9 SDL_Surface *load_image(char *filename);
12 // 2 sets of sprites, sorted by position
13 static Sprite **sprites[2] = { NULL, NULL };
15 // which set are we using?
18 // size of squares into which sprites are sorted.
19 static int grid_size = 0;
21 // screen size in grid squares.
22 static int gw = 0, gh = 0;
24 // lists of free sprites, by type.
25 Sprite *free_sprites[N_TYPES];
33 uint32_t bits = 0, bit, *p;
35 if(s->image->format->BytesPerPixel != 2) {
36 fprintf(stderr, "get_shape(): not a 16-bit image!\n");
40 s->w = s->image->w; s->h = s->image->h;
41 grid_size = max(grid_size, max(s->w, s->h));
42 s->mask_w = ((s->w+31)>>5);
43 s->mask = malloc(s->mask_w*s->h*sizeof(uint32_t));
45 fprintf(stderr, "get_shape(): can't allocate bitmask.\n");
49 SDL_LockSurface(s->image);
50 px = s->image->pixels;
51 transp = s->image->format->colorkey;
53 for(y=0; y<s->image->h; y++) {
55 for(x=0; x<s->image->w; x++) {
56 if(!bit) { bits = 0; bit = 0x80000000; }
57 if(*px++ != transp) { bits |= bit; }
59 if(!bit || x == s->image->w - 1) { *(p++) = bits; }
61 px = (uint16_t *) ((uint8_t *) px + s->image->pitch - 2*s->image->w);
63 SDL_UnlockSurface(s->image);
68 load_sprite(Sprite *s, char *filename)
70 s->image = load_image(filename);
71 if(s->image) get_shape(s);
88 grid_size = grid_size * 3 / 2;
89 gw = (XSIZE-1 + 2*grid_size) / grid_size;
90 gh = (YSIZE-1 + 2*grid_size) / grid_size;
92 sprites[0] = malloc(2 * gw * gh * sizeof(Sprite *));
93 sprites[1] = (void *)sprites[0] + gw * gh * sizeof(Sprite *);
95 fprintf(stderr, "init_sprites(): can't allocate grid squares.\n");
98 memset(sprites[0], 0, 2 * gw * gh * sizeof(Sprite *));
102 static inline Sprite **
103 square(int x, int y, int set)
105 int b = (x+grid_size)/grid_size + gw*((y+grid_size)/grid_size);
106 return &sprites[set][b];
110 add_sprite(Sprite *s)
112 insert_sprite(square(s->x, s->y, set), s);
116 move_sprite(Sprite *s)
119 s->x += (s->dx - screendx)*t_frame;
120 s->y += (s->dy - screendy)*t_frame;
124 sort_sprite(Sprite *s)
126 // clip it, or sort it into the other set of sprites.
127 if(s->x + s->w < 0 || s->x >= XSIZE
128 || s->y + s->h < 0 || s->y >= YSIZE) {
129 insert_sprite(&free_sprites[s->type], s);
131 } else insert_sprite(square(s->x, s->y, 1-set), s);
140 // Move all the sprites (position and set)
141 for(sq=0; sq<gw*gh; sq++) {
142 head=&sprites[set][sq];
144 Sprite *s = remove_sprite(head);
145 move_sprite(s); sort_sprite(s);
148 set = 1-set; // switch to other set of sprites.
153 line_collide(int xov, unsigned bit, uint32_t *amask, uint32_t *bmask)
155 int i, words = (xov-1) >> 5;
158 for(i=0; i<words; i++) {
159 abits = *amask++ << bit;
160 abits |= *amask >> (32-bit);
161 if(abits & *bmask++) return true;
163 abits = *amask << bit;
164 if(abits & *bmask) return true;
170 mask_collide(int xov, int yov, Sprite *a, Sprite *b)
173 int xoffset = a->w - xov;
174 int word = xoffset >> 5, bit = xoffset & 31;
175 uint32_t *amask = a->mask, *bmask = b->mask;
178 amask = a->mask + ((a->h - yov) * a->mask_w) + word;
183 bmask = b->mask + ((b->h - yov) * b->mask_w) + word;
186 for(y=0; y<yov; y++) {
187 if(line_collide(xov, bit, amask, bmask)) return 1;
188 amask += a->mask_w; bmask += b->mask_w;
195 collide(Sprite *a, Sprite *b)
197 int dx, dy, xov, yov;
199 if(b->x < a->x) { Sprite *tmp = a; a = b; b = tmp; }
204 xov = max(min(a->w - dx, b->w), 0);
206 if(dy >= 0) yov = max(min(a->h - dy, b->h), 0);
207 else yov = -max(min(a->h - -dy, b->h), 0);
209 if(xov == 0 || yov == 0) return false;
210 else return mask_collide(xov, yov, a, b);
214 hit_in_square(Sprite *r, Sprite *s)
216 for(; r; r=r->next) {
217 if(collide(r, s)) return true;
228 l = (s->x + grid_size) / grid_size;
229 r = (s->x + s->w + grid_size) / grid_size;
230 t = (s->y + grid_size) / grid_size;
231 b = (s->y + s->h + grid_size) / grid_size;
232 sq = &sprites[set][l + t*gw];
234 if(hit_in_square(*sq, s)) return true;
235 if(l > 0 && hit_in_square(*(sq-1), s)) return true;
236 if(t > 0 && hit_in_square(*(sq-gw), s)) return true;
237 if(l > 0 && t > 0 && hit_in_square(*(sq-1-gw), s)) return true;
240 if(hit_in_square(*(sq+1), s)) return true;
241 if(t > 0 && hit_in_square(*(sq+1-gw), s)) return true;
244 if(hit_in_square(*(sq+gw), s)) return true;
245 if(l > 0 && hit_in_square(*(sq-1+gw), s)) return true;
247 if(r > l && b > t && hit_in_square(*(sq+1+gw), s)) return true;
252 pixel_collide(Sprite *s, int x, int y)
256 if(x < s->x || y < s->y || x >= s->x + s->w || y >= s->y + s->h) return 0;
258 x -= s->x; y -= s->y;
259 pmask = 0x80000000 >> (x&0x1f);
260 return s->mask[(y*s->mask_w) + (x>>5)] & pmask;
264 pixel_hit_in_square(Sprite *r, float x, float y)
266 for(; r; r=r->next) {
267 if(pixel_collide(r, x, y)) return 1;
273 pixel_collides(float x, float y)
278 l = (x + grid_size) / grid_size; t = (y + grid_size) / grid_size;
279 sq = &sprites[set][l + t*gw];
280 if(pixel_hit_in_square(*sq, x, y)) return true;
281 if(l > 0 && pixel_hit_in_square(*(sq-1), x, y)) return true;
282 if(t > 0 && pixel_hit_in_square(*(sq-gw), x, y)) return true;
283 if(l > 0 && t > 0 && pixel_hit_in_square(*(sq-1-gw), x, y)) return true;