/**
 * @author alteredq / http://alteredqualia.com/
 *
 *	- shows frustum, line of sight and up of the camera
 *	- suitable for fast updates
 * 	- based on frustum visualization in lightgl.js shadowmap example
 *		http://evanw.github.com/lightgl.js/tests/shadowmap.html
 */

THREE.CameraHelper = function ( camera ) {

	var geometry = new THREE.Geometry();
	var material = new THREE.LineBasicMaterial( { color: 0xffffff, vertexColors: THREE.FaceColors } );

	var pointMap = {};

	// colors

	var hexFrustum = 0xffaa00;
	var hexCone = 0xff0000;
	var hexUp = 0x00aaff;
	var hexTarget = 0xffffff;
	var hexCross = 0x333333;

	// near

	addLine( "n1", "n2", hexFrustum );
	addLine( "n2", "n4", hexFrustum );
	addLine( "n4", "n3", hexFrustum );
	addLine( "n3", "n1", hexFrustum );

	// far

	addLine( "f1", "f2", hexFrustum );
	addLine( "f2", "f4", hexFrustum );
	addLine( "f4", "f3", hexFrustum );
	addLine( "f3", "f1", hexFrustum );

	// sides

	addLine( "n1", "f1", hexFrustum );
	addLine( "n2", "f2", hexFrustum );
	addLine( "n3", "f3", hexFrustum );
	addLine( "n4", "f4", hexFrustum );

	// cone

	addLine( "p", "n1", hexCone );
	addLine( "p", "n2", hexCone );
	addLine( "p", "n3", hexCone );
	addLine( "p", "n4", hexCone );

	// up

	addLine( "u1", "u2", hexUp );
	addLine( "u2", "u3", hexUp );
	addLine( "u3", "u1", hexUp );

	// target

	addLine( "c", "t", hexTarget );
	addLine( "p", "c", hexCross );

	// cross

	addLine( "cn1", "cn2", hexCross );
	addLine( "cn3", "cn4", hexCross );

	addLine( "cf1", "cf2", hexCross );
	addLine( "cf3", "cf4", hexCross );

	function addLine( a, b, hex ) {

		addPoint( a, hex );
		addPoint( b, hex );

	}

	function addPoint( id, hex ) {

		geometry.vertices.push( new THREE.Vector3() );
		geometry.colors.push( new THREE.Color( hex ) );

		if ( pointMap[ id ] === undefined ) {

			pointMap[ id ] = [];

		}

		pointMap[ id ].push( geometry.vertices.length - 1 );

	}

	THREE.Line.call( this, geometry, material, THREE.LinePieces );

	this.camera = camera;
	this.matrixWorld = camera.matrixWorld;
	this.matrixAutoUpdate = false;

	this.pointMap = pointMap;

	this.update();

};

THREE.CameraHelper.prototype = Object.create( THREE.Line.prototype );

THREE.CameraHelper.prototype.update = function () {

	var vector = new THREE.Vector3();
	var camera = new THREE.Camera();
	var projector = new THREE.Projector();

	return function () {

		var scope = this;

		var w = 1, h = 1;

		// we need just camera projection matrix
		// world matrix must be identity

		camera.projectionMatrix.copy( this.camera.projectionMatrix );

		// center / target

		setPoint( "c", 0, 0, - 1 );
		setPoint( "t", 0, 0,  1 );

		// near

		setPoint( "n1", - w, - h, - 1 );
		setPoint( "n2",  w, - h, - 1 );
		setPoint( "n3", - w,  h, - 1 );
		setPoint( "n4",  w,  h, - 1 );

		// far

		setPoint( "f1", - w, - h, 1 );
		setPoint( "f2",  w, - h, 1 );
		setPoint( "f3", - w,  h, 1 );
		setPoint( "f4",  w,  h, 1 );

		// up

		setPoint( "u1",  w * 0.7, h * 1.1, - 1 );
		setPoint( "u2", - w * 0.7, h * 1.1, - 1 );
		setPoint( "u3",        0, h * 2,   - 1 );

		// cross

		setPoint( "cf1", - w,  0, 1 );
		setPoint( "cf2",  w,  0, 1 );
		setPoint( "cf3",  0, - h, 1 );
		setPoint( "cf4",  0,  h, 1 );

		setPoint( "cn1", - w,  0, - 1 );
		setPoint( "cn2",  w,  0, - 1 );
		setPoint( "cn3",  0, - h, - 1 );
		setPoint( "cn4",  0,  h, - 1 );

		function setPoint( point, x, y, z ) {

			vector.set( x, y, z );
			projector.unprojectVector( vector, camera );

			var points = scope.pointMap[ point ];

			if ( points !== undefined ) {

				for ( var i = 0, il = points.length; i < il; i ++ ) {

					scope.geometry.vertices[ points[ i ] ].copy( vector );

				}

			}

		}

		this.geometry.verticesNeedUpdate = true;

	};

}();