Variable regions come to OpenSim

Folks disappointed with the standard 16-acre region size can now have variable-sized regions in OpenSim, as long as they are comfortable running experimental code, and are using the latest viewers.

Those using the official release of OpenSim, will have to settle for megaregions for a while longer, however, as well as anyone using older viewers.

Today, there are variable regions up and running on OSgrid and Virtual Worlds Grid, but the implementation isn’t always easy, since this is still experimental code.

Virtual Worlds Grid founder Myron Curtis, for example, is still working at getting them to work right.

“The instructions at OpenSimulator.org seem incomplete,” he said.

He plans to have twelve varregions on his grid, each one 16 times as large as a standard region.

A variable region with mesh terrain by OpenSim developer Michael Emory Cerquoni — also known as Nebadon Izumi in-world.
A variable region with mesh terrain by OpenSim developer Michael Emory Cerquoni — also known as Nebadon Izumi in-world.

How they work

Varregions were originally developed as part of the Aurora-Sim fork of OpenSim, before being adapted to work with mainline OpenSim by Intel developer Robert Adams.

A varregion must be a square multiple of a standard region. So, for example, you could have a varregion that is the same size as two-by-two regular regions, or three-by-three, or four-by-four — all the way up t0 32 by 32. That means that a region can be as big as five miles — or eight kilometers — on each side. Or, to put it in another way, 1,024 regular regions — or 16,000 football fields.

It’s possible to load standard-sized OAR files into larger varregions — the instructions are here.

To create a varregion, you first have to install the experimental “master” version of OpenSim, then create a new standard region and reconfigure it as a varregion. OSgrid users can also download a version of OpenSim preconfigured to attach regions to OSgrid.

OSgrid region owner Scott Taylor has done just that, as he described in his post on the OpenSim Virtual community on Google Plus.

“After creating the region, I then shut down the console, modified the Regions.ini file to match the size I wanted, and started things back up again,” he said.

To visit the varregion, use a late-model viewer. Currently, the Singularity viewer is the one that’s recommended for varregions and other latest features of OpenSim as well as the latest Kokua viewer release. The latest version of Firestorm for OpenSim, 4.5.1, was released in October, and may not yet have full varregion support.

Comparing varregions and megaregions

Both varregions and megaregions allow OpenSim users to create larger regions. Both allow only sizes that are multiples of standard regions. Both allow easy vehicle use with no border crossings.

However, megaregions are a hack designed to work around viewer constraints inherited from Second Life, while varregions are built into the core of OpenSim, which results in a number of advantages.

“Megaregions worked by taking advantage of the fact that parts of the Linden Lab viewer implementation allowed regions larger than 256 by 256,” OpenSim core developer Justin Clark-Casey told Hypergrid Business. “However, many other bits required for proper support were missing, which is partly why OpenSimulator had to do very messy hacks.  It also suffered from various other bugs both because of this and deficiencies in the server side implementation.”

For example, he said, there were problems when users try to teleport to other parts of a megaregion other than its “root” region.

Varregions aren’t limited by viewer constraints — as long as the viewers are new enough that they support them — so any bugs that show up are fixable, he said.

Should you use varregions?

According to Clark-Casey, varregions will be part of the next official release of OpenSim, 0.8, but are not included in the current official release, which is 0.7.6.1.

He recommends that most users avoid them until 0.8 comes out.

“We are still in the process of working out regressions originating from a recent merge of unrelated code,” he said. “And varregions themselves are likely to still have issues.”

Until then, he recommends that only developers and testers use the experimental varregions code.

After OpenSimulator 0.8 is released, Clark-Casey says that users should opt for varregions instead of megaregions whenever possible.

“However, if one needs to provide access to older viewers then you would have to stick with megaregions,” he added.

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