Comets, using the new asteroid generation system

[Red Iron Crown]

Yes, they shouldn't leave the Sun's SOI, by out system I meant outside Eeloo's orbit. Sorry for my imprecise phrasing.

I guess they should appear when they get close enough to the Sun to start outgassing on their way inward, as that's what makes comets easily detectable. What distance that should be may have to be different from reality given the Kerbol system's smaller scale.

[kerbonaut101]

Yes, they shouldn't leave the Sun's SOI, by out system I meant outside Eeloo's orbit. Sorry for my imprecise phrasing.

I guess they should appear when they get close enough to the Sun to start outgassing on their way inward, as that's what makes comets easily detectable. What distance that should be may have to be different from reality given the Kerbol system's smaller scale.

It does kinda make more sense to have them appear in the inner solar system where there more easily detectable (as in real life). As stated in another post, comets should have a chance of impacting the Sun (instead of Kerbin) (you wouldn't want to send a manned mission to a 'sun impacter'...)

Kerbins orbit is 13,599,840,256m by 13,599,840,256m so perhaps comets should start generating from 18,000,000,000m inwards (Dunas orbit is 21,783,189,163m by 19,669,121,365m)?

Edited March 30, 2014 by kerbonaut101

[NERVAfan]

How to achieve the tail effect (especially given their size) is something I have wondered about many times. It's hard to imagine how that could be done without volumetric, which I don't think the game currently supports. It's easy to fake an atmosphere because of its shape, but a comet tail?

I think the tail would be pure graphics, and maybe even only really visible from a distance. Comet tails are incredibly thin.

The coma could be modeled as an actual really thin atmosphere, I guess, or could be just graphics also.

EDIT: Maybe Squad could add comets this fall (September or early October) and put one (not randomly generated) in a close pass by Duna to celebrate/connect to the very close Mars approach (October 19 of this year) of Comet Siding Spring...

Edited March 30, 2014 by NERVAfan

[Shna_na]

How to achieve the tail effect (especially given their size) is something I have wondered about many times. It's hard to imagine how that could be done without volumetric, which I don't think the game currently supports. It's easy to fake an atmosphere because of its shape, but a comet tail?

I think it would be quite simple. They've already done it with the re-entry effects. Allow me to explain:

A comet's tail doesn't face retrograde, it just faces the opposite direction to the sun. In the re-entry heat effects, the game generates non-collidable "hairs" on the craft depending on direction and surface etc. and lights it from the prograde direction based on speed. For comets, the light detection system used in solar panels could be mashed with this to make it so that the side that has light coming from the sun has an intensified lighting in a pale blue (like this?), but instead of it using hairs it could use... Well, that's the hard part. Maybe the debris system? When a part explodes, little bits of debris rain out from a little poof of fire, yes? Well, these things could be produced and have their colour set by the light (the pale blue one) thanks to the comet being lit from the other side. So these debris pieces would be ejected from the side that detects no sunlight, while a light source is in front of the comet and lighting these up, in the same way that re-entry heat is generated.

Does this make sense? It's kind of rambley and rough around the edges but I think my point is clear enough. Comets are feasible, with some work put into them.

[kerbonaut101]

I think the tail would be pure graphics, and maybe even only really visible from a distance. Comet tails are incredibly thin.

The coma could be modeled as an actual really thin atmosphere, I guess, or could be just graphics also.

EDIT: Maybe Squad could add comets this fall (September or early October) and put one (not randomly generated) in a close pass by Duna to celebrate/connect to the very close Mars approach (October 19 of this year) of Comet Siding Spring...

That would be pretty cool imagine trying to launch a manned lander from Duna to try and intercept it... or you could have probes in Duna orbit waiting for it... perhaps we could have a few comets that are not randomly generated, that are based on famous real life ones (Halleys & ISON are the only ones I can think of at the moment)

Edited March 30, 2014 by kerbonaut101

[zeel]

I don't really think comets should be generated like asteroids. Rather they should just be very small and highly eccentric celestial bodies.

[boomerdog2000]

I don't really think comets should be generated like asteroids. Rather they should just be very small and highly eccentric celestial bodies.

I respect your opinion, but why do you think that?

[Alex_Leonardo]

How about a comet that crashes into kerbin.

(Cometorite?)

[MKI]

Comets should be Movable to Asteroids but not Generated like them. Unlike Asteroids a comet flyby of Kerbin would be a spectacle, and view able from the Surface. And just like real life they should only come once in a while, not constantly like Asteroids.

I say they can be movable Like Asteroids and can be interacted with them similarly.

My only issue is how to make the Comet's tail? Such a large thing should have an FX trail and that screams lag. This is why i doubt comets would arrive any time soon, plus Asteroids have caused the Dev team a lot of trouble already and adding another mobile body could bring more problems.

They could be on rails, which would be just as nice and act like a mini planet, but the same FX problems would still be persistent.

[NovaSilisko]

I respect your opinion, but why do you think that?

Because real comets behave nothing like how KSP's asteroids behave. They come screaming in from highly eccentric orbits around the sun, only very very rarely coming close to earth. Comet Hale-Bopp, for instance, never got closer to Earth than 1.3 AU. KSP's asteroids (to my knowledge) only appear in or around Kerbin's sphere of influence after you track them in the tracking station. Comets, on the other hand, would be discovered as they begin heating up and emitting gas - thereby becoming bright enough to be visible.

I doubt most comets would be movable, though, even at KSP scales. Maybe the odd relatively-microscopic one could be pushed around, but that wouldn't be a very spectacular one. Comet ISON, for instance, was ~2 km across, and was barely visible from Earth before its untimely demise. Something 20m across wouldn't even be noticeable.

Such a large thing should have an FX trail and that screams lag.

Hardly, it would just be a particle system (or maybe some sort of shader?), and it would be simulated VERY slowly (only moving relatively quickly when at max timewarp). It would arguably be cheaper than the particles coming out of a single rocket engine.

Edited March 30, 2014 by NovaSilisko

[kerbonaut101]

Comets should be Movable to Asteroids but not Generated like them.

My only issue is how to make the Comet's tail? Such a large thing should have an FX trail and that screams lag. .

Well, I did say in an earlier post that when they are generated they should be placed in a highly eccentric orbit that brings them close to the Sun (10,000m?) and then back out way beyond the orbit of Eeloo into the KSP equivalent of the Kuiperbelt

In regards to the size of the comet, ins't KSP's scale something like 1/10? So, a comet ISON equivalent would only be 200m3, not very big as far as celestial bodies go. They should have a tail and i'm hoping that will be worked out ( i like the idea of using a modified version of the reentry effects that was mentioned in another post, that way, maybe the comet tail could intensify as it nears the Sun and dissipate as it moves further away)

Edited March 30, 2014 by kerbonaut101

[boomerdog2000]

Because real comets behave nothing like how KSP's asteroids behave. They come screaming in from highly eccentric orbits around the sun, only very very rarely coming close to earth. Comet Hale-Bopp, for instance, never got closer to Earth than 1.3 AU. KSP's asteroids (to my knowledge) only appear in or around Kerbin's sphere of influence after you track them in the tracking station. Comets, on the other hand, would be discovered as they begin heating up and emitting gas - thereby becoming bright enough to be visible.

Which is exactly why we talked about earlier generating them around the sun instead where the outgassing would be greater. I realize the orbits wouldn't be the same and that's not what I was suggesting. The system to create them is relatively the same just with a few minor tweaks. Instead of around Kerbin the trackable objects appear around the sun. Instead of a near circular orbit they have a highly elliptical one.

[kerbonaut101]

Which is exactly why we talkehd about earlier generating them around the sun instead where the outgassing would be greater. I realize the orbits wouldn't be the same and that's not what I was suggesting. The system to create them is relatively the same just with a few minor tweaks. Instead of around Kerbin the trackable objects appear around the sun. Instead of a near circular orbit they have a highly elliptical one.

Yep, it's just the comet tail effects that may take time to figure out and get it working satisfactorily.

If the reentry effects are used perhaps the tail should be generated from Dunas orbit inwards? Because in real life, Mars is on the edge of the habitable zone in which liquid water can exist

[edit] Ive thought of something that could be an average orbit for procedural comets, 2,500,000m by 175,000,000,000m

Edited March 30, 2014 by kerbonaut101

[vger]

Volumetric lights/fog seems to me the best way to simulate a comet tail. I don't know if that would be too much of a performance hog or not though. A lot of the lag-fest games that support it, use it EVERYWHERE. But just one or two light sources, where the only thing around that can possibly cast a shadow is a ship?

[kerbonaut101]

Volumetric lights/fog seems to me the best way to simulate a comet tail. I don't know if that would be too much of a performance hog or not though. A lot of the lag-fest games that support it, use it EVERYWHERE. But just one or two light sources, where the only thing around that can possibly cast a shadow is a ship?

Yeah, but I suppose you could change the quality of it in the graphics settings? And if the comet becomes permanent only when you click 'track object' it shouldn't be to much of a resource hog. Im not sure if you could attach biomes to that though

Edited March 30, 2014 by kerbonaut101

[kerbonaut101]

I've been thinking, how much should the inclination vary with comets? Should we get some coming in polar orbits or should they stay near equatorial orbit around the Sun or something in-between (I think I would prefer the orbital inclination to be generated completely randomly, if this is possible)?

Edited March 30, 2014 by kerbonaut101

[vger]

Yeah, but I suppose you could change the quality of it in the graphics settings? And if the comet becomes permanent only when you click 'track object' it shouldn't be to much of a resource hog. Im not sure if you could attach biomes to that though

I've got a picture in my mind of how it could work. If I get REALLY bored later, maybe I'll post some pictures. I'll try to explain it in text though.

#1. The 'biome map' spins independently of the nucleus, so that the 'tail' biomes always point away from the sun.

#2. A duplicate of the biome map, serves as the spotlight mask. Where the ion and dust biomes are, you have holes cut in the mask (with slightly different colors if you wish) through which a light source at the center of the comet can shine.

As long as the light mask and the biome map line up, you'll get your biomes exactly where they should be, relative to the tail effects.

The H corona can just be done with the same FX that are used for atmospheres.

Edited March 30, 2014 by vger

[Space_Kraken]

Novasilsko made comets with tails in his Alternis Kerbol mod. Maybe he can share the code with somebody willing to make this a reality.

[Alex_Leonardo]

Just to add in:

Comets. (Good)

Comets with atmospheres. (Awesome!)

[*Aqua*]

Why should they have an atmosphere? They don't have enough gravity to keep it.

[kerbonaut101]

Why should they have an atmosphere? They don't have enough gravity to keep it.

Yeah the comet would have to so big that it would be considered a planet.

[edit] btw... 1000+ views I posted this suggestion thinking i'd never hear from it again.... *feeling happy*

Edited March 31, 2014 by kerbonaut101

[vger]

Why should they have an atmosphere? They don't have enough gravity to keep it.

It's not literally an atmosphere. It's just that the atmosphere portion of KSP's systems could be re-purposed for comets.

The coma and the tail, as far as the game is concerned, would function like an atmosphere.

[NovaSilisko]

Novasilsko made comets with tails in his Alternis Kerbol mod. Maybe he can share the code with somebody willing to make this a reality.

The plugin is (as all are) open source, so if anyone wants to...

I remember ages ago I tried doing the same with a particle effect, and it ended up problematic. Particles don't like time warp, or the shifts in space that occur in the tracking station...

[kerbonaut101]

The plugin is (as all are) open source, so if anyone wants to...

I remember ages ago I tried doing the same with a particle effect, and it ended up problematic. Particles don't like time warp, or the shifts in space that occur in the tracking station...

What actually happened? did the particles just end up stretching to an insane amount? Maybe the comet tail is something that'll have to be limited to 1x (or 10x) time-acceleration and it'll have to turn off if you go beyond that...

The really annoying thing about comets is the tail (I still think the idea of using a system similar to the reentry effects could work)

[NovaSilisko]

What actually happened? did the particles just end up stretching to an insane amount? Maybe the comet tail is something that'll have to be limited to 1x (or 10x) time-acceleration and it'll have to turn off if you go beyond that...

The really annoying thing about comets is the tail (I still the idea of using a system similar to the reentry effects could work)

Nah, they just jittered around a lot. To make them behave semi-realistically I had them set to simulate in world space so they would be "blown" away from the sun (as in, the particle effect aiming away from the sun and emitting outward), but it really didn't like that. I think it could be fixed if you set their simulation mode to local and instead calculated the force being applied to them to fake the same effect, but that'd be a nightmare of mathematics figuring out what the force should be at what given time...