@vectorstream/core

Topological core: half-edge structure, Euler operators, snap rounding, undo history, GeoJSON import and export. No DOM, no map.

The model underneath the editor: one planar partition in which every boundary exists once and is shared by the faces on both sides.

Install

npm install @vectorstream/core

Example

import {
  History,
  SpatialIndex,
  checkGeometry,
  importGeoJSON,
  insertPolygon,
  type FaceId,
  type FeatureCollection,
  type Partition,
  type Point,
} from '@vectorstream/core';

/**
 * The core without editor and map: a partition, a history, and an intent inside a transaction.
 * The editor does the same for every drawing, with the same checks.
 */
export function insertOutline(data: FeatureCollection, outline: Point[]): { partition: Partition; history: History; faces: FaceId[] } {
  const partition = importGeoJSON(data);
  const history = new History(partition, {
    checkInvariants: true, // structure: half-edge pairs, closed cycles, Euler's formula, …
    validators: [(p) => checkGeometry(p, new SpatialIndex(p), 0)], // geometry: crossings, overlaps
  });
  // All or nothing: if a check fails, the transaction is rolled back and throws.
  const faces = history.transaction('insert-outline', (tx) => insertPolygon(tx, outline));
  return { partition, history, faces };
}

Documentation

The handbook lives in docs/handbuch/ of the vectorstream repository; a public address follows with the first release.

License

MIT, see LICENSE.