Dagger

[1.5.X] Tilt'Em (Planetary axial tilt) [v1.0.0] [25 Oct 2018]

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Tilt'Em

Adds planetary axial tilt for KSP planets

Licence: MIT (don't even ask me for permission to fork it ;))

Download link Installation instructions Source code

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I always wanted to have planetary axial tilt with the default planets but I've always read that it was impossible to do it on unity. Principia managed to do it, but you have to use it's cool but complex n-body physics.

This mod adds axial tilt to the default planets and keeps the default KSP 2-body physics. Follow the installation instructions to check how to install it and how to edit the planet tilts for each individual planet

Edited by Dagger

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This is going to be quite amazing for us planet modders! We are going to give this thing a lot of use.

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I lift my hat to honour such accomplishment. Though it really was impossible. But you did it. Congrats.

Edited by GrandProtectorDark
Non intentional hat kid pun

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1 minute ago, Pkmniako said:

This is going to be quite amazing for us planet modders! We are going to give this thing a lot of use.

I'm working on it to make it as a kopernicus addon so better don't use it in your planet packs still ;)

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Would you mind if we index this in CKAN, before we get hit with dozens of planet packs adding it as a dependency? :)

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Just now, HebaruSan said:

Would you mind if we index this in CKAN, before we get hit with dozens of planet packs adding it as a dependency? :)

I honestly don't know how CKAN works but feel free to do it altough I'm working in a custom plugin for Kopernicus atm.

Also if you need to upload some file to the repo do a PR ;)

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Once more the KSP modding community proves that nothing is impossible in KSP, it just needs the right "stuff" to make it happen! :D

Kudos to @Dagger!

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Amazing work, this job will change everything, congratulations sir, you make history when you prove that is possible. 

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And it looks like you're 2-for-2 with amazing mods so far...

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I have no interest in this mod right now, but it is really cool to see it available!  I'll definitely file it away in the mods I'll use someday folder!

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1 hour ago, Dagger said:

  Principia managed to do it, but you have to use it's cool but complex n-body physics.

Fun fact: Principia is still not perfect regarding axial tilt. If you have a spin-stabilized spacecraft (fixed rotational axis) with no means of control (no reaction wheels or RCS) then this axis will be changed upon "SOI" change. This can be just a major annoyance, especially if you absolutely depend upon that spin (e.g. planning a capture using only solid rocket motors).

Looks like that this should not be a problem using this plugin!

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3 minutes ago, Phineas Freak said:

Fun fact: Principia is still not perfect regarding axial tilt. If you have a spin-stabilized spacecraft (fixed rotational axis) with no means of control (no reaction wheels or RCS) then this axis will be changed upon "SOI" change. This can be just a major annoyance, especially if you absolutely depend upon that spin (e.g. planning a capture using only solid rocket motors).

Looks like that this should not be a problem using this plugin!

To be honest I didn't tested it in every single case but any bug you found let me know ;) 

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@Dagger, this is interesting.  Congrats on figuring it out.  I have a couple questions:

1)  Can the direction of tilt be specified?  I understand that I can tilt an axis X degrees, but can I say I want to tilt it X degrees in the direction of Y longitude?  Or do all the axes tilt in the same direction?

2)  Does this have any affect on the coordinate system used for orbiting spacecraft?  For example, will the inclination of a spacecraft's orbit be in reference to the ecliptic, or to the planet's tilted equator?

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10 minutes ago, OhioBob said:

@Dagger, this is interesting.  Congrats on figuring it out.  I have a couple questions:

1)  Can the direction of tilt be specified?  I understand that I can tilt an axis X degrees, but can I say I want to tilt it X degrees in the direction of Y longitude?  Or do all the axes tilt in the same direction?

2)  Does this have any affect on the coordinate system used for orbiting spacecraft?  For example, will the inclination of a spacecraft's orbit be in reference to the ecliptic, or to the planet's tilted equator?

When talking about axial tilts you are only talking about the angle of the rotation of the planet against the ecliptic so for now I only accept 1 value for it but shouldn't be difficult to add more degrees to it.

Remember that the axial tilt of a planet is the same during all the orbit. It doesn't rotate/moves (technically it changes by very few degrees but it takes thousands of years

uXA9E24WQMqXYt0j2KUk

The coordinates and orbits of the vessels are not dependent on the axial tilt of the planet so from what I saw it works "fine" (fingers crossed ;))

Example: This is how a 90º orbit looks like when Kerbin is tilted:

4HgGNyr.png

Edited by Dagger

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@Dagger, I understand that the axial tilt is constant for a particular planet.  (Of course in real life there is axial precession, but that's not we're talking about.)  What I mean to ask is this...  In the image you post, Earth's axis in tilted toward the right.  Using your mod, will all other planets to which I give an axial tilt also have their axes tilted toward the right.  Or is it possible, for example, to have one planet's axis tilted to the right, and another planet's axis tilted to the left (or toward us or away from us).

 

Edited by OhioBob

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2 minutes ago, OhioBob said:

@Dagger, I understand that the axial tilt is constant for a particular planet.  (Of course in real life there is axial precession, but that's not we're talking about.)  What I mean to ask is this...  In the image you post, Earth's axis in tilted toward the right.  Using your mod, will all other planets to which I give an axial tilt also have their axes tilted toward the right.  Or is it possible, for example, to have one planet's axis tilted to the right, and another planet's axis tilted to the left.

Each planet can have it's own axial tilt. ;) You can configure them in the .cfg file

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i.e. If the body is spinning around its Y-Axis by default, can we specify the amount of inclination for the tilt in both the X and Z-Axis to have better control over how the body is oriented with respect to the 0-UT Epoch.

9KgUe.png

 

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1 minute ago, Poodmund said:

i.e. If the body is spinning around its Y-Axis by default, can we specify the amount of inclination for the tilt in both the X and Z-Axis to have better control over how the body is oriented with respect to the 0-UT Epoch.

9KgUe.png

 

Yeah That's the only case where 3 axis are useful, for the T=0. Will make a patch and add both values once I get the kopernicus patch

Edited by Dagger

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1 hour ago, Dagger said:

I honestly don't know how CKAN works but feel free to do it altough I'm working in a custom plugin for Kopernicus atm.

Sounds good, thanks. Will the Kopernicus plugin be submitted to be part of Kopernicus itself, or will it still be a part of TiltEm? Asking because if you're going to integrate this into Kopernicus, then it might not be necessary to index it as a separate mod.

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In real life there are many different coordinate systems used.  We usually define a spacecraft's orbit and position relative to the body it is orbiting.  For spacecraft orbiting Earth we use a geocentric-equatorial system, and for those orbiting the Sun we use a heliocentric-ecliptic system.  In KSP everything is relative to the ecliptic because none of the planets have axial tilt.  But if we were to introduce tilt to Kerbin, for example, I'm guessing that KSP will continue to use the ecliptic system even when in orbit of Kerbin.  That could introduce some problems, though I'm not entirely sure what the ramifications are.  It could be very confusing at the least.

(edit)  I think one of the potential problems is if we are trying to target some specific spot on the planet for a landing.  We would really need, in that case, a geocentric-equatorial coordinate system.  I realize this is probably way more than you've considered at this point.  But being able to have alternate coordinate systems is probably something that needs to be addressed in the future to take full advantage of axial tilt.
 

Edited by OhioBob

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Dumb (??) question:

Will this "break" contracts for specific orbits?
(Considering the fact that ContractConfigurator is picky and many contracts create issues whatsoever :D )

Edited by Gordon Dry

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