BasisLoader
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:
- https://unpkg.com/@loaders.gl/textures@{VERSION}/dist/libs/basis_transcoder.wasm
- https://unpkg.com/@loaders.gl/textures@{VERSION}/dist/libs/basis_transcoder.js
- https://unpkg.com/@loaders.gl/textures@${VERSION}/dist/libs/basis_encoder.wasm
- https://unpkg.com/@loaders.gl/textures@${VERSION}/dist/libs/basis_encoder.js
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 |