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(svn r21499) -Add: diagonal tile iterator. Based on patch by fonsinchen

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rubidium
2010-12-13 15:13:05 +00:00
parent 652e262601
commit b20e77be92
2 changed files with 84 additions and 1 deletions
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61
src/tilearea.cpp
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@@ -104,3 +104,64 @@ void TileArea::ClampToMap()
this->h = min(this->h, MapSizeY() - TileY(this->tile));
}
DiagonalTileIterator::DiagonalTileIterator(TileIndex corner1, TileIndex corner2) : TileIterator(corner2), base_x(TileX(corner2)), base_y(TileY(corner2)), a_cur(0), b_cur(0)
{
assert(corner1 < MapSize());
assert(corner2 < MapSize());
int dist_x = TileX(corner1) - TileX(corner2);
int dist_y = TileY(corner1) - TileY(corner2);
this->a_max = dist_x + dist_y;
this->b_max = dist_y - dist_x;
/* Unfortunately we can't find a new base and make all a and b positive because
* the new base might be a "flattened" corner where there actually is no single
* tile. If we try anyway the result is either inaccurate ("one off" half of the
* time) or the code gets much more complex;
*
* We also need to increment here to have equality as marker for the end of a row or
* column. Like that it's shorter than having another if/else in operator++
*/
if (this->a_max > 0) {
this->a_max++;
} else {
this->a_max--;
}
if (this->b_max > 0) {
this->b_max++;
} else {
this->b_max--;
}
}
TileIterator &DiagonalTileIterator::operator++()
{
assert(this->tile != INVALID_TILE);
do {
/* Iterate using the rotated coordinates. */
if (this->a_max > 0) {
++this->a_cur;
} else {
--this->a_cur;
}
if (this->a_cur == this->a_max) {
this->a_cur = 0;
if (this->b_max > 0) {
++this->b_cur;
} else {
--this->b_cur;
}
}
/* And convert the coordinates back once we've gone to the next tile. */
uint x = this->base_x + (this->a_cur - this->b_cur) / 2;
uint y = this->base_y + (this->b_cur + this->a_cur) / 2;
/* Prevent wrapping around the map's borders. */
this->tile = x >= MapSizeX() || y >= MapSizeY() ? INVALID_TILE : TileXY(x, y);
} while (this->tile > MapSize() && this->b_max != this->b_cur);
if (this->b_max == this->b_cur) this->tile = INVALID_TILE;
return *this;
}