Archive Notice: babylonpress-ktx2-encoder

This repository has been moved.

The babylonpress-ktx2-encoder package is now maintained as part of the glb-optimizer-v2 monorepo.

New Location

📦 Package: glb-optimizer-v2/packages/babylonpress-ktx2-encoder

What This Means

• All future development, bug fixes, and releases will happen in the new location
• The standalone repository is now read-only and will not receive further updates
• The package name on npm (babylonpress-ktx2-encoder) remains unchanged
• Existing installations continue to work, but we recommend updating your imports or references to point to the new location if you're contributing

Why the Move

The package has been consolidated into the glb-optimizer-v2 monorepo to improve maintainability, enable better integration with related tools, and streamline the development workflow.

Getting Started

Visit the new package location for:

• Latest source code
• Updated documentation
• Issue tracking
• Contribution guidelines

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This repository was archived on July 06, 2026.

babylonpress-ktx2-encoder

KTX2 (.ktx2) encoding utilities for browser and Node.js applications, built on Basis Universal.

This package is maintained in the eldinor/ktx2-encoder fork and builds on the original work by Hu Song.

Install

npm install babylonpress-ktx2-encoder

What It Supports

• browser encoding
• browser worker encoding
• browser worker pool encoding for batch jobs
• Node.js encoding
• glTF-Transform integration

Browser

Direct encode

import { encodeToKTX2 } from "babylonpress-ktx2-encoder";

const png = new Uint8Array(await fetch("/texture.png").then((res) => res.arrayBuffer()));

const ktx2 = await encodeToKTX2(png, {
  isUASTC: true,
  generateMipmap: true
});

By default, the browser build resolves its bundled Basis JS and WASM assets automatically.

Single worker

Use worker: true when you want background encoding without changing the main API:

const ktx2 = await encodeToKTX2(png, {
  isUASTC: true,
  generateMipmap: true,
  worker: true
});

This is mainly about keeping the UI responsive. It usually does not make a single encode much faster.

Worker pool

Use a pool for batch conversion:

import { createKTX2WorkerPool, encodeToKTX2 } from "babylonpress-ktx2-encoder";

const pool = createKTX2WorkerPool({ size: 4 });

const ktx2 = await encodeToKTX2(png, {
  isUASTC: true,
  generateMipmap: true,
  worker: pool
});

const results = await pool.encodeMany([
  {
    imageBuffer: textureA,
    options: { isUASTC: true, generateMipmap: true }
  },
  {
    imageBuffer: textureB,
    options: { isUASTC: true, generateMipmap: true }
  }
]);

pool.terminate();

Pool size can be:

• omitted, which defaults to 2
• a number like 1, 2, 4
• "auto", which uses a conservative hardwareConcurrency heuristic

const pool = createKTX2WorkerPool({ size: "auto" });

Browser notes

• worker: true uses a shared default worker client
• worker encoding does not support a custom imageDecoder function
• wasmUrl and jsUrl can still be overridden when custom hosting is needed

Node.js

Node requires an imageDecoder for LDR inputs.

import fs from "node:fs/promises";
import sharp from "sharp";
import { encodeToKTX2 } from "babylonpress-ktx2-encoder";

async function imageDecoder(buffer: Uint8Array) {
  const image = sharp(buffer);
  const metadata = await image.metadata();
  const rawBuffer = await image.ensureAlpha().raw().toBuffer();

  return {
    width: metadata.width!,
    height: metadata.height!,
    data: new Uint8Array(rawBuffer)
  };
}

const png = new Uint8Array(await fs.readFile("./texture.png"));

const ktx2 = await encodeToKTX2(png, {
  isUASTC: true,
  generateMipmap: true,
  imageDecoder
});

glTF-Transform

import { ktx2 } from "babylonpress-ktx2-encoder/gltf-transform";

await document.transform(
  ktx2({
    isUASTC: true,
    generateMipmap: true
  })
);

Benchmark

A local benchmark page is included for comparing:

• main-thread encode
• single worker encode
• worker pool batch encode

Run it with:

npm run benchmark

The page is served from /benchmark/.

API

See API.md for a focused API reference.

Development

npm run build
npm test
npm run test:web
npm run test:gltf
npm run test:gltf:web
npm run test:coverage
npm run dev