New accretion disk method (WORK IN PROGRESS)

[rthorvald]

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You are in the Solar system at a distance of 1 AU from the Sun. You can see the Earth.

> TURN LEFT

You can see the Moon.

> GO FORWARD

You are next to the Moon. You can see the Mare Tranquillitatis.

> GO TO ALNITAK

You travel across the light years of space to Alnitak. You see an O-type supergiant star.

Great! I remember playing games that really were like this in the early eighties. They could be just as evocative, if not more, than much of the graphics intensive stuff that is produced today...

- rthorvald

[Dollan]

You know, we could just produce material and develop so we cater to the most low-end system out there, but then Celestia would be something like this:

Code: Select all

You are in the Solar system at a distance of 1 AU from the Sun. You can see the Earth.

> TURN LEFT

You can see the Moon.

> GO FORWARD

You are next to the Moon. You can see the Mare Tranquillitatis.

> GO TO ALNITAK

You travel across the light years of space to Alnitak. You see an O-type supergiant star.

Whoa. MAJOR flashback! I have this great urge to type "light cigar"... which, of course, opens up Dracula's "coffin".... Now I only hope that I have a stake in my inventory....

**chuckles** Ah, it's been a long day.

...John...

[ajtribick]

Ok, now back to the subject of the thread...

I've tried out the add-on and I'm getting the central planet drawn in front of the particles, regardless of whether the particles are in front of or behind the planet, even in the OpenGL 2.0 path. Is this a v1.4.1 bug that has been corrected in the v1.5.0 prereleases?

[Cham]

I've tried out the add-on and I'm getting the central planet drawn in front of the particles, regardless of whether the particles are in front of or behind the planet, even in the OpenGL 2.0 path. Is this a v1.4.1 bug that has been corrected in the v1.5.0 prereleases?

Most probably, yes.

You should try it with 1.5.0.

I'm now starting experiments on the sprites.

[fungun]

Ok being a newbie here. How do you change the color of the disk. I tried all the diff models, but they're all purple. Would rather have grey or a dirty color.

Thanx
Tim

[Cham]

Ok being a newbie here. How do you change the color of the disk. I tried all the diff models, but they're all purple. Would rather have grey or a dirty color.

fungun,

changing the color is easy : just open the model with your TEXT editor (the dots models are simple text files). At the beginning of the data, there are some material definitions. Just change the color (three diffuse parameters) as you wish.

[buggs_moran]

We really need an option, in the SSC or in the CMOD file itself, to tell Celestia to add a decrease of luminosity or opacity over distance. Then all sorts of things would be made possible with this technique.

In light of some new work I am doing with Celestia, I would like to strongly second this possibility. I would like the ability in the ssc. Perhaps as a switch like Emissive true and then a distance to fade.

Unless the switch is used, Celestia should consider the cmods as non diminishing (like Selden's graticules).

[Fenerit]

That's pretty cool... looks like it could come in handy for modelling star systems containing dust rings, e.g. Beta Pictoris.

Very dangerous for a vessel. Remember Pitch Black?

[Fenerit]

Can you reproduce a star which explode

Cham, can you reproduce single spheres of points colored as the spectrum? Your metod is that right for the granularity and the star's interiors. Even without cross-sections. For the heat, one could use the cloud's trick and for the spots, the point sprites.

[Cham]

There are tons of nice tricks I can do, using the dots distributions, and sprites. Unfortunately, the sprites aren't working on the Mac yet (buggy drivers), and Chris is gone. So all my projects are on hold, most probably for a very long period of time.

[Fenerit]

There are tons of nice tricks I can do, using the dots distributions, and sprites. Unfortunately, the sprites aren't working on the Mac yet (buggy drivers), and Chris is gone. So all my projects are on hold, most probably for a very long period of time.

I've read about point sprites and the Mac. Well, once resolved, you cannot say of not having add-ons where to work on!

[**CoSmO**]

Grrr im such a noob, i downloaded ur addon a while ago and it doesnt work

[ANDREA]

Hello Vincent, I'm very interested to use your Asteroid Main Belt rendering using point sprites cmod, in the Solar Systems project I'm working on, together with Buggs Moran. Is it available for use on 1.5.0?
If yes, can it be modified to allow its use for the Oort cloud too?

Andrea, Please, feel free to use and modify the Asteroid Main Belt model in your project. Since Martin originally created the point sprite cmod for his accretion disk model, you may just add something like "original model by Cham, modified by Vincent for the Lua Edu Tools" in your readme. You can of course also modify it to build a model of the Oort cloud. This will work with 1.5.0, except that the luminosity of the point sprites won't fade with distance...

Thanks a lot, Vincent, I downloaded the Lua Edu tools, copied the Asteroid belt directory into extras of my Celestia 1.5.0 installation, and obviously it works fine, and I can only say it's wonderful, so thanks to Cham and you.
But here is my little problem, and I think it's for Cham: I have to put the Asteroid Belt (and the Oort Cloud, too) at not real distances from the Sun.
I mean that the various Solar Systems we are producing are ?€?concentrated?€

[Vincent]

Now my problem is: how can I modify it so that, e.g., the belt will have reduced both its average distance from the Sun AND its width (min-max distance from the Sun, closer each other than in realty)?

Andrea,

You may want to try giving the Radius a smaller value in the ssc definition.

[Cham]

I think I understand what Andrea wants.

Changing the Radius in the SSC isn't enough, if we want to change the relative proportion of the ring's width with respect to its radius. If this is the case, we need to change the model itself, and we can't do it simply by editing the CMOD file. We need to run Mathematica with some new parameters (relative width and radius) and build a new model. I can do it very easily, since my Mathematica notebook is already done for this task.

There are several parameters to consider here, since the ring is actually a flatened torus :

Mean Radius
Mean Width
Ring Thickness
statistical distribution (there are several : gaussian, exponential, etc. Gaussian is the most "natural" looking distribution)

It's the same for the Oort shell I made (mean Radius, Mean width, statistics).

[buggs_moran]

I don't know Andrea. I think you might have to drop the planet sizes or increase the Mars-Jupiter Gap either way... If you put any belt into the current model it would be too thin to my eyes...

You could enlarge that gap in your model seeing how Jupiter is roughly 3 times further out than Mars to accommodate that asteroid belt...

[ANDREA]

Sorry for my late reply, I was out for my wife's birthday dinner at Restaurant (well, once a year?€¦ ).
Vincent, many thanks for your suggestion, it was so easy!
I still was considering the radius as regarding ONE single body, and I was considering the Asteroid Belt as a crowd of tiny single bodies, instead of a single body.
My stupid fault, sorry.
I tried, and here the results:





I think the Main Belt is correctly shaped for my needs, but obviously the Oort Cloud here is a belt, not a sphere.
Cham, as I see you was working on it, and here
http://celestiaproject.net/forum/viewtopic.php ... c&start=15
you give an example (Thick shell of dust), but I have seen nothing else on the matter.
Did you finish this improvement?
If yes, is it available?
Cham and Buggs, thanks for your suggestions, but fortunately a fine tuning of Asteroid 1 and Asteroid 2 radii in the ssc file allowed me to create the right width of the belt, so no need of further calculations with Mathematica, thanks.
If the Oort shell will be available, I think that to avoid the Asteroid Belt luminosity increase with distance, I will use for this the old method of about 3400 tiny bodies, and the cmod shell for the Oort Cloud.
This IMO should give me the possibility to tune the luminosities in a better way, until Chris will satisfy our request to solve this problem (let?€™s hope in a next release).
Thanks a lot to all of you for your precious help, very appreciated.
Bye

Andrea

[Cham]

Andrea,

I already have a nice working Oort spherical shell, at a proper distance. The result is satisfying, despite the luminosity problem with scale.

The zipped addon is only 260 KB, so I can send it to you by email. I like the result pretty much.

[ANDREA]

Andrea, I already have a nice working Oort spherical shell, at a proper distance. The result is satisfying, despite the luminosity problem with scale.
The zipped addon is only 260 KB, so I can send it to you by email. I like the result pretty much.

Thanks a lot, Martin, just sent you my email address by PM.
Bye

Andrea

[Hungry4info]

The zipped addon is only 260 KB, so I can send it to you by email. I like the result pretty much.

If it isn't too much to ask, would you please do the same for me? E-mail address is in profile.