@babylonjs/viewer/dist/chunks/gltf-feature-meshopt-Bdj0KhKJ.esm.js

The Babylon Viewer aims to simplify a specific but common Babylon.js use case: loading, viewing, and interacting with a 3D model.

import { T as ThrowLiteError, j as U8, ak as DV } from './index-By0tcgYN.esm.js';

let meshoptBaseUrl = "/";
let scriptLoadPromise = null;
function loadMeshoptScript() {
  if (scriptLoadPromise) {
    return scriptLoadPromise;
  }
  scriptLoadPromise = new Promise((resolve, reject) => {
    const existing = globalThis.MeshoptDecoder;
    if (existing) {
      resolve(existing);
      return;
    }
    const script = document.createElement("script");
    script.src = meshoptBaseUrl + "meshopt_decoder.js";
    script.onload = () => {
      const mod = globalThis.MeshoptDecoder;
      if (!mod) {
        reject(new Error("meshopt_decoder.js loaded but MeshoptDecoder is undefined"));
      } else {
        resolve(mod);
      }
    };
    script.onerror = () => reject(new Error("Failed to load meshopt_decoder.js from " + script.src));
    document.head.appendChild(script);
  });
  return scriptLoadPromise;
}
async function getMeshoptDecoder() {
  const mod = await loadMeshoptScript();
  await mod.ready;
  return mod;
}

function align4(n) {
  return n + 3 & -4;
}
const feature = {
  id: "EXT_meshopt_compression",
  async preParse(json, binChunk) {
    const bufferViews = json.bufferViews ?? [];
    const decoder = await getMeshoptDecoder();
    const materialized = new Array(bufferViews.length);
    const newOffsets = new Array(bufferViews.length);
    let total = 0;
    for (let i = 0; i < bufferViews.length; i++) {
      const bv = bufferViews[i];
      const ext = bv.extensions?.EXT_meshopt_compression;
      let bytes;
      if (ext) {
        if ((ext.buffer ?? 0) !== 0) {
          ThrowLiteError(86, ext.buffer);
        }
        const source = new U8(binChunk.buffer, binChunk.byteOffset + (ext.byteOffset ?? 0), ext.byteLength);
        const target = new U8(ext.count * ext.byteStride);
        decoder.decodeGltfBuffer(target, ext.count, ext.byteStride, source, ext.mode, ext.filter ?? "NONE");
        bytes = target;
      } else {
        if ((bv.buffer ?? 0) !== 0) {
          ThrowLiteError(87, bv.buffer);
        }
        bytes = new U8(binChunk.buffer.slice(binChunk.byteOffset + (bv.byteOffset ?? 0), binChunk.byteOffset + (bv.byteOffset ?? 0) + bv.byteLength));
      }
      materialized[i] = bytes;
      newOffsets[i] = total;
      total = align4(total + bytes.length);
    }
    const packed = new U8(total);
    for (let i = 0; i < bufferViews.length; i++) {
      const bv = bufferViews[i];
      packed.set(materialized[i], newOffsets[i]);
      bv.buffer = 0;
      bv.byteOffset = newOffsets[i];
      bv.byteLength = materialized[i].length;
      if (bv.extensions) {
        delete bv.extensions.EXT_meshopt_compression;
      }
    }
    return new DV(packed.buffer);
  }
};

export { feature as default };
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