elements.h

Go to the documentation of this file.

/*!
 *
 * Copyright (C) 2015 Technical University of Liberec.  All rights reserved.
 * 
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License version 3 as published by the
 * Free Software Foundation. (http://www.gnu.org/licenses/gpl-3.0.en.html)
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
 *
 * 
 * @file    elements.h
 * @brief   
 */

#ifndef ELEMENTS_H
#define ELEMENTS_H

#include "mesh/nodes.hh"
#include "mesh/region.hh"
#include "mesh/bounding_box.hh"
#include "mesh/ref_element.hh"

template <int spacedim>
class ElementAccessor;

class Mesh;
class Side;
class SideIter;
class Neighbour;



//=============================================================================
// STRUCTURE OF THE ELEMENT OF THE MESH
//=============================================================================
class Element
{
public:
    Element();
    Element(unsigned int dim, Mesh *mesh_in, RegionIdx reg);
    void init(unsigned int dim, Mesh *mesh_in, RegionIdx reg);
    ~Element();


    inline unsigned int dim() const;
    inline unsigned int index() const;
    unsigned int n_sides() const;    // Number of sides
    unsigned int n_nodes() const; // Number of nodes
    
    ///Gets ElementAccessor of this element
    ElementAccessor<3> element_accessor() const;
    
    double measure() const;
    arma::vec3 centre() const;
    /**
     * Quality of the element based on the smooth and scale-invariant quality measures proposed in:
     * J. R. Schewchuk: What is a Good Linear Element?
     *
     * We scale the measure so that is gives value 1 for regular elements. Line 1d elements
     * have always quality 1.
     */
    double quality_measure_smooth();

    unsigned int n_sides_by_dim(unsigned int side_dim);
    inline SideIter side(const unsigned int loc_index);
    inline const SideIter side(const unsigned int loc_index) const;
    Region region() const;
    inline RegionIdx region_idx() const
        { return region_idx_; }
    
    unsigned int id() const;

    int      pid;       // Id # of mesh partition

    // Type specific data
    Node** node;    // Element's nodes


    unsigned int *edge_idx_; // Edges on sides
    unsigned int *boundary_idx_; // Possible boundaries on sides (REMOVE) all bcd assembly should be done through iterating over boundaries
                           // ?? deal.ii has this not only boundary iterators
    /**
     * Indices of permutations of nodes on sides.
     * It determines, in which order to take the nodes of the side so as to obtain
     * the same order as on the reference side (side 0 on the particular edge).
     *
     * Permutations are defined in RefElement::side_permutations.
     */
    unsigned int *permutation_idx_;

    /**
     * Computes bounding box of element (OBSOLETE)
     */
    void get_bounding_box(BoundingBox &bounding_box) const;

    /**
     * Return bounding box of the element.
     */
    inline BoundingBox bounding_box() {
        return BoundingBox(this->vertex_list());
    }

    /**
     * Map from reference element to global coord system.
     * Matrix(3, dim()+1), last column is the translation vector.
     *
     * Temporary, this should be provided be a separate finite element mapping class.
     */
    inline arma::mat element_map() const
    {
        arma::vec3 &v0 = node[0]->point();
        arma::mat A(3, dim()+1);

        for(unsigned int i=0; i < dim(); i++ ) {
            A.col(i) = node[i+1]->point() - v0;
        }
        A.col(dim()) = v0;
        return A;
    }

    /**
     * Project given point to the barycentic coordinates.
     * Result vector have dimension dim()+1. Local coordinates are the first.
     * Last is 1-...
     */
    arma::vec project_point(const arma::vec3 &point, const arma::mat &map) const;


    /**
     * Project a point and create the map as well.
     */
    inline arma::vec project_point(const arma::vec3 &point) {
        return project_point(point, this->element_map() );
    }

    /**
     * Clip a point given by barycentric cocordinates to the element.
     * If the point is out of the element the closest point
     * projection to the element surface is used.
     */
    inline arma::vec clip_to_element(arma::vec &barycentric) {
       switch (dim()) {
                case 1: return RefElement<1>::clip(barycentric);
                case 2: return RefElement<2>::clip(barycentric);
                case 3: return RefElement<3>::clip(barycentric);
                default: ASSERT(false).error("Clipping supported only for dim=1,2,3.");
        }
        return barycentric; // should never happen
    }

    /**
     * Return list of element vertices.
     */
    inline vector<arma::vec3> vertex_list() {
        vector<arma::vec3> vertices(this->n_nodes());
        for(unsigned int i=0; i<n_nodes(); i++) vertices[i]=node[i]->point();
        return vertices;
    }


    unsigned int      n_neighs_vb;   // # of neighbours, V-B type (comp.)
                            // only ngh from this element to higher dimension edge
    Neighbour **neigh_vb; // List og neighbours, V-B type (comp.)


    Mesh    *mesh_; // should be removed as soon as the element is also an Accessor


protected:
    // Data readed from mesh file
    RegionIdx  region_idx_;
    unsigned int dim_;

    friend class Mesh;

    template<int spacedim, class Value>
    friend class Field;

};




#define FOR_ELEMENT_NODES(i,j)  for((j)=0;(j)<(i)->n_nodes();(j)++)
#define FOR_ELEMENT_SIDES(i,j)  for(unsigned int j=0; j < (i)->n_sides(); j++)
#define FOR_ELM_NEIGHS_VB(i,j)  for((j)=0;(j)<(i)->n_neighs_vb;(j)++)


#endif
//-----------------------------------------------------------------------------
// vim: set cindent: