threejs/examples/jsm/loaders/LUTCubeLoader.js

// https://wwwimages2.adobe.com/content/dam/acom/en/products/speedgrade/cc/pdfs/cube-lut-specification-1.0.pdf

import {
	Loader,
	FileLoader,
	Vector3,
	DataTexture,
	Data3DTexture,
	UnsignedByteType,
	ClampToEdgeWrapping,
	LinearFilter,
} from 'three';

export class LUTCubeLoader extends Loader {

	load( url, onLoad, onProgress, onError ) {

		const loader = new FileLoader( this.manager );
		loader.setPath( this.path );
		loader.setResponseType( 'text' );
		loader.load( url, text => {

			try {

				onLoad( this.parse( text ) );

			} catch ( e ) {

				if ( onError ) {

					onError( e );

				} else {

					console.error( e );

				}

				this.manager.itemError( url );

			}

		}, onProgress, onError );

	}

	parse( str ) {

		// Remove empty lines and comments
		str = str
			.replace( /^#.*?(\n|\r)/gm, '' )
			.replace( /^\s*?(\n|\r)/gm, '' )
			.trim();

		let title = null;
		let size = null;
		const domainMin = new Vector3( 0, 0, 0 );
		const domainMax = new Vector3( 1, 1, 1 );

		const lines = str.split( /[\n\r]+/g );
		let data = null;

		let currIndex = 0;
		for ( let i = 0, l = lines.length; i < l; i ++ ) {

			const line = lines[ i ].trim();
			const split = line.split( /\s/g );

			switch ( split[ 0 ] ) {

				case 'TITLE':
					title = line.substring( 7, line.length - 1 );
					break;
				case 'LUT_3D_SIZE':
					// TODO: A .CUBE LUT file specifies floating point values and could be represented with
					// more precision than can be captured with Uint8Array.
					const sizeToken = split[ 1 ];
					size = parseFloat( sizeToken );
					data = new Uint8Array( size * size * size * 4 );
					break;
				case 'DOMAIN_MIN':
					domainMin.x = parseFloat( split[ 1 ] );
					domainMin.y = parseFloat( split[ 2 ] );
					domainMin.z = parseFloat( split[ 3 ] );
					break;
				case 'DOMAIN_MAX':
					domainMax.x = parseFloat( split[ 1 ] );
					domainMax.y = parseFloat( split[ 2 ] );
					domainMax.z = parseFloat( split[ 3 ] );
					break;
				default:
					const r = parseFloat( split[ 0 ] );
					const g = parseFloat( split[ 1 ] );
					const b = parseFloat( split[ 2 ] );

					if (
						r > 1.0 || r < 0.0 ||
						g > 1.0 || g < 0.0 ||
						b > 1.0 || b < 0.0
					) {

						throw new Error( 'LUTCubeLoader : Non normalized values not supported.' );

					}

					data[ currIndex + 0 ] = r * 255;
					data[ currIndex + 1 ] = g * 255;
					data[ currIndex + 2 ] = b * 255;
					data[ currIndex + 3 ] = 255;
					currIndex += 4;

			}

		}

		const texture = new DataTexture();
		texture.image.data = data;
		texture.image.width = size;
		texture.image.height = size * size;
		texture.type = UnsignedByteType;
		texture.magFilter = LinearFilter;
		texture.minFilter = LinearFilter;
		texture.wrapS = ClampToEdgeWrapping;
		texture.wrapT = ClampToEdgeWrapping;
		texture.generateMipmaps = false;
		texture.needsUpdate = true;

		const texture3D = new Data3DTexture();
		texture3D.image.data = data;
		texture3D.image.width = size;
		texture3D.image.height = size;
		texture3D.image.depth = size;
		texture3D.type = UnsignedByteType;
		texture3D.magFilter = LinearFilter;
		texture3D.minFilter = LinearFilter;
		texture3D.wrapS = ClampToEdgeWrapping;
		texture3D.wrapT = ClampToEdgeWrapping;
		texture3D.wrapR = ClampToEdgeWrapping;
		texture3D.generateMipmaps = false;
		texture3D.needsUpdate = true;

		return {
			title,
			size,
			domainMin,
			domainMax,
			texture,
			texture3D,
		};

	}

}