HashGrid.h

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/* SPDX-FileCopyrightText: 2023 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */
 
#pragma once
 
#if 0
#  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
#endif
 
#include <map>
 
#include "Grid.h"
 
namespace Freestyle {
 
struct GridHasher {
#define _MUL 950706376UL
#define _MOD 2147483647UL
  inline size_t operator()(const Vec3u &p) const
  {
    size_t res = (ulong(p[0] * _MUL)) % _MOD;
    res = ((res + ulong(p[1]) * _MUL)) % _MOD;
    return ((res + ulong(p[2]) * _MUL)) % _MOD;
  }
#undef _MUL
#undef _MOD
};
 
class HashGrid : public Grid {
 public:
  typedef map<Vec3u, Cell *> GridHashTable;
 
  HashGrid() : Grid() {}
 
  virtual ~HashGrid()
  {
    clear();
  }
 
  virtual void clear();
 
  virtual void configure(const Vec3r &orig, const Vec3r &size, uint nb);
 
  virtual Cell *getCell(const Vec3u &p)
  {
    Cell *found_cell = nullptr;
 
    GridHashTable::const_iterator found = _cells.find(p);
    if (found != _cells.end()) {
      found_cell = (*found).second;
    }
    return found_cell;
  }
 
  virtual void fillCell(const Vec3u &p, Cell &cell)
  {
    _cells[p] = &cell;
  }
 
 protected:
  GridHashTable _cells;
};
 
} /* namespace Freestyle */