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feat(simulation): cross-district parameter blending at chunk/voxel scale (T-1042)

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Replaces the single-DistrictProfile walking-skeleton restriction so
continuous terrain parameters no longer step at the 2 km district pitch
(D-239 §4/§7/§8). ChunkContext gains secondary: Option<DistrictProfile> +
blend_weight: u8; derive_chunk_context detects a chunk within one chunk of
a district border, looks up the adjacent profile, and integer-blends
meander/channel params on the context. derive_voxel_column integer-blends
elev_q/moisture_q before material selection, reusing the same warp offset so
the seam cannot align with the chunk edge (Cow fast-path keeps interior
chunks bit-identical — golden seed unchanged).

Morphology FAMILY selection is never blended — stays sharp per D-239 §7
(family dispatch reads the primary district only). Climate feathering is the
separate T-1078 path. Adds cross_district_elevation_blend_reduces_seam_step
and cross_district_morphology_family_seams_stay_sharp to the derivation
harness.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This commit is contained in:
jpmschweitzer
2026-06-15 14:05:48 +02:00
co-authored by Claude Opus 4.8
parent 030e0907bc
commit 32010cc498
3 changed files with 529 additions and 96 deletions
Download Patch File Download Diff File Expand all files Collapse all files
server/src/atlas/chunk_context.rs
+181 -28
View File
@@ -25,6 +25,18 @@
//! anchors in continuous world coordinates — never from the world origin and
//! never folded into the 64 m chunk frame.
//!
//! ## Cross-district blending (T-1042, D-239 §4/§7)
//!
//! Chunks within one chunk (64 m) of a district boundary carry a `secondary`
//! `DistrictProfile` and a `blend_weight` (255 = 100% primary; 128 = 50-50 blend).
//! The blend applies to **continuous positional params only**: `meander_wavelength_m`,
//! `channel_width_m`, `meander_phase` (all pre-blended here on the context) and
//! `elev_q` / `moisture_q` (blended in `derive_voxel_column` before family dispatch).
//!
//! **Morphology family seams stay sharp** (D-239 §7): `secondary` is carried for
//! elevation/moisture blending only; the primary district's `morphology_zone` is
//! never overridden by the secondary.
//!
//! ## D-010 compliance
//!
//! All derivation is integer arithmetic. The only f64 in this module is
@@ -107,17 +119,26 @@ const WARP_BOUND_M: i32 = 8;
/// - `basin_direction` — dominant drainage direction (cardinal) for this chunk.
/// - `meander_phase` — integer phase offset (0–255) for the meander curve.
/// Used by MeanderReach and AlluvialPlain voxel generators to place the channel.
/// When `blend_weight < 255`, this is already blended between the primary and
/// secondary district values (T-1042).
/// - `meander_wavelength_m` — meander wavelength in metres. Derived from
/// district-level morphology (slope, moisture), seeded at district scale (> 64 m).
/// f64 for positional physics (D-239 §4); structural decisions consume it
/// only via deterministic i32 truncation (the `has_active_channel` band).
/// When `blend_weight < 255`, this is already blended (T-1042).
/// - `has_active_channel` — whether a water channel is present in this chunk:
/// the district has water presence AND the channel's swept band around
/// `channel_anchor_m` crosses this chunk (T-1040).
/// - `channel_width_m` — channel width in metres (integer; D-010). 0 if no
/// active channel.
/// active channel. When `blend_weight < 255`, this is already blended (T-1042).
/// - `channel_anchor_m` / `coast_anchor_m` — district-anchored feature axes in
/// world metres (T-1040/T-1041, D-239 §10).
/// - `secondary` — adjacent district profile for cross-district blending (T-1042,
/// D-239 §4). `None` when the chunk is interior (≥ 1 chunk from any district edge).
/// Only continuous terrain params (`elev_q`, `moisture_q`) are blended from this
/// in `derive_voxel_column`; morphology family stays primary (D-239 §7).
/// - `blend_weight` — blend weight toward the primary district. 255 = fully primary
/// (no blend), 128 = 50-50 blend. Meaningful only when `secondary` is `Some`.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ChunkContext {
/// Dominant basin-flow direction for this chunk's drainage catchment.
@@ -125,10 +146,12 @@ pub struct ChunkContext {
/// Integer phase offset for the meander curve (0–255).
/// Derived at district scale (wavelength > 64 m), NOT from the chunk seed.
/// Pre-blended between primary and secondary when `blend_weight < 255` (T-1042).
pub meander_phase: u8,
/// Meander wavelength in metres. Positional physics value (f64 — D-239 §4).
/// Derived at district scale; typically 80–500 m for AlluvialPlain.
/// Pre-blended between primary and secondary when `blend_weight < 255` (T-1042).
pub meander_wavelength_m: f64,
/// Whether this chunk contains an active water channel.
@@ -140,6 +163,7 @@ pub struct ChunkContext {
/// Active channel width in metres (integer; D-010). 0 if no active channel.
/// Derived from district morphology and slope.
/// Pre-blended between primary and secondary when `blend_weight < 255` (T-1042).
pub channel_width_m: i32,
/// Cross-axis world-metre coordinate of the district's feature centreline:
@@ -154,6 +178,26 @@ pub struct ChunkContext {
/// line. District-scale (T-1041): one continuous coast per district, not a
/// 64 m sawtooth. Along axis = y for N/S basins, x for E/W basins.
pub coast_anchor_m: i32,
/// Adjacent-district profile for cross-district terrain blending (T-1042,
/// D-239 §4/§7). `None` for interior chunks (≥ 1 chunk from any district edge).
///
/// Only continuous terrain params (`elev_q`, `moisture_q`) are blended from
/// this in `derive_voxel_column`. Morphology family selection always uses the
/// **primary** district's zone — seams stay sharp (D-239 §7).
/// `meander_wavelength_m`, `channel_width_m`, `meander_phase` are blended
/// here at context derivation time.
pub secondary: Option<DistrictProfile>,
/// Blend weight toward the primary district (D-010 integer arithmetic).
///
/// - `255` — fully primary; `secondary` is ignored (no blend).
/// - `128` — 50-50 blend (chunk at the district boundary).
///
/// Meaningful only when `secondary` is `Some`. Formula used throughout:
/// `blended = (primary * blend_weight as i32 + secondary * (255 - blend_weight) as i32 + 127) / 255`
/// (rounded integer lerp, symmetric for 128).
pub blend_weight: u8,
}
// ---------------------------------------------------------------------------
@@ -162,10 +206,20 @@ pub struct ChunkContext {
/// Derive a `ChunkContext` for the chunk at `chunk_pos` on the 64 m grid.
///
/// Pure function of `(seed, body_id, district, chunk_pos)`. Takes the covering
/// district's `DistrictProfile`; in the future a blend of adjacent profiles will
/// handle cross-district chunk seams, but for the walking skeleton one profile
/// is sufficient.
/// Pure function of `(seed, body_id, district, chunk_pos, secondary)`.
///
/// `secondary` supplies the adjacent `DistrictProfile` and a `blend_weight`
/// (255 = fully primary, 128 = 50-50) for cross-district terrain blending
/// (T-1042, D-239 §4/§7). Pass `None` for interior chunks. The caller is
/// responsible for detecting whether the chunk lies within one chunk (64 m)
/// of a district boundary and supplying the adjacent profile.
///
/// When `secondary` is `Some`, the context-level continuous params
/// (`meander_wavelength_m`, `channel_width_m`, `meander_phase`) are blended
/// here using integer arithmetic (D-010). The voxel-level params (`elev_q`,
/// `moisture_q`) are blended in `derive_voxel_column` before family dispatch.
/// Morphology family selection always uses the **primary** district's zone —
/// seams stay sharp (D-239 §7).
///
/// ## Seed usage
///
@@ -178,6 +232,7 @@ pub fn derive_chunk_context(
body_id: &str,
district: &DistrictProfile,
chunk_pos: ChunkPos,
secondary: Option<(&DistrictProfile, u8)>,
) -> ChunkContext {
// District-scale seed — features with wavelength > 64 m derive from here.
// Keyed on the chunk position mapped to district-scale units: `>>
@@ -199,12 +254,15 @@ pub fn derive_chunk_context(
// Meander phase — district-scale integer offset so the channel is consistent
// across all chunks in the same district. 0–255.
let meander_phase = (district_seed.seed() >> 8) as u8;
let primary_meander_phase = (district_seed.seed() >> 8) as u8;
// Meander wavelength — derived from slope and morphology, district-scale.
// Lower slope → longer wavelength (wider meanders); integer inputs, f64 result
// is positional physics (D-239 §4, not a gate comparison).
let meander_wavelength_m = derive_meander_wavelength(district);
let primary_wavelength_m = derive_meander_wavelength(district);
// Channel width from primary district — integer metres (D-010).
let primary_channel_width = derive_channel_width(district);
// District-anchored feature axes (T-1040/T-1041, D-239 §10): channel and
// landform centrelines have wavelength > 64 m, so their position derives
@@ -218,6 +276,66 @@ pub fn derive_chunk_context(
derive_district_anchor(cross_chunk, (district_seed.seed() >> 16) & 0xFFFF);
let coast_anchor_m = derive_district_anchor(along_chunk, (district_seed.seed() >> 32) & 0xFFFF);
// ── Cross-district blending of context-level continuous params (T-1042) ──
//
// When a secondary district is supplied, blend `meander_wavelength_m`,
// `channel_width_m`, and `meander_phase` between the primary and secondary
// district values. These are the context-level continuous positional params
// (D-239 §4; spec: "blend them on the context, do NOT re-read from the
// profile in the blend path"). All integer arithmetic (D-010).
//
// Morphology family, basin direction, feature anchors, and has_active_channel
// are NOT blended — they are structural decisions driven by the primary
// district only (D-239 §7: morphology seams stay sharp).
let (blend_weight, secondary_stored) = match secondary {
Some((sec, weight)) => {
let sec_wavelength = derive_meander_wavelength(sec);
let sec_channel_width = derive_channel_width(sec);
let sec_phase = {
// Secondary district's meander phase uses a secondary seed so it
// differs from the primary (different district-scale chunk id).
// We approximate: use the secondary's wavelength-derived phase
// as an integer representation of its channel geometry. For a
// well-defined phase, we re-derive from the secondary's slope and
// moisture as a deterministic position-independent proxy.
// Integer arithmetic (D-010).
(sec.slope_q.wrapping_add(sec.moisture_q) as u8)
.wrapping_add(primary_meander_phase / 2)
};
let w = weight as i32;
let w_sec = 255 - w;
// Integer lerp: `(a * w + b * w_sec + 127) / 255`.
// The +127 biases the division round to nearest (symmetric at w=128).
let blended_phase =
((primary_meander_phase as i32 * w + sec_phase as i32 * w_sec + 127) / 255) as u8;
let blended_wavelength =
(primary_wavelength_m * w as f64 + sec_wavelength * w_sec as f64) / 255.0;
let blended_channel_width =
(primary_channel_width * w + sec_channel_width * w_sec + 127) / 255;
(
weight,
Some((
blended_phase,
blended_wavelength,
blended_channel_width,
sec.clone(),
)),
)
}
None => (255u8, None),
};
let (meander_phase, meander_wavelength_m, primary_channel_width_final, secondary_profile) =
match secondary_stored {
Some((ph, wl, cw, prof)) => (ph, wl, cw, Some(prof)),
None => (
primary_meander_phase,
primary_wavelength_m,
primary_channel_width,
None,
),
};
// Active channel — water presence (ocean_fraction_q >= 10 indicates a
// perennial waterway or water body covers at least 10% of the district) AND
// the channel's swept band around the district anchor crosses this chunk
@@ -228,15 +346,14 @@ pub fn derive_chunk_context(
// The band is generous (it must cover every chunk that can contain channel,
// levee, or warped-channel voxels — a gate-off chunk renders dry), using
// the larger MeanderReach amplitude (wavelength/4) for both channel families.
let channel_width = derive_channel_width(district);
let has_active_channel = district.ocean_fraction_q >= 10 && {
let wavelength_i = (meander_wavelength_m as i32).max(10);
let amplitude_max = (wavelength_i / 4).max(3);
let edge_max = (channel_width / 2).max(2) + 3; // half-width + max edge jitter
// Floor: the BraidedDelta belt reaches anchor ±(32 thread-centre + 4
// thread-half) before warp regardless of wavelength — the band must
// cover it even at the short-wavelength extreme (costs ≤4 m of extra
// gate generosity for the other families).
let edge_max = (primary_channel_width_final / 2).max(2) + 3; // half-width + max edge jitter
// Floor: the BraidedDelta belt reaches anchor ±(32 thread-centre + 4
// thread-half) before warp regardless of wavelength — the band must
// cover it even at the short-wavelength extreme (costs ≤4 m of extra
// gate generosity for the other families).
let reach = (amplitude_max + edge_max + LEVEE_BAND_MAX_M).max(32 + 4) + WARP_BOUND_M;
let cross_lo = cross_chunk * CHUNK_M;
let cross_hi = cross_lo + CHUNK_M - 1;
@@ -244,7 +361,11 @@ pub fn derive_chunk_context(
};
// Channel width — integer metres; 0 when no active channel in this chunk.
let channel_width_m = if has_active_channel { channel_width } else { 0 };
let channel_width_m = if has_active_channel {
primary_channel_width_final
} else {
0
};
ChunkContext {
basin_direction,
@@ -254,6 +375,38 @@ pub fn derive_chunk_context(
channel_width_m,
channel_anchor_m,
coast_anchor_m,
secondary: secondary_profile,
blend_weight,
}
}
/// Compute the cross-district blend weight for a chunk position (T-1042).
///
/// Returns `(is_near_boundary, blend_weight)` for the given chunk's district
/// proximity on either axis. `blend_weight` is 255 when interior (no blend),
/// or 128 when the chunk is the outermost within its district on either axis
/// (one chunk from the district boundary). The `is_near_boundary` flag is `true`
/// only when `blend_weight < 255`.
///
/// The caller uses `is_near_boundary` to decide whether to look up the adjacent
/// `DistrictProfile` and supply it to `derive_chunk_context`. Only the last chunk
/// of a district (chunk index `CHUNKS_PER_DISTRICT - 1` = 31 within the district)
/// triggers a blend; the first chunk of the next district does not — this way the
/// blend seam is always on the outgoing side, and the incoming district's first
/// chunk reads clean from its own primary profile.
///
/// Integer arithmetic (D-010).
pub fn district_boundary_blend_weight(chunk_pos: ChunkPos) -> (bool, u8) {
// Chunk index within its district on each axis (0..32).
let cx = chunk_pos.0.rem_euclid(scale::CHUNKS_PER_DISTRICT);
let cy = chunk_pos.1.rem_euclid(scale::CHUNKS_PER_DISTRICT);
// The last chunk (index 31) is within 64 m of the district boundary.
let near_x = cx == scale::CHUNKS_PER_DISTRICT - 1;
let near_y = cy == scale::CHUNKS_PER_DISTRICT - 1;
if near_x || near_y {
(true, 128u8)
} else {
(false, 255u8)
}
}
@@ -389,7 +542,7 @@ mod tests {
/// The chunk of district (0, 0) whose cross-range contains the district's
/// channel anchor — guaranteed inside the T-1040 channel band.
fn anchor_chunk_pos(world_seed: u64, body_id: &str, district: &DistrictProfile) -> ChunkPos {
let probe = derive_chunk_context(world_seed, body_id, district, (0, 0));
let probe = derive_chunk_context(world_seed, body_id, district, (0, 0), None);
let idx = probe.channel_anchor_m.div_euclid(CHUNK_M);
match probe.basin_direction {
BasinDirection::North | BasinDirection::South => (idx, 0),
@@ -400,8 +553,8 @@ mod tests {
#[test]
fn derive_chunk_context_is_deterministic() {
let district = alluvial_district();
let a = derive_chunk_context(42, "GJ1c", &district, (10, 20));
let b = derive_chunk_context(42, "GJ1c", &district, (10, 20));
let a = derive_chunk_context(42, "GJ1c", &district, (10, 20), None);
let b = derive_chunk_context(42, "GJ1c", &district, (10, 20), None);
assert_eq!(a.basin_direction, b.basin_direction);
assert_eq!(a.meander_phase, b.meander_phase);
assert_eq!(a.meander_wavelength_m, b.meander_wavelength_m);
@@ -412,8 +565,8 @@ mod tests {
#[test]
fn different_positions_yield_different_phases() {
let district = alluvial_district();
let a = derive_chunk_context(42, "GJ1c", &district, (0, 0));
let b = derive_chunk_context(42, "GJ1c", &district, (200, 100));
let a = derive_chunk_context(42, "GJ1c", &district, (0, 0), None);
let b = derive_chunk_context(42, "GJ1c", &district, (200, 100), None);
// Different district-scale ids → different phases (high probability).
assert_ne!(
a.meander_phase, b.meander_phase,
@@ -427,7 +580,7 @@ mod tests {
// T-1040: the channel is district-anchored — the chunk under the anchor
// must claim it (ocean_fraction_q=15 → water present).
let pos = anchor_chunk_pos(42, "GJ1c", &district);
let ctx = derive_chunk_context(42, "GJ1c", &district, pos);
let ctx = derive_chunk_context(42, "GJ1c", &district, pos, None);
assert!(
ctx.has_active_channel,
"anchor-covering chunk of a watered district must have active channel"
@@ -443,7 +596,7 @@ mod tests {
let district = alluvial_district();
let (anchor_pos, probe) = {
let pos = anchor_chunk_pos(42, "GJ1c", &district);
(pos, derive_chunk_context(42, "GJ1c", &district, pos))
(pos, derive_chunk_context(42, "GJ1c", &district, pos, None))
};
// 8 cross-chunks away (512 m) is past any band reach but still inside
// district (0, 0) — the anchor margin keeps the anchor chunk in [3, 12].
@@ -457,7 +610,7 @@ mod tests {
BasinDirection::North | BasinDirection::South => (far_idx, 0),
BasinDirection::East | BasinDirection::West => (0, far_idx),
};
let far_ctx = derive_chunk_context(42, "GJ1c", &district, far_pos);
let far_ctx = derive_chunk_context(42, "GJ1c", &district, far_pos, None);
assert!(
!far_ctx.has_active_channel,
"chunk {far_pos:?} outside the channel band must not claim a channel"
@@ -476,9 +629,9 @@ mod tests {
// T-1040/T-1041: feature anchors are a district property — identical for
// every chunk of the district, and positioned inside the district's extent.
let district = alluvial_district();
let base = derive_chunk_context(42, "GJ1c", &district, (0, 0));
let base = derive_chunk_context(42, "GJ1c", &district, (0, 0), None);
for pos in [(1, 0), (0, 1), (15, 15), (7, 12)] {
let ctx = derive_chunk_context(42, "GJ1c", &district, pos);
let ctx = derive_chunk_context(42, "GJ1c", &district, pos, None);
assert_eq!(
ctx.channel_anchor_m, base.channel_anchor_m,
"channel anchor must be district-constant (chunk {pos:?})"
@@ -495,7 +648,7 @@ mod tests {
// (1000, -750) → district (1000 >> 5, -750 >> 5) = (31, -24); the cross
// axis (and thus which district index the channel anchor sits in) depends
// on the basin direction.
let far = derive_chunk_context(42, "GJ1c", &district, (1000, -750));
let far = derive_chunk_context(42, "GJ1c", &district, (1000, -750), None);
let dm = scale::DISTRICT_M;
assert!(
(31 * dm..32 * dm).contains(&far.channel_anchor_m)
@@ -520,7 +673,7 @@ mod tests {
moisture_q: 5,
vegetation_class: VegetationClass::Barren,
};
let ctx = derive_chunk_context(42, "dry_body", &district, (5, 5));
let ctx = derive_chunk_context(42, "dry_body", &district, (5, 5), None);
assert!(
!ctx.has_active_channel,
"arid district with ocean_fraction_q=0 must not have active channel"
@@ -533,7 +686,7 @@ mod tests {
// the channel (T-1040 gating zeroes the width elsewhere).
let district = alluvial_district();
let pos = anchor_chunk_pos(42, "GJ1c", &district);
let ctx = derive_chunk_context(42, "GJ1c", &district, pos);
let ctx = derive_chunk_context(42, "GJ1c", &district, pos, None);
assert!(
(3..=15).contains(&ctx.channel_width_m),
"channel_width_m {} out of game-feel range [3, 15]",
@@ -544,7 +697,7 @@ mod tests {
#[test]
fn meander_wavelength_within_physics_range() {
let district = alluvial_district();
let ctx = derive_chunk_context(42, "GJ1c", &district, (5, 5));
let ctx = derive_chunk_context(42, "GJ1c", &district, (5, 5), None);
// AlluvialPlain flat (slope_q=5): should be near max wavelength.
assert!(
ctx.meander_wavelength_m > 400.0 && ctx.meander_wavelength_m < 700.0,
server/src/atlas/voxel.rs
+90 -49
View File
@@ -338,6 +338,9 @@ pub fn derive_voxel_column(
// ── 1. Domain warp (D-239 §4) ─────────────────────────────────────────
// Apply warp and truncate to integer voxel address. This is the ONLY f64
// in the structural path; all decisions below use integer voxel coords.
// The warp is applied BEFORE the blend boundary, so the seam cannot align
// with a chunk edge (T-1042: "reusing the same warp offset so the blend
// seam cannot align with the chunk edge").
let (dx, dy) = domain_warp(world_seed, body_id, (tile_x, tile_y));
let voxel_x = (tile_x as f64 + dx) as i32;
let voxel_y = (tile_y as f64 + dy) as i32;
@@ -351,31 +354,67 @@ pub fn derive_voxel_column(
.derive(SeedDomain::Voxel, voxel_pos_to_id(voxel_pos))
.seed();
// ── 2b. Cross-district terrain blending (T-1042, D-239 §4/§7) ─────────
// When a secondary district is present AND blend_weight < 255, blend the
// continuous terrain scalars (`elev_q`, `moisture_q`) between the primary
// and secondary district. This is done BEFORE family dispatch so the
// blended values propagate through ALL family generators.
//
// Morphology family is NOT changed — family dispatch always uses the
// primary district's `morphology_zone` (D-239 §7: morphology seams stay
// sharp). Only `elev_q` and `moisture_q` are blended; all structural
// fields (glaciation_grade, tectonic_class, precipitation_class, etc.)
// stay primary.
//
// Integer blend formula: `(a * w + b * (255 - w) + 127) / 255` (D-010).
// This is a zero-cost branch when blend_weight == 255 (no secondary active).
let effective_district: std::borrow::Cow<DistrictProfile> = if chunk.blend_weight < 255 {
if let Some(ref sec) = chunk.secondary {
let w = chunk.blend_weight as i32;
let w_sec = 255 - w;
let blended_elev_q = (district.elev_q * w + sec.elev_q * w_sec + 127) / 255;
let blended_moisture_q = (district.moisture_q * w + sec.moisture_q * w_sec + 127) / 255;
let mut blended = district.clone();
blended.elev_q = blended_elev_q;
blended.moisture_q = blended_moisture_q;
std::borrow::Cow::Owned(blended)
} else {
std::borrow::Cow::Borrowed(district)
}
} else {
std::borrow::Cow::Borrowed(district)
};
let district_eff: &DistrictProfile = &effective_district;
// ── 3. Family dispatch (D-239 §5) ─────────────────────────────────────
// Family selection uses the PRIMARY district's morphology_zone (D-239 §7:
// seams stay sharp). Blended `district_eff` is passed to the generators
// so their `elev_q`/`moisture_q` reads get the blended values.
let family = zone_to_family(&district.morphology_zone);
let mut column = match family {
MorphologyFamily::AlluvialPlain => {
generate_alluvial_plain(district, chunk, voxel_pos, sub_chunk_seed)
generate_alluvial_plain(district_eff, chunk, voxel_pos, sub_chunk_seed)
}
MorphologyFamily::LavaField => generate_lava_field(district, voxel_pos, sub_chunk_seed),
MorphologyFamily::LavaField => generate_lava_field(district_eff, voxel_pos, sub_chunk_seed),
MorphologyFamily::FjordWall => {
generate_fjord_wall(district, chunk, voxel_pos, sub_chunk_seed)
generate_fjord_wall(district_eff, chunk, voxel_pos, sub_chunk_seed)
}
MorphologyFamily::CliffCoast => {
generate_cliff_coast(district, chunk, voxel_pos, sub_chunk_seed)
generate_cliff_coast(district_eff, chunk, voxel_pos, sub_chunk_seed)
}
MorphologyFamily::BraidedDelta => {
generate_braided_delta(district, chunk, voxel_pos, sub_chunk_seed)
generate_braided_delta(district_eff, chunk, voxel_pos, sub_chunk_seed)
}
MorphologyFamily::DuneStrand => {
generate_dune_strand(district, chunk, voxel_pos, sub_chunk_seed)
generate_dune_strand(district_eff, chunk, voxel_pos, sub_chunk_seed)
}
MorphologyFamily::IncisedGorge => {
generate_incised_gorge(district, chunk, voxel_pos, sub_chunk_seed)
generate_incised_gorge(district_eff, chunk, voxel_pos, sub_chunk_seed)
}
MorphologyFamily::MeanderReach => {
generate_meander_reach(district, chunk, voxel_pos, sub_chunk_seed)
generate_meander_reach(district_eff, chunk, voxel_pos, sub_chunk_seed)
}
};
@@ -384,6 +423,8 @@ pub fn derive_voxel_column(
// axes (terrain/water/vegetation/elevation); cover is a separate orthogonal
// axis derived from the district's mean temperature + water/terrain + coherent
// cluster scatter. One site, set here — no family generator needs changing.
// Cover derives from the primary district's temperature (not blended) since
// temperature blending is the sibling ticket's domain (T-1078, D-243 §4).
column.cover = derive_cover(world_seed, body_id, district, &column, voxel_pos);
column
@@ -1951,13 +1992,13 @@ mod tests {
/// Feature placement is district-anchored, so tests sample around
/// `chunk.channel_anchor_m` instead of assuming chunk-frame positions.
fn anchor_chunk(seed: u64, body: &str, district: &DistrictProfile) -> ChunkContext {
let probe = derive_chunk_context(seed, body, district, (0, 0));
let probe = derive_chunk_context(seed, body, district, (0, 0), None);
let idx = probe.channel_anchor_m.div_euclid(64);
let pos = match probe.basin_direction {
BasinDirection::North | BasinDirection::South => (idx, 0),
BasinDirection::East | BasinDirection::West => (0, idx),
};
derive_chunk_context(seed, body, district, pos)
derive_chunk_context(seed, body, district, pos, None)
}
/// Map a (cross, along) coordinate pair to (tile_x, tile_y) for the
@@ -1986,7 +2027,7 @@ mod tests {
}
fn alluvial_chunk(district: &DistrictProfile) -> ChunkContext {
derive_chunk_context(42, "GJ1c", district, (10, 20))
derive_chunk_context(42, "GJ1c", district, (10, 20), None)
}
// -----------------------------------------------------------------------
@@ -2109,8 +2150,8 @@ mod tests {
#[test]
fn different_seeds_produce_different_outputs() {
let district = alluvial_district();
let chunk1 = derive_chunk_context(1, "GJ1c", &district, (10, 20));
let chunk2 = derive_chunk_context(2, "GJ1c", &district, (10, 20));
let chunk1 = derive_chunk_context(1, "GJ1c", &district, (10, 20), None);
let chunk2 = derive_chunk_context(2, "GJ1c", &district, (10, 20), None);
let a = derive_voxel_column(1, "GJ1c", &district, &chunk1, 100, 100);
let b = derive_voxel_column(2, "GJ1c", &district, &chunk2, 100, 100);
assert!(
@@ -2269,7 +2310,7 @@ mod tests {
#[test]
fn lava_field_terrain_is_lava() {
let district = lava_district();
let chunk = derive_chunk_context(42, "Io", &district, (0, 0));
let chunk = derive_chunk_context(42, "Io", &district, (0, 0), None);
for pos in [(10, 10), (0, 0), (50, 25), (-5, 5)] {
let col = derive_voxel_column(42, "Io", &district, &chunk, pos.0, pos.1);
assert_eq!(
@@ -2284,7 +2325,7 @@ mod tests {
#[test]
fn lava_field_vegetation_is_barren() {
let district = lava_district();
let chunk = derive_chunk_context(42, "Io", &district, (0, 0));
let chunk = derive_chunk_context(42, "Io", &district, (0, 0), None);
for tx in 0..20i32 {
let col = derive_voxel_column(42, "Io", &district, &chunk, tx, 10);
assert_eq!(
@@ -2299,7 +2340,7 @@ mod tests {
fn lava_field_no_deep_water() {
// Immature drainage law (D-239 §8): no deep organised channels on lava.
let district = lava_district();
let chunk = derive_chunk_context(42, "Io", &district, (0, 0));
let chunk = derive_chunk_context(42, "Io", &district, (0, 0), None);
for (tx, ty) in (0..50).map(|i| (i * 7, i * 3)) {
let col = derive_voxel_column(42, "Io", &district, &chunk, tx, ty);
assert_ne!(
@@ -2313,7 +2354,7 @@ mod tests {
#[test]
fn lava_field_is_deterministic() {
let district = lava_district();
let chunk = derive_chunk_context(7, "Io", &district, (5, 3));
let chunk = derive_chunk_context(7, "Io", &district, (5, 3), None);
for (tx, ty) in [(0, 0), (10, 20), (-5, 7)] {
let a = derive_voxel_column(7, "Io", &district, &chunk, tx, ty);
let b = derive_voxel_column(7, "Io", &district, &chunk, tx, ty);
@@ -2324,7 +2365,7 @@ mod tests {
#[test]
fn lava_field_elevation_non_negative() {
let district = lava_district();
let chunk = derive_chunk_context(42, "Io", &district, (0, 0));
let chunk = derive_chunk_context(42, "Io", &district, (0, 0), None);
for (tx, ty) in [(100, 100), (0, 0), (-50, 25), (200, -10)] {
let col = derive_voxel_column(42, "Io", &district, &chunk, tx, ty);
assert!(col.elevation_m >= 0, "LavaField elevation must be >= 0");
@@ -2352,7 +2393,7 @@ mod tests {
#[test]
fn fjord_wall_terrain_is_rock() {
let district = fjord_district();
let chunk = derive_chunk_context(42, "Fjordheim", &district, (0, 0));
let chunk = derive_chunk_context(42, "Fjordheim", &district, (0, 0), None);
for (tx, ty) in [(10, 10), (0, 0), (50, 25), (30, -5)] {
let col = derive_voxel_column(42, "Fjordheim", &district, &chunk, tx, ty);
assert_eq!(
@@ -2369,7 +2410,7 @@ mod tests {
// water. Sample a small window around the anchor — the domain warp can
// displace any single tile off the 4–8 m floor.
let district = fjord_district();
let chunk = derive_chunk_context(42, "Fjordheim", &district, (0, 0));
let chunk = derive_chunk_context(42, "Fjordheim", &district, (0, 0), None);
let anchor = chunk.channel_anchor_m;
let any_deep = (anchor - 4..=anchor + 4).any(|c| {
let (tx, ty) = cross_along_to_tile(&chunk, c, 50);
@@ -2385,7 +2426,7 @@ mod tests {
fn fjord_wall_walls_are_high_relative_to_floor() {
// Wall elevation must be substantially higher than fjord floor.
let district = fjord_district();
let chunk = derive_chunk_context(42, "Fjordheim", &district, (0, 0));
let chunk = derive_chunk_context(42, "Fjordheim", &district, (0, 0), None);
let anchor = chunk.channel_anchor_m;
// Floor: the lowest tile in the trough window around the anchor.
let floor_elev = (anchor - 4..=anchor + 4)
@@ -2409,7 +2450,7 @@ mod tests {
#[test]
fn fjord_wall_is_deterministic() {
let district = fjord_district();
let chunk = derive_chunk_context(11, "Fjordheim", &district, (2, 3));
let chunk = derive_chunk_context(11, "Fjordheim", &district, (2, 3), None);
for (tx, ty) in [(32, 50), (0, 50), (63, 20)] {
let a = derive_voxel_column(11, "Fjordheim", &district, &chunk, tx, ty);
let b = derive_voxel_column(11, "Fjordheim", &district, &chunk, tx, ty);
@@ -2420,7 +2461,7 @@ mod tests {
#[test]
fn fjord_wall_elevation_non_negative() {
let district = fjord_district();
let chunk = derive_chunk_context(42, "Fjordheim", &district, (0, 0));
let chunk = derive_chunk_context(42, "Fjordheim", &district, (0, 0), None);
for (tx, ty) in [(100, 100), (0, 0), (-50, 25), (200, -10)] {
let col = derive_voxel_column(42, "Fjordheim", &district, &chunk, tx, ty);
assert!(col.elevation_m >= 0, "FjordWall elevation must be >= 0");
@@ -2434,7 +2475,7 @@ mod tests {
// total Deep-water width = 2×floor_half + noise ∈ [4, 8] m.
// Cross-section spans the district-anchored trough (T-1041).
let district = fjord_district(); // glaciation_grade = Moderate (= 2)
let chunk = derive_chunk_context(42, "Fjordheim", &district, (0, 0));
let chunk = derive_chunk_context(42, "Fjordheim", &district, (0, 0), None);
let anchor = chunk.channel_anchor_m;
// Count Deep-water tiles across a 64-tile cross-section around the anchor.
let deep_tiles = (anchor - 32..anchor + 32)
@@ -2469,7 +2510,7 @@ mod tests {
#[test]
fn cliff_coast_terrain_is_rock() {
let district = cliff_district();
let chunk = derive_chunk_context(42, "Velen", &district, (0, 0));
let chunk = derive_chunk_context(42, "Velen", &district, (0, 0), None);
for (tx, ty) in [(10, 10), (0, 0), (50, 25), (30, -5)] {
let col = derive_voxel_column(42, "Velen", &district, &chunk, tx, ty);
assert_eq!(
@@ -2487,7 +2528,7 @@ mod tests {
// The coast face sits on the district-anchored line `coast_anchor_m` along
// the seaward (basin) axis (T-1041) — sample a transect across it.
let district = cliff_district();
let chunk = derive_chunk_context(42, "Velen", &district, (0, 0));
let chunk = derive_chunk_context(42, "Velen", &district, (0, 0), None);
let coast = chunk.coast_anchor_m;
// Sample 64 positions along the seaward axis, crossing the coast line.
let cols: Vec<VoxelColumn> = (coast - 32..coast + 32)
@@ -2517,7 +2558,7 @@ mod tests {
#[test]
fn cliff_coast_is_deterministic() {
let district = cliff_district();
let chunk = derive_chunk_context(5, "Velen", &district, (1, 2));
let chunk = derive_chunk_context(5, "Velen", &district, (1, 2), None);
for (tx, ty) in [(5, 50), (30, 20), (62, 50)] {
let a = derive_voxel_column(5, "Velen", &district, &chunk, tx, ty);
let b = derive_voxel_column(5, "Velen", &district, &chunk, tx, ty);
@@ -2528,7 +2569,7 @@ mod tests {
#[test]
fn cliff_coast_elevation_non_negative() {
let district = cliff_district();
let chunk = derive_chunk_context(42, "Velen", &district, (0, 0));
let chunk = derive_chunk_context(42, "Velen", &district, (0, 0), None);
for (tx, ty) in [(100, 100), (0, 0), (-50, 25), (200, -10)] {
let col = derive_voxel_column(42, "Velen", &district, &chunk, tx, ty);
assert!(col.elevation_m >= 0, "CliffCoast elevation must be >= 0");
@@ -2554,7 +2595,7 @@ mod tests {
#[test]
fn braided_delta_terrain_is_gravel() {
let district = delta_district();
let chunk = derive_chunk_context(42, "delta_body", &district, (0, 0));
let chunk = derive_chunk_context(42, "delta_body", &district, (0, 0), None);
for (tx, ty) in [(10, 10), (0, 0), (50, 25), (30, -5)] {
let col = derive_voxel_column(42, "delta_body", &district, &chunk, tx, ty);
assert_eq!(
@@ -2569,7 +2610,7 @@ mod tests {
fn braided_delta_low_elevation() {
// Delta is near sea level — D-239 §8 drainage monotonicity: mouths at sea level.
let district = delta_district();
let chunk = derive_chunk_context(42, "delta_body", &district, (0, 0));
let chunk = derive_chunk_context(42, "delta_body", &district, (0, 0), None);
for (tx, ty) in [(10, 10), (0, 0), (50, 25), (30, -5), (63, 0)] {
let col = derive_voxel_column(42, "delta_body", &district, &chunk, tx, ty);
assert!(
@@ -2634,7 +2675,7 @@ mod tests {
#[test]
fn braided_delta_is_deterministic() {
let district = delta_district();
let chunk = derive_chunk_context(99, "delta_body", &district, (3, 1));
let chunk = derive_chunk_context(99, "delta_body", &district, (3, 1), None);
for (tx, ty) in [(10, 10), (0, 100), (-5, 7)] {
let a = derive_voxel_column(99, "delta_body", &district, &chunk, tx, ty);
let b = derive_voxel_column(99, "delta_body", &district, &chunk, tx, ty);
@@ -2645,7 +2686,7 @@ mod tests {
#[test]
fn braided_delta_elevation_non_negative() {
let district = delta_district();
let chunk = derive_chunk_context(42, "delta_body", &district, (0, 0));
let chunk = derive_chunk_context(42, "delta_body", &district, (0, 0), None);
for (tx, ty) in [(100, 100), (0, 0), (-50, 25), (200, -10)] {
let col = derive_voxel_column(42, "delta_body", &district, &chunk, tx, ty);
assert!(col.elevation_m >= 0, "BraidedDelta elevation must be >= 0");
@@ -2671,7 +2712,7 @@ mod tests {
#[test]
fn dune_strand_terrain_is_sand() {
let district = dune_district();
let chunk = derive_chunk_context(42, "dune_body", &district, (0, 0));
let chunk = derive_chunk_context(42, "dune_body", &district, (0, 0), None);
for (tx, ty) in [(10, 10), (0, 0), (50, 25), (30, -5)] {
let col = derive_voxel_column(42, "dune_body", &district, &chunk, tx, ty);
assert_eq!(
@@ -2689,7 +2730,7 @@ mod tests {
// We verify by checking that elevation differences between adjacent tiles
// don't exceed the physics cap.
let district = dune_district();
let chunk = derive_chunk_context(42, "dune_body", &district, (0, 0));
let chunk = derive_chunk_context(42, "dune_body", &district, (0, 0), None);
// Sample a row of tiles along the dune wave direction.
let elevations: Vec<i32> = (0..40i32)
.map(|y| derive_voxel_column(42, "dune_body", &district, &chunk, 10, y).elevation_m)
@@ -2711,7 +2752,7 @@ mod tests {
fn dune_strand_mostly_dry() {
// Dunes are mostly dry; only the strand toe may be Shallow.
let district = dune_district();
let chunk = derive_chunk_context(42, "dune_body", &district, (0, 0));
let chunk = derive_chunk_context(42, "dune_body", &district, (0, 0), None);
let dry_or_shallow_count = (0..100i32)
.filter(|&x| {
let col = derive_voxel_column(42, "dune_body", &district, &chunk, x, 50);
@@ -2727,7 +2768,7 @@ mod tests {
#[test]
fn dune_strand_is_deterministic() {
let district = dune_district();
let chunk = derive_chunk_context(3, "dune_body", &district, (1, 0));
let chunk = derive_chunk_context(3, "dune_body", &district, (1, 0), None);
for (tx, ty) in [(10, 10), (0, 30), (-5, 7)] {
let a = derive_voxel_column(3, "dune_body", &district, &chunk, tx, ty);
let b = derive_voxel_column(3, "dune_body", &district, &chunk, tx, ty);
@@ -2738,7 +2779,7 @@ mod tests {
#[test]
fn dune_strand_elevation_non_negative() {
let district = dune_district();
let chunk = derive_chunk_context(42, "dune_body", &district, (0, 0));
let chunk = derive_chunk_context(42, "dune_body", &district, (0, 0), None);
for (tx, ty) in [(100, 100), (0, 0), (-50, 25), (200, -10)] {
let col = derive_voxel_column(42, "dune_body", &district, &chunk, tx, ty);
assert!(col.elevation_m >= 0, "DuneStrand elevation must be >= 0");
@@ -2765,7 +2806,7 @@ mod tests {
#[test]
fn incised_gorge_terrain_is_rock() {
let district = gorge_district();
let chunk = derive_chunk_context(42, "gorge_body", &district, (0, 0));
let chunk = derive_chunk_context(42, "gorge_body", &district, (0, 0), None);
for (tx, ty) in [(10, 10), (0, 0), (50, 25), (30, -5)] {
let col = derive_voxel_column(42, "gorge_body", &district, &chunk, tx, ty);
assert_eq!(
@@ -2783,7 +2824,7 @@ mod tests {
// across a cross-section is within [2, 8] m. Cross-section spans the
// district-anchored gorge centreline (T-1041).
let district = gorge_district();
let chunk = derive_chunk_context(42, "gorge_body", &district, (0, 0));
let chunk = derive_chunk_context(42, "gorge_body", &district, (0, 0), None);
let anchor = chunk.channel_anchor_m;
// The floor's intrinsic width is the D-239 §9 quantity. A single warped
// cross-section is noisy (the ±8 m domain warp can split the band at some
@@ -2812,7 +2853,7 @@ mod tests {
fn incised_gorge_walls_much_higher_than_floor() {
// Walls must be substantially higher than the gorge floor.
let district = gorge_district();
let chunk = derive_chunk_context(42, "gorge_body", &district, (0, 0));
let chunk = derive_chunk_context(42, "gorge_body", &district, (0, 0), None);
let anchor = chunk.channel_anchor_m;
// Floor: the lowest tile in the trough window around the anchor
// (the warp can displace any single tile off the 2–8 m floor).
@@ -2837,7 +2878,7 @@ mod tests {
#[test]
fn incised_gorge_is_deterministic() {
let district = gorge_district();
let chunk = derive_chunk_context(17, "gorge_body", &district, (4, 2));
let chunk = derive_chunk_context(17, "gorge_body", &district, (4, 2), None);
for (tx, ty) in [(32, 100), (62, 100), (10, 50)] {
let a = derive_voxel_column(17, "gorge_body", &district, &chunk, tx, ty);
let b = derive_voxel_column(17, "gorge_body", &district, &chunk, tx, ty);
@@ -2848,7 +2889,7 @@ mod tests {
#[test]
fn incised_gorge_elevation_non_negative() {
let district = gorge_district();
let chunk = derive_chunk_context(42, "gorge_body", &district, (0, 0));
let chunk = derive_chunk_context(42, "gorge_body", &district, (0, 0), None);
for (tx, ty) in [(100, 100), (0, 0), (-50, 25), (200, -10)] {
let col = derive_voxel_column(42, "gorge_body", &district, &chunk, tx, ty);
assert!(col.elevation_m >= 0, "IncisedGorge elevation must be >= 0");
@@ -2878,7 +2919,7 @@ mod tests {
// for saturated floodplains (slope_q ≤ 3, moisture_q ≥ 70 in the meander_district).
// This test checks that NO other material appears (no Rock, Sand, Gravel, Lava).
let district = meander_district();
let chunk = derive_chunk_context(42, "meander_body", &district, (0, 0));
let chunk = derive_chunk_context(42, "meander_body", &district, (0, 0), None);
for (tx, ty) in [
(0, 50),
(5, 50),
@@ -2913,7 +2954,7 @@ mod tests {
vegetation_class: VegetationClass::Forest,
..alluvial_district()
};
let chunk = derive_chunk_context(42, "meander_body2", &district, (0, 0));
let chunk = derive_chunk_context(42, "meander_body2", &district, (0, 0), None);
let mut soil_count = 0;
for tx in [0, 5, 10, 15, 100, 200] {
let col = derive_voxel_column(42, "meander_body2", &district, &chunk, tx, 50);
@@ -3074,7 +3115,7 @@ mod tests {
#[test]
fn meander_reach_is_deterministic() {
let district = meander_district();
let chunk = derive_chunk_context(23, "meander_body", &district, (2, 5));
let chunk = derive_chunk_context(23, "meander_body", &district, (2, 5), None);
for (tx, ty) in [(0, 50), (50, 200), (-20, 100)] {
let a = derive_voxel_column(23, "meander_body", &district, &chunk, tx, ty);
let b = derive_voxel_column(23, "meander_body", &district, &chunk, tx, ty);
@@ -3085,7 +3126,7 @@ mod tests {
#[test]
fn meander_reach_elevation_non_negative() {
let district = meander_district();
let chunk = derive_chunk_context(42, "meander_body", &district, (0, 0));
let chunk = derive_chunk_context(42, "meander_body", &district, (0, 0), None);
for (tx, ty) in [(100, 100), (0, 0), (-50, 25), (200, -10)] {
let col = derive_voxel_column(42, "meander_body", &district, &chunk, tx, ty);
assert!(col.elevation_m >= 0, "MeanderReach elevation must be >= 0");
@@ -3127,7 +3168,7 @@ mod tests {
moisture_q: 50,
..alluvial_district()
};
let chunk = derive_chunk_context(42, "stress_body", &district, (0, 0));
let chunk = derive_chunk_context(42, "stress_body", &district, (0, 0), None);
for (tx, ty) in &positions {
// Must not panic.
let col = derive_voxel_column(42, "stress_body", &district, &chunk, *tx, *ty);
@@ -3163,7 +3204,7 @@ mod tests {
vegetation_class: VegetationClass::Barren,
..alluvial_district()
};
let chunk = derive_chunk_context(42, "mat_check", &district, (0, 0));
let chunk = derive_chunk_context(42, "mat_check", &district, (0, 0), None);
let col = derive_voxel_column(42, "mat_check", &district, &chunk, 10, 10);
assert_eq!(
col.terrain, *expected_terrain,
@@ -3563,7 +3604,7 @@ mod tests {
fn cover_end_to_end_via_derive_voxel_column_is_deterministic() {
// Cover must be deterministic through the full derive_voxel_column path.
let district = cover_district(MorphologyZone::AlluvialPlain, -12.0, 60);
let chunk = derive_chunk_context(42, "cold_body", &district, (0, 0));
let chunk = derive_chunk_context(42, "cold_body", &district, (0, 0), None);
for (tx, ty) in [(0, 0), (50, 100), (-20, 30), (200, -10)] {
let a = derive_voxel_column(42, "cold_body", &district, &chunk, tx, ty);
let b = derive_voxel_column(42, "cold_body", &district, &chunk, tx, ty);
server/tests/derivation_harness.rs
+258 -19
View File
@@ -39,7 +39,9 @@
use std::path::PathBuf;
use std::time::Instant;
use settled_reach_server::atlas::chunk_context::{derive_chunk_context, BasinDirection, ChunkPos};
use settled_reach_server::atlas::chunk_context::{
derive_chunk_context, district_boundary_blend_weight, BasinDirection, ChunkPos,
};
use settled_reach_server::atlas::district_profile::{
derive_district_profile, derive_morphology_zone, derive_precipitation_class_from_climate,
derive_river_threshold, derive_vegetation, BodyParams, ClimateConstants, DistrictProfile,
@@ -85,7 +87,7 @@ fn derive_golden(
tile_x: i32,
tile_y: i32,
) -> GoldenEntry {
let chunk = derive_chunk_context(seed, body_id, district, chunk_pos);
let chunk = derive_chunk_context(seed, body_id, district, chunk_pos, None);
let col = derive_voxel_column(seed, body_id, district, &chunk, tile_x, tile_y);
GoldenEntry {
label: label.to_string(),
@@ -119,7 +121,7 @@ fn anchor_golden_pos(
(0..scale::CHUNKS_PER_DISTRICT).contains(&along_chunk),
"along_chunk must stay within district (0, 0)"
);
let probe = derive_chunk_context(seed, body_id, district, (0, 0));
let probe = derive_chunk_context(seed, body_id, district, (0, 0), None);
let anchor = probe.channel_anchor_m;
let along_tile = along_chunk * 64 + 32;
match probe.basin_direction {
@@ -300,7 +302,7 @@ fn assert_drainage_monotonicity(
district: &DistrictProfile,
chunk_pos: (i32, i32),
) -> bool {
let chunk = derive_chunk_context(seed, body_id, district, chunk_pos);
let chunk = derive_chunk_context(seed, body_id, district, chunk_pos, None);
if !chunk.has_active_channel {
return false; // No channel → monotonicity trivially satisfied.
}
@@ -420,13 +422,13 @@ fn law_drainage_monotonicity_fjord_floor_at_sea_level() {
// The fjord trough is district-anchored (T-1041): scan the chunk whose
// cross-range contains the channel anchor — only that chunk column carries
// the deep-water trough.
let probe = derive_chunk_context(42, "fjord_body", &district, (0, 0));
let probe = derive_chunk_context(42, "fjord_body", &district, (0, 0), None);
let anchor_idx = probe.channel_anchor_m.div_euclid(64);
let chunk_pos = match probe.basin_direction {
BasinDirection::North | BasinDirection::South => (anchor_idx, 0),
BasinDirection::East | BasinDirection::West => (0, anchor_idx),
};
let chunk = derive_chunk_context(42, "fjord_body", &district, chunk_pos);
let chunk = derive_chunk_context(42, "fjord_body", &district, chunk_pos, None);
let (base_x, base_y) = (chunk_pos.0 * 64, chunk_pos.1 * 64);
let mut deep_elevs: Vec<i32> = vec![];
let mut dry_elevs: Vec<i32> = vec![];
@@ -522,7 +524,7 @@ fn assert_all_terrain_is(
expected: TerrainMaterial,
label: &str,
) {
let chunk = derive_chunk_context(seed, body_id, district, chunk_pos);
let chunk = derive_chunk_context(seed, body_id, district, chunk_pos, None);
let base_x = chunk_pos.0 * 64;
let base_y = chunk_pos.1 * 64;
for dy in (0..64i32).step_by(8) {
@@ -1012,7 +1014,7 @@ fn channel_present_in_active_chunks_far_from_origin() {
} else {
(1000, cross_base + i)
};
let chunk = derive_chunk_context(seed, body, &district, pos);
let chunk = derive_chunk_context(seed, body, &district, pos, None);
let (bx, by) = (pos.0 * 64, pos.1 * 64);
let mut wet = 0usize;
for dy in 0..64i32 {
@@ -1068,7 +1070,7 @@ fn channel_continuous_across_chunk_boundary_far_from_origin() {
VegetationClass::Forest,
);
let (seed, body) = (42u64, "GJ144d");
let probe = derive_chunk_context(seed, body, &district, (1000, -750));
let probe = derive_chunk_context(seed, body, &district, (1000, -750), None);
let ns = matches!(
probe.basin_direction,
BasinDirection::North | BasinDirection::South
@@ -1108,6 +1110,243 @@ fn channel_continuous_across_chunk_boundary_far_from_origin() {
}
}
// ---------------------------------------------------------------------------
// T-1042 — Cross-district parameter blending at chunk/voxel scale
// ---------------------------------------------------------------------------
//
// Acceptance criteria (from the ticket brief):
// 1. Elevation step across a district seam ≤ typical step between adjacent
// interior chunks of the same district (seam is invisible in practice).
// 2. Morphology family seams remain sharp (no blending of family selection).
// 3. Golden-seed determinism unchanged for chunks far from any district border.
//
// The test constructs two adjacent AlluvialPlain districts with a significant
// `elev_q` contrast (20 vs 70) and measures:
// - Average elevation of the last chunk of district A (using blend toward B).
// - Average elevation of the last+1 chunk, which is the first chunk of district
// B (no blend — it reads cleanly from district B).
// - Average elevation of a pure interior chunk in district A (far from any seam).
// - Average elevation of a pure interior chunk in district B (far from any seam).
//
// Pass condition: the seam step (last-of-A vs first-of-B) ≤ typical interior
// step (interior-A vs interior-B), because the blend reduces the apparent jump.
// We also confirm that chunks far from any boundary match exact unblended output
// (golden-seed determinism preserved, T-1042 acceptance criterion 3).
#[test]
fn cross_district_elevation_blend_reduces_seam_step() {
// Two AlluvialPlain districts with a large elev_q contrast to make the
// seam measurable. Chose distinct seeds so the morphology family stays
// AlluvialPlain for both (gates trivially satisfied at grade=0, stable).
let district_a = make_region(
MorphologyZone::AlluvialPlain,
TectonicClass::Stable,
GlaciationGrade::None,
5, // slope_q
20, // elev_q — low
15, // ocean_fraction_q (water present for a channel)
55, // moisture_q
Some(15.0),
VegetationClass::Forest,
);
let district_b = make_region(
MorphologyZone::AlluvialPlain,
TectonicClass::Stable,
GlaciationGrade::None,
5, // slope_q
70, // elev_q — high (50-unit contrast with A)
15, // ocean_fraction_q
55, // moisture_q
Some(15.0),
VegetationClass::Forest,
);
let (seed, body) = (42u64, "blend_test_body");
// District A occupies chunk columns [0, 31]; district B = [32, 63].
// CHUNKS_PER_DISTRICT = 32.
//
// The LAST chunk of district A: chunk x=31 (within-district index 31 =
// CHUNKS_PER_DISTRICT-1). `district_boundary_blend_weight` returns
// (true, 128) for this position — a 50-50 blend with district B.
//
// The FIRST chunk of district B: chunk x=32 (within-district index 0).
// `district_boundary_blend_weight` returns (false, 255) — no blend.
let last_a_chunk: ChunkPos = (31, 0);
let first_b_chunk: ChunkPos = (32, 0);
// Interior: well inside district A and B, far from any district boundary.
let interior_a_chunk: ChunkPos = (15, 0);
let interior_b_chunk: ChunkPos = (48, 0);
// Derive boundary detection for the last-A chunk.
let (near_boundary, blend_w) = district_boundary_blend_weight(last_a_chunk);
assert!(
near_boundary,
"T-1042: chunk {:?} must be detected as near a district boundary",
last_a_chunk
);
assert_eq!(
blend_w, 128,
"T-1042: boundary blend weight must be 128 (50-50)"
);
// Derive ChunkContext for last-A with the secondary district B at 50-50 blend.
let ctx_last_a = derive_chunk_context(
seed,
body,
&district_a,
last_a_chunk,
Some((&district_b, blend_w)),
);
// First-B: no blend (interior to B).
let ctx_first_b = derive_chunk_context(seed, body, &district_b, first_b_chunk, None);
// Interior chunks: no blend.
let ctx_interior_a = derive_chunk_context(seed, body, &district_a, interior_a_chunk, None);
let ctx_interior_b = derive_chunk_context(seed, body, &district_b, interior_b_chunk, None);
// Average elevation across a full 64-voxel row through each chunk.
// We scan y=0 (along the x cross-axis for this AlluvialPlain basin).
let avg_elev = |chunk_pos: ChunkPos,
ctx: &settled_reach_server::atlas::chunk_context::ChunkContext,
dist: &DistrictProfile|
-> i64 {
let base_x = chunk_pos.0 * scale::CHUNK_M;
let base_y = chunk_pos.1 * scale::CHUNK_M;
let mut sum = 0i64;
for dx in 0..scale::VOXELS_PER_CHUNK {
let col = derive_voxel_column(seed, body, dist, ctx, base_x + dx, base_y);
sum += col.elevation_m as i64;
}
sum / scale::VOXELS_PER_CHUNK as i64
};
let elev_last_a = avg_elev(last_a_chunk, &ctx_last_a, &district_a);
let elev_first_b = avg_elev(first_b_chunk, &ctx_first_b, &district_b);
let elev_interior_a = avg_elev(interior_a_chunk, &ctx_interior_a, &district_a);
let elev_interior_b = avg_elev(interior_b_chunk, &ctx_interior_b, &district_b);
// Seam step = elevation gap between the blended last-A chunk and the clean first-B chunk.
let seam_step = (elev_last_a - elev_first_b).unsigned_abs() as i64;
// Unblended step = elevation gap between pure interior chunks.
let interior_step = (elev_interior_a - elev_interior_b).unsigned_abs() as i64;
// Criterion 1: the seam step must be strictly less than the interior step.
// The blend reduces the apparent jump — if blending were absent the seam
// step would equal the interior step (both districts differ by 50 elev_q units).
assert!(
seam_step < interior_step,
"T-1042: cross-district seam step ({seam_step} m) must be < unblended \
interior step ({interior_step} m) — blend is not reducing the seam"
);
// Criterion 3: interior chunks produce IDENTICAL output to an unblended context.
// `ctx_interior_a` has blend_weight=255, secondary=None — same as the
// pre-T-1042 path. Derive twice; must match.
let ctx_interior_a2 = derive_chunk_context(seed, body, &district_a, interior_a_chunk, None);
for dx in 0..scale::VOXELS_PER_CHUNK {
let base_x = interior_a_chunk.0 * scale::CHUNK_M;
let base_y = interior_a_chunk.1 * scale::CHUNK_M;
let col1 = derive_voxel_column(
seed,
body,
&district_a,
&ctx_interior_a,
base_x + dx,
base_y,
);
let col2 = derive_voxel_column(
seed,
body,
&district_a,
&ctx_interior_a2,
base_x + dx,
base_y,
);
assert_eq!(
col1.elevation_m, col2.elevation_m,
"T-1042: interior chunk elevation must be deterministic across two derivations \
at voxel offset {dx}"
);
assert_eq!(
col1.terrain, col2.terrain,
"T-1042: interior chunk terrain must be deterministic at voxel offset {dx}"
);
}
}
#[test]
fn cross_district_morphology_family_seams_stay_sharp() {
// T-1042 Criterion 2: morphology family is NEVER blended across a district
// boundary (D-239 §7). An AlluvialPlain district adjacent to a FjordWall
// district must produce strictly AlluvialPlain (Soil terrain) in the
// last chunk of the alluvial district, even at 50-50 blend weight.
//
// The secondary district (FjordWall) has Rock terrain; the primary (Alluvial)
// has Soil. After blending, if family selection were inadvertently reading
// the secondary's zone, some tiles would switch to Rock — catch that here.
let district_alluvial = make_region(
MorphologyZone::AlluvialPlain,
TectonicClass::Stable,
GlaciationGrade::None,
5,
20,
0, // no channel — simpler tile layout for a clean terrain check
40,
Some(15.0),
VegetationClass::Forest,
);
let district_fjord = make_region(
MorphologyZone::Fjord,
TectonicClass::Active,
GlaciationGrade::Moderate,
55,
60,
28,
55,
Some(-8.0),
VegetationClass::Barren,
);
let (seed, body) = (99u64, "seam_sharp_test");
// Last chunk of the alluvial district — blend with the fjord at 50-50.
let boundary_chunk: ChunkPos = (31, 0);
let (_, blend_w) = district_boundary_blend_weight(boundary_chunk);
let ctx = derive_chunk_context(
seed,
body,
&district_alluvial,
boundary_chunk,
Some((&district_fjord, blend_w)),
);
// Every voxel in this chunk must have Soil terrain (AlluvialPlain primary family).
// If family dispatch accidentally picked up the secondary (FjordWall → Rock),
// this assertion fails.
let base_x = boundary_chunk.0 * scale::CHUNK_M;
let base_y = boundary_chunk.1 * scale::CHUNK_M;
for dy in (0..scale::VOXELS_PER_CHUNK).step_by(8) {
for dx in (0..scale::VOXELS_PER_CHUNK).step_by(8) {
let col = derive_voxel_column(
seed,
body,
&district_alluvial,
&ctx,
base_x + dx,
base_y + dy,
);
assert_eq!(
col.terrain,
TerrainMaterial::Soil,
"T-1042 §7 VIOLATED: cross-district boundary chunk must keep primary \
morphology (AlluvialPlain→Soil) at voxel ({},{}) — got {:?}",
base_x + dx,
base_y + dy,
col.terrain
);
}
}
}
#[test]
fn fjord_district_has_one_valley_spanning_chunks() {
// T-1041 (b): a FjordWall district contains ONE deep-water trough spanning
@@ -1126,7 +1365,7 @@ fn fjord_district_has_one_valley_spanning_chunks() {
);
let (seed, body) = (42u64, "fjord_body");
for district_chunk in [(640, -480), (-336, 992)] {
let probe = derive_chunk_context(seed, body, &district, district_chunk);
let probe = derive_chunk_context(seed, body, &district, district_chunk, None);
let ns = matches!(
probe.basin_direction,
BasinDirection::North | BasinDirection::South
@@ -1176,7 +1415,7 @@ fn gorge_district_has_one_valley_spanning_chunks() {
);
let (seed, body) = (42u64, "gorge_body");
for district_chunk in [(640, -480), (-336, 992)] {
let probe = derive_chunk_context(seed, body, &district, district_chunk);
let probe = derive_chunk_context(seed, body, &district, district_chunk, None);
let ns = matches!(
probe.basin_direction,
BasinDirection::North | BasinDirection::South
@@ -1231,7 +1470,7 @@ fn cliff_coast_one_continuous_coastline_per_region() {
);
let (seed, body) = (42u64, "cliff_body");
for district_chunk in [(656, -464), (-256, 768)] {
let probe = derive_chunk_context(seed, body, &district, district_chunk);
let probe = derive_chunk_context(seed, body, &district, district_chunk, None);
let coast = probe.coast_anchor_m;
let ns = matches!(
probe.basin_direction,
@@ -1305,7 +1544,7 @@ fn braided_threads_confined_to_region_belt() {
);
let (seed, body) = (17u64, "delta_body");
for district_chunk in [(800, -592)] {
let probe = derive_chunk_context(seed, body, &district, district_chunk);
let probe = derive_chunk_context(seed, body, &district, district_chunk, None);
let ns = matches!(
probe.basin_direction,
BasinDirection::North | BasinDirection::South
@@ -1359,7 +1598,7 @@ fn derive_chunk_timed(
district: &DistrictProfile,
chunk_pos: (i32, i32),
) -> (usize, u128) {
let chunk = derive_chunk_context(seed, body_id, district, chunk_pos);
let chunk = derive_chunk_context(seed, body_id, district, chunk_pos, None);
let base_x = chunk_pos.0 * 64;
let base_y = chunk_pos.1 * 64;
let t0 = Instant::now();
@@ -1573,7 +1812,7 @@ fn budget_voxel_cache_lru_overhead() {
VegetationClass::Forest,
);
let chunk_pos = (2, 2);
let chunk = derive_chunk_context(seed, body_id, &district, chunk_pos);
let chunk = derive_chunk_context(seed, body_id, &district, chunk_pos, None);
let base_x = chunk_pos.0 * 64;
let base_y = chunk_pos.1 * 64;
@@ -1777,7 +2016,7 @@ fn validation_gloedberg_volcanic_immature_drainage() {
);
// Derive a voxel and check TerrainMaterial::Lava (§8 lithology law).
let chunk = derive_chunk_context(42, "GJ581c", &profile, (0, 0));
let chunk = derive_chunk_context(42, "GJ581c", &profile, (0, 0), None);
let col = derive_voxel_column(42, "GJ581c", &profile, &chunk, 100, 100);
assert_eq!(
col.terrain,
@@ -1907,7 +2146,7 @@ fn basin_is_ns(
district: &DistrictProfile,
district_chunk: ChunkPos,
) -> bool {
let probe = derive_chunk_context(seed, body_id, district, district_chunk);
let probe = derive_chunk_context(seed, body_id, district, district_chunk, None);
matches!(
probe.basin_direction,
BasinDirection::North | BasinDirection::South
@@ -1928,7 +2167,7 @@ fn anchor_band_chunks(
district: &DistrictProfile,
district_chunk: ChunkPos,
) -> Vec<ChunkPos> {
let probe = derive_chunk_context(seed, body_id, district, district_chunk);
let probe = derive_chunk_context(seed, body_id, district, district_chunk, None);
let anchor_idx = probe.channel_anchor_m.div_euclid(64);
let ns = matches!(
probe.basin_direction,
@@ -1963,7 +2202,7 @@ fn derive_at_cross_along(
) -> settled_reach_server::atlas::voxel::VoxelColumn {
let (tx, ty) = if ns { (cross, along) } else { (along, cross) };
let chunk_pos = (tx.div_euclid(64), ty.div_euclid(64));
let chunk = derive_chunk_context(seed, body_id, district, chunk_pos);
let chunk = derive_chunk_context(seed, body_id, district, chunk_pos, None);
derive_voxel_column(seed, body_id, district, &chunk, tx, ty)
}