STLLoader.js

( function () {

	/**
 * Description: A THREE loader for STL ASCII files, as created by Solidworks and other CAD programs.
 *
 * Supports both binary and ASCII encoded files, with automatic detection of type.
 *
 * The loader returns a non-indexed buffer geometry.
 *
 * Limitations:
 *  Binary decoding supports "Magics" color format (http://en.wikipedia.org/wiki/STL_(file_format)#Color_in_binary_STL).
 *  There is perhaps some question as to how valid it is to always assume little-endian-ness.
 *  ASCII decoding assumes file is UTF-8.
 *
 * Usage:
 *  const loader = new STLLoader();
 *  loader.load( './models/stl/slotted_disk.stl', function ( geometry ) {
 *    scene.add( new THREE.Mesh( geometry ) );
 *  });
 *
 * For binary STLs geometry might contain colors for vertices. To use it:
 *  // use the same code to load STL as above
 *  if (geometry.hasColors) {
 *    material = new THREE.MeshPhongMaterial({ opacity: geometry.alpha, vertexColors: true });
 *  } else { .... }
 *  const mesh = new THREE.Mesh( geometry, material );
 *
 * For ASCII STLs containing multiple solids, each solid is assigned to a different group.
 * Groups can be used to assign a different color by defining an array of materials with the same length of
 * geometry.groups and passing it to the Mesh constructor:
 *
 * const mesh = new THREE.Mesh( geometry, material );
 *
 * For example:
 *
 *  const materials = [];
 *  const nGeometryGroups = geometry.groups.length;
 *
 *  const colorMap = ...; // Some logic to index colors.
 *
 *  for (let i = 0; i < nGeometryGroups; i++) {
 *
 *		const material = new THREE.MeshPhongMaterial({
 *			color: colorMap[i],
 *			wireframe: false
 *		});
 *
 *  }
 *
 *  materials.push(material);
 *  const mesh = new THREE.Mesh(geometry, materials);
 */

	class STLLoader extends THREE.Loader {

		constructor( manager ) {

			super( manager );

		}

		load( url, onLoad, onProgress, onError ) {

			const scope = this;
			const loader = new THREE.FileLoader( this.manager );
			loader.setPath( this.path );
			loader.setResponseType( 'arraybuffer' );
			loader.setRequestHeader( this.requestHeader );
			loader.setWithCredentials( this.withCredentials );
			loader.load( url, function ( text ) {

				try {

					onLoad( scope.parse( text ) );

				} catch ( e ) {

					if ( onError ) {

						onError( e );

					} else {

						console.error( e );

					}

					scope.manager.itemError( url );

				}

			}, onProgress, onError );

		}

		parse( data ) {

			function isBinary( data ) {

				const reader = new DataView( data );
				const face_size = 32 / 8 * 3 + 32 / 8 * 3 * 3 + 16 / 8;
				const n_faces = reader.getUint32( 80, true );
				const expect = 80 + 32 / 8 + n_faces * face_size;

				if ( expect === reader.byteLength ) {

					return true;

				} // An ASCII STL data must begin with 'solid ' as the first six bytes.
				// However, ASCII STLs lacking the SPACE after the 'd' are known to be
				// plentiful.  So, check the first 5 bytes for 'solid'.
				// Several encodings, such as UTF-8, precede the text with up to 5 bytes:
				// https://en.wikipedia.org/wiki/Byte_order_mark#Byte_order_marks_by_encoding
				// Search for "solid" to start anywhere after those prefixes.
				// US-ASCII ordinal values for 's', 'o', 'l', 'i', 'd'


				const solid = [ 115, 111, 108, 105, 100 ];

				for ( let off = 0; off < 5; off ++ ) {

					// If "solid" text is matched to the current offset, declare it to be an ASCII STL.
					if ( matchDataViewAt( solid, reader, off ) ) return false;

				} // Couldn't find "solid" text at the beginning; it is binary STL.


				return true;

			}

			function matchDataViewAt( query, reader, offset ) {

				// Check if each byte in query matches the corresponding byte from the current offset
				for ( let i = 0, il = query.length; i < il; i ++ ) {

					if ( query[ i ] !== reader.getUint8( offset + i ) ) return false;

				}

				return true;

			}

			function parseBinary( data ) {

				const reader = new DataView( data );
				const faces = reader.getUint32( 80, true );
				let r,
					g,
					b,
					hasColors = false,
					colors;
				let defaultR, defaultG, defaultB, alpha; // process STL header
				// check for default color in header ("COLOR=rgba" sequence).

				for ( let index = 0; index < 80 - 10; index ++ ) {

					if ( reader.getUint32( index, false ) == 0x434F4C4F
        /*COLO*/
        && reader.getUint8( index + 4 ) == 0x52
        /*'R'*/
        && reader.getUint8( index + 5 ) == 0x3D
        /*'='*/
					) {

						hasColors = true;
						colors = new Float32Array( faces * 3 * 3 );
						defaultR = reader.getUint8( index + 6 ) / 255;
						defaultG = reader.getUint8( index + 7 ) / 255;
						defaultB = reader.getUint8( index + 8 ) / 255;
						alpha = reader.getUint8( index + 9 ) / 255;

					}

				}

				const dataOffset = 84;
				const faceLength = 12 * 4 + 2;
				const geometry = new THREE.BufferGeometry();
				const vertices = new Float32Array( faces * 3 * 3 );
				const normals = new Float32Array( faces * 3 * 3 );

				for ( let face = 0; face < faces; face ++ ) {

					const start = dataOffset + face * faceLength;
					const normalX = reader.getFloat32( start, true );
					const normalY = reader.getFloat32( start + 4, true );
					const normalZ = reader.getFloat32( start + 8, true );

					if ( hasColors ) {

						const packedColor = reader.getUint16( start + 48, true );

						if ( ( packedColor & 0x8000 ) === 0 ) {

							// facet has its own unique color
							r = ( packedColor & 0x1F ) / 31;
							g = ( packedColor >> 5 & 0x1F ) / 31;
							b = ( packedColor >> 10 & 0x1F ) / 31;

						} else {

							r = defaultR;
							g = defaultG;
							b = defaultB;

						}

					}

					for ( let i = 1; i <= 3; i ++ ) {

						const vertexstart = start + i * 12;
						const componentIdx = face * 3 * 3 + ( i - 1 ) * 3;
						vertices[ componentIdx ] = reader.getFloat32( vertexstart, true );
						vertices[ componentIdx + 1 ] = reader.getFloat32( vertexstart + 4, true );
						vertices[ componentIdx + 2 ] = reader.getFloat32( vertexstart + 8, true );
						normals[ componentIdx ] = normalX;
						normals[ componentIdx + 1 ] = normalY;
						normals[ componentIdx + 2 ] = normalZ;

						if ( hasColors ) {

							colors[ componentIdx ] = r;
							colors[ componentIdx + 1 ] = g;
							colors[ componentIdx + 2 ] = b;

						}

					}

				}

				geometry.setAttribute( 'position', new THREE.BufferAttribute( vertices, 3 ) );
				geometry.setAttribute( 'normal', new THREE.BufferAttribute( normals, 3 ) );

				if ( hasColors ) {

					geometry.setAttribute( 'color', new THREE.BufferAttribute( colors, 3 ) );
					geometry.hasColors = true;
					geometry.alpha = alpha;

				}

				return geometry;

			}

			function parseASCII( data ) {

				const geometry = new THREE.BufferGeometry();
				const patternSolid = /solid([\s\S]*?)endsolid/g;
				const patternFace = /facet([\s\S]*?)endfacet/g;
				let faceCounter = 0;
				const patternFloat = /[\s]+([+-]?(?:\d*)(?:\.\d*)?(?:[eE][+-]?\d+)?)/.source;
				const patternVertex = new RegExp( 'vertex' + patternFloat + patternFloat + patternFloat, 'g' );
				const patternNormal = new RegExp( 'normal' + patternFloat + patternFloat + patternFloat, 'g' );
				const vertices = [];
				const normals = [];
				const normal = new THREE.Vector3();
				let result;
				let groupCount = 0;
				let startVertex = 0;
				let endVertex = 0;

				while ( ( result = patternSolid.exec( data ) ) !== null ) {

					startVertex = endVertex;
					const solid = result[ 0 ];

					while ( ( result = patternFace.exec( solid ) ) !== null ) {

						let vertexCountPerFace = 0;
						let normalCountPerFace = 0;
						const text = result[ 0 ];

						while ( ( result = patternNormal.exec( text ) ) !== null ) {

							normal.x = parseFloat( result[ 1 ] );
							normal.y = parseFloat( result[ 2 ] );
							normal.z = parseFloat( result[ 3 ] );
							normalCountPerFace ++;

						}

						while ( ( result = patternVertex.exec( text ) ) !== null ) {

							vertices.push( parseFloat( result[ 1 ] ), parseFloat( result[ 2 ] ), parseFloat( result[ 3 ] ) );
							normals.push( normal.x, normal.y, normal.z );
							vertexCountPerFace ++;
							endVertex ++;

						} // every face have to own ONE valid normal


						if ( normalCountPerFace !== 1 ) {

							console.error( 'THREE.STLLoader: Something isn\'t right with the normal of face number ' + faceCounter );

						} // each face have to own THREE valid vertices


						if ( vertexCountPerFace !== 3 ) {

							console.error( 'THREE.STLLoader: Something isn\'t right with the vertices of face number ' + faceCounter );

						}

						faceCounter ++;

					}

					const start = startVertex;
					const count = endVertex - startVertex;
					geometry.addGroup( start, count, groupCount );
					groupCount ++;

				}

				geometry.setAttribute( 'position', new THREE.Float32BufferAttribute( vertices, 3 ) );
				geometry.setAttribute( 'normal', new THREE.Float32BufferAttribute( normals, 3 ) );
				return geometry;

			}

			function ensureString( buffer ) {

				if ( typeof buffer !== 'string' ) {

					return THREE.LoaderUtils.decodeText( new Uint8Array( buffer ) );

				}

				return buffer;

			}

			function ensureBinary( buffer ) {

				if ( typeof buffer === 'string' ) {

					const array_buffer = new Uint8Array( buffer.length );

					for ( let i = 0; i < buffer.length; i ++ ) {

						array_buffer[ i ] = buffer.charCodeAt( i ) & 0xff; // implicitly assumes little-endian

					}

					return array_buffer.buffer || array_buffer;

				} else {

					return buffer;

				}

			} // start


			const binData = ensureBinary( data );
			return isBinary( binData ) ? parseBinary( binData ) : parseASCII( ensureString( data ) );

		}

	}

	THREE.STLLoader = STLLoader;

} )();