@cesium/engine
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CesiumJS is a JavaScript library for creating 3D globes and 2D maps in a web browser without a plugin.
270 lines (240 loc) • 8.4 kB
JavaScript
import Check from "../Core/Check.js";
import clone from "../Core/clone.js";
import defined from "../Core/defined.js";
import Resource from "../Core/Resource.js";
import RuntimeError from "../Core/RuntimeError.js";
import hasExtension from "./hasExtension.js";
import ImplicitSubdivisionScheme from "./ImplicitSubdivisionScheme.js";
/**
* An ImplicitTileset is a simple struct that stores information about the
* structure of a single implicit tileset. This includes template URIs for
* locating resources, details from the implicit root tile (bounding volume,
* geometricError, etc.), and details about the subtrees (e.g. subtreeLevels,
* subdivisionScheme).
*
* @alias ImplicitTileset
* @constructor
*
* @param {Resource} baseResource The base resource for the tileset
* @param {object} tileJson The JSON header of the tile with either implicit tiling (3D Tiles 1.1) or the 3DTILES_implicit_tiling extension.
* @param {MetadataSchema} [metadataSchema] The metadata schema containing the implicit tile metadata class.
* @private
* @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
*/
function ImplicitTileset(baseResource, tileJson, metadataSchema) {
const implicitTiling = hasExtension(tileJson, "3DTILES_implicit_tiling")
? tileJson.extensions["3DTILES_implicit_tiling"]
: tileJson.implicitTiling;
//>>includeStart('debug', pragmas.debug);
Check.typeOf.object("implicitTiling", implicitTiling);
//>>includeEnd('debug');
/**
* The base resource for the tileset. This is stored here as it is needed
* later when expanding Implicit3DTileContents so tile URLs are relative
* to the tileset, not the subtree file.
*
* @type {Resource}
* @readonly
* @private
*/
this.baseResource = baseResource;
/**
* The geometric error of the root tile
*
* @type {number}
* @readonly
* @private
*/
this.geometricError = tileJson.geometricError;
/**
* The metadata schema containing the implicit tile metadata class.
*
* @type {MetadataSchema|undefined}
* @readonly
* @private
*/
this.metadataSchema = metadataSchema;
// Due to using explicit tile metadata to store a tight bounding box
// in some cases (see https://github.com/CesiumGS/cesium/pull/11365)
// it's important that this bounding volume is computed from the tile JSON
// (which is the original, possibly loose bounding volume) rather than
// tile.boundingVolume which is the tighter one.
const boundingVolume = tileJson.boundingVolume;
if (
!defined(boundingVolume.box) &&
!defined(boundingVolume.region) &&
!hasExtension(boundingVolume, "3DTILES_bounding_volume_S2") &&
!hasExtension(boundingVolume, "3DTILES_bounding_volume_cylinder")
) {
throw new RuntimeError(
"Only box, region, 3DTILES_bounding_volume_S2, and 3DTILES_bounding_volume_cylinder are supported for implicit tiling",
);
}
/**
* The JSON representation of a bounding volume. This is either a box or a
* region.
*
* @type {object}
* @readonly
* @private
*/
this.boundingVolume = boundingVolume;
/**
* The refine strategy as a string, either 'ADD' or 'REPLACE'
*
* @type {string}
* @readonly
* @private
*/
this.refine = tileJson.refine;
/**
* Template URI for the subtree resources, e.g.
* <code>https://example.com/{level}/{x}/{y}.subtree</code>
*
* @type {Resource}
* @readonly
* @private
*/
this.subtreeUriTemplate = new Resource({ url: implicitTiling.subtrees.uri });
/**
* Template URIs for locating content resources, e.g.
* <code>https://example.com/{level}/{x}/{y}.b3dm</code>.
* <p>
* This is an array to support multiple contents.
* </p>
*
* @type {Resource[]}
* @readonly
* @private
*/
this.contentUriTemplates = [];
/**
* Store a copy of the content headers, so properties such as
* <code>extras</code> or <code>extensions</code> are preserved when
* {@link Cesium3DTile}s are created for each tile.
* <p>
* This is an array to support multiple contents.
* </p>
*
* @type {Object[]}
* @readonly
* @private
*/
this.contentHeaders = [];
const contentHeaders = gatherContentHeaders(tileJson);
for (let i = 0; i < contentHeaders.length; i++) {
const contentHeader = contentHeaders[i];
this.contentHeaders.push(clone(contentHeader, true));
const contentResource = new Resource({ url: contentHeader.uri });
this.contentUriTemplates.push(contentResource);
}
/**
* The maximum number of contents as well as content availability bitstreams.
* This is used for loop bounds when checking content availability.
*
* @type {number}
* @readonly
* @private
*/
this.contentCount = this.contentHeaders.length;
/**
* Stores a copy of the root implicit tile's JSON header. This is used
* as a template for creating {@link Cesium3DTile}s. The following properties
* are removed:
*
* <ul>
* <li><code>tile.implicitTiling</code> to prevent infinite loops of implicit tiling</li>
* <li><code>tile.extensions["3DTILES_implicit_tiling"]</code>, if used instead of tile.implicitTiling</li>
* <li><code>tile.contents</code>, since contents are handled separately</li>
* <li><code>tile.content</code>, if used instead of tile.contents</li>
* <li><code>tile.extensions["3DTILES_multiple_contents"]</code>, if used instead of tile.contents or tile.content</li>
* </ul>
*
* @type {object}
* @readonly
* @private
*/
this.tileHeader = makeTileHeaderTemplate(tileJson);
/**
* The subdivision scheme for this implicit tileset; either OCTREE or QUADTREE
*
* @type {ImplicitSubdivisionScheme}
* @readonly
* @private
*/
this.subdivisionScheme =
ImplicitSubdivisionScheme[implicitTiling.subdivisionScheme];
/**
* The branching factor for this tileset. Either 4 for quadtrees or 8 for
* octrees.
*
* @type {number}
* @readonly
* @private
*/
this.branchingFactor = ImplicitSubdivisionScheme.getBranchingFactor(
this.subdivisionScheme,
);
/**
* How many distinct levels within each subtree. For example, a quadtree
* with subtreeLevels = 2 will have 5 nodes per quadtree (1 root + 4 children)
*
* @type {number}
* @readonly
* @private
*/
this.subtreeLevels = implicitTiling.subtreeLevels;
/**
* The number of levels containing available tiles in the tileset.
*
* @type {number}
* @readonly
* @private
*/
if (defined(implicitTiling.availableLevels)) {
this.availableLevels = implicitTiling.availableLevels;
} else {
this.availableLevels = implicitTiling.maximumLevel + 1;
}
}
/**
* Gather JSON headers for all contents in the tile.
* This handles both regular tiles and tiles with multiple contents, either
* in the contents array (3D Tiles 1.1) or the `3DTILES_multiple_contents` extension
*
* @param {object} tileJson The JSON header of the tile with either implicit tiling (3D Tiles 1.1) or the 3DTILES_implicit_tiling extension.
* @return {Object[]} An array of JSON headers for the contents of each tile
* @private
*/
function gatherContentHeaders(tileJson) {
if (hasExtension(tileJson, "3DTILES_multiple_contents")) {
const extension = tileJson.extensions["3DTILES_multiple_contents"];
return defined(extension.contents) ? extension.contents : extension.content;
}
if (defined(tileJson.contents)) {
return tileJson.contents;
}
if (defined(tileJson.content)) {
return [tileJson.content];
}
return [];
}
function makeTileHeaderTemplate(tileJson) {
const template = clone(tileJson, true);
// Remove the implicit tiling extension to prevent infinite loops,
// as well as content-related properties since content is handled separately
if (defined(template.extensions)) {
delete template.extensions["3DTILES_implicit_tiling"];
delete template.extensions["3DTILES_multiple_contents"];
// if there are no other extensions, remove the extensions property to
// keep each tile simple
if (Object.keys(template.extensions).length === 0) {
delete template.extensions;
}
}
delete template.implicitTiling;
delete template.contents;
delete template.content;
return template;
}
export default ImplicitTileset;