#define SPRITE(x) ((Sprite *) (x))
-#define BASE_SPRITE 0
-#define SHIP_SPRITE 1
-#define ROCK_SPRITE 2
+#define BASE 0
+#define SHIP 1
+#define ROCK 2
#define N_TYPES 3
struct sprite {
Sprite *free_sprites[N_TYPES]; // lists of free sprites, by type.
+void do_collision(Sprite *a, Sprite *b);
+void collisions(void);
+
void init_sprites(void);
void add_sprite(Sprite *s);
void move_sprite(Sprite *s);