The grid files consist of an equally spaced grid with values at the node points of the grid, which is used for cutting planes and isosurfaces. The grid files are in the following format.
VTE 1.4 ascii
GRID
NODES 2 2 2
SPACING 1 1 1
ORIGIN 0 0 0
COMPONENTS 2 rho phi
FRAME
0 0 1 2 2 4 3 6 4 8 5 10 6 12 7 14 8 16
FRAME_END
GRID_END
The nodes, spacing, and origin are in the format:
X Direction Y Direction Z Direction
The numbers under frame depend on the number of components you have, but is essentially the same as the demo here:
rho (node1) phi (node 1) rho (node 2) phi (node 2) rho (node 3) phi (node 3)......
The nodes are numbered in the x direction, then the y direction, and finally in the z direction. Therefore the nodes here would be:
0 0 0
1 0 0
0 1 0
1 1 0
0 0 1
1 0 1
0 1 1
1 1 1