rev 3 of the curve redesign. The developer's verdict on the 01 baseline was that the
LOWLANDS ARE GOOD; the fault is the terracing above them. So this adds a second curve
mode that preserves the low plain bit-for-bit and replaces everything above the flood
line with one smooth monotone climb.
Core/ContinuousCurve — piecewise, and the pieces have different loyalties:
- at/below sea: identity, as ever.
- above sea to K2: DELEGATES to HeightCurve's own toe+red branches. Not "equivalent" —
the same code path, so the same floats. Oracle (d) holds it to that.
- above the ceiling: a Fritsch-Carlson (PCHIP) monotone spline to the 420 m cap,
C1-joined to the red band's exit slope. Monotone by construction for any ordered
control points, which retires the 24-corner sweep; a 10k strict-increase sample runs
per seed anyway, because "cannot fail" is worth a millisecond.
- Build() REFUSES rather than degrades: a ceiling near the old bench, a drama that folds
the summit under its own onset, control-point secants that are not strictly increasing
(the no-magnet rule, enforced rather than hoped for).
Only BENCH_*/PLATEAU_* are dropped. SEA/ORANGE_CEIL/RED_CEIL survive because they are
the storm-ladder FLOOD TIERS and they live inside the preserved lowland; PEAK_CAP and
the per-seed spikeMax normalization survive as the summit.
Shelf detail is forced off in continuous mode: the flat benches it de-slabbed no longer
exist, and painting noise on the climb now would pre-judge what erosion should carve.
Oracle, all hard checks passing:
- (a1) curve off is bit-identical to Phase 1's dump.
- (a2) staircase mode is bit-identical to TASK 01's dump — the control is provably the
control, not a re-derivation. (CurveBaselineTool is pinned to Staircase so the config
default moving to Continuous cannot drift it.)
- (d) lowlands bit-identical to the staircase over 3.6M cells, every continuous variant,
both seeds. The lifted_WRONG bookend fails it on 1.6M cells, as intended.
- (f) sea identity per CELL, not per count, including 67M cells at 8192.
The finding, measured and recorded in the batch scratch: the massif SHRANK. Land above
100 m goes 14.9% -> 4.8%, above 220 m 4.5% -> 0.6%. A feather sweep to the practical
floor recovers ~1.3 points, so this is structural, not a tuning miss: the staircase's
highland area was an artifact of the bench and plateau acting as magnets, and a curve
with no magnets preserves the raw distribution's bottom-heavy shape. "No terraces" and
"the same land up high" are not both available from curve work alone.
Exploration batch, not convergence. A tuning pass follows once a direction is picked.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DCWNaDZPfTiAy3meGNGgqt
Ports the reference's v5 height curve and shelf-detail passes onto Phase 1's shape
and re-calibrates them against this repo's actual pass-1 distribution. This is the
BASELINE the reshape gets judged against, not the reshape.
Core (engine-free, D-060):
- WorldScale — THE vertical yardstick. One metres/raw number (251), replacing the
prototype's three duplicate M_PER_UNIT constants and ~20 bare literals. The
chunk-height coupling it had there is recorded as a DEFERRED vault decision, not
inherited. RawFromMetres divides, matching the reference bit-for-bit.
- HeightCurve — the 7 bands, the frozen corner-fix blends, the per-seed spike
normalization, the 24-corner monotonicity sweep that throws and refuses.
Identity at and below sea, which everything downstream rests on.
- CurveKnots / CurveAnchors — input knots (measured percentiles) and output anchors
(storm ladder) split apart and both made parameters, so the anchors are A/B-able
without editing source. The reference's shipped knots are kept beside the measured
ones as the fidelity yardstick.
- TerrainDetailPass — micro-relief skin plus the shelf-edge KNOT warp (which slides
K3/K4/K5, not height — that is what keeps monotonicity structural). The crater
exclusion is ported and inert until the carve lands.
Tools:
- Shaping — pass 2a, producing the two height fields. classify is bit-for-bit the
raw pass-1 field; render is curved and detailed. Aliased when the curve is off,
as the reference did. Pass1Result is left immutable so the oracle can compare.
- LandHistogram — the calibration engine AND the diagnostic. The reference shipped
six knot literals and threw the measuring instrument away; this rebuilds it.
- ShapingOracle + CurveBaselineTool — four automatic checks before anything is
looked at, and the batch that runs them.
Measured, not assumed:
- Knots re-measured over a 6-seed / 12.8M-sample pool. They differ from the
reference's by at most 5.6 m of world height, against a 44.7 m per-seed spread —
the pass-1 port is faithful.
- Oracle all pass, including pass 1 bit-identical to Phase 1's own .f32 dump.
- Band shares land on 60/13/10/5/8/3/1 to 0.00 pp.
- Knots hold across map size: the 8K delta (5.8 m) sits inside seed noise.
The finding the histograms deliver: 83% of land ends below 100 m and 96% below
220 m, with the median column at 13 m. That is the share targets doing exactly what
they say, not a bug — and it is the developer's call, which is why nothing here
reshapes it and the palette was deliberately left mis-fitted rather than recalibrated
to disguise it.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DCWNaDZPfTiAy3meGNGgqt
