/* Fake a Flog.* namespace */
  if(typeof(Flog) == 'undefined') var Flog = {};
  if(typeof(Flog.RayTracer) == 'undefined') Flog.RayTracer = {};
  
  Flog.RayTracer.Material.Chessboard = Class.create();
  
  Flog.RayTracer.Material.Chessboard.prototype = Object.extend(
      new Flog.RayTracer.Material.BaseMaterial(), {   
          colorEven: null,
          colorOdd: null,
          density: 0.5,
          
          initialize : function(colorEven, colorOdd, reflection, transparency, gloss, density) {
              this.colorEven = colorEven;
              this.colorOdd = colorOdd;
              this.reflection = reflection;
              this.transparency = transparency;
              this.gloss = gloss;
              this.density = density;
              this.hasTexture = true;
          },
          
          getColor: function(u, v){
              var t = this.wrapUp(u * this.density) * this.wrapUp(v * this.density);
              
              if(t < 0.0)
                  return this.colorEven;
              else
                  return this.colorOdd;
          },
          
          toString : function () {
              return 'ChessMaterial [gloss=' + this.gloss + ', transparency=' + this.transparency + ', hasTexture=' + this.hasTexture +']';   
          }
      }
  );