Category: SL User Group Meetings

The following notes were taken from the Tuesday, November 11th, 2025 Simulator User Group (SUG) meeting. These notes form a summary of the items discussed, and are not intended to be a full transcript. They were taken from the video recording by Pantera, embedded at the end of this summary – my thanks to Pantera for providing it.

Meeting Overview

• The Simulator User Group (also referred to by its older name of Server User Group) exists to provide an opportunity for discussion about simulator technology, bugs, and feature ideas is held every other Tuesday at 12:00 noon, SLT (holidays, etc., allowing), per the Second Life Public Calendar.
• The “SUG Leviathan Hour” meetings are held on the Tuesdays which do not have a formal SUG meeting, and are chaired by Leviathan Linden. They are more brainstorming / general discussion sessions.
• Meetings are held in text in-world, at this location.

Simulator Deployments

• On Tuesday, November 11th, the SLS Main channel was restarted without any deployment.
• On Wednesday, November 12th:
  • All RC channels other than BlueSteel and Preflight should be updated with a new simulator update (Imbu). This “has a couple of performance memory fixes in the simulator. It fixes an issue with region names that contain a ‘.”
  • The BlueSteel and Preflight RC channels will be restarted without any update.

SLua Work

• Rider Linden has been refactoring some of the official native VS Code plugin for LSL and SLua, and is planning on opening it up and making the repository public on Friday, November 14th.
• There was a SLua update on the beta grid during week #45:
  • Release notes.
  • SLua source Code repository.
• Since then, Harold has been cleaning up the bugs found with that release, with the aim of getting a limited deploy to a few simulators on Agni (the Main grid) later in November. This will be to simulators hosting Lab-managed regions; “volunteer” regions from region holders will be accepted further down the deployment road.
• Viewer-side support for SLua is also defined as “iffy” – an update to the viewer has been anticipated, but work on it is pending Harold competing the work fixing the bugs in the simulator deployment.
• A question was asked as to why vectors and quaternions are immutable in SLua. In reply, Harold stated:

Vectors are immutable because that’s just how it is in Luau, they’re not garbage-collected, they’re a value type. Storing a vector is exactly as cheap as storing a number. Quaternions _are_ garbage collected but they’re immutable for symmetry with how vectors work, and honestly people don’t tend to create a bajillion of them per frame so IDK if making them mutable is worth it. GC overhead isn’t something you have to worry about so much since we abstract away most of the GC details. 

They’re not reference types so mutability probably wouldn’t work the way anyone would expect without special language support that would be hard. In reality, they were never mutable in LSL either, it just sort of pretended they were by hiding the fact that it was actually making a whole new vector.

• • Harold also noted that he settled on the canonical name “quaternion” in SLua because it’s easier to google what to do with them compared to “rotation”(which could mean anything), but he is open to ideas on this. The term appeared to find acceptance among those at the meeting, with the conversion flowing through the middle third of the meeting.
• It was asked if it would be possible to add more functions to SL standard SLua libraries – e.g. someone writes really commonly used functions that might then – be included in common/native libraries?
  • The reply was yes, it is possible, but currently LL are being conservative because while it is relatively easy to add things, it is harder to removed them later if they turn out to be a bad abstraction or similar.
  • This led to a broader discussion on SLua scripting, etc.

In Brief

• Leviathan Linden has been carrying out Voice related work, but is now “almost done” with that. He is currently focusing back on simulator crash and performance issues.
• Leviathan also provided some feedback on a question from his “office hours” meeting on November 4th:

[I was asked] last week about some bugs in llBase64ToString() method. Apparently it was designed to replace C0 control codes (chars with numerical values < 32) with “?”, and fails to replace a C0 character if it is at the end of the string. I looked at the code and as far as I can tell that really is a bug… we skip the last character of the string for an “off by one” error. It has been around since before 2007. The question is: can we fix it?

• • It was suggested that either LL should make a new llBase64ToStringFixed() LSL function so as to preserve compatibility with old scripts implementing their own workaround; or a fix similar to that for XorBase64* is implemented.
• Monty Linden is “looking into weird bugs and doing a project related to mobile.”
• Pepper Linden has been carrying out more Conductor work to help with region packing. Pepper has also been engaged in the work on outfits support for the next SL Mobile update.
• A question was asked on the status of long-discussed possible updates / improvements to in-world Land Impact calculations (such as removing Scale as a factor, as had been most “recently” discussed in SUG meetings). In short: no real progress at this time, due to the issue being somewhat complicated.
  • This led to a conversation on Land Impact, LODs (and LOd decimation) allowing larger megaprims, etc.
• Also flowing through themeeting was a conversation relating to region sizes, region crossings, water planes, etc.

Date of Next Meetings

• Leviathan Linden: Tuesday, November 18th, 2025.
• Formal SUG meeting: Tuesday, November 25th, 2025.

† The header images included in these summaries are not intended to represent anything discussed at the meetings; they are simply here to avoid a repeated image of a rooftop of people every week. They are taken from my list of region visits, with a link to the post for those interested.

The following notes were taken from the Tuesday, October 28th, 2025 Simulator User Group (SUG) meeting. These notes form a summary of the items discussed, and are not intended to be a full transcript. They were taken from the video recording by Pantera, embedded at the end of this summary – my thanks to Pantera for providing it.

Meeting Overview

• The Simulator User Group (also referred to by its older name of Server User Group) exists to provide an opportunity for discussion about simulator technology, bugs, and feature ideas is held every other Tuesday at 12:00 noon, SLT (holidays, etc., allowing), per the Second Life Public Calendar.
• The “SUG Leviathan Hour” meetings are held on the Tuesdays which do not have a formal SUG meeting, and are chaired by Leviathan Linden. They are more brainstorming / general discussion sessions.
• Meetings are held in text in-world, at this location.

Simulator Deployments

• On Tuesday, October 28th, the SLS Main channel was restarted without any deployment.
• On Wednesday, October 29th:
  • The BlueSteel RC channel should be updated with a new simulator update (Imbu). This “has a couple of performance memory fixes in the simulator. It fixes an issue with region names that contain a ‘.”
  • The remaining RC channels will (I believe) be restarted without any update.

SLua Work

• Harold Linden continues to work on the SLua implementation, focusing on some minor API changes, which he initially defined as: “just tons of lingering issues to file off sharp edges on APIs to make them do what people would reasonably expect.” Later in the meeting, he further expanded on the first of these changes thus:

I was looking to clear up one of the big warts of LSL: “keys” are not strictly UUIDs, they’re strings in disguise. That means the UUIDs that vary only in casing are considered unequal, which is very weird if you’re used to more modern UUID APIs. The only cases where people generally want that behaviour is in llMessageLinked() / ‘link_message()’ so you can pass an extra string as ‘id’, but it causes weird unexpected issues elsewhere. In SLua, I’d like to make ‘UUID()’ return nil if the passed-in string is not a valid UUID, like the existing Lua functions do, and make [the] ‘link_message()’ ID field just a string, because people mostly mash arbitrary strings in there. … All APIs that accept key or string in SLua are implicitly a union of ‘string | UUID’, and that doesn’t change. 

• • This approach was welcomed by the majority of scripters at the meeting.
  • As a part of this discussion, it was suggested that SL could benefit from an improved llMessageScript, such as llMessageScript(scriptname,data), and Harold Linden indicated that something like this is being planned.
• The other API change Harold is working on is the removal of ‘integer()’, which he views as having been only a temporary requirement, but is now no longer needed as he has “fixed up all the bridges to existing LSL functions to tolerate a Lua number”. As such, he regards it as a nuisance to developers as it is likely to slow scripts and make them hard to optimise, as the Luau optimiser doesn’t know about it.
• Harold also noted that he is not opposed to “adding stuff” to LSL on SLua (e.g. such as a table type), however, given the amount of foundational work that’s considered a higher priority, this is unlikely to happen soon (if at all).
  • Rider Linden also noted that such work would not be a small task, and as such, nothing is currently on the drawing board as yet.
• Yardang, one of the SLua regions on Aditi has been down for possibly as long as a week. Rider Linden has requested that anyone testing SLua who notes any if the the associated regions appears to be down to contact him in-world.
• Rider was engaged in a couple of technical debt projects over the course of the past week but is now now working on the official native VSCode plugin for LSL and SLua once more. The hope is to have this deployed in the upcoming week, although it will need further tweaking when the next version of the SLua project viewer is issued.
• The first half of the meeting included a general discussion /catch-up on the above and related work, including:
  • The plugin should support linting (check a script for errors without running it) and also downloads the current language definition from the viewer and formats it so Luau-LSP and Selene can use it.
  • Wolfgang Senizen has also produced a VSCode plugin + documentation for use with SLua, although notes this will likely be discontinued when the official plugin is made available, and he will shift to contributing code to that project.
  • A note that LSL/SLua functions cannot be directly called from outside of the simulator (e.g. via a web page), but “in theory” it might be possible to create an RPC (bot) service of some kind to achieve the same.
  • Harold Linden reiterated that LL is working on a new LSL / SLua web portal, which will include documentation and code examples, etc.
• The latter part of the meeting focused on suggestions for future SLua support, and discussions on the use of JSON / LLSD – please refer to the video for details.

In Brief

• Harold and Leviathan Linden have been working on fixes for script scheduling (“do with have to do anything for this script / are we allowed to run it?”), and which should reduce script times on a simulator “a reasonable amount”.
• Additionally, Leviathan Linden is working on fixing more memory leaks within the simulator code, noting that those fixed in the upcoming Imbu release are “small potatoes” compared to what the Lab thinks is out there.
• Leviathan is also hoping to get back to the game_control work in the the near(ish) future, noting, “I have a link to the Linux viewer branch (which is almost deliverable) and I will be building on top of that”.
• Given the lateness of the year and the limited time for further simulator updates, it is unlikely there will be further work on region crossings during 2025.

Date of Next Meetings

• Leviathan Linden: Tuesday, November 4th, 2025.
• Formal SUG meeting: Tuesday, November 11th, 2025.

† The header images included in these summaries are not intended to represent anything discussed at the meetings; they are simply here to avoid a repeated image of a rooftop of people every week. They are taken from my list of region visits, with a link to the post for those interested.