// Very simple but highly effective dark cave entrance
// (c) auld 2006-
//  This is expanded by hand from the entry so may have bugs...

#macro 
  A(f) finish{
        reflection{,f}
       } 
#end

// The Cliff wall
union {
  plane { z, 20} 
  normal{ wrinkles }
  A(2)
}
// The Cave entrance...the trick here is how the sphere has an arch look
// Due to the reflections
union {
  sphere { z*22-3 , 5}
  A(1)
}
// The dark sea...trick to not use waves gives a rougher sea look with less bytes
// we displace the normal using agate.
union {
  plane { y, -3 }
  normal {
    agate 0.3
  }
  A(1)
}
sky_sphere {
  pigment {
    agate scale 3
  }
}