bugfix: fix exporting of the mesh contours for polygons. now the exported polygons does not match triangular mesh

PeterPetrik · PeterPetrik · commit cf36172e3322 · 2020-01-15T12:31:11.000+01:00
diff --git a/src/analysis/mesh/qgsmeshcontours.cpp b/src/analysis/mesh/qgsmeshcontours.cpp
@@ -196,17 +196,44 @@ QgsGeometry QgsMeshContours::exportPolygons(
         }
         else
         {
-          // nothing here, we are outside the range
-          continue;
+          // last option we need to consider is that both min and max are between
+          // value i and j, and in that case we need to calculate both point
+          double value1 = max_value;
+          double value2 = max_value;
+          if ( values[i] < values[j] )
+          {
+            if ( ( min_value < values[i] ) || ( max_value > values[j] ) )
+            {
+              continue;
+            }
+            value1 = min_value;
+          }
+          else
+          {
+            if ( ( min_value < values[j] ) || ( max_value > values[i] ) )
+            {
+              continue;
+            }
+            value2 = min_value;
+          }
+
+          const double fraction1 = ( value1 - values[i] ) / ( values[j] - values[i] );
+          const QgsPoint xy1 = QgsGeometryUtils::interpolatePointOnLine( coords[i], coords[j], fraction1 );
+          if ( !ring.contains( xy1 ) )
+            ring.push_back( xy1 );
+
+          const double fraction2 = ( value2 - values[i] ) / ( values[j] - values[i] );
+          const QgsPoint xy2 = QgsGeometryUtils::interpolatePointOnLine( coords[i], coords[j], fraction2 );
+          if ( !ring.contains( xy2 ) )
+            ring.push_back( xy2 );
         }
       }
     }
 
     // add if the polygon is not degraded
     if ( ring.size() > 2 )
     {
-      ring.push_back( coords[0] );
-      std::unique_ptr< QgsLineString > ext = qgis::make_unique< QgsLineString> ( coords );
+      std::unique_ptr< QgsLineString > ext = qgis::make_unique< QgsLineString> ( ring );
       std::unique_ptr< QgsPolygon > poly = qgis::make_unique< QgsPolygon >();
       poly->setExteriorRing( ext.release() );
       multiPolygon.push_back( QgsGeometry( std::move( poly ) ) );
diff --git a/tests/src/analysis/testqgsmeshcontours.cpp b/tests/src/analysis/testqgsmeshcontours.cpp
@@ -168,9 +168,10 @@ void TestQgsMeshContours::testQuadAndTriangleVertexScalarPoly_data()
   QTest::addColumn< double >( "max_value" );
   QTest::addColumn< QgsGeometry >( "expected" );
 
-  QTest::newRow( "left" ) <<  1.0 << 1.5 << QgsGeometry( QgsGeometryFactory::geomFromWkt( "PolygonZ ((1000 2000 20, 1000 3000 10, 2000 3000 50, 2000 2000 30, 1000 2000 20))" ) );
-  QTest::newRow( "middle" ) <<  1.5 << 2.0 << QgsGeometry( QgsGeometryFactory::geomFromWkt( "PolygonZ ((1000 2000 20, 1000 3000 10, 2000 3000 50, 2000 2000 30, 1000 2000 20))" ) );
-  QTest::newRow( "right" ) <<  2.0 << 2.5 << QgsGeometry( QgsGeometryFactory::geomFromWkt( "PolygonZ ((3000 2000 40, 2000 3000 50, 2000 2000 30, 3000 2000 40))" ) );
+  QTest::newRow( "left" ) <<  1.0 << 1.5 << QgsGeometry( QgsGeometryFactory::geomFromWkt( "PolygonZ ((1500 2500 35, 1500 2000 25, 1000 2000 20, 1000 3000 10, 1500 3000 30, 1500 2500 35))" ) );
+  QTest::newRow( "bothinsquare" ) <<  1.2 << 1.4 << QgsGeometry( QgsGeometryFactory::geomFromWkt( "PolygonZ ((1400 2400 32, 1400 2000 24, 1200 2000 22, 1200 2200 26, 1200 3000 18, 1400 3000 25.99999999999999645, 1400 2400 32))" ) );
+  QTest::newRow( "middle" ) <<  1.5 << 2.0 << QgsGeometry( QgsGeometryFactory::geomFromWkt( "PolygonZ ((2000 3000 50, 2000 2000 30, 1500 2000 25, 1500 2500 35, 1500 3000 30, 2000 3000 50))" ) );
+  QTest::newRow( "right" ) <<  2.0 << 2.5 << QgsGeometry( QgsGeometryFactory::geomFromWkt( "PolygonZ ((2500 2500 45, 2000 3000 50, 2000 2000 30, 2500 2000 35, 2500 2500 45))" ) );
 
   QTest::newRow( "outside_left_edge" ) <<  0.0 << 1.0 << QgsGeometry();
   QTest::newRow( "only one point" ) << 3.0 << 3.0 << QgsGeometry();
@@ -198,9 +199,9 @@ void TestQgsMeshContours::testQuadAndTriangleFaceScalarPoly_data()
   QTest::addColumn< double >( "max_value" );
   QTest::addColumn< QgsGeometry >( "expected" );
 
-  QTest::newRow( "left" ) << 1.0 << 1.25 << QgsGeometry( QgsGeometryFactory::geomFromWkt( "PolygonZ ((1000 2000 20, 1000 3000 10, 2000 3000 50, 2000 2000 30, 1000 2000 20))" ) );
-  QTest::newRow( "middle" ) << 1.25 << 1.5 <<  QgsGeometry( QgsGeometryFactory::geomFromWkt( "PolygonZ ((1000 2000 20, 1000 3000 10, 2000 3000 50, 2000 2000 30, 1000 2000 20))" ) );
-  QTest::newRow( "right" ) <<  1.5 << 1.75 << QgsGeometry( QgsGeometryFactory::geomFromWkt( "PolygonZ ((3000 2000 40, 2000 3000 50, 2000 2000 30, 3000 2000 40))" ) );
+  QTest::newRow( "left" ) << 1.0 << 1.25 << QgsGeometry( QgsGeometryFactory::geomFromWkt( "PolygonZ ((1500 2500 35, 1500 2000 25, 1000 2000 20, 1000 3000 10, 1500 3000 30, 1500 2500 35))" ) );
+  QTest::newRow( "middle" ) << 1.25 << 1.5 <<  QgsGeometry( QgsGeometryFactory::geomFromWkt( "PolygonZ ((2000 3000 50, 2000 2000 30, 1500 2000 25, 1500 2500 35, 1500 3000 30, 2000 3000 50))" ) );
+  QTest::newRow( "right" ) <<  1.5 << 1.75 << QgsGeometry( QgsGeometryFactory::geomFromWkt( "PolygonZ ((2500 2500 45, 2000 3000 50, 2000 2000 30, 2500 2000 35, 2500 2500 45))" ) );
 
   QTest::newRow( "only one point" ) << 2.0 << 2.0 << QgsGeometry();
   QTest::newRow( "outside lower" ) << -3.0 << -4.0 << QgsGeometry();
