moveForward( distance ) {

		if ( this.enabled === false ) return;

		// move forward parallel to the xz-plane
		// assumes camera.up is y-up

		const camera = this.object;

		_vector.setFromMatrixColumn( camera.matrix, 0 );

		_vector.crossVectors( camera.up, _vector );

		camera.position.addScaledVector( _vector, distance );

	}
Moves the camera forward parallel to the xz-plane. Assumes camera.up is y-up.

@param {number} distance - The signed distance.