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# CLAUDE.md |
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DF/RimWorld-style colony sim, Rust + Bevy 0.20 (newer than training data — check `docs/bevy/` before guessing APIs). |
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## User rules |
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- Code is `cargo fmt`ed; run it before committing. |
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- Commit after each logical chunk; short commit msgs. |
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- Minimal code comments. "Why" explanations go into a test asserting the behaviour, comment lives in the test. |
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- Track work in `tasks.md` (done + planned). |
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- This file: dense notes for Claude, not user facing. |
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## Layout |
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- `src/main.rs` app wiring: DefaultPlugins (nearest sampling, canvas `#bevy`, fit_canvas_to_parent), adds plugins. |
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- `src/world.rs` `Terrain` enum (index = tileset layer, `ALL` order matters; rock = Stone/IronOre/GoldOre, impassable), `Plant` enum (Tree; separate layer, adds move cost). `WorldMap` resource: per-tile terrain, `Option<Plant>`, height in meters (0..`MAX_HEIGHT`=100); row-major, (0,0)=bottom-left, y up. `move_cost(pos)` = terrain + plant cost (None = impassable); `step_cost(from,to)` adds `UPHILL_COST_PER_METER` × climb — use step_cost for anything that moves. `TILE_SIZE`=16 world units, `hash2` deterministic int hash. |
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- `src/noise.rs` seeded 2D gradient (Perlin-style, quintic fade) noise + `fbm` (octave i uses seed+i). Range [-1,1]. |
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- `src/worldgen.rs` `WorldGenPlugin` inserts `WorldSeed` + `WorldMap` (256x256) at build time and writes `WorldGenerated` message at Startup; R → seed+1, regenerate, write message. `generate(size, seed)`: elevation fbm → height (min-max normalised to meters) and deep/shallow/sand/rock by **quantile** thresholds (fixed terrain shares per seed); ore = quantiles of two ore noises among rock tiles (gold 3%, iron 10%); fertility fbm top 20% → soil; rivers; trees (forest noise top 35% → 45% tree chance, else 3%; only Grass/Soil, placed after rivers). Rivers: `FlowField` = priority flood from water + non-rock edge tiles over non-rock tiles, each tile gets a downstream neighbour (spills out of depressions at lowest rim); `pick_rivers` traces 40 random mountain-foot sources, keeps the 4 longest spaced ≥40 apart; `carve_river` → ShallowWater, wider downstream, never over rock/deep water. `largest_region` (4-conn flood of walkable), `spawn_tiles(map, n)` = BFS from largest-region tile nearest map center. Everything reacting to a new world runs `.run_if(on_message::<WorldGenerated>)`: tilemap refresh, colonist respawn, camera recenter, selection clear. |
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- `src/tilemap.rs` renders map as `TilemapChunk`s (bevy::sprite_render) of `CHUNK_SIZE`=64; chunk transform = chunk center (TilemapChunk is centered on its transform). Tile (x,y) world center = (pos+0.5)*TILE_SIZE, so map spans [0, size*TILE_SIZE]. Tileset is generated in code (no assets): stacked 16x16 layers -> `reinterpret_stacked_2d_as_array`. Per-tile tint via `TileData.color`. Two layers of chunks (`Layer::Terrain` z=0, `Layer::Plants` z=0.5, alpha blend, tree texture drawn in code), spawned once at Startup (`Chunk{origin, layer}`); terrain tint = jitter × `hillshade` (light from NW, `RELIEF` exaggeration) × height brightness, water unshaded; ore = stone texture with coloured specks; world changes overwrite `TilemapChunkTileData` in place (bevy's `update_tilemap_chunk_indices` re-uploads via change detection). |
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- `src/camera.rs` `CameraController` on Camera2d: WASD/arrows pan (shift = fast, speed scaled by ortho scale), middle/right drag pan (from cursor delta, not AccumulatedMouseMotion — that doesn't fire for web), scroll zoom toward cursor (`zoom_towards`), camera center clamped to world rect. |
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- `src/selection.rs` `Cursor` resource (screen/world/tile) and `Selection` enum (None/Tile/Colonist(Entity)). PostUpdate after `TransformSystems::Propagate` (fresh camera GlobalTransform). LMB: pick nearest colonist within `PICK_RADIUS` of cursor world pos, else tile, off-map clears; Esc clears. RMB click (press/release within `CLICK_SLOP_PX`, else it was a drag-pan) writes `MoveOrder` for selected colonist. Gizmos: hover rect, selected rect / colonist circle + remaining path linestrip. Top-left UI text (clock + speed/PAUSED, seed, hover, selection). Tests use headless `App` + `ButtonInput`/`Cursor` resources, `Messages<MoveOrder>::drain`. |
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- `src/pathfinding.rs` `find_path(map, start, goal) -> Option<Vec<UVec2>>` A*, 8-dir, no corner cutting, cost = (10|14) * `Terrain::move_cost` of entered tile (100 = normal, None = impassable), octile heuristic. Path excludes start, includes goal; start==goal → empty. |
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- `src/colonist.rs` `Colonist{name}` (spawned/respawned on `WorldGenerated` at `spawn_tiles`) requires `TilePos` (last reached tile), `Path(VecDeque)`, `Wander(Timer)`. `handle_move_orders` in Update (orders apply instantly even while paused; `repath` keeps tile being entered at front). FixedUpdate chain: `wander` (idle + timer → random goal within radius), `follow_path` (moves `SimPos`, speed / terrain cost, `step_towards`). Camera uses `Time<Real>` so it works while paused. Rendered as Mesh2d circles z=1. |
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- `src/sim.rs` `SimPlugin`: fixed timestep `Time<Fixed>` 60 Hz = sim ticks; all sim logic in `FixedUpdate` (Res<Time> there = fixed delta). `SimTick` counter (FixedFirst), `format_clock` (600 ticks/hour = 10 s real at 1x, starts Day 1 06:00). `SimSpeed` Normal/Fast/Fastest = 1x/3x/6x via `Time<Virtual>::set_relative_speed`; keys 1/2/3 set speed + unpause, Space toggles pause. Render interpolation: sim entities hold `SimPos` (+ `PrevSimPos`, copied in FixedFirst); `interpolate_transforms` lerps Transform by `overstep_fraction` in `RunFixedMainLoop`/AfterFixedMainLoop. Spawn with `sim_pos(v)` so prev==cur. Never write Transform of sim entities directly. |
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- `src/rng.rs` `SimRng` SplitMix64 resource, seeded (deterministic sim; no `rand` dep). |
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## Gotchas |
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- WebGL2 (wgpu GLES) guesses array texture view dim from layer count: 1→D2, 6→Cube, 6k→CubeArray. Tileset layer count padded via `tileset_layer_count`. Symptom: black screen + "wgpu-hal heuristics assumed ... Cube" errors. |
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- `UVec2::div_ceil` doesn't exist in this glam. |
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- No `rand` dep; use `SimRng` (stateful) or `hash2` (positional noise). |
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## Build / run |
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- Native: `cargo run`. Tests: `cargo test`. |
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- Web: `./scripts/build-web.sh [profile]` (default `wasm-release`, ~3.5 min cold) → `target/web/`. Needs wasm-bindgen-cli matching Cargo.lock `wasm-bindgen` version (currently 0.2.129, installed in ~/.cargo/bin). |
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- Browser verification: `.claude/launch.json` config `web` (python http.server :8080 serving target/web) → `preview_start name=web`, then screenshot/scroll in built-in browser. Synthetic JS pointer events are ignored by winit; real drags only via computer tool left_click_drag (left button) — temporarily bind Left to test drag code. computer tool `right_click` works for RMB clicks. Pause (Space) before clicking moving colonists. |
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- Browser pane screenshots can lag 1-2s behind the canvas (verified: rAF gaps ≤51ms while screenshot still showed old frame). Wait ≥3s after an action, or cross-check via hover text before concluding a render bug. |
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- Bevy logs in browser console; check for ERROR after load. Console log persists across reloads in the pane — count "Creating new window" lines to tell which load an error belongs to. |
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## Docs |
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- `docs/bevy/examples/` full 0.20 examples (e.g. `2d/tilemap_chunk.rs`, `camera/*`). `docs/bevy/release-content/` migration guides + release notes. |
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- Crate sources: `~/.cargo/registry/src/index.crates.io-*/bevy_*-0.20.0/`. |