Improvement to polygon splitting

mhugent · mhugent · commit 82894b6b0bba · 2008-01-23T16:07:09.000Z
git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@8034 c8812cc2-4d05-0410-92ff-de0c093fc19c
diff --git a/src/core/qgsgeometry.cpp b/src/core/qgsgeometry.cpp
@@ -4583,10 +4583,16 @@ int QgsGeometry::splitPolygonGeometry(GEOS_GEOM::LineString* splitLine, QList<Qg
   //include in result if yes
   QList<GEOS_GEOM::Geometry*> testedGeometries;
   GEOS_GEOM::Geometry* intersectGeometry = 0;
+  
+  //ratio intersect geometry / geometry. This should be close to 1
+  //if the polygon belongs to the input geometry
+  
+  double areaRatio = 0.0;
   for(unsigned int i = 0; i < polygons->size(); ++i)
     {
       intersectGeometry = mGeos->intersection((*polygons)[i]);
-      if(intersectGeometry->getArea() > 0.00000000001)
+      areaRatio = intersectGeometry->getArea() / (*polygons)[i]->getArea();
+      if(areaRatio > 0.99 && areaRatio < 1.01)
 	{
 	  testedGeometries.push_back((*polygons)[i]);
 	}

Original file line number	Diff line number	Diff line change
`@@ -4583,10 +4583,16 @@ int QgsGeometry::splitPolygonGeometry(GEOS_GEOM::LineString* splitLine, QList<Qg`
`4583`	`4583`	`//include in result if yes`
`4584`	`4584`	`QList<GEOS_GEOM::Geometry*> testedGeometries;`
`4585`	`4585`	`GEOS_GEOM::Geometry* intersectGeometry = 0;`
	`4586`	`+`
	`4587`	`+ //ratio intersect geometry / geometry. This should be close to 1`
	`4588`	`+ //if the polygon belongs to the input geometry`
	`4589`	`+`
	`4590`	`+ double areaRatio = 0.0;`
`4586`	`4591`	`for(unsigned int i = 0; i < polygons->size(); ++i)`
`4587`	`4592`	`{`
`4588`	`4593`	`intersectGeometry = mGeos->intersection((*polygons)[i]);`
`4589`		`- if(intersectGeometry->getArea() > 0.00000000001)`
	`4594`	`+ areaRatio = intersectGeometry->getArea() / (*polygons)[i]->getArea();`
	`4595`	`+ if(areaRatio > 0.99 && areaRatio < 1.01)`
`4590`	`4596`	`{`
`4591`	`4597`	`testedGeometries.push_back((*polygons)[i]);`
`4592`	`4598`	`}`