Day: November 17, 2023

2023 week #46: SL CCUG meeting summary: PBR status & current release plan

Posted on by Inara Pey
Le’eaf Forest Retreat, September 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, November 16th, 2023.

  • 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, in accordance with the dates and times given in the the SL Public Calendar, which also includes the location for the meetings.
    • Conducted in a mix of voice and text..
    • Open to all with an interest in content creation.
  • The notes herein are a summary of topics discussed and are not intended to be a full transcript.

Official Viewers Status

No updates for the latter part of the week, with the current crop of official viewers being:

  • Github Actions (GHA) RC viewer, version 6.6.16.6566955269, issued October 20 (with major CEF update and number version numbering) and promoted on October 25.
  • Release channel cohorts:
    • Maintenance X RC, version 6855926535, issued November 14 – usability improvements.
    • Maintenance Y, version 6.6.17.6855930358, issued November 14 – My Outfits folder improvements; ability to remove entries from landmark history.
    • glTF / PBR Materials viewer, version 7.0.1.6750600769, November 11.
    • Maintenance-W RC viewer, version 6.6.17.6709258523, November 9.
    • Maintenance V(ersatility) RC viewer, version 6.6.16.582201, October 16.
    • Emoji RC viewer, version 6.6.15.581551, August 31.
  • Project viewers:

General Notes

  • The PBR viewer now appears to be the no 1 on the runway for promotion to release status – see the notes below for more.
  • The next viewer LL is hoping to promote after PBR is the Emoji RC viewer.
  • As there are now four Maintenance RC viewer in the pipeline (V, W, X, and Y), it is likely some of them will be merged together to reduce the load on the release schedule.

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

Grid-Wide Deployment and Viewer Release

  • Following a meeting this week, the current plan from the Lab is to deploy PBR Materials grid-wide on the simhosts during the first week after US Thanksgiving (so week commencing Monday, November 27th, 2023).
  • Currently, all RC simhost have been updated to the PBR simulator code which leaves only the SLS Main channel to go.
  • The plan is also to promote the PBR RC viewer to de facto release status that same week.
  • Note that these plans are subject to late-breaking issues or other requirements not getting in the way of things.

Recent Work

  • Fixes are progress for what are seen as to remaining notable issues:
    • One to correct the issue with normal maps uploaded via the glTF uploader always coming out square post-upload  and with lossy compression.
    • One to correct the issue of not being able to revert an Alpha mode from blend or mask to opaque without having to save the material back to inventory after making the change in order for it to apply properly.
  • There are some additional bugs within the system, some of which do have fixes in the works, but these aren’t seen as having significant impact, and will be subject to release with the first maintenance update to PBR Materials.
  • That said, there some issues which have been identified, but will not be addressed until the first PBR maintenance viewer is issued. These include:
    • A “slim minority” of users with very, very large inventories and Friends lists may find some objects in a scene do not render when logging-in. Currently, the steps for correcting this are to a) re-log, and if that fails to resolve the problem, b) clear cache.
    • Some users on Macbooks and / or Apple Silicon systems may experience poor performance on the PBR viewer.
  • For those interested – this is the list of currently open issues for PBR.

General PBR Discussion

  • BUG-234235 “[PBR] alpha blend on water is acting a bit like invisiprim” – this is being worked on, and is seen as somewhat related to another change under consideration: environmental haze.
    • Currently, local lights are not affected by environmental haze. Runitai Linden is working on a change that will make local lights responsive to haze (e.g. if you are in a foggy environment, lights at an increasing distance from your camera position will appear fainter and fainter due to the influence of the fog).
    • This work will likely be surfaced in the first PBR viewer maintenance release.
    • The reason this is related to BUG-234235 is that it will also require an adjustment to water haze as well, and this should resolve the issue reported in the bug (haze will essentially get its own render pass, with a single shader being used for both atmospheric and water haze, rather than them requiring separate render passes).
  • Future work on glTF will allow for more greater control of lighting sources, such as lamps, etc., and provide for luminosity to be defined in terms such as lumens. However, this work will depend on glTF scene import, which will be worked on in the next tranche of work, together with HDRI import / export (which is not as yet on the glTF implementation roadmap).
  • A Materials folder is to be added to the system library and available through the Library section of inventory.

In Brief

  • A Feature Request has been filed to allow system-generated sounds to be overridden by Experiences to provide more immersive sounds (e.g. on entering a door and being teleported, the sound heard might be the creaking of the door opening, rather than the ding-sing-whoosh of the default teleport sound – which can only currently be disabled on a per viewer basis by the user). See (and Watch) BUG-234682 “Override UI sounds within the scope of experience keys” for more.

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.