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

  function{ f_torus2( x,y,z, -0.75, 0.65, 0.02) // needs negative Field Strength 
                                                // or a negated function, major radius, minor radius
          }          

  contained_by {box {<-1,-1,-1>*1,<1,1,1>*1}}
  threshold 0.16 
  max_gradient 5
 
  texture{ pigment{ color rgb <1.0,0.05,0.20>} 
           normal { bumps 0.5 scale 0.035}
           finish { specular 0.2 phong 0.7 reflection 0.05}
         }
  rotate<-40,20,0>
  scale 1.5
  translate< 0,1.1,0>
} // end of isosurface -------------------------------------------------------