This function is used to create an animator system.
void dg_sys_animator(dg_entity_t *entity, dg_window_t *w, dg_array_t **entities, sfTime dt);
dg_scene_add_sys(v->scene_game, dg_system_create(&dg_sys_animator));
void dg_sys_animator(dg_entity_t *entity, dg_window_t *w,
dg_array_t **entities, sfTime dt)
{
dg_animator_t *animator = (dg_animator_t *)
(dg_entity_get_component(entity, "animator"));
sfSprite *sprite = (sfSprite *)(dg_entity_get_component(entity, "sprite"));
if (!dg_system_require(entity, 2, "animator", "sprite"))
return;
dg_animator_update_sprite(animator, sprite, dt.microseconds);
}