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/* $Id$ */
#ifndef DIRECTION_H
#define DIRECTION_H
/* Direction as commonly used in v->direction, 8 way. */
typedef enum Direction {
DIR_N = 0,
DIR_NE = 1, /* Northeast, upper right on your monitor */
DIR_E = 2,
DIR_SE = 3,
DIR_S = 4,
DIR_SW = 5,
DIR_W = 6,
DIR_NW = 7,
DIR_END,
INVALID_DIR = 0xFF,
} Direction;
static inline Direction ReverseDir(Direction d)
{
return (Direction)(4 ^ d);
}
typedef enum DirDiff {
DIRDIFF_SAME = 0,
DIRDIFF_45RIGHT = 1,
DIRDIFF_90RIGHT = 2,
DIRDIFF_REVERSE = 4,
DIRDIFF_90LEFT = 6,
DIRDIFF_45LEFT = 7
} DirDiff;
static inline DirDiff DirDifference(Direction d0, Direction d1)
{
return (DirDiff)((d0 + 8 - d1) % 8);
}
static inline DirDiff ChangeDirDiff(DirDiff d, DirDiff delta)
{
return (DirDiff)((d + delta) % 8);
}
static inline Direction ChangeDir(Direction d, DirDiff delta)
{
return (Direction)((d + delta) % 8);
}
/* Direction commonly used as the direction of entering and leaving tiles, 4-way */
typedef enum DiagDirection {
DIAGDIR_NE = 0, /* Northeast, upper right on your monitor */
DIAGDIR_SE = 1,
DIAGDIR_SW = 2,
DIAGDIR_NW = 3,
DIAGDIR_END,
INVALID_DIAGDIR = 0xFF,
} DiagDirection;
static inline DiagDirection ReverseDiagDir(DiagDirection d)
{
return (DiagDirection)(2 ^ d);
}
typedef enum DiagDirDiff {
DIAGDIRDIFF_SAME = 0,
DIAGDIRDIFF_90RIGHT = 1,
DIAGDIRDIFF_REVERSE = 2,
DIAGDIRDIFF_90LEFT = 3
} DiagDirDiff;
static inline DiagDirection ChangeDiagDir(DiagDirection d, DiagDirDiff delta)
{
return (DiagDirection)((d + delta) % 4);
}
static inline DiagDirection DirToDiagDir(Direction dir)
{
return (DiagDirection)(dir >> 1);
}
static inline Direction DiagDirToDir(DiagDirection dir)
{
return (Direction)(dir * 2 + 1);
}
/* the 2 axis */
typedef enum Axis {
AXIS_X = 0,
AXIS_Y = 1
} Axis;
static inline Axis DiagDirToAxis(DiagDirection d)
{
return (Axis)(d & 1);
}
/*
* Converts an Axis to a DiagDirection
* Points always in the positive direction, i.e. S[EW]
*/
static inline DiagDirection AxisToDiagDir(Axis a)
{
return (DiagDirection)(2 - a);
}
#endif
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