@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

class CameraHelper extends Line {

 static Projector __projector = new Projector();
 static Vector3 __v = new Vector3.zero();
 static Camera __c = new Camera(0.0 ,0.0);

 Camera camera;

 Matrix4 matrixWorld;
 bool matrixAutoUpdate;
 Map pointMap;

 CameraHelper( this.camera ) :
   matrixAutoUpdate = false,
   pointMap = {},
   super(
       new Geometry(),
       new LineBasicMaterial( color: 0xffffff, vertexColors: FaceColors ),
       LinePieces) {

   matrixWorld = camera.matrixWorld;
   // 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 );

   update();
 }

 addLine( a, b, hex ) {

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

 }

 addPoint( id, hex ) {

   geometry.vertices.add( new Vector3.zero() );
   geometry.colors.add( new Color( hex ) );

   if ( !pointMap.containsKey( id )) {
     pointMap[ id ] = [];
   }

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

 }

 setPoint( String point, double x, double y, double z ) {

   __v.setValues( x, y, z );
   __projector.unprojectVector( __v, __c );

   var points = pointMap[ point ];

   if ( points != null ) {

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

       geometry.vertices[ points[ i ] ].setFrom( __v );

     }

   }

 }
 update() {

   var w = 1.0, h = 1.0;

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

   __c.projectionMatrix.setFrom( camera.projectionMatrix );

   // center / target

   setPoint( "c", 0.0, 0.0, -1.0 );
   setPoint( "t", 0.0, 0.0,  1.0 );

   // near

   setPoint( "n1", -w, -h, -1.0 );
   setPoint( "n2",  w, -h, -1.0 );
   setPoint( "n3", -w,  h, -1.0 );
   setPoint( "n4",  w,  h, -1.0 );

   // far

   setPoint( "f1", -w, -h, 1.0 );
   setPoint( "f2",  w, -h, 1.0 );
   setPoint( "f3", -w,  h, 1.0 );
   setPoint( "f4",  w,  h, 1.0 );

   // up

   setPoint( "u1",  w * 0.7, h * 1.1, -1.0 );
   setPoint( "u2", -w * 0.7, h * 1.1, -1.0 );
   setPoint( "u3",      0.0, h * 2.0, -1.0 );

   // cross

   setPoint( "cf1", -w,  0.0, 1.0 );
   setPoint( "cf2",  w,  0.0, 1.0 );
   setPoint( "cf3",  0.0, -h, 1.0 );
   setPoint( "cf4",  0.0,  h, 1.0 );

   setPoint( "cn1", -w,  0.0, -1.0 );
   setPoint( "cn2",  w,  0.0, -1.0 );
   setPoint( "cn3",  0.0, -h, -1.0 );
   setPoint( "cn4",  0.0,  h, -1.0 );



   geometry["verticesNeedUpdate"] = true;

 }

}