And now for something completely different...

[rthorvald]

it has been a while but the ringworld was built by a pak protector,pish-tok ??? spelling.

Some Pak, anyway. I remember feeling cheated a bit by that, it removed too much of the mystery.

- rthorvald

[John Van Vliet]

--- edit ---

[rthorvald]

The shadowsquares don?t cast shadows,

i would have thought that eclipse shadows would have done it

That only works if the objects are orbiting each other. The shadowsquares and the landstrip are both orbiting the star, independently. There is no way to get the squares to orbit the strip and maintain the day/night cycle...

- rthorvald

[MKruer]

I havent tried this, but it might work. create a dummy object. center it on the star, then add the ring and shadowsquares as sub - objects. I believe that you can have multiple sub objects cast shadows

[rthorvald]

I havent tried this, but it might work. create a dummy object. center it on the star, then add the ring and shadowsquares as sub - objects. I believe that you can have multiple sub objects cast shadows

I have done that. In principle, it is the correct thing to do, but Celestia becomes very erratic with such a configuration. It does not like a dummy object orbiting (enclosing) the star, several orders of magnitude larger than the star. The children objects is rendered unpredictably and incorrectly... So, no go.

I have tried a _lot_ of creative alternatives. I have actually managed to wrap an atmosphere to the ring, but functioning shadows must still be faked. I am getting there, though. Still not as good as the real thing, but i am approaching something i can work with. An example, from "ground level":


- rthorvald

[t00fri]

Runar,

from it's morphology and isolated location, this strongly peaked Fist of God mountain can only be be a volcano ( I am guessing, don't know the story). But how could I physically understand volcanism to arise on a "ringworld". It's all synthetic anyway, I suppose? Built in "floor heating"?

Fridger

[John Van Vliet]

--- edit ---

[rthorvald]

I havent tried this, but it might work. create a dummy object. center it on the star, then add the ring and shadowsquares as sub - objects. I believe that you can have multiple sub objects cast shadows

Your post caused me to reevaluate the idea, and do some more testing with it. It turns out i can get it to work by making the dummy object very tiny - which i didn?t try because in older versions of Celestia, that would cause all kinds of weird behaviour.

So, i now have real shadows working! However, the results are unexpected. The shadows cast by the shadowsquares work, but night aren?t visible from afar - you must be relatively close to the Ring Floor to see it. More importantly, it seems the shadows on the Floor are moving and overlapping each other in a strange pattern.

I am no astronomer, but that seems wrong to me. Can anyone with some knowledge of orbital mechanics and how light behaves please give an opinion on this? Is this really how such a system would work, or is it a buggy Celestia?

It is impossible to show this with screenshots as it is an animated effect, so i have prepared a small pack (1,8 mb) that demonstrates this. A CelUrl is enclosed in the pack. It is here:
http://runar.thorvaldsen.net/celestia/t ... d_test.zip

Use a recent (1.6 pre) Celestia from SVN, and make sure to have Eclipse Shadows enabled.

Any input here is much appreciated.

- rthorvald

[rthorvald]

So, real shadows:

Seen from the ground:


The same spot, seen from above:



- rthorvald

[BobHegwood]

Way cool here, Runar...
Yer a certified genius, son.

[rthorvald]

Way cool here, Runar...
Yer a certified genius, son.

Thank you for the kind words, Bob...

It seems the shadow problem is solved, but there are more issues. Here?s a wide-angle shot -- an overview from the ground:


... The next challenge is to get the atmosphere to obscure the Rim Walls. They are so far away, they ought to be completely invisible from the center of the ocean. This looks unreal. I am playing with the mie parameters, but it behaves very strangely on this scale, with atmospheres that are 99% oblate... I might need to fake it, by adding semitransparent cloudmaps to the walls themselves...

Note that i am not doing all these detail for the entire ring. Everything is concentrated in about 1 degree of arc, whith oversimplifyed approximations for the rest. Else, the scenario would be impossible to run on a home computer. So, all the effects is at the Great Ocean - but then, all the action in the book took place there, so that does not matter much.

- rthorvald

[Rassilon]

this completely blows me away... I cant wait to see the finished product in action!

[MKruer]

This so makes me want to start working on my Blue Venus Parasol & Reflector (Mega Structures) viewtopic.php?f=6&t=11660&st=0&sk=t&sd=a if i can only figure out a way to make a faceted hexagonal dish

[rthorvald]

I am taking a break from the ring, and doing some modelling on the various spacecraft in the story. Here?s one of the "air bikes" (the human model is a prop from a freeware site):



- rthorvald

[Guckytos]

I am taking a break from the ring, and doing some modelling on the various spacecraft in the story. Here?s one of the "air bikes" (the human model is a prop from a freeware site):

- rthorvald

Hehehe, looks flashy this bike. But I wouldn't want to ride this one. I fear the big engine exhaust nozzle (and the probably resulting forces at full throttle).

But as far as I remember the books, the things were described as 2 balls with a kind of motorcycle frame between them. And a nice and cozy chair, with a long back, where you could rest your head.

Apart from that keep up the excellent work. Can't wait until it is finished.

Regards,

Guckytos

[John Van Vliet]

--- edit ---

[rthorvald]

But as far as I remember the books, the things were described as 2 balls with a kind of motorcycle frame between them. And a nice and cozy chair, with a long back, where you could rest your head.

Yes, i started out with two spheres. But could not get it to look like anything that could fly... So you can still see where it comes from i think, but it looks more like a car than a bike now! We?ll see, perhaps i should accentuate the spheres more.

It does have four engines, though. But what do a "reactionless" drive look like, anyway...

- rthorvald

[Guckytos]

But as far as I remember the books, the things were described as 2 balls with a kind of motorcycle frame between them. And a nice and cozy chair, with a long back, where you could rest your head.

Yes, i started out with two spheres. But could not get it to look like anything that could fly... So you can still see where it comes from i think, but it looks more like a car than a bike now! We?ll see, perhaps i should accentuate the spheres more.

It does have four engines, though. But what do a "reactionless" drive look like, anyway...

- rthorvald

Hmm, I think a reactionless drive could look like anything, since it won't need an opening, or would it?

How about adding two short wings to each sphere, with a long silver cylinder in the middle of the wing? The cylinder could represent the drive.

And you could perhaps shape the front sphere with a bit of a cone. So one knows where the front should be.

Guckytos

[Reiko]

But as far as I remember the books, the things were described as 2 balls with a kind of motorcycle frame between them. And a nice and cozy chair, with a long back, where you could rest your head.

Yes, i started out with two spheres. But could not get it to look like anything that could fly... So you can still see where it comes from i think, but it looks more like a car than a bike now! We?ll see, perhaps i should accentuate the spheres more.

It does have four engines, though. But what do a "reactionless" drive look like, anyway...

- rthorvald

Nothing in the book was meant to look like anything that could fly. The ship they used was called the Lying Bastard by the main character simply because it looked less than what it was.

[rthorvald]

Hmm, I think a reactionless drive could look like anything, since it won't need an opening, or would it?

How about adding two short wings to each sphere, with a long silver cylinder in the middle of the wing? The cylinder could represent the drive.

I decided to just go one step back, where the spheres are more prominent. Cockpit is the same - this time with our insane two-headed alien occupying it:


A bit closer:

Nothing in the book was meant to look like anything that could fly

That does not matter - in practice, things must look reasonably plausible, or the scenario will fell wrong. But i have made a reasonable compromize here. Apart from Nessus, which will look implausible no matter what

- rthorvald