GoogleEarthEnterpriseMetadata.js

import protobufMinimal from '../ThirdParty/protobuf-minimal.js';
import when from '../ThirdParty/when.js';
import buildModuleUrl from './buildModuleUrl.js';
import Check from './Check.js';
import Credit from './Credit.js';
import defaultValue from './defaultValue.js';
import defined from './defined.js';
import defineProperties from './defineProperties.js';
import GoogleEarthEnterpriseTileInformation from './GoogleEarthEnterpriseTileInformation.js';
import isBitSet from './isBitSet.js';
import loadAndExecuteScript from './loadAndExecuteScript.js';
import CesiumMath from './Math.js';
import Request from './Request.js';
import Resource from './Resource.js';
import RuntimeError from './RuntimeError.js';
import TaskProcessor from './TaskProcessor.js';

    function stringToBuffer(str) {
        var len = str.length;
        var buffer = new ArrayBuffer(len);
        var ui8 = new Uint8Array(buffer);
        for (var i = 0; i < len; ++i) {
            ui8[i] = str.charCodeAt(i);
        }

        return buffer;
    }

    // Decodes packet with a key that has been around since the beginning of Google Earth Enterprise
    var defaultKey = stringToBuffer('\x45\xf4\xbd\x0b\x79\xe2\x6a\x45\x22\x05\x92\x2c\x17\xcd\x06\x71\xf8\x49\x10\x46\x67\x51\x00\x42\x25\xc6\xe8\x61\x2c\x66\x29\x08\xc6\x34\xdc\x6a\x62\x25\x79\x0a\x77\x1d\x6d\x69\xd6\xf0\x9c\x6b\x93\xa1\xbd\x4e\x75\xe0\x41\x04\x5b\xdf\x40\x56\x0c\xd9\xbb\x72\x9b\x81\x7c\x10\x33\x53\xee\x4f\x6c\xd4\x71\x05\xb0\x7b\xc0\x7f\x45\x03\x56\x5a\xad\x77\x55\x65\x0b\x33\x92\x2a\xac\x19\x6c\x35\x14\xc5\x1d\x30\x73\xf8\x33\x3e\x6d\x46\x38\x4a\xb4\xdd\xf0\x2e\xdd\x17\x75\x16\xda\x8c\x44\x74\x22\x06\xfa\x61\x22\x0c\x33\x22\x53\x6f\xaf\x39\x44\x0b\x8c\x0e\x39\xd9\x39\x13\x4c\xb9\xbf\x7f\xab\x5c\x8c\x50\x5f\x9f\x22\x75\x78\x1f\xe9\x07\x71\x91\x68\x3b\xc1\xc4\x9b\x7f\xf0\x3c\x56\x71\x48\x82\x05\x27\x55\x66\x59\x4e\x65\x1d\x98\x75\xa3\x61\x46\x7d\x61\x3f\x15\x41\x00\x9f\x14\x06\xd7\xb4\x34\x4d\xce\x13\x87\x46\xb0\x1a\xd5\x05\x1c\xb8\x8a\x27\x7b\x8b\xdc\x2b\xbb\x4d\x67\x30\xc8\xd1\xf6\x5c\x8f\x50\xfa\x5b\x2f\x46\x9b\x6e\x35\x18\x2f\x27\x43\x2e\xeb\x0a\x0c\x5e\x10\x05\x10\xa5\x73\x1b\x65\x34\xe5\x6c\x2e\x6a\x43\x27\x63\x14\x23\x55\xa9\x3f\x71\x7b\x67\x43\x7d\x3a\xaf\xcd\xe2\x54\x55\x9c\xfd\x4b\xc6\xe2\x9f\x2f\x28\xed\xcb\x5c\xc6\x2d\x66\x07\x88\xa7\x3b\x2f\x18\x2a\x22\x4e\x0e\xb0\x6b\x2e\xdd\x0d\x95\x7d\x7d\x47\xba\x43\xb2\x11\xb2\x2b\x3e\x4d\xaa\x3e\x7d\xe6\xce\x49\x89\xc6\xe6\x78\x0c\x61\x31\x05\x2d\x01\xa4\x4f\xa5\x7e\x71\x20\x88\xec\x0d\x31\xe8\x4e\x0b\x00\x6e\x50\x68\x7d\x17\x3d\x08\x0d\x17\x95\xa6\x6e\xa3\x68\x97\x24\x5b\x6b\xf3\x17\x23\xf3\xb6\x73\xb3\x0d\x0b\x40\xc0\x9f\xd8\x04\x51\x5d\xfa\x1a\x17\x22\x2e\x15\x6a\xdf\x49\x00\xb9\xa0\x77\x55\xc6\xef\x10\x6a\xbf\x7b\x47\x4c\x7f\x83\x17\x05\xee\xdc\xdc\x46\x85\xa9\xad\x53\x07\x2b\x53\x34\x06\x07\xff\x14\x94\x59\x19\x02\xe4\x38\xe8\x31\x83\x4e\xb9\x58\x46\x6b\xcb\x2d\x23\x86\x92\x70\x00\x35\x88\x22\xcf\x31\xb2\x26\x2f\xe7\xc3\x75\x2d\x36\x2c\x72\x74\xb0\x23\x47\xb7\xd3\xd1\x26\x16\x85\x37\x72\xe2\x00\x8c\x44\xcf\x10\xda\x33\x2d\x1a\xde\x60\x86\x69\x23\x69\x2a\x7c\xcd\x4b\x51\x0d\x95\x54\x39\x77\x2e\x29\xea\x1b\xa6\x50\xa2\x6a\x8f\x6f\x50\x99\x5c\x3e\x54\xfb\xef\x50\x5b\x0b\x07\x45\x17\x89\x6d\x28\x13\x77\x37\x1d\xdb\x8e\x1e\x4a\x05\x66\x4a\x6f\x99\x20\xe5\x70\xe2\xb9\x71\x7e\x0c\x6d\x49\x04\x2d\x7a\xfe\x72\xc7\xf2\x59\x30\x8f\xbb\x02\x5d\x73\xe5\xc9\x20\xea\x78\xec\x20\x90\xf0\x8a\x7f\x42\x17\x7c\x47\x19\x60\xb0\x16\xbd\x26\xb7\x71\xb6\xc7\x9f\x0e\xd1\x33\x82\x3d\xd3\xab\xee\x63\x99\xc8\x2b\x53\xa0\x44\x5c\x71\x01\xc6\xcc\x44\x1f\x32\x4f\x3c\xca\xc0\x29\x3d\x52\xd3\x61\x19\x58\xa9\x7d\x65\xb4\xdc\xcf\x0d\xf4\x3d\xf1\x08\xa9\x42\xda\x23\x09\xd8\xbf\x5e\x50\x49\xf8\x4d\xc0\xcb\x47\x4c\x1c\x4f\xf7\x7b\x2b\xd8\x16\x18\xc5\x31\x92\x3b\xb5\x6f\xdc\x6c\x0d\x92\x88\x16\xd1\x9e\xdb\x3f\xe2\xe9\xda\x5f\xd4\x84\xe2\x46\x61\x5a\xde\x1c\x55\xcf\xa4\x00\xbe\xfd\xce\x67\xf1\x4a\x69\x1c\x97\xe6\x20\x48\xd8\x5d\x7f\x7e\xae\x71\x20\x0e\x4e\xae\xc0\x56\xa9\x91\x01\x3c\x82\x1d\x0f\x72\xe7\x76\xec\x29\x49\xd6\x5d\x2d\x83\xe3\xdb\x36\x06\xa9\x3b\x66\x13\x97\x87\x6a\xd5\xb6\x3d\x50\x5e\x52\xb9\x4b\xc7\x73\x57\x78\xc9\xf4\x2e\x59\x07\x95\x93\x6f\xd0\x4b\x17\x57\x19\x3e\x27\x27\xc7\x60\xdb\x3b\xed\x9a\x0e\x53\x44\x16\x3e\x3f\x8d\x92\x6d\x77\xa2\x0a\xeb\x3f\x52\xa8\xc6\x55\x5e\x31\x49\x37\x85\xf4\xc5\x1f\x26\x2d\xa9\x1c\xbf\x8b\x27\x54\xda\xc3\x6a\x20\xe5\x2a\x78\x04\xb0\xd6\x90\x70\x72\xaa\x8b\x68\xbd\x88\xf7\x02\x5f\x48\xb1\x7e\xc0\x58\x4c\x3f\x66\x1a\xf9\x3e\xe1\x65\xc0\x70\xa7\xcf\x38\x69\xaf\xf0\x56\x6c\x64\x49\x9c\x27\xad\x78\x74\x4f\xc2\x87\xde\x56\x39\x00\xda\x77\x0b\xcb\x2d\x1b\x89\xfb\x35\x4f\x02\xf5\x08\x51\x13\x60\xc1\x0a\x5a\x47\x4d\x26\x1c\x33\x30\x78\xda\xc0\x9c\x46\x47\xe2\x5b\x79\x60\x49\x6e\x37\x67\x53\x0a\x3e\xe9\xec\x46\x39\xb2\xf1\x34\x0d\xc6\x84\x53\x75\x6e\xe1\x0c\x59\xd9\x1e\xde\x29\x85\x10\x7b\x49\x49\xa5\x77\x79\xbe\x49\x56\x2e\x36\xe7\x0b\x3a\xbb\x4f\x03\x62\x7b\xd2\x4d\x31\x95\x2f\xbd\x38\x7b\xa8\x4f\x21\xe1\xec\x46\x70\x76\x95\x7d\x29\x22\x78\x88\x0a\x90\xdd\x9d\x5c\xda\xde\x19\x51\xcf\xf0\xfc\x59\x52\x65\x7c\x33\x13\xdf\xf3\x48\xda\xbb\x2a\x75\xdb\x60\xb2\x02\x15\xd4\xfc\x19\xed\x1b\xec\x7f\x35\xa8\xff\x28\x31\x07\x2d\x12\xc8\xdc\x88\x46\x7c\x8a\x5b\x22');

    /**
     * Provides metadata using the Google Earth Enterprise REST API. This is used by the GoogleEarthEnterpriseImageryProvider
     *  and GoogleEarthEnterpriseTerrainProvider to share metadata requests.
     *
     * @alias GoogleEarthEnterpriseMetadata
     * @constructor
     *
     * @param {Resource|String} resourceOrUrl The url of the Google Earth Enterprise server hosting the imagery
     *
     * @see GoogleEarthEnterpriseImageryProvider
     * @see GoogleEarthEnterpriseTerrainProvider
     *
     */
    function GoogleEarthEnterpriseMetadata(resourceOrUrl) {
        //>>includeStart('debug', pragmas.debug);
        Check.defined('resourceOrUrl', resourceOrUrl);
        //>>includeEnd('debug');

        var url = resourceOrUrl;

        if (typeof url !== 'string' && !(url instanceof Resource)) {
            //>>includeStart('debug', pragmas.debug);
            Check.typeOf.string('resourceOrUrl.url', resourceOrUrl.url);
            //>>includeEnd('debug');

            url = resourceOrUrl.url;
        }

        var resource = Resource.createIfNeeded(url);
        resource.appendForwardSlash();
        this._resource = resource;

        /**
         * True if imagery is available.
         * @type {Boolean}
         * @default true
         */
        this.imageryPresent = true;

        /**
         * True if imagery is sent as a protocol buffer, false if sent as plain images. If undefined we will try both.
         * @type {Boolean}
         * @default undefined
         */
        this.protoImagery = undefined;

        /**
         * True if terrain is available.
         * @type {Boolean}
         * @default true
         */
        this.terrainPresent = true;

        /**
         * Exponent used to compute constant to calculate negative height values.
         * @type {Number}
         * @default 32
         */
        this.negativeAltitudeExponentBias = 32;

        /**
         * Threshold where any numbers smaller are actually negative values. They are multiplied by -2^negativeAltitudeExponentBias.
         * @type {Number}
         * @default EPSILON12
         */
        this.negativeAltitudeThreshold = CesiumMath.EPSILON12;

        /**
         * Dictionary of provider id to copyright strings.
         * @type {Object}
         * @default {}
         */
        this.providers = {};

        /**
         * Key used to decode packets
         * @type {ArrayBuffer}
         */
        this.key = undefined;

        this._quadPacketVersion = 1;

        this._tileInfo = {};
        this._subtreePromises = {};

        var that = this;
        this._readyPromise = requestDbRoot(this)
            .then(function() {
                return that.getQuadTreePacket('', that._quadPacketVersion);
            })
            .then(function() {
                return true;
            })
            .otherwise(function(e) {
                var message = 'An error occurred while accessing ' + getMetadataResource(that, '', 1).url + '.';
                return when.reject(new RuntimeError(message));
            });
    }

    defineProperties(GoogleEarthEnterpriseMetadata.prototype, {
        /**
         * Gets the name of the Google Earth Enterprise server.
         * @memberof GoogleEarthEnterpriseMetadata.prototype
         * @type {String}
         * @readonly
         */
        url : {
            get : function() {
                return this._resource.url;
            }
        },

        /**
         * Gets the proxy used for metadata requests.
         * @memberof GoogleEarthEnterpriseMetadata.prototype
         * @type {Proxy}
         * @readonly
         */
        proxy : {
            get : function() {
                return this._resource.proxy;
            }
        },

        /**
         * Gets the resource used for metadata requests.
         * @memberof GoogleEarthEnterpriseMetadata.prototype
         * @type {Resource}
         * @readonly
         */
        resource: {
            get: function() {
                return this._resource;
            }
        },

        /**
         * Gets a promise that resolves to true when the metadata is ready for use.
         * @memberof GoogleEarthEnterpriseMetadata.prototype
         * @type {Promise.<Boolean>}
         * @readonly
         */
        readyPromise : {
            get : function() {
                return this._readyPromise;
            }
        }
    });

    /**
     * Converts a tiles (x, y, level) position into a quadkey used to request an image
     * from a Google Earth Enterprise server.
     *
     * @param {Number} x The tile's x coordinate.
     * @param {Number} y The tile's y coordinate.
     * @param {Number} level The tile's zoom level.
     *
     * @see GoogleEarthEnterpriseMetadata#quadKeyToTileXY
     */
    GoogleEarthEnterpriseMetadata.tileXYToQuadKey = function(x, y, level) {
        var quadkey = '';
        for (var i = level; i >= 0; --i) {
            var bitmask = 1 << i;
            var digit = 0;

            // Tile Layout
            // ___ ___
            //|   |   |
            //| 3 | 2 |
            //|-------|
            //| 0 | 1 |
            //|___|___|
            //

            if (!isBitSet(y, bitmask)) { // Top Row
                digit |= 2;
                if (!isBitSet(x, bitmask)) { // Right to left
                    digit |= 1;
                }
            } else if (isBitSet(x, bitmask)) { // Left to right
                digit |= 1;
            }

            quadkey += digit;
        }
        return quadkey;
    };

    /**
     * Converts a tile's quadkey used to request an image from a Google Earth Enterprise server into the
     * (x, y, level) position.
     *
     * @param {String} quadkey The tile's quad key
     *
     * @see GoogleEarthEnterpriseMetadata#tileXYToQuadKey
     */
    GoogleEarthEnterpriseMetadata.quadKeyToTileXY = function(quadkey) {
        var x = 0;
        var y = 0;
        var level = quadkey.length - 1;
        for (var i = level; i >= 0; --i) {
            var bitmask = 1 << i;
            var digit = +quadkey[level - i];

            if (isBitSet(digit, 2)) {  // Top Row
                if (!isBitSet(digit, 1)) { // // Right to left
                    x |= bitmask;
                }
            } else {
                y |= bitmask;
                if (isBitSet(digit, 1)) { // Left to right
                    x |= bitmask;
                }
            }
        }
        return {
            x : x,
            y : y,
            level : level
        };
    };

    GoogleEarthEnterpriseMetadata.prototype.isValid = function(quadKey) {
        var info = this.getTileInformationFromQuadKey(quadKey);
        if (defined(info)) {
            return info !== null;
        }

        var valid = true;
        var q = quadKey;
        var last;
        while (q.length > 1) {
            last = q.substring(q.length - 1);
            q = q.substring(0, q.length - 1);
            info = this.getTileInformationFromQuadKey(q);
            if (defined(info)) {
                if (!info.hasSubtree() &&
                    !info.hasChild(parseInt(last))) {
                    // We have no subtree or child available at some point in this node's ancestry
                    valid = false;
                }

                break;
            } else if (info === null) {
                // Some node in the ancestry was loaded and said there wasn't a subtree
                valid = false;
                break;
            }
        }

        return valid;
    };

    var taskProcessor = new TaskProcessor('decodeGoogleEarthEnterprisePacket', Number.POSITIVE_INFINITY);

    /**
     * Retrieves a Google Earth Enterprise quadtree packet.
     *
     * @param {String} [quadKey=''] The quadkey to retrieve the packet for.
     * @param {Number} [version=1] The cnode version to be used in the request.
     * @param {Request} [request] The request object. Intended for internal use only.
     *
     * @private
     */
    GoogleEarthEnterpriseMetadata.prototype.getQuadTreePacket = function(quadKey, version, request) {
        version = defaultValue(version, 1);
        quadKey = defaultValue(quadKey, '');
        var resource = getMetadataResource(this, quadKey, version, request);

        var promise = resource.fetchArrayBuffer();

        if (!defined(promise)) {
            return undefined; // Throttled
        }

        var tileInfo = this._tileInfo;
        var key = this.key;
        return promise
            .then(function(metadata) {
                var decodePromise = taskProcessor.scheduleTask({
                    buffer : metadata,
                    quadKey : quadKey,
                    type : 'Metadata',
                    key: key
                }, [metadata]);

                return decodePromise
                    .then(function(result) {
                        var root;
                        var topLevelKeyLength = -1;
                        if (quadKey !== '') {
                            // Root tile has no data except children bits, so put them into the tile info
                            topLevelKeyLength = quadKey.length + 1;
                            var top = result[quadKey];
                            root = tileInfo[quadKey];
                            root._bits |= top._bits;

                            delete result[quadKey];
                        }

                        // Copy the resulting objects into tileInfo
                        // Make sure we start with shorter quadkeys first, so we know the parents have
                        //  already been processed. Otherwise we can lose ancestorHasTerrain along the way.
                        var keys = Object.keys(result);
                        keys.sort(function(a, b) {
                            return a.length - b.length;
                        });
                        var keysLength = keys.length;
                        for (var i = 0; i < keysLength; ++i) {
                            var key = keys[i];
                            var r = result[key];
                            if (r !== null) {
                                var info = GoogleEarthEnterpriseTileInformation.clone(result[key]);
                                var keyLength = key.length;
                                if (keyLength === topLevelKeyLength) {
                                    info.setParent(root);
                                } else if(keyLength > 1){
                                    var parent = tileInfo[key.substring(0, key.length - 1)];
                                    info.setParent(parent);
                                }
                                tileInfo[key] = info;
                            } else {
                                tileInfo[key] = null;
                            }
                        }
                    });
            });
    };

    /**
     * Populates the metadata subtree down to the specified tile.
     *
     * @param {Number} x The tile X coordinate.
     * @param {Number} y The tile Y coordinate.
     * @param {Number} level The tile level.
     * @param {Request} [request] The request object. Intended for internal use only.
     *
     * @returns {Promise<GoogleEarthEnterpriseTileInformation>} A promise that resolves to the tile info for the requested quad key
     *
     * @private
     */
    GoogleEarthEnterpriseMetadata.prototype.populateSubtree = function(x, y, level, request) {
        var quadkey = GoogleEarthEnterpriseMetadata.tileXYToQuadKey(x, y, level);
        return populateSubtree(this, quadkey, request);
    };

    function populateSubtree(that, quadKey, request) {
        var tileInfo = that._tileInfo;
        var q = quadKey;
        var t = tileInfo[q];
        // If we have tileInfo make sure sure it is not a node with a subtree that's not loaded
        if (defined(t) && (!t.hasSubtree() || t.hasChildren())) {
            return t;
        }

        while ((t === undefined) && q.length > 1) {
            q = q.substring(0, q.length - 1);
            t = tileInfo[q];
        }

        var subtreeRequest;
        var subtreePromises = that._subtreePromises;
        var promise = subtreePromises[q];
        if (defined(promise)) {
            return promise
                .then(function() {
                    // Recursively call this in case we need multiple subtree requests
                    subtreeRequest = new Request({
                        throttle : request.throttle,
                        throttleByServer : request.throttleByServer,
                        type : request.type,
                        priorityFunction : request.priorityFunction
                    });
                    return populateSubtree(that, quadKey, subtreeRequest);
                });
        }

        // t is either
        //   null so one of its parents was a leaf node, so this tile doesn't exist
        //   exists but doesn't have a subtree to request
        //   undefined so no parent exists - this shouldn't ever happen once the provider is ready
        if (!defined(t) || !t.hasSubtree()) {
            return when.reject(new RuntimeError('Couldn\'t load metadata for tile ' + quadKey));
        }

        // We need to split up the promise here because when will execute syncronously if getQuadTreePacket
        //  is already resolved (like in the tests), so subtreePromises will never get cleared out.
        //  Only the initial request will also remove the promise from subtreePromises.
        promise = that.getQuadTreePacket(q, t.cnodeVersion, request);
        if (!defined(promise)) {
            return undefined;
        }
        subtreePromises[q] = promise;

        return promise
            .then(function() {
                // Recursively call this in case we need multiple subtree requests
                subtreeRequest = new Request({
                    throttle : request.throttle,
                    throttleByServer : request.throttleByServer,
                    type : request.type,
                    priorityFunction : request.priorityFunction
                });
                return populateSubtree(that, quadKey, subtreeRequest);
            })
            .always(function() {
                delete subtreePromises[q];
            });
    }

    /**
     * Gets information about a tile
     *
     * @param {Number} x The tile X coordinate.
     * @param {Number} y The tile Y coordinate.
     * @param {Number} level The tile level.
     * @returns {GoogleEarthEnterpriseTileInformation|undefined} Information about the tile or undefined if it isn't loaded.
     *
     * @private
     */
    GoogleEarthEnterpriseMetadata.prototype.getTileInformation = function(x, y, level) {
        var quadkey = GoogleEarthEnterpriseMetadata.tileXYToQuadKey(x, y, level);
        return this._tileInfo[quadkey];
    };

    /**
     * Gets information about a tile from a quadKey
     *
     * @param {String} quadkey The quadkey for the tile
     * @returns {GoogleEarthEnterpriseTileInformation|undefined} Information about the tile or undefined if it isn't loaded.
     *
     * @private
     */
    GoogleEarthEnterpriseMetadata.prototype.getTileInformationFromQuadKey = function(quadkey) {
        return this._tileInfo[quadkey];
    };

    function getMetadataResource(that, quadKey, version, request) {
        return that._resource.getDerivedResource({
            url: 'flatfile?q2-0' + quadKey + '-q.' + version.toString(),
            request: request
        });
    }

    var dbrootParser;
    var dbrootParserPromise;
    function requestDbRoot(that) {
        var resource = that._resource.getDerivedResource({
            url: 'dbRoot.v5',
            queryParameters: {
                output: 'proto'
            }
        });

        if (!defined(dbrootParserPromise)) {
            var url = buildModuleUrl('ThirdParty/google-earth-dbroot-parser.js');
            var oldValue = window.cesiumGoogleEarthDbRootParser;
            dbrootParserPromise = loadAndExecuteScript(url)
                .then(function() {
                    dbrootParser = window.cesiumGoogleEarthDbRootParser(protobufMinimal);
                    if (defined(oldValue)) {
                        window.cesiumGoogleEarthDbRootParser = oldValue;
                    } else {
                        delete window.cesiumGoogleEarthDbRootParser;
                    }
                });
        }

        return dbrootParserPromise.then(function() {
            return resource.fetchArrayBuffer();
            }).then(function(buf) {
                var encryptedDbRootProto = dbrootParser.EncryptedDbRootProto.decode(new Uint8Array(buf));

                var byteArray = encryptedDbRootProto.encryptionData;
                var offset = byteArray.byteOffset;
                var end = offset + byteArray.byteLength;
                var key = that.key = byteArray.buffer.slice(offset, end);

                byteArray = encryptedDbRootProto.dbrootData;
                offset = byteArray.byteOffset;
                end = offset + byteArray.byteLength;
                var dbRootCompressed = byteArray.buffer.slice(offset, end);
                return taskProcessor.scheduleTask({
                    buffer : dbRootCompressed,
                    type : 'DbRoot',
                    key: key
                }, [dbRootCompressed]);
            })
            .then(function(result) {
                var dbRoot = dbrootParser.DbRootProto.decode(new Uint8Array(result.buffer));
                that.imageryPresent = defaultValue(dbRoot.imageryPresent, that.imageryPresent);
                that.protoImagery = dbRoot.protoImagery;
                that.terrainPresent = defaultValue(dbRoot.terrainPresent, that.terrainPresent);
                if (defined(dbRoot.endSnippet) && defined(dbRoot.endSnippet.model)) {
                    var model = dbRoot.endSnippet.model;
                    that.negativeAltitudeExponentBias = defaultValue(model.negativeAltitudeExponentBias, that.negativeAltitudeExponentBias);
                    that.negativeAltitudeThreshold = defaultValue(model.compressedNegativeAltitudeThreshold, that.negativeAltitudeThreshold);
                }
                if (defined(dbRoot.databaseVersion)) {
                    that._quadPacketVersion = defaultValue(dbRoot.databaseVersion.quadtreeVersion, that._quadPacketVersion);
                }
                var providers = that.providers;
                var providerInfo = defaultValue(dbRoot.providerInfo, []);
                var count = providerInfo.length;
                for(var i=0;i<count;++i) {
                    var provider = providerInfo[i];
                    var copyrightString = provider.copyrightString;
                    if (defined(copyrightString)) {
                        providers[provider.providerId] = new Credit(copyrightString.value);
                    }
                }
            })
            .otherwise(function() {
                // Just eat the error and use the default values.
                console.log('Failed to retrieve ' + resource.url + '. Using defaults.');
                that.key = defaultKey;
            });
    }
export default GoogleEarthEnterpriseMetadata;