beezm
ed16a7f668
Sized from measurement, not taste-first. |grad raw| at the K3/K4/K5 contours on seed 1375359975 is p50 0.00088 raw/px, so the first try (5 m, 12 undulations/island) displaced the shelf boundary a MEAN of 3.7 px with a roughness ratio of 1.03 -- real, and invisible at map scale. At 12 m and 20/island the boundary moves a mean 8.4 px (bench) / 9.1 px (plateau), roughness ratio 1.09, and the outline grows the notches, coves and peninsulas the sketch asked for. Measured cost at 12 m (A off vs B, same seed): lowland and toe/red bands bit-identical in both pixel count and slope -- the K2 pin holding exactly, as designed. Foothill riser p50 0.681 -> 0.676 m/px, p90 1.445 -> 1.478, max 3.09 -> 3.81. Bench p50 0.21 -> 0.232 (micro-relief included), still buildable. Peaks max identical at 6.55. Safety bound restated from "half the margin to a fixed knot" to 2/3 of the smaller adjacent band, which is the constraint that actually matters: the squeezed band never compresses below a third of its nominal width, so its slope never more than triples. That puts the ceiling at 16.45 m for the v5 knots and leaves the 12 m default real headroom if the gate says "more". Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
88 lines
4.6 KiB
C#
88 lines
4.6 KiB
C#
using Godot;
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/// <summary>
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/// The terrain DETAIL passes (terrain-water task 10) — pure numeric functions
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/// (D-035; a named future C++ candidate, kept standalone):
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///
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/// PASS A — shelf micro-relief: a medium-frequency noise skin (±ShelfReliefAmp,
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/// default 3 m) weighted by shelf-ness, so the compressed shelves get their
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/// rolling texture back while risers and peaks stay untouched.
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///
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/// PASS B — shelf-edge variation: a per-column shift of the shelf/riser KNOT
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/// BLOCK (K3/K4/K5) by a low-frequency noise field, so the boundary where a
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/// shelf meets its riser wanders in and out instead of tracing a clean height
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/// contour — organic notches, coves and peninsulas at the shelf edge.
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///
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/// Both are output-height only; the classify map never sees either of them.
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///
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/// NOTE — what this file deliberately does NOT contain: the task-10 draft's D8
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/// flow routing / accumulation / drainage incision. It shipped, produced the
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/// canonical grid artifact (thousands of straight, disconnected, pooling
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/// scratches along the D8 neighbour directions) and was reverted whole. Rivers
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/// and erosion are Phase C work — a hydraulic-erosion pass over FINAL terrain,
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/// not a per-cell steepest-descent carve on a grid.
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/// </summary>
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public static class TerrainDetailPass
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{
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// The TDTL body version is owned by the format (Core); the pass just stamps it.
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public const ushort VERSION = IslaApocalypse.Core.BlueprintFormat.TDTL_VERSION;
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// Pass A — micro-relief.
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public const float RELIEF_AMP_DEFAULT_M = 3f; // config dial: ShelfReliefAmp (metres)
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public const float RELIEF_FREQ_ISLANDS = 40f; // ~40 undulations per island width (~200 m features)
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public const int RELIEF_SEED_OFFSET = 7409;
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// Pass B — shelf-edge variation. The amplitude is stated in metres of INPUT
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// height (raw × 251): it is how far, in raw-height terms, a shelf boundary
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// contour is displaced — not an output elevation change. What the eye sees is
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// the LATERAL wander, which is that displacement divided by the local raw
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// gradient. Measured on seed 1375359975: |∇raw| at the K3/K4/K5 contours is
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// p50 0.00088 raw/px, so 12 m of input height buys a median peak displacement
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// of ~54 px and a mean of ~8 px along the boundary — coves and notches, which
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// is where the developer's sketch sits. 5 m (the first try) moved the boundary
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// a mean 3.7 px and was invisible at map scale.
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public const float EDGE_AMP_DEFAULT_M = 12f; // config dial: ShelfEdgeVariation (metres of input height)
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public const float EDGE_FREQ_ISLANDS = 20f; // ~410 px wavelength at 8K — coves and notches at the
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public const int EDGE_SEED_OFFSET = 7507; // scale of the sketch, not a fringe of teeth
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// The shift squeezes whichever of the foothill riser / plateau bands it moves
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// into. Bounding it at 2/3 of the smaller band means that band never compresses
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// below a THIRD of its nominal width — i.e. its slope never more than triples,
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// even where peak noise lands on a boundary. That is the real constraint; knot
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// ordering follows from it.
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public const float EDGE_SAFETY_FRACTION = 2f / 3f;
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/// <summary>
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/// The largest per-column knot shift this preset allows: bounded by the band
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/// squeeze above, which also keeps the knot set strictly ordered
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/// (K2 < K3+d, K5+d < K6) with a third of each band to spare. K1/K2/K6 never
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/// move, so the toe, the orange/red bands and the summit spike are
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/// bit-identical whatever the warp does — which is what makes the red-ceiling
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/// floor and the 420 m cap exact rather than statistical.
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/// </summary>
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public static float MaxEdgeShift(CurveKnots k)
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{
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return EDGE_SAFETY_FRACTION * Mathf.Min(k.K3 - k.K2, k.K6 - k.K5);
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}
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/// <summary>
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/// Shelf-ness weight from the RAW input height: 1 mid-shelf, feathering to 0
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/// through the risers (feather extends 30 % of the band half-width past each
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/// shelf edge). Covers both shelves. <paramref name="edgeShift"/> is the same
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/// per-column warp the curve is evaluated with, so the micro-relief skin
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/// follows the shelf wherever pass B has moved its boundary.
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/// </summary>
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public static float ShelfWeight(float raw, CurveKnots k, float edgeShift)
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{
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return Mathf.Max(BandBump(raw, k.K3 + edgeShift, k.K4 + edgeShift),
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BandBump(raw, k.K5 + edgeShift, k.K6));
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}
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private static float BandBump(float h, float lo, float hi)
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{
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float half = (hi - lo) * 0.5f;
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float t = Mathf.Abs(h - (lo + half)) / half; // 0 centre, 1 at band edge
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// full inside 60 % of the band, linear feather to zero at 130 %
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return Mathf.Clamp(1f - (t - 0.6f) / 0.7f, 0f, 1f);
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}
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}
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