6 get_shape(SDL_Surface *img, struct shape *s)
10 uint32_t bits = 0, bit, *p;
12 if(img->format->BytesPerPixel != 2) {
13 fprintf(stderr, "get_shape(): not a 16-bit image!\n");
18 s->w = img->w; s->h = img->h;
19 s->mw = ((img->w+31)>>5);
20 s->mask = malloc(4*s->mw*s->h);
22 fprintf(stderr, "can't malloc bitmask");
28 transp = img->format->colorkey;
30 for(y=0; y<img->h; y++) {
32 for(x=0; x<img->w; x++) {
33 if(!bit) { bits = 0; bit = 0x80000000; }
34 if(*px++ != transp) { bits |= bit; s->area++; }
36 if(!bit || x == img->w - 1) { *(p++) = bits; }
38 px = (uint16_t *) ((uint8_t *) px + img->pitch - 2*img->w);
40 SDL_UnlockSurface(img);
44 line_collide(int xov, struct shape *r, uint32_t *rbits, struct shape *s, uint32_t *sbits)
46 int lshift, n, i, ret = 0;
53 st = r; r = s; s = st;
54 bt = rbits; rbits = sbits; sbits = bt;
59 lshift = (r->w - xov) & 31;
60 rbits += (r->w - xov) >> 5;
62 for(i=0; i<n-1; i++) {
63 lbits = *rbits++ << lshift;
64 lbits |= *rbits >> (32 - lshift);
65 if(lbits & *sbits++) ret = 1;
67 lbits = *rbits << lshift;
68 if(lbits & *sbits) ret = 1;
74 mask_collide(int xov, int yov, struct shape *r, struct shape *s)
77 uint32_t *rbits, *sbits;
80 ry = r->h - yov; sy = 0;
81 rbits = r->mask + (r->h - yov) * r->mw;
84 ry = 0; sy = s->h + yov;
86 sbits = s->mask + (s->h + yov) * s->mw;
89 for(y=0; y<abs(yov); y++) {
90 if(line_collide(xov, r, rbits, s, sbits)) return 1;
91 rbits += r->mw; sbits += s->mw;
98 collide(int xdiff, int ydiff, struct shape *r, struct shape *s)
102 if(xdiff >= 0) xov = max(min(r->w-xdiff, s->w), 0);
103 else xov = min(-min(s->w+xdiff, r->w), 0);
105 if(ydiff >= 0) yov = max(min(r->h-ydiff, s->h), 0);
106 else yov = min(-min(s->h+ydiff, r->h), 0);
108 if(xov == 0 || yov == 0) return 0; // bboxes hit?
109 else return mask_collide(xov, yov, r, s);
113 pixel_collide(unsigned int xoff, unsigned int yoff, struct shape *r)
117 if(xoff >= r->w || yoff >= r->h) return 0;
119 pmask = 0x80000000 >> (xoff&0x1f);
120 return r->mask[(yoff*r->mw) + (xoff>>5)] & pmask;