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

  function{ f_rounded_box( x, y, z,
                           0.3, // radius of curvature
                           0.7,0.7,0.7)// scale<x,y,z>
            -(f_agate( x, y, z)*0.5)
            
          }
  threshold 0
  contained_by {box {<-1,-1,-1>*1.2,<1,1,1>*1.2}}
  max_gradient 3.2

  texture {
            pigment{ color rgb<0.85,0.65,0.55>*0.8}
            //normal {bumps 0.5 scale 0.05}
            finish { phong 0.3}
	  }
  scale 0.900
  rotate <0,-40,0>
  rotate <-30,0,0>  
  translate < 0, 1.3, 0>
} // end of isosurface ----------------------------------