2023 week #18: SL CCUG meeting summary – PBR

Elvion, March 2023 – blog post †

The following notes were taken from my audio recording and chat log transcript of the Content Creation User Group (CCUG) meeting held on Thursday, May 4th, 2023 at 13:00 SLT. 

These meetings are for discussion of work related to content creation in Second Life, including current work, upcoming work, and requests or comments from the community, together with viewer development work. They are usually chaired by Vir Linden, and dates and times can be obtained from the SL Public Calendar.


  • These meetings are conducted in mixed voice and text chat. Participants can use either to make comments / ask or respond to comments, but note that you will need Voice to be enabled to hear responses and comments from the Linden reps and other using it. If you have issues with hearing or following the voice discussions, please inform the Lindens at the meeting.
  • The following is a summary of the key topics discussed in the meeting, and is not intended to be a full transcript of all points raised.

Official Viewer Status

No updates through until the meeting, leaving the official viewer pipelines as:

  • Release viewer: Performance Floater / Auto FPS RC viewer, version, promoted April 25.
  • 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:
    • Puppetry project viewer, version, December 8, 2022.

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.
  • There is a general introduction / overview / guide to authoring PBR Materials available via the Second Life Wiki.
  • Substance Painter is also used as a guiding principal for how PBR materials should look in Second Life.
  • 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.
  • Given the additional texture load, work has been put into improving texture handling within the PBR viewer.
  • 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.
    • It is currently to early to state how this might change when glTF support is expanded to include entire objects.
  • The overall goal is to provide as much support for the glTF 2.0 specification as possible.
  • To provide support for reflection probes and cubemap reflections.
  • The viewer is available via the Alternate Viewers page.
  • Please also see previous CCUG meeting summaries for further background on this project.


  • The viewer is now at Release Candidate status, per the viewer update list above. HOWEVER, the server-side support for glTF / PBR is still awaiting deployment to the Preflight RC channel on the main grid, so for the time being, the viewer still only works on Aditi (the Beta grid), on the following regions: Materials1, Materials Adult, Rumpus Room and Rumpus Room 2 through 4.
  • The viewer will remain in RC for some time to allow for broader feedback to be gained, particularly once the server support has been deployed to simhosts on Preflight (and, most likely Snack as a follow-on), and so is more amenable for testing by a wider group of users / creators.
  • As always, those who do find significant issues in using the viewer in RC are asked to report them via a BUG report ASAP.
  • Runitai Linden (aka Dave P), has been working on avatar performance with PBR, hoping to up the performance a little further, as well as continuing to refine reflection probes.
  • Brad Linden continues to work on bug fixing, improving network traffic overheads, etc.
  • A new addition to the PBR viewer is a reflection probe visualisation debug tool, allowing the volume of space specific probes are influencing to be seen, allowing people to better understand where reflections on surfaces are coming from, etc.
  • Application priorities: if a surface had either only PBR Materials applied, or PBR overlaying the “traditional” SL materials, it will be rendered according to the glTF specification. If an object has faces with different materials types (e.g. PBR Materials on some faces – such as the sides of a prim cube, and “traditional” SL materials on the others), the viewer will render the PDR faces via the the PBR renderer, and those face with the older materials in a manner consistent with how the should appear if rendered on a non-PBR viewer.

PBR Resources for Testing

  • There have been some requests for content to test PBR Materials against. Content has been provided (by LL and some of the creators testing PBR Materials already) on Aditi, and some of this could potentially be ported.
  • One suggestion was to make a sandbox available for PBR testing, allowing creators to build / import their own content and test it under different EEP settings (e.g. their own / those in the Library), using the Apply Only to Myself option.
  • Custom EEP settings are one particular area of testing that EEP creators might want to look at (both in terms of the PBR viewer and also with any PBR Materials test content). This is because there have been some changes made to the environment rendering in the PBR viewer which might impact some custom EEP settings, which may require them to be adjusted / updated and / or BUG reports raised against significant issues.
  • For those wishing to gain familiarity with PBR Materials in general, their is the SL Wiki entry for it, and it has been suggested some general test content could be provided through that page.

Future glTF Work

  • Geenz Linden is actively working on real-time mirror as a future follow-on project from the PBR Materials work, as well as working on Screen Space Reflections

Next Meeting

  • Thursday, May 18th, 2023.

† 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.


Have any thoughts?

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.