Celestia Forums

All the starts in celestia (and planets) all are confined to a certain area of the Milky Way and I was just wondering if this is because the program can only place them in this area or would it be possible to extend it.

I'm asking this because wouldn't it be then possible to make and entire galaxy up that you could go inside of (like this area).

It's a limitation of the OpenGL graphics system. Objects cannot be depth-sorted beyond a certain distance, and the single-precision floating-point numbers used by OpenGL lead to large inaccuracies beyond a certain distance.

Once I tried to put a globular cluster inside the Magallanice Cloud to see how it would like, but because those starts were outside the 16K light years limit, I cold not see them from earth, but when I went past the MC, looking at it and the Milky Way at the background, teh starts were visible...

You also might want to consider reading the "Preliminary User's FAQ", especially Q/A#12 Why are there no stars beyond about 16,000 light years?

So would this be simply a temporary OpenGL problem that might later get fixed or is it simply not possible?

gr8eagle8,

Please read the FAQ. It's discussed there.

I still think it could be possible to create different "origins" for the coordinate system that could be selected via a config file. So if you wanted something in the LMC, you could set a new co-ordinate origin in the middle of it and plant your stars up to 16,000 ly around it.

Or maybe just have different origins hardwired into the program, and hop from one to the other as you travel to them.

Oh Evil One,

My understanding is that there are intentions to include something like what you describe in some future version of Celestia.

How soon that actually might happen is impossible for me to guess. At the moment, Chris is the only one who understands Celestia, OpenGL and C++ well enough to write that code, and he has many other demands on his time.

If you want stars past 16k you will have to do just what the evil one mentioned...repositioning your world coordinates. This will however mess up your original coordinates or make eveything outside the new 16k barrier clipped as before. Chris will have to redo 90% of his plotting code in order to break the 16k barrier with a whole new approach...Unless he knows something I dont I think there will always be a 16k barrier...Light positioning for one doesnt allow more than a floating point coordinate system. Unless SGI comes out with improved light positioning Chris will have to revamp Celestia...

selden wrote:Oh Evil One,

My understanding is that there are intentions to include something like what you describe in some future version of Celestia.

Groovy. It's no big deal, but that seems to me to be the most practical way to get around the problem (short of doing something with double precision instead of single, but I dunno if that'd even be possible)