QuadGeom.cpp

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////////////////////////////////////////////////////////////////////////////////
//
//  File: QuadGeom.cpp
//
//  For more information, please see: http://www.nektar.info/
//
//  The MIT License
//
//  Copyright (c) 2006 Division of Applied Mathematics, Brown University (USA),
//  Department of Aeronautics, Imperial College London (UK), and Scientific
//  Computing and Imaging Institute, University of Utah (USA).
//
//  Permission is hereby granted, free of charge, to any person obtaining a
//  copy of this software and associated documentation files (the "Software"),
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//  Description:
//
//
////////////////////////////////////////////////////////////////////////////////
 
#include <LibUtilities/Foundations/Interp.h>
#include <SpatialDomains/QuadGeom.h>
 
#include <SpatialDomains/Curve.hpp>
#include <SpatialDomains/GeomFactors.h>
#include <SpatialDomains/SegGeom.h>
#include <StdRegions/StdQuadExp.h>
 
using namespace std;
 
namespace Nektar::SpatialDomains
{
 
QuadGeom::QuadGeom()
{
    m_shapeType = LibUtilities::eQuadrilateral;
}
 
QuadGeom::QuadGeom(const int id, const SegGeomSharedPtr edges[],
                   const CurveSharedPtr curve)
    : Geometry2D(edges[0]->GetVertex(0)->GetCoordim(), curve)
{
    int j;
 
    m_shapeType = LibUtilities::eQuadrilateral;
    m_globalID  = id;
 
    /// Copy the edge shared pointers.
    m_edges.insert(m_edges.begin(), edges, edges + QuadGeom::kNedges);
    m_eorient.resize(kNedges);
 
    for (j = 0; j < kNedges; ++j)
    {
        m_eorient[j] =
            SegGeom::GetEdgeOrientation(*edges[j], *edges[(j + 1) % kNedges]);
        m_verts.push_back(
            edges[j]->GetVertex(m_eorient[j] == StdRegions::eForwards ? 0 : 1));
    }
 
    for (j = 2; j < kNedges; ++j)
    {
        m_eorient[j] = m_eorient[j] == StdRegions::eBackwards
                           ? StdRegions::eForwards
                           : StdRegions::eBackwards;
    }
 
    m_coordim = edges[0]->GetVertex(0)->GetCoordim();
    ASSERTL0(m_coordim > 1, "Cannot call function with dim == 1");
}
 
QuadGeom::QuadGeom(const QuadGeom &in) : Geometry2D(in)
{
    // From Geometry
    m_shapeType = in.m_shapeType;
    m_globalID  = in.m_globalID;
 
    // From QuadGeom
    m_verts = in.m_verts;
    m_edges = in.m_edges;
    for (int i = 0; i < kNedges; i++)
    {
        m_eorient[i] = in.m_eorient[i];
    }
}
 
QuadGeom::~QuadGeom()
{
}
 
void QuadGeom::SetUpXmap()
{
    int order0 = max(m_edges[0]->GetXmap()->GetBasis(0)->GetNumModes(),
                     m_edges[2]->GetXmap()->GetBasis(0)->GetNumModes());
    int order1 = max(m_edges[1]->GetXmap()->GetBasis(0)->GetNumModes(),
                     m_edges[3]->GetXmap()->GetBasis(0)->GetNumModes());
 
    const LibUtilities::BasisKey B0(
        LibUtilities::eModified_A, order0,
        LibUtilities::PointsKey(order0 + 1,
                                LibUtilities::eGaussLobattoLegendre));
    const LibUtilities::BasisKey B1(
        LibUtilities::eModified_A, order1,
        LibUtilities::PointsKey(order1 + 1,
                                LibUtilities::eGaussLobattoLegendre));
 
    m_xmap = MemoryManager<StdRegions::StdQuadExp>::AllocateSharedPtr(B0, B1);
}
 
NekDouble QuadGeom::v_GetCoord(const int i,
                               const Array<OneD, const NekDouble> &Lcoord)
{
    ASSERTL1(m_state == ePtsFilled, "Geometry is not in physical space");
 
    Array<OneD, NekDouble> tmp(m_xmap->GetTotPoints());
    m_xmap->BwdTrans(m_coeffs[i], tmp);
 
    return m_xmap->PhysEvaluate(Lcoord, tmp);
}
 
StdRegions::Orientation QuadGeom::GetFaceOrientation(const QuadGeom &face1,
                                                     const QuadGeom &face2,
                                                     bool doRot, int dir,
                                                     NekDouble angle,
                                                     NekDouble tol)
{
    return GetFaceOrientation(face1.m_verts, face2.m_verts, doRot, dir, angle,
                              tol);
}
 
/**
 * Calculate the orientation of face2 to face1 (note this is
 * not face1 to face2!).
 */
StdRegions::Orientation QuadGeom::GetFaceOrientation(
    const PointGeomVector &face1, const PointGeomVector &face2, bool doRot,
    int dir, NekDouble angle, NekDouble tol)
{
    int i, j, vmap[4] = {-1, -1, -1, -1};
 
    if (doRot)
    {
        PointGeom rotPt;
 
        for (i = 0; i < 4; ++i)
        {
            rotPt.Rotate((*face1[i]), dir, angle);
            for (j = 0; j < 4; ++j)
            {
                if (rotPt.dist(*face2[j]) < tol)
                {
                    vmap[j] = i;
                    break;
                }
            }
        }
    }
    else
    {
 
        NekDouble x, y, z, x1, y1, z1, cx = 0.0, cy = 0.0, cz = 0.0;
 
        // For periodic faces, we calculate the vector between the centre
        // points of the two faces. (For connected faces this will be
        // zero). We can then use this to determine alignment later in the
        // algorithm.
        for (i = 0; i < 4; ++i)
        {
            cx += (*face2[i])(0) - (*face1[i])(0);
            cy += (*face2[i])(1) - (*face1[i])(1);
            cz += (*face2[i])(2) - (*face1[i])(2);
        }
        cx /= 4;
        cy /= 4;
        cz /= 4;
 
        // Now construct a mapping which takes us from the vertices of one
        // face to the other. That is, vertex j of face2 corresponds to
        // vertex vmap[j] of face1.
        for (i = 0; i < 4; ++i)
        {
            x = (*face1[i])(0);
            y = (*face1[i])(1);
            z = (*face1[i])(2);
            for (j = 0; j < 4; ++j)
            {
                x1 = (*face2[j])(0) - cx;
                y1 = (*face2[j])(1) - cy;
                z1 = (*face2[j])(2) - cz;
                if (sqrt((x1 - x) * (x1 - x) + (y1 - y) * (y1 - y) +
                         (z1 - z) * (z1 - z)) < 1e-8)
                {
                    vmap[j] = i;
                    break;
                }
            }
        }
    }
 
    // Use the mapping to determine the eight alignment options between
    // faces.
    if (vmap[1] == (vmap[0] + 1) % 4)
    {
        switch (vmap[0])
        {
            case 0:
                return StdRegions::eDir1FwdDir1_Dir2FwdDir2;
                break;
            case 1:
                return StdRegions::eDir1BwdDir2_Dir2FwdDir1;
                break;
            case 2:
                return StdRegions::eDir1BwdDir1_Dir2BwdDir2;
                break;
            case 3:
                return StdRegions::eDir1FwdDir2_Dir2BwdDir1;
                break;
        }
    }
    else
    {
        switch (vmap[0])
        {
            case 0:
                return StdRegions::eDir1FwdDir2_Dir2FwdDir1;
                break;
            case 1:
                return StdRegions::eDir1BwdDir1_Dir2FwdDir2;
                break;
            case 2:
                return StdRegions::eDir1BwdDir2_Dir2BwdDir1;
                break;
            case 3:
                return StdRegions::eDir1FwdDir1_Dir2BwdDir2;
                break;
        }
    }
 
    ASSERTL0(false, "unable to determine face orientation");
    return StdRegions::eDir1FwdDir1_Dir2FwdDir2;
}
 
/**
 * Set up GeoFac for this geometry using Coord quadrature distribution
 */
void QuadGeom::v_GenGeomFactors()
{
    if (!m_setupState)
    {
        QuadGeom::v_Setup();
    }
 
    if (m_geomFactorsState != ePtsFilled)
    {
        GeomType Gtype = eRegular;
 
        QuadGeom::v_FillGeom();
 
        // We will first check whether we have a regular or deformed
        // geometry. We will define regular as those cases where the
        // Jacobian and the metric terms of the derivative are constants
        // (i.e. not coordinate dependent)
 
        // Check to see if expansions are linear
        // If not linear => deformed geometry
        m_straightEdge = 1;
        if ((m_xmap->GetBasisNumModes(0) != 2) ||
            (m_xmap->GetBasisNumModes(1) != 2))
        {
            Gtype          = eDeformed;
            m_straightEdge = 0;
        }
 
        // For linear expansions, the mapping from standard to local
        // element is given by the relation:
        // x_i = 0.25 * [ ( x_i^A + x_i^B + x_i^C + x_i^D)       +
        //                (-x_i^A + x_i^B + x_i^C - x_i^D)*xi_1  +
        //                (-x_i^A - x_i^B + x_i^C + x_i^D)*xi_2  +
        //                ( x_i^A - x_i^B + x_i^C - x_i^D)*xi_1*xi_2 ]
        //
        // The jacobian of the transformation and the metric terms
        // dxi_i/dx_j, involve only terms of the form dx_i/dxi_j (both
        // for coordim == 2 or 3). Inspecting the formula above, it can
        // be appreciated that the derivatives dx_i/dxi_j will be
        // constant, if the coefficient of the non-linear term is zero.
        //
        // That is why for regular geometry, we require
        //
        //     x_i^A - x_i^B + x_i^C - x_i^D = 0
        //
        // or equivalently
        //
        //     x_i^A - x_i^B = x_i^D - x_i^C
        //
        // This corresponds to quadrilaterals which are paralellograms.
        m_manifold    = Array<OneD, int>(2);
        m_manifold[0] = 0;
        m_manifold[1] = 1;
        if (m_coordim == 3)
        {
            PointGeom e01, e21, norm;
            e01.Sub(*m_verts[0], *m_verts[1]);
            e21.Sub(*m_verts[3], *m_verts[1]);
            norm.Mult(e01, e21);
            int tmpi   = 0;
            double tmp = std::fabs(norm[0]);
            if (tmp < fabs(norm[1]))
            {
                tmp  = fabs(norm[1]);
                tmpi = 1;
            }
            if (tmp < fabs(norm[2]))
            {
                tmpi = 2;
            }
            m_manifold[0] = (tmpi + 1) % 3;
            m_manifold[1] = (tmpi + 2) % 3;
        }
 
        if (Gtype == eRegular)
        {
            Array<OneD, Array<OneD, NekDouble>> verts(m_verts.size());
            for (int i = 0; i < m_verts.size(); ++i)
            {
                verts[i] = Array<OneD, NekDouble>(3);
                m_verts[i]->GetCoords(verts[i]);
            }
            // a00 + a01 xi1 + a02 xi2 + a03 xi1 xi2
            // a10 + a11 xi1 + a12 xi2 + a03 xi1 xi2
            m_isoParameter = Array<OneD, Array<OneD, NekDouble>>(2);
            for (int i = 0; i < 2; i++)
            {
                unsigned int d    = m_manifold[i];
                m_isoParameter[i] = Array<OneD, NekDouble>(4, 0.);
                // Karniadakis, Sherwin 2005, Appendix D
                NekDouble A          = verts[0][d];
                NekDouble B          = verts[1][d];
                NekDouble D          = verts[2][d];
                NekDouble C          = verts[3][d];
                m_isoParameter[i][0] = 0.25 * (A + B + C + D);  // 1
                m_isoParameter[i][1] = 0.25 * (-A + B - C + D); // xi1
                m_isoParameter[i][2] = 0.25 * (-A - B + C + D); // xi2
                m_isoParameter[i][3] = 0.25 * (A - B - C + D);  // xi1*xi2
                NekDouble tmp =
                    fabs(m_isoParameter[i][1]) + fabs(m_isoParameter[i][2]);
                if (fabs(m_isoParameter[i][3]) >
                    tmp * NekConstants::kNekZeroTol)
                {
                    Gtype = eDeformed;
                }
            }
        }
 
        if (Gtype == eRegular)
        {
            v_CalculateInverseIsoParam();
        }
        else if (m_straightEdge)
        {
            PreSolveStraightEdge();
        }
 
        m_geomFactors = MemoryManager<GeomFactors>::AllocateSharedPtr(
            Gtype, m_coordim, m_xmap, m_coeffs);
        m_geomFactorsState = ePtsFilled;
    }
}
 
/**
 * Note verts and edges are listed according to anticlockwise
 * convention but points in _coeffs have to be in array format from
 * left to right.
 */
void QuadGeom::v_FillGeom()
{
    // check to see if geometry structure is already filled
    if (m_state != ePtsFilled)
    {
        int i, j, k;
        int nEdgeCoeffs;
 
        if (m_curve)
        {
            int npts     = m_curve->m_points.size();
            int nEdgePts = (int)sqrt(static_cast<NekDouble>(npts));
            Array<OneD, NekDouble> tmp(npts);
            Array<OneD, NekDouble> tmp2(m_xmap->GetTotPoints());
            LibUtilities::PointsKey curveKey(nEdgePts, m_curve->m_ptype);
 
            // Sanity checks:
            // - Curved faces should have square number of points;
            // - Each edge should have sqrt(npts) points.
            ASSERTL0(nEdgePts * nEdgePts == npts,
                     "NUMPOINTS should be a square number in"
                     " quadrilteral " +
                         boost::lexical_cast<string>(m_globalID));
 
            for (i = 0; i < kNedges; ++i)
            {
                ASSERTL0(m_edges[i]->GetXmap()->GetNcoeffs() == nEdgePts,
                         "Number of edge points does not correspond to "
                         "number of face points in quadrilateral " +
                             boost::lexical_cast<string>(m_globalID));
            }
 
            for (i = 0; i < m_coordim; ++i)
            {
                for (j = 0; j < npts; ++j)
                {
                    tmp[j] = (m_curve->m_points[j]->GetPtr())[i];
                }
 
                // Interpolate m_curve points to GLL points
                LibUtilities::Interp2D(curveKey, curveKey, tmp,
                                       m_xmap->GetBasis(0)->GetPointsKey(),
                                       m_xmap->GetBasis(1)->GetPointsKey(),
                                       tmp2);
 
                // Forwards transform to get coefficient space.
                m_xmap->FwdTrans(tmp2, m_coeffs[i]);
            }
        }
 
        // Now fill in edges.
        Array<OneD, unsigned int> mapArray;
        Array<OneD, int> signArray;
 
        for (i = 0; i < kNedges; i++)
        {
            m_edges[i]->FillGeom();
            m_xmap->GetTraceToElementMap(i, mapArray, signArray, m_eorient[i]);
 
            nEdgeCoeffs = m_edges[i]->GetXmap()->GetNcoeffs();
 
            for (j = 0; j < m_coordim; j++)
            {
                for (k = 0; k < nEdgeCoeffs; k++)
                {
                    m_coeffs[j][mapArray[k]] =
                        signArray[k] * (m_edges[i]->GetCoeffs(j))[k];
                }
            }
        }
 
        m_state = ePtsFilled;
    }
}
 
void QuadGeom::PreSolveStraightEdge()
{
    int i0, i1, j1, j2;
    if (fabs(m_isoParameter[0][3]) >= fabs(m_isoParameter[1][3]))
    {
        i0 = 0;
        i1 = 1;
    }
    else
    {
        i1 = 0;
        i0 = 1;
        m_straightEdge |= 2;
    }
    NekDouble gamma = m_isoParameter[i1][3] / m_isoParameter[i0][3];
    std::vector<NekDouble> c(3);
    for (int i = 0; i < 3; ++i)
    {
        c[i] = m_isoParameter[i1][i] - gamma * m_isoParameter[i0][i];
    }
    if (fabs(c[1]) >= fabs(c[2]))
    {
        j1 = 1;
        j2 = 2;
    }
    else
    {
        j1 = 2;
        j2 = 1;
        m_straightEdge |= 4;
    }
    NekDouble beta = c[j2] / c[j1];
    if (i0 == 1)
    {
        Vmath::Vcopy(4, m_isoParameter[1], 1, m_isoParameter[0], 1);
    }
    if (j1 == 2)
    {
        NekDouble temp        = m_isoParameter[0][j1];
        m_isoParameter[0][j1] = m_isoParameter[0][j2];
        m_isoParameter[0][j2] = temp;
    }
    m_isoParameter[0][2] -= m_isoParameter[0][1] * beta;
    m_isoParameter[1][0] = c[0];
    m_isoParameter[1][1] = 1. / c[j1];
    m_isoParameter[1][2] = beta;
    m_isoParameter[1][3] = gamma;
}
 
int QuadGeom::v_GetDir(const int i, [[maybe_unused]] const int j) const
{
    return i % 2;
}
 
void QuadGeom::v_Reset(CurveMap &curvedEdges, CurveMap &curvedFaces)
{
    Geometry::v_Reset(curvedEdges, curvedFaces);
    CurveMap::iterator it = curvedFaces.find(m_globalID);
 
    if (it != curvedFaces.end())
    {
        m_curve = it->second;
    }
 
    for (int i = 0; i < 4; ++i)
    {
        m_edges[i]->Reset(curvedEdges, curvedFaces);
    }
 
    SetUpXmap();
    SetUpCoeffs(m_xmap->GetNcoeffs());
}
 
void QuadGeom::v_Setup()
{
    if (!m_setupState)
    {
        for (int i = 0; i < 4; ++i)
        {
            m_edges[i]->Setup();
        }
        SetUpXmap();
        SetUpCoeffs(m_xmap->GetNcoeffs());
        m_setupState = true;
    }
}
 
} // namespace Nektar::SpatialDomains