threejs/examples/js/loaders/LUT3dlLoader.js

( function () {

	// http://download.autodesk.com/us/systemdocs/help/2011/lustre/index.html?url=./files/WSc4e151a45a3b785a24c3d9a411df9298473-7ffd.htm,topicNumber=d0e9492
	class LUT3dlLoader extends THREE.Loader {

		load( url, onLoad, onProgress, onError ) {

			const loader = new THREE.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 comment lints
			str = str.replace( /^#.*?(\n|\r)/gm, '' ).replace( /^\s*?(\n|\r)/gm, '' ).trim();
			const lines = str.split( /[\n\r]+/g );

			// first line is the positions on the grid that are provided by the LUT
			const gridLines = lines[ 0 ].trim().split( /\s+/g ).map( e => parseFloat( e ) );
			const gridStep = gridLines[ 1 ] - gridLines[ 0 ];
			const size = gridLines.length;
			for ( let i = 1, l = gridLines.length; i < l; i ++ ) {

				if ( gridStep !== gridLines[ i ] - gridLines[ i - 1 ] ) {

					throw new Error( 'LUT3dlLoader: Inconsistent grid size not supported.' );

				}

			}

			const dataArray = new Array( size * size * size * 4 );
			let index = 0;
			let maxOutputValue = 0.0;
			for ( let i = 1, l = lines.length; i < l; i ++ ) {

				const line = lines[ i ].trim();
				const split = line.split( /\s/g );
				const r = parseFloat( split[ 0 ] );
				const g = parseFloat( split[ 1 ] );
				const b = parseFloat( split[ 2 ] );
				maxOutputValue = Math.max( maxOutputValue, r, g, b );
				const bLayer = index % size;
				const gLayer = Math.floor( index / size ) % size;
				const rLayer = Math.floor( index / ( size * size ) ) % size;

				// b grows first, then g, then r
				const pixelIndex = bLayer * size * size + gLayer * size + rLayer;
				dataArray[ 4 * pixelIndex + 0 ] = r;
				dataArray[ 4 * pixelIndex + 1 ] = g;
				dataArray[ 4 * pixelIndex + 2 ] = b;
				dataArray[ 4 * pixelIndex + 3 ] = 1.0;
				index += 1;

			}

			// Find the apparent bit depth of the stored RGB values and map the
			// values to [ 0, 255 ].
			const bits = Math.ceil( Math.log2( maxOutputValue ) );
			const maxBitValue = Math.pow( 2.0, bits );
			for ( let i = 0, l = dataArray.length; i < l; i += 4 ) {

				const r = dataArray[ i + 0 ];
				const g = dataArray[ i + 1 ];
				const b = dataArray[ i + 2 ];
				dataArray[ i + 0 ] = 255 * r / maxBitValue; // r
				dataArray[ i + 1 ] = 255 * g / maxBitValue; // g
				dataArray[ i + 2 ] = 255 * b / maxBitValue; // b

			}

			const data = new Uint8Array( dataArray );
			const texture = new THREE.DataTexture();
			texture.image.data = data;
			texture.image.width = size;
			texture.image.height = size * size;
			texture.format = THREE.RGBAFormat;
			texture.type = THREE.UnsignedByteType;
			texture.magFilter = THREE.LinearFilter;
			texture.minFilter = THREE.LinearFilter;
			texture.wrapS = THREE.ClampToEdgeWrapping;
			texture.wrapT = THREE.ClampToEdgeWrapping;
			texture.generateMipmaps = false;
			texture.needsUpdate = true;
			const texture3D = new THREE.Data3DTexture();
			texture3D.image.data = data;
			texture3D.image.width = size;
			texture3D.image.height = size;
			texture3D.image.depth = size;
			texture3D.format = THREE.RGBAFormat;
			texture3D.type = THREE.UnsignedByteType;
			texture3D.magFilter = THREE.LinearFilter;
			texture3D.minFilter = THREE.LinearFilter;
			texture3D.wrapS = THREE.ClampToEdgeWrapping;
			texture3D.wrapT = THREE.ClampToEdgeWrapping;
			texture3D.wrapR = THREE.ClampToEdgeWrapping;
			texture3D.generateMipmaps = false;
			texture3D.needsUpdate = true;
			return {
				size,
				texture,
				texture3D
			};

		}

	}

	THREE.LUT3dlLoader = LUT3dlLoader;

} )();