isDestroyed
Acknowledges physical destruction after close has returned successfully.
The default is valid only for adapters that destroy every target resource synchronously during close. Asynchronous adapters override this nonblocking owner-thread probe and return true only after every color, view, depth, and framebuffer resource has been physically destroyed. A true result is permanent; neither the target nor any of its native resources may become usable again. The device never invokes this method before a successful release request.
Return
whether the target-set lifetime permit may now be released.
Throws
when destruction cannot be queried; ownership and the permit remain retained.