vtknestedfunction.hh

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#ifndef VTK_NESTED_FUNCTION_HH
#define VTK_NESTED_FUNCTION_HH
 
#include <string>
 
#include <dune/common/fvector.hh>
#include <dune/istl/bvector.hh>
#include <dune/grid/io/file/vtk/function.hh>
 
namespace Dumux {

template <class GridView, class Mapper, class Buffer>
class VtkNestedFunction : public Dune::VTKFunction<GridView>
{
    enum { dim = GridView::dimension };
    using ctype = typename GridView::ctype;
    using Element = typename GridView::template Codim<0>::Entity;
    using ReferenceElements = Dune::ReferenceElements<ctype, dim>;
 
public:
    VtkNestedFunction(std::string name,
                      const GridView &gridView,
                      const Mapper &mapper,
                      const Buffer &buf,
                      int codim,
                      int numComp)
        : name_(name)
        , gridView_(gridView)
        , mapper_(mapper)
        , buf_(buf)
        , codim_(codim)
        , numComp_(numComp)
    {
        assert(std::size_t(buf_.size()) == std::size_t(mapper_.size()));
    }
 
    virtual std::string name () const
    { return name_; }
 
    virtual int ncomps() const
    { return numComp_; }
 
    virtual double evaluate(int mycomp,
                            const Element &element,
                            const Dune::FieldVector< ctype, dim > &xi) const
    {
        int idx;
        if (codim_ == 0) {
            // cells. map element to the index
            idx = mapper_.index(element);
        }
        else if (codim_ == dim) {
            // find vertex which is closest to xi in local
            // coordinates. This code is based on Dune::P1VTKFunction
            double min=1e100;
            int imin=-1;
            Dune::GeometryType geomType = element.type();
            int n = element.subEntities(dim);
 
            for (int i=0; i < n; ++i)
            {
                Dune::FieldVector<ctype,dim> local =
                    ReferenceElements::general(geomType).position(i,dim);
                local -= xi;
                if (local.infinity_norm()<min)
                {
                    min = local.infinity_norm();
                    imin = i;
                }
            }
 
            // map vertex to an index
            idx = mapper_.subIndex(element, imin, codim_);
        }
        else
            DUNE_THROW(Dune::InvalidStateException,
                       "Only element and vertex based vector "
                       " fields are supported so far.");
 
        double val = buf_[idx][mycomp];
        using std::abs;
        if (abs(val) < std::numeric_limits<float>::min())
            val = 0;
 
        return val;
    }
 
private:
    const std::string name_;
    const GridView gridView_;
    const Mapper &mapper_;
    const Buffer &buf_;
    int codim_;
    int numComp_;
};
 
} // end namespace Dumux
 
#endif