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// proj4.defs("EPSG:4544", "+proj=tmerc +lat_0=0 +lon_0=105 +k=1 +x_0=500000 +y_0=0 +ellps=GRS80 +units=m +no_defs +type=crs");
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var proj4 = null;
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var webMercator = null;
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// const epst4326 = proj4.defs("EPSG:4326");
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/**
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* The map projection used by Google Maps, Bing Maps, and most of ArcGIS Online, EPSG:3857. This
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* projection use longitude and latitude expressed with the WGS84 and transforms them to Mercator using
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* the spherical (rather than ellipsoidal) equations.
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*
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* @alias CustomMercatorProjection
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* @constructor
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*
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* @param {Object} customEPSG 自定义的proj.defs对象，如proj4.defs("EPSG:4544")
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* @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid.
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*
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* @see GeographicProjection
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*/
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var Cesium = null;
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function CustomMercatorProjection(customEPSG, ellipsoid,CesiumN,proj) {
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Cesium = CesiumN;
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proj4 = proj;
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webMercator = proj4.defs('EPSG:3857');
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this._ellipsoid = Cesium.defaultValue(ellipsoid, Cesium.Ellipsoid.WGS84);
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this._semimajorAxis = this._ellipsoid.maximumRadius;
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this._oneOverSemimajorAxis = 1.0 / this._semimajorAxis;
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this._customEPSG = customEPSG;
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}
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Object.defineProperties(CustomMercatorProjection.prototype, {
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/**
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* Gets the {@link Ellipsoid}.
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*
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* @memberof CustomMercatorProjection.prototype
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*
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* @type {Ellipsoid}
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* @readonly
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*/
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ellipsoid: {
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get: function () {
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return this._ellipsoid;
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},
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},
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});
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/**
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* Converts a Mercator angle, in the range -PI to PI, to a geodetic latitude
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* in the range -PI/2 to PI/2.
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*
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* @param {Number} mercatorAngle The angle to convert.
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* @returns {Number} The geodetic latitude in radians.
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*/
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CustomMercatorProjection.mercatorAngleToGeodeticLatitude = function (
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mercatorAngle
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) {
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return (Math.PI / 2.0) - 2.0 * Math.atan(Math.exp(-mercatorAngle));
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};
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/**
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* Converts a geodetic latitude in radians, in the range -PI/2 to PI/2, to a Mercator
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* angle in the range -PI to PI.
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*
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* @param {Number} latitude The geodetic latitude in radians.
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* @returns {Number} The Mercator angle.
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*/
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CustomMercatorProjection.geodeticLatitudeToMercatorAngle = function (latitude) {
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// Clamp the latitude coordinate to the valid Mercator bounds.
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if (latitude > CustomMercatorProjection.MaximumLatitude) {
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latitude = CustomMercatorProjection.MaximumLatitude;
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} else if (latitude < -CustomMercatorProjection.MaximumLatitude) {
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latitude = -CustomMercatorProjection.MaximumLatitude;
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}
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const sinLatitude = Math.sin(latitude);
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return 0.5 * Math.log((1.0 + sinLatitude) / (1.0 - sinLatitude));
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};
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/**
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* The maximum latitude (both North and South) supported by a Web Mercator
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* (EPSG:3857) projection. Technically, the Mercator projection is defined
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* for any latitude up to (but not including) 90 degrees, but it makes sense
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* to cut it off sooner because it grows exponentially with increasing latitude.
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* The logic behind this particular cutoff value, which is the one used by
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* Google Maps, Bing Maps, and Esri, is that it makes the projection
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* square. That is, the rectangle is equal in the X and Y directions.
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*
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* The constant value is computed by calling:
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* CustomMercatorProjection.mercatorAngleToGeodeticLatitude(Math.PI)
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*
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* @type {Number}
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*/
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CustomMercatorProjection.MaximumLatitude = CustomMercatorProjection.mercatorAngleToGeodeticLatitude(
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Math.PI
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);
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/**
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* Converts geodetic ellipsoid coordinates, in radians, to the equivalent Web Mercator
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* X, Y, Z coordinates expressed in meters and returned in a {@link Cartesian3}. The height
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* is copied unmodified to the Z coordinate.
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*
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* @param {Cartographic} cartographic The cartographic coordinates in radians.
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* @param {Cartesian3} [result] The instance to which to copy the result, or undefined if a
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* new instance should be created.
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* @returns {Cartesian3} The equivalent web mercator X, Y, Z coordinates, in meters.
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*/
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CustomMercatorProjection.prototype.project = function (cartographic, result) {
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const semimajorAxis = this._semimajorAxis;
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const x1 = cartographic.longitude * semimajorAxis;
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const y1 =
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CustomMercatorProjection.geodeticLatitudeToMercatorAngle(
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cartographic.latitude
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) * semimajorAxis;
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const z = cartographic.height;
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const projectPos = proj4(webMercator,this._customEPSG, [x1,y1]);
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if (!Cesium.defined(result)) {
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return new Cesium.Cartesian3(projectPos[0], projectPos[1], z);
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}
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result.x = projectPos[0];
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result.y = projectPos[1];
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result.z = z;
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return result;
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};
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/**
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* Converts Web Mercator X, Y coordinates, expressed in meters, to a {@link Cartographic}
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* containing geodetic ellipsoid coordinates. The Z coordinate is copied unmodified to the
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* height.
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*
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* @param {Cartesian3} cartesian The web mercator Cartesian position to unrproject with height (z) in meters.
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* @param {Cartographic} [result] The instance to which to copy the result, or undefined if a
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* new instance should be created.
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* @returns {Cartographic} The equivalent cartographic coordinates.
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*/
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CustomMercatorProjection.prototype.unproject = function (cartesian, result) {
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//>>includeStart('debug', pragmas.debug);
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if (!Cesium.defined(cartesian)) {
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throw new Cesium.DeveloperError("cartesian is required");
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}
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//>>includeEnd('debug');
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const unprojectPos = proj4(this._customEPSG, webMercator, [cartesian.x, cartesian.y]);
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const oneOverEarthSemimajorAxis = this._oneOverSemimajorAxis;
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const longitude = unprojectPos[0] * oneOverEarthSemimajorAxis;
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const latitude = CustomMercatorProjection.mercatorAngleToGeodeticLatitude(
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unprojectPos[1] * oneOverEarthSemimajorAxis
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);
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const height = cartesian.z;
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if (!Cesium.defined(result)) {
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return new Cesium.Cartographic(longitude, latitude, height);
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}
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result.longitude = longitude;
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result.latitude = latitude;
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result.height = height;
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return result;
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};
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export default CustomMercatorProjection;
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