Policy on mega prims?

I've come back to SL after a year or so.

When I left, I remember megaprims were something absolutely *NOT* to use outside private sims.

Now they seems to be in wide use. A new neighbour of mine started builidng his home using tons of them (and I'm on mainland).

Can I assume that megaprims are now allowed for general use? No fear of them disappearing or being banned for having crashed a sim?

If you crash a sim, you probally will be banned, if the prim stray off your land it probally will be deleted. Intellegent use of the mega prims are not a problem.

There unfortunately has not been an official policy change so it's still use at your own risk and if they cause problems it's on your head if the Lindens delete them. The fact that they have proliferated is I think partially increased boldness by creators due to lack of enforcement against them and the whole "everyone else is doing it" attitude and also because of increased availability because of a new whole that appeared that allowed a whole new batch of megaprims to be created. The whole has since been fixed but the prims remain.

With the exception of a few "big build" creators who use massive prims for their builds, mostly on private estates but sometimes on mainland, with either willful disregard or with the knowledge (on private sims) of how to use them properly and in limitation I think the common consensus is that 256x256x256 or smaller is the generally safe size to use (I use them occassionally) on builds, again in limitation, and above that is pushing it due to the issues they can cause. Efforts to codify that have been ignored by LL though. Let me know if you want me to dig that up and I'm sure I can find a JIRA issue on that proposal to codify it.

Go for it, in May there was a lapse in viewer control tthat allowed new megaprims to be made, these May ones by various creators aren't tortured to size like the older ones so don't get anywhere near as quirky.
As long as you keep them off sim edges, don't make them physical and keep them on your land then all is good.
I would avoid using the old ones at all now.

Heh... I broke that rule with a few of the new ones without a hitch. =^-^=

I never understand why people say megaprims cause lag, they do the complete opposite. Less prims to transfer over the network means less lag. I have owned the corners of 4 sims before and had megaprims on each corner, each overlapping the other 3 sim corners and there was no problem, it was no different to overlapping any other prim across sim boundaries.

Just don't be silly. If you are rezzing large ones then do it on a sky pad or make sure you have a large plot of land and you do it in the middle. There is no point in using anything over 100m in any direction because you risk people not seeing them with 64m view distance.

The sim collision code keeps a std::map of things that are colliding. As physics frames tick away, entries get aged then removed from the maps. With normal prims, these maps are pretty small. With megaprims in areas that have lots of physical stuff going on, they can cause the maps to grow very large and really increase the cost of aging.

Also, if you have megaprims that aren't world-axis aligned, their bounding boxes get ginormous. I think H4 is better at this that H1 was but they still get really, really big.

Phantom megaprims don't, AFAIK, cause lag. Non-phantom/non-physical ones aren't free but I don't think they're an absolutely horrible idea. Phyisical ones in areas with lots of bullets and stuff can do bad things to the sim..

As for crashing sims, I think H4 got rid of most of those - it's actually sorta hard to crash a sim nowdays.

I just don't like megaprims because the camera goes all screwy when they're around.

Meade, could you explain a litle on that? Would it be where the view cone goes very narrow when the cam is rotated? I have wondered about why that happens and have sort of blamed a 'gimbal' situation.
BR
Ab

I'm not Meade, but here's what I think happens: The camera is trying to not be inside the prim it is focused on, but it isn't smart enough to be aware of hollowed and dimpled prims. What it does in the case you are alt-clicking on a face that is "inside" the prim is move the camera position out of the prim and compensate by zooming in (which also causes stuff to render with lower LOD).

This happens in regular prims too, but is more noticeable with dimpled megaprims. Just dimple the prims so that the side people see is at the edge of the bounding box.

That sounds about right but I think the camera goes weird even on non-dimpled ones. It's sorta like when you alt-click on a spot to focus the camera then zoom in or out, it gets confused by megaprims. Go to any store that uses a megaprim for their floor and cam around - you'll see! (edit: unless I'm totally remembering it wrong)

The "old" Gene Replacement megaprims do this...on one side of many of them, the camera will skid wildly when you ALT+click.

The "new" megaprims, the ones made in that three day period a while back when the loophole was again temporarily open, do not seem to exhibit this behavior. I believe this is because most, if not all of them, are not cut.

Bar that isn't always accurate, less prims are an effect of megaprims but especially close to sim borders (15m I believe) they can cause massive lag and other issues due to the way the servers handle object rezzing and crossing between borders. There are also other issues at play that I don't entirely understand but can have an issue on whether it causes lag or not like whether you're tweaking the prim in the ways available.

Got a source for that? For non-physical prims, mega or not, I'd be a little surprised if it was true..

Not off the top of my head no but I'll search around and see if I can find where I read that. I assumed we were talking about non physical btw since I know they definitely aren't lower lag when physical.

We;;, I use megaprims in my shopping cntre up to 70x30 for floors I think, and haven't noticed any problems, I have 40x40 within 1m of the sim edge too. When I first brougt the land I wrote all the the sim stats down on a notecard, 12 months and a shopping centre later there is very litle difference.

Yeah, but you're good (when you're not being bad)

Oki, thank you for clearifying
BR
Ab

Sightly off topic maybe but does anyone have a view on whether sculpted megaprims may cause viewer instability? I'm using sculpted Research Projects prims to achieve large organic arches for a new castle - very difficult to achieve any other way. It could be coincidence with the recent update but I have been crashing like crazy of late, since way into the build especially when in edit mode - even on sims away from the build. I'm running 1.21.6 on my MacBook Pro. Just trying to figure it out from a non-techy's pov.

Well, with regular prims, the bigger the prim, the more polygons the client has to render. Some people operate under the incorrect assumption that in Second Life a prim cube contains only 12 polygons (2 per face). This is often not the case, however; the polygons increase with prim size for a number of common-sense reasons. If you have a number of giant megaprims within viewing distance filling more area than you could have done with regular prims given the prim limits for your land, you are going to have more polygons to render.

I do not know whether the same rule applies to sculpted prims, which are typically composed of a buttload more polygons than most regular prims. (And yes, even though you may not create your sculpts using polygons, they end up getting rendered in polygonal form in SL.) Sculpted prims can (and do) contribute to client-side lag, even if they don't affect the server too much. If their polygon counts scale with size the way non-sculpted prims do, then yes, this is something to consider.

thanks Wildefire Thinking about it, I actually started crashing when using several megaprims used as in torus form cut down to just it's innermost face.