isosurface { //-------------------------------------------

  function{ 
    (f_checker(x*1.2,y*1.19,z*1.2)*0.08)
  }
  threshold 0.05
  contained_by {box {<-2,-3,-2>,<2,3.0,2>}}
  max_gradient 200
           
  texture{ pigment{ color rgb<1,1,1>*1.2 }
           //normal { bumps 0.5 scale 0.05}
           finish { specular 0.4 
                    phong 1 reflection 0.1}
	 }
  scale <0.5,0.25,0.5>*0.8
  rotate <0,-55,0>
  rotate <-30,0,0>  
  translate < 0, 1.4, -0.5>
} // end of isosurface -----------------------------------