src/tilearea.cpp

   1 /*
   2  * This file is part of OpenTTD.
   3  * 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.
   4  * 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.
   5  * 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/>.
   6  */
   7
   8 /** @file tilearea.cpp Handling of tile areas. */
   9
  10 #include "stdafx.h"
  11
  12 #include "tilearea_type.h"
  13
  14 #include "safeguards.h"
  15
  16 /**
  17  * Construct this tile area based on two points.
  18  * @param start the start of the area
  19  * @param end   the end of the area
  20  */
  21 OrthogonalTileArea::OrthogonalTileArea(TileIndex start, TileIndex end)
  22 {
  23         assert(start < MapSize());
  24         assert(end < MapSize());
  25
  26         uint sx = TileX(start);
  27         uint sy = TileY(start);
  28         uint ex = TileX(end);
  29         uint ey = TileY(end);
  30
  31         if (sx > ex) Swap(sx, ex);
  32         if (sy > ey) Swap(sy, ey);
  33
  34         this->tile = TileXY(sx, sy);
  35         this->w    = ex - sx + 1;
  36         this->h    = ey - sy + 1;
  37 }
  38
  39 /**
  40  * Add a single tile to a tile area; enlarge if needed.
  41  * @param to_add The tile to add
  42  */
  43 void OrthogonalTileArea::Add(TileIndex to_add)
  44 {
  45         if (this->tile == INVALID_TILE) {
  46                 this->tile = to_add;
  47                 this->w = 1;
  48                 this->h = 1;
  49                 return;
  50         }
  51
  52         uint sx = TileX(this->tile);
  53         uint sy = TileY(this->tile);
  54         uint ex = sx + this->w - 1;
  55         uint ey = sy + this->h - 1;
  56
  57         uint ax = TileX(to_add);
  58         uint ay = TileY(to_add);
  59
  60         sx = min(ax, sx);
  61         sy = min(ay, sy);
  62         ex = max(ax, ex);
  63         ey = max(ay, ey);
  64
  65         this->tile = TileXY(sx, sy);
  66         this->w    = ex - sx + 1;
  67         this->h    = ey - sy + 1;
  68 }
  69
  70 /**
  71  * Does this tile area intersect with another?
  72  * @param ta the other tile area to check against.
  73  * @return true if they intersect.
  74  */
  75 bool OrthogonalTileArea::Intersects(const OrthogonalTileArea &ta) const
  76 {
  77         if (ta.w == 0 || this->w == 0) return false;
  78
  79         assert(ta.w != 0 && ta.h != 0 && this->w != 0 && this->h != 0);
  80
  81         uint left1   = TileX(this->tile);
  82         uint top1    = TileY(this->tile);
  83         uint right1  = left1 + this->w - 1;
  84         uint bottom1 = top1  + this->h - 1;
  85
  86         uint left2   = TileX(ta.tile);
  87         uint top2    = TileY(ta.tile);
  88         uint right2  = left2 + ta.w - 1;
  89         uint bottom2 = top2  + ta.h - 1;
  90
  91         return !(
  92                         left2   > right1  ||
  93                         right2  < left1   ||
  94                         top2    > bottom1 ||
  95                         bottom2 < top1
  96                 );
  97 }
  98
  99 /**
 100  * Does this tile area contain a tile?
 101  * @param tile Tile to test for.
 102  * @return True if the tile is inside the area.
 103  */
 104 bool OrthogonalTileArea::Contains(TileIndex tile) const
 105 {
 106         if (this->w == 0) return false;
 107
 108         assert(this->w != 0 && this->h != 0);
 109
 110         uint left   = TileX(this->tile);
 111         uint top    = TileY(this->tile);
 112         uint tile_x = TileX(tile);
 113         uint tile_y = TileY(tile);
 114
 115         return IsInsideBS(tile_x, left, this->w) && IsInsideBS(tile_y, top, this->h);
 116 }
 117
 118 /**
 119  * Expand a tile area by rad tiles in each direction, keeping within map bounds.
 120  * @param rad Number of tiles to expand
 121  * @return The OrthogonalTileArea.
 122  */
 123 OrthogonalTileArea &OrthogonalTileArea::Expand(int rad)
 124 {
 125         int x = TileX(this->tile);
 126         int y = TileY(this->tile);
 127
 128         int sx = max(x - rad, 0);
 129         int sy = max(y - rad, 0);
 130         int ex = min(x + this->w + rad, MapSizeX());
 131         int ey = min(y + this->h + rad, MapSizeY());
 132
 133         this->tile = TileXY(sx, sy);
 134         this->w    = ex - sx;
 135         this->h    = ey - sy;
 136         return *this;
 137 }
 138
 139 /**
 140  * Clamp the tile area to map borders.
 141  */
 142 void OrthogonalTileArea::ClampToMap()
 143 {
 144         assert(this->tile < MapSize());
 145         this->w = min(this->w, MapSizeX() - TileX(this->tile));
 146         this->h = min(this->h, MapSizeY() - TileY(this->tile));
 147 }
 148
 149 /**
 150  * Create a diagonal tile area from two corners.
 151  * @param start First corner of the area.
 152  * @param end Second corner of the area.
 153  */
 154 DiagonalTileArea::DiagonalTileArea(TileIndex start, TileIndex end) : tile(start)
 155 {
 156         assert(start < MapSize());
 157         assert(end < MapSize());
 158
 159         /* Unfortunately we can't find a new base and make all a and b positive because
 160          * the new base might be a "flattened" corner where there actually is no single
 161          * tile. If we try anyway the result is either inaccurate ("one off" half of the
 162          * time) or the code gets much more complex;
 163          *
 164          * We also need to increment/decrement a and b here to have one-past-end semantics
 165          * for a and b, just the way the orthogonal tile area does it for w and h. */
 166
 167         this->a = TileY(end) + TileX(end) - TileY(start) - TileX(start);
 168         this->b = TileY(end) - TileX(end) - TileY(start) + TileX(start);
 169         if (this->a > 0) {
 170                 this->a++;
 171         } else {
 172                 this->a--;
 173         }
 174
 175         if (this->b > 0) {
 176                 this->b++;
 177         } else {
 178                 this->b--;
 179         }
 180 }
 181
 182 /**
 183  * Does this tile area contain a tile?
 184  * @param tile Tile to test for.
 185  * @return True if the tile is inside the area.
 186  */
 187 bool DiagonalTileArea::Contains(TileIndex tile) const
 188 {
 189         int a = TileY(tile) + TileX(tile);
 190         int b = TileY(tile) - TileX(tile);
 191
 192         int start_a = TileY(this->tile) + TileX(this->tile);
 193         int start_b = TileY(this->tile) - TileX(this->tile);
 194
 195         int end_a = start_a + this->a;
 196         int end_b = start_b + this->b;
 197
 198         /* Swap if necessary, preserving the "one past end" semantics. */
 199         if (start_a > end_a) {
 200                 int tmp = start_a;
 201                 start_a = end_a + 1;
 202                 end_a = tmp + 1;
 203         }
 204         if (start_b > end_b) {
 205                 int tmp = start_b;
 206                 start_b = end_b + 1;
 207                 end_b = tmp + 1;
 208         }
 209
 210         return (a >= start_a && a < end_a && b >= start_b && b < end_b);
 211 }
 212
 213 /**
 214  * Move ourselves to the next tile in the rectangle on the map.
 215  */
 216 TileIterator &DiagonalTileIterator::operator++()
 217 {
 218         assert(this->tile != INVALID_TILE);
 219
 220         /* Determine the next tile, while clipping at map borders */
 221         bool new_line = false;
 222         do {
 223                 /* Iterate using the rotated coordinates. */
 224                 if (this->a_max == 1 || this->a_max == -1) {
 225                         /* Special case: Every second column has zero length, skip them completely */
 226                         this->a_cur = 0;
 227                         if (this->b_max > 0) {
 228                                 this->b_cur = min(this->b_cur + 2, this->b_max);
 229                         } else {
 230                                 this->b_cur = max(this->b_cur - 2, this->b_max);
 231                         }
 232                 } else {
 233                         /* Every column has at least one tile to process */
 234                         if (this->a_max > 0) {
 235                                 this->a_cur += 2;
 236                                 new_line = this->a_cur >= this->a_max;
 237                         } else {
 238                                 this->a_cur -= 2;
 239                                 new_line = this->a_cur <= this->a_max;
 240                         }
 241                         if (new_line) {
 242                                 /* offset of initial a_cur: one tile in the same direction as a_max
 243                                  * every second line.
 244                                  */
 245                                 this->a_cur = abs(this->a_cur) % 2 ? 0 : (this->a_max > 0 ? 1 : -1);
 246
 247                                 if (this->b_max > 0) {
 248                                         ++this->b_cur;
 249                                 } else {
 250                                         --this->b_cur;
 251                                 }
 252                         }
 253                 }
 254
 255                 /* And convert the coordinates back once we've gone to the next tile. */
 256                 uint x = this->base_x + (this->a_cur - this->b_cur) / 2;
 257                 uint y = this->base_y + (this->b_cur + this->a_cur) / 2;
 258                 /* Prevent wrapping around the map's borders. */
 259                 this->tile = x >= MapSizeX() || y >= MapSizeY() ? INVALID_TILE : TileXY(x, y);
 260         } while (this->tile > MapSize() && this->b_max != this->b_cur);
 261
 262         if (this->b_max == this->b_cur) this->tile = INVALID_TILE;
 263         return *this;
 264 }