X - e11->X, e12->Y - e11->Y, 0.0 );
+    cvf::Vec3f e2( e22->X - e21->X, e22->Y - e21->Y, 0.0 );
+
+    cvf::Vec3f up = e1 ^ e2;
+    if ( up.z() > 0 )
+    {
+        pt.Z = e12->Z;
+        std::cout << "E1 :" << e11->Z << " " << e12->Z << std::endl;
+        std::cout << "E2 :" << e21->Z << " " << e22->Z << std::endl << std::endl;
+    }
+    else
+    {
+        pt.Z = e22->Z;
+        std::cout << "E1 :" << e21->Z << " " << e22->Z << std::endl;
+        std::cout << "E2 :" << e11->Z << " " << e12->Z << std::endl << std::endl;
+    }
+}
+
+TEST( RigCellGeometryTools, ClipperEdgeTracking )
+{
+    // If the first edges of the polygons are horizontal, the edge tracking will fail.
+    // Encode polygon and edge into Z coordinate of the vertex
+
+    std::vector<cvf::Vec3d> polygon1 = {{0.0, 0.51, 1002.0}, {1.0, 0.5, 1000.0}, {0.0, 1.0, 1001.0}};
+    std::vector<cvf::Vec3d> polygon2 = {{0.5, 0.01, 2002.0}, {1.0, 0.0, 2000.0}, {0.5, 1.0, 2001.0}};
+
+    std::vector<std::vector<cvf::Vec3d>> clippedPolygons;
+
+    // Convert to int for clipper library and store as clipper "path"
+    ClipperLib::Path polygon1path;
+    for ( const cvf::Vec3d& v : polygon1 )
+    {
+        polygon1path.push_back( toClipperEdgePoint( v ) );
+    }
+
+    ClipperLib::Path polygon2path;
+    for ( const cvf::Vec3d& v : polygon2 )
+    {
+        polygon2path.push_back( toClipperEdgePoint( v ) );
+    }
+
+    ClipperLib::Clipper clpr;
+    clpr.AddPath( polygon1path, ClipperLib::ptSubject, true );
+    clpr.AddPath( polygon2path, ClipperLib::ptClip, true );
+
+    clpr.ZFillFunction( &clipperEdgeIntersectCallback );
+
+    ClipperLib::Paths solution;
+    clpr.Execute( ClipperLib::ctIntersection, solution, ClipperLib::pftEvenOdd, ClipperLib::pftEvenOdd );
+
+    // Convert back to std::vector<std::vector<cvf::Vec3d> >
+    for ( ClipperLib::Path pathInSol : solution )
+    {
+        std::vector<cvf::Vec3d> clippedPolygon;
+        for ( ClipperLib::IntPoint IntPosition : pathInSol )
+        {
+            clippedPolygon.push_back( fromClipperEdgePoint( IntPosition ) );
+        }
+        clippedPolygons.push_back( clippedPolygon );
+    }
+
+    int pIdx = 1;
+    for ( auto& polygon : clippedPolygons )
+    {
+        std::cout << "Polygon: " << pIdx << std::endl;
+        for ( auto& point : polygon )
+        {
+            std::cout << "   [ " << point[0] << ", " << point[1] << ", " << point[2] << " ]" << std::endl;
+        }
+        pIdx++;
+    }
+}