<!-- NEW3 — TEST 3 · THE RIVER'S JOURNEY · part 103 -->
+ ) {

			const group = groups[ i ];
			geometry2.addGroup( group.start, group.count, group.materialIndex );

		}

		return geometry2;

	}

	/**
	 * Serializes the geometry into JSON.
	 *
	 * @return {Object} A JSON object representing the serialized geometry.
	 */
	toJSON() {

		const data = {
			metadata: {
				version: 4.7,
				type: 'BufferGeometry',
				generator: 'BufferGeometry.toJSON'
			}
		};

		// standard BufferGeometry serialization

		data.uuid = this.uuid;
		data.type = ( this.parameters !== undefined && this._transformed === true ) ? 'BufferGeometry' : this.type;
		data.name = this.name;
		if ( Object.keys( this.userData ).length > 0 ) data.userData = this.userData;

		if ( this.parameters !== undefined && this._transformed !== true ) {

			const parameters = this.parameters;

			for ( const key in parameters ) {

				if ( parameters[ key ] !== undefined ) data[ key ] = parameters[ key ];

			}

			return data;

		}

		// for simplicity the code assumes attributes are not shared across geometries, see #15811

		data.data = { attributes: {} };

		const index = this.index;

		if ( index !== null ) {

			data.data.index = {
				type: index.array.constructor.name,
				array: Array.prototype.slice.call( index.array )
			};

		}

		const attributes = this.attributes;

		for ( const key in attributes ) {

			const attribute = attributes[ key ];

			data.data.attributes[ key ] = attribute.toJSON( data.data );

		}

		const morphAttributes = {};
		let hasMorphAttributes = false;

		for ( const key in this.morphAttributes ) {

			const attributeArray = this.morphAttributes[ key ];

			const array = [];

			for ( let i = 0, il = attributeArray.length; i < il; i ++ ) {

				const attribute = attributeArray[ i ];

				array.push( attribute.toJSON( data.data ) );

			}

			if ( array.length > 0 ) {

				morphAttributes[ key ] = array;

				hasMorphAttributes = true;

			}

		}

		if ( hasMorphAttributes ) {

			data.data.morphAttributes = morphAttributes;
			data.data.morphTargetsRelative = this.morphTargetsRelative;

		}

		const groups = this.groups;

		if ( groups.length > 0 ) {

			data.data.groups = JSON.parse( JSON.stringify( groups ) );

		}

		const boundingSphere = this.boundingSphere;

		if ( boundingSphere !== null ) {

			data.data.boundingSphere = boundingSphere.toJSON();

		}

		return data;

	}

	/**
	 * Returns a new geometry with copied values from this instance.
	 *
	 * @return {BufferGeometry} A clone of this instance.
	 */
	clone() {

		return new this.constructor().copy( this );

	}

	/**
	 * Copies the values of the given geometry to this instance.
	 *
	 * @param {BufferGeometry} source - The geometry to copy.
	 * @return {BufferGeometry} A reference to this instance.
	 */
	copy( source ) {

		// reset

		this.index = null;
		this.attributes = {};
		this.morphAttributes = {};
		this.groups = [];
		this.boundingBox = null;
		this.boundingSphere = null;

		// used for storing cloned, shared data

		const data = {};

		// name

		this.name = source.name;

		// index

		const index = source.index;

		if ( index !== null ) {

			this.setIndex( index.clone() );

		}

		// attributes

		const attributes = source.attributes;

		for ( const name in attributes ) {

			const attribute = attributes[ name ];
			this.setAttribute( name, attribute.clone( data ) );

		}

		// morph attributes

		const morphAttributes = source.morphAttributes;

		for ( const name in morphAttributes ) {

			const array = [];
			const morphAttribute = morphAttributes[ name ]; // morphAttribute: array of Float32BufferAttributes

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

				array.push( morphAttribute[ i ].clone( data ) );

			}

			this.morphAttributes[ name ] = array;

		}

		this.morphTargetsRelative = source.morphTargetsRelative;

		// groups

		const groups = source.groups;

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

			const group = groups[ i ];
			this.addGroup( group.start, group.count, group.materialIndex );

		}

		// bounding box

		const boundingBox = source.boundingBox;

		if ( boundingBox !== null ) {

			this.boundingBox = boundingBox.clone();

		}

		// bounding sphere

		const boundingSphere = source.boundingSphere;

		if ( boundingSphere !== null ) {

			this.boundingSphere = boundingSphere.clone();

		}

		// draw range

		this.drawRange.start = source.drawRange.start;
		this.drawRange.count = source.drawRange.count;

		// user data

		this.userData = source.userData;

		// transformed flag

		this._transformed = source._transformed;

		return this;

	}

	/**
	 * Frees the GPU-related resources allocated by this instance. Call this
	 * method whenever this instance is no longer used in your app.
	 *
	 * @fires BufferGeometry#dispose
	 */
	dispose() {

		this.dispatchEvent( { type: 'dispose' } );

	}

}

/**
 * "Interleaved" means that multiple attributes, possibly of different types,
 * (e.g., position, normal,