// 3D curved surface created from a mesh of triangles
bicubic_patch
{
  type 1 // patch_type (0..4)
  // 0 = Bezier patch, just store the triangular vertices
  // 1 = Bezier patch, store all plane equations defined by
  //       the triangulation of the patch into sub patches
  // 2 = Bezier patch, use binary subdivision to find the
  //       point of surface intersection.
  // 3 = Bezier patch, use binary subdivision & pre compute
  //       and store all vertices
  // 4 = Bezier patch, vertices, all plane equations, normals
  //       at each vertex of a subpatch are stored (to be used
  //       for a smooth triangle shading in each of subpatch).
  flatness 0.1 // flatness value (valid for type 2 or 3 only, remove for 0,1,4?)
  //       flatness_value = 0.01 to 1.0, with higher values
  //        giving flatter, less smooth results
  u_steps 3 // # of triangles to subdivide (1-5)
  v_steps 3 // # of triangles to subdivide (1-5)
  <0, 0, 2> <1, 0, 0> <2, 0, 0> <3, 0, -2>
  <0, 1, 0> <1, 1, 0> <2, 1, 0> <3, 1,  0>
  <0, 2, 0> <1, 2, 0> <2, 2, 0> <3, 2,  0>
  <0, 3, 2> <1, 3, 0> <2, 3, 0> <3, 3, -2>
}