Reordering elements by xi

In cmgui you can reorder nodes and elements by any field, such as the x coordinate gfx change_identifier element_offset 1 sort_by coordinates.x.

If you want to use your xi directions to reorder then use computed fields to build up a new ordering from an xi_texture_coordinate field. Unfortunately you cannot use this to reorder your nodes, just your elements. To do this you start with a seed element from which the xi_texture_coordinates will spread out. This example is for 2D elements so there are 2 components. The weights in the second field are to ensure that xi2 varies faster than xi1 (There are 8 elements in the xi2 direction). :

  gfx define field renumber_1 xi_texture_coordinates seed_element 5;
  gfx define field renumber sum_components field renumber_1 weights 8 1;
  gfx change_id element_offset 1 sort_by renumber