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/* $Id$ */
/** @file slope.h Definitions of a slope.
* This file defines the enumeration and helper functions for handling
* the slope info of a tile.
*/
#ifndef SLOPE_H
#define SLOPE_H
/**
* Enumeration for the slope-type.
*
* This enumeration use the chars N,E,S,W corresponding the
* direction north, east, south and west. The top corner of a tile
* is the north-part of the tile. The whole slope is encoded with
* 5 bits, 4 bits for each corner and 1 bit for a steep-flag.
*/
enum Slope {
SLOPE_FLAT = 0x00, ///< a flat tile
SLOPE_W = 0x01, ///< the west corner of the tile is raised
SLOPE_S = 0x02, ///< the south corner of the tile is raised
SLOPE_E = 0x04, ///< the east corner of the tile is raised
SLOPE_N = 0x08, ///< the north corner of the tile is raised
SLOPE_STEEP = 0x10, ///< indicates the slope is steep
SLOPE_NW = SLOPE_N | SLOPE_W, ///< north and west corner are raised
SLOPE_SW = SLOPE_S | SLOPE_W, ///< south and west corner are raised
SLOPE_SE = SLOPE_S | SLOPE_E, ///< south and east corner are raised
SLOPE_NE = SLOPE_N | SLOPE_E, ///< north and east corner are raised
SLOPE_EW = SLOPE_E | SLOPE_W, ///< east and west corner are raised
SLOPE_NS = SLOPE_N | SLOPE_S, ///< north and south corner are raised
SLOPE_ELEVATED = SLOPE_N | SLOPE_E | SLOPE_S | SLOPE_W, ///< all corner are raised, similar to SLOPE_FLAT
SLOPE_NWS = SLOPE_N | SLOPE_W | SLOPE_S, ///< north, west and south corner are raised
SLOPE_WSE = SLOPE_W | SLOPE_S | SLOPE_E, ///< west, south and east corner are raised
SLOPE_SEN = SLOPE_S | SLOPE_E | SLOPE_N, ///< south, east and north corner are raised
SLOPE_ENW = SLOPE_E | SLOPE_N | SLOPE_W, ///< east, north and west corner are raised
SLOPE_STEEP_W = SLOPE_STEEP | SLOPE_NWS, ///< a steep slope falling to east (from west)
SLOPE_STEEP_S = SLOPE_STEEP | SLOPE_WSE, ///< a steep slope falling to north (from south)
SLOPE_STEEP_E = SLOPE_STEEP | SLOPE_SEN, ///< a steep slope falling to west (from east)
SLOPE_STEEP_N = SLOPE_STEEP | SLOPE_ENW ///< a steep slope falling to south (from north)
};
/**
* Checks if a slope is steep.
*
* @param s The given #Slope.
* @return True if the slope is steep, else false.
*/
static inline bool IsSteepSlope(Slope s)
{
return (s & SLOPE_STEEP) != 0;
}
/**
* Return the complement of a slope.
*
* This method returns the complement of a slope. The complement of a
* slope is a slope with raised corner which aren't raised in the given
* slope.
*
* @pre The slope must not be steep.
* @param s The #Slope to get the complement.
* @return a complement Slope of the given slope.
*/
static inline Slope ComplementSlope(Slope s)
{
assert(!IsSteepSlope(s));
return (Slope)(0xF ^ s);
}
/**
* Returns the highest corner of a slope (one corner raised or a steep slope).
*
* @pre The slope must be a slope with one corner raised or a steep slope.
* @param s The #Slope.
* @return Number of the highest corner. (0 west, 1 south, 2 east, 3 north)
*/
static inline byte GetHighestSlopeCorner(Slope s)
{
switch (s) {
case SLOPE_W:
case SLOPE_STEEP_W: return 0;
case SLOPE_S:
case SLOPE_STEEP_S: return 1;
case SLOPE_E:
case SLOPE_STEEP_E: return 2;
case SLOPE_N:
case SLOPE_STEEP_N: return 3;
default: NOT_REACHED();
}
}
/**
* Enumeration for Foundations.
*/
enum Foundation {
FOUNDATION_NONE, ///< The tile has no foundation, the slope remains unchanged.
FOUNDATION_LEVELED, ///< The tile is leveled up to a flat slope.
FOUNDATION_INCLINED_X, ///< The tile has an along X-axis inclined foundation.
FOUNDATION_INCLINED_Y, ///< The tile has an along Y-axis inclined foundation.
FOUNDATION_STEEP_LOWER, ///< The tile has a steep slope. The lowerst corner is raised by a foundation to allow building railroad on the lower halftile.
FOUNDATION_STEEP_HIGHER, ///< The tile has a steep slope. Three corners are raised by a foundation to allow building railroad on the higher halftile.
};
/**
* Tests for FOUNDATION_NONE.
*
* @param f Maybe a #Foundation.
* @return true iff f is a foundation.
*/
static inline bool IsFoundation(Foundation f)
{
return f != FOUNDATION_NONE;
}
/**
* Tests if the foundation is a leveled foundation.
*
* @param f The #Foundation.
* @return true iff f is a leveled foundation.
*/
static inline bool IsLeveledFoundation(Foundation f)
{
return f == FOUNDATION_LEVELED;
}
/**
* Tests if the foundation is an inclined foundation.
*
* @param f The #Foundation.
* @return true iff f is an inclined foundation.
*/
static inline bool IsInclinedFoundation(Foundation f)
{
return (f == FOUNDATION_INCLINED_X) || (f == FOUNDATION_INCLINED_Y);
}
/**
* Returns the foundation needed to flatten a slope.
* The returned foundation is either FOUNDATION_NONE if the tile was already flat, or FOUNDATION_LEVELED.
*
* @pre The slope must not be steep.
* @param s The current #Slope.
* @return The needed #Foundation.
*/
static inline Foundation FlatteningFoundation(Slope s)
{
assert(!IsSteepSlope(s));
return (s == SLOPE_FLAT ? FOUNDATION_NONE : FOUNDATION_LEVELED);
}
/**
* Returns the along a specific axis inclined foundation.
*
* @param axis The #Axis.
* @return The needed #Foundation.
*/
static inline Foundation InclinedFoundation(Axis axis)
{
return (axis == AXIS_X ? FOUNDATION_INCLINED_X : FOUNDATION_INCLINED_Y);
}
#endif /* SLOPE_H */
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