#ifndef _HITLIST_HXX
#define _HITLIST_HXX

#ifndef __cplusplus                                                          
# error This library requires C++
#endif                                   

#include <simgear/compiler.h>

#include <vector>

#include <plib/ssg.h>

SG_USING_STD(vector);


class FGHitRec {

private:
    ssgEntity *ent;
    int index;
    sgdVec3 point;
    sgdVec3 normal;

public:

    FGHitRec( ssgEntity *e, int idx, sgdVec3 p, sgdVec3 n ) {
	ent = e;
	index = idx;
	sgdSetVec3(point,p[0],p[1],p[2]);
	sgdSetVec3(normal,n[0],n[1],n[2]);
    }

    ssgEntity *get_entity(void) { return ent; }
    int get_face(void)          { return index; }
    double *get_point(void)     { return point; }
    double *get_normal(void)    { return normal; }
};


class FGHitList {

private:

    ssgEntity *last;
    vector < FGHitRec > list;

public:

    FGHitList() { last = NULL; }
    void init(void) { list.clear(); }
    void clear(void) { init(); last = NULL; }
    void add( ssgEntity *ent, int idx, sgdVec3 point, sgdVec3 normal ) {
	list.push_back( FGHitRec( ent,idx,point,normal) );
	last = ent;
    }
    int num_hits(void) { return list.size(); }
    ssgEntity *get_entity(int i)  { return list[i].get_entity(); }
    ssgEntity *last_hit(void)     { return last; }
    int get_face(int i)           { return list[i].get_face(); }
    double *get_point(int i)      { return list[i].get_point(); }
    double *get_normal(int i)     { return list[i].get_normal(); }
		
    void Intersect( ssgBranch *branch,
		    sgdVec3 orig, sgdVec3 dir );
		
    void IntersectBranch( ssgBranch *branch, sgdMat4 m,
			  sgdVec3 orig, sgdVec3 dir);
		
    void IntersectCachedLeaf( sgdMat4 m,
			      sgdVec3 orig, sgdVec3 dir);
		
    int IntersectLeaf( ssgLeaf *leaf, sgdMat4 m,
		       sgdVec3 orig, sgdVec3 dir );
};


inline void FGHitList::Intersect( ssgBranch *scene,
				  sgdVec3 orig, sgdVec3 dir )
{
    sgdMat4 m;

#ifdef USE_CACHED_HIT
	// This optimization gives a slight speedup
	// but it precludes using the hitlist for dynamic
	// objects  NHV
    init();
    if( last_hit() ) {
	sgdMakeIdentMat4 ( m ) ;
	IntersectCachedLeaf(m, orig, dir);
    }
    if( ! num_hits() ) {
#endif
	clear();
	sgdMakeIdentMat4 ( m ) ;
	IntersectBranch( scene, m, orig, dir);
#ifdef USE_CACHED_HIT
    }
#endif
}


// Associated function, assuming a wgs84 world with 0,0,0 at the
// center, find the current terrain intersection elevation for the
// point specified.
bool fgCurrentElev( sgdVec3 abs_view_pos, sgdVec3 scenery_center,
		    FGHitList *hit_list,
		    double *terrain_elev, double *radius, double *normal );


#endif // _HITLIST_HXX