direction_util.h

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program 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, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#ifndef ULTIMA8_MISC_DIRECTIONUTIL_H
#define ULTIMA8_MISC_DIRECTIONUTIL_H

#include "ultima/ultima8/misc/direction.h"
#include "ultima/ultima8/ultima8.h"
#include "math/utils.h"

namespace Ultima {
namespace Ultima8 {

/*
 * Tables to map a Direction to x/y deltas
 */


inline int Direction_XFactor(Direction dir) {
    static const int _x_fact[] = {  0, +1, +1, +1,  0, -1, -1, -1 };
    static const int _x_fact16[] = {  0, +1, +1, +2, +1, +2, +1, +1, 0, -1, -1, -2, -1, -2, -1, -1, 0 };

    assert((int)dir >= 0 && (int)dir < 16);

    if (GAME_IS_U8)
        return _x_fact[(int)dir / 2];
    else
        return _x_fact16[(int)dir];
}

inline int Direction_YFactor(Direction dir) {
    static const int _y_fact[] = { -1, -1,  0, +1, +1, +1,  0, -1 };
    static const int _y_fact16[] = { -1, -2, -1, -1, 0, +1, +1, +2, +1, +2, +1, +1, 0, -1, -1, -2, 0 };

    assert((int)dir >= 0 && (int)dir < 16);

    if (GAME_IS_U8)
        return _y_fact[(int)dir / 2];
    else
        return _y_fact16[(int)dir];
}

inline int32 Direction_ToCentidegrees(Direction dir) {
    return static_cast<int>(dir) * 2250;
}

inline Direction Direction_FromCentidegrees(int32 cds) {
    return static_cast<Direction>(((cds + 1125) / 2250) % 16);
}


inline Direction Direction_Get(int deltay, int deltax, DirectionMode dirmode) {
    if (deltax == 0)
        return deltay > 0 ? dir_northwest : dir_southeast;

    if (dirmode == dirmode_8dirs) {
        int dydx = (1024 * deltay) / deltax; // Figure 1024*tan.
        if (dydx >= 0)
            if (deltax > 0) // Top-right
                return dydx <= 424 ? dir_northeast : dydx <= 2472 ? dir_north
                       : dir_northwest;
            else            // Bottom-left.
                return dydx <= 424 ? dir_southwest : dydx <= 2472 ? dir_south
                       : dir_southeast;
        else if (deltax > 0) // Bottom-right.
            return dydx >= -424 ? dir_northeast : dydx >= -2472 ? dir_east
                   : dir_southeast;
        else            // Top-left
            return dydx >= -424 ? dir_southwest : dydx >= -2472 ? dir_west
                   : dir_northwest;
    } else {
        double angle = Math::rad2deg(atan2(deltay, deltax));
        if (angle < -168.75)      return dir_southwest;
        else if (angle < -146.25) return dir_ssw;
        else if (angle < -123.75) return dir_south;
        else if (angle < -101.25) return dir_sse;
        else if (angle < -78.75)  return dir_southeast;
        else if (angle < -56.25)  return dir_ese;
        else if (angle < -33.75)  return dir_east;
        else if (angle < -11.25)  return dir_ene;
        else if (angle < 11.25)   return dir_northeast;
        else if (angle < 33.75)   return dir_nne;
        else if (angle < 56.25)   return dir_north;
        else if (angle < 78.75)   return dir_nnw;
        else if (angle < 101.25)  return dir_northwest;
        else if (angle < 123.75)  return dir_wnw;
        else if (angle < 146.25)  return dir_west;
        else if (angle < 168.75)  return dir_wsw;
        return dir_southwest;
    }
}

// Note that for WorldDir, Y goes down, so a positive Y points south.
inline Direction Direction_GetWorldDir(int deltay, int deltax, DirectionMode dirmode) {
    if (deltax == 0) {
        if (deltay == 0) return dir_northeast; // for better compatibility with U8
        return deltay > 0 ? dir_south : dir_north;
    }

    if (dirmode == dirmode_8dirs) {
        int dydx = (1024 * deltay) / deltax;

        if (dydx >= 0)
            if (deltax > 0) // south-east
                return dydx <= 424 ? dir_east : dydx <= 2472 ? dir_southeast : dir_south;
            else            // north-west
                return dydx <= 424 ? dir_west : dydx <= 2472 ? dir_northwest : dir_north;
        else if (deltax > 0) // north-east
            return dydx >= -424 ? dir_east : dydx >= -2472 ? dir_northeast : dir_north;
        else            // south-west
            return dydx >= -424 ? dir_west : dydx >= -2472 ? dir_southwest : dir_south;
    } else {
        double angle = Math::rad2deg(atan2(deltay, deltax));
        if (angle < -168.75)      return dir_west;
        else if (angle < -146.25) return dir_wnw;
        else if (angle < -123.75) return dir_northwest;
        else if (angle < -101.25) return dir_nnw;
        else if (angle < -78.75)  return dir_north;
        else if (angle < -56.25)  return dir_nne;
        else if (angle < -33.75)  return dir_northeast;
        else if (angle < -11.25)  return dir_ene;
        else if (angle < 11.25)   return dir_east;
        else if (angle < 33.75)   return dir_ese;
        else if (angle < 56.25)   return dir_southeast;
        else if (angle < 78.75)   return dir_sse;
        else if (angle < 101.25)  return dir_south;
        else if (angle < 123.75)  return dir_ssw;
        else if (angle < 146.25)  return dir_southwest;
        else if (angle < 168.75)  return dir_wsw;
        return dir_west;
    }
}



inline Direction Direction_GetWorldDirInRange(int deltay, int deltax, DirectionMode dirmode, Direction mindir, Direction maxdir) {
    int ndirs = (dirmode == dirmode_8dirs ? 8 : 16);
    Direction dir = Direction_GetWorldDir(deltay, deltax, dirmode);

    if ((dir < mindir) || (dir > maxdir)) {
        int32 dmin1 = dir - mindir;
        int32 dmin2 = mindir - dir;
        if (dmin1 < 0) {
            dmin1 = dmin1 + ndirs;
        }
        if (dmin2 < 0) {
            dmin2 = dmin2 + ndirs;
        }
        int32 dist_to_min = MIN(dmin1, dmin2);

        int dmax1 = dir - maxdir;
        int dmax2 = maxdir - dir;
        if (dmax1 < 0) {
            dmax1 = dmax1 + ndirs;
        }
        if (dmax2 < 0) {
            dmax2 = dmax2 + ndirs;
        }
        int32 dist_to_max = MIN(dmax1, dmax2);

        if (dist_to_min < dist_to_max) {
            return mindir;
        } else {
            return maxdir;
        }
    }

    return dir;
}

inline Direction Direction_Invert(Direction dir) {
    assert(dir != dir_current);
    switch (dir) {
        case dir_north:     return dir_south;
        case dir_nne:       return dir_ssw;
        case dir_northeast: return dir_southwest;
        case dir_ene:       return dir_wsw;
        case dir_east:      return dir_west;
        case dir_ese:       return dir_wnw;
        case dir_southeast: return dir_northwest;
        case dir_sse:       return dir_nnw;
        case dir_south:     return dir_north;
        case dir_ssw:       return dir_nne;
        case dir_southwest: return dir_northeast;
        case dir_wsw:       return dir_ene;
        case dir_west:      return dir_east;
        case dir_wnw:       return dir_ese;
        case dir_northwest: return dir_southeast;
        case dir_nnw:       return dir_sse;
        default:            return dir_north;
    }
}

inline Direction Direction_OneLeft(Direction dir, DirectionMode mode) {
    if (mode == dirmode_8dirs)
        return static_cast<Direction>((static_cast<int>(dir) + 14) % 16);
    else
        return static_cast<Direction>((static_cast<int>(dir) + 15) % 16);
}

inline Direction Direction_OneRight(Direction dir, DirectionMode mode) {
    if (mode == dirmode_8dirs)
        return static_cast<Direction>((static_cast<int>(dir) + 2) % 16);
    else
        return static_cast<Direction>((static_cast<int>(dir) + 1) % 16);
}

inline Direction Direction_TurnByDelta(Direction dir, int delta, DirectionMode mode) {
    if (delta > 0) {
        for (int i = 0; i < delta; i++)
            dir = Direction_OneRight(dir, mode);
    } else if (delta < 0) {
        for (int i = 0; i < -delta; i++)
            dir = Direction_OneLeft(dir, mode);
    }
    return dir;
}

inline int Direction_GetShorterTurnDelta(Direction from, Direction to) {
    if ((from - to + 16) % 16 < 8)
        return -1;
    return 1;
}

inline uint32 Direction_ToUsecodeDir(Direction dir) {
    if (GAME_IS_U8) {
        return static_cast<int32>(dir / 2);
    } else {
        return static_cast<int32>(dir);
    }
}

inline Direction Direction_FromUsecodeDir(uint32 dir) {
    if (GAME_IS_U8) {
        return static_cast<Direction>(dir * 2);
    } else {
        return static_cast<Direction>(dir);
    }
}

} // End of namespace Ultima8
} // End of namespace Ultima

#endif