Fr0zkaandClaude Opus 5.5
6f9bf1ed9f
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_016dhxM43dnWvUu2B5Ph1iG1
34 lines
2.5 KiB
Markdown
34 lines
2.5 KiB
Markdown
# Design49 — flat landing pad at tunnel ends (owner idea, reviewed 2026-11-02)
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Owner: "the end of the tunnel should be flat; flatten the arrival with a fade-out that blends to the surrounding
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density; a cheap stamp applied at arrival, no matter what's there."
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A read-only design review (Claude Opus 5.5, medium effort) of `wip/l134-cave-planner` recommends a **clamp, not a
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lerp**. Each tunnel end gets a level disc at the tunnel's end floor P. Out to a blend radius, the native ground is
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squeezed between two gentle cones (12°) starting at P: a lower one that fills solid, an upper one that carves air.
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Inside the disc the floor is exactly flat; outside it, the slope is never steeper than max(cone, native), with no
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overhang or cliff. The full note is in the session transcript; key points:
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- **Placement:** the last step of `ApplyResolvedStrateComposition`, after the passage composer, on both the native and
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non-native branches. The fill is masked by the tube-only distance (bore stays open). It replaces the landing-chamber
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box, shell and floor-shell special cases that caused L152–L156.
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- **Formula** (metres; ×cos α for 1-Lipschitz). d = max(0, r−R), t = tan α.
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- Fill: `Lo = P − t·d`, `F = max(z−Lo, (Lo−Ds)−z, r−(R+B))`.
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- Air: `Hi = P + t·d`, `A = min(z−Hi, (Hi+H)−z, (R+B)−r)`.
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- Result: `c = max(min(native, max(F, −tubeDist)), A)`.
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- Hard min/max inside R; smooth-min width ramps 0 → 0.5 m over the first metre outside it.
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- Why not lerp: native density saturates at about ±4.125 voxels (`DetailSupremum`), so a lerp makes cliffs and
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films.
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- **Parameters:** α = 12°, R = max(mouthRadius + 1 m, 3 m), B = min(8 m, |Δh_ring|/t + 1 m), H = 3 m, Ds = 1.25 m.
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- **Planner:**
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- P = h(end), with h′ = 0 over the last R.
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- Sample the edge ring; move P into the feasible band or take the next deterministic site.
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- Rewrite route heights inside R+B to the clamped ground.
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- Content-band check including P−tB−Ds and P+tB+H.
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- **Bounds:** the pad influence box goes into the proof bounds, the fallback overlap test, the **tile feature
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bounds** (critical: the composer early-returns on an empty route list) and the proof-miss sampler.
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- **Audits:** new `LandingPadAudit` (flatness ±2 cm, support, headroom, 36 radial blend transects ≤ 15° with one
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crossing) plus negative controls (pad off, 2% tilt, B halved, bore mask removed).
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- **Risks:** caves under pads (connectivity), low ceilings, shaft footprints, island edges and their air gap, liminal
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decks; off-route edges on non-heightfield layers are a metric only.
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