A new `world` generation domain in reikhelm-core, sibling to the dungeon
passes. Builds continuous fields (elevation, temperature, moisture, flow)
and classifies them into biomes — a general-purpose world generator any
game can consume, the foundation for the "generate a world for any game"
app idea.
Stages (each forks its own RNG sub-stream, like the dungeon pipeline):
- noise: own Perlin + fBm + domain warp (no `noise` crate, same reason
we own range/shuffle — version drift would change every seed)
- elevation: domain-warped fBm shaped by edge falloff + redistribution
- hydrology: ocean/lake flood, priority-flood depression fill, D8 flow
accumulation → dendritic rivers that always reach the sea
- climate: latitude temperature w/ altitude lapse; prevailing-wind
moisture sweep with orographic rain + emergent rain shadows
- biome: Whittaker classifier over temperature × moisture
Determinism: same (config, seed) → byte-identical World on every machine.
The whole generator is transcendental-free (only + - * / and comparisons),
so even the f32 fields reproduce exactly cross-platform (spec §7 ethos).
Plus `examples/world_png.rs`: a zero-dependency PNG exporter (hand-rolled
stored-DEFLATE zlib) with biome palette, ocean-depth shading, and hillshade
— a viewer for eyeballing output, kept out of the pure core.
24 new tests (determinism, rain-shadow, depression-filling, river density,
Whittaker corners); full suite 169 passing, clippy clean.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
The roadmap capstone: the dungeon is now populated.
- New entity layer: src/entity.rs (Entity { kind, at }, EntityKind {Entrance,
Exit, Treasure, Monster}); Map gains an `entities: Vec<Entity>` overlay field
(serde round-tripped). Entities aren't terrain, so no new Tile and the frozen
viz is untouched.
- EntityPlacer/EntityConfig: places one Entrance (random room), one Exit (the
room farthest from it — a traversal goal), per-room Treasure (treasure_chance)
and Monsters (monster_chance, 1..=max, never in the entrance room). All on
plain Floor only, never two per cell, fully deterministic.
- Handoff via the Blackboard (the designed side channel for non-tile/region/edge
data) under entity::BLACKBOARD_KEY, harvested by Pipeline into Map.entities —
so GenContext's 25 literals stay untouched.
- Renderer draws iconic markers on the final stage: green beacon (entrance),
cyan portal (exit), gold diamond (treasure), crimson eyed-blob (monster), each
with a soft glow. New entities toggle + treasure/monster sliders + readout.
Core: 135 tests green (6 new: one entrance/one exit on distinct floor, entrance
room monster-free, determinism, empty-map, recipe populated-check). clippy
clean. Pipeline is now 9 passes.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
