Hi folks,

About odd lines from overlays: as you may have begun to guess, we
have not one, but two, problems here.

One is that, if you zoom in far enough, the overlay lines start
to curl up and create zingers all over the screen. This appears to
happen because the endpoints of the lines are more than 2^16 = 65536
pixels apart (may be half that, I'm not totally sure.) I think it's
just some leftover 16-bit limitation in Windows' graphics routines.

Most people don't see this, because by default, the constellation
lines and boundary lines are not shown below a nine-degree FOV. But
some people have mentioned to me that they've reset that limit to,
say, zero degrees, and seen the zingers. It finally got to the
point that, a month or two ago, I added a bit of code to clip the
line segments _before_ passing them off to Windows. Presto, no
more zingers.

The second problem is in orthographic projection only. You may
recall that several new projections (including some "all-sky" ones)
were added to the 4 May 2002 update. Those required me to make a
slew of changes in how Guide handled error cases (mostly points
and line that are mathematical singularities). In the process,
I "broke" the orthographic projection.

Some people use the orthographic projection on Earth eclipse/
transit/occultation charts, to get an "Earth from space" view.
But it's rarely used on star charts, so I'm not surprised this
particular bug went unnoticed for three months.

Anyway, I will be posting a "bug fix" update this evening,
to cover these two plus assorted other fixes made recently.

A fix for the telescope control troubles, though, will not
be among them. One reason it's been a while since I posted an
update is that I'm working on ripping out Guide's current scope
control system and rigging up a new one. But that part is not
really ready for testing yet. (All you will see for improvements
will be a few more projections, plus a fix supplied by Arild
Moland: the menus now are more "Windows-standard", with "..."
used to indicate options leading to dialog boxes.)

Also: if you look at the "extras" page,

http://www.projectpluto.com/extras.htm

you'll see that four new user-added datasets have been appended
recently. These allow display of a new open-cluster catalog, a
list of AstroPhysics calibration stars (kindly provided by
Thomas Wichmann), and substantial updates to the CCDM (Catalogue
of Components of Double & Multiple Stars) and the WDS (Washington
Double Star catalogue).

-- Bill