Function ecs_observer_init 

pub unsafe extern "C" fn ecs_observer_init(
    world: *mut ecs_world_t,
    desc: *const ecs_observer_desc_t,
) -> ecs_entity_t

Create observer. Observers are like triggers, but can subscribe for multiple terms. An observer only triggers when the source of the event meets all terms.

See the documentation for ecs_observer_desc_t for more details.

@param world The world. @param desc The observer creation parameters.