#include "common.povinc"

#declare fx = 0.5;
#declare fy = 2.0;
#declare cf = 0.5;
#declare ts = 1.0;
#declare chx = 0.7;
#declare chy = -0.1;
#declare hts = 0.5;

#declare eps = 0.5;

#declare bean = function { sqrt(fx*x*x + fy*(y-cf*x*x)*(y-cf*x*x) + z*z) - ts }
#declare hole = function { sqrt((x - chx)*(x - chx) + (y - chy)*(y - chy) + z*z) - hts }
#declare smoo = function(d) { 0.5*tanh (d/eps) + 0.5 }

#declare grotto = 
isosurface {
  function { bean(x,y,z) - smoo(-bean(x,y,z)-hole(x,y,z))*(bean(x,y,z)+hole(x,y,z)) }
  open
  max_gradient 4
  contained_by { box { <-1.6,-1,-1.5>, <1.6,1.5,1.5> } }
  //scale <1, .25, 1>
  //rotate <30, 0, 45>
  rotate 70*y
  translate -0.25*y
}