Replace ol/Sphere with ol/sphere
This commit is contained in:
Tim Schaub
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src/ol/sphere.js
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255
src/ol/sphere.js
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/**
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* @license
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* Latitude/longitude spherical geodesy formulae taken from
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* http://www.movable-type.co.uk/scripts/latlong.html
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* Licensed under CC-BY-3.0.
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*/
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/**
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* @module ol/Sphere
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*/
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import {toRadians, toDegrees} from './math.js';
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import GeometryType from './geom/GeometryType.js';
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/**
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* Object literal with options for the {@link getLength} or
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* {@link getArea} functions.
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* @typedef {{projection: (ol.ProjectionLike|undefined),
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* radius: (number|undefined)}}
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*/
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export var SphereMetricOptions;
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/**
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* The mean Earth radius (1/3 * (2a + b)) for the WGS84 ellipsoid.
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* https://en.wikipedia.org/wiki/Earth_radius#Mean_radius
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* @type {number}
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*/
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export var DEFAULT_RADIUS = 6371008.8;
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/**
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* Get the great circle distance (in meters) between two geographic coordinates.
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* @param {Array} c1 Starting coordinate.
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* @param {Array} c2 Ending coordinate.
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* @param {number=} opt_radius The sphere radius to use. Defaults to the Earth's
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* mean radius using the WGS84 ellipsoid.
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* @return {number} The great circle distance between the points (in meters).
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* @api
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*/
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export function getDistance(c1, c2, opt_radius) {
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var radius = opt_radius || DEFAULT_RADIUS;
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var lat1 = toRadians(c1[1]);
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var lat2 = toRadians(c2[1]);
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var deltaLatBy2 = (lat2 - lat1) / 2;
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var deltaLonBy2 = toRadians(c2[0] - c1[0]) / 2;
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var a = Math.sin(deltaLatBy2) * Math.sin(deltaLatBy2) +
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Math.sin(deltaLonBy2) * Math.sin(deltaLonBy2) *
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Math.cos(lat1) * Math.cos(lat2);
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return 2 * radius * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
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}
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/**
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* Get the cumulative great circle length of linestring coordinates (geographic).
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* @param {Array} coordinates Linestring coordinates.
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* @param {number} radius The sphere radius to use.
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* @return {number} The length (in meters).
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*/
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function getLengthInternal(coordinates, radius) {
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var length = 0;
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for (var i = 0, ii = coordinates.length; i < ii - 1; ++i) {
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length += getDistance(coordinates[i], coordinates[i + 1], radius);
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}
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return length;
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}
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/**
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* Get the spherical length of a geometry. This length is the sum of the
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* great circle distances between coordinates. For polygons, the length is
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* the sum of all rings. For points, the length is zero. For multi-part
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* geometries, the length is the sum of the length of each part.
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* @param {ol.geom.Geometry} geometry A geometry.
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* @param {SphereMetricOptions=} opt_options Options for the length
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* calculation. By default, geometries are assumed to be in 'EPSG:3857'.
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* You can change this by providing a `projection` option.
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* @param {(ol.ProjectionLike|undefined)} opt_options.projection Projection of
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* the geometry. By default, the geometry is assumed to be in EPSG:3857
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* (Web Mercator).
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* @param {(number|undefined)} opt_options.radius Sphere radius. Defaults to
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* the Earth's mean radius using the WGS84 ellipsoid.
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* @return {number} The spherical length (in meters).
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* @api
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*/
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export function getLength(geometry, opt_options) {
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var options = opt_options || {};
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var radius = options.radius || DEFAULT_RADIUS;
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var projection = options.projection || 'EPSG:3857';
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var type = geometry.getType();
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if (type !== GeometryType.GEOMETRY_COLLECTION) {
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geometry = geometry.clone().transform(projection, 'EPSG:4326');
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}
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var length = 0;
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var coordinates, coords, i, ii, j, jj;
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switch (type) {
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case GeometryType.POINT:
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case GeometryType.MULTI_POINT: {
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break;
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}
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case GeometryType.LINE_STRING:
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case GeometryType.LINEAR_RING: {
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coordinates = /** @type {ol.geom.SimpleGeometry} */ (geometry).getCoordinates();
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length = getLengthInternal(coordinates, radius);
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break;
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}
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case GeometryType.MULTI_LINE_STRING:
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case GeometryType.POLYGON: {
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coordinates = /** @type {ol.geom.SimpleGeometry} */ (geometry).getCoordinates();
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for (i = 0, ii = coordinates.length; i < ii; ++i) {
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length += getLengthInternal(coordinates[i], radius);
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}
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break;
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}
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case GeometryType.MULTI_POLYGON: {
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coordinates = /** @type {ol.geom.SimpleGeometry} */ (geometry).getCoordinates();
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for (i = 0, ii = coordinates.length; i < ii; ++i) {
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coords = coordinates[i];
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for (j = 0, jj = coords.length; j < jj; ++j) {
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length += getLengthInternal(coords[j], radius);
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}
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}
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break;
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}
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case GeometryType.GEOMETRY_COLLECTION: {
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var geometries = /** @type {ol.geom.GeometryCollection} */ (geometry).getGeometries();
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for (i = 0, ii = geometries.length; i < ii; ++i) {
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length += getLength(geometries[i], opt_options);
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}
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break;
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}
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default: {
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throw new Error('Unsupported geometry type: ' + type);
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}
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}
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return length;
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}
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/**
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* Returns the spherical area for a list of coordinates.
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*
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* [Reference](https://trs-new.jpl.nasa.gov/handle/2014/40409)
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* Robert. G. Chamberlain and William H. Duquette, "Some Algorithms for
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* Polygons on a Sphere", JPL Publication 07-03, Jet Propulsion
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* Laboratory, Pasadena, CA, June 2007
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*
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* @param {Array.<ol.Coordinate>} coordinates List of coordinates of a linear
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* ring. If the ring is oriented clockwise, the area will be positive,
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* otherwise it will be negative.
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* @param {number} radius The sphere radius.
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* @return {number} Area (in square meters).
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*/
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function getAreaInternal(coordinates, radius) {
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var area = 0, len = coordinates.length;
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var x1 = coordinates[len - 1][0];
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var y1 = coordinates[len - 1][1];
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for (var i = 0; i < len; i++) {
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var x2 = coordinates[i][0], y2 = coordinates[i][1];
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area += toRadians(x2 - x1) *
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(2 + Math.sin(toRadians(y1)) +
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Math.sin(toRadians(y2)));
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x1 = x2;
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y1 = y2;
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}
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return area * radius * radius / 2.0;
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}
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/**
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* Get the spherical area of a geometry. This is the area (in meters) assuming
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* that polygon edges are segments of great circles on a sphere.
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* @param {ol.geom.Geometry} geometry A geometry.
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* @param {SphereMetricOptions=} opt_options Options for the area
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* calculation. By default, geometries are assumed to be in 'EPSG:3857'.
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* You can change this by providing a `projection` option.
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* @return {number} The spherical area (in square meters).
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* @api
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*/
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export function getArea(geometry, opt_options) {
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var options = opt_options || {};
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var radius = options.radius || DEFAULT_RADIUS;
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var projection = options.projection || 'EPSG:3857';
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var type = geometry.getType();
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if (type !== GeometryType.GEOMETRY_COLLECTION) {
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geometry = geometry.clone().transform(projection, 'EPSG:4326');
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}
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var area = 0;
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var coordinates, coords, i, ii, j, jj;
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switch (type) {
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case GeometryType.POINT:
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case GeometryType.MULTI_POINT:
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case GeometryType.LINE_STRING:
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case GeometryType.MULTI_LINE_STRING:
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case GeometryType.LINEAR_RING: {
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break;
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}
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case GeometryType.POLYGON: {
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coordinates = /** @type {ol.geom.Polygon} */ (geometry).getCoordinates();
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area = Math.abs(getAreaInternal(coordinates[0], radius));
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for (i = 1, ii = coordinates.length; i < ii; ++i) {
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area -= Math.abs(getAreaInternal(coordinates[i], radius));
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}
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break;
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}
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case GeometryType.MULTI_POLYGON: {
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coordinates = /** @type {ol.geom.SimpleGeometry} */ (geometry).getCoordinates();
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for (i = 0, ii = coordinates.length; i < ii; ++i) {
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coords = coordinates[i];
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area += Math.abs(getAreaInternal(coords[0], radius));
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for (j = 1, jj = coords.length; j < jj; ++j) {
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area -= Math.abs(getAreaInternal(coords[j], radius));
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}
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}
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break;
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}
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case GeometryType.GEOMETRY_COLLECTION: {
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var geometries = /** @type {ol.geom.GeometryCollection} */ (geometry).getGeometries();
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for (i = 0, ii = geometries.length; i < ii; ++i) {
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area += getArea(geometries[i], opt_options);
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}
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break;
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}
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default: {
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throw new Error('Unsupported geometry type: ' + type);
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}
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}
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return area;
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}
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/**
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* Returns the coordinate at the given distance and bearing from `c1`.
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*
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* @param {ol.Coordinate} c1 The origin point (`[lon, lat]` in degrees).
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* @param {number} distance The great-circle distance between the origin
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* point and the target point.
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* @param {number} bearing The bearing (in radians).
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* @param {number=} opt_radius The sphere radius to use. Defaults to the Earth's
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* mean radius using the WGS84 ellipsoid.
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* @return {ol.Coordinate} The target point.
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*/
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export function offset(c1, distance, bearing, opt_radius) {
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var radius = opt_radius || DEFAULT_RADIUS;
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var lat1 = toRadians(c1[1]);
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var lon1 = toRadians(c1[0]);
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var dByR = distance / radius;
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var lat = Math.asin(
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Math.sin(lat1) * Math.cos(dByR) +
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Math.cos(lat1) * Math.sin(dByR) * Math.cos(bearing));
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var lon = lon1 + Math.atan2(
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Math.sin(bearing) * Math.sin(dByR) * Math.cos(lat1),
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Math.cos(dByR) - Math.sin(lat1) * Math.sin(lat));
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return [toDegrees(lon), toDegrees(lat)];
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}
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