@itwin/core-common
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iTwin.js components common to frontend and backend
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JavaScript
/*---------------------------------------------------------------------------------------------
* Copyright (c) Bentley Systems, Incorporated. All rights reserved.
* See LICENSE.md in the project root for license terms and full copyright notice.
*--------------------------------------------------------------------------------------------*/
/** @packageDocumentation
* @module Geometry
*/
import { Geometry } from "@itwin/core-geometry";
/** This class defines the mathematical model of the Earth shape in the form of an ellipsoid.
* There are various ways to define an ellipsoid but we have retained the definition based on the polar and equatorial radiuses.
* The other ellipsoid properties, such as flattening and inverse flattening, can be obtained using
* the simple equations that are defined at:
* https://en.wikipedia.org/wiki/Flattening and https://en.wikipedia.org/wiki/Earth_ellipsoid.
* The present class only implements the definition of the ellipsoid. No processing is performed here. If ellipsoid based computation
* are required refer to [[Ellipsoid]] in core/geometry package.
* The class only serves to describe a geodetic ellipsoid and can be partially or fully defined.
* For a lot of purposes simply setting the id property is sufficient to describe the ellipsoid in most cases
* as the mathematical properties (equatorial and polar radiuses) will be often extracted from the dictionary
* of commonly known ellipsoids by the reprojection engine used.
* @public
*/
export class GeodeticEllipsoid {
/** Ellipsoid key name */
id;
/** Description of the ellipsoid */
description;
/** If true then indicates the definition is deprecated. It should then be used for backward compatibility only.
* If false then the definition is not deprecated. Default is false.
*/
deprecated;
/** The textual description of the source of the ellipsoid definition. */
source;
/** The EPSG code of the ellipsoid. If undefined then there is no EPSG code associated. */
epsg;
/** The equatorial radius of the ellipsoid in meters. */
equatorialRadius;
/** The polar radius of the ellipsoid in meters. */
polarRadius;
constructor(data) {
this.deprecated = false;
if (data) {
this.id = data.id;
this.description = data.description;
this.deprecated = data.deprecated ?? false;
this.source = data.source;
this.epsg = data.epsg;
this.equatorialRadius = data.equatorialRadius;
this.polarRadius = data.polarRadius;
}
}
/** Creates a Geodetic Ellipsoid from JSON representation.
* @public */
static fromJSON(data) {
return new GeodeticEllipsoid(data);
}
/** Creates a JSON from the Geodetic Ellipsoid definition
* @public */
toJSON() {
const data = { equatorialRadius: this.equatorialRadius, polarRadius: this.polarRadius };
data.id = this.id;
data.description = this.description;
/* We prefer to use the default undef instead of false value for deprecated in Json */
data.deprecated = (this.deprecated === false ? undefined : true);
data.source = this.source;
data.epsg = this.epsg;
data.equatorialRadius = this.equatorialRadius;
data.polarRadius = this.polarRadius;
return data;
}
/** Compares two Geodetic Ellipsoid. It is a strict compare operation not an equivalence test
* but it applies a minuscule tolerance for floating point compares.
* It takes into account descriptive properties not only mathematical definition properties.
* @public */
equals(other) {
return this.id === other.id &&
this.description === other.description &&
this.deprecated === other.deprecated &&
this.source === other.source &&
this.epsg === other.epsg &&
Geometry.isAlmostEqualOptional(this.equatorialRadius, other.equatorialRadius, Geometry.smallMetricDistance) &&
Geometry.isAlmostEqualOptional(this.polarRadius, other.polarRadius, Geometry.smallMetricDistance);
}
}
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