// Some decorative elements
// Last edited on 2005-08-28 15:11:06 by stolfi

#macro treoid(pos, tree_height, tree_radius)
  #local bot = pos - 1.0*z;
  #local top = bot + (tree_height - 2*tree_radius + 0.01)*z;
  #local ctr = bot + (tree_height - tree_radius)*z;
  union {
    cylinder { bot, top, 0.10 texture { tx_trunk } }
    sphere { ctr, tree_radius texture { tx_leaves } }
  }
#end

#macro tree_ring(K, ring_radius, tree_height)
  #local tx_trunk =
    texture {
      pigment { color rgb < 0.500, 0.200, 0.000 > }
      finish { diffuse 0.8 ambient 0.2 }
    }
  #local tx_leaves =
    texture {
      pigment { color rgb < 0.400, 0.800, 0.000 > }
      finish { diffuse 0.8 ambient 0.2 }
    }

  #local sv = < ring_radius, 0, 0 >;
  #local gen = seed(4615);
  union {
    #local i = 0;
    #while(i < K)
      #local dx = 0.30*(2*rand(gen)-1);
      #local dy = 0.30*(2*rand(gen)-1);
      treoid(vrotate(sv, i*360/K*z) + < dx, dy, 0 >, 1.50, 0.50)
      #local i = i+1;
    #end
  }
#end