SphereOutlineGeometry.js

/*global define*/
define([
        './Cartesian3',
        './defaultValue',
        './defined',
        './DeveloperError',
        './EllipsoidOutlineGeometry'
    ], function(
        Cartesian3,
        defaultValue,
        defined,
        DeveloperError,
        EllipsoidOutlineGeometry) {
    "use strict";

    /**
     * A description of the outline of a sphere.
     *
     * @alias SphereOutlineGeometry
     * @constructor
     *
     * @param {Object} [options] Object with the following properties:
     * @param {Number} [options.radius=1.0] The radius of the sphere.
     * @param {Number} [options.stackPartitions=10] The count of stacks for the sphere (1 greater than the number of parallel lines).
     * @param {Number} [options.slicePartitions=8] The count of slices for the sphere (Equal to the number of radial lines).
     * @param {Number} [options.subdivisions=200] The number of points per line, determining the granularity of the curvature .
     *
     * @exception {DeveloperError} options.stackPartitions must be greater than or equal to one.
     * @exception {DeveloperError} options.slicePartitions must be greater than or equal to zero.
     * @exception {DeveloperError} options.subdivisions must be greater than or equal to zero.
     *
     * @demo {@link http://cesiumjs.org/Cesium/Apps/Sandcastle/index.html?src=Sphere%20Outline.html|Cesium Sandcastle Sphere Outline Demo}
     *
     * @example
     * var sphere = new Cesium.SphereOutlineGeometry({
     *   radius : 100.0,
     *   stackPartitions : 6,
     *   slicePartitions: 5
     * });
     * var geometry = Cesium.SphereOutlineGeometry.createGeometry(sphere);
     */
    var SphereOutlineGeometry = function(options) {
        var radius = defaultValue(options.radius, 1.0);
        var radii = new Cartesian3(radius, radius, radius);
        var ellipsoidOptions = {
                radii: radii,
                stackPartitions: options.stackPartitions,
                slicePartitions: options.slicePartitions,
                subdivisions: options.subdivisions
        };

        this._ellipsoidGeometry = new EllipsoidOutlineGeometry(ellipsoidOptions);
        this._workerName = 'createSphereOutlineGeometry';
    };

    /**
     * The number of elements used to pack the object into an array.
     * @type {Number}
     */
    SphereOutlineGeometry.packedLength = EllipsoidOutlineGeometry.packedLength;

    /**
     * Stores the provided instance into the provided array.
     * @function
     *
     * @param {SphereOutlineGeometry} value The value to pack.
     * @param {Number[]} array The array to pack into.
     * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
     */
    SphereOutlineGeometry.pack = function(value, array, startingIndex) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(value)) {
            throw new DeveloperError('value is required');
        }
        //>>includeEnd('debug');

        EllipsoidOutlineGeometry.pack(value._ellipsoidGeometry, array, startingIndex);
    };

    var scratchEllipsoidGeometry = new EllipsoidOutlineGeometry();
    var scratchOptions = {
        radius : undefined,
        radii : new Cartesian3(),
        stackPartitions : undefined,
        slicePartitions : undefined,
        subdivisions : undefined
    };

    /**
     * Retrieves an instance from a packed array.
     *
     * @param {Number[]} array The packed array.
     * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
     * @param {SphereOutlineGeometry} [result] The object into which to store the result.
     * @returns {SphereOutlineGeometry} The modified result parameter or a new SphereOutlineGeometry instance if one was not provided.
     */
    SphereOutlineGeometry.unpack = function(array, startingIndex, result) {
        var ellipsoidGeometry = EllipsoidOutlineGeometry.unpack(array, startingIndex, scratchEllipsoidGeometry);
        scratchOptions.stackPartitions = ellipsoidGeometry._stackPartitions;
        scratchOptions.slicePartitions = ellipsoidGeometry._slicePartitions;
        scratchOptions.subdivisions = ellipsoidGeometry._subdivisions;

        if (!defined(result)) {
            scratchOptions.radius = ellipsoidGeometry._radii.x;
            return new SphereOutlineGeometry(scratchOptions);
        }

        Cartesian3.clone(ellipsoidGeometry._radii, scratchOptions.radii);
        result._ellipsoidGeometry = new EllipsoidOutlineGeometry(scratchOptions);
        return result;
    };

    /**
     * Computes the geometric representation of an outline of a sphere, including its vertices, indices, and a bounding sphere.
     *
     * @param {SphereOutlineGeometry} sphereGeometry A description of the sphere outline.
     * @returns {Geometry} The computed vertices and indices.
     */
    SphereOutlineGeometry.createGeometry = function(sphereGeometry) {
        return EllipsoidOutlineGeometry.createGeometry(sphereGeometry._ellipsoidGeometry);
    };

    return SphereOutlineGeometry;
});