//---------------------------------------------------------------------------
#declare Pigment_1 = 
pigment{ spiral1 1  sine_wave
         color_map {[0, rgb 0.0]
                    [1, rgb 1 ]
                   }
          rotate<90,0,0>
          scale<1,0.30,1> 
        } // end of pigment  


#declare fn_Pigment_1 = 
function {pigment{ Pigment_1} }


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

  function{  sqrt(x*x*4 + z*z*4) 
             - abs(y) 

             + fn_Pigment_1(x,y,z).gray*0.15
          }
  threshold 0
  accuracy 0.0001
  max_gradient 5
  contained_by {box {<-1,-1,-1>, < 1,0, 1>}}
  //open
  texture { pigment{ color rgb<0.7,0.6,0.85>*0.9}
            finish { specular 0.1 roughness 0.005  phong 1 phong_size 20}
          }
  scale 1.0
  rotate <0,-90, 0>
  translate <-0, 1.0, 0>
} // end of isosurface -----------------------------------------------------