+void init_sprites(void);
+void add_sprite(Sprite *s);
+void move_sprite(Sprite *s);
+void move_sprites(void);
+
+Sprite *collides(Sprite *s);
+int pixel_collides(float x, float y);
+void load_sprite(Sprite *sprite, char *filename);
+
+void bounce(Sprite *a, Sprite *b);