src/tilearea.cpp

   1 /* $Id: tilearea.cpp 26289 2014-02-02 14:53:26Z fonsinchen $ */
   2
   3 /*
   4  * This file is part of OpenTTD.
   5  * OpenTTD 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, version 2.
   6  * OpenTTD 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.
   7  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
   8  */
   9
  10 /** @file tilearea.cpp Handling of tile areas. */
  11
  12 #include "stdafx.h"
  13
  14 #include "tilearea_type.h"
  15
  16 #include "safeguards.h"
  17
  18 /**
  19  * Construct this tile area based on two points.
  20  * @param start the start of the area
  21  * @param end   the end of the area
  22  */
  23 OrthogonalTileArea::OrthogonalTileArea(TileIndex start, TileIndex end)
  24 {
  25         assert(start < MapSize());
  26         assert(end < MapSize());
  27
  28         uint sx = TileX(start);
  29         uint sy = TileY(start);
  30         uint ex = TileX(end);
  31         uint ey = TileY(end);
  32
  33         if (sx > ex) Swap(sx, ex);
  34         if (sy > ey) Swap(sy, ey);
  35
  36         this->tile = TileXY(sx, sy);
  37         this->w    = ex - sx + 1;
  38         this->h    = ey - sy + 1;
  39 }
  40
  41 /**
  42  * Add a single tile to a tile area; enlarge if needed.
  43  * @param to_add The tile to add
  44  */
  45 void OrthogonalTileArea::Add(TileIndex to_add)
  46 {
  47         if (this->tile == INVALID_TILE) {
  48                 this->tile = to_add;
  49                 this->w = 1;
  50                 this->h = 1;
  51                 return;
  52         }
  53
  54         uint sx = TileX(this->tile);
  55         uint sy = TileY(this->tile);
  56         uint ex = sx + this->w - 1;
  57         uint ey = sy + this->h - 1;
  58
  59         uint ax = TileX(to_add);
  60         uint ay = TileY(to_add);
  61
  62         sx = min(ax, sx);
  63         sy = min(ay, sy);
  64         ex = max(ax, ex);
  65         ey = max(ay, ey);
  66
  67         this->tile = TileXY(sx, sy);
  68         this->w    = ex - sx + 1;
  69         this->h    = ey - sy + 1;
  70 }
  71
  72 /**
  73  * Does this tile area intersect with another?
  74  * @param ta the other tile area to check against.
  75  * @return true if they intersect.
  76  */
  77 bool OrthogonalTileArea::Intersects(const OrthogonalTileArea &ta) const
  78 {
  79         if (ta.w == 0 || this->w == 0) return false;
  80
  81         assert(ta.w != 0 && ta.h != 0 && this->w != 0 && this->h != 0);
  82
  83         uint left1   = TileX(this->tile);
  84         uint top1    = TileY(this->tile);
  85         uint right1  = left1 + this->w - 1;
  86         uint bottom1 = top1  + this->h - 1;
  87
  88         uint left2   = TileX(ta.tile);
  89         uint top2    = TileY(ta.tile);
  90         uint right2  = left2 + ta.w - 1;
  91         uint bottom2 = top2  + ta.h - 1;
  92
  93         return !(
  94                         left2   > right1  ||
  95                         right2  < left1   ||
  96                         top2    > bottom1 ||
  97                         bottom2 < top1
  98                 );
  99 }
 100
 101 /**
 102  * Does this tile area contain a tile?
 103  * @param tile Tile to test for.
 104  * @return True if the tile is inside the area.
 105  */
 106 bool OrthogonalTileArea::Contains(TileIndex tile) const
 107 {
 108         if (this->w == 0) return false;
 109
 110         assert(this->w != 0 && this->h != 0);
 111
 112         uint left   = TileX(this->tile);
 113         uint top    = TileY(this->tile);
 114         uint tile_x = TileX(tile);
 115         uint tile_y = TileY(tile);
 116
 117         return IsInsideBS(tile_x, left, this->w) && IsInsideBS(tile_y, top, this->h);
 118 }
 119
 120 /**
 121  * Clamp the tile area to map borders.
 122  */
 123 void OrthogonalTileArea::ClampToMap()
 124 {
 125         assert(this->tile < MapSize());
 126         this->w = min(this->w, MapSizeX() - TileX(this->tile));
 127         this->h = min(this->h, MapSizeY() - TileY(this->tile));
 128 }
 129
 130 /**
 131  * Create a diagonal tile area from two corners.
 132  * @param start First corner of the area.
 133  * @param end Second corner of the area.
 134  */
 135 DiagonalTileArea::DiagonalTileArea(TileIndex start, TileIndex end) : tile(start)
 136 {
 137         assert(start < MapSize());
 138         assert(end < MapSize());
 139
 140         /* Unfortunately we can't find a new base and make all a and b positive because
 141          * the new base might be a "flattened" corner where there actually is no single
 142          * tile. If we try anyway the result is either inaccurate ("one off" half of the
 143          * time) or the code gets much more complex;
 144          *
 145          * We also need to increment/decrement a and b here to have one-past-end semantics
 146          * for a and b, just the way the orthogonal tile area does it for w and h. */
 147
 148         this->a = TileY(end) + TileX(end) - TileY(start) - TileX(start);
 149         this->b = TileY(end) - TileX(end) - TileY(start) + TileX(start);
 150         if (this->a > 0) {
 151                 this->a++;
 152         } else {
 153                 this->a--;
 154         }
 155
 156         if (this->b > 0) {
 157                 this->b++;
 158         } else {
 159                 this->b--;
 160         }
 161 }
 162
 163 /**
 164  * Does this tile area contain a tile?
 165  * @param tile Tile to test for.
 166  * @return True if the tile is inside the area.
 167  */
 168 bool DiagonalTileArea::Contains(TileIndex tile) const
 169 {
 170         int a = TileY(tile) + TileX(tile);
 171         int b = TileY(tile) - TileX(tile);
 172
 173         int start_a = TileY(this->tile) + TileX(this->tile);
 174         int start_b = TileY(this->tile) - TileX(this->tile);
 175
 176         int end_a = start_a + this->a;
 177         int end_b = start_b + this->b;
 178
 179         /* Swap if necessary, preserving the "one past end" semantics. */
 180         if (start_a > end_a) {
 181                 int tmp = start_a;
 182                 start_a = end_a + 1;
 183                 end_a = tmp + 1;
 184         }
 185         if (start_b > end_b) {
 186                 int tmp = start_b;
 187                 start_b = end_b + 1;
 188                 end_b = tmp + 1;
 189         }
 190
 191         return (a >= start_a && a < end_a && b >= start_b && b < end_b);
 192 }
 193
 194 /**
 195  * Move ourselves to the next tile in the rectangle on the map.
 196  */
 197 TileIterator &DiagonalTileIterator::operator++()
 198 {
 199         assert(this->tile != INVALID_TILE);
 200
 201         /* Determine the next tile, while clipping at map borders */
 202         bool new_line = false;
 203         do {
 204                 /* Iterate using the rotated coordinates. */
 205                 if (this->a_max == 1 || this->a_max == -1) {
 206                         /* Special case: Every second column has zero length, skip them completely */
 207                         this->a_cur = 0;
 208                         if (this->b_max > 0) {
 209                                 this->b_cur = min(this->b_cur + 2, this->b_max);
 210                         } else {
 211                                 this->b_cur = max(this->b_cur - 2, this->b_max);
 212                         }
 213                 } else {
 214                         /* Every column has at least one tile to process */
 215                         if (this->a_max > 0) {
 216                                 this->a_cur += 2;
 217                                 new_line = this->a_cur >= this->a_max;
 218                         } else {
 219                                 this->a_cur -= 2;
 220                                 new_line = this->a_cur <= this->a_max;
 221                         }
 222                         if (new_line) {
 223                                 /* offset of initial a_cur: one tile in the same direction as a_max
 224                                  * every second line.
 225                                  */
 226                                 this->a_cur = abs(this->a_cur) % 2 ? 0 : (this->a_max > 0 ? 1 : -1);
 227
 228                                 if (this->b_max > 0) {
 229                                         ++this->b_cur;
 230                                 } else {
 231                                         --this->b_cur;
 232                                 }
 233                         }
 234                 }
 235
 236                 /* And convert the coordinates back once we've gone to the next tile. */
 237                 uint x = this->base_x + (this->a_cur - this->b_cur) / 2;
 238                 uint y = this->base_y + (this->b_cur + this->a_cur) / 2;
 239                 /* Prevent wrapping around the map's borders. */
 240                 this->tile = x >= MapSizeX() || y >= MapSizeY() ? INVALID_TILE : TileXY(x, y);
 241         } while (this->tile > MapSize() && this->b_max != this->b_cur);
 242
 243         if (this->b_max == this->b_cur) this->tile = INVALID_TILE;
 244         return *this;
 245 }