mirror of https://github.com/OpenTTD/OpenTTD.git
(svn r26868) -Add: methods for getting a (theoretical) slope and tile height of tiles outside of the map array (ic111)
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src/tile_map.cpp
184
src/tile_map.cpp
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@ -15,7 +15,99 @@
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#include "safeguards.h"
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/**
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* Return the slope of a given tile
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* Returns the tile height for a coordinate outside map. Such a height is
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* needed for painting the area outside map using completely black tiles.
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* The idea is descending to heightlevel 0 as fast as possible.
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* @param x The X-coordinate (same unit as TileX).
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* @param y The Y-coordinate (same unit as TileY).
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* @return The height in the same unit as TileHeight.
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*/
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uint TileHeightOutsideMap(int x, int y)
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{
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/* In all cases: Descend to heightlevel 0 as fast as possible.
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* So: If we are at the 0-side of the map (x<0 or y<0), we must
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* subtract the distance to coordinate 0 from the heightlevel at
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* coordinate 0.
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* In other words: Subtract e.g. -x. If we are at the MapMax
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* side of the map, we also need to subtract the distance to
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* the edge of map, e.g. MapMaxX - x.
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*
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* NOTE: Assuming constant heightlevel outside map would be
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* simpler here. However, then we run into painting problems,
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* since whenever a heightlevel change at the map border occurs,
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* we would need to repaint anything outside map.
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* In contrast, by doing it this way, we can localize this change,
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* which means we may assume constant heightlevel for all tiles
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* at more than <heightlevel at map border> distance from the
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* map border.
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*/
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if (x < 0) {
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if (y < 0) {
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return max((int)TileHeight(TileXY(0, 0)) - (-x) - (-y), 0);
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} else if (y < (int)MapMaxY()) {
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return max((int)TileHeight(TileXY(0, y)) - (-x), 0);
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} else {
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return max((int)TileHeight(TileXY(0, (int)MapMaxY())) - (-x) - (y - (int)MapMaxY()), 0);
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}
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} else if (x < (int)MapMaxX()) {
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if (y < 0) {
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return max((int)TileHeight(TileXY(x, 0)) - (-y), 0);
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} else if (y < (int)MapMaxY()) {
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return TileHeight(TileXY(x, y));
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} else {
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return max((int)TileHeight(TileXY(x, (int)MapMaxY())) - (y - (int)MapMaxY()), 0);
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}
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} else {
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if (y < 0) {
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return max((int)TileHeight(TileXY((int)MapMaxX(), 0)) - (x - (int)MapMaxX()) - (-y), 0);
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} else if (y < (int)MapMaxY()) {
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return max((int)TileHeight(TileXY((int)MapMaxX(), y)) - (x - (int)MapMaxX()), 0);
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} else {
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return max((int)TileHeight(TileXY((int)MapMaxX(), (int)MapMaxY())) - (x - (int)MapMaxX()) - (y - (int)MapMaxY()), 0);
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}
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}
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}
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/**
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* Get a tile's slope given the heigh of its four corners.
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* @param hnorth The height at the northern corner in the same unit as TileHeight.
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* @param hwest The height at the western corner in the same unit as TileHeight.
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* @param heast The height at the eastern corner in the same unit as TileHeight.
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* @param hsouth The height at the southern corner in the same unit as TileHeight.
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* @param [out] h The lowest height of the four corners.
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* @return The slope.
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*/
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static Slope GetTileSlopeGivenHeight(int hnorth, int hwest, int heast, int hsouth, int *h)
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{
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/* Due to the fact that tiles must connect with each other without leaving gaps, the
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* biggest difference in height between any corner and 'min' is between 0, 1, or 2.
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*
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* Also, there is at most 1 corner with height difference of 2.
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*/
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int hminnw = min(hnorth, hwest);
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int hmines = min(heast, hsouth);
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int hmin = min(hminnw, hmines);
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if (h != NULL) *h = hmin;
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int hmaxnw = max(hnorth, hwest);
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int hmaxes = max(heast, hsouth);
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int hmax = max(hmaxnw, hmaxes);
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Slope r = SLOPE_FLAT;
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if (hnorth != hmin) r |= SLOPE_N;
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if (hwest != hmin) r |= SLOPE_W;
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if (heast != hmin) r |= SLOPE_E;
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if (hsouth != hmin) r |= SLOPE_S;
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if (hmax - hmin == 2) r |= SLOPE_STEEP;
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return r;
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}
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/**
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* Return the slope of a given tile inside the map.
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* @param tile Tile to compute slope of
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* @param h If not \c NULL, pointer to storage of z height
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* @return Slope of the tile, except for the HALFTILE part
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@ -29,35 +121,31 @@ Slope GetTileSlope(TileIndex tile, int *h)
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return SLOPE_FLAT;
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}
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int a = TileHeight(tile); // Height of the N corner
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int min = a; // Minimal height of all corners examined so far
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int b = TileHeight(tile + TileDiffXY(1, 0)); // Height of the W corner
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if (min > b) min = b;
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int c = TileHeight(tile + TileDiffXY(0, 1)); // Height of the E corner
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if (min > c) min = c;
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int d = TileHeight(tile + TileDiffXY(1, 1)); // Height of the S corner
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if (min > d) min = d;
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int hnorth = TileHeight(tile); // Height of the North corner.
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int hwest = TileHeight(tile + TileDiffXY(1, 0)); // Height of the West corner.
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int heast = TileHeight(tile + TileDiffXY(0, 1)); // Height of the East corner.
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int hsouth = TileHeight(tile + TileDiffXY(1, 1)); // Height of the South corner.
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/* Due to the fact that tiles must connect with each other without leaving gaps, the
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* biggest difference in height between any corner and 'min' is between 0, 1, or 2.
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*
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* Also, there is at most 1 corner with height difference of 2.
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*/
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return GetTileSlopeGivenHeight(hnorth, hwest, heast, hsouth, h);
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}
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uint r = SLOPE_FLAT; // Computed slope of the tile
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/**
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* Return the slope of a given tile outside the map.
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*
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* @param tile Tile outside the map to compute slope of.
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* @param h If not \c NULL, pointer to storage of z height.
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* @return Slope of the tile outside map, except for the HALFTILE part.
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*/
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Slope GetTilePixelSlopeOutsideMap(int x, int y, int *h)
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{
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int hnorth = TileHeightOutsideMap(x, y); // N corner.
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int hwest = TileHeightOutsideMap(x + 1, y); // W corner.
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int heast = TileHeightOutsideMap(x, y + 1); // E corner.
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int hsouth = TileHeightOutsideMap(x + 1, y + 1); // S corner.
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/* For each corner if not equal to minimum height:
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* - set the SLOPE_STEEP flag if the difference is 2
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* - add the corresponding SLOPE_X constant to the computed slope
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*/
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if ((a -= min) != 0) r += (--a << 4) + SLOPE_N;
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if ((c -= min) != 0) r += (--c << 4) + SLOPE_E;
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if ((d -= min) != 0) r += (--d << 4) + SLOPE_S;
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if ((b -= min) != 0) r += (--b << 4) + SLOPE_W;
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if (h != NULL) *h = min;
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return (Slope)r;
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Slope s = GetTileSlopeGivenHeight(hnorth, hwest, heast, hsouth, h);
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if (h != NULL) *h *= TILE_HEIGHT;
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return s;
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}
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/**
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@ -93,7 +181,7 @@ int GetTileZ(TileIndex tile)
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{
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if (TileX(tile) == MapMaxX() || TileY(tile) == MapMaxY()) return 0;
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int h = TileHeight(tile); // N corner
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int h = TileHeight(tile); // N corner
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h = min(h, TileHeight(tile + TileDiffXY(1, 0))); // W corner
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h = min(h, TileHeight(tile + TileDiffXY(0, 1))); // E corner
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h = min(h, TileHeight(tile + TileDiffXY(1, 1))); // S corner
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@ -102,18 +190,52 @@ int GetTileZ(TileIndex tile)
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}
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/**
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* Get top height of the tile
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* Get bottom height of the tile outside map.
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*
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* @param tile Tile outside the map to compute height of.
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* @return Minimum height of the tile outside the map.
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*/
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int GetTilePixelZOutsideMap(int x, int y)
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{
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uint h = TileHeightOutsideMap(x, y); // N corner.
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h = min(h, TileHeightOutsideMap(x + 1, y)); // W corner.
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h = min(h, TileHeightOutsideMap(x, y + 1)); // E corner.
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h = min(h, TileHeightOutsideMap(x + 1, y + 1)); // S corner
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return h * TILE_HEIGHT;
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}
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/**
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* Get top height of the tile inside the map.
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* @param t Tile to compute height of
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* @return Maximum height of the tile
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*/
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int GetTileMaxZ(TileIndex t)
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{
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if (TileX(t) == MapMaxX() || TileY(t) == MapMaxY()) return 0;
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if (TileX(t) == MapMaxX() || TileY(t) == MapMaxY()) return TileHeightOutsideMap(TileX(t), TileY(t));
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int h = TileHeight(t); // N corner
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int h = TileHeight(t); // N corner
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h = max<int>(h, TileHeight(t + TileDiffXY(1, 0))); // W corner
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h = max<int>(h, TileHeight(t + TileDiffXY(0, 1))); // E corner
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h = max<int>(h, TileHeight(t + TileDiffXY(1, 1))); // S corner
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return h;
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}
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/**
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* Get top height of the tile outside the map.
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*
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* @see Detailed description in header.
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*
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* @param tile Tile outside to compute height of.
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* @return Maximum height of the tile.
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*/
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int GetTileMaxPixelZOutsideMap(int x, int y)
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{
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uint h = TileHeightOutsideMap(x, y);
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h = max(h, TileHeightOutsideMap(x + 1, y));
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h = max(h, TileHeightOutsideMap(x, y + 1));
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h = max(h, TileHeightOutsideMap(x + 1, y + 1));
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return h * TILE_HEIGHT;
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}
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@ -34,6 +34,8 @@ static inline uint TileHeight(TileIndex tile)
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return GB(_m[tile].type_height, 0, 4);
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}
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uint TileHeightOutsideMap(int x, int y);
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/**
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* Sets the height of a tile.
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*
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@ -262,6 +264,8 @@ static inline Slope GetTilePixelSlope(TileIndex tile, int *h)
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return s;
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}
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Slope GetTilePixelSlopeOutsideMap(int x, int y, int *h);
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/**
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* Get bottom height of the tile
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* @param tile Tile to compute height of
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@ -272,6 +276,8 @@ static inline int GetTilePixelZ(TileIndex tile)
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return GetTileZ(tile) * TILE_HEIGHT;
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}
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int GetTilePixelZOutsideMap(int x, int y);
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/**
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* Get top height of the tile
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* @param t Tile to compute height of
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@ -282,6 +288,8 @@ static inline int GetTileMaxPixelZ(TileIndex tile)
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return GetTileMaxZ(tile) * TILE_HEIGHT;
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}
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int GetTileMaxPixelZOutsideMap(int x, int y);
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/**
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* Calculate a hash value from a tile position
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