Voronoi.H

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// Initialize an N component field with a Voronoi tessellation.
// (Mostly used by :code:`Integrator::PhaseFieldMicrostructure`).
 
#ifndef IC_VORONOI_H_
#define IC_VORONOI_H_
 
#include "Set/Set.H"
#include "IC/IC.H"
#include "IO/ParmParse.H"
 
namespace IC
{
class Voronoi : public IC<Set::Scalar>
{
public:
    static constexpr const char* name = "voronoi";
 
    enum Type {Partition, Values};
 
    Voronoi (amrex::Vector<amrex::Geometry> &_geom) : IC(_geom) {}
    Voronoi (amrex::Vector<amrex::Geometry> &_geom,IO::ParmParse &pp, std::string name) : IC(_geom) 
    {pp_queryclass(name,*this);}
    Voronoi (amrex::Vector<amrex::Geometry> &_geom, int _number_of_grains, Set::Scalar a_alpha) : IC(_geom) 
    {
        Define(_number_of_grains,a_alpha);
    }
    Voronoi (amrex::Vector<amrex::Geometry> &a_geom, int a_number_of_grains) : IC(a_geom) 
    {
        Define(a_number_of_grains,1.0);
    }
 
    void Define (int a_number_of_grains, Set::Scalar a_alpha)
    {
        Define(a_number_of_grains, std::vector<Set::Scalar>(a_number_of_grains,a_alpha),Type::Partition);
    }
 
    void Define (int a_number_of_grains,
                std::vector<Set::Scalar> a_alpha,
                Type a_type = Type::Values)
    {
        number_of_grains = a_number_of_grains;
        alpha = a_alpha;
        type = a_type;
 
        if (a_alpha.size() == 1 && a_number_of_grains > 1)
            alpha.resize(a_number_of_grains,a_alpha[0]);
 
        voronoi.resize(number_of_grains);
        srand(seed);
        for (int n = 0; n<number_of_grains; n++)
        {
            AMREX_D_TERM(voronoi[n](0) = geom[0].ProbLo(0) + (geom[0].ProbHi(0)-geom[0].ProbLo(0))*Util::Random();,
                        voronoi[n](1) = geom[0].ProbLo(1) + (geom[0].ProbHi(1)-geom[0].ProbLo(1))*Util::Random();,
                        voronoi[n](2) = geom[0].ProbLo(2) + (geom[0].ProbHi(2)-geom[0].ProbLo(2))*Util::Random(););
        }
    };
    
    void Add(const int &lev, Set::Field<Set::Scalar> &a_field, Set::Scalar)
    {
        Set::Vector size;
        AMREX_D_TERM(size(0) = geom[0].ProbHi()[0] - geom[0].ProbLo()[0];,
                    size(1) = geom[0].ProbHi()[1] - geom[0].ProbLo()[1];,
                    size(2) = geom[0].ProbHi()[2] - geom[0].ProbLo()[2];)
 
        for (amrex::MFIter mfi(*a_field[lev],amrex::TilingIfNotGPU()); mfi.isValid(); ++mfi)
        {
            amrex::Box bx;
            amrex::IndexType ixtype = a_field[lev]->ixType();
            if (ixtype == amrex::IndexType::TheCellType())      bx = mfi.growntilebox();
            else if (ixtype == amrex::IndexType::TheNodeType()) bx = mfi.grownnodaltilebox();
 
            int ncomp = a_field[lev]->nComp();
            amrex::Array4<Set::Scalar> const& field = a_field[lev]->array(mfi);
            amrex::ParallelFor (bx,[=] AMREX_GPU_DEVICE(int i, int j, int k) {
 
                Set::Vector x;
                AMREX_D_TERM(x(0) = geom[lev].ProbLo()[0] + ((amrex::Real)(i) + 0.5) * geom[lev].CellSize()[0];,
                            x(1) = geom[lev].ProbLo()[1] + ((amrex::Real)(j) + 0.5) * geom[lev].CellSize()[1];,
                            x(2) = geom[lev].ProbLo()[2] + ((amrex::Real)(k) + 0.5) * geom[lev].CellSize()[2];);
                            
                amrex::Real min_distance = std::numeric_limits<amrex::Real>::infinity();
                int min_grain_id = -1;
 
                for (int n = 0; n<number_of_grains; n++)
                {
                    Set::Scalar d = (x - voronoi[n]).lpNorm<2>();
 
                    if (geom[0].isPeriodic(0))
                        {
                            d = std::min(d,
                                        std::min( (x-voronoi[n] + size(0)*Set::Vector::Unit(0)).lpNorm<2>(),
                                                    (x-voronoi[n] - size(0)*Set::Vector::Unit(0)).lpNorm<2>()));
                        }
#if AMREX_SPACEDIM>1
                    if (geom[0].isPeriodic(1))
                        {
                            d = std::min(d,
                                        std::min( (x-voronoi[n] + size(0)*Set::Vector::Unit(1)).lpNorm<2>(),
                                                    (x-voronoi[n] - size(0)*Set::Vector::Unit(1)).lpNorm<2>()));
                        }
#endif
#if AMREX_SPACEDIM>2
                    if (geom[0].isPeriodic(2))
                        {
                            d = std::min(d,
                                        std::min( (x-voronoi[n] + size(0)*Set::Vector::Unit(2)).lpNorm<2>(),
                                                    (x-voronoi[n] - size(0)*Set::Vector::Unit(2)).lpNorm<2>()));
                        }
#endif
                    if (d<min_distance)
                        {
                            min_distance = d;
                            min_grain_id = n;
                        }
                }
 
                if (type == Type::Values) field(i,j,k) = alpha[min_grain_id];
                else if (type == Type::Partition) field(i,j,k,min_grain_id % ncomp) = alpha[min_grain_id];
            });
        }
    }
 
    static void Parse(Voronoi &value, IO::ParmParse &pp)
    {
        pp.query("number_of_grains",value.number_of_grains); // Number of grains
        pp.queryarr_default("alpha",value.alpha,{1.0}); // value that the field should take in each grain
        pp.query("seed",value.seed); // Random seed to use
 
        // Determine initialization type. 
        // "Partition" splits the tesselation across components, with voronoi region "n" being set to alpha[n]
        // in field component n only.
        // "Values" combines all cells into a single component of the field.
        pp.query_switch("type",{
                {"partition",[&](){ value.type = Type::Partition; }},
                {"values",   [&](){ value.type = Type::Values;   }}
            });
 
        if (IO::ParmParse::InTraversalMode()) return;
 
        value.Define(value.number_of_grains,value.alpha,value.type);
    }
    
private:
    int number_of_grains;
    int seed = 1;
    std::vector<Set::Scalar> alpha;
    std::vector<Set::Vector> voronoi;
    Type type;
};
}
#endif