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beezm ea291eaab5 chat2/11: hydraulic erosion — the faithful droplet pass on the locked shape, render-only, judged off vs on
Step 0: tag terrain-shape-v1 on a59e52f (the frag_4-locked, gallery-confirmed state).

Core/Scripts/HydraulicErosion.cs is the reference's pass ported verbatim - the four governors
(250,000 droplets, lifetime 384, carve cap 15 m, deposit cap 6 m) on one net-displacement
ledger read both ways and PROVEN on exit (the CARVE-CAP / DEPOSIT-CAP violations throw), the
sea clamp (spawn rejected below sea, death at sea, both brushes skip below-sea cells, the 0.5 m
margin floor on the erode brush), the cone-weighted normalized brush shared by erode and
deposit, the droplet physics (inertia 0.35, capacity 4, min slope 0.02, erode 0.12, deposit
0.15, evaporation 0.004, gravity 4, brush 2), PCG32 seeded at seed + 9271, the crater
exclusion whole. Engine-free; every metres<->raw conversion through WorldScale (no literal
251 - the same multiply/divide, so bit-identical arithmetic).

Tools/Scripts/ErosionPass.cs is the caller (pass 2b): render field only (copied if aliased to
classify), governors clamped as the reference ConfigManager clamped them, the crater exclusion
passed through INERT (no crater => radius 0 => weight 1 everywhere; the reference's
"core < carve factor" warning dormant), and the FLOOD GUARD - render water pixels counted
before and after, any change throws. TerrainGenConfig gains Erosion (default OFF, the anchor
rule) and the governors/physics/crater fields. Pass2Result.WithHeight hands back the eroded
render field. ShadeRenderer is a pure-hillshade plate (land only) because the palette relief's
0.30 hillshade hides half-metre drainage. ErosionTool carries TerrainShapeV1 (the locked shape's
values, pinned once) and the batch: 4 gallery seeds x off/on at 8192, grayscale + .f32 +
relief + shade per field, a mid-slope 1024-px crop off/on (relief and shade), the stats.

Faithful first, no tune: at 8192 the pass touches ~88 % of land cells at a mean 0.14 m, carve
15.00 / deposit 6.00 m at the caps, 0.5 m mean on the massif with 18 % of its cells moved more
than a metre. It reads as dissected summits with radial gully fans and carve/deposit bands
along the slope breaks, not dendritic networks: droplets die of lifetime (170k of 224k) before
they converge. A lifetime probe at 4096 (scratch) shows 1536 and 4096 identical - every
droplet is dead of evaporation by ~1,300 steps - so lifetime is not the lever; droplet count
is. The mid-slope green->yellow transition is not softened at the faithful tune.

Oracle, all passing on 4 seeds: erosion OFF bit-identical to terrain-shape-v1 (the task-10
gallery dumps, 67 M cells each); classify bit-identical off vs on and == the pass-1 field;
region labeling + island tag identical; flood guard (27.5 M water pixels unchanged, every
seed); caps proven; tag/coastline; classify == raw; centre is land; eroded field
bit-identical across two runs.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013EY3ZTF6NwzF8ukBHQXSK7
2026-08-22 12:19:20 -04:00
Client Phase 0: clean project skeleton for the v2 rewrite 2026-08-19 20:21:12 -04:00
Core chat2/11: hydraulic erosion — the faithful droplet pass on the locked shape, render-only, judged off vs on 2026-08-22 12:19:20 -04:00
Server Phase 0: clean project skeleton for the v2 rewrite 2026-08-19 20:21:12 -04:00
Tools chat2/11: hydraulic erosion — the faithful droplet pass on the locked shape, render-only, judged off vs on 2026-08-22 12:19:20 -04:00
.gitattributes Phase 0: clean project skeleton for the v2 rewrite 2026-08-19 20:21:12 -04:00
.gitignore Phase 0: clean project skeleton for the v2 rewrite 2026-08-19 20:21:12 -04:00
islaApocalypse-v2.csproj Phase 0: clean project skeleton for the v2 rewrite 2026-08-19 20:21:12 -04:00
islaApocalypse-v2.sln Phase 0: clean project skeleton for the v2 rewrite 2026-08-19 20:21:12 -04:00
project.godot Move the user:// isolation warning out of project.godot 2026-08-19 21:31:12 -04:00
README.md Phase 2a: the faithful redistribution curve, re-measured against v2's own output 2026-08-20 01:38:10 -04:00

Isla Apocalypse — v2

The rewrite (D-049). A post-apocalyptic survival voxel game: one island, generated once offline, loaded by everyone.

Status: Phase 2 — shaping. Phase 0 laid the contracts and the tooling rails; Phase 1 ported the crown-jewel noise and pass 1 (the island's raw shape); chat2/01 added pass 2a — the height redistribution curve and shelf detail, re-calibrated against this repo's own output, with the two-height-field split and an automatic oracle.

Still no erosion, rivers, water bodies, crater carve, coast shelf, offshore islets, biomes, roads or mesher.


⚠ Two repos. Never one.

Repo Role
~/celerNexus/islaApocalypse-v2/ (this) The rewrite. Every line of new code is written here.
~/celerNexus/islaApocalypse/ READ-ONLY. The pre-rewrite prototype, archived at ab78883, tag pre-rewrite-reference. Ported FROM; never written to.
~/celerNexus/islaApocalypse-vault-v0.1/ The design vault — the source of truth for WHAT and WHY. The vault leads.

The old codebase is a spent quarry (D-050): mined, never tracked, never synced, never canon'd. Writing rewrite code into it would corrupt the very thing being ported from.

⚠ Runtime data isolation — do not weaken

This project pins its user:// directory away from the old prototype's, which holds the preserved reference seeds, blueprints and batches:

user:// → ~/.local/share/islaApocalypse-v2/          ← this project
          ~/.local/share/godot/app_userdata/islaApocalypse/   ← ⛔ the OLD prototype. Never touch.

Pinned two ways in project.godot — a distinct application/config/name and use_custom_user_dir + custom_user_dir_name. Both must stay.

⚠ Do not document this with a comment in project.godot — it will not survive.

Godot rewrites project.godot on import and STRIPS ALL COMMENTS, replacing the header with its own boilerplate. (Measured: a warning block written there was gone after the next --import. The settings survived; only the explanation was deleted.) So the warning lives here, and the guarantee is enforced by the probe below — which exits non-zero on a clash and therefore works in a pre-flight check, not just by eye.

After any change to the [application] block, re-run the probe:

Godot_v4.7.2-stable_mono_linux.x86_64 --headless \
  --path ~/celerNexus/islaApocalypse-v2 res://Tools/Scenes/UserDirProbe.tscn

Layout

Core/     math + data only, ENGINE-FREE   — depends on nothing above it
Server/   authoritative logic             — may use Core          (empty: not yet its phase)
Client/   rendering                       — may use Core          (empty: not yet its phase)
Tools/    the offline generator           — ⚠ may NOT use Client

Each layer has a README.md stating its role and its boundary. Read the one for the layer you are about to write in — they carry the reasons, not just the rules.

The contracts this phase establishes

  • ★★ The column model (D-053) — the world as a 2D grid of columns, each a stack of (material, thickness) runs. Air is the top run; there is no air-vs-solid height branch.Core/Scripts/Column.cs
  • The material schemas (D-054) — terrain and building, two schemas bridged by a transformation seam that is deliberately empty. Identity is a registry key, never an ordinal. Mesh style is per-origin, never a material property. → Core/Scripts/MaterialRegistry.cs
  • The scaling discipline — nothing uses a raw pixel number. → Core/Scripts/GenerationScale.cs
  • The vertical yardstick — ONE metres-per-raw-unit number, not three constants and twenty literals as the prototype had. → Core/Scripts/WorldScale.cs
  • The elevation profile — the 7-band redistribution curve, identity at and below sea, its knots measured rather than chosen. → Core/Scripts/HeightCurve.cs
  • The two-height-field split (D-046) — heightClassify is raw and is the oracle; height is curved and is what gets drawn. → Tools/Scripts/Pass2Result.cs
  • Tooling safety — every path env-overridable, deletion refused by code. → Core/Scripts/ToolingPaths.cs, Core/Scripts/FileSafety.cs

Build

dotnet build
Godot_v4.7.2-stable_mono_linux.x86_64 --headless --import --path .

Godot 4.7.2 (mono) · .NET 8 (net8.0) · Godot.NET.Sdk/4.7.2

The reference repo is Godot 4.7.1. This repo deliberately targets 4.7.2 — clean rewrite, current tooling. 4.7.1 is the port source, not a constraint on new code.

<RollForward>Major</RollForward> in the .csproj is load-bearing.

The target is net8.0 but this machine carries only a .NET 10 runtime. Without that property the generated runtimeconfig.json rolls forward by MINOR only and every run fails with "You must install .NET 8". This bites at run time, not build time — the build succeeds either way — so re-check the emitted runtimeconfig.json after any .csproj change.

What this phase is NOT

No mesher, no stratigraphy, no biomes, no water, no rivers, no erosion. The pipeline is 2D-maps-first (D-056): stages 15 are flat maps, gotten completely right before a single 3D vertex exists. Building the mesher before the data is right is the specific trap this rewrite exists to undo.

And the curve is a BASELINE, not a verdict. It is ported faithfully and calibrated honestly so that later reshaping has a control to be judged against. Whether this elevation profile — 60 % of land in the bottom 14 m, 4 % above the plateau — is the one the world wants is an open question the histograms exist to inform, not one this port has answered.