@bis-toolkit/bcn

Block Compression (BC1-BC5, BC7) texture decoders for TypeScript.

Features

• BC1 (DXT1): RGB/RGBA compression with 1-bit alpha
• BC2 (DXT3): RGBA compression with explicit alpha
• BC3 (DXT5): RGBA compression with interpolated alpha
• BC4: Single channel compression
• BC5: Two channel compression (normal maps)
• BC6H: HDR compression (not yet implemented - complex 14-mode HDR format)
• BC7: High quality RGBA compression

Installation

npm install @bis-toolkit/bcn

Usage

import { decodeBC1, decodeBC3, decodeBC7 } from '@bis-toolkit/bcn';

// Decode BC7 compressed data
const rgba = decodeBC7(compressedData, width, height);

// Decode BC1 (DXT1)
const rgba = decodeBC1(compressedData, width, height);

// Decode BC3 (DXT5)
const rgba = decodeBC3(compressedData, width, height);

All decoders return a Uint8Array containing RGBA data (4 bytes per pixel).

API

decodeBC1(data: DataView, width: number, height: number, useAlpha?: boolean): Uint8Array

decodeBC2(data: DataView, width: number, height: number): Uint8Array

decodeBC3(data: DataView, width: number, height: number): Uint8Array

decodeBC4(data: DataView, width: number, height: number, channel?: 'r' | 'g' | 'b' | 'a'): Uint8Array

decodeBC5(data: DataView, width: number, height: number, channel1?: 'r' | 'g' | 'b' | 'a', channel2?: 'r' | 'g' | 'b' | 'a'): Uint8Array

decodeBC7(data: DataView, width: number, height: number): Uint8Array

Note: BC6H (HDR) decoder is not yet implemented due to its complexity (14 modes with signed/unsigned variants).

Attribution

This library is a direct TypeScript port of BCnEncoder.NET, originally created by Nominom and licensed under the MIT License.

Copyright © 2025 Nominom
Licensed under the MIT License

License

GPLv3 © Alpine Labs - see LICENSE.

This work is derived from BCnEncoder.NET (MIT License) and is redistributed under GPLv3.