tilearea.cpp

Go to the documentation of this file.
00001 /* $Id$ */
00002 
00003 /*
00004  * This file is part of OpenTTD.
00005  * 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.
00006  * 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.
00007  * 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/>.
00008  */
00009 
00012 #include "stdafx.h"
00013 
00014 #include "tilearea_type.h"
00015 
00021 TileArea::TileArea(TileIndex start, TileIndex end)
00022 {
00023   uint sx = TileX(start);
00024   uint sy = TileY(start);
00025   uint ex = TileX(end);
00026   uint ey = TileY(end);
00027 
00028   if (sx > ex) Swap(sx, ex);
00029   if (sy > ey) Swap(sy, ey);
00030 
00031   this->tile = TileXY(sx, sy);
00032   this->w    = ex - sx + 1;
00033   this->h    = ey - sy + 1;
00034 }
00035 
00040 void TileArea::Add(TileIndex to_add)
00041 {
00042   if (this->tile == INVALID_TILE) {
00043     this->tile = to_add;
00044     this->w = 1;
00045     this->h = 1;
00046     return;
00047   }
00048 
00049   uint sx = TileX(this->tile);
00050   uint sy = TileY(this->tile);
00051   uint ex = sx + this->w - 1;
00052   uint ey = sy + this->h - 1;
00053 
00054   uint ax = TileX(to_add);
00055   uint ay = TileY(to_add);
00056 
00057   sx = min(ax, sx);
00058   sy = min(ay, sy);
00059   ex = max(ax, ex);
00060   ey = max(ay, ey);
00061 
00062   this->tile = TileXY(sx, sy);
00063   this->w    = ex - sx + 1;
00064   this->h    = ey - sy + 1;
00065 }
00066 
00072 bool TileArea::Intersects(const TileArea &ta) const
00073 {
00074   if (ta.w == 0 || this->w == 0) return false;
00075 
00076   assert(ta.w != 0 && ta.h != 0 && this->w != 0 && this->h != 0);
00077 
00078   uint left1   = TileX(this->tile);
00079   uint top1    = TileY(this->tile);
00080   uint right1  = left1 + this->w - 1;
00081   uint bottom1 = top1  + this->h - 1;
00082 
00083   uint left2   = TileX(ta.tile);
00084   uint top2    = TileY(ta.tile);
00085   uint right2  = left2 + ta.w - 1;
00086   uint bottom2 = top2  + ta.h - 1;
00087 
00088   return !(
00089       left2   > right1  ||
00090       right2  < left1   ||
00091       top2    > bottom1 ||
00092       bottom2 < top1
00093     );
00094 }
00095 
00099 void TileArea::ClampToMap()
00100 {
00101   assert(this->tile < MapSize());
00102   this->w = min(this->w, MapSizeX() - TileX(this->tile));
00103   this->h = min(this->h, MapSizeY() - TileY(this->tile));
00104 }
00105 
00111 DiagonalTileIterator::DiagonalTileIterator(TileIndex corner1, TileIndex corner2) : TileIterator(corner2), base_x(TileX(corner2)), base_y(TileY(corner2)), a_cur(0), b_cur(0)
00112 {
00113   assert(corner1 < MapSize());
00114   assert(corner2 < MapSize());
00115 
00116   int dist_x = TileX(corner1) - TileX(corner2);
00117   int dist_y = TileY(corner1) - TileY(corner2);
00118   this->a_max = dist_x + dist_y;
00119   this->b_max = dist_y - dist_x;
00120 
00121   /* Unfortunately we can't find a new base and make all a and b positive because
00122    * the new base might be a "flattened" corner where there actually is no single
00123    * tile. If we try anyway the result is either inaccurate ("one off" half of the
00124    * time) or the code gets much more complex;
00125    *
00126    * We also need to increment here to have equality as marker for the end of a row or
00127    * column. Like that it's shorter than having another if/else in operator++
00128    */
00129   if (this->a_max > 0) {
00130     this->a_max++;
00131   } else {
00132     this->a_max--;
00133   }
00134 
00135   if (this->b_max > 0) {
00136     this->b_max++;
00137   } else {
00138     this->b_max--;
00139   }
00140 }
00141 
00145 TileIterator &DiagonalTileIterator::operator++()
00146 {
00147   assert(this->tile != INVALID_TILE);
00148 
00149   /* Determine the next tile, while clipping at map borders */
00150   bool new_line = false;
00151   do {
00152     /* Iterate using the rotated coordinates. */
00153     if (this->a_max == 1 || this->a_max == -1) {
00154       /* Special case: Every second column has zero length, skip them completely */
00155       this->a_cur = 0;
00156       if (this->b_max > 0) {
00157         this->b_cur = min(this->b_cur + 2, this->b_max);
00158       } else {
00159         this->b_cur = max(this->b_cur - 2, this->b_max);
00160       }
00161     } else {
00162       /* Every column has at least one tile to process */
00163       if (this->a_max > 0) {
00164         this->a_cur += 2;
00165         new_line = this->a_cur >= this->a_max;
00166       } else {
00167         this->a_cur -= 2;
00168         new_line = this->a_cur <= this->a_max;
00169       }
00170       if (new_line) {
00171         /* offset of initial a_cur: one tile in the same direction as a_max
00172          * every second line.
00173          */
00174         this->a_cur = abs(this->a_cur) % 2 ? 0 : (this->a_max > 0 ? 1 : -1);
00175 
00176         if (this->b_max > 0) {
00177           ++this->b_cur;
00178         } else {
00179           --this->b_cur;
00180         }
00181       }
00182     }
00183 
00184     /* And convert the coordinates back once we've gone to the next tile. */
00185     uint x = this->base_x + (this->a_cur - this->b_cur) / 2;
00186     uint y = this->base_y + (this->b_cur + this->a_cur) / 2;
00187     /* Prevent wrapping around the map's borders. */
00188     this->tile = x >= MapSizeX() || y >= MapSizeY() ? INVALID_TILE : TileXY(x, y);
00189   } while (this->tile > MapSize() && this->b_max != this->b_cur);
00190 
00191   if (this->b_max == this->b_cur) this->tile = INVALID_TILE;
00192   return *this;
00193 }

Generated on Sun Jun 5 04:20:05 2011 for OpenTTD by  doxygen 1.6.1