The following notes were taken from my audio recording and chat log of the Content Creation User Group (CCUG) meeting held on Thursday, December 1st 2022 at 13:00 SLT. These meetings are chaired by Vir Linden, and their dates and times can be obtained from the SL Public Calendar.
This is a summary of the key topics discussed in the meeting and is not intended to be a full transcript.
Note: unfortunately, my recording software failed at the 50 minute mark of the meeting, so the end of the meeting and the after-meeting discussion were not recorded, so some discussion points are missing from this summary.
Official Viewers Status
On Friday, December 2nd, the PBR Materials project viewer updated to version 126.96.36.1996966 on Friday December 2nd. This viewer will only function on the following Aditi (beta grid) regions: Materials1; Materials Adult and Rumpus Room 1 through 4.
The following reflect the rest of the current official viewers available through Linden Lab.
- Release viewer: version 188.8.131.526223 – MFA and TOS hotfix viewer – November 1 – No change.
- Release channel cohorts (please see my notes on manually installing RC viewer versions if you wish to install any release candidate(s) yourself).
- Performance Floater / Auto-FPS project viewer, version 184.108.40.2066737, November 28.
- Maintenance P (Preferences, Position and Paste) RC viewer version 220.127.116.116812 on Monday, November 28.
- VS 2022 RC viewer, version 18.104.22.1686310, issued November 4 – utilises Visual Studio 2022 in the Windows build tool chain.
- Project viewers:
General Viewer Notes
- The Lab is aiming to get the Maintenance P RC viewer promoted to release status before year-end.
glTF Materials and Reflection Probes
- 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.
- To provide support for reflection probes and cubemap reflections.
- The overall goal is to provide as much support for the glTF 2.0 specification as possible.
- The project viewer is available via the Alternate Viewers page, but will only work on the following regions on Aditi (the Beta grid): Materials1; Materials Adult and Rumpus Room 1 through 4.
- Please also see previous CCUG meeting summaries for further background on this project.
- Bugs and regressions continue to be reported via the project viewer on Aditi, and it is now unlikely the project will advance to a release state before early 2023 (end of 2022 always seemed ambitious).
- Despite hopes to the contrary, a lot of legacy content is impacted when rendered via the glTF PBR path, largely as a result of using linear alpha blending.
- As a result, LL are working on turning to smooth around some of the edge cases without having to introduce a code fork in the viewer between “legacy” alpha handling and PBR alpha handling.
- The aim remains to preserve as much of the appearance of legacy content under PBR rendering and reflection probes, without necessarily being slaved to preserving its looks over time. The major exception to this is would be situations where PBR rendering reveals seams between layers.
- However, if it proves necessary, an “opt out” button will be provided to switch out of linear alpha blending.
- mikkTSpace tangents affect all objects rendered in the PBR viewer. Unfortunately, due to the way mesh data has been stored prior to the PBR viewer, this means that creators wishing to get exactly the same results in their mesh models as they saw in their tool of choice (e.g. blender, etc.) when building their models, they will need to re-upload those models. This might result in a slight increase in the object’s Land Impact, if done.
- This does mean, however that all tangents on uploaded meshes will be correctly handled going forward.
- Capabilities will change with the PBR viewer: for example, there will be a basic glTF materials editor within the viewer; texture will rotate from a corner, rather than the centre (per the glTF specification extension for texture transforms); the upload will allow for the upload of individual materials from a glTF file.
Bakes on Mesh and Materials
- Providing materials support to Bakes on Mesh has been a long-standing request which has been thus far resisted by the Lab on the grounds of the impact it would have on the Bake Service – both in terms of code updates and the potential number of servers used.
- However, at the CCUG, Runitai and Vir floated the idea of materials on Bakes on Mesh being added – but only for the PBR rendering path. This would “drastically” cut down on the amount of back-end work required to make materials on BOM possible, and would mean that all avatar wearables would be Materials-capable.
- This is not something that has been currently road mapped for implementation at any time by LL, and it would require time and effort to determine a mechanism to manage it, but the support were there for it, it is something that might be considered.
- If this work was carried out, it might also pave the way for terrain painting – another popular request.
- As PBR Materials is released, it will become the focus for SL going forward; whilst efforts will be made to ensure “pre-PBR” contact continues to look right, whether or not work is put into trying to “pull” legacy materials content into PBR is questionable, simply because the layered complexity of the underpinning code =, the updating / altering of which can result in content breakage.
- As noted in the summary of the last meeting, there are reports that the PBR project viewer generating some 10% more CPU temperature and 17% more GPU temperature.
- LL are working on updates they hope will see any GPU increases return to the levels of the current release viewer.
- Issues with CPU temperature are not believed to be related to PBR, but more to general texture rendering, where a couple of errors have crept in and are being actively corrected.
- LODs and Land Impact:
- Lower value LODs on models. Some creators attempt to “game” Land Impact by having extremely low values as their low-end models, thinking they are “never seen”; unfortunately, these are seen by people running SL on very low-end machines and thus can account for new users feeling SL “looks rubbish due to the official viewer defaulting to a RenderVolumeLODFactor of 1.25.
- The RenderVoumeLODFactor setting will be more dynamic be default in the upcoming Performance Floater / Auto FPS viewer, although extremely lower LODs on models should still be avoided.
- More broadly, LL is still considering how to better adjust the Land Impact system and the mesh uploader so that creators are not penalised for creating accurate LODs on their models (one of the goals originally stated for project ARCTan).
- Linden Lab will be closed over the holiday period from end of business on Friday, December 23rd, 2022 through until start of business on Tuesday, January 3rd, 2023 (except for urgent support cases).
- Thursday, December 15th, 2022.