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/*
Bitmask 1.7 - A pixel-perfect collision detection library.
Copyright (C) 2002-2005 Ulf Ekstrom except for the bitcount
function which is copyright (C) Donald W. Gillies, 1992.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef BITMASK_H
#define BITMASK_H
#ifdef __cplusplus
extern "C" {
#endif
#include <limits.h>
/* Define INLINE for different compilers. If your compiler does not
support inlining then there might be a performance hit in
bitmask_overlap_area().
*/
#ifndef INLINE
# ifdef __GNUC__
# define INLINE inline
# else
# ifdef _MSC_VER
# define INLINE __inline
# else
# define INLINE
# endif
# endif
#endif
#define BITMASK_W unsigned long int
#define BITMASK_W_LEN (sizeof(BITMASK_W)*CHAR_BIT)
#define BITMASK_W_MASK (BITMASK_W_LEN - 1)
#define BITMASK_N(n) ((BITMASK_W)1 << (n))
typedef struct bitmask
{
int w,h;
BITMASK_W bits[1];
} bitmask_t;
/* Creates a bitmask of width w and height h, where
w and h must both be greater than 0.
The mask is automatically cleared when created.
*/
bitmask_t *bitmask_create(int w, int h);
/* Frees all the memory allocated by bitmask_create for m. */
void bitmask_free(bitmask_t *m);
/* Clears all bits in the mask */
void bitmask_clear(bitmask_t *m);
/* Sets all bits in the mask */
void bitmask_fill(bitmask_t *m);
/* Flips all bits in the mask */
void bitmask_invert(bitmask_t *m);
/* Counts the bits in the mask */
unsigned int bitmask_count(bitmask_t *m);
/* Returns nonzero if the bit at (x,y) is set. Coordinates start at
(0,0) */
static INLINE int bitmask_getbit(const bitmask_t *m, int x, int y)
{
return (m->bits[x/BITMASK_W_LEN*m->h + y] & BITMASK_N(x & BITMASK_W_MASK)) != 0;
}
/* Sets the bit at (x,y) */
static INLINE void bitmask_setbit(bitmask_t *m, int x, int y)
{
m->bits[x/BITMASK_W_LEN*m->h + y] |= BITMASK_N(x & BITMASK_W_MASK);
}
/* Clears the bit at (x,y) */
static INLINE void bitmask_clearbit(bitmask_t *m, int x, int y)
{
m->bits[x/BITMASK_W_LEN*m->h + y] &= ~BITMASK_N(x & BITMASK_W_MASK);
}
/* Returns nonzero if the masks overlap with the given offset.
The overlap tests uses the following offsets (which may be negative):
+----+----------..
|A | yoffset
| +-+----------..
+--|B
|xoffset
| |
: :
*/
int bitmask_overlap(const bitmask_t *a, const bitmask_t *b, int xoffset, int yoffset);
/* Like bitmask_overlap(), but will also give a point of intersection.
x and y are given in the coordinates of mask a, and are untouched
if there is no overlap. */
int bitmask_overlap_pos(const bitmask_t *a, const bitmask_t *b,
int xoffset, int yoffset, int *x, int *y);
/* Returns the number of overlapping 'pixels' */
int bitmask_overlap_area(const bitmask_t *a, const bitmask_t *b, int xoffset, int yoffset);
/* Fills a mask with the overlap of two other masks. A bitwise AND. */
void bitmask_overlap_mask (const bitmask_t *a, const bitmask_t *b, bitmask_t *c, int xoffset, int yoffset);
/* Draws mask b onto mask a (bitwise OR). Can be used to compose large
(game background?) mask from several submasks, which may speed up
the testing. */
void bitmask_draw(bitmask_t *a, const bitmask_t *b, int xoffset, int yoffset);
void bitmask_erase(bitmask_t *a, const bitmask_t *b, int xoffset, int yoffset);
/* Return a new scaled bitmask, with dimensions w*h. The quality of the
scaling may not be perfect for all circumstances, but it should
be reasonable. If either w or h is 0 a clear 1x1 mask is returned. */
bitmask_t *bitmask_scale(const bitmask_t *m, int w, int h);
#ifdef __cplusplus
} /* End of extern "C" { */
#endif
#endif
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