viewer: export getWallHideState from systems/wall/wall-cutout

[esteban685]

Request: export getWallHideState(wallNode, wallMesh, wallMode, cameraDir) from @pascal-app/viewer (currently a private function in systems/wall/wall-cutout.js; only WallCutout is exported).

Use case: a host application rendering overlays/companion layers inside <Viewer>'s children seam needs to respect the see-through wall states that WallCutout computes per camera move (visible / translucent / invisible). Today the only options are (a) re-implementing the facing-vs-camera dot product — which will drift from your semantics when they evolve — or (b) inferring the state from the currently assigned material variant's transparent flag, which is fragile against internal reshuffles.

Exporting the pure helper (it takes its inputs explicitly and touches no module state) would let hosts stay in lockstep with your hide-state semantics without forking. Happy to PR it if that's preferred.

Context: @pascal-app/viewer 0.9.2, host app mounting custom layers via Viewer children.

🤖 Generated with Claude Code

[Aymericr]

Good ask, and the reasoning is right — inferring visibility from the material variant's transparent flag conflates translucent mode with a hidden wall, and a re-derived facing test drifts the moment we change the rule.

Done in #576. getWallHideState is now exported from @pascal-app/viewer with the signature you proposed, plus the WallMode type it takes (previously the parameter was a bare string). No behavior change — the predicate was already pure, so it's an export, not a refactor. I added tests pinning the semantics now that they're public API: up always shows, down always hides, cutaway hides the near exterior face and both-sides-interior walls, keeps both-sides-exterior walls visible from either side.

Thanks for the offer to PR it — it was a three-line change so I took it, but the write-up in the issue is what made it a five-minute decision instead of a discussion. More of those, please.

[Aymericr]

Shipped — #576 is merged to main.

import { getWallHideState, type WallMode } from '@pascal-app/viewer'

const hidden = getWallHideState(wallNode, wallMesh, wallMode, cameraDirection)

WallMode is exported alongside it so you don't have to re-declare the union. The function is pure — it reads only its arguments and the mesh's world direction — so it's safe to call outside the render loop. I added wall-hide-state.test.ts pinning the five behaviors it now guarantees publicly (up always shows, down always hides, and the three cutaway facing cases), since these are API surface now rather than an internal detail.

It'll be in the next @pascal-app/viewer beta.