TVTerrain.h

//
// TVTerrain class : Dynamically rendering terrain
//
// Original authors: Will Evans and Gregg Townsend of the University of Arizona
//
// Copyright (c) 2001-2011 Virtual Terrain Project
// Free for all uses, see license.txt for details.
//

#ifndef TVTERRAINH
#define TVTERRAINH


#include <limits.h>
#include "DynTerrain.h"

/*
 * =========== Common Constants =============
 */
#ifndef PI
#define PI 3.1415926535897932385
#endif

/*
 * =========== Common Macros =============
 */
#ifndef ABS
#define ABS(x) (((x)<0)?(-(x)):(x))
#endif

#ifndef ROUND
#define ROUND(a) ((int)((a)+0.5))
#endif

/*
 * ============ Common Structures ============
 */

typedef int Coord2d[2];

/*
 * ============== Heirarchy ===============
 */
#define MAXERR USHRT_MAX    /* maximum scaled triangle error */

/* triangle info flag bits */
#define SMALLER1      1 /* Is neighbor 1 smaller? */
#define SMALLER2      2 /* Is neighbor 2 smaller? */
#define BIGGER3       4 /* Is neighbor 3 larger? */
#define SURFACE       8 /* on surface? */
#define ALLINFOV     16 /* completely in field of view? */
#define PARTINFOV    32 /* partially in field of view? */
#define ALLINROD     64 /* completely in rectangle of definition? */
#define PARTINROD   128 /* partially in rectangle of definition? */

/* info field access macros */
#define BORDER(t) (m_info[(t)->s] & PARTINROD)
#define INROD(t) (m_info[(t)->s] & ALLINROD)
#define PUTONSURFACE(t) \
    m_info[(t)->s] = (m_info[(t)->s]&(ALLINROD|PARTINROD))|SURFACE
#define ONSURFACE(t) (m_info[(t)->s] & SURFACE)
#define INFOV(t) (m_info[(t)->s] & (ALLINFOV | PARTINFOV))
#define SMALLN1(t) (m_info[(t)->s] & SMALLER1)
#define SMALLN2(t) (m_info[(t)->s] & SMALLER2)
#define BIGN3(t) (m_info[(t)->s] & BIGGER3)

/* these macros also take TriIndex arguments */
#define ISLEAF(t) ((t)->depth >= m_depth)
#define IAMLEFTCHILD(t) ((((t)->depth&1)&&(((t)->orient^(t)->x)&1)) || \
             ((((t)->depth&1)==0)&&(((t)->orient^(t)->x^(t)->y)&1)))
#define TRIEQUATE(a,b)  (a)->x=(b)->x; \
            (a)->y=(b)->y; \
            (a)->depth=(b)->depth; \
            (a)->orient=(b)->orient; \
            (a)->s=(b)->s

typedef struct {    /* triangle index */
  int x,y;          /* coords of square containing tri at depth */
  int depth;        /* depth of triangle */
  int orient;       /* orientation */
  int s;            /* physical address */
} TriIndex;

/* initial values */
#define IERRTHRESH      0.001
#define IERRTHRESHINC   0.00005
#define IDISTTHRESH     700.0
#define IDISTTHRESHINC  50.0
#define IVEXAGGER       1.0
#define IVEXAGGERINC    0.1


class TVTerrain : public vtDynTerrainGeom
{
public:
    TVTerrain();

    DTErr Init(const vtElevationGrid *pGrid, float fZScale);
    static int MemoryRequired(int iDimension);

    // overrides
    void DoRender();
    void DoCulling(const vtCamera *pCam);
    float GetElevation(int iX, int iZ, bool bTrue = false) const;
    void GetWorldLocation(int iX, int iZ, FPoint3 &p, bool bTrue = false) const;
    virtual float GetVerticalExag() const { return m_fZScale; }

protected:
    void mkscale(const vtElevationGrid *pGrid);
    int calcErr(const vtElevationGrid *pGrid, Coord2d p1, Coord2d p2, Coord2d p3);
    int inFOV(Coord2d p1, Coord2d p2, Coord2d p3);
    int triInFOV(TriIndex *t);
    int inROD(Coord2d p1, Coord2d p2, Coord2d p3);
    void makeDFS(const vtElevationGrid *pGrid, TriIndex *t, Coord2d p1, Coord2d p2, Coord2d p3);
    int init_ntriabove(int depth);
    void getVerts(TriIndex *t, Coord2d p1, Coord2d p2, Coord2d p3);

    void parent(TriIndex *t, TriIndex *p);
    void bro1(TriIndex *t, TriIndex *b1);
    void bro2(TriIndex *t, TriIndex *b2);
    void bro3(TriIndex *t, TriIndex *b3);
    void nbr1(TriIndex *t, TriIndex *n1);
    void nbr2(TriIndex *t, TriIndex *n2);
    void nbr3(TriIndex *t, TriIndex *n3);
    void kidsOnSurf(TriIndex *t);
    void split(TriIndex *t);
    void rodSplit(TriIndex *t);
    void eyeSplit(TriIndex *t, Coord2d p1, Coord2d p2, Coord2d p3);
    void baseSurface();

    int tooCoarse(TriIndex *t, Coord2d p1, Coord2d p2, Coord2d p3);
    void errSplit(TriIndex *t, Coord2d p1, Coord2d p2, Coord2d p3);
    void errSurface();
    void buildSurface(FPoint3 &eyepos_ogl);
    void emitSurface();
    void emitDFS(TriIndex *t, Coord2d p1, Coord2d p2, Coord2d p3);
    void emitTri(TriIndex *t, Coord2d p1, Coord2d p2, Coord2d p3);
    void getNormal(int,int,double,int,int,double,int,int,double,double*,double*,double*);

protected:
    // cleanup
    virtual ~TVTerrain();

private:
    float   m_fXScale, m_fYScale, m_fZScale;

/* heirarchy data */
    int m_depth;            /* maximum depth */
    int m_size;             /* number of triangles in hierarchy */
    int m_numSurfTri;       /* number of triangles on surface */
    unsigned short *m_err;  /* error of triangles */
    uchar *m_info;  /* surface,neighbor,infov of triangles */
    int m_iLevels;

    double x_per_y, y_per_x, errPerEm;

/* terrain data */
    float *m_pVertex;

    double xmeters, ymeters;    /* dimensions of data in meters */
    double xscale, yscale;      /* scales grid distance to meters */
    double m2grid;              /* scales vertical meters to grid units */
    double err2grid;            /* scales 0..MAXERR to grid units */
    Coord2d se, sw, ne, nw;
    TriIndex rootL, rootR;      /* initial Triangles */

/* Triangle err/distance from eye must be < errThresh */
    double errThresh;

/* Triangles < k*distThresh meters from eye must have size < 2^k */
    double distThresh;

/* error parameters, derived from errThresh (above) */
    double etGrid, dtGrid;

/* current viewpoint */
    double eyeEmx, eyeEmy, eyeEmz;  /* eye location */
    int numDisplayTri;      /* number of displayed triangles */

// quick conversion from x,y index to output X,Y coordinates
//  float   *fXLookup, *fYLookup;

    Coord2d eyeP;
};
    // Group dynterr

#endif  // TVTERRAINH