Large cylinders

Is there any low-prim workaround for any kind of cylinder that is wider than 10m? I know there are some high-prim solutions involving big ol' plates that connect, but is there a simpler method, for say, vehicles?

Yeah, I'm interested in this too. I'm trying to make a tree that is appreciably large enough to get inside and have breathing room.

The only way I can think of is using squashed and cut cylinder segments, which sucks and is bumpy.

I'll drop some large cylinders on both your profiles. If you have any questions on them, let me know.

Many thanks!

One Word...

Luskwood

chosen, if you don't mind, i'd love to see your examples too

10 meters isnt enough for monster truck wheels?

I dropped 3 objects on each of your profiles, one called "30+ Meter Circle" (20 prims), one called "30+ Meter Circle, Seamless" (40 prims), and one called "30+ Meter Circle, 12 prims". Feel free to take them apart, and see how they're made.

These are relatively low prim for their size, especially the 12-prim version, which is about as low as you're gonna get, but none of them are suitable for standard vehicles since they're too big to be one link set. For vehicles, the biggest I've been able to go is about 23 meters with the 12-prim circle. Havok 2 is right around the corner though, so I'm hopeful that giant flying saucers will become a possibility soon.

Hope this helps.

Ooh Chosen, could you drop some on me too? Thanks, you are so clever.

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A proud member of PIC = Pudding Inner Core
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If you would be so kind, drop one on my head too?

Wow...that would seriously come in handy...care to spread the prim love a little more?

cud i have these large cylinder also? drop to Ywoski Khan not severe

Chosen, do you have a script that helped you make these or did you just craft them by hand? I am needing to build a large bridge that is an arc which needs to be very wide (like 100 meters) between the two bridge bases, and about 25 meters high at the highest point of the arc. Are your cylinder sections that big?

To answer your question, I did them by hand with some simple math and a little bit of good old fashioned eyeballing. The technique is fairly simple. Here's how I do it:

Chosen's 7 Steps to a Giant Circle
It should take you about 30 minutes to do this the first time, and then you can take the circle into inventory. After that, it will take you all of a second or two to rez it each time you need to make additional cicles.

1. Lay out a circle texture across a large plane made of cubes. Use basic math to do the layout. If you want a hundred-meter circle, use a 10 x 10 configuration of 10M cubes. Set the texture repeates to 0.100 per face in both directions, and offset each one in increasing incriments of 0.100, starting +/-0.450 on each edge and +/-0.050 on the middle most prims. This way, the whole thing will lay out to form one complete image. (See Figure 1)

2. Hollow a 10M cylinder, and cut it down to 30% to make an arc. If you use any more than 30%, the edges will curve too much. I usually go with .35 to .65 on the cuts so that I'm working with the middle portion of the arc. This makes it easiest to manipulate.

3. Place the arc on the edge of the circle, and squash it until it's tangent at every point. For the size we're going for, 0.62 on X is about right if Y is 10. (See Figure 2)

4. Now for the tricky part. Duplicate the arc, and line up the copy by rotating it and moving it so that its edge is flush with the edge of the first piece, and so that it is tangent with the circle at all points. It should come out to be offset from the original by 9 degrees rotation, and by 7.946M on X and 0.6255M on Y (Yes, you can move things by more than 3 decimal places. Even though you can only see 3, you can type in well more than that.) (See Figure 3)

By the way, if you're wondering where I got the location numbers from, no, I'm not a trigonometry wiz. I laid the pieces by eye, moved the camera in as close as possible, and then increased or decreased the numbers in tiny increments until everything was flush. If you're better at trig than I am, I'm sure it's possible to just do the math and make the whole thing work automatically without having to eyeball anything.

5. Since we now know that 9 degrees is the magic number, we also know that it's gonna take 40 pieces to complete the circle (9 x 40 = 360 degrees). The good news, is we don't have to do anything 40 times. All we need to do is complete 1/4 of the circle, and then duplicate that quarter 3 more times. In other words, we only have 8 more arc segments to line up for a total of 10 in this quater, and then we're almost done. So, duplicate the arc 8 more times, and line them up. The rotation value for each one is obviously pretty easy, just increase each one 9 degrees. For location, again you can do the trig or you can just eyeball it like I do. (See Figure 4)

6. In figure 4, we can see that the circle is coming out a little too big. This is no big deal. It's just one of the effects of not doing the trig. Not to worry, it's simple enough to shrink the whole thing to the right size. The arc is still a quarter circle right now. It's just a quarter of a bigger circle than we wanted. Just select the whole thing and shrink it down a bit until it matches the circle again. Just make sure you slelect the original arc last, so that the whole shrinks in an easily controlable direction. It's also a good idea to take this opportunity to link the arcs as efficiently as possible. This will make things much easier for the final step. In this case, 2 groups of 5 works well. (See Figure 5)

7. Okay, we're almost done. All that remains is to duplicate the 1/4 circle 3 times, and line up the quarters to form a seamless whole. (See Figure 6)

8. (OPTIONAL) Cutting the cylinders leaves behind V-shaped crevaces on the inside of the circle where the edges of the arcs meet. To eliminate them, fill each one in with a triangular prim. I recommend using prisms since we're dealing with isosceles triangles, but cubes with top-size zero work just as well.

Here are Figures 6 & 7. By the way, the spaces that appear in Figure 6 are not really there. They seem to be an issue with my video card. As you can plainly see in Figure 7, the spaces disappear when the camera is close. They only appear when viewing the inside of the circle from a great distance. I'm assuming this is because the arcs only touch at one point, and when the camera gets too far away, that point becomes too small to draw so my video card decides to ignore it.

OMG!!! Chosen, Thank you SO MUCH for your very thorough reply!! Holy Cow!! That was nice of you!! The info you provided should be extremely helpful to everyone.

pretty nifty Chosen!

Just because Chosen Few is pointedly not mentioning it (shame), people should know that there is another way to make large cylinders that many people find easier. The resulting cylinder if made with enough prims actualy aproximates a circular shape *closer* than Chosens chosen method.

Cadroe Murphy makes a set of *free* tools for creating larer than 10m curved shapes. They are faster to use, and many find them decidedly easier to use since the process is automated and one only has to enter in the radius and number of prims and type "res."

The secondary advantage is that they also make spheres, tori, round platforms, spiral stairways etc. all of almost any size you want. I would especially recommend this for the person building the bridge or any geometric shapes, although those building tree trunks might want to stick with Chosen's more organic and irregularly shaped cylinders.

The tools are available from Cadroe Murphy, I think they are just in his backyard the lastt I checked. Alternatively I can drop copies on anyone who wants them.

These tools are fast becoming a standard IMO and the only reason I am posting is to offer people an alternative that Chosen sees fit to not mention, perhaps in favour of promoting his own solution.

Previous to the existence of these tools, Chosen's method was in fact the only way to do this and it *is* ingenious. However there are alternative (many think better) ways to do it now and if you are serious about geometry and making large rounded forms you owe it to yourself to check them out.

Note to Chosen:

I dont want to get into another flame war about this and I will of course AR you if you insult me over mentioning this again. I am ONLY POSTING THIS TO HELP PEOPLE OUT WITH ALTERNATIVE INFORMATION, so try not to take it so personal this time please.

Note to others:

If this is like the last thread on this topic, Chosen will likely follow with all kinds of information on how I am wrong and his way is better etc. but you may wish to ask yourself who has the agenda here. Besides how could it hurt to look at both solutions?

This is my first, last, and only post on the matter for INFORMATION ONLY.

Flame on Chosen!
(or not, let's try "not" this time)

To Champie, Chazj, April, Angus, Sophia, Severe, Forseti, Gleeb, Hobonicus, and anyone I forgot, you're most welcome. I hope the information was helpful.


As for the other post, just as I've said before, Cadroe's tool is great, but like all tools and all methods, it has its place. I didn't mention it because the original poster had asked specifically for a low-prim solution, and had stated that he didn't want an answer that included the use of "plates". I took the word "plates" to mean flat sides. Cadroe's tool is what I would consider a high-prim solution since it only deals in cubes, and it takes a great many cubes to make a convincing cylinder. To me that sounded exactly like what the original poseter did not want. That's all. Like I said, it's a great tool, but it's not what was asked for in this particular instance.

I'm still extremely confused as to why you refer to perfect circles as "irregular" shapes, but oh well. I have no desire to get into that discussion again. Beleive whatever you want to believe.

Yeah, that's pretty much what I meant. I had seen the "using cubes" tool on spheres and cylinders, but those used too many prims for my tastes.

Hi, can you also give me a set of large prims? I am trying to make a large flying saucer spaceship.

Thanks!

Could I snag a copy of both too?

What an enormous amount of work you went through to make these. Most impressive,

I have a project in mind (non-commercial) that would benefit from these giant circles and would like to get copies please and would gladly make a donation for a set of them modifiable and copyable etc thanks

What benefit does one derive from using non-circular elliptical arcs to make a giant circle with as compared to flat pieces?

You can use boxes with the top size adusted such that they make perfectly fitted regular polygons, how can you do better than that as an approximation to a circle?

Here's a picture.

sue I'm sure the script your mentioning is a great tool i have never heard of it and if ya have a copy i like to play with it. but respectfully i just read this whole thread and that's not what the original poster wanted. and some times its fun and educational to do things like this by hand cause you get to learn more about how the building tools work. if we just handed every one a script that built every thing for us building in second life would get rather boring. some of my most fun times in second life have been figuring out how to make something look like i wanted it to by just manipulating the prims.

hugs crucial