// rounded tetrahedron macro include file
// Bill Pragnell 2006

#macro RoundedTetra(a, b)
  #local f_f = degrees(acos(tan(radians(30))*tan(radians(30))));
  #local f_e = (180-f_f)/2;
  #local r = a*sin(radians(f_f/2));
  #local rb = r + b;
  #local a2 = (r+b) / sin(radians(f_f/2));
  #local a_edge = a + b*cos(radians((180-f_f)/2));
  #local a_vert = 2*(sqrt(3*a*a) + b*cos(radians((180-f_e)/2)));
  union {
    sphere { <-a, a, a>, b }
    sphere { <a, a, -a>, b }
    sphere { <a, -a, a>, b }
    sphere { <-a, -a, -a>, b }
    cylinder { <-a, a, a>, <a, a, -a>, b }
    cylinder { <a, -a, a>, <-a, -a, -a>, b }
    cylinder { <a, a, -a>, <-a, -a, -a>, b }
    cylinder { <a, a, -a>, <a, -a, a>, b }
    cylinder { <-a, a, a>, <a, -a, a>, b }
    cylinder { <-a, a, a>, <-a, -a, -a>, b }
    intersection {
      // major faces
      plane { <1, 1, 1>, rb }
      plane { <-1, 1, -1>, rb }
      plane { <1, -1, -1>, rb }
      plane { <-1, -1, 1>, rb }
      // edge bevels
      plane { <0, 1, 0>, a_edge }
      plane { <0, -1, 0>, a_edge }
      plane { <-1, 0, 0>, a_edge }
      plane { <1, 0, 0>, a_edge }
      plane { <0, 0, 1>, a_edge }
      plane { <0, 0, -1>, a_edge }
      // vertex bevels
      plane { <-1, 1, 1>, a_vert }
      plane { <1, 1, -1>, a_vert }
      plane { <-1, -1, -1>, a_vert }
      plane { <1, -1, 1>, a_vert } }
    pigment { color White } }
#end