feat(simulation): voxel-tier mid-scale relief — navigable hills (T-1081)
The voxel tier read flat (the D-245 "0–3 m, no hills to navigate by" bug): family generators set elevation from elev_q at a compressed scale plus only ±4 m micro-scatter, and detail-scatter's mid-scale relief (D-243 §2) only ever reached the district tier (elev_q), never per-voxel elevation_m. - detail_scatter.rs: extract the enveloped-fBm core; add `voxel_relief` at the 0.25–2 km octave band (vs the district 4–40 km band). - voxel.rs: add the mid-scale relief post-dispatch in derive_voxel_column, body-global SeedDomain::VoxelRelief seed (position-keyed), f64 truncated to integer metres (D-010). Envelope = slope_q*3 + elev_q — the coarse heightmap gives slope_q ≈ 0 even on high ground (Arbour max 13), so elevation must drive ruggedness. Flat families only (Alluvial/Lava/BraidedDelta/Dune/Meander); the dramatic families already carry strong internal relief and WaterBody stays at sea level. - seed.rs: SeedDomain::VoxelRelief (D-224 domain separation). - believability.rs: new `contrast.voxel_relief_m` metric — mean within-district elevation range over a 2 km transect (a single 64 m sample chunk is narrower than the relief band) + a "voxel relief" criterion. Arbour @ yolo: voxel relief 5 m → 59 m, 6/8 → 7/8 criteria (remaining fail = the Q-123 vegetation-denominator item). Edict 59 m. Golden regenerated; 1586 lib tests + believability harness (determinism) pass; clippy -D warnings clean. D-239 amended (T-1081); Q-123 item 4 updated. Deferred to Q-123/follow-up: the provisional span + threshold, and a per-body hypsometric absolute-elevation model. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This commit is contained in:
Claude Opus 4.8
@@ -67,6 +67,11 @@ const WATER_PRESENCE_Q: i32 = 10;
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const VOXEL_SAMPLE_DISTRICTS: usize = 64;
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/// Stride over a district's representative 64 m chunk (8 → an 8×8 = 64-voxel sample).
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const VOXEL_SAMPLE_STRIDE: usize = 8;
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/// Chunk offsets within a district (×64 m ⇒ 128 m … 1920 m) for the mid-scale relief
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/// transect (T-1081) — samples the elevation range a character crosses over the
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/// district's ~2 km span (the voxel-relief band), which the single 64 m sample chunk
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/// is too narrow to register.
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const RELIEF_TRANSECT_CHUNK_OFFSETS: [i32; 6] = [2, 8, 14, 20, 26, 30];
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// ---------------------------------------------------------------------------
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// Report types (serde — golden-snapshot-able)
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@@ -101,6 +106,12 @@ pub struct ContrastMetrics {
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pub vegetation_classes: usize,
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/// Distinct voxel `TerrainMaterial` values across the voxel sample.
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pub terrain_materials: usize,
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/// Mean within-district voxel elevation *range* (metres) across a district-spanning
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/// transect of the sampled land districts (T-1081). The walkable-relief screen:
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/// near 0 on flat terrain (the "0–3 m, no hills" symptom), tens of metres once the
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/// voxel tier carries mid-scale relief. Measured over the 0.25–2 km band a character
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/// traverses — not the single 64 m sample chunk, which is too narrow to register it.
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pub voxel_relief_m: i32,
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}
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/// Coherence checks — does the world render as a *caused* place? Pass/fail counts
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@@ -171,6 +182,7 @@ pub fn analyze(
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.map(|d| format!("{:?}", d.vegetation_class)),
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),
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terrain_materials: 0, // filled from the voxel sample below
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voxel_relief_m: 0, // filled from the relief transect below
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};
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// ── Voxel-derived metrics over a deterministic seeded spread of districts ──
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@@ -181,6 +193,9 @@ pub fn analyze(
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let mut terrain_set: BTreeSet<String> = BTreeSet::new();
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let mut coh = CoherenceMetrics::default();
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let mut sampled = 0usize;
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// Mid-scale relief accumulators (T-1081): sum of per-district transect ranges over
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// land districts, and the count contributing, → mean within-district relief.
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let (mut relief_range_sum, mut relief_district_count) = (0i64, 0i64);
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let keys: Vec<DistrictPos> = districts.keys().copied().collect();
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for idx in sample_indices(world_seed, keys.len(), VOXEL_SAMPLE_DISTRICTS) {
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@@ -243,8 +258,43 @@ pub fn analyze(
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coh.drainage_monotonic += 1;
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}
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}
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// Mid-scale relief transect (T-1081): the dry-ground elevation range across the
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// district's ~2 km span — where the voxel tier's mid-scale relief lives. The
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// single 64 m sample chunk above is narrower than the relief's 0.25–2 km band,
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// so it would read flat even on rolling terrain; this transect is the screen.
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// Only land-dominant districts count (≥3 of 6 transect points dry) — coastal
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// districts with one stray dry point would otherwise contribute a 0 range and
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// bias the mean toward "flat" on an ocean world (a measurement artifact, not
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// flat land).
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let (mut relief_lo, mut relief_hi, mut relief_dry) = (i32::MAX, i32::MIN, 0i32);
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for &co in &RELIEF_TRANSECT_CHUNK_OFFSETS {
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let cpos = (
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dp.0 * CHUNKS_PER_DISTRICT + co,
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dp.1 * CHUNKS_PER_DISTRICT + co,
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);
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let cctx = derive_chunk_context(world_seed, body_id, prof, cpos, None);
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let tx = cpos.0 * CHUNK_M + CHUNK_M / 2;
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let ty = cpos.1 * CHUNK_M + CHUNK_M / 2;
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let col = derive_voxel_column(world_seed, body_id, prof, &cctx, tx, ty);
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if col.water == Water::Dry {
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relief_lo = relief_lo.min(col.elevation_m);
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relief_hi = relief_hi.max(col.elevation_m);
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relief_dry += 1;
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}
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}
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if relief_dry >= 3 {
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relief_range_sum += (relief_hi - relief_lo) as i64;
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relief_district_count += 1;
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}
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}
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let voxel_relief_m = if relief_district_count > 0 {
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(relief_range_sum / relief_district_count) as i32
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} else {
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0
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};
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BelievabilityReport {
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body_id: body_id.to_string(),
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world_seed,
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@@ -252,6 +302,7 @@ pub fn analyze(
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voxel_sampled_districts: sampled,
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contrast: ContrastMetrics {
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terrain_materials: terrain_set.len(),
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voxel_relief_m,
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..contrast_scalar
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},
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coherence: coh,
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@@ -280,6 +331,11 @@ pub fn evaluate_criteria(r: &BelievabilityReport) -> Vec<Criterion> {
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pass: c.elev_q.spread() >= 10,
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detail: format!("elev_q spread={}", c.elev_q.spread()),
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},
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Criterion {
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name: "voxel relief",
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pass: c.voxel_relief_m >= 8,
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detail: format!("mean within-district relief {} m", c.voxel_relief_m),
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},
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Criterion {
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name: "morphology variety",
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pass: c.morphology_zones >= 2,
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@@ -24,6 +24,12 @@ use crate::seed::splitmix64;
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/// coarsest (~33 km) the heightmap itself carries the shape.
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const OCTAVE_WAVELENGTHS_M: [f64; 4] = [32_768.0, 16_384.0, 8_192.0, 4_096.0];
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/// Voxel-tier octave wavelengths in metres — the ≈0.25–2 km band that the
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/// district-tier [`terrain_detail`] (4–40 km) is too coarse to carry and the
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/// per-voxel scatter (<64 m) is too fine to reach. This is the [`voxel_relief`]
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/// band: the rolling/ridged hills a *walking character* navigates by (T-1081).
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const VOXEL_OCTAVE_WAVELENGTHS_M: [f64; 4] = [2_048.0, 1_024.0, 512.0, 256.0];
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/// Deterministic lattice value in `[-1, 1)` for an integer noise cell.
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#[inline]
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fn lattice(seed: u64, ix: i64, iy: i64) -> f64 {
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@@ -64,6 +70,40 @@ fn value_noise(seed: u64, wx: f64, wy: f64, wavelength_m: f64) -> f64 {
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/// Returns roughly `[-envelope, +envelope]`, smaller and smoother as `ruggedness`
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/// drops toward 0 (gentle flats), larger and ridged as it rises toward 1.
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pub fn terrain_detail(seed: u64, wx: f64, wy: f64, envelope: f64, ruggedness: f64) -> f64 {
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enveloped_fbm(seed, wx, wy, envelope, ruggedness, &OCTAVE_WAVELENGTHS_M)
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}
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/// The voxel-tier mid-scale relief perturbation in `[0,1]`-normalized units
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/// (multiply by the body's relief span for metres) — the ≈0.25–2 km rolling/ridged
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/// hills a walking character navigates by (T-1081). Identical envelope/ruggedness
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/// contract as [`terrain_detail`]; only the octave band differs
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/// ([`VOXEL_OCTAVE_WAVELENGTHS_M`] vs the district [`OCTAVE_WAVELENGTHS_M`]).
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///
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/// Seed must be **body-global** (constant across the body) — the position
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/// `(wx, wy)` carries the variation. A per-voxel seed would make every voxel a
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/// fresh lattice (white noise, not smooth hills).
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pub fn voxel_relief(seed: u64, wx: f64, wy: f64, envelope: f64, ruggedness: f64) -> f64 {
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enveloped_fbm(
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seed,
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wx,
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wy,
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envelope,
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ruggedness,
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&VOXEL_OCTAVE_WAVELENGTHS_M,
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)
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}
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/// Shared adaptive-fBm core for [`terrain_detail`] and [`voxel_relief`] — the only
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/// difference between the two tiers is the octave wavelength band. Returns the
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/// enveloped, ruggedness-modulated perturbation (roughly `[-envelope, +envelope]`).
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fn enveloped_fbm(
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seed: u64,
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wx: f64,
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wy: f64,
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envelope: f64,
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ruggedness: f64,
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wavelengths: &[f64],
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) -> f64 {
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let env = envelope.clamp(0.0, 1.0);
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let rug = ruggedness.clamp(0.0, 1.0);
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if env == 0.0 {
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@@ -73,7 +113,7 @@ pub fn terrain_detail(seed: u64, wx: f64, wy: f64, envelope: f64, ruggedness: f6
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let mut sum = 0.0;
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let mut amp = 1.0;
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let mut norm = 0.0;
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for (i, &wl) in OCTAVE_WAVELENGTHS_M.iter().enumerate() {
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for (i, &wl) in wavelengths.iter().enumerate() {
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let mut n = value_noise(
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seed.wrapping_add((i as u64).wrapping_mul(0x1000)),
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wx,
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@@ -159,4 +199,38 @@ mod tests {
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(base - near).abs()
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);
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}
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// ── voxel_relief (T-1081): same contract, sub-district band ──────────────
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#[test]
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fn voxel_relief_deterministic_and_bounded() {
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let a = voxel_relief(42, 12_345.0, -6_789.0, 0.6, 0.5);
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let b = voxel_relief(42, 12_345.0, -6_789.0, 0.6, 0.5);
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assert_eq!(a, b);
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// Same envelope rule + amplitude ceiling as terrain_detail.
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assert_eq!(voxel_relief(7, 1_000.0, 2_000.0, 0.0, 1.0), 0.0);
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for i in 0..400 {
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let v = voxel_relief(99, i as f64 * 137.0, i as f64 * -91.0, 0.5, 1.0);
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assert!(v.abs() <= 0.5 + 1e-9, "v={v} exceeded envelope at {i}");
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}
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}
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#[test]
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fn voxel_relief_varies_at_sub_district_scale() {
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// The voxel band must produce DISTINCT relief within a single 2 km district —
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// exactly the variation terrain_detail's 4–40 km band cannot carry, and the
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// flatness T-1081 fixes. Body-global seed; position carries the variation. Steps
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// are deliberately non-aligned with the octave wavelengths to avoid aliasing.
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let seed = 1234;
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let vals: Vec<f64> = (0..16)
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.map(|i| voxel_relief(seed, i as f64 * 137.0, i as f64 * 89.0, 0.7, 0.6))
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.collect();
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let min = vals.iter().cloned().fold(f64::INFINITY, f64::min);
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let max = vals.iter().cloned().fold(f64::NEG_INFINITY, f64::max);
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assert!(
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max - min > 0.1,
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"voxel relief is near-flat across a district: range {}",
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max - min
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);
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}
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}
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@@ -333,6 +333,15 @@ fn zone_to_family(zone: &MorphologyZone) -> MorphologyFamily {
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/// ## Returns
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///
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/// A fully derived `VoxelColumn` with all D-228 axes populated.
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/// T-1081: the metre span of the voxel-tier mid-scale relief field — the amplitude
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/// ceiling for the ≈0.25–2 km rolling/ridged hills added to the family base
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/// elevation. Actual relief at a voxel is `voxel_relief(...) * SPAN`, which the
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/// envelope (district ruggedness) scales down on gentle terrain, so this is the
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/// steep-terrain ceiling, not a uniform amplitude. Provisional — tuned against the
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/// believability probe (T-1079) like the moisture gradient; per-body *absolute*
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/// elevation span is a later refinement (the T-1080 climate-fields lineage).
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const VOXEL_RELIEF_SPAN_M: i32 = 300;
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pub fn derive_voxel_column(
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world_seed: u64,
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body_id: &str,
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@@ -427,6 +436,58 @@ pub fn derive_voxel_column(
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}
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};
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// ── 3b. Voxel-tier mid-scale relief (T-1081, D-227 / D-243 §2) ────────
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// The family generators set a coarse district-derived base elevation plus only
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// ±4 m of per-voxel micro-scatter, leaving the walkable surface near-flat — no
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// hills or landmarks to navigate by (the T-1081 symptom). Add the mid-scale
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// (≈0.25–2 km) rolling/ridged relief the district→voxel seam does not otherwise
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// reach (D-243 §2): detail-scatter enveloped by district ruggedness (slope_q) so
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// an authored plain stays flat and rugged terrain gains real relief. The relief
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// field is body-global (SeedDomain::VoxelRelief, position-keyed); the f64
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// perturbation is truncated to integer metres before assignment (D-010,
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// truncate-before-decision — the same sanctioned f64 path as the domain warp).
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//
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// Skipped for the WaterBody family: open ocean / lake / tidal-flat surfaces stay
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// at sea level (elevation 0). River channels inside the land families ride up
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// with their banks — value noise is smooth at 1 m steps, so a channel voxel and
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// its bank get near-identical relief and the family's relative channel cut holds.
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// Only the FLAT families take the mid-scale relief. The dramatic families
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// (CliffCoast / FjordWall / IncisedGorge) already generate strong internal relief
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// from their own geometry — layering a position-varying field over them would warp
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// those features (e.g. drown a gorge's wall-to-floor drop under a relief swell).
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// WaterBody stays at sea level. The flat families are the ones that read flat and
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// need invented relief; their only feature is a 3–15 m channel, narrow enough that
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// the smooth relief shifts it bodily with its banks.
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let takes_mid_scale_relief = matches!(
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family,
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MorphologyFamily::AlluvialPlain
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| MorphologyFamily::LavaField
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| MorphologyFamily::BraidedDelta
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| MorphologyFamily::DuneStrand
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| MorphologyFamily::MeanderReach
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);
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if takes_mid_scale_relief {
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let relief_seed = SeedChain::for_body(world_seed, body_id)
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.derive(SeedDomain::VoxelRelief, 0)
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.seed();
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// Relief envelope (T-1081): the coarse heightmap (~40–78 km/px) carries almost
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// no slope at this tier (slope_q tops out near 0.1 on a real body), so gating on
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// slope_q alone would kill the invented relief everywhere. Combine slope with
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// elevation — high ground reads rugged, coastal lowlands stay gentle — so
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// detail-scatter raises hills where the body has high terrain and keeps flats
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// soft. (Tectonic-class ridge sharpening is a later refinement.)
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let signal = (district_eff.slope_q * 3 + district_eff.elev_q).clamp(0, 100) as f64 / 100.0;
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let relief = crate::atlas::detail_scatter::voxel_relief(
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relief_seed,
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voxel_x as f64,
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voxel_y as f64,
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signal,
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signal,
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);
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let relief_m = (relief * VOXEL_RELIEF_SPAN_M as f64) as i32; // truncate (D-010)
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column.elevation_m = (column.elevation_m + relief_m).max(0);
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}
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// ── 4. Seasonal cover overlay (D-239 §3, T-1030) ──────────────────────
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// Applied AFTER family dispatch: the 8 family generators produce the base
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// axes (terrain/water/vegetation/elevation); cover is a separate orthogonal
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@@ -2235,6 +2296,86 @@ mod tests {
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assert_eq!(a, b);
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}
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// ── Voxel-tier mid-scale relief (T-1081) ─────────────────────────────────
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#[test]
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fn voxel_relief_gives_rugged_land_navigable_hills() {
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// T-1081: a rugged land district must produce mid-scale relief across a ~2 km
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// span far exceeding the ±4 m micro-scatter (the "flat 0–3 m, no hills" symptom).
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let mut district = alluvial_district();
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district.slope_q = 60; // rugged → relief headroom
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let chunk = alluvial_chunk(&district);
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let mut elevs = Vec::new();
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for i in 0..12 {
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let p = i * 256; // step across the voxel-relief band (0.25–2 km)
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let col = derive_voxel_column(42, "GJ1c", &district, &chunk, p, p);
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if col.water == Water::Dry {
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elevs.push(col.elevation_m);
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}
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}
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assert!(elevs.len() >= 4, "expected mostly dry-land samples");
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let min = *elevs.iter().min().unwrap();
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let max = *elevs.iter().max().unwrap();
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assert!(
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max - min > 20,
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"rugged district should have navigable mid-scale relief, got {min}..{max} m"
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);
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}
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#[test]
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fn voxel_relief_respects_low_flat_envelope() {
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// No slope AND no elevation → no terrain signal → no invented relief (the
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// envelope rule: don't sprout hills on a flat sea-level plain). Elevation stays
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// the family base (elev_q/2 = 0 m) plus only the ±4 m micro-scatter / channel cut.
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let mut district = alluvial_district();
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district.slope_q = 0;
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district.elev_q = 0;
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let chunk = alluvial_chunk(&district);
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for i in 0..12 {
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let p = i * 256;
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let col = derive_voxel_column(42, "GJ1c", &district, &chunk, p, p);
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assert!(
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col.elevation_m <= 4,
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"low-flat district gained mid-scale relief: {} m",
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col.elevation_m
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);
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}
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}
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#[test]
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fn voxel_relief_from_elevation_even_with_zero_slope() {
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// The T-1081 root cause: the coarse heightmap gives slope_q ≈ 0 even on high
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// terrain, so ELEVATION must drive the relief envelope. A high district with
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// slope_q == 0 must still gain navigable hills (else high ground reads flat).
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let mut district = alluvial_district();
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district.slope_q = 0;
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district.elev_q = 90; // high ground, coarse-heightmap-flat
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||||
let chunk = alluvial_chunk(&district);
|
||||
let mut elevs = Vec::new();
|
||||
for i in 0..12 {
|
||||
let p = i * 256;
|
||||
let col = derive_voxel_column(42, "GJ1c", &district, &chunk, p, p);
|
||||
if col.water == Water::Dry {
|
||||
elevs.push(col.elevation_m);
|
||||
}
|
||||
}
|
||||
let range = elevs.iter().max().unwrap() - elevs.iter().min().unwrap();
|
||||
assert!(
|
||||
range > 20,
|
||||
"high terrain must gain relief despite slope_q=0, got range {range} m"
|
||||
);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn voxel_relief_is_deterministic() {
|
||||
let mut district = alluvial_district();
|
||||
district.slope_q = 50;
|
||||
let chunk = alluvial_chunk(&district);
|
||||
let a = derive_voxel_column(42, "GJ1c", &district, &chunk, 777, 1234);
|
||||
let b = derive_voxel_column(42, "GJ1c", &district, &chunk, 777, 1234);
|
||||
assert_eq!(a.elevation_m, b.elevation_m);
|
||||
}
|
||||
|
||||
// -----------------------------------------------------------------------
|
||||
// TerrainMaterial discriminant pins
|
||||
// -----------------------------------------------------------------------
|
||||
|
||||
@@ -110,6 +110,11 @@ pub enum SeedDomain {
|
||||
/// so the per-cluster cover hash can never collide with the per-voxel terrain
|
||||
/// stream — domain separation guarantees no freeze-to-terrain correlation.
|
||||
Cover = 10,
|
||||
/// Voxel-tier mid-scale relief noise field (T-1081, D-243 §2). A body-global,
|
||||
/// position-keyed elevation perturbation at sub-district wavelengths (≈0.25–2 km),
|
||||
/// keyed by a single constant id (one field per body). Distinct domain so the
|
||||
/// relief lattice can never correlate with the per-voxel terrain or cover streams.
|
||||
VoxelRelief = 11,
|
||||
}
|
||||
|
||||
/// A position in the deterministic seed tree (D-224).
|
||||
|
||||
Reference in New Issue
Block a user