A polar axis for Celestial objects

[selden]

This Addon can be used to draw an axial line through an SSC body. It's defined using Celestia's CMOD mesh object, so it only works with Celestia v1.3.2 or later.

More details are available at
http://www.lepp.cornell.edu/~seb/celestia/graticules.html#5




It's available in
http://www.lepp.cornell.edu/~seb/celestia/cmod_axis.zip (2KB)

If you restore this Zip archive into your Addons (or extras) folder, it should create its files in all the necessary sub-directories.

axis.cmod is a text file in the models folder.
The northern half of the axis is green.
The southern half of the axis is red.
You can edit axis.cmod to change these colors as you wish.

The included example SSC catalog file, mars-axis.ssc, demonstrates the use of the model to draw an axial line through Mars.

[Cham]

There's a small problem with this addon, Selden. The _Mars axis name is overlapping on the Mars name. Is there a way to remove the axis name ?

This axis should be made standard for all bodies in Celestia.

[selden]

Cham,

The quickest fix is to change the name of the Axis to " " -- just a space. I'll add that as a comment to the ssc file.

My understanding is that Chris is intending that a future version of Celestia will make objects non-selectable and their names non-printable if their names start with an underscore. That hasn't happened yet, though.

[Cham]

By the way, could you explain to me the uses of those 16 blue ticks around the planets, in Celestia 1.3.2 ? I'm a bit puzzled about them.

[selden]

The blue ticks are intended to indicate azimuthal directions when your viewpoint is on the ground. Chris was intending to give them labels and a separate selection method, but I think he may have forgotten. Right now they always appear when "Show Celestial Grid" is enabled.

[Cham]

Thanks. This feature could be usefull. Especially with the labels.

[ANDREA]

This Addon can be used to draw an axial line through an SSC body. It's defined using Celestia's CMOD mesh object, so it only works with Celestia v1.3.2 or later..

Hello Selden, just a couple days ago I was showing to students Harry's nineplanets_v1.0.celx, and while doing it I was thinkink
"how nice would be it if the polar axis could be shown, to indicate the different 9 planets axes inclinations!"
Well, here it is!
Very nice.
Just a little question: is it possible to change the length of the axis, North and South?
Thanks a lot anyhow.
By

Andrea

[selden]

Andrea,

I'm glad you like it

The total length of the axis is controlled by the Radius that you specify in its SSC file.

If your planet has a Radius of 2000 km and you specify an Axis Radius of 3000 km, the Axis will protrude 1000 km on both sides of the planet.

Is that what you're asking?

I didn't try to make it possible to make the north end stick out further than the south end.

However, the two ends of the axis have different materials in the CMOD file. You can completely eliminate either end of the axis by changing its Opacity from 1.0 to 0.0, if you want.

[ANDREA]

Andrea, I'm glad you like it The total length of the axis is controlled by the Radius that you specify in its SSC file.
If your planet has a Radius of 2000 km and you specify an Axis Radius of 3000 km, the Axis will protrude 1000 km on both sides of the planet.
Is that what you're asking?
I didn't try to make it possible to make the north end stick out further than the south end, though.

Wow Selden, the quickest reply I've seen in a Forum.
And, yes, this is exactly what I was asking for, thank you.
The reason is that, as in your Mars image, the planet can cover one of the two semiaxes, making less clear their function.
Now it's perfect, thank you very much.
I'm sorry not to be able to give any help, but this is not for my will, but only for my total ignorance on programming, and I'm too old to start now.
The only thing I can do, is to appreciate and thank all the people that like you, modestly and without playing a fanfare, make Celestia alive and growing more and more beautiful and useful.
So, for what this can be worthwhile,
THANK YOU EVERYBODY!

Andrea