/* Fake a Flog.* namespace */
  if(typeof(Flog) == 'undefined') var Flog = {};
  if(typeof(Flog.RayTracer) == 'undefined') Flog.RayTracer = {};
  
  Flog.RayTracer.Camera = Class.create();
  
  Flog.RayTracer.Camera.prototype = {
      position: null,
      lookAt: null,
      equator: null,
      up: null,
      screen: null,
  
      initialize : function(pos, lookAt, up) {
          this.position = pos;
          this.lookAt = lookAt;
          this.up = up;
          this.equator = lookAt.normalize().cross(this.up);
          this.screen = Flog.RayTracer.Vector.prototype.add(this.position, this.lookAt);
      },
      
      getRay: function(vx, vy){
          var pos = Flog.RayTracer.Vector.prototype.subtract(
              this.screen,
              Flog.RayTracer.Vector.prototype.subtract(
                  Flog.RayTracer.Vector.prototype.multiplyScalar(this.equator, vx),
                  Flog.RayTracer.Vector.prototype.multiplyScalar(this.up, vy)
              )
          );
          pos.y = pos.y * -1;
          var dir = Flog.RayTracer.Vector.prototype.subtract(
              pos,
              this.position
          );
      
          var ray = new Flog.RayTracer.Ray(pos, dir.normalize());
          
          return ray;
      },
      
      toString : function () {
          return 'Ray []';    
      }
  }