Building Across SIM boundaries

I own two adjacent lots, each in a different SIM (didn't think to look for that when I bought the second lot). I built connecting platforms in the sky, but tend to fall through the platform when I cross from one SIM to the other.

I experimented with overlapping prims and such and on occasion make it over unscathed one way, but fall through on the return trip. There must be a set of rules that governs this. I've been to other places where they even have signs warning of the SIM transition, but nothing bad happens when you cross.

Any ideas?

You need overlap from both directions. In other words, make sure a prim from Sim A extends into Sim B, and one from Sim B extends into Sim A, and that the two overlap each other in both sims. The entire transition needs to be double-primmed from both sides, or you'll fall through when coming from one direction or the other.

Also, it can be a good idea to put a second set of double prims just below the first, as a back up. If you do manage to fall through the first set, the second set should catch you.

1: You can't share prim count from one side to the other. What is in one sim remains in that sim's resources, and that includes prims rooted in one sim but sticking over the edge into another. Where the root prim or center of the single prim is determines where it is counted.

2: Any prims that stick over the line into the next sim are phantom as far as the other sim is concerned. BUT, when you are going from Sim A to sim B, for a short distance prims rooted in sim A can still support you. This is vital to cross-sim building, because when you step over the edge, the sim you are leaving doesn't think there is a prim there for you to step onto, unless there is a prim sticking over the border from its side. So you start to fall through as you step across. So you need to do a prim overlap on the border. One prim that is linked to the other side, sticking over the border from each side. I usually duplicate one full prim in both directions, linked to the far side and textured 100% alpha, while the prim it duplicates is one with a non-alpha texture.

3: You can't link a prim in sim A to a prim in sim B. So to have an overlapping prim that is entirely in sim A and linked to a linkset in sim B. you have to link it while it is in sim B, then edit linked parts to slide it over the edge into sim A.

Keep those facts in mind, and yes you can build over a sim border.

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Details on how to seamlessly create a prim bridge between two sims can be found here:

/8/86/247749/1.html

All it takes is 2 extra prims, with one half of the bridge or stairs on one side of the border, and the other half on the other side. Read the above thread for my detailed explanation.

That did the trick. Thank you !!

btw you are still going to fall when you zone from one sim to the other.. theonly way to fix this is to terraform a platform under your build (think of it as a landbridge) that way when they exchange sides they hit the terra and not the build.. just somthing you might want to know

Absolutely incorrect. Read what I posted above, and the thread I linked to. I have built several sim-crossing bridges with no land at all under them, and Linden Water many meters below the bridge at the crossing point, they work perfectly. I have also helped people to build continuous platforms and bridges at high elevations for sky builds that need to cross sim boundries.

I also have a castle drawbridge going across a sim border with the land a good drop underneath (wouldn't be much of a defence otherwise :/)... using the same approach as Ceera no problems with crossing.

I always wondered why the simulators cannot be programmed to do this automagically. That is, put some sort of prim along all sim boundaries that overhangs the next sim. With sculpties, they might even be able to make it look like land.

Communication delay is the problem.

In the instant while you are crossing the border from one sim to the next, the new sim needs to start processing a LOT of data about your avatar, their attachments, their position, and how you interact with what is near you in the sim. While it is receiving and processing that data, it assumes you are naked and there is nothing near you but terrain, and that is what causes the problems.

The "extend a prim into the other side" trick works by giving the first simulator more data to go on, so it can correctly predict your path as you cross. It "knows" there's another prim there to support you, even though it is sticking past the sim edge. But to be able to do that, it has to believe that there is a prim that is part of that linkset which extends out into "the unknown". I don't think you could properly automate adding a prim to a linkset that happens to touch a sim border.

I actually didn't create a linkset. I have one prim 2.98x 8.0x0.48 extending from Sim A to Sim B, with only 3.0 of the 8.0m overhanging into Sim B. Then a same sized prim overlapping the first going from SIM B to SIM A. Both of these are transparent. Then I use a 3.0x3.0x0.5 phantom prim to cover the two overlapping pieces, textured as the bridge.

Haven't fallen through since.