Celestia Forums

I am well versed in creating objects in our own system, but I am having problems creating moons around extrasolar planets, even ones I have created. I have several extrasolar systems from other designers, and even when I replace file names, the objects cease to exist. I assume this is a simple problem and I am over-thinking. Please help.

Declan

The semimajor axis and period is in a different scale...axis is now in kilometers from the center of the parent planet and the period is in days instead of years...that could be the issue...also like in solarsys.ssc make sure you configure the moon labels the same in respect...

solar system
"moon" "earth/sol"

extra solar system
"moon" "planet/parent star"
"thor" "zeus/mira"

other than that you might want to post some of your scripting to see what you've got so far...

Declan,

Can you provide an example of a failing SSC specification?
Along with the most similar SSC that works?

It's hard to suggest what kind of mistakes might cause the symptoms you mention. There are too many possibilities. Usually when tracking down problems like this, it helps to reduce the system descriptions to the minimum that works, deleting everything that isn't absolutely necessary. Then introduce the changes you want one at a time until it stops working.

One problem with Celestia is that it is not very verbose when it detects errors. It just doesn't draw the associated object. Celestia will log some kinds of errors to a log file if you run it from a cmd or DOS window with a command that looks like
CELESTIA >logfilename
where 'logfilename' is whatever name you specify for the output file.

I hope this helps a little.

I will clarify,

I would love to believe it is simply that my units are out of wack and my moon is being drawn in strange positions or orbits, etc. But even in that case, right clicking on the parent body would result in a menu that contained the name of the associated moon.

As far as the particular line that fails in the code...I took a simple system like Mike's system, downloadable from the hub, and replaced a single planet texture name and all of its associated moons vanished. You see why this is strange?

So, first assume that all of the simple things have been eliminated, that I am well versed in the language and in other aspects of the program, and then troubleshoot. Other than that, there is no way to say which aspect of the code fails, because even the most simple, and I mean MOST simple orbital object, like an orbit...



...fails.

Now I try to translate that to the extrasolar object and it just won't render. Not the name or anything. What in the world is it?

There's two things I can think of that may be causing the problem:
1. you haven't saved the file in the /extras/ folder
2. the file hasn't been saved with a .ssc extension

jic your doing this at some point...period is set to zero when it goes past the 4th decimal place...when period is set to zero the object disappears....use 8e-5 instead...

Albedo will do the same when set to zero...

I tried all recommended courses of action. I am going to paste the actual code in and someone tell me what is wrong.


It won't even show that "Milly" is in orbit. This is very frustrating. And remember that when I use other peoples code and just replace the texture for the main body or moon, all moons disappear. This leads me to think it has less to do with the programing and more to do with some kind of size limit for each body. Like a memory cap. But that is rediculous. I am clueless.

You just have the order the star and planet reversed . . . it should be:



instead of:



--Chris

Chris is right about the names.
There is defenetly no cap on the amount of moons you can have. The system I work on has a gasgiant with ten moons as it stands and I am going to plug-in a few more.
The other thing to consider is if you plan on changing the texture for the extrasolar planet it can be done in 2 ways. The way I did it was I wrote a system in a .ssc file and then went into the extrasoloar.ssc and put the pound # and space in front of the said extrasoloar planet were it apeared in the text of the extrasolar.scc. This alows your add-on to take control. If you don't you will end up with 2 planets in the same orbit or they might draw inside each other. The second is to simply change the texture name in the extrasolar.scc for said planet. Again be sure that you don't list the main planet in your add-on.ssc or you will again have 2 planets ocupying this same orbit. I you plan on sharing your system with other users be sure you document witch way you chose to do it. If someone else installs you add-on and the don't have the info on the posible changes the add-on won't work right for them. Just some thouhgts.

Oops that always throws me off...the star then planet bit...

I tend to use the same code over and over...Once I get this planet builder Im working on sorted I think there will be alot less problems with making extrasolar systems...well I hope...

Another point: If you specify the SSC parameter CustomOrbit, you'll have to modify Celestia's source code. That parameter tells Celestia to select the C++ subroutine that was written especially to calculate the orbital position of the named object. You'll to provide that routine.

If you don't want to modify the source code, there are only two other options for specifying the orbit: SampledOrbit, which refers to a file containing a list of times and xyz coordinates relative to the parent object, and EllipticalOrbit, which requires you to provide some of the parameters needed to define a Keplerian (elliptical) orbit around the parent object.

Thomas Guilpain has written some French and English Web pages describing in detail most of the parameters available for use in an SSC file. The English version is at http://members.fortunecity.com/guilpain/index_uk.htm
I've written some rather cryptic notes that also mention some newer parameters. They're at http://www.lns.cornell.edu/~seb/celestia/celestia_notes.html

I hope this helps.

It was a foolish mistake. Thanks all so much for helping. I will post a picture of what I was trying to do. Just a nice moon at sunset for my girlfriend. It's the vulcanic moon I found on the hub. I think it's one of the coolest night textures going. I also know it's not realistic to put it around an earthlike planet, but gimme some slack! :D

Declan Royce