Celestia Forums

Add favicon support for info-url's.

Would be very nice to enhance info-url's appearance and clarity, clearness.
e.g. people who are visually impaired or find it easier to remember icons.

duds26 wrote:Request for adding spiral orbits.

They could be used for objects falling onto/into other objects.
(Simulation of attraction to a point.)

e.g. the orbit of objects falling into a black hole.
the orbit of a spaceship or meteor crashing on the moon or other planet.

Now for a link to make this complete: http://en.wikipedia.org/wiki/Spiral

A spiral orbit can already be created as a SampledTrajectory (.xyz or .xyzv file) or a ScriptedOrbit. The former is probably easiest, but you'd have to write code or use a spreadsheet to generate the points on the spiral.

--Chris

chris wrote:
...but you'd have to write code or use a spreadsheet to generate the points on the spiral.

--Chris

which is exceedingly trivial via polar coordinates:

[tex]r = c_1\,\exp{c_2\,\theta}[/tex]

where r is the distance from the origin, [tex]r=\sqrt{x^2+y^2 }[/tex], [tex]\theta[/tex] is the angle from the x-axis, and [tex]c_1, c_2[/tex] are arbitrary constants.

Fridger

The point of a spiral orbit is to be able to define a spiral-shaped orbit with the parameters.
Not with a bunch of plotted points, because then there is no point in it.

I'm trying to avoid approximating a spiral this way.
Because generating a lot of points to make it look good can have a lot of overhead.
Seems that I'll try to write a ScriptedOrbit for this sometime in the future.

Another example where spiral orbits would be good:
The moons of Mars, they are going to fall but it'll take some time.

@t00fri, good idea that you post that for anyone
(know these formulas because I'm a student engineering.)

Dunno if this has been requested before, but...

You know how the orbits of moons are locked to the obliquity of the parent planet?

How bout doing the same thing for planets orbiting stars and barycenters?

For that, we could have an additional file in the data directory that has the information of a star's axial tilt, or maybe adding the info to the already existing stc files in the data directory? Stars whose axial tilts are unknown would remain untouched, leaving them at the default obliquity for stars and barycenters.

I love the idea, PlutonianEmpire.

PlutonianEmpire wrote:Dunno if this has been requested before, but...

You know how the orbits of moons are locked to the obliquity of the parent planet?

How bout doing the same thing for planets orbiting stars and barycenters?

For that, we could have an additional file in the data directory that has the information of a star's axial tilt, or maybe adding the info to the already existing stc files in the data directory? Stars whose axial tilts are unknown would remain untouched, leaving them at the default obliquity for stars and barycenters.

I believe this feature already exists in the form of the MeanEquator reference frame.
http://en.wikibooks.org/wiki/Celestia/R ... r_property

Have you tried using that?

selden wrote:

PlutonianEmpire wrote:Dunno if this has been requested before, but...

You know how the orbits of moons are locked to the obliquity of the parent planet?

How bout doing the same thing for planets orbiting stars and barycenters?

For that, we could have an additional file in the data directory that has the information of a star's axial tilt, or maybe adding the info to the already existing stc files in the data directory? Stars whose axial tilts are unknown would remain untouched, leaving them at the default obliquity for stars and barycenters.

I believe this feature already exists in the form of the MeanEquator reference frame.
http://en.wikibooks.org/wiki/Celestia/R ... r_property

Have you tried using that?

I could, but from the looks of it, in the default version of celestia, there's no entry in the default stc file(s) pointing the bodies of stars in the right direction, and that trying to add the MeanEquator definition to the star to match its orbital plane wouldn't work. Unless there's a definition out there that I don't know that can do that?

I'm confused by your objection.

A star's definition has to include a tilt if you want to use its tilt
to define its planets' orbital plane. Most stars defined in Celestia
don't include a tilt because that information is not included in the
Hipparcos database. I suspect that their tilts have been measured for
only a few stars.

However, if you define a star with a tilt, that tilt can be
transferred to each of its planets by adding an appropriate OrbitFrame
declaration to each planet's SSC definition, overriding the
default. The default OrbitFrame for all planetary orbits is defined to
be relative to our own solar system's ecliptic. While it would be more
convenient for planetary system designers if the default were the
local star's rotational plane, that would break all of the current
exoplanets' orbital definitions.

Don't forget that you can use the Modify prefix in an STC file to add
an appropriate tilt to stars already known to Celestia.

Here's an example which defines a tilted star and its planet.

tilted_star.stc



tilted_planet.ssc

Is there any way to lock the local ecliptic to the orbits of stars in a binary system?

Not that I'm aware of.

selden wrote:tilted_star.stc

Code: Select all

"tilted_star"
{
   RA 1.1
   Dec 1.1
   Distance 1.1

   SpectralType "G2V"
   AbsMag 4.83

   UniformRotation
   {
       Period          100
       Inclination      45
       AscendingNode    90
       MeridianAngle    50
   }
}


Can this be done for barycenters as well?

I haven't tried it, so I don't know for sure.

Why don't you give it a try?

Feature Request:
Stars and exo-planets should have orbits relative to the system's barycenter.

The default OrbitFrame for all planetary orbits is defined to
be relative to our own solar system's ecliptic. While it would be more
convenient for planetary system designers if the default were the
local star's rotational plane, that would break all of the current
exoplanets' orbital definitions.

Not our star, not a star please. Using the barycenter is actually better because it's...the actual rotation point of the system.
It's mentally easy to grab and scientifically/programmatically it's a better starting point for describing orbits around.

The OrbitFrame should be relative to the barycenter.
Every solar system should have one.
Also every galaxy should have one.

About the compatibility:
The best way to avoid breaking stuff is to convert the data of the exo-planets, with a program/some algorithms.
Not by hand because it's tedious and including the algorithms in celestia enables backwards compatibility for addons. It would make it possible to convert the orbits silently while loading.
New addons could use a line of code that indicates using the newer system. Similar to the mesh scale problems a while back.

Feature request:
Changing language in Celestia in interface without restarting.

How it would work:
Making it possible to click on a menu and choose a language.
Celestia then loads the language file and updates it's texts without restarting.

Request:

I know this is a science software but it would be nice to be able to make lines between stars, with colors of choice, without having to make a cmod to do it.

Sorry if the request has been already done:

- When a planet is selected, we can, by right-click, select the moons.
- But when a moon is selected, we can't 'go back'. And sometimes the moon is far away from planet, so we must type the name of the planet to select it again...
- It would be great to have, for each object from satellite/object/something to star, the parent and the child(s) selectable by right-click.

Teto.
Great software, anyway.

Request:

An "export equirectangular image" function would be really nice, with a few (2:1) sizes to pick from, to be used in a QTVR panorama. I know that Celestia is already far better than a QTVR file, but those are nice to share with people as an example view from your addon. You could even make multi-node tours with hotspots, to really show it off.

I've made one QTVR from Celestia screenshots, but it took forever and it's still not perfect.

Apollonius wrote:Request:

An "export equirectangular image" function would be really nice, with a few (2:1) sizes to pick from, to be used in a QTVR panorama. I know that Celestia is already far better than a QTVR file, but those are nice to share with people as an example view from your addon. You could even make multi-node tours with hotspots, to really show it off.

I've made one QTVR from Celestia screenshots, but it took forever and it's still not perfect.

Seems like a cool feature and one that wouldn't be too hard to add. Do you have a link to information about the types of projections required by QTVR?

--Chris

Teto wrote:Sorry if the request has been already done:

- When a planet is selected, we can, by right-click, select the moons.
- But when a moon is selected, we can't 'go back'. And sometimes the moon is far away from planet, so we must type the name of the planet to select it again...
- It would be great to have, for each object from satellite/object/something to star, the parent and the child(s) selectable by right-click.

Teto.
Great software, anyway.

You can reselect the planet by typing it's number. If it's the 5th planet hit the 5 key. etc.