visgl / loaders.gl / 24139120841

// loaders.gl

// SPDX-License-Identifier: MIT

// Copyright (c) vis.gl contributors

import type {BinaryGeometry} from '@loaders.gl/schema';

/**

 * Information about a binary geometry

 */

export type BinaryGeometryInfo = {

  /** The GeoJSON style geometry type corresponding to this particular binary geometry */

  multiGeometryType:

    | 'Point'

    | 'LineString'

    | 'Polygon'

    | 'MultiPoint'

    | 'MultiLineString'

    | 'MultiPolygon';

  /** Is this a "Multi" version of the binary geometry? */

  isMultiGeometry: boolean;

  /** How many dimensions are the coordinates? */

  dimension: number;

  /** How many points does this geometry have? */

  pointCount: number;

  /** How many coordinates does this geometry have? */

  coordinateCount: number;

};

/**

 * @returns information about a binary geometry

 */

export function getBinaryGeometryInfo(geometry: BinaryGeometry): BinaryGeometryInfo {

  return {

    isMultiGeometry: isMultiGeometryType(geometry),

    multiGeometryType: getMultiGeometryType(geometry),

    dimension: geometry.positions.size,

    pointCount: geometry.positions.value.length / geometry.positions.size,

    coordinateCount: geometry.positions.value.length

  };

}

/** @returns true if a binary geometry corresponds to a MultiPoint, MultiLineString or MultiPolygon */

function isMultiGeometryType(geometry: BinaryGeometry) {

  switch (geometry.type) {

    case 'Point':

      const {positions} = geometry;

      return positions.value.length / positions.size > 1;

    case 'LineString':

      const {pathIndices} = geometry;

      return pathIndices.value.length > 1;

    case 'Polygon':

      const {polygonIndices} = geometry;

      return polygonIndices.value.length > 1;

    default:

      return false;

  }

}

function getMultiGeometryType(geometry: BinaryGeometry) {

  const isMulti = isMultiGeometryType(geometry);

  switch (geometry.type) {

    case 'Point':

      return isMulti ? 'MultiPoint' : 'Point';

    case 'LineString':

      return isMulti ? 'MultiLineString' : 'LineString';

    case 'Polygon':

      return isMulti ? 'MultiPolygon' : 'Polygon';

    default:

      // @ts-expect-error

      throw new Error(`Illegal geometry type: ${type}`);

  }

}