added functionality for flipping elements

MeshLib/MeshEditing/FlipElements.cpp

+/**
+ * \copyright
+ * Copyright (c) 2012-2016, OpenGeoSys Community (http://www.opengeosys.org)
+ *            Distributed under a Modified BSD License.
+ *              See accompanying file LICENSE.txt or
+ *              http://www.opengeosys.org/project/license
+ *
+ */
+
+#include "FlipElements.h"
+
+#include "MeshLib/Elements/Element.h"
+#include "MeshLib/Node.h"
+#include "MeshLib/Elements/Line.h"
+#include "MeshLib/Elements/Tri.h"
+#include "MeshLib/Elements/Quad.h"
+#include "DuplicateMeshComponents.h"
+
+namespace MeshLib
+{
+
+MeshLib::Element* flipElement(MeshLib::Element const& elem, std::vector<MeshLib::Node*> const& nodes)
+{
+	if (elem.getDimension()>2)
+		return nullptr;
+
+	std::size_t const n_nodes (elem.getNNodes());
+	MeshLib::Node** elem_nodes = new MeshLib::Node*[n_nodes];
+	for (unsigned i=0; i<n_nodes; ++i)
+		elem_nodes[i] = nodes[elem.getNode(i)->getID()];
+	MeshLib::Node* tmp (elem_nodes[0]);
+	elem_nodes[0] = elem_nodes[1];
+	elem_nodes[1] = tmp;
+
+	if (elem.getGeomType() == MeshElemType::LINE)
+		return new MeshLib::Line(elem_nodes, elem.getID());
+	else if (elem.getGeomType() == MeshElemType::TRIANGLE)
+		return new MeshLib::Tri(elem_nodes, elem.getID());
+	else if (elem.getGeomType() == MeshElemType::QUAD)
+	{
+		tmp = elem_nodes[2];
+		elem_nodes[2] = elem_nodes[3];
+		elem_nodes[3] = tmp;
+		return new MeshLib::Quad(elem_nodes, elem.getID());
+	}
+
+	return nullptr;
+}
+
+MeshLib::Mesh* flipMeshElements(MeshLib::Mesh const& mesh)
+{
+	if (mesh.getDimension() > 2)
+		return nullptr;
+
+	std::vector<MeshLib::Node*> new_nodes (MeshLib::copyNodeVector(mesh.getNodes()));
+	std::vector<MeshLib::Element*> const& elems (mesh.getElements());
+	std::vector<MeshLib::Element*> new_elems;
+	std::size_t n_elems (mesh.getNElements());
+	new_elems.reserve(n_elems);
+	
+	for (std::size_t i=0; i<n_elems; ++i)
+		new_elems.push_back(flipElement(*elems[i], new_nodes));
+
+	MeshLib::Properties new_props (mesh.getProperties());
+	return new MeshLib::Mesh("FlippedElementMesh", new_nodes, new_elems, new_props);
+}
+
+} // end namespace MeshLib
+

MeshLib/MeshEditing/FlipElements.h

+/**
+ * \copyright
+ * Copyright (c) 2012-2016, OpenGeoSys Community (http://www.opengeosys.org)
+ *            Distributed under a Modified BSD License.
+ *              See accompanying file LICENSE.txt or
+ *              http://www.opengeosys.org/project/license
+ *
+ */
+
+#ifndef FLIPELEMENTS_H_
+#define FLIPELEMENTS_H_
+
+#include <vector>
+#include "MeshLib/Elements/Element.h"
+
+namespace MeshLib
+{
+class Mesh;
+class Node;
+
+/**
+ * Reverses the node order of a 1D / 2D element such that the direction 
+ * of a line changes and normals of 2D elements changes its sign.
+ */
+MeshLib::Element* flipElement(MeshLib::Element const& elem, std::vector<MeshLib::Node*> const& nodes);
+
+/**
+ * Reverses the node order of all elements in a 1D / 2D mesh such that 
+ * the direction of lines changes and normals of 2D elements changes 
+ * their sign.
+ */
+MeshLib::Mesh* flipMeshElements(MeshLib::Mesh const& mesh);
+
+}
+
+#endif //FLIPELEMENTS_H_