Icosa.h

//
// Icosa.h
//
// Thanks go to Robert W. Gray (http://www.rwgrayprojects.com/) and the
// Buckminster Fuller Institute (http://www.bfi.org/) for notes, references,
// permission, and ancestral source for the following implementation.
//
// Copyright (c) 2001-2004 Virtual Terrain Project
// Free for all uses, see license.txt for details.
//

#ifndef ICOSAH
#define ICOSAH

#include "MathTypes.h"

struct icoface
{
    DPoint3 base;               // a designated "base corner" of each face
    DPoint3 center;             // the center of the face
    DPoint3 vec_a, vec_b, vec_c;    // normalized basis vectors

    DMatrix3 trans;

    double d;   // forth component of the plane equation
};

class DymaxIcosa
{
public:
    DymaxIcosa();

    void InitIcosa();

    void FindFaceUV(const DPoint2 &p, int &face, int &subface, DPoint3 &uvw);
    void FindFace(const DPoint3 &p, int &face, int &subface);
    void FindUV(const DPoint3 &p_in, int face, DPoint3 &uvw);

    void GeoToFacePoint(const DPoint2 &p, int &face, int &subface, DPoint3 &p_out);
    void FaceUVToGeo(int face, DPoint3 &uvw, double &lon, double &lat);
    bool GeoToDymax(const DPoint2 &geo, DPoint2 &dymax);

    double DihedralAngle();

    void GetDymaxEdges(DLine2Array &polys);

protected:
    void AddFlatTri(DLine2Array &polys, int a, int b, int c, int d=-1);

    // icosahedron data
    DPoint3 m_verts[12];
    icoface m_face[20];
    DPoint2 m_flatverts[27];
    double m_edge_length;   // edge length of icosahedron (~1.05 for unit radius)
};

// vertex indices for each face of the icosahedron
extern int icosa_face_v[20][3];
extern int icosa_face_pairs[10][2];

#endif  // ICOSAH