A loader for Basis Universal "supercompressed" GPU textures. Extracts supercompressed textures from the basis or ktx2 container and efficiently "transpiles" them into the specified compressed texture format.

Loader	Characteristic
File Format	Basis Universal
File Extension	`.basis`, `.ktx2`
File Type	Binary
Data Format	Array of compressed image data objects
Supported APIs	`load`, `parse`

Usage

import {BasisLoader} from '@loaders.gl/textures';
import {load} from '@loaders.gl/core';

const miplevels = await load(url, BasisLoader, options);
for (const compressedImage of miplevels) {
  ...
}

Options

Option	Type	Default	Description
`basis.format`	String	`'auto'`	Set to one of the supported compressed texture formats.
`basis.containerFormat`	String	`'auto'`	BasisLoader can decode KTX2 container. `ktx2` - decode data as KTX2 container with basis texture in it, `basis` - decode data as unwrapped basis texture, `auto` - detect KTX2 format by magic string
`basis.module`	String	`'transcoder'`	Possible values: `transcoder` or `encoder`. Selects wasm module to decode the texture. `transcoder` is smaller but supports only `BasisFile`. `encoder` supports `BasisFile` and `KTX2File`.

Wasm modules

BinomialLCC supplies 2 wasm modules:

basis_transcoder.wasm (~500 kB);
basis_encoder.wasm (~1,6 MB).

The modules are forked in the loaders.gl repo story: modules/textures/src/libs. The transcoder supports only .basis extension whereas the encoder supports .basis and .ktx2 extensions. So the encoder is used to decode .ktx2 files.

The libraries are loaded during runtime from URLs:

Compressed Texture Formats

The BasisLoader can transpile into the following compressed (and uncompressed) texture formats.

Format	Description
`etc1`
`etc2`
`bc1`
`bc3`
`bc4`
`bc5`
`bc7-m6-opaque-only`
`bc7-m5`
`pvrtc1-4-rgb`
`pvrtc1-4-rgba`
`astc-4x4`
`atc-rgb`
`atc-rgba-interpolated-alpha`
`rgba32`
`rgb565`
`bgr565`
`rgba4444`