Making a Fantasy Game

[PhoneLobster]

The flying islands world is something I understand... maybe it's ...just magic.

...The hollow world, on the other hand, does not work, like, at all. The problem is not because of the lack of gravity (which, by the way, is not a matter of physics, that's motherfvcking MATH at work)

Congratulations you have very nearly mimicked perfectly the intellectual dissonance of the initial contentious statement by Frank. Floating Islands are OK because they are Magic, Hollow worlds aren't because of Science!

WTF?

In other news. "Really Big" is indeed a description.

Also the fact that You read one story that focused entirely about floating islands and another that focused entirely on a hollow world not only proves nothing, it is very nearly like saying nothing at all in the first place.

Indeed I am rather puzzled how "there was a story about it!" makes one acceptable while "there was a story about it!" makes the other unacceptable.

Especially when you add "and there COULD be a story not exclusively about one of those, no comment on the other" as further "evidence of... something...

Especially especially when this contradicts your initial claim that "there was a story about it(that focused on it almost exclusively)" was the way that it "should" be.

I also like how you take the time to talk about how the things you said weren't "the problem" with hollow worlds were in fact also the problem.

And I like how you wrapped up with a wandering three point summary about "1) There was a story about it, 2)There was a story about it, 3)There was a story about it" Thus because unlike floating islands (which there was a story about) they are all wrong-bad-fun.

I think you might need to thoroughly review and refine your thoughts on the matter.

[Grek]

Do you mind explaining that?

I posted a wiki link a long while back on the topic:

http://en.wikipedia.org/wiki/Shell_theorem

To quote the relevent bit:

Isaac Newton used shell theorem to show that:

• * A spherically symmetric body affects external objects gravitationally as though all of its mass were concentrated at a point at its center.

• * If the body is a spherically symmetric shell (i.e. a hollow ball), no gravitational force is exerted by the shell on any object inside, regardless of the object's location within the shell.

• * Inside a solid sphere of constant density the gravitational force varies linearly with distance from the center, becoming zero at the center of mass.

[virgil]

I thought Starmaker was making the point that hollow worlds don't add anything in terms of interaction. It'd be like changing the color of the sky in your setting to green, which feels like change for the sake of change, quickly forgotten unless you pointlessly remind everyone.

[Roog]

I posted a wiki link a long while back on the topic:

http://en.wikipedia.org/wiki/Shell_theorem

I know the physics of the situation, but you said...

The problem is not because of the lack of gravity (which, by the way, is not a matter of physics, that's motherfvcking MATH at work)

Its easy enough to define a "gravity" field inside the hollow world that will produce results that match common sense expectations. And if you don't want to make extra assumptions about that universe, you can ommit the assumption that the sphere has an outside.

[MartinHarper]

Do we think a hollow world setting (or a green sky setting) works better in a more visual medium than books?

The ways you interact with a hollow world are, that I can think of:
* straight-line vision
* straight-line travel
* journey from inside to outside and back
* crack the world
* borderline: perpetual sunlight.
* borderline: culture clash between inside and outside

[name_here]

And travel gets into all sorts of mucky issues which are the main point of dispute, and the huge distinction between flying islands and hollow worlds.

Namely, it is logically impossible for gravity to be at the same strength in the same direction for an entire straight-line journey, including landing. There will be a point where it weakens before strengthening or suddenly flips. Even in a repulsion sun with no inverse square law system, somthing which is launched in an arc that would with a consistant direction of gravity take it around the sun will get thrown in a weird pattern.

And the biggest issue, which I've mentioned before, is that you're changing laws of physics in ways that might actually come up in play for things which are not magical in and of themselves. Like a non-magic arrow.

[virgil]

Assuming the hollow sphere has a larger internal radius than Earth, then straight-line travel isn't going to be a problem. This hollow earth paradigm isn't spontaneously forming low orbit aircraft, so I don't see how this is something you should ever worry about within the confines of the genre/setting.

[Username17]

Assuming the hollow sphere has a larger internal radius than Earth, then straight-line travel isn't going to be a problem. This hollow earth paradigm isn't spontaneously forming low orbit aircraft, so I don't see how this is something you should ever worry about within the confines of the genre/setting.

If you aren't doing straight line travel, why the fuck would you even have a hollow world?

Seriously. What is the point of having something like that if you aren't going to use it? That's like letting Chekov's Gun rust right in front of everyone.

-Username17

[virgil]

As I said previously, that was the problem with using a Hollow World; a purely aesthetic change that doesn't influence actual gameplay.

[MartinHarper]

It is logically impossible for gravity to be at the same strength in the same direction for an entire straight-line journey, including landing.

Yes. It is very much like space travel in a solid world. It's also very much like straight line travel between mountain tops in a solid world. It shouldn't be particularly difficult for people to handle, though apparently it is.

You're changing laws of physics in ways that might actually come up in play for things which are not magical in and of themselves. Like a non-magic arrow.

If they come into play for regular arrows, and you don't intend that, then you're doing it wrong.

[CatharzGodfoot]

Namely, it is logically impossible for gravity to be at the same strength in the same direction for an entire straight-line journey, including landing. There will be a point where it weakens before strengthening or suddenly flips.

That's not a bug. That's a feature.

Even in a repulsion sun with no inverse square law system, somthing which is launched in an arc that would with a consistant direction of gravity take it around the sun will get thrown in a weird pattern.

A "weird pattern" such as a stretched ballistic arc? Not a problem.

And the biggest issue, which I've mentioned before, is that you're changing laws of physics in ways that might actually come up in play for things which are not magical in and of themselves. Like a non-magic arrow.

Again, not a problem. You don't even have to change the laws of physics directly. You can simply create some phlebotinum that interacts with them in a funny way (e.g. floatstone).

[name_here]

It is logically impossible for gravity to be at the same strength in the same direction for an entire straight-line journey, including landing.

Yes. It is very much like space travel in a solid world. It's also very much like straight line travel between mountain tops in a solid world. It shouldn't be particularly difficult for people to handle, though apparently it is.

You're changing laws of physics in ways that might actually come up in play for things which are not magical in and of themselves. Like a non-magic arrow.

If they come into play for regular arrows, and you don't intend that, then you're doing it wrong.

It's hard for people to deal with because that stuff matters hugely when it comes up, and unlike in a solid world you'll encounter gravity distorting the arcs of unsupported objects.

Like a non-magic arrow fired from an airship near the center, the second part of which i assumed was implied.

I'm thinking that the problem here may in part be fundamental confusion with what is meant by straight line travel. The black line in the image below is what i mean, the red is what i think you mean.



Red line flight may show minor effects, black line flight towards the middle of the trip will start showing extreme effects, one way or another. Or on landing if you do things the extra easy and insanely stupid way, when gravity changes direction only in close proximity to the ground, which is fine for arrows but not so much for airships.

---

That's not a bug. That's a feature.

It's also a great deal of math, which basically has to be done beforehand. However, at least you admit that it shows up, which means we can discuss whether we like that instead of whether that is precisely the same as some islands which fly.

A "weird pattern" such as a stretched ballistic arc? Not a problem.

Actually, that's indirectly an extreme problem because archers don't have math skillsofts to correct their aim on the fly. It'd play hell with aiming. I've done some archery, and it's hard enough to aim in the only gravity I've ever tried it in. If i tried it on the moon the arrow would miss hugely instead of only a bit.

But in the system i mention you'd actually have an even weirder pattern, because the arc isn't really an arc but rather some sort of squiggle, because "gravity" inverts by the high point of the arc. The problem is worse but also localized, with normal style gravity the problem is spread out but only shows up as screwing with accuracy instead of making attacks beyond a certain range totally impossible with projectiles that have mass.

EDIT: by a great deal of math, i don't mean for a given point, i mean for all the sections at whatever granularity we feel like simulating

[PhoneLobster]

It's also a great deal of math, which basically has to be done beforehand. However, at least you admit that it shows up, which means we can discuss whether we like that instead of whether that is precisely the same as some islands which fly.

Er. What?

In your strange universe do you have to run all the maths on the forces at play on horse and cart in motion before it can be included in your game w... oh wait, the pedantic 9 page float boat physics thread might suggest you do. There's medication for that condition you know.

Actually, that's indirectly an extreme problem because archers don't have math skillsofts to correct their aim on the fly. It'd play hell with aiming. I've done some archery, and it's hard enough to aim in the only gravity I've ever tried it in. If i tried it on the moon the arrow would miss hugely instead of only a bit.

You understand that you don't actually enter this world physically and directly experience interaction with it.

You can simplify missile fire into straight line ranges you know, I mean sure its a revolutionary suggestion since, that's what most games do anyway but some of us live on the edge like that.

EDIT: by a great deal of math, i don't mean for a given point, i mean for all the sections at whatever granularity we feel like simulating

This is hilarious, effectively you say, "If you decide for no reason to do a great deal of math you will be forced by something irrelevant to that decision to do a great deal of math!"

[TarkisFlux]

Why are we getting away from the inverse squared law again? Just keep it, steal the "collission" mechanics from electro-magnetism for like charges (because they function in the same way), and live with the fact that all of your trajectories are now hyperbolic arcs instead of parabolic arcs.

It pretty much means straight line travel through/near the center won't happen and the specifics of trajectories will differ, but it's close enough that a large number of your general assumptions regarding trajectories will carry over. More importantly, most player assumptions will carry over. It also fixes the problem of gravity spontaneously flipping on you, because it just doesn't happen unless you fly through the exact center (which is technically impossible). It'll change gradually, and it'll change more quickly the closer you are to the center, but if it requires more energy than people can muster to fly close to the center it'll never change faster than people can adapt to it.

Actually, that's indirectly an extreme problem because archers don't have math skillsofts to correct their aim on the fly. It'd play hell with aiming. I've done some archery, and it's hard enough to aim in the only gravity I've ever tried it in. If i tried it on the moon the arrow would miss hugely instead of only a bit.

If you grew up on the moon and practiced there you'd be a good shot there. If you practiced in a hollow world you'd be a good shot there. If you move to a place where your base assumptions fail, you're going to suck for a while, but there's no reason to assume that peope who grow up in an alternate environment haven't figured how to work with/around it.

[Maxus]

If you move to a place where your base assumptions fail, you're going to suck for a while, but there's no reason to assume that peope who grow up in an alternate environment haven't figured how to work with/around it.

Except we, as players, would have to figure out how to work with it, too.

[name_here]

See, if airships aren't universal, then places where the inverse square law lowers the gravity act very much like the moon for most people, and it'd take lots and lots of practice at each distinct section to get accurate with it, which is only fesable if you have lots of time to train with using bows and either own an airship or are in a well-funded bow corps.

Actually, it's most likely most "navies" will say, "fuck it, training people in the gravity levels is too difficult, let's stick with melee weapons which work mostly the same."

I mean, we're familiar with the concept of the low lunar gravity, but that doesn't mean i can use a bow on the moon effectively. Well-trained archers in the setting won't have problems, but other people won't have a gut feeling for how the local gravity effects their shots.

[PhoneLobster]

Except we, as players, would have to figure out how to work with it, too.

There is a thing called a character, it is different to a player, I suspect you need to work on understanding that difference.

[Maxus]

Except we, as players, would have to figure out how to work with it, too.

There is a thing called a character, it is different to a player, I suspect you need to work on understanding that difference.

Don't give me that shit you patronizing jackass.

I mean someone, on planet Earth, would have to sit down and figure out exactly what differences in projectile trajectory there would be in any given situations that will pop up, so they could model that in the game. And then the players would also have to have a passing familiarity with the various results, so they could know when the hell the characters have a chance of hitting someone and when they wouldn't.

[CatharzGodfoot]

That's not a bug. That's a feature.

It's also a great deal of math, which basically has to be done beforehand. However, at least you admit that it shows up, which means we can discuss whether we like that instead of whether that is precisely the same as some islands which fly.

A "weird pattern" such as a stretched ballistic arc? Not a problem.

Actually, that's indirectly an extreme problem because archers don't have math skillsofts to correct their aim on the fly. It'd play hell with aiming. I've done some archery, and it's hard enough to aim in the only gravity I've ever tried it in. If i tried it on the moon the arrow would miss hugely instead of only a bit.

But in the system i mention you'd actually have an even weirder pattern, because the arc isn't really an arc but rather some sort of squiggle, because "gravity" inverts by the high point of the arc. The problem is worse but also localized, with normal style gravity the problem is spread out but only shows up as screwing with accuracy instead of making attacks beyond a certain range totally impossible with projectiles that have mass.

EDIT: by a great deal of math, i don't mean for a given point, i mean for all the sections at whatever granularity we feel like simulating

If you're near the center of the planet, your situation is analogous to being near to orbiting above the world. The difference is, a gravity well surrounds you on all sides, rather than just one.

If you're at the inner surface, shooting an arrow works just the same as it normally would, with the following differences (that depend on scale):

If you shoot straight 'up', the arrow does one of three things. Either it goes straight up and comes back down, or its velocity is such that it hits what would be the 'top' of its arc at the center of the world (and stays there), or it's at escape velocity and makes it through the center and starts accelerating down towards the exact opposite side of the planet ("straight line travel").

If you shoot an arrow at an angle of less than 90 degrees, it will travel in a curve. The acceleration of gravity will change depending on altitude, just as it does in real life. The direction of the acceleration will also change, but it will be in a continuous fashion; it won't 'flip'. The result is a smooth curve. It will be distorted, but it won't 'squiggle' (unlike powered flight).

[PhoneLobster]

I mean someone, on planet Earth, would have to sit down and figure out exactly what differences in projectile trajectory there would be in any given situations that will pop up, so they could model that in the game.

No, because missile fire in these games is almost always a basic linear simplification. We don't plot missile arcs in regular game worlds adjusting for the curvature of the earth, why the hell would we plot them in hollow worlds?

The answer? Only to manufacture entirely fabricated arguments against using hollow worlds.

It's the "if you choose to use lots of maths then hollow worlds force you to use lots of maths" argument.

[TarkisFlux]

I thought I covered that already earlier in the post Maxus... Most of your intuitions as a player can be carried over assuming we have an earth sized (surface wise) hollow world. If that assumption is bad then lots of things could actually be different enough to invalidate expectations.

Over short distances, there is no change. Seriously. Just like we can treat local earth as flat and gravity as constant for archery and shit, you can do the same thing in a hollow world (unless it's a really tiny hollow world). Change for players? Zero.

Over long distances things are different, but not in ways that matter. Instead of your ICBMs following a a parabolic arc they follow a hyperbolic arc, and the differences are really minor. Since I don't know any players who actually sit down and figure out the trajectory of their ICBMs and account for rotation and other stuff, I don't see this as a serious complaint. Most people would just push a button or finish the spell because the setting already has those assumptions built into it and deals with it for you. Change for players? Zero.

Elevation changes are going to give changes in gravity similar in magnitude (probably a bit stronger actually) to what we feel on earth from our elevation changes. They're not really significant until you get away rather far from the surface though. If you want to go from an earth like grav zone to a moon like grav zone (about 1/6 G if I remember right) you need to move 2.45 times farther away from the center, cancel out 5/6 of the anti-mass or whatever at the center by putting regular mass between you and it, or some combination of the two. It's possible, and it would affect trajectories significantly, but it's not going to happen in a game played on or near the 'surface'. Anywhere it does occur may as well be another plane for all the access you're likely to have to it. Change for players? Potentially zero...

Increasing gravity seems like it would be more common, and there are a few thing you would need to adapt to. Gravity is going to be pushing you towards the ground harder the higher up you are, so things might get 'heavier' as you leave the ground behind, but you can model that as a maximum flight 'elevation' or even give players numbers to work with if you really care. Depending on your elevation limits, ship to ship archery might be impractical, but ship to ship cannon fire or spell hurling can be workable with sufficient motive force. Whether those are a bug or a feature of the setting is up to you I guess.

The fact that gravity pushes harder the higher you are also means that you achieve terminal velocity faster, which doesn't matter since it's already fair to assume that any falls we care about happen in a single round. Falling at a higher elevation would hurt more, but since it's comparable to how falling at a higher elevation on earth should hurt less (the effect of which is ultimately negligable), it's not a real concern.

[name_here]

Everything you said is true near the surface.

Since i am talking about away from the surface, as shown in the paint image higher up, the qualfiers come in.

[PhoneLobster]

Everything you said is true near the surface.

Since i am talking about away from the surface, as shown in the paint image higher up, the qualfiers come in.

So if you allow characters to fly or launch objects to what would be an equivalent of near orbital altitudes outside of the atmosphere in a conventional world, THEN you MIGHT need some special rules to cover that if you wanted a great deal of needlessly detailed simulation of something that you made up in the first place and could readily change on a whim.

Just like you might need some special rules if you allowed characters to fly or launch objects into near orbital outside of atmosphere altitudes in a fictional conventional world. If you wanted a great deal of needless detailed simulation of something that you made up in the first place and could readily change on a whim.

Stop the presses! It's another same situation different conclusion argument! Do you guys have anything else?

[name_here]

The argument that we only want hollow worlds if you can do the straight-line trick.

[CatharzGodfoot]

Everything you said is true near the surface.

Since i am talking about away from the surface, as shown in the paint image higher up, the qualfiers come in.

I don't think I missed anything in my description.

To recap:
At the center, you're at the top of a 'gravity hill'. All directions are down.
At the edges, it's effectively the same as being on the surface of a normal planet.
Half way up, you feel slightly less gravity than at the edge (remember, inverse square). The direction of gravity changes over 'horizontal' distance, but in a continuous and gradual fashion; the result is slightly distorted trajectories.


I haven't thought much about the 'gravity increases as you get higher' idea, but it should be similarly conceptually simple, if more alien.