slope_func.h

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/*
 * This file is part of OpenTTD.
 * 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.
 * 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.
 * 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 <https://www.gnu.org/licenses/old-licenses/gpl-2.0>.
 */

 
#ifndef SLOPE_FUNC_H
#define SLOPE_FUNC_H
 
#include "core/math_func.hpp"
#include "slope_type.h"
#include "direction_type.h"
#include "tile_type.h"

static constexpr inline bool IsValidCorner(Corner corner)
{
  return IsInsideMM(corner, 0, CORNER_END);
}
 

static constexpr inline bool IsSteepSlope(Slope s)
{
  return (s & SLOPE_STEEP) != 0;
}

static constexpr Slope RemoveSteepSlope(Slope s)
{
  return s & ~SLOPE_STEEP;
}

static constexpr inline bool IsHalftileSlope(Slope s)
{
  return (s & SLOPE_HALFTILE) != 0;
}

static constexpr inline Slope RemoveHalftileSlope(Slope s)
{
  return s & ~SLOPE_HALFTILE_MASK;
}

inline Slope ComplementSlope(Slope s)
{
  assert(!IsSteepSlope(s) && !IsHalftileSlope(s));
  return s ^ SLOPE_ELEVATED;
}

inline bool IsSlopeWithOneCornerRaised(Slope s)
{
  return (s == SLOPE_W) || (s == SLOPE_S) || (s == SLOPE_E) || (s == SLOPE_N);
}

inline Slope SlopeWithOneCornerRaised(Corner corner)
{
  assert(IsValidCorner(corner));
  return (Slope)(1 << corner);
}

inline bool HasSlopeHighestCorner(Slope s)
{
  s = RemoveHalftileSlope(s);
  return IsSteepSlope(s) || IsSlopeWithOneCornerRaised(s);
}

inline Corner GetHighestSlopeCorner(Slope s)
{
  switch (RemoveHalftileSlope(s)) {
    case SLOPE_W:
    case SLOPE_STEEP_W: return CORNER_W;
    case SLOPE_S:
    case SLOPE_STEEP_S: return CORNER_S;
    case SLOPE_E:
    case SLOPE_STEEP_E: return CORNER_E;
    case SLOPE_N:
    case SLOPE_STEEP_N: return CORNER_N;
    default: NOT_REACHED();
  }
}

static constexpr inline Corner GetHalftileSlopeCorner(Slope s)
{
  assert(IsHalftileSlope(s));
  return (Corner)((s >> 6) & 3);
}

static constexpr inline int GetSlopeMaxZ(Slope s)
{
  if (s == SLOPE_FLAT) return 0;
  if (IsSteepSlope(s)) return 2;
  return 1;
}

static constexpr inline int GetSlopeMaxPixelZ(Slope s)
{
  return GetSlopeMaxZ(s) * TILE_HEIGHT;
}

inline Corner OppositeCorner(Corner corner)
{
  return (Corner)(corner ^ 2);
}

inline bool IsSlopeWithThreeCornersRaised(Slope s)
{
  return !IsHalftileSlope(s) && !IsSteepSlope(s) && IsSlopeWithOneCornerRaised(ComplementSlope(s));
}

inline Slope SlopeWithThreeCornersRaised(Corner corner)
{
  return ComplementSlope(SlopeWithOneCornerRaised(corner));
}

inline Slope SteepSlope(Corner corner)
{
  return SLOPE_STEEP | SlopeWithThreeCornersRaised(OppositeCorner(corner));
}

inline bool IsInclinedSlope(Slope s)
{
  return (s == SLOPE_NW) || (s == SLOPE_SW) || (s == SLOPE_SE) || (s == SLOPE_NE);
}

inline DiagDirection GetInclinedSlopeDirection(Slope s)
{
  switch (s) {
    case SLOPE_NE: return DiagDirection::NE;
    case SLOPE_SE: return DiagDirection::SE;
    case SLOPE_SW: return DiagDirection::SW;
    case SLOPE_NW: return DiagDirection::NW;
    default: return DiagDirection::Invalid;
  }
}

inline Slope InclinedSlope(DiagDirection dir)
{
  switch (dir) {
    case DiagDirection::NE: return SLOPE_NE;
    case DiagDirection::SE: return SLOPE_SE;
    case DiagDirection::SW: return SLOPE_SW;
    case DiagDirection::NW: return SLOPE_NW;
    default: NOT_REACHED();
  }
}

static constexpr inline Slope HalftileSlope(Slope s, Corner corner)
{
  assert(IsValidCorner(corner));
  return (Slope)(s | SLOPE_HALFTILE | (corner << 6));
}
 

inline bool IsFoundation(Foundation f)
{
  return f != Foundation::None;
}

inline bool IsLeveledFoundation(Foundation f)
{
  return f == Foundation::Leveled;
}

inline bool IsInclinedFoundation(Foundation f)
{
  return (f == Foundation::InclinedX) || (f == Foundation::InclinedY);
}

inline bool IsNonContinuousFoundation(Foundation f)
{
  return IsInsideMM(f, Foundation::SteepBoth, Foundation::HalfTileEnd);
}

inline Corner GetHalftileFoundationCorner(Foundation f)
{
  assert(IsInsideMM(f, Foundation::HalfTileW, Foundation::HalfTileEnd));
  return static_cast<Corner>(to_underlying(f) - to_underlying(Foundation::HalfTileW));
}

inline bool IsSpecialRailFoundation(Foundation f)
{
  return IsInsideMM(f, Foundation::RailW, Foundation::End);
}

inline Corner GetRailFoundationCorner(Foundation f)
{
  assert(IsSpecialRailFoundation(f));
  return static_cast<Corner>(to_underlying(f) - to_underlying(Foundation::RailW));
}

inline Foundation FlatteningFoundation(Slope s)
{
  return (s == SLOPE_FLAT ? Foundation::None : Foundation::Leveled);
}

inline Foundation InclinedFoundation(Axis axis)
{
  return (axis == Axis::X ? Foundation::InclinedX : Foundation::InclinedY);
}

inline Foundation HalftileFoundation(Corner corner)
{
  assert(IsValidCorner(corner));
  return static_cast<Foundation>(static_cast<uint>(Foundation::HalfTileW) + static_cast<uint>(corner));
}

inline Foundation SpecialRailFoundation(Corner corner)
{
  assert(IsValidCorner(corner));
  return static_cast<Foundation>(static_cast<uint>(Foundation::RailW) + static_cast<uint>(corner));
}

inline uint SlopeToSpriteOffset(Slope s)
{
  extern const uint8_t _slope_to_sprite_offset[32];
  return _slope_to_sprite_offset[s];
}
 
#endif /* SLOPE_FUNC_H */