Huge Prims - what are the tricks?

Hi everyone,

Id like to make a giant sphere on my island, using a huge prim,
but I dont want it to be phantom, yet Id like it to be hollow...

anybody have some tricks on using these? Currently, if I make it hollow, I cant walk into the hollow area... unless I turn phantom on...
can someone help?

Cheers

Megaprims were created through a hack, and don't behave normally when rezzed in world.

What you see is what you get. I don't believe there was ever a workaround for the hollow/phantom issue.

Perhaps you can script it with a collision detection that would bounce people away whenever they touch it, in essence creating a faux barrier.

Someone wrote a script to rez big geodesics. Seems to be the easiest way to generate large spheres in world that I've seen. But maybe this way you can just make some of the faces of the geodesic phantom or delete them entirely, or script them into doors, or whatever.

Thanks for the reply JT Dagger, I know of the script you are talking about - it's called ShapeGen .95 and I think there is also a free version in the lsl library.

That script is great - you can create the sphere automatically, as large as you want - the only problem is - its not that pretty. But last night I had an idea of combining it TOGETHER with the Huge Prim - ie: make all of the shape gen's sphere's sides transparent - and then cover it with a phantom huge hollow prim. That way, you get the beauty of the huge prim, (A perfectly round shape) and the boundry of the ugly generated prim.

It just might work...

if anyone has any other ideas... please let me know

hmmm. I didn't think the giant prims were hollow.
In my experience, if I changed them they disappear back into my Lost and Found.
Something about PHYSICS not working with the giant prims...they need to be phantom, apparently, but I stopped trying to make 'em work.

Let us know if this works...it's an excellent idea.

Depends what you're doing, but this is the way I'd make something like you descibe:

Use the giant hollow sphere, but make it phantom. Then add a few big, transparent planes made from cubes to make the floor and any other boundaries you want, remember you can get something that looks close enough without it being perfect. Personally, I reckon this is good practice for any complex object, but in this case it cuts down on physics calculations and the number of prims compared to using a geodesic sphere.

EDIT: Oh, just read your post describing the same thing using shapegen. So, I guess all I've got to say is the bit about approximating only what you need.

Once I got the "Huge Prims" pack.. I was determined to try and find some responsible ways to use them. I did a great deal of work with boxes and cylanders.. but I haven't done much with spheres.

But based on some of my experiences with the cylander, I was determined to find a way to make the sphere work and still be physical.. So I did some experimenting using the 40x40x40 sphere.

dimple the sphere | B: 0.50 | E: 1.0 |
(half a sphere)

path cut. | B:0.80 | E 1.00 |
(1/5th section)

Hollow | 95 |

Now..

Clone 5 times, rotate each as follows:

1. | x: 0.00 | y: 90.00 | z: 0.00 |
2. | x: 270.00 | y: 18.00 | z: 90.00 |
3. | x: 270.00 | y: 306.00 | z: 90.00 |
4. | x: 90.00 | y: 306.00 | z: 270.00 |
5. | x: 90.00 | y: 18.00 | z: 270.00 |

You now have a dome.
Now we need to make the bottom half (assuming you need a sphere.)

Select all 5, and clone again.

6. | x: 0.00 | y: 270.00 | z: 0.00 |
7. | x: 90.00 | y: 342.00 | z: 90.00 |
8. | x: 90.00 | y: 54.00 | z: 90.00 |
9. | x: 270.00 | y: 54.00 | z: 270.00 |
10. | x: 270.00 | y: 342.00 | z: 270.00 |

This has been tested to work with the 40x40x40 "Huge Prim" sphere. Your mileage may vary.

/8/02/155838/1.html

Hopefully you've seen some of the other threads that cover similar material.

Hi There Jt Dagger,

Thanks a million for posting this trick. I tried your solution and, interestingly enough, it works for 40x40x40, but not for the 50x50x50

I am pretty happy about the 50 but the 50 would be great too!

let me know if you tested your technique on the bigger prims

cheers!

I'm glad you're making progress, though I can hardly take credit for the technique - the script-fu and math-fu of other residents is very strong - mine? well i'm noob. I haven't tried it on larger prims but other people reportedly have. I've done some minor experiments with shapegen, but its not much. I've had some success with making things in Blender and importing them into SL as discussed in some other threads - I think it's more flexible than Shapegen. Create the mesh in Blender, import to SL - works very well. An icosahedron generated in Blender, translated to SL prim-triangles, imported, then rezzed, makes a very nice dome. Though I haven't tried making gigantic ones yet.

This material is pretty well covered in other recent threads imo, we should probably let this one fall to the bottom of the stack.

A discussion about geodesic spheres:
/8/02/155838/1.html

I poked at the 50x sphere, and I regret to say that no, this trick won't work with the 50. But the fact that it will work with the 40 is still pretty cool (in my opinion). You could do something with a 40, that was transparent, and a 50 that was phantom.

There is SOMETHING you could do. you could make a fence. assuming you want to make a dome... you dimple up to 50, and down to let's say 60. Then you make small physical sections. (let's say 10). The hollowed sections will have a small "impassable barrier" on the inside face.. but this is minor. Then, you make a phantom CAP dimpled 0.60 to 1.0.

I dunno. these things are buggy, and use a really old physics model.

The fact we can use the 40 to make domes.. makes me happy enough.

Winter,
The trick which you are seeing is you got the pieces under the 20x20x20 bounding box limit of the Havok engine. Once the prim goes over that size it no longer collides correctly. I built my entire shop out of large prims. think this was 82 prims and cut it down to 60 while at the same time added more detail.
Other things you can do to fake different sized rectangles. Change the prim to a sphere Dimple it all the way to one end. Then Go back to a box. Use the Tapers to "adjust" the size. Good for long stretches of road large walls. Also works with cylinders and triangles. Since these probably will be over the 20x20x20 bounding box size but it is already a box it does not matter. Then you can use a tube and adjust the X and Y Hole size. This also makes the over all size change. Now the big draw back is the Mini-Map which it shows a square on the map bases of a combination of the X and Y size. since you never are really changing those values it will always show up a a big square on the Mini-Map, no matter how small you make it in world.

use this to find the over all size

default
{

    touch_start(integer total_number)
    {
        list bbList = llGetBoundingBox(llGetKey());
        vector corner1 = llList2Vector (bbList,0);
        vector corner2 = llList2Vector (bbList,1);
        vector size = corner2 - corner1;
        llOwnerSay (llList2CSV([size.x, size.y, size.z]));
    }
}

EDIT:
even after getting the object under the 20x20x20 size limit it may still have problems but not as bad. Things change from update to update. to some of these tricks may not work

My favourite has to be the 20x20x60 cylander, and then the 20x20x0.5 box.. turned into a cylander. Hammer that "tree trunk" around a bit, and you can use 1/4 sections. I've really enjoyed being able to make 10m radius rounded corners (on my 30x30 store, and on our 60x80 racetrack.

I tried putting the 40x40x40 sphere to use in building the store.. but it just didn't "call to me".

hey i recently got threatened with bans fomr most sandboxes for using mega prims witch is a shame realy as i could realy use them
would anyone here know and be willing to divulge a few areas whee they can be used?

As long as you don't use the mega prims to interfere with other peoples builds or avatars, most people will look the other way.

Don't mess with the ones bigger than 40m or 60m, those are just *TOO* big to behave stable.

If you experiment and sandboxes with megaprims, go to a skypad first. And clean up after yourself when done.

yeah that's my suggestion too. Go up to about 700m. where noone will see you and few will care. Make yourself a nice 60x60 platform in the sky. Then... on the center of your platform, rez the smaller huge prims. as long as the prims aren't bigger than the platform.. no one should give you any major issues.

Basically.. be considerate. Get the heck away from others. Don't slam them down in other people's builds.. some of them can be huge, and solid on rez.. causing people to start floating for no reason. Use them sparingly. Remember that linking distances still apply.

and definitely clean up.

Also.. check the rules area for your sandbox. Many privately held sandboxes have rules against huge prims. WHile my experiments have shown that in most ways they ARE just big prims (if a little buggy in the "hollow" area).. the "mysterious floating effect" caused by rezzing the 1000m cube... has really not endeared the public to these prims. Since noobs and greifers tend to just pull them out wherever. The minimap goes grey, and everyone starts floating.. it only takes one person to annoy the admins.. and people with power love to make sweeping legislation.

But, it's their land.. and if they say no.. then they mean it. the rules don't HAVE to be fair.

I find, though.. that a good skyplat, and a relatively empty sim, are the best combination in terms of when and where to experiment.

(ps.. there's already a 20x20x.5 prim... makes a great basis for a platform!)

I'm still curious as to the stability of megaprims , effect on sim performance and whether it breaches TOS.

No-one seems to have an official answer and Linden haven't really provided any (other than stating private island usage).

The impression I get is that, the jurys still out on sim performance impact (but probably minimal compared to what a huge number of blinged avatars will do to a sim), and with regards to use, as long as you're not distributing or grieving with them, its ok (even on mainland)

Please correct me if I'm wrong.

One thing that is a bit of a myth though, that all megaprims have poor edge/collision detection. On the 20x20x0.5 prim, i can walk across the whole surface just fine, I don't get any of this 'sinking into the floor' that others report.

There is a script out there for making the Geodesic Sphere.

http://www.slexchange.com/modules.php?name=Marketplace&file=item&ItemID=166472

What is the formula that computes what the diameter or radius will be working backward from a given number of faces at a given size?

A tiny quibble with that product is that it's NOT a geodesic.

Another is that, wow, that's overpriced, given that someone else on the forums posted a link to a free script, that actually produces real geodesics.

Asking a favor, please:

I was wondering if anyone might be willing to send me a megaprim cylinder?

I can't remember the exact dimensions, but roughly 50+ meters across, so that when hollowed out and made phantom, with a pretty interior texture, can completely encircle a small skybox plot. It doesn't seem to be included in the pack that I got.

Pretty please? Thanks so very much in advance!

If you promise to be good with them I'll drop you a full set next time I'm in-world. ;p

Or if you want it now, I think this is the set I picked up.

Thank you -- I'll check it out. It's a different set than the one I picked up, so perhaps that's where it'll be.

And yes, I don't have any crazy plans with them, other than to find the smallest cylinder that will encircle my skybox.

OK, a follow-up question. Having created a 40x40x40 hollow sphere using Winter's method, I would like to build "decks" inside. Is there any simple way to build, say, a 30x30x.2 cylinder? The huge prim cylinders can't be resized.

I, too, am still looking for cylinders large enough to be hollowed out and built inside-of.

(AJ DaSilva was kind enough to send me a set of huge prims, but they were the same ones I had found before, and did not include the large hollowable cylinder I've seen a neighbor use to build inside.)

Yeah, just checked and the prim I thought was that one wasn't. If anyone's got it, could I get a copy too?