Function ecs_get_depth 

pub unsafe extern "C" fn ecs_get_depth(
    world: *const ecs_world_t,
    entity: ecs_entity_t,
    rel: ecs_entity_t,
) -> i32

Return depth for entity in tree for the specified relationship. Depth is determined by counting the number of targets encountered while traversing up the relationship tree for rel. Only acyclic relationships are supported.

@param world The world. @param entity The entity. @param rel The relationship. @return The depth of the entity in the tree.