FGA Point ordering

Hello all,

I am trying to extract FGA-type vector fields 1) by hand through formulas for the vectors and 2) from simulation data. Since our software stack does not support the conversion to FGA on its own, I have to generate those files with python.

In the following, I am referring to a cubic grid -1,1][SUP]3[/SUP]⊂ℝ[SUP]3[/SUP] I am creating with my python script using some dimensionality n and spacing d.

I have two questions:

  1. In what order do I write coordinates? From my testing, XYZ seems the correct ordering since after testing particles fly in the appropriate directions for the base vectors.
  2. In what order are the grid points? My most successful effort is z-planes with y-lines (In code: for z for y for x, or similar: sort coord-wise by z then mergesort y then mergesort x)

This only got me to the point where I optained a correct result for the halfspace {(0,0,1)[SUP]T[/SUP] where z < 0}. There, the lower (z-oriented) half of the box is showing values while the upper one does not, as intended. But the same for x < 0 or y < 0 does not work.
What point ordering does unreal want? There are not many possibilities I believe (xyz/xzy/zxy/zyx/yxz/xzy with adcending or descending coordinates respectively) but none I tried seem to be working, especially since I am quite sure of the z-plane thing (because the halfspace thing worked).