This is a description of the polygons lines as used by MNI-Display
A file looks like: and means:
L 1 10 # line_width=1 npoints=10
63.7483 -0.0488046 25.3558 # x y z for point 0
-62.3075 0.616629 25.0492 # x y z for point 1
. .
. .
. .
-0.319302 -5.36752 -5.124 # x y z for point n_points-2
-0.277344 -6.09656 -5.0817 # x y z for point n_points-1
3 # number of line curves=3
0 .5 .6 .7 1 # 0 == one colour for entire lines
(r=.5 g=.6 b=.7 a=1)
4 7 11 # end indices of lines
first line has 4 vertices
second line has 3 vertices
third line has 4 vertices
0 1 2 3 # indices of the lines (the number of these
4 5 6 should be the last number of the end_indices,
7 8 9 2 i.e., there are 11 indices)