@giro3d/giro3d/utils/GeoJSONUtils.js

A JS/WebGL framework for 3D geospatial data visualization

/*
 * Copyright (c) 2015-2018, IGN France.
 * Copyright (c) 2018-2026, Giro3D team.
 * SPDX-License-Identifier: MIT
 */

import { Feature } from 'ol';
import { GeometryCollection, LineString, MultiLineString, MultiPoint, MultiPolygon, Point, Polygon } from 'ol/geom';

/**
 * Given a simple GeoJSON Geometry object, returns the flat coordinates
 *
 * @param geojson - GeoJSON geometry object
 * @returns Flat coordinates
 */
function toFlatCoordinates(geojson) {
  if (geojson.type === 'GeometryCollection') {
    throw new Error(`GeoJSON type '${geojson.type}' is not supported`);
  }
  return geojson.coordinates.flat(3);
}

/**
 * Creates a simple GeoJSON Geometry object from a list of 3D coordinates.
 *
 * @param flat3Coords - Coordinates
 * @param geometryType - Geometry type
 * @returns GeoJSON geometry object
 */
function fromFlat3Coordinates(flat3Coords, geometryType) {
  if (geometryType === 'GeometryCollection') {
    throw new Error(`GeoJSON type '${geometryType}' is not supported`);
  }
  switch (geometryType) {
    case 'Point':
      return {
        type: geometryType,
        coordinates: flat3Coords[0]
      };
    case 'LineString':
    case 'MultiPoint':
      return {
        type: geometryType,
        coordinates: flat3Coords
      };
    case 'Polygon':
    case 'MultiLineString':
      return {
        type: geometryType,
        coordinates: [flat3Coords]
      };
    case 'MultiPolygon':
      return {
        type: geometryType,
        coordinates: [[flat3Coords]]
      };
    default:
      throw new Error(`GeoJSON type '${geometryType}' is not supported`);
  }
}

/**
 * Creates a simple GeoJSON Geometry object from a list of flat coordinates.
 *
 * Prefer `fromFlat3Coordinates` if possible (quicker, no object creation).
 *
 * @param flatCoords - Coordinates
 * @param geometryType - Geometry type
 * @returns GeoJSON geometry object
 */
function fromFlatCoordinates(flatCoords, geometryType) {
  const coords = new Array(flatCoords.length / 3);
  for (let i = 0; i < flatCoords.length / 3; i += 1) {
    coords[i] = [flatCoords[i * 3 + 0], flatCoords[i * 3 + 1], flatCoords[i * 3 + 2]];
  }
  return fromFlat3Coordinates(coords, geometryType);
}
function getOpenLayersGeometry(geometry) {
  switch (geometry.type) {
    case 'Point':
      return new Point(geometry.coordinates);
    case 'MultiPoint':
      return new MultiPoint(geometry.coordinates);
    case 'LineString':
      return new LineString(geometry.coordinates);
    case 'MultiLineString':
      return new MultiLineString(geometry.coordinates);
    case 'Polygon':
      return new Polygon(geometry.coordinates);
    case 'MultiPolygon':
      return new MultiPolygon(geometry.coordinates);
    case 'GeometryCollection':
      return new GeometryCollection(geometry.geometries.map(getOpenLayersGeometry));
  }
}
function getOpenLayersFeature(feature) {
  return new Feature({
    geometry: getOpenLayersGeometry(feature.geometry)
  });
}
export default {
  toFlatCoordinates,
  fromFlat3Coordinates,
  fromFlatCoordinates,
  getOpenLayersFeature
};