Gists/matrix_to_facedir.lua

-- Code by Pedro Gimeno, donated to the public domain.
-- Big thanks to entuland for making it much easier to create the table.

local facedirs = {
  [-246] = 19;
  [-244] = 10;
  [-242] = 4;
  [-240] = 13;
  [ -90] = 21;
  [ -82] = 20;
  [ -80] = 22;
  [ -72] = 23;
  [ -36] = 7;
  [ -30] = 18;
  [ -24] = 12;
  [ -18] = 9;
  [  18] = 11;
  [  24] = 16;
  [  30] = 14;
  [  36] = 5;
  [  72] = 3;
  [  80] = 2;
  [  82] = 0;
  [  90] = 1;
  [ 240] = 17;
  [ 242] = 6;
  [ 244] = 8;
  [ 246] = 15;
}

local function matrix_to_facedir(matrix)
  local index = matrix[1] +  3 * matrix[2] +   9 * matrix[3]
         + 27 * matrix[5] + 81 * matrix[6] + 243 * matrix[7]
  return facedirs[index] or 0
end

return matrix_to_facedir