ReadonlyndcNormalized device X, in [-1, 1].
ReadonlyndcNormalized device Y, in [-1, 1], +Y up (§7a).
ReadonlyviewportThe view the pick is against (§48) — the same Viewport object the last
PickingService.update drew. The id buffer holds exactly one
view's pass, so a request naming any other viewport is refused (§85)
rather than answered from the wrong picture.
One pick query against a PickingService (§71; RFC 0005).
ndcX/ndcYare the same normalized device coordinate@fourjs/input's ray pick takes:[-1, 1]on both axes, +Y up (§7a), so(-1, -1)is the bottom-left of the viewport. Converting a pointer position in CSS pixels into NDC is the pointer source's job (§72), not this API's.