Day: October 20, 2023

2023 week #42: SL CCUG meeting summary: PBR

Posted on by Inara Pey
Meditation Mountain, August 2023 – blog post †

The following notes were taken from my audio recording and chat log transcript of the Content Creators User Group (CCUG) meeting held on Thursday, October 19th, 2023. Unfortunately, my recording software glitched (I tend to be afk when the meeting is in progress), so only the first 18 minutes of the meeting were actually recorded to disk, as represented here.

  • The CCUG meeting is for discussion of work related to content creation in Second Life, including current and upcoming LL projects, and encompasses requests or comments from the community, together with viewer development work.
  • As a rule, these meetings are:
    • Held in-world and chaired by Vir Linden.
    • Conducted in a mix of voice and text.
    • Held at 13:00 SLT on their respective days.
    • Are subject to the schedule set within the SL Public Calendar, which includes the location for the meetings.
    • Open to all with an interest in content creation.
  • The notes herein are drawn from a mix of my own chat log and audio recording of the meeting, and are not intended to be a full transcript.

Viewer Updates

Friday, October 20th saw the release of the Github Actions (GHA) viewer, version 6.6.16.6566955269. This is the first official viewer to be built via Github Actions rather than TeamCity.

  • Outside of a major version update to CEF (Chromium Embedded Framework) which includes several performance updates and security fixes, this viewer contains no user-observable differences to the current release viewer…
  • .. Other than having even more crunchy digits in the version number for us all to chew on.
  • Release viewer, version 6.6.15.581961, promoted October 2 (formerly the Inventory Extensions Viewer).
  • Release channel cohorts (please see my notes on manually installing RC viewer versions if you wish to install any release candidate(s) yourself).
  • Project viewers:

glTF Materials and Reflection Probes

Project Summary

  • To provide support for PBR materials using the core glTF 2.0 specification Section 3.9 and using mikkTSpace tangents, including the ability to have PBR Materials assets which can be applied to surfaces and also traded / sold.
  • The overall goal for glTF as a whole is to provide as much support for the glTF 2.0 specification as possible.
  • Up to four texture maps are supported for PBR Materials: the base colour (which includes the alpha); normal; metallic / roughness; and emissive, each with independent scaling.
  • In the near-term, glTF materials assets are materials scenes that don’t have any nodes / geometry, they only have the materials array, and there is only one material in that array.
  • As a part of this work, PBR Materials will see the introduction of reflection probes which can be used to generate reflections (via cubemaps) on in-world surfaces. These will be a mix of automatically-place and manually place probes (with the ability to move either).
  • The viewer is available via the Alternate Viewers page.

Further Resources

General Status

  • The back-end communications / bandwidth fix has been deployed to all PBR test regions, per this blog post from the Lab.
  • The push is now on to get glTF PBR to a point where the simulator side code can be more broadly deployed to an RC channel. This may result in some regressions being noted, but this will be subject to point releases to correct, should they occur.
  • On the viewer side, there will be a focus on getting the Mac version up to match the performance seen with the windows PBR RC viewer.
  • Because of the above, and as the viewer moves forward, the recommendation for those testing PBR is to read the available documentation – particularly the viewer release notes.
  • The general word to those testing PBR is that if they do come across anything that could be a major issue, to be sure to Jira it ASAP and in as much details as possible, and if active in the content Creation Discord Channel (which, for those who ask, I have been specifically asked by LL not to provide links to in these pages), to speak up.
  • This focus on trying to get PBR Materials out means that the work on real-time mirrors and on glTF terrain has been put on a temporary hold to maximise the resources available for Materials work.

Mirrors

  • Mirrors are a part of the glTF / PBR materials project, but something of a separate tranche of work.
  • The idea is provide the means to have via high resolution reflections (i.e. mirrors) within a scene.
  • Initially only one active mirror surface per scene will be active for any viewer.
  • The process will use the PBR reflection probes mechanism, combined with a automated “Hero Probe” mechanism which with generate high resolution (512×512) “reflections” for the mirror.
  • The system will operate on the basis of avatar / camera proximity to a mirror surface triggering the closest reflection probe to become a “Hero Probe” for that avatar / camera. This means that if there are multiple mirrors placed within an environment, only the one closest to a given avatar / camera will be active and display the “reflections” generated by the reflection probe.
  • Depending on testing and performance, the number of mirrors might be expanded to two – one for mirror surfaces and one for Linden Water to generate high resolution water reflections where appropriate.

Status

  • As noted above, work temporarily on hold to focus resources on PBR Materials.

In Brief

  • There was a general discussion on how best to change an preserve overrides on materials when allowing for the likes of colour changes when making changes via LSL (and how best to batch similar changes). This was seen as something that could be better handled outside of LSL directly (thus avoiding multiple calls to set / preserve specific changes), but is something to be looked at after the initial release.
  • At this point the recording flatlined 😦 .

Next Meeting

† 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 gathering of people every week. They are taken from my list of region visits, with a link to the post for those interested.