#ifndef HEIGHTFIELD_H
#define HEIGHTFIELD_H
#include "shapes.h"

#define TILED 1
#define MINMAX 1

#ifdef TILED
#define TBITS 3
#define TMASK ((1<<TBITS)-1)
#define NMASK (~TMASK)
#define Z(x,y)							\
	z[((x)&TMASK) +						\
	  ((((y)&TMASK)+((x)&xmask))<<TBITS) +			\
	  (((y)&ymask)*(nxgrid&xmask))]
#ifdef MINMAX
#define ZMM(x,y)						\
	zmm[((x)&TMASK) +					\
	  ((((y)&TMASK)+((x)&xmask))<<TBITS) +			\
	  (((y)&ymask)*(nxgrid&xmask))]
#endif
#else
#define Z(x,y) z[(x&xmask) + nxgrid*(y&ymask)]
#ifdef MINMAX
#define ZMM(x,y) zmm[(x&xmask) + nxgrid*(y&ymask)]
#endif
#endif

#ifdef MINMAX
#define ZMIN(x,y,index) Z(x+(index&1),y+((index>>1)&1))
#define ZMAX(x,y,index) Z(x+((index>>2)&1),y+((index>>3)&1))
#endif

class Heightfield : public Shape {
public:
	Heightfield(const Transform &o2w, int xcount, int xrepeat,
			int ycount, int yrepeat, Float *zs);
	~Heightfield();
	BBox Bound() const;
	BBox BoundWorldSpace() const;
	bool Intersect(const Ray &ray, DifferentialGeometry *dg) const;
	bool IntersectP(const Ray &ray) const;
private:
	Normal VertNorm(int x, int y) const;
	Normal TriNorm(int x0, int y0, int x1, int y1, int x2, int y2) const;
	bool TestQuad(const Ray &ray, const Ray &oray,
		DifferentialGeometry *dg, int X, int Y) const;
	bool SetDG(const Ray &ray, DifferentialGeometry *dg,
		const Vector &edge,
		int X, int Y, int tri, Float u, Float v, Float t) const;
	Float *z;		// heightfield values
	char *zmm;		// packed index to min and max z values
	int nxgrid, nygrid;	// heightfield dataset dimensions
	int nxcell, nycell;	// heightfield dataset cells
	int nxfullgrid, nyfullgrid;	// heightfield replicated grid extent
	int nxfullcell, nyfullcell;	// heightfield replicated cell extent
	int xmask, ymask;	// mask used in address calculations
	Float zmin, zmax;	// heightfield min and max values
	BBox *bbox;		// bounding box structure
};

#endif