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//
// Filename : HashGrid.h
// Author(s) : Stephane Grabli
// Purpose : Class to define a cell grid surrounding the
// bounding box of the scene
// Date of creation : 30/07/2002
//
///////////////////////////////////////////////////////////////////////////////
//
// Copyright (C) : Please refer to the COPYRIGHT file distributed
// with this source distribution.
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//
///////////////////////////////////////////////////////////////////////////////
#ifndef HASHGRID_H
# define HASHGRID_H
//# if defined(__GNUC__) && (__GNUC__ >= 3)
// hash_map is not part of the C++ standard anymore;
// hash_map.h has been kept though for backward compatibility
//# include <hash_map.h>
//# else
//# include <hash_map>
//# endif
# include "Grid.h"
# include <map>
/*! Defines a hash table used for searching the Cells */
struct GridHasher{
#define _MUL 950706376UL
#define _MOD 2147483647UL
inline size_t operator() (const Vec3u& p) const
{
size_t res = ((unsigned long) (p[0] * _MUL)) % _MOD;
res = ((res + (unsigned long) (p[1]) * _MUL)) % _MOD;
return ((res +(unsigned long) (p[2]) * _MUL)) % _MOD;
}
};
/*! Class to define a regular grid used for ray
casting computations */
class LIB_GEOMETRY_EXPORT HashGrid : public Grid
{
public:
typedef map<Vec3u, Cell*> GridHashTable;
HashGrid() : Grid() {}
virtual ~HashGrid() {
clear();
}
/*! clears the grid
* Deletes all the cells, clears the hashtable,
* resets size, size of cell, number of cells.
*/
virtual void clear();
/*! Sets the different parameters of the grid
* orig
* The grid origin
* size
* The grid's dimensions
* nb
* The number of cells of the grid
*/
virtual void configure(const Vec3r& orig, const Vec3r& size, unsigned nb);
/*! returns the cell whose coordinates
* are pased as argument
*/
virtual Cell* getCell(const Vec3u& p) {
Cell* found_cell = NULL;
GridHashTable::const_iterator found = _cells.find(p);
if (found != _cells.end())
found_cell = (*found).second;
return found_cell;
}
/*! Fills the case p with the cell iCell */
virtual void fillCell(const Vec3u& p, Cell& cell) {
_cells[p] = &cell;
}
protected:
GridHashTable _cells;
};
#endif // HASHGRID_H
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