Function pick

Tests the picking ray through (ndcX, ndcY) against every candidate and returns the hits, nearest first (§71).

const hits: PickHit[] = [];                 // reused
pick(camera, ndcX, ndcY, pickables, hits);
if (hits.length > 0) select(hits[0].node);  // hits[0] is the front-most
Copy

Each candidate is tested in its own local space — the ray is transformed by the inverse of the node's world matrix, so a rotated or non-uniformly scaled box is tested exactly rather than as an inflated world-space AABB (see the module header). World matrices are resolved on demand per candidate, so the result is correct mid-frame without a preceding resolve pass.

Every hit reports the entry point: the first intersection at or after the ray origin. A ray that starts inside a box hits it at distance 0; a box entirely behind the near plane is not hit at all. out is truncated to the number of hits, so an empty array means nothing was picked.

Skipped rather than reported, in both cases because no meaningful answer exists: a candidate with an empty or inverted box (the min = +Infinity convention of an empty geometry), and one whose world matrix is singular (a zero scale somewhere up its chain), which cannot be inverted and describes a node collapsed to nothing. A degenerate camera whose ray has no direction yields no hits at all.

node.hitTestMode selects each candidate's strategy — the module header has the full table. In brief: null (the default) refines the box hit by whatever the candidate carries; "bounds", "geometry" and "pixel" force one strategy, the latter two throwing FourError (INVALID_APPLICATION_STATE, §85) when their box is hit but the candidate carries no Pickable.triangles / Pickable.alphaMask; and a "gpu" candidate is never tested here at all. A geometry-refined hit reports the distance and point of the triangle actually under the pointer, not the box entry.

Allocation follows plan D7: pass out and the steady state allocates nothing — the hits are pooled per array and rewritten in place, which is why a hit (and its point) read after the next pick into the same array describes a different intersection. Omitting out allocates a fresh array for authoring convenience.

depthRange is forwarded to createPickRay; see there.