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(svn r14502) -Codechange: add some inline comments and declare variable on use (Alberth)

release/0.7
rubidium 2008-10-20 15:44:14 +00:00
parent 9df75b3f9e
commit 6c35825453
1 changed files with 25 additions and 20 deletions
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45
src/tile_map.cpp
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@ -14,13 +14,6 @@
* @return Slope of the tile, except for the HALFTILE part */ * @return Slope of the tile, except for the HALFTILE part */
Slope GetTileSlope(TileIndex tile, uint *h) Slope GetTileSlope(TileIndex tile, uint *h)
{ {
uint a;
uint b;
uint c;
uint d;
uint min;
uint r;
assert(tile < MapSize()); assert(tile < MapSize());
if (TileX(tile) == MapMaxX() || TileY(tile) == MapMaxY()) { if (TileX(tile) == MapMaxX() || TileY(tile) == MapMaxY()) {
@ -28,15 +21,27 @@ Slope GetTileSlope(TileIndex tile, uint *h)
return SLOPE_FLAT; return SLOPE_FLAT;
} }
min = a = TileHeight(tile); uint a = TileHeight(tile); // Height of the N corner
b = TileHeight(tile + TileDiffXY(1, 0)); 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; 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; 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; 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 ((a -= min) != 0) r += (--a << 4) + SLOPE_N;
if ((c -= min) != 0) r += (--c << 4) + SLOPE_E; if ((c -= min) != 0) r += (--c << 4) + SLOPE_E;
if ((d -= min) != 0) r += (--d << 4) + SLOPE_S; 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; if (TileX(tile) == MapMaxX() || TileY(tile) == MapMaxY()) return 0;
uint h = TileHeight(tile); uint h = TileHeight(tile); // N corner
h = min(h, TileHeight(tile + TileDiffXY(1, 0))); h = min(h, TileHeight(tile + TileDiffXY(1, 0))); // W corner
h = min(h, TileHeight(tile + TileDiffXY(0, 1))); h = min(h, TileHeight(tile + TileDiffXY(0, 1))); // E corner
h = min(h, TileHeight(tile + TileDiffXY(1, 1))); h = min(h, TileHeight(tile + TileDiffXY(1, 1))); // S corner
return h * TILE_HEIGHT; return h * TILE_HEIGHT;
} }
@ -71,10 +76,10 @@ uint GetTileMaxZ(TileIndex t)
{ {
if (TileX(t) == MapMaxX() || TileY(t) == MapMaxY()) return 0; if (TileX(t) == MapMaxX() || TileY(t) == MapMaxY()) return 0;
uint h = TileHeight(t); uint h = TileHeight(t); // N corner
h = max(h, TileHeight(t + TileDiffXY(1, 0))); h = max(h, TileHeight(t + TileDiffXY(1, 0))); // W corner
h = max(h, TileHeight(t + TileDiffXY(0, 1))); h = max(h, TileHeight(t + TileDiffXY(0, 1))); // E corner
h = max(h, TileHeight(t + TileDiffXY(1, 1))); h = max(h, TileHeight(t + TileDiffXY(1, 1))); // S corner
return h * TILE_HEIGHT; return h * TILE_HEIGHT;
} }