# Prefecture Map Generator v16 - Causal Terrain Cleanup Edition

This version is designed to run directly in VSCode with **Live Server**. No npm setup is required.

## Run

1. Open this folder in VSCode.
2. Right-click `index.html`.
3. Choose **Open with Live Server**.

## Main changes in v16

- River action is much stronger. `erosionField` and `depositionField` now produce clearer valleys, terraces, and alluvial lowlands.
- Neighboring prefecture regions are generated as background territory with `prefectureRegionId` and `regionalPrefectureBorders`, so the current prefecture is no longer visually isolated.
- River color now uses the same blue family as the sea; hierarchy is expressed by width and opacity.
- CBD/DID cells are sparser and restricted to dense, connected urban fabric.
- Railways, roads, and expressways are pruned for long-distance purpose; compact local tangles are rejected except for environmental ring segments.
- Expressway rings are rare. ICs are sampled at shorter intervals along expressway corridors.
- Bridge and tunnel icon rendering was removed. The legacy arrays remain empty for compatibility.
- Municipal regions are less likely to split small urban areas, while large cities claim larger municipality-like areas.

## Existing systems retained

- River hierarchy: main rivers, tributaries, and small streams.
- Port classes: major, regional, fishing, lake.
- Major rail corridors first, then purposeful branches.
- Expressways avoid city centers; city access is represented through IC access roads.
- Castles are restricted to terrain/historical candidate sites.
- Default generated names and manual overrides are both managed in `names.js`.
- Continuous terrain rendering is always on.

## Editing place names

Edit `names.js`.

```js
export const CUSTOM_NAMES = {
  "city-0": "Aohara",
  "port-0": "Shirahama",
  "castle-0": "Kurono"
};
```

## Tests

Open `test.html` with Live Server to run the browser-side smoke tests, or run `node --check *.js` on the source files.