src/slope_func.h

   1 /* $Id$ */
   2
   3 /*
   4  * This file is part of OpenTTD.
   5  * 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.
   6  * 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.
   7  * 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/>.
   8  */
   9
  10 /** @file slope_func.h Functions related to slopes. */
  11
  12 #ifndef SLOPE_FUNC_H
  13 #define SLOPE_FUNC_H
  14
  15 #include "core/math_func.hpp"
  16 #include "slope_type.h"
  17 #include "direction_type.h"
  18 #include "tile_type.h"
  19
  20 /**
  21  * Rangecheck for Corner enumeration.
  22  *
  23  * @param corner A #Corner.
  24  * @return true iff corner is in a valid range.
  25  */
  26 static inline bool IsValidCorner(Corner corner)
  27 {
  28         return IsInsideMM(corner, 0, CORNER_END);
  29 }
  30
  31
  32 /**
  33  * Checks if a slope is steep.
  34  *
  35  * @param s The given #Slope.
  36  * @return True if the slope is steep, else false.
  37  */
  38 static inline bool IsSteepSlope(Slope s)
  39 {
  40         return (s & SLOPE_STEEP) != 0;
  41 }
  42
  43 /**
  44  * Checks for non-continuous slope on halftile foundations.
  45  *
  46  * @param s The given #Slope.
  47  * @return True if the slope is non-continuous, else false.
  48  */
  49 static inline bool IsHalftileSlope(Slope s)
  50 {
  51         return (s & SLOPE_HALFTILE) != 0;
  52 }
  53
  54 /**
  55  * Removes a halftile slope from a slope
  56  *
  57  * Non-halftile slopes remain unmodified.
  58  *
  59  * @param s A #Slope.
  60  * @return The slope s without its halftile slope.
  61  */
  62 static inline Slope RemoveHalftileSlope(Slope s)
  63 {
  64         return s & ~SLOPE_HALFTILE_MASK;
  65 }
  66
  67 /**
  68  * Return the complement of a slope.
  69  *
  70  * This method returns the complement of a slope. The complement of a
  71  * slope is a slope with raised corner which aren't raised in the given
  72  * slope.
  73  *
  74  * @pre The slope must neither be steep nor a halftile slope.
  75  * @param s The #Slope to get the complement.
  76  * @return a complement Slope of the given slope.
  77  */
  78 static inline Slope ComplementSlope(Slope s)
  79 {
  80         assert(!IsSteepSlope(s) && !IsHalftileSlope(s));
  81         return s ^ SLOPE_ELEVATED;
  82 }
  83
  84 /**
  85  * Tests if a specific slope has exactly one corner raised.
  86  *
  87  * @param s The #Slope
  88  * @return true iff exactly one corner is raised
  89  */
  90 static inline bool IsSlopeWithOneCornerRaised(Slope s)
  91 {
  92         return (s == SLOPE_W) || (s == SLOPE_S) || (s == SLOPE_E) || (s == SLOPE_N);
  93 }
  94
  95 /**
  96  * Returns the slope with a specific corner raised.
  97  *
  98  * @param corner The #Corner.
  99  * @return The #Slope with corner "corner" raised.
 100  */
 101 static inline Slope SlopeWithOneCornerRaised(Corner corner)
 102 {
 103         assert(IsValidCorner(corner));
 104         return (Slope)(1 << corner);
 105 }
 106
 107 /**
 108  * Tests if a slope has a highest corner (i.e. one corner raised or a steep slope).
 109  *
 110  * Note: A halftile slope is ignored.
 111  *
 112  * @param s The #Slope.
 113  * @return  true iff the slope has a highest corner.
 114  */
 115 static inline bool HasSlopeHighestCorner(Slope s)
 116 {
 117         s = RemoveHalftileSlope(s);
 118         return IsSteepSlope(s) || IsSlopeWithOneCornerRaised(s);
 119 }
 120
 121 /**
 122  * Returns the highest corner of a slope (one corner raised or a steep slope).
 123  *
 124  * @pre      The slope must be a slope with one corner raised or a steep slope. A halftile slope is ignored.
 125  * @param s  The #Slope.
 126  * @return   Highest corner.
 127  */
 128 static inline Corner GetHighestSlopeCorner(Slope s)
 129 {
 130         switch (RemoveHalftileSlope(s)) {
 131                 case SLOPE_W:
 132                 case SLOPE_STEEP_W: return CORNER_W;
 133                 case SLOPE_S:
 134                 case SLOPE_STEEP_S: return CORNER_S;
 135                 case SLOPE_E:
 136                 case SLOPE_STEEP_E: return CORNER_E;
 137                 case SLOPE_N:
 138                 case SLOPE_STEEP_N: return CORNER_N;
 139                 default: NOT_REACHED();
 140         }
 141 }
 142
 143 /**
 144  * Returns the leveled halftile of a halftile slope.
 145  *
 146  * @pre     The slope must be a halftile slope.
 147  * @param s The #Slope.
 148  * @return  The corner of the leveled halftile.
 149  */
 150 static inline Corner GetHalftileSlopeCorner(Slope s)
 151 {
 152         assert(IsHalftileSlope(s));
 153         return (Corner)((s >> 6) & 3);
 154 }
 155
 156 /**
 157  * Returns the height of the highest corner of a slope relative to TileZ (= minimal height)
 158  *
 159  * @param s The #Slope.
 160  * @return Relative height of highest corner.
 161  */
 162 static inline int GetSlopeMaxZ(Slope s)
 163 {
 164         if (s == SLOPE_FLAT) return 0;
 165         if (IsSteepSlope(s)) return 2;
 166         return 1;
 167 }
 168
 169 /**
 170  * Returns the height of the highest corner of a slope relative to TileZ (= minimal height)
 171  *
 172  * @param s The #Slope.
 173  * @return Relative height of highest corner.
 174  */
 175 static inline int GetSlopeMaxPixelZ(Slope s)
 176 {
 177         return GetSlopeMaxZ(s) * TILE_HEIGHT;
 178 }
 179
 180 /**
 181  * Returns the opposite corner.
 182  *
 183  * @param corner A #Corner.
 184  * @return The opposite corner to "corner".
 185  */
 186 static inline Corner OppositeCorner(Corner corner)
 187 {
 188         return (Corner)(corner ^ 2);
 189 }
 190
 191 /**
 192  * Tests if a specific slope has exactly three corners raised.
 193  *
 194  * @param s The #Slope
 195  * @return true iff exactly three corners are raised
 196  */
 197 static inline bool IsSlopeWithThreeCornersRaised(Slope s)
 198 {
 199         return !IsHalftileSlope(s) && !IsSteepSlope(s) && IsSlopeWithOneCornerRaised(ComplementSlope(s));
 200 }
 201
 202 /**
 203  * Returns the slope with all except one corner raised.
 204  *
 205  * @param corner The #Corner.
 206  * @return The #Slope with all corners but "corner" raised.
 207  */
 208 static inline Slope SlopeWithThreeCornersRaised(Corner corner)
 209 {
 210         return ComplementSlope(SlopeWithOneCornerRaised(corner));
 211 }
 212
 213 /**
 214  * Returns a specific steep slope
 215  *
 216  * @param corner A #Corner.
 217  * @return The steep #Slope with "corner" as highest corner.
 218  */
 219 static inline Slope SteepSlope(Corner corner)
 220 {
 221         return SLOPE_STEEP | SlopeWithThreeCornersRaised(OppositeCorner(corner));
 222 }
 223
 224 /**
 225  * Tests if a specific slope is an inclined slope.
 226  *
 227  * @param s The #Slope
 228  * @return true iff the slope is inclined.
 229  */
 230 static inline bool IsInclinedSlope(Slope s)
 231 {
 232         return (s == SLOPE_NW) || (s == SLOPE_SW) || (s == SLOPE_SE) || (s == SLOPE_NE);
 233 }
 234
 235 /**
 236  * Returns the direction of an inclined slope.
 237  *
 238  * @param s A #Slope
 239  * @return The direction the slope goes up in. Or INVALID_DIAGDIR if the slope is not an inclined slope.
 240  */
 241 static inline DiagDirection GetInclinedSlopeDirection(Slope s)
 242 {
 243         switch (s) {
 244                 case SLOPE_NE: return DIAGDIR_NE;
 245                 case SLOPE_SE: return DIAGDIR_SE;
 246                 case SLOPE_SW: return DIAGDIR_SW;
 247                 case SLOPE_NW: return DIAGDIR_NW;
 248                 default: return INVALID_DIAGDIR;
 249         }
 250 }
 251
 252 /**
 253  * Returns the slope that is inclined in a specific direction.
 254  *
 255  * @param dir A #DiagDirection
 256  * @return The #Slope that goes up in direction dir.
 257  */
 258 static inline Slope InclinedSlope(DiagDirection dir)
 259 {
 260         switch (dir) {
 261                 case DIAGDIR_NE: return SLOPE_NE;
 262                 case DIAGDIR_SE: return SLOPE_SE;
 263                 case DIAGDIR_SW: return SLOPE_SW;
 264                 case DIAGDIR_NW: return SLOPE_NW;
 265                 default: NOT_REACHED();
 266         }
 267 }
 268
 269 /**
 270  * Adds a halftile slope to a slope.
 271  *
 272  * @param s #Slope without a halftile slope.
 273  * @param corner The #Corner of the halftile.
 274  * @return The #Slope s with the halftile slope added.
 275  */
 276 static inline Slope HalftileSlope(Slope s, Corner corner)
 277 {
 278         assert(IsValidCorner(corner));
 279         return (Slope)(s | SLOPE_HALFTILE | (corner << 6));
 280 }
 281
 282
 283 /**
 284  * Tests for FOUNDATION_NONE.
 285  *
 286  * @param f  Maybe a #Foundation.
 287  * @return   true iff f is a foundation.
 288  */
 289 static inline bool IsFoundation(Foundation f)
 290 {
 291         return f != FOUNDATION_NONE;
 292 }
 293
 294 /**
 295  * Tests if the foundation is a leveled foundation.
 296  *
 297  * @param f  The #Foundation.
 298  * @return   true iff f is a leveled foundation.
 299  */
 300 static inline bool IsLeveledFoundation(Foundation f)
 301 {
 302         return f == FOUNDATION_LEVELED;
 303 }
 304
 305 /**
 306  * Tests if the foundation is an inclined foundation.
 307  *
 308  * @param f  The #Foundation.
 309  * @return   true iff f is an inclined foundation.
 310  */
 311 static inline bool IsInclinedFoundation(Foundation f)
 312 {
 313         return (f == FOUNDATION_INCLINED_X) || (f == FOUNDATION_INCLINED_Y);
 314 }
 315
 316 /**
 317  * Tests if a foundation is a non-continuous foundation, i.e. halftile-foundation or FOUNDATION_STEEP_BOTH.
 318  *
 319  * @param f  The #Foundation.
 320  * @return   true iff f is a non-continuous foundation
 321  */
 322 static inline bool IsNonContinuousFoundation(Foundation f)
 323 {
 324         return IsInsideMM(f, FOUNDATION_STEEP_BOTH, FOUNDATION_HALFTILE_N + 1);
 325 }
 326
 327 /**
 328  * Returns the halftile corner of a halftile-foundation
 329  *
 330  * @pre f != FOUNDATION_STEEP_BOTH
 331  *
 332  * @param f  The #Foundation.
 333  * @return   The #Corner with track.
 334  */
 335 static inline Corner GetHalftileFoundationCorner(Foundation f)
 336 {
 337         assert(IsInsideMM(f, FOUNDATION_HALFTILE_W, FOUNDATION_HALFTILE_N + 1));
 338         return (Corner)(f - FOUNDATION_HALFTILE_W);
 339 }
 340
 341 /**
 342  * Tests if a foundation is a special rail foundation for single horizontal/vertical track.
 343  *
 344  * @param f  The #Foundation.
 345  * @return   true iff f is a special rail foundation for single horizontal/vertical track.
 346  */
 347 static inline bool IsSpecialRailFoundation(Foundation f)
 348 {
 349         return IsInsideMM(f, FOUNDATION_RAIL_W, FOUNDATION_RAIL_N + 1);
 350 }
 351
 352 /**
 353  * Returns the track corner of a special rail foundation
 354  *
 355  * @param f  The #Foundation.
 356  * @return   The #Corner with track.
 357  */
 358 static inline Corner GetRailFoundationCorner(Foundation f)
 359 {
 360         assert(IsSpecialRailFoundation(f));
 361         return (Corner)(f - FOUNDATION_RAIL_W);
 362 }
 363
 364 /**
 365  * Returns the foundation needed to flatten a slope.
 366  * The returned foundation is either FOUNDATION_NONE if the tile was already flat, or FOUNDATION_LEVELED.
 367  *
 368  * @param s  The current #Slope.
 369  * @return   The needed #Foundation.
 370  */
 371 static inline Foundation FlatteningFoundation(Slope s)
 372 {
 373         return (s == SLOPE_FLAT ? FOUNDATION_NONE : FOUNDATION_LEVELED);
 374 }
 375
 376 /**
 377  * Returns the along a specific axis inclined foundation.
 378  *
 379  * @param axis  The #Axis.
 380  * @return      The needed #Foundation.
 381  */
 382 static inline Foundation InclinedFoundation(Axis axis)
 383 {
 384         return (axis == AXIS_X ? FOUNDATION_INCLINED_X : FOUNDATION_INCLINED_Y);
 385 }
 386
 387 /**
 388  * Returns the halftile foundation for single horizontal/vertical track.
 389  *
 390  * @param corner The #Corner with the track.
 391  * @return       The wanted #Foundation.
 392  */
 393 static inline Foundation HalftileFoundation(Corner corner)
 394 {
 395         assert(IsValidCorner(corner));
 396         return (Foundation)(FOUNDATION_HALFTILE_W + corner);
 397 }
 398
 399 /**
 400  * Returns the special rail foundation for single horizontal/vertical track.
 401  *
 402  * @param corner The #Corner with the track.
 403  * @return       The wanted #Foundation.
 404  */
 405 static inline Foundation SpecialRailFoundation(Corner corner)
 406 {
 407         assert(IsValidCorner(corner));
 408         return (Foundation)(FOUNDATION_RAIL_W + corner);
 409 }
 410
 411 /**
 412  * Returns the #Sprite offset for a given #Slope.
 413  *
 414  * @param s The #Slope to get the offset for.
 415  * @return The sprite offset for this #Slope.
 416  */
 417 static inline uint SlopeToSpriteOffset(Slope s)
 418 {
 419         extern const byte _slope_to_sprite_offset[32];
 420         return _slope_to_sprite_offset[s];
 421 }
 422
 423 #endif /* SLOPE_FUNC_H */