more robust line/multiline splitting

mhugent · mhugent · commit 8485f0b3cad0 · 2008-01-30T10:14:40.000Z
git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@8095 c8812cc2-4d05-0410-92ff-de0c093fc19c
diff --git a/src/core/qgsgeometry.cpp b/src/core/qgsgeometry.cpp
@@ -4576,10 +4576,14 @@ int QgsGeometry::splitLinearGeometry(GEOS_GEOM::LineString* splitLine, QList<Qgs
   QList<GEOS_GEOM::Geometry*> testedGeometries;
   GEOS_GEOM::Geometry* intersectGeom = 0;
 
+  //hardcoded thresholds
+  double bufferDistance = 0.000000001;
+  double intersectThreshold =  0.0000001;
+
   for(unsigned int i = 0; i < mergedLineStrings->size(); ++i)
     {
-      intersectGeom = mGeos->intersection((*mergedLineStrings)[i]);
-      if(intersectGeom->getLength() > 0.00000001)
+      intersectGeom = mGeos->intersection((*mergedLineStrings)[i]->buffer(bufferDistance));
+      if(intersectGeom->getLength() > intersectThreshold)
 	{
 	  testedGeometries.push_back((*mergedLineStrings)[i]);
 	}

Original file line number	Diff line number	Diff line change
`@@ -4576,10 +4576,14 @@ int QgsGeometry::splitLinearGeometry(GEOS_GEOM::LineString* splitLine, QList<Qgs`
`4576`	`4576`	`QList<GEOS_GEOM::Geometry*> testedGeometries;`
`4577`	`4577`	`GEOS_GEOM::Geometry* intersectGeom = 0;`
`4578`	`4578`
	`4579`	`+ //hardcoded thresholds`
	`4580`	`+ double bufferDistance = 0.000000001;`
	`4581`	`+ double intersectThreshold = 0.0000001;`
	`4582`	`+`
`4579`	`4583`	`for(unsigned int i = 0; i < mergedLineStrings->size(); ++i)`
`4580`	`4584`	`{`
`4581`		`- intersectGeom = mGeos->intersection((*mergedLineStrings)[i]);`
`4582`		`- if(intersectGeom->getLength() > 0.00000001)`
	`4585`	`+ intersectGeom = mGeos->intersection((*mergedLineStrings)[i]->buffer(bufferDistance));`
	`4586`	`+ if(intersectGeom->getLength() > intersectThreshold)`
`4583`	`4587`	`{`
`4584`	`4588`	`testedGeometries.push_back((*mergedLineStrings)[i]);`
`4585`	`4589`	`}`