<!-- NEW1 — TEST 1 · THE LIVING DISTRICT · part 31 -->
			break;

			case 'ZYX':
				this._x = s1 * c2 * c3 - c1 * s2 * s3;
				this._y = c1 * s2 * c3 + s1 * c2 * s3;
				this._z = c1 * c2 * s3 - s1 * s2 * c3;
				this._w = c1 * c2 * c3 + s1 * s2 * s3;
				break;

			case 'YZX':
				this._x = s1 * c2 * c3 + c1 * s2 * s3;
				this._y = c1 * s2 * c3 + s1 * c2 * s3;
				this._z = c1 * c2 * s3 - s1 * s2 * c3;
				this._w = c1 * c2 * c3 - s1 * s2 * s3;
				break;

			case 'XZY':
				this._x = s1 * c2 * c3 - c1 * s2 * s3;
				this._y = c1 * s2 * c3 - s1 * c2 * s3;
				this._z = c1 * c2 * s3 + s1 * s2 * c3;
				this._w = c1 * c2 * c3 + s1 * s2 * s3;
				break;

			default:
				warn( 'Quaternion: .setFromEuler() encountered an unknown order: ' + order );

		}

		if ( update === true ) this._onChangeCallback();

		return this;

	}

	/**
	 * Sets this quaternion from the given axis and angle.
	 *
	 * @param {Vector3} axis - The normalized axis.
	 * @param {number} angle - The angle in radians.
	 * @return {Quaternion} A reference to this quaternion.
	 */
	setFromAxisAngle( axis, angle ) {

		const halfAngle = angle / 2, s = Math.sin( halfAngle );

		this._x = axis.x * s;
		this._y = axis.y * s;
		this._z = axis.z * s;
		this._w = Math.cos( halfAngle );

		this._onChangeCallback();

		return this;

	}

	/**
	 * Sets this quaternion from the given rotation matrix.
	 *
	 * @param {Matrix4} m - A 4x4 matrix of which the upper 3x3 of matrix is a pure rotation matrix (i.e. unscaled).
	 * @return {Quaternion} A reference to this quaternion.
	 */
	setFromRotationMatrix( m ) {

		// assumes the upper 3x3 of m is a pure rotation matrix (i.e, unscaled)

		const te = m.elements,

			m11 = te[ 0 ], m12 = te[ 4 ], m13 = te[ 8 ],
			m21 = te[ 1 ], m22 = te[ 5 ], m23 = te[ 9 ],
			m31 = te[ 2 ], m32 = te[ 6 ], m33 = te[ 10 ],

			trace = m11 + m22 + m33;

		if ( trace > 0 ) {

			const s = 0.5 / Math.sqrt( trace + 1.0 );

			this._w = 0.25 / s;
			this._x = ( m32 - m23 ) * s;
			this._y = ( m13 - m31 ) * s;
			this._z = ( m21 - m12 ) * s;

		} else if ( m11 > m22 && m11 > m33 ) {

			const s = 2.0 * Math.sqrt( 1.0 + m11 - m22 - m33 );

			this._w = ( m32 - m23 ) / s;
			this._x = 0.25 * s;
			this._y = ( m12 + m21 ) / s;
			this._z = ( m13 + m31 ) / s;

		} else if ( m22 > m33 ) {

			const s = 2.0 * Math.sqrt( 1.0 + m22 - m11 - m33 );

			this._w = ( m13 - m31 ) / s;
			this._x = ( m12 + m21 ) / s;
			this._y = 0.25 * s;
			this._z = ( m23 + m32 ) / s;

		} else {

			const s = 2.0 * Math.sqrt( 1.0 + m33 - m11 - m22 );

			this._w = ( m21 - m12 ) / s;
			this._x = ( m13 + m31 ) / s;
			this._y = ( m23 + m32 ) / s;
			this._z = 0.25 * s;

		}

		this._onChangeCallback();

		return this;

	}

	/**
	 * Sets this quaternion to the rotation required to rotate the direction vector
	 * `vFrom` to the direction vector `vTo`.
	 *
	 * @param {Vector3} vFrom - The first (normalized) direction vector.
	 * @param {Vector3} vTo - The second (normalized) direction vector.
	 * @return {Quaternion} A reference to this quaternion.
	 */
	setFromUnitVectors( vFrom, vTo ) {

		// assumes direction vectors vFrom and vTo are normalized

		let r = vFrom.dot( vTo ) + 1;

		if ( r < 1e-8 ) { // the epsilon value has been discussed in #31286

			// vFrom and vTo point in opposite directions

			r = 0;

			if ( Math.abs( vFrom.x ) > Math.abs( vFrom.z ) ) {

				this._x = - vFrom.y;
				this._y = vFrom.x;
				this._z = 0;
				this._w = r;

			} else {

				this._x = 0;
				this._y = - vFrom.z;
				this._z = vFrom.y;
				this._w = r;

			}

		} else {

			// crossVectors( vFrom, vTo ); // inlined to avoid cyclic dependency on Vector3

			this._x = vFrom.y * vTo.z - vFrom.z * vTo.y;
			this._y = vFrom.z * vTo.x - vFrom.x * vTo.z;
			this._z = vFrom.x * vTo.y - vFrom.y * vTo.x;
			this._w = r;

		}

		return this.normalize();

	}

	/**
	 * Returns the angle between this quaternion and the given one in radians.
	 *
	 * @param {Quaternion} q - The quaternion to compute the angle with.
	 * @return {number} The angle in radians.
	 */
	angleTo( q ) {

		return 2 * Math.acos( Math.abs( clamp( this.dot( q ), -1, 1 ) ) );

	}

	/**
	 * Rotates this quaternion by a given angular step to the given quaternion.
	 * The method ensures that the final quaternion will not overshoot `q`.
	 *
	 * @param {Quaternion} q - The target quaternion.
	 * @param {number} step - The angular step in radians.
	 * @return {Quaternion} A reference to this quaternion.
	 */
	rotateTowards( q, step ) {

		const angle = this.angleTo( q );

		if ( angle === 0 ) return this;

		const t = Math.min( 1, step / angle );

		this.slerp( q, t );

		return this;

	}

	/**
	 * Sets this quaternion to the identity quaternion; that is, to the
	 * quaternion that represents "no rotation".
	 *
	 * @return {Quaternion} A reference to this quaternion.
	 */
	identity() {

		return this.set( 0, 0, 0, 1 );

	}

	/**
	 * Inverts this quaternion via {@link Quaternion#conjugate}. The
	 * quaternion is assumed to have