@loaders.gl/3d-tiles/src/lib/parsers/helpers/parse-3d-tile-header.ts

3D Tiles, an open standard for streaming massive heterogeneous 3D geospatial datasets.

// loaders.gl
// SPDX-License-Identifier: MIT AND Apache-2.0
// Copyright vis.gl contributors

// This file is derived from the Cesium code base under Apache 2 license
// See LICENSE.md and https://github.com/AnalyticalGraphicsInc/cesium/blob/master/LICENSE.md

import {Tiles3DTileContent} from '../../../types';

const SIZEOF_UINT32 = 4;

/* PARSE FIXED HEADER:
Populates
  magic, // identifies type of tile
  type, // String version of magic
  version,
  byteLength
 */
export function parse3DTileHeaderSync(
  tile: Tiles3DTileContent,
  arrayBuffer: ArrayBuffer,
  byteOffset: number = 0
) {
  const view = new DataView(arrayBuffer);

  tile.magic = view.getUint32(byteOffset, true);
  byteOffset += SIZEOF_UINT32;

  tile.version = view.getUint32(byteOffset, true);
  byteOffset += SIZEOF_UINT32;

  tile.byteLength = view.getUint32(byteOffset, true);
  byteOffset += SIZEOF_UINT32;

  // TODO - move version check into each tile parser?
  if (tile.version !== 1) {
    throw new Error(`3D Tile Version ${tile.version} not supported`);
  }

  return byteOffset; // Indicates where the parsing ended
}