source/graphics/HeightMipmap.h

   1 /* Copyright (C) 2020 Wildfire Games.
   2  * This file is part of 0 A.D.
   3  *
   4  * 0 A.D. is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * 0 A.D. is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18
  19 /*
  20  * Describes ground using heightmap mipmaps
  21  * Used for camera movement
  22  */
  23
  24 #ifndef INCLUDED_HEIGHTMIPMAP
  25 #define INCLUDED_HEIGHTMIPMAP
  26
  27 #include <vector>
  28
  29 class Path;
  30 using VfsPath = Path;
  31
  32 struct SMipmap
  33 {
  34         SMipmap() : m_MapSize(0), m_Heightmap(0) { }
  35         SMipmap(size_t MapSize, u16* Heightmap) : m_MapSize(MapSize), m_Heightmap(Heightmap) { }
  36
  37         size_t m_MapSize;
  38         u16* m_Heightmap;
  39 };
  40
  41 class CHeightMipmap
  42 {
  43         NONCOPYABLE(CHeightMipmap);
  44 public:
  45
  46         CHeightMipmap();
  47         ~CHeightMipmap();
  48
  49         void Initialize(size_t mapSize, const u16* ptr);
  50         void ReleaseData();
  51
  52         // update the heightmap mipmaps
  53         void Update(const u16* ptr);
  54
  55         // update a section of the heightmap mipmaps
  56         // (coordinates are heightmap cells, inclusive of lower bounds,
  57         // exclusive of upper bounds)
  58         void Update(const u16* ptr, size_t left, size_t bottom, size_t right, size_t top);
  59
  60         float GetTrilinearGroundLevel(float x, float z, float radius) const;
  61
  62         void DumpToDisk(const VfsPath& path) const;
  63
  64 private:
  65
  66         // get bilinear filtered height from mipmap
  67         float BilinearFilter(const SMipmap &mipmap, float x, float z) const;
  68
  69         // update rectangle of the output mipmap by bilinear interpolating an input mipmap of exactly twice its size
  70         void HalfResizeUpdate(SMipmap &out_mipmap, size_t mapSize, const u16* ptr, size_t left, size_t bottom, size_t right, size_t top);
  71
  72         // update rectangle of the output mipmap by bilinear interpolating the input mipmap
  73         void BilinearUpdate(SMipmap &out_mipmap, size_t mapSize, const u16* ptr, size_t left, size_t bottom, size_t right, size_t top);
  74
  75         // size of this map in each direction
  76         size_t m_MapSize;
  77
  78         // mipmap list
  79         std::vector<SMipmap> m_Mipmap;
  80 };
  81
  82 #endif