text: /**
   * @author mrdoob / http://mrdoob.com
   * @author stewdio / http://stewd.io
   */
  
  THREE.ViveController = function ( id ) {
  
  	THREE.Object3D.call( this );
  
  	var scope = this;
  	var gamepad;
  
  	var axes = [ 0, 0 ];
  	var thumbpadIsPressed = false;
  	var triggerIsPressed = false;
  	var gripsArePressed = false;
  	var menuIsPressed = false;
  
  	function findGamepad( id ) {
  
  		// Iterate across gamepads as Vive Controllers may not be
  		// in position 0 and 1.
  
  		var gamepads = navigator.getGamepads();
  
  		for ( var i = 0, j = 0; i < 4; i ++ ) {
  
  			var gamepad = gamepads[ i ];
  
  			if ( gamepad && gamepad.id === 'OpenVR Gamepad' ) {
  
  				if ( j === id ) return gamepad;
  
  				j ++;
  
  			}
  
  		}
  
  	}
  
  	this.matrixAutoUpdate = false;
  	this.standingMatrix = new THREE.Matrix4();
  
  	this.getGamepad = function () {
  
  		return gamepad;
  
  	};
  
  	this.getButtonState = function ( button ) {
  
  		if ( button === 'thumbpad' ) return thumbpadIsPressed;
  		if ( button === 'trigger' ) return triggerIsPressed;
  		if ( button === 'grips' ) return gripsArePressed;
  		if ( button === 'menu' ) return menuIsPressed;
  
  	};
  
  	this.update = function () {
  
  		gamepad = findGamepad( id );
  
  		if ( gamepad !== undefined && gamepad.pose !== null ) {
  
  			//  Position and orientation.
  
  			var pose = gamepad.pose;
  
  			if ( pose.position !== null ) scope.position.fromArray( pose.position );
  			if ( pose.orientation !== null ) scope.quaternion.fromArray( pose.orientation );
  			scope.matrix.compose( scope.position, scope.quaternion, scope.scale );
  			scope.matrix.multiplyMatrices( scope.standingMatrix, scope.matrix );
  			scope.matrixWorldNeedsUpdate = true;
  			scope.visible = true;
  
  			//  Thumbpad and Buttons.
  
  			if ( axes[ 0 ] !== gamepad.axes[ 0 ] || axes[ 1 ] !== gamepad.axes[ 1 ] ) {
  
  				axes[ 0 ] = gamepad.axes[ 0 ]; //  X axis: -1 = Left, +1 = Right.
  				axes[ 1 ] = gamepad.axes[ 1 ]; //  Y axis: -1 = Bottom, +1 = Top.
  				scope.dispatchEvent( { type: 'axischanged', axes: axes } );
  
  			}
  
  			if ( thumbpadIsPressed !== gamepad.buttons[ 0 ].pressed ) {
  
  				thumbpadIsPressed = gamepad.buttons[ 0 ].pressed;
  				scope.dispatchEvent( { type: thumbpadIsPressed ? 'thumbpaddown' : 'thumbpadup' } );
  
  			}
  
  			if ( triggerIsPressed !== gamepad.buttons[ 1 ].pressed ) {
  
  				triggerIsPressed = gamepad.buttons[ 1 ].pressed;
  				scope.dispatchEvent( { type: triggerIsPressed ? 'triggerdown' : 'triggerup' } );
  
  			}
  
  			if ( gripsArePressed !== gamepad.buttons[ 2 ].pressed ) {
  
  				gripsArePressed = gamepad.buttons[ 2 ].pressed;
  				scope.dispatchEvent( { type: gripsArePressed ? 'gripsdown' : 'gripsup' } );
  
  			}
  
  			if ( menuIsPressed !== gamepad.buttons[ 3 ].pressed ) {
  
  				menuIsPressed = gamepad.buttons[ 3 ].pressed;
  				scope.dispatchEvent( { type: menuIsPressed ? 'menudown' : 'menuup' } );
  
  			}
  
  		} else {
  
  			scope.visible = false;
  
  		}
  
  	};
  
  };
  
  THREE.ViveController.prototype = Object.create( THREE.Object3D.prototype );
  THREE.ViveController.prototype.constructor = THREE.ViveController;
  