@loaders.gl/3d-tiles/src/lib/encoders/encode-3d-tile-composite.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 {MAGIC_ARRAY} from '../constants';
import {encode3DTileHeader, encode3DTileByteLength} from './helpers/encode-3d-tile-header';

export function encodeComposite3DTile(tile, dataView, byteOffset, options, encode3DTile) {
  // Add default magic for this tile type
  tile = {magic: MAGIC_ARRAY.COMPOSITE, tiles: [], ...tile};

  const byteOffsetStart = byteOffset;

  byteOffset += encode3DTileHeader(tile, dataView, byteOffset);

  if (dataView) {
    dataView.setUint32(byteOffset, tile.tiles.length, true); // tilesLength
  }
  byteOffset += 4;

  for (let i = 0; i < tile.tiles.length; ++i) {
    byteOffset += encode3DTile(tile.tiles[i], dataView, byteOffset, options);
  }

  // Go "back" and rewrite the tile's `byteLength` now that we know the value
  encode3DTileByteLength(dataView, byteOffsetStart, byteOffset - byteOffsetStart);

  return byteOffset;
}