5 get_shape(SDL_Surface *img, struct shape *s)
9 uint32_t bits, bit, *p;
11 if(img->format->BytesPerPixel != 2) {
12 fprintf(stderr, "get_shape(): not a 16-bit image!\n");
16 s->w = img->w; s->h = img->h;
17 s->mw = ((img->w+31)>>5);
18 s->mask = malloc(4*s->mw*s->h);
20 fprintf(stderr, "can't malloc bitmask");
26 transp = img->format->colorkey;
28 for(y=0; y<img->h; y++) {
30 for(x=0; x<img->w; x++) {
31 if(!bit) { bits = 0; bit = 0x80000000; }
32 if(*px++ != transp) bits |= bit;
34 if(!bit || x == img->w - 1) { *(p++) = bits; }
36 px = (uint16_t *) ((uint8_t *) px + img->pitch - 2*img->w);
38 SDL_UnlockSurface(img);
42 #define max(a, b) ((a) > (b) ? (a) : (b))
46 #define min(a, b) ((a) < (b) ? (a) : (b))
50 #define abs(a) ((a)<=0 ? -(a) : (a))
54 line_collide(int xov, struct shape *r, uint32_t *rbits, struct shape *s, uint32_t *sbits)
56 int lshift, n, i, ret = 0;
63 st = r; r = s; s = st;
64 bt = rbits; rbits = sbits; sbits = bt;
69 lshift = (r->w - xov) & 31;
70 rbits += (r->w - xov) >> 5;
72 for(i=0; i<n-1; i++) {
73 lbits = *rbits++ << lshift;
74 lbits |= *rbits >> (32 - lshift);
75 if(lbits & *sbits++) ret = 1;
77 lbits = *rbits << lshift;
78 if(lbits & *sbits) ret = 1;
84 mask_collide(int xov, int yov, struct shape *r, struct shape *s)
87 uint32_t *rbits, *sbits;
90 ry = r->h - yov; sy = 0;
91 rbits = r->mask + (r->h - yov) * r->mw;
94 ry = 0; sy = s->h + yov;
96 sbits = s->mask + (s->h + yov) * s->mw;
99 for(y=0; y<abs(yov); y++) {
100 if(line_collide(xov, r, rbits, s, sbits)) return 1;
101 rbits += r->mw; sbits += s->mw;
108 collide(int xdiff, int ydiff, struct shape *r, struct shape *s)
112 if(xdiff >= 0) xov = max(min(r->w-xdiff, s->w), 0);
113 else xov = min(-min(s->w+xdiff, r->w), 0);
115 if(ydiff >= 0) yov = max(min(r->h-ydiff, s->h), 0);
116 else yov = min(-min(s->h+ydiff, r->h), 0);
118 if(xov == 0 || yov == 0) return 0; // bboxes hit?
119 else return mask_collide(xov, yov, r, s);