text: import {
  	BufferAttribute,
  	BufferGeometry,
  	Float32BufferAttribute,
  	InterleavedBuffer,
  	InterleavedBufferAttribute,
  	TriangleFanDrawMode,
  	TriangleStripDrawMode,
  	TrianglesDrawMode,
  	Vector3
  } from 'three';
  
  
  function computeTangents( geometry ) {
  
  	geometry.computeTangents();
  	console.warn( 'THREE.BufferGeometryUtils: .computeTangents() has been removed. Use BufferGeometry.computeTangents() instead.' );
  
  }
  
  /**
  	 * @param  {Array<BufferGeometry>} geometries
  	 * @param  {Boolean} useGroups
  	 * @return {BufferGeometry}
  	 */
  function mergeBufferGeometries( geometries, useGroups = false ) {
  
  	const isIndexed = geometries[ 0 ].index !== null;
  
  	const attributesUsed = new Set( Object.keys( geometries[ 0 ].attributes ) );
  	const morphAttributesUsed = new Set( Object.keys( geometries[ 0 ].morphAttributes ) );
  
  	const attributes = {};
  	const morphAttributes = {};
  
  	const morphTargetsRelative = geometries[ 0 ].morphTargetsRelative;
  
  	const mergedGeometry = new BufferGeometry();
  
  	let offset = 0;
  
  	for ( let i = 0; i < geometries.length; ++ i ) {
  
  		const geometry = geometries[ i ];
  		let attributesCount = 0;
  
  		// ensure that all geometries are indexed, or none
  
  		if ( isIndexed !== ( geometry.index !== null ) ) {
  
  			console.error( 'THREE.BufferGeometryUtils: .mergeBufferGeometries() failed with geometry at index ' + i + '. All geometries must have compatible attributes; make sure index attribute exists among all geometries, or in none of them.' );
  			return null;
  
  		}
  
  		// gather attributes, exit early if they're different
  
  		for ( const name in geometry.attributes ) {
  
  			if ( ! attributesUsed.has( name ) ) {
  
  				console.error( 'THREE.BufferGeometryUtils: .mergeBufferGeometries() failed with geometry at index ' + i + '. All geometries must have compatible attributes; make sure "' + name + '" attribute exists among all geometries, or in none of them.' );
  				return null;
  
  			}
  
  			if ( attributes[ name ] === undefined ) attributes[ name ] = [];
  
  			attributes[ name ].push( geometry.attributes[ name ] );
  
  			attributesCount ++;
  
  		}
  
  		// ensure geometries have the same number of attributes
  
  		if ( attributesCount !== attributesUsed.size ) {
  
  			console.error( 'THREE.BufferGeometryUtils: .mergeBufferGeometries() failed with geometry at index ' + i + '. Make sure all geometries have the same number of attributes.' );
  			return null;
  
  		}
  
  		// gather morph attributes, exit early if they're different
  
  		if ( morphTargetsRelative !== geometry.morphTargetsRelative ) {
  
  			console.error( 'THREE.BufferGeometryUtils: .mergeBufferGeometries() failed with geometry at index ' + i + '. .morphTargetsRelative must be consistent throughout all geometries.' );
  			return null;
  
  		}
  
  		for ( const name in geometry.morphAttributes ) {
  
  			if ( ! morphAttributesUsed.has( name ) ) {
  
  				console.error( 'THREE.BufferGeometryUtils: .mergeBufferGeometries() failed with geometry at index ' + i + '.  .morphAttributes must be consistent throughout all geometries.' );
  				return null;
  
  			}
  
  			if ( morphAttributes[ name ] === undefined ) morphAttributes[ name ] = [];
  
  			morphAttributes[ name ].push( geometry.morphAttributes[ name ] );
  
  		}
  
  		// gather .userData
  
  		mergedGeometry.userData.mergedUserData = mergedGeometry.userData.mergedUserData || [];
  		mergedGeometry.userData.mergedUserData.push( geometry.userData );
  
  		if ( useGroups ) {
  
  			let count;
  
  			if ( isIndexed ) {
  
  				count = geometry.index.count;
  
  			} else if ( geometry.attributes.position !== undefined ) {
  
  				count = geometry.attributes.position.count;
  
  			} else {
  
  				console.error( 'THREE.BufferGeometryUtils: .mergeBufferGeometries() failed with geometry at index ' + i + '. The geometry must have either an index or a position attribute' );
  				return null;
  
  			}
  
  			mergedGeometry.addGroup( offset, count, i );
  
  			offset += count;
  
  		}
  
  	}
  
  	// merge indices
  
  	if ( isIndexed ) {
  
  		let indexOffset = 0;
  		const mergedIndex = [];
  
  		for ( let i = 0; i < geometries.length; ++ i ) {
  
  			const index = geometries[ i ].index;
  
  			for ( let j = 0; j < index.count; ++ j ) {
  
  				mergedIndex.push( index.getX( j ) + indexOffset );
  
  			}
  
  			indexOffset += geometries[ i ].attributes.position.count;
  
  		}
  
  		mergedGeometry.setIndex( mergedIndex );
  
  	}
  
  	// merge attributes
  
  	for ( const name in attributes ) {
  
  		const mergedAttribute = mergeBufferAttributes( attributes[ name ] );
  
  		if ( ! mergedAttribute ) {
  
  			console.error( 'THREE.BufferGeometryUtils: .mergeBufferGeometries() failed while trying to merge the ' + name + ' attribute.' );
  			return null;
  
  		}
  
  		mergedGeometry.setAttribute( name, mergedAttribute );
  
  	}
  
  	// merge morph attributes
  
  	for ( const name in morphAttributes ) {
  
  		const numMorphTargets = morphAttributes[ name ][ 0 ].length;
  
  		if ( numMorphTargets === 0 ) break;
  
  		mergedGeometry.morphAttributes = mergedGeometry.morphAttributes || {};
  		mergedGeometry.morphAttributes[ name ] = [];
  
  		for ( let i = 0; i < numMorphTargets; ++ i ) {
  
  			const morphAttributesToMerge = [];
  
  			for ( let j = 0; j < morphAttributes[ name ].length; ++ j ) {
  
  				morphAttributesToMerge.push( morphAttributes[ name ][ j ][ i ] );
  
  			}
  
  			const mergedMorphAttribute = mergeBufferAttributes( morphAttributesToMerge );
  
  			if ( ! mergedMorphAttribute ) {
  
  				console.error( 'THREE.BufferGeometryUtils: .mergeBufferGeometries() failed while trying to merge the ' + name + ' morphAttribute.' );
  				return null;
  
  			}
  
  			mergedGeometry.morphAttributes[ name ].push( mergedMorphAttribute );
  
  		}
  
  	}
  
  	return mergedGeometry;
  
  }
  
  /**
   * @param {Array<BufferAttribute>} attributes
   * @return {BufferAttribute}
   */
  function mergeBufferAttributes( attributes ) {
  
  	let TypedArray;
  	let itemSize;
  	let normalized;
  	let arrayLength = 0;
  
  	for ( let i = 0; i < attributes.length; ++ i ) {
  
  		const attribute = attributes[ i ];
  
  		if ( attribute.isInterleavedBufferAttribute ) {
  
  			console.error( 'THREE.BufferGeometryUtils: .mergeBufferAttributes() failed. InterleavedBufferAttributes are not supported.' );
  			return null;
  
  		}
  
  		if ( TypedArray === undefined ) TypedArray = attribute.array.constructor;
  		if ( TypedArray !== attribute.array.constructor ) {
  
  			console.error( 'THREE.BufferGeometryUtils: .mergeBufferAttributes() failed. BufferAttribute.array must be of consistent array types across matching attributes.' );
  			return null;
  
  		}
  
  		if ( itemSize === undefined ) itemSize = attribute.itemSize;
  		if ( itemSize !== attribute.itemSize ) {
  
  			console.error( 'THREE.BufferGeometryUtils: .mergeBufferAttributes() failed. BufferAttribute.itemSize must be consistent across matching attributes.' );
  			return null;
  
  		}
  
  		if ( normalized === undefined ) normalized = attribute.normalized;
  		if ( normalized !== attribute.normalized ) {
  
  			console.error( 'THREE.BufferGeometryUtils: .mergeBufferAttributes() failed. BufferAttribute.normalized must be consistent across matching attributes.' );
  			return null;
  
  		}
  
  		arrayLength += attribute.array.length;
  
  	}
  
  	const array = new TypedArray( arrayLength );
  	let offset = 0;
  
  	for ( let i = 0; i < attributes.length; ++ i ) {
  
  		array.set( attributes[ i ].array, offset );
  
  		offset += attributes[ i ].array.length;
  
  	}
  
  	return new BufferAttribute( array, itemSize, normalized );
  
  }
  
  /**
   * @param {Array<BufferAttribute>} attributes
   * @return {Array<InterleavedBufferAttribute>}
   */
  function interleaveAttributes( attributes ) {
  
  	// Interleaves the provided attributes into an InterleavedBuffer and returns
  	// a set of InterleavedBufferAttributes for each attribute
  	let TypedArray;
  	let arrayLength = 0;
  	let stride = 0;
  
  	// calculate the the length and type of the interleavedBuffer
  	for ( let i = 0, l = attributes.length; i < l; ++ i ) {
  
  		const attribute = attributes[ i ];
  
  		if ( TypedArray === undefined ) TypedArray = attribute.array.constructor;
  		if ( TypedArray !== attribute.array.constructor ) {
  
  			console.error( 'AttributeBuffers of different types cannot be interleaved' );
  			return null;
  
  		}
  
  		arrayLength += attribute.array.length;
  		stride += attribute.itemSize;
  
  	}
  
  	// Create the set of buffer attributes
  	const interleavedBuffer = new InterleavedBuffer( new TypedArray( arrayLength ), stride );
  	let offset = 0;
  	const res = [];
  	const getters = [ 'getX', 'getY', 'getZ', 'getW' ];
  	const setters = [ 'setX', 'setY', 'setZ', 'setW' ];
  
  	for ( let j = 0, l = attributes.length; j < l; j ++ ) {
  
  		const attribute = attributes[ j ];
  		const itemSize = attribute.itemSize;
  		const count = attribute.count;
  		const iba = new InterleavedBufferAttribute( interleavedBuffer, itemSize, offset, attribute.normalized );
  		res.push( iba );
  
  		offset += itemSize;
  
  		// Move the data for each attribute into the new interleavedBuffer
  		// at the appropriate offset
  		for ( let c = 0; c < count; c ++ ) {
  
  			for ( let k = 0; k < itemSize; k ++ ) {
  
  				iba[ setters[ k ] ]( c, attribute[ getters[ k ] ]( c ) );
  
  			}
  
  		}
  
  	}
  
  	return res;
  
  }
  
  /**
   * @param {Array<BufferGeometry>} geometry
   * @return {number}
   */
  function estimateBytesUsed( geometry ) {
  
  	// Return the estimated memory used by this geometry in bytes
  	// Calculate using itemSize, count, and BYTES_PER_ELEMENT to account
  	// for InterleavedBufferAttributes.
  	let mem = 0;
  	for ( const name in geometry.attributes ) {
  
  		const attr = geometry.getAttribute( name );
  		mem += attr.count * attr.itemSize * attr.array.BYTES_PER_ELEMENT;
  
  	}
  
  	const indices = geometry.getIndex();
  	mem += indices ? indices.count * indices.itemSize * indices.array.BYTES_PER_ELEMENT : 0;
  	return mem;
  
  }
  
  /**
   * @param {BufferGeometry} geometry
   * @param {number} tolerance
   * @return {BufferGeometry>}
   */
  function mergeVertices( geometry, tolerance = 1e-4 ) {
  
  	tolerance = Math.max( tolerance, Number.EPSILON );
  
  	// Generate an index buffer if the geometry doesn't have one, or optimize it
  	// if it's already available.
  	const hashToIndex = {};
  	const indices = geometry.getIndex();
  	const positions = geometry.getAttribute( 'position' );
  	const vertexCount = indices ? indices.count : positions.count;
  
  	// next value for triangle indices
  	let nextIndex = 0;
  
  	// attributes and new attribute arrays
  	const attributeNames = Object.keys( geometry.attributes );
  	const attrArrays = {};
  	const morphAttrsArrays = {};
  	const newIndices = [];
  	const getters = [ 'getX', 'getY', 'getZ', 'getW' ];
  
  	// initialize the arrays
  	for ( let i = 0, l = attributeNames.length; i < l; i ++ ) {
  
  		const name = attributeNames[ i ];
  
  		attrArrays[ name ] = [];
  
  		const morphAttr = geometry.morphAttributes[ name ];
  		if ( morphAttr ) {
  
  			morphAttrsArrays[ name ] = new Array( morphAttr.length ).fill().map( () => [] );
  
  		}
  
  	}
  
  	// convert the error tolerance to an amount of decimal places to truncate to
  	const decimalShift = Math.log10( 1 / tolerance );
  	const shiftMultiplier = Math.pow( 10, decimalShift );
  	for ( let i = 0; i < vertexCount; i ++ ) {
  
  		const index = indices ? indices.getX( i ) : i;
  
  		// Generate a hash for the vertex attributes at the current index 'i'
  		let hash = '';
  		for ( let j = 0, l = attributeNames.length; j < l; j ++ ) {
  
  			const name = attributeNames[ j ];
  			const attribute = geometry.getAttribute( name );
  			const itemSize = attribute.itemSize;
  
  			for ( let k = 0; k < itemSize; k ++ ) {
  
  				// double tilde truncates the decimal value
  				hash += `${ ~ ~ ( attribute[ getters[ k ] ]( index ) * shiftMultiplier ) },`;
  
  			}
  
  		}
  
  		// Add another reference to the vertex if it's already
  		// used by another index
  		if ( hash in hashToIndex ) {
  
  			newIndices.push( hashToIndex[ hash ] );
  
  		} else {
  
  			// copy data to the new index in the attribute arrays
  			for ( let j = 0, l = attributeNames.length; j < l; j ++ ) {
  
  				const name = attributeNames[ j ];
  				const attribute = geometry.getAttribute( name );
  				const morphAttr = geometry.morphAttributes[ name ];
  				const itemSize = attribute.itemSize;
  				const newarray = attrArrays[ name ];
  				const newMorphArrays = morphAttrsArrays[ name ];
  
  				for ( let k = 0; k < itemSize; k ++ ) {
  
  					const getterFunc = getters[ k ];
  					newarray.push( attribute[ getterFunc ]( index ) );
  
  					if ( morphAttr ) {
  
  						for ( let m = 0, ml = morphAttr.length; m < ml; m ++ ) {
  
  							newMorphArrays[ m ].push( morphAttr[ m ][ getterFunc ]( index ) );
  
  						}
  
  					}
  
  				}
  
  			}
  
  			hashToIndex[ hash ] = nextIndex;
  			newIndices.push( nextIndex );
  			nextIndex ++;
  
  		}
  
  	}
  
  	// Generate typed arrays from new attribute arrays and update
  	// the attributeBuffers
  	const result = geometry.clone();
  	for ( let i = 0, l = attributeNames.length; i < l; i ++ ) {
  
  		const name = attributeNames[ i ];
  		const oldAttribute = geometry.getAttribute( name );
  
  		const buffer = new oldAttribute.array.constructor( attrArrays[ name ] );
  		const attribute = new BufferAttribute( buffer, oldAttribute.itemSize, oldAttribute.normalized );
  
  		result.setAttribute( name, attribute );
  
  		// Update the attribute arrays
  		if ( name in morphAttrsArrays ) {
  
  			for ( let j = 0; j < morphAttrsArrays[ name ].length; j ++ ) {
  
  				const oldMorphAttribute = geometry.morphAttributes[ name ][ j ];
  
  				const buffer = new oldMorphAttribute.array.constructor( morphAttrsArrays[ name ][ j ] );
  				const morphAttribute = new BufferAttribute( buffer, oldMorphAttribute.itemSize, oldMorphAttribute.normalized );
  				result.morphAttributes[ name ][ j ] = morphAttribute;
  
  			}
  
  		}
  
  	}
  
  	// indices
  
  	result.setIndex( newIndices );
  
  	return result;
  
  }
  
  /**
   * @param {BufferGeometry} geometry
   * @param {number} drawMode
   * @return {BufferGeometry>}
   */
  function toTrianglesDrawMode( geometry, drawMode ) {
  
  	if ( drawMode === TrianglesDrawMode ) {
  
  		console.warn( 'THREE.BufferGeometryUtils.toTrianglesDrawMode(): Geometry already defined as triangles.' );
  		return geometry;
  
  	}
  
  	if ( drawMode === TriangleFanDrawMode || drawMode === TriangleStripDrawMode ) {
  
  		let index = geometry.getIndex();
  
  		// generate index if not present
  
  		if ( index === null ) {
  
  			const indices = [];
  
  			const position = geometry.getAttribute( 'position' );
  
  			if ( position !== undefined ) {
  
  				for ( let i = 0; i < position.count; i ++ ) {
  
  					indices.push( i );
  
  				}
  
  				geometry.setIndex( indices );
  				index = geometry.getIndex();
  
  			} else {
  
  				console.error( 'THREE.BufferGeometryUtils.toTrianglesDrawMode(): Undefined position attribute. Processing not possible.' );
  				return geometry;
  
  			}
  
  		}
  
  		//
  
  		const numberOfTriangles = index.count - 2;
  		const newIndices = [];
  
  		if ( drawMode === TriangleFanDrawMode ) {
  
  			// gl.TRIANGLE_FAN
  
  			for ( let i = 1; i <= numberOfTriangles; i ++ ) {
  
  				newIndices.push( index.getX( 0 ) );
  				newIndices.push( index.getX( i ) );
  				newIndices.push( index.getX( i + 1 ) );
  
  			}
  
  		} else {
  
  			// gl.TRIANGLE_STRIP
  
  			for ( let i = 0; i < numberOfTriangles; i ++ ) {
  
  				if ( i % 2 === 0 ) {
  
  					newIndices.push( index.getX( i ) );
  					newIndices.push( index.getX( i + 1 ) );
  					newIndices.push( index.getX( i + 2 ) );
  
  				} else {
  
  					newIndices.push( index.getX( i + 2 ) );
  					newIndices.push( index.getX( i + 1 ) );
  					newIndices.push( index.getX( i ) );
  
  				}
  
  			}
  
  		}
  
  		if ( ( newIndices.length / 3 ) !== numberOfTriangles ) {
  
  			console.error( 'THREE.BufferGeometryUtils.toTrianglesDrawMode(): Unable to generate correct amount of triangles.' );
  
  		}
  
  		// build final geometry
  
  		const newGeometry = geometry.clone();
  		newGeometry.setIndex( newIndices );
  		newGeometry.clearGroups();
  
  		return newGeometry;
  
  	} else {
  
  		console.error( 'THREE.BufferGeometryUtils.toTrianglesDrawMode(): Unknown draw mode:', drawMode );
  		return geometry;
  
  	}
  
  }
  
  /**
   * Calculates the morphed attributes of a morphed/skinned BufferGeometry.
   * Helpful for Raytracing or Decals.
   * @param {Mesh | Line | Points} object An instance of Mesh, Line or Points.
   * @return {Object} An Object with original position/normal attributes and morphed ones.
   */
  function computeMorphedAttributes( object ) {
  
  	if ( object.geometry.isBufferGeometry !== true ) {
  
  		console.error( 'THREE.BufferGeometryUtils: Geometry is not of type BufferGeometry.' );
  		return null;
  
  	}
  
  	const _vA = new Vector3();
  	const _vB = new Vector3();
  	const _vC = new Vector3();
  
  	const _tempA = new Vector3();
  	const _tempB = new Vector3();
  	const _tempC = new Vector3();
  
  	const _morphA = new Vector3();
  	const _morphB = new Vector3();
  	const _morphC = new Vector3();
  
  	function _calculateMorphedAttributeData(
  		object,
  		material,
  		attribute,
  		morphAttribute,
  		morphTargetsRelative,
  		a,
  		b,
  		c,
  		modifiedAttributeArray
  	) {
  
  		_vA.fromBufferAttribute( attribute, a );
  		_vB.fromBufferAttribute( attribute, b );
  		_vC.fromBufferAttribute( attribute, c );
  
  		const morphInfluences = object.morphTargetInfluences;
  
  		if ( material.morphTargets && morphAttribute && morphInfluences ) {
  
  			_morphA.set( 0, 0, 0 );
  			_morphB.set( 0, 0, 0 );
  			_morphC.set( 0, 0, 0 );
  
  			for ( let i = 0, il = morphAttribute.length; i < il; i ++ ) {
  
  				const influence = morphInfluences[ i ];
  				const morph = morphAttribute[ i ];
  
  				if ( influence === 0 ) continue;
  
  				_tempA.fromBufferAttribute( morph, a );
  				_tempB.fromBufferAttribute( morph, b );
  				_tempC.fromBufferAttribute( morph, c );
  
  				if ( morphTargetsRelative ) {
  
  					_morphA.addScaledVector( _tempA, influence );
  					_morphB.addScaledVector( _tempB, influence );
  					_morphC.addScaledVector( _tempC, influence );
  
  				} else {
  
  					_morphA.addScaledVector( _tempA.sub( _vA ), influence );
  					_morphB.addScaledVector( _tempB.sub( _vB ), influence );
  					_morphC.addScaledVector( _tempC.sub( _vC ), influence );
  
  				}
  
  			}
  
  			_vA.add( _morphA );
  			_vB.add( _morphB );
  			_vC.add( _morphC );
  
  		}
  
  		if ( object.isSkinnedMesh ) {
  
  			object.boneTransform( a, _vA );
  			object.boneTransform( b, _vB );
  			object.boneTransform( c, _vC );
  
  		}
  
  		modifiedAttributeArray[ a * 3 + 0 ] = _vA.x;
  		modifiedAttributeArray[ a * 3 + 1 ] = _vA.y;
  		modifiedAttributeArray[ a * 3 + 2 ] = _vA.z;
  		modifiedAttributeArray[ b * 3 + 0 ] = _vB.x;
  		modifiedAttributeArray[ b * 3 + 1 ] = _vB.y;
  		modifiedAttributeArray[ b * 3 + 2 ] = _vB.z;
  		modifiedAttributeArray[ c * 3 + 0 ] = _vC.x;
  		modifiedAttributeArray[ c * 3 + 1 ] = _vC.y;
  		modifiedAttributeArray[ c * 3 + 2 ] = _vC.z;
  
  	}
  
  	const geometry = object.geometry;
  	const material = object.material;
  
  	let a, b, c;
  	const index = geometry.index;
  	const positionAttribute = geometry.attributes.position;
  	const morphPosition = geometry.morphAttributes.position;
  	const morphTargetsRelative = geometry.morphTargetsRelative;
  	const normalAttribute = geometry.attributes.normal;
  	const morphNormal = geometry.morphAttributes.position;
  
  	const groups = geometry.groups;
  	const drawRange = geometry.drawRange;
  	let i, j, il, jl;
  	let group, groupMaterial;
  	let start, end;
  
  	const modifiedPosition = new Float32Array( positionAttribute.count * positionAttribute.itemSize );
  	const modifiedNormal = new Float32Array( normalAttribute.count * normalAttribute.itemSize );
  
  	if ( index !== null ) {
  
  		// indexed buffer geometry
  
  		if ( Array.isArray( material ) ) {
  
  			for ( i = 0, il = groups.length; i < il; i ++ ) {
  
  				group = groups[ i ];
  				groupMaterial = material[ group.materialIndex ];
  
  				start = Math.max( group.start, drawRange.start );
  				end = Math.min( ( group.start + group.count ), ( drawRange.start + drawRange.count ) );
  
  				for ( j = start, jl = end; j < jl; j += 3 ) {
  
  					a = index.getX( j );
  					b = index.getX( j + 1 );
  					c = index.getX( j + 2 );
  
  					_calculateMorphedAttributeData(
  						object,
  						groupMaterial,
  						positionAttribute,
  						morphPosition,
  						morphTargetsRelative,
  						a, b, c,
  						modifiedPosition
  					);
  
  					_calculateMorphedAttributeData(
  						object,
  						groupMaterial,
  						normalAttribute,
  						morphNormal,
  						morphTargetsRelative,
  						a, b, c,
  						modifiedNormal
  					);
  
  				}
  
  			}
  
  		} else {
  
  			start = Math.max( 0, drawRange.start );
  			end = Math.min( index.count, ( drawRange.start + drawRange.count ) );
  
  			for ( i = start, il = end; i < il; i += 3 ) {
  
  				a = index.getX( i );
  				b = index.getX( i + 1 );
  				c = index.getX( i + 2 );
  
  				_calculateMorphedAttributeData(
  					object,
  					material,
  					positionAttribute,
  					morphPosition,
  					morphTargetsRelative,
  					a, b, c,
  					modifiedPosition
  				);
  
  				_calculateMorphedAttributeData(
  					object,
  					material,
  					normalAttribute,
  					morphNormal,
  					morphTargetsRelative,
  					a, b, c,
  					modifiedNormal
  				);
  
  			}
  
  		}
  
  	} else if ( positionAttribute !== undefined ) {
  
  		// non-indexed buffer geometry
  
  		if ( Array.isArray( material ) ) {
  
  			for ( i = 0, il = groups.length; i < il; i ++ ) {
  
  				group = groups[ i ];
  				groupMaterial = material[ group.materialIndex ];
  
  				start = Math.max( group.start, drawRange.start );
  				end = Math.min( ( group.start + group.count ), ( drawRange.start + drawRange.count ) );
  
  				for ( j = start, jl = end; j < jl; j += 3 ) {
  
  					a = j;
  					b = j + 1;
  					c = j + 2;
  
  					_calculateMorphedAttributeData(
  						object,
  						groupMaterial,
  						positionAttribute,
  						morphPosition,
  						morphTargetsRelative,
  						a, b, c,
  						modifiedPosition
  					);
  
  					_calculateMorphedAttributeData(
  						object,
  						groupMaterial,
  						normalAttribute,
  						morphNormal,
  						morphTargetsRelative,
  						a, b, c,
  						modifiedNormal
  					);
  
  				}
  
  			}
  
  		} else {
  
  			start = Math.max( 0, drawRange.start );
  			end = Math.min( positionAttribute.count, ( drawRange.start + drawRange.count ) );
  
  			for ( i = start, il = end; i < il; i += 3 ) {
  
  				a = i;
  				b = i + 1;
  				c = i + 2;
  
  				_calculateMorphedAttributeData(
  					object,
  					material,
  					positionAttribute,
  					morphPosition,
  					morphTargetsRelative,
  					a, b, c,
  					modifiedPosition
  				);
  
  				_calculateMorphedAttributeData(
  					object,
  					material,
  					normalAttribute,
  					morphNormal,
  					morphTargetsRelative,
  					a, b, c,
  					modifiedNormal
  				);
  
  			}
  
  		}
  
  	}
  
  	const morphedPositionAttribute = new Float32BufferAttribute( modifiedPosition, 3 );
  	const morphedNormalAttribute = new Float32BufferAttribute( modifiedNormal, 3 );
  
  	return {
  
  		positionAttribute: positionAttribute,
  		normalAttribute: normalAttribute,
  		morphedPositionAttribute: morphedPositionAttribute,
  		morphedNormalAttribute: morphedNormalAttribute
  
  	};
  
  }
  
  
  
  export {
  	computeTangents,
  	mergeBufferGeometries,
  	mergeBufferAttributes,
  	interleaveAttributes,
  	estimateBytesUsed,
  	mergeVertices,
  	toTrianglesDrawMode,
  	computeMorphedAttributes,
  };
  