Hi,

does anybody have a working example how to add a user-defined horizon
line to the horizon.dat file?

I did try this code for a 90-degree segment of my horizon:

f 12 32 32 0
0   25
10  21
20  20
30  16
40  22
50  18
60  16
70  22
80  19
90  16
90 -10
0  -10

The problem is that sometimes Guide fills the area correctly, and
sometimes it fills the whole screen and sometimes it fills everything
else except the area to be filled. It depends on which point is centered
in the screen.

Any ideas?

Michael