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");
17 s->w = img->w; s->h = img->h;
18 s->mw = ((img->w+31)>>5);
19 s->mask = malloc(4*s->mw*s->h);
21 fprintf(stderr, "can't malloc bitmask");
27 transp = img->format->colorkey;
29 for(y=0; y<img->h; y++) {
31 for(x=0; x<img->w; x++) {
32 if(!bit) { bits = 0; bit = 0x80000000; }
33 if(*px++ != transp) { bits |= bit; s->area++; }
35 if(!bit || x == img->w - 1) { *(p++) = bits; }
37 px = (uint16_t *) ((uint8_t *) px + img->pitch - 2*img->w);
39 SDL_UnlockSurface(img);
43 #define max(a, b) ((a) > (b) ? (a) : (b))
47 #define min(a, b) ((a) < (b) ? (a) : (b))
51 #define abs(a) ((a)<=0 ? -(a) : (a))
55 line_collide(int xov, struct shape *r, uint32_t *rbits, struct shape *s, uint32_t *sbits)
57 int lshift, n, i, ret = 0;
64 st = r; r = s; s = st;
65 bt = rbits; rbits = sbits; sbits = bt;
70 lshift = (r->w - xov) & 31;
71 rbits += (r->w - xov) >> 5;
73 for(i=0; i<n-1; i++) {
74 lbits = *rbits++ << lshift;
75 lbits |= *rbits >> (32 - lshift);
76 if(lbits & *sbits++) ret = 1;
78 lbits = *rbits << lshift;
79 if(lbits & *sbits) ret = 1;
85 mask_collide(int xov, int yov, struct shape *r, struct shape *s)
88 uint32_t *rbits, *sbits;
91 ry = r->h - yov; sy = 0;
92 rbits = r->mask + (r->h - yov) * r->mw;
95 ry = 0; sy = s->h + yov;
97 sbits = s->mask + (s->h + yov) * s->mw;
100 for(y=0; y<abs(yov); y++) {
101 if(line_collide(xov, r, rbits, s, sbits)) return 1;
102 rbits += r->mw; sbits += s->mw;
109 collide(int xdiff, int ydiff, struct shape *r, struct shape *s)
113 if(xdiff >= 0) xov = max(min(r->w-xdiff, s->w), 0);
114 else xov = min(-min(s->w+xdiff, r->w), 0);
116 if(ydiff >= 0) yov = max(min(r->h-ydiff, s->h), 0);
117 else yov = min(-min(s->h+ydiff, r->h), 0);
119 if(xov == 0 || yov == 0) return 0; // bboxes hit?
120 else return mask_collide(xov, yov, r, s);