172 lines
4.8 KiB
C
172 lines
4.8 KiB
C
/*
|
|
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 or equal to 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);
|
|
|
|
/* Create a copy of the given bitmask. */
|
|
bitmask_t *
|
|
bitmask_copy(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);
|
|
|
|
/* Convolve b into a, drawing the output into o, shifted by offset. If offset
|
|
* is 0, then the (x,y) bit will be set if and only if
|
|
* bitmask_overlap(a, b, x - b->w - 1, y - b->h - 1) returns true.
|
|
*
|
|
* Modifies bits o[xoffset ... xoffset + a->w + b->w - 1)
|
|
* [yoffset ... yoffset + a->h + b->h - 1). */
|
|
void
|
|
bitmask_convolve(const bitmask_t *a, const bitmask_t *b, bitmask_t *o,
|
|
int xoffset, int yoffset);
|
|
|
|
#ifdef __cplusplus
|
|
} /* End of extern "C" { */
|
|
#endif
|
|
|
|
#endif
|