diff options
| -rw-r--r-- | src/tile_map.cpp | 45 |
1 files changed, 25 insertions, 20 deletions
diff --git a/src/tile_map.cpp b/src/tile_map.cpp index 27b0a08a1..4f6ea17d6 100644 --- a/src/tile_map.cpp +++ b/src/tile_map.cpp @@ -14,13 +14,6 @@ * @return Slope of the tile, except for the HALFTILE part */ Slope GetTileSlope(TileIndex tile, uint *h) { - uint a; - uint b; - uint c; - uint d; - uint min; - uint r; - assert(tile < MapSize()); if (TileX(tile) == MapMaxX() || TileY(tile) == MapMaxY()) { @@ -28,15 +21,27 @@ Slope GetTileSlope(TileIndex tile, uint *h) return SLOPE_FLAT; } - min = a = TileHeight(tile); - b = TileHeight(tile + TileDiffXY(1, 0)); + uint a = TileHeight(tile); // Height of the N corner + uint min = a; // Minimal height of all corners examined so far + uint b = TileHeight(tile + TileDiffXY(1, 0)); // Height of the W corner if (min > b) min = b; - c = TileHeight(tile + TileDiffXY(0, 1)); + uint c = TileHeight(tile + TileDiffXY(0, 1)); // Height of the E corner if (min > c) min = c; - d = TileHeight(tile + TileDiffXY(1, 1)); + uint d = TileHeight(tile + TileDiffXY(1, 1)); // Height of the S corner if (min > d) min = d; - r = SLOPE_FLAT; + /* Due to the fact that tiles must connect with each other without leaving gaps, the + * biggest difference in height between any corner and 'min' is between 0, 1, or 2. + * + * Also, there is at most 1 corner with height difference of 2. + */ + + uint r = SLOPE_FLAT; // Computed slope of the tile + + /* For each corner if not equal to minimum height: + * - set the SLOPE_STEEP flag if the difference is 2 + * - add the corresponding SLOPE_X constant to the computed slope + */ if ((a -= min) != 0) r += (--a << 4) + SLOPE_N; if ((c -= min) != 0) r += (--c << 4) + SLOPE_E; if ((d -= min) != 0) r += (--d << 4) + SLOPE_S; @@ -55,10 +60,10 @@ uint GetTileZ(TileIndex tile) { if (TileX(tile) == MapMaxX() || TileY(tile) == MapMaxY()) return 0; - uint h = TileHeight(tile); - h = min(h, TileHeight(tile + TileDiffXY(1, 0))); - h = min(h, TileHeight(tile + TileDiffXY(0, 1))); - h = min(h, TileHeight(tile + TileDiffXY(1, 1))); + uint h = TileHeight(tile); // N corner + h = min(h, TileHeight(tile + TileDiffXY(1, 0))); // W corner + h = min(h, TileHeight(tile + TileDiffXY(0, 1))); // E corner + h = min(h, TileHeight(tile + TileDiffXY(1, 1))); // S corner return h * TILE_HEIGHT; } @@ -71,10 +76,10 @@ uint GetTileMaxZ(TileIndex t) { if (TileX(t) == MapMaxX() || TileY(t) == MapMaxY()) return 0; - uint h = TileHeight(t); - h = max(h, TileHeight(t + TileDiffXY(1, 0))); - h = max(h, TileHeight(t + TileDiffXY(0, 1))); - h = max(h, TileHeight(t + TileDiffXY(1, 1))); + uint h = TileHeight(t); // N corner + h = max(h, TileHeight(t + TileDiffXY(1, 0))); // W corner + h = max(h, TileHeight(t + TileDiffXY(0, 1))); // E corner + h = max(h, TileHeight(t + TileDiffXY(1, 1))); // S corner return h * TILE_HEIGHT; } |