Larger Perfect Spheres and Circles

Well, it's probably common sense that no one can build a perfect sphere or circle, ellipse or oval, beyond a 10x10x10 axis. And if someone DOES know how, then I want to know. But, I've been going over mathematical connotations, I've been trying to figure out, how would someone build a spherical or elliptical type unit that is larger than the said volume? The reason is that I have been trying to develop a design for a star-trek like ship, with an actual spherical bridge.

And this is the conclusion I've gotten to. According to the Radius of Curvature and the Tangential slope of the radius of curvature, it would be possible to get close to a spherical shape, should one use textures to a very high precision, to account for descrepencies in the actual shape. That is, to say, when I am approaching metallic overlaps on the outside of my sphere, each one would be very small and provide small segmentations where they connect to one another, but do not quite join unison. And since textures cannot create an artificial curve without taking part of the object away by turning it invisible.. we cannot have that small visible segmentation removed. Not to mention taking a large number of small strips.. that takes a lot of prims.

The other aspect that I considered would be to have a Large 10x10 squares that I would place textures on, with a texture being made precisely for each 10x10 piece.. The textures would modify the box to appear to be a curved surface. BUT, as we all know, a 10x10 block is a 10x10 block, and that would create a surface that, while being invisible, would still make a poor avatar smack into it if they came too close.

Of course, the star-trek idea would mean that a shield could be placed around the craft, but then we have the same problem as before, as the shield would have to be curved.

The one alternative that I have thought of while trying to do this, would be to make the inner plates underneath of a texturized surface. Since the plates would be inside of the textured square, they wouldn't be noticable unless you FLEW into the textured square. And they could be arranged to give the textured square some sort of quasi-realistic surface, while the textured square itself would be phantom. But the problem with that? IT would take a LOT of prims.



So.. before I go and try to calculate the exacts of the strip things, I wanted to post this to ask around and see if there was anything that I had missed, as well as to see if there would be a place I could build the said sphere, as well as see if there aren't some sort of plans of Linden Lab's to create sphere or arc components that one could make a larger curved surface out of.

You would probably need to make a geodesic dome, with triangular facets. You will still run into problems there, however, in that prims can only be linked over a distance of 30 meters. So while a geodesic might get you to a 20 to 30 Meter diameter, it won't go farther without being seperate, unlinked things.

A geodesic will require a LOT of prims. And texturing the faces of a triangle can involve coping with some strange distortions.

If this is to be a vehicle, there are also limits on how many prims you can use at once, including any passengers as one count per seated avatar.

Unless I use a non-physical vehicle script.. then I can have over 200 parts per vehicle. But still, that would take a LOT of work.

On the other hand, I have to ask you, because that is a good idea. Do you mean just using flat triangles to create a dome-like shape? Or cutting out a sphere into a triangular segments, and then piecing those together along with other segments? And how would that apply to a cylinder?

Also, the smaller the triangles, the less area the objects will link over, while the larger the area, the less dome-like it will be.

The best way I know of to make very large geometric shapes is Cadroe Murphy's Shape Maker. A great tool that will build very large rings, spheres, and torus out of many prims.

It is a free tool - but is sometimes hard to find in-world. You can get a copy at the Prim Twisters' Workshop in Bembecia.
http://slurl.com/secondlife/Bembecia/104/193/110/

Thank you Vlad! I'll have to seek that tool!


I was suggesting a true Geodesic dome, made of flat triangles. A cylander could be aproximated with flat strips arranged mathematicly for the appropriate angles, and aligned carefully by eye.

See this site for info on geodesic domes. You may want to do a google search to get info on designing one.

I have a geodesic dome maker and a few geodesic spheres/domes in inventory. Depending on what the project is I might be convinced to part with one or create one to spec.

Nand Nerd makes massive multi-prim spheres via a script. He'll gladly show you I'm sure if you IM him when he's on.

The possibilities of this are great for even small things, like arches, curved pathways, decks, etc. Even for iterating objects along another maybe. Can't wait to see that Cadroe Murphy tool.

shapemaker is a great building tool. but please use it with care. once i left one in a sandbox sim and some one give it a commend(apperntly anyone in the range that knows its channel can control it) to build a huge sphare that was enclosing the entire sim. 4 hours later i got messages from ppl that my shapemaker was still generating prims and making the sphare. it was going to crash the sim. i had to come back in and clean up the mess.

Lol. Thanks for the tips. I read that thing on the geometric dome and decided to go for a geometric design. After loading up autocad and making a rough figure, I was able to build a 224 prim dome that has 28 sides, and you really can't tell the difference between it and a circle. It is 14m in radius, and it has 4 floors to it.
But.. I still have to design something for my ship.


I looked at Nand Nerd's set, and it reminds me that I have to show him the dome I made. I think he'd probably like to make a script to use triangles instead of his rectangles.

On the other hand, as much as I would love to see the shapemaker in action, I wasn't able to get the darned thing to work. So.. if anyone knows how to make it tick, I dunno. Maybe I just got a bad copy.

Sorry for taking so long to get back to you on all of this.
And.. thanks for all the ideas.

At least now that we have statistics, I can build SL programs to do my statistics homework for me, lol.

Ciao, and hasta luego muchachos, muchachas, y muchachichochas.

Areth, I very much look forward to seeing your sphere and I do indeed intend to script a rezzer which uses triangular elements instead of my quadrilaterals (cubes with top size). At the moment I lack the mental energy to work out how to calculate the neccesary values for a squashed sphere, perhaps I should kick something up in AutoCAD too, see if that works better than my shoddy pencil & paper doodles.

mmm, Pi.

nand

I have used Blender and the OBJ-to-Prim script to create a very nice geodesic dome with a radius of 15 M. This could be expanded to be a full sphere quite easily. The half-sphere dome comes to 40 prims (42 after adding doors and an opacity switch). A full sphere would require 80 prims.

I have one in Scotopteryx at 500m above my airport.
http://slurl.com/secondlife/Scotopteryx/191/152/501/

I also have one for sale on slexchange (see picture here> http://slexchange.com/modules/Marketplace/Images/a8ef3ceb820b09b5bdb178e4b8b340ee.jpeg)

If anyone is interested I could give them a demo of how it is rezzed. It does take a good 30 seconds to build itself so it would not be practical as a raisable sheild unless you rezzed linked parts of a pre-generated dome.

I picked up a copy of the shapemaker tool, and I am also unable to get it to work. Any tips from experienced users would be appreciated. The most I have managed to get it to do so far was to make 24 triangular prims, stacked on top of the tool like stacked cups.

Incidentally, it appears the maker of the shapemaker tool has modified it so it listens only to the owner now.

You're not having trouble with Shapemaker's sphere making functions, are you? Because I've made a few spheres and had so little trouble I wouldn't even know what sorts of tips to give, though I might be able to help if you're more specific about what you're doing.

(And if it's the tori and rings that are giving you problems, I don't blame you, though I can't help. I haven't touched those capabilities; too much work to understand when I've not had a use for them.)

I've had your problem before - resetting the script usually clears the problem. In the unlikely event that the reset is not successful, get a new copy of the ShapeMaker from your inventory and delete the 'broken' one.

Once you have reset the script or rezzed a new ShapeMaker, delete any of the old triangular shapes above the ShapeMaker (you said that they are stacked above it) - you need to delete them one-by-one or just select all of them and delete.

Specify your parameters - sides and radius (maybe zoffset for larger circles). Leave the other parameters alone for now. When you're ready to make a sphere, say "/12 sphere" and watch it go. The key is to list your shape's parameters before you create the shape.

I had problems with the zoffset parameter - I made a couple of *big* circles and ended up with half of the prims in the gound even though I used a zoffset of 100. I eventaully raised the shapemaker off the ground to avoid further problems and was able to create a rather large circle having 20 sides (lots of prims).

Rings are a little different in that you use another command to create the ring and you have a few more capabilities (like deleting the ring with one command). I cannot log into SL from where I am now but the notecard provides enough instructions. Just read the notecard carefuly.

Once you wrap your head around it, you'll find the ShapeMaker easy to work with.

I think the zoffset may have a limit of around 20 meters or so. I tried setting it to 30 once, and my sphere got built near the ground; 20 worked fine on the same sphere, though.

So far, Shapemaker has failed to do anything at all for me. Does it only accept one command at a time, with the last being what you want to rez?

In other words, I have been trying :

/12 sides 12 radius 10 thickness 0.25 arcsides 6 sphere

That gets met with no reply at all from the tool.

Should I instead be splitting each step into it's own spoken command? :

/12 sides 12
/12 radius 10
/12 thickness 0.25
/12 arcsides 6
/12 sphere

And then it will make the shere? Is that it?

When I had just reset the script, and was flying right next to the tool, I said "/12 sphere", and it did actually reply that a sphere had been made. But nothing was created. Probably because it had no data for # of sides or radius?

I think that may be your problem, actually! I've only ever used one command at a time, and it's worked.

Try putting each command on one line, and see if that works?

Yes...one command per line..then finish with /12 sphere. It works...just be patient