Category: SL User Group Meetings

2023 week #20: SL CCUG meeting summary: mirrors and PBR terrain

Posted on by Inara Pey
Small Town Green, 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 18th, 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.

Notes:

  • These meetings are conducted in mixed voice and text chat. Participants can use either when making comments  or 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.

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.
  • 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.

Status

  • The RC glTF / PBR viewer was updated to version 7.0.0.580085 on Tuesday. May 16th.
  • Work is continuing to try to fix the issues with pre-PBR skies looking “broken” in the PBR viewer. This is seen as the last major fix required to the viewer, the rest of the required work being seen as or “maintenance” fixes rather than major breakages
    • The probable solution for the sky issue is to use the reflection probe ambience as a hint as to how the sky should rendered. If the ambience setting is zero, various environment sliders such as Brightest (currently referred to a Gamma in the viewer) should respond in much the same way as they do in pre-PBR viewers. Otherwise the sky will be rendered as PDR / HDR.
    • This is acknowledged as being something of a kludge, but is seen as a easiest way to maintain rendering for non glTF / PBR scenes.
  • Water reflections: the glTF / PBR viewer includes updates to the rendering of Linden Water reflections.
    • These are seen as being “not as good” as water reflections seen in non-PBR viewers, but they run with a lot less in the way of overhead on the viewer.
    • The reduction in reflection quality is the result of no longer doing a full rendering pass on Linden Water, and the decision to do this was made to offset the cost of reflection probes and planar mirrors (see below).

Screen Space Reflections and Mirrors

  • Screen Space Reflections (SSR) – (non-SL overview):
    • Now supports both glossy and “stupid” roughness values, with “good” performance, and supports adaptive sampling rates.
    • SRR will apply to “everything” in a scene.
    • The same approach taken with SSR will also be used for planar mirrors.
  • Planar mirrors:
    • Geenz Linden is working on both occlusion culling (at what distance from an avatar / camera should mirrors render) and general mirror constraints (how many mirrors should be active for an avatar at any given time). There are currently no plans to limit mirrors on the basis of size.
    • The latter will most likely initially be set to one, and if there are multiple mirrors within range of an avatar, only the nearest will have reflections actively rendered, the rest will simply render as glossy surfaces.
    • The distance culling is unlikely to exceed 12 m, and there are cases (e.g. some Linden Homes regions) where it would be best suited as being a lot less, to avoid situations where someone has a mirror in their home – but it is impacting their neighbours’ rendering.
    • The rate of update for mirrors might be throttled; a decision has not been taken on this as yet.
    • The limitations are unlikely to have debug overrides (although this might change in part for some as testing progresses) in order to prevent people from inadvertently crippling their frame rates. In this latter regard, Geenz notes:  “The performance sucks, the use cases are limited, and you should plan accordingly.”
    • Rendering takes the form of: reculling the scene from the perspective of the mirror, re-rendering that scene into the G-Buffer, re-shading that scene in the deferred pass, and finally re-rendering semi-transparent objects – all of which is intensive.
  • The intent: LL want to get to a point where SSR and reflection probes should be sufficient for more reflection use-cases. Mirrors should only ever used in exceptional cases where SSR and reflection probes cannot achieve the desired effect (i.e. the shiny metal coffee pot on the table and the “glass” on the picture frame on the wall should both utilise SSR / reflection probes for the reflections on their surfaces and not be set as a mirror).

PBR Terrain

  • As per my TPVD summary for Friday, May 12th, there is a project underway to provide PBR support for terrain.
  • This is seen as a means of leveraging PBR Materials to offer some quality improvements to terrain ahead of any longer-term terrain project which might yet be considered / actioned.
  • The idea is to enable the use of Materials asset IDs in place of the usual texture IDs and applying them to the ground.
  • An initial alpha build of a viewer supporting this work is available through the content creation Discord server. However, note that it is only alpha and unsupported outside of the project at this time.
    • Please also note that at the request of Linden Lab, I am unable to publish details on how creators can obtain access to the content creation Discord server. Those who are interested should wither a) attend a Content Creation User Group meeting and request access there; or b) contact Vir Linden to request details on how to request access.
  • As this is purely a viewer-side change, it does not require a server-side update, but for testing, the viewer should preferably be used on Aditi (the beta grid), where there are materials available within the PBR regions expressly for testing the capability. There is also a debug setting in the viewer which allows it to be used “anywhere”, but this is described as currently “hacky”.
  • This work also sees an increase in the overall texel density for terrain, raising it to 1024×1024, and the texture repeat has been doubled. The latter may only be a temporary move, with discussions at LL revolving around various ideas such as hex tiling.
An example of PBR materials applied to Second Life Terrain. Via Niri Nebula, original by Animats
  • Important notes with this work:
    • It is not terrain painting. It is the application of PBR materials – terrain painting is described as “something that’s on the radar” at LL.
    • The work does not include support for displacement maps.
    • The work is currently only viewer-side, with no corresponding server-side support, the idea here being to prototype what might be achieved and testing approaches / results.
    • It is viewed as a “mini project”, which can potentially be built upon to include elements such as simulator support (including EM tools, etc.).
    • Given the above point, there are also discussions on how best to handle the default grass texture for land (which is just a basic diffuse map) if the PBR terrain work is to go mainstream. Currently, updating this is not part of the mini-project.

glTF and the Future

  • glTF “phase one”: PBR materials (current project).
  • glTF “phase two”: mesh asset uploads support and scenes (up to, but not including animations).
  • glTF “phase three”: animations, morph targets, etc.

Next Meeting

  • Thursday, June 1st, 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.

2023 SL SUG meetings week #20 summary

Posted on by Inara Pey
Borkum, March 2023 – blog post

The following notes were taken from the Tuesday, May 16th Simulator User Group (SUG) meeting. They form a summary of the items discussed and is not intended to be a full transcript. A video of the entire meeting is embedded at the end of the article for those wishing to review the meeting in full – my thanks to Pantera for recording it.

Server Deployments

  • On Tuesday, May 16th, the SLS Main channel servers were restarted without any deployment, leaving them on simulator release 579747.
  • On Wednesday, May 17th, a new simulator release will be made to the BlueSteel RC channel. This contains configuration changes on to help support the new “Social Casino“.

Viewer Updates

On Tuesday, May 16th:

  • The Maintenance S RC viewer, version 6.6.12.579987, dated May 11, was promoted to de facto release status.
  • PBR Materials project viewer updated to version 7.0.0.580085.

The rest of the pipelines remain as:

  • Release channel cohorts:
  • Project viewers:

Region Crossings

This took up a major part of the meeting.

  • BUG-227303 – “collisions makes a script stop running and revert its mono status” is still causing headaches, despite a recent attempt to stomp it. Rider Linden is going to attempt a test configuration set-up with the theory that the issue might be related to transfers between physical simhost server, rather than between simulators.
    • This came with a suggestion that those experiencing the issue should provide a detailed summary of where / when and – particularly – how they encountered the problem and, if possible supply him with the vehicles in use at the time the problem was encountered.
    • A further suggestion was made that those who experience the problem and have hight ping times to the servers (and a means to accurately repro the issue) invite Rider to ride with them and witness the problem first-hand and in real time, in case it is related to network latency.
  • BUG-233691 “Animesh re-renders at lowest LOD for extended interval after long-range llSetRegionPos” – whilst not strictly a region crossing issue, it can be experienced on a region crossing. It is believed a fix is currently in the PBR RC viewer.
  • For full details on the discussion, please refer to the video, below.

In Brief

  • BUG-232037 “Avatar Online Offline Status Not Correctly Updating” – work is in progress on a further fix, and will be included in an upcoming simulator maintenance release.
  • The last part of the meeting is a general discussion on LSD, pivot points, the glTF specification. Refer to the last 20 minutes of the video for details.

† 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.

2023 week #19: SL TPVD meeting summary (PBR terrain)

Posted on by Inara Pey
Dragonfly, March 2023 – blog post
The following notes were taken from my audio recording and chat log transcript of the TPV Developer (TPVD) meeting held on Friday, May 12th 2023 at 13:00 SLT. Meeting Overview
  • The TPV Developer meeting provides an opportunity for discussion about the development of, and features for, the Second Life viewer, and for Linden Lab viewer developers and third-party viewer (TPV) / open-source code contributors to discuss general viewer development.
  • As a rule, these meetings are:
    • Generally held once a month  the third or fourth Friday, at 13:00 SLT at the Hippotropolis Theatre. See the SL Public Calendar for specific meeting dates.
    • Open to all with an interest in viewer development.
    • Conducted in a mix of text and voice.
  • 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.

Official Viewers Status

General Viewer Notes

  • Inventory thumbnails viewer: work is progressing and a public-facing viewer should be available in the “not too distant future”.
    • The viewer-side work to support emojis is now more-or-less complete, and release of any project viewer is pending some additional back-end work.
  • There will be changes coming to the Second Life System Requirements, minimum specifications:
    • Mac OSX will be set at version 11.
    • Window 32-bit is liable to be dropped.
  • LL is close to completing the move of viewer builds to Github Actions. This has involved getting many of the 3rd party libraries for the viewer updated and refreshing all build dependencies.
  • This work also means that the Chromium Embedded Framework (CEF) for media handling is being updated.

Terrain “Mini Project”

  • There is a project underway to provide PDR support for terrain.
  • The overall scope is not clear, but it apparently exploits an asset-checking weakness in the simulator code related to terrain, allowing the use of Materials asset IDs in place of the usual texture  IDs, allowing them to be applied to the ground.
  • This is seen as a means of leveraging PBR Materials to offer some quality improvements to terrain ahead of any longer-term terrain project which might yet be considered / actioned.
  • It is hoped that this work will be available in a project viewer Soon™.

In Brief

  • PBR Materials mini-update:
    • Overall visual quality is pretty much where it will be when the viewer reaches formal release status.
    • There are still issues with rendering the sky – such as alpha glitching on the Sun. This is being worked on, but it is unlikely to see an imminent solution / viewer update.
    • Other known issues are also being worked on and progress is being made in clearing them.
  • A general discussion of the on-line  / off-line friends issues (frequently raised t the Server User Group meetings) – see BUG-232037 “Avatar Online Offline Status Not Correctly Updating”. As per notes from that meeting, the UDP fix does not appear to have had the desired impact in helping to reduce the issue, and LL are looking at the matter again.
  • A lot of general chat on WIP regarding PBR Materials and reflection probes, most of it relating to issues likely to be addressed – please refer to the video.
  • A general discussion on possible standards for avatar “metaverse interoperability” which runs through the latter half of the meeting. As a theoretical discussion rather than something LL is working on, please refer to the video.
  • There is also some further discussion on the Puppetry project, however, this will form an addendum to my recent Puppetry Project meeting summary, as it is more relevant there.

 Next Meeting

  • Friday, June 9th, 2023.

2023 SL Puppetry project week #19 summary

Posted on by Inara Pey

Puppetry demonstration via Linden Lab – see below.  Demos video with the LL comment “We have some basic things working with a webcam and Second Life but there’s more to do before it’s as animated as we want.”

Note: this has been updated to include comments made at the TPV Developer meeting on Friday, May 12th.

The following notes have been taken from chat logs and audio recording of the Thursday, May 11th, 2023 Puppetry Project meetings held at the Castelet Puppetry Theatre on Aditi. These meetings are generally held on alternate weeks to the Content Creation User Group (CCUG), on same day / time (Thursdays at 13:00 SLT).

Notes in these summaries are not intended to be a full transcript of every meeting, but to highlight project progress / major topics of discussion.

Project Summary

General Project Description as Originally Conceived

LL’s renewed interest in puppetry was primarily instigated by Philip joining LL as official advisor, and so it really was about streaming mocap. That is what Philip was interested in and why we started looking at it again. However since Puppetry’s announcement what I’ve been hearing from many SL Residents is: what they really want from “puppetry” is more physicality of the avatar in-world: picking up objects, holding hands, higher fidelity collisions. 
As a result, that is what I’ve been contemplating: how to improve the control and physicality of the avatar. Can that be the new improved direction of the Puppetry project? How to do it?

Leviathan Linden

  • Previously referred to as “avatar expressiveness”, Puppetry is intended to provide a means by which avatars can mimic physical world actions by their owners (e.g. head, hand, arm movements) through tools such as a webcam and using technologies like inverse kinematics (IK) and the  LLSD Event API Plug-in (LEAP) system.
    • Note that facial expressions and finger movements are not currently enabled.
    • Most movement is in the 2D plain (e.g., hand movements from side-to-side but not forward / back), due to limitations with things like depth of field tracking through a webcam, which has yet to be addressed.
  • The back-end support for the capability is only available on Aditi (the Beta grid) and within the following regions: Bunraku, Marionette, and Castelet.
  • Puppetry requires the use of a dedicated viewer, the Project Puppetry viewer, available through the official Second Life Alternate Viewers page.
  • No other special needs beyond the project viewer are required to “see” Puppetry animations. However, to use the capability to animate your own avatar and broadcast the results, requires additional work – refer to the links below.
  • There is a Puppetry Discord channel – those wishing to join it should contact members of LL’s puppetry team, e.g. Aura Linden, Simon Linden, Rider Linden, Leviathan Linden (not a full list of names at this time – my apologies to those involved whom I have missed).

Additional Work Not Originally In-Scope

  • Direct avatar / object / avatar-avatar interactions (“picking up” an apple; high-fives. etc.).
  • Animations streaming: allowing one viewer to run animations and have them sent via the simulator to all receiving viewers without any further processing of the animations by those viewers.
  • Enhanced LSL integration for animation control.
  • Adoption of better animation standards – possibly glTF.
  • Given the project is incorporating a lot of additional ideas, it is likely to evolve into a rolling development, with immediate targets for development / implementation decided as they are agreed upon, to be followed by future enhancements. As such, much of what goes into the meetings at present is general discussion and recommendations for consideration, rather than confirmed lines o development.

Bugs, Feature Requests and Code Submissions

  • For those experimenting with Puppetry, Jiras (bug reports / fixes or feature requests) should be filed with “[Puppetry]” at the start of the Jira title.
  • There is also a public facing Kanban board with public issues.
  • Those wishing to submit code (plug-ins or other) or who wish to offer a specific feature that might be used with Puppetry should:

Further Information

Meeting Notes

Viewer Progress

  • An updated version of the viewer – version 6.6.12.579958 – was release on Thursday, May 11th.
    • This update includes access to Rider Linden’s experimental attachment point tracking & forwarding to the server feature.
    • It also includes various incremental improvements to handling puppetry, such as support for parsing binary LEAP data from the LEAP script.
  • Avatar attachment point tracking (per the TPVD meeting discussion on May 12th):
    • This allows the tracking of joints (using attachment points) using a script.
    • Using visible attachment points (i.e. those on the avatar , NOT any of the screen-based HUD attachment points) cuts down on the the amount of data having to be be handled at both ends.
    • The speed at which the attachment point movement is read back is such that it could not be exploited to create a copy of an animation with any real fidelity.
    • This is a deliberate move to ensure that animation creators are not left feeling uncomfortable about LSL animation tracking.
    • There is a combined throttle / sleep time elements to tracking attachment points: the throttle limits the number of attachment points that can be tracked over a certain period of time; he script sleep time is designed to allow an animation to move those attachment points forward sufficiently before a further taking record is made. Thus, it is next to impossible to track and record a coherent animation frame.
  • It was noted that previously, joint constraints had been hard coded in C++, but their configuration has been moved into a human-readable LLSD file which can be modified without rebuilding the viewer.
  • Two areas of focus going forward are:
    • Improving the Inverse Kinematic (IK) system within the viewer – something Leviathan Linden is already working on. This will include overall improvements to IK constraints as well as to positioning, with the existing source-code constraints moved  replaced by a further config file – “constraints” here being in terms of joint rotation / movement.
    • Providing .FBX animation file import and Mixamo skeleton re-targeting.
  • The IK work is still being thrashed out (and subject to much more discussion at meetings, but is seen as a priority over other elements of work, such as the animations streaming idea Leviathan Linden had been working on. The hope is that by improving IK, it will play into streaming and “live” animations a lot more robustly and smoothly. It is also seen as a foundational piece of work for further opening up puppetry and animation work.

General Notes

  • It was noted that for animation import, LL is looking towards using / supporting Assimp (github: https://github.com/assimp/assimp), which supports some 30-40 animation formats, converting them to it ownformat for ease of import to multiple platforms. Notably, it supports .FBX and glTF, so it fits with the Lab’s goal of utilising glTF for materials, mesh imports, etc.
  • [TPVD meeting, May 12th] This will not alter the existing internal format for animation. It is just  to allow the import of other formats.
  • It is acknowledged that alongside o that, the Labe will require a retargeting system for animations; although what form this will take is still TBD.
  • The core of the meeting was a general discussion of things that might / could e done in the future, and what technologies LL might look towards.

Date of Next Meeting

  • Thursday, May 25th, 2023, 13:00 SLT.

2023 SL SUG meetings week #19 summary

Posted on by Inara Pey

The White Armory-Silvan Moon Designs, March 2023 – blog post †

The following notes were taken from the Tuesday, May 9th Simulator User Group (SUG) meeting. They form a summary of the items discussed and is not intended to be a full transcript. A video of the entire meeting is embedded at the end of the article for those wishing to review the meeting in full – my thanks to Pantera for recording it.

Server Deployments

  • On Tuesday, May 9th, the SLS Main channel servers were restarted without any deployment, leaving them on simulator release 579747, previously deployed to the RC channels.
    • An issue occurred during the deployment which caused it to be somewhat protracted, but this was overcome without any need for a roll-back.
  • On Wednesday, May 3rd, a new simulator release will be made to the BlueSteel RC channel. This contains configuration changes on to help support the new “Social Casino“.

Upcoming Simulator Updates

  • It is hoped that week #19 will see a new simulator release to the RC channel which contains assorted updates and fixes.
  • No news on when the back-end for PBR Materials will be deployed to Preflight (and Snack?).

Server Deployment Forum Announcements

  • A long-standing aspect of the Tuesday / Wednesday simhost re-starts / deployments is that they have been highlighted through (almost) weekly announcement posts to the Technology > Simulator sub-forum.
  • In recent months this practice has grown increasingly sporadic and for the last multiple weeks, ceased altogether – which has apparently been a deliberate move, LL viewing the dedicated web pages for server and viewer releases as potentially more useful.
  • In addition, LL are looking to try to produce “more substantial release notes”.
  • HOWEVER: the problems here are that:
    1. The forums are a popular resource for users, and the summaries of deployments there do a lot to keep people informed as to what is going on, and how their specific regions might be affected by rolling restarts and updates contained in releases.
    2. Most particularly, while the server release pages provide a list available active and past releases, they do not make it particularly easy to discover information on upcoming deployments, unless you happen to have the actual release number – something what has only previously been made obviously public through – wait for it – the forum posts.
    3. Ergo, it really doesn’t matter how much more informative LL make the release notes if they cannot be found and read in time to understand what any upcoming releases might hold.
  • Given the above – and as Rider Linden noted in the meeting, it would probably be a useful idea for LL to continue to provide the forum posts on upcoming deployments.

Viewer Updates

No official viewer updates at the start of the week, leaving the pipelines as:

  • Release viewer: Performance Floater / Auto FPS RC viewer, version 6.6.11.579629, 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 6.6.8.576972, December 8, 2022.

In Brief

  • HTTP work:
    • Rider Linden is currently working on a server-side update to allow the PATCH method for both HTTP out and in. during the meeting, he raised the idea of possibly adding HEAD to both as well – both of which met with favourable responses.
    • He will attempt to add BUG-231657 “http_response body is blank if no Content-Type header was returned” to the current simulator maintenance update, if it can be fixed in time.
  • KVP work:
    • A simulator update is in progress to de-couple the Experience KVP database from land (i.e. so it will work on land where there is no associated Experience running). It is not clear when this will be deployed within an RC – although it will not be in the next RC update.
    • A request as been made to give the KVP database the same search options as LSD has with llLinksetDataFindKeys(). This is unlikely to happen, with the reason given being that the storage system for experience key-value data and object LSD is totally different, so feature parity between the two doesn’t always make sense / isn’t possible.
    • However, additional work on KVP is on the simulator roadmap, but not work has started on it as yet. This work will likely include: updating the server/software that make that operate; a probable change to the way accounting is performed (e.g. rather than giving KVP users a pool of bytes, the limitation would be by the number of keys, with the overall byte pool increased).
    • This latter point gave rise to concerns about the potential for application breakage for grid-wide applications, particularly those which may expand in their use over time if they are related to a popular product (e.g. a grid-wide teleport system with multiple nodes throughout the grid).  Expect more on this as the ideas are more fleshed-out; for now refer to the last 15 minutes of the video below.
  • There are some reports that BUG-232037 “Avatar Online Offline Status Not Correctly Updating” have worsened on the course of the last week, despite efforts to tamp down on some of the causes. LL are to take “another swing at it”.
  • BUG-233384 “Scripts failing to receive rapid touch_start events under LL viewer” – whilst possibly more a viewer-side issue, was raised on account of it being marked as “resolved” (perhaps as far back as the release of the MFA viewer), and the report closed, but the issue still occurring for some. This led to a discussion on touch events (double-clicks vs. long clicks, games requiring both, the nature of the issue, etc. Those seeing the issue should refer to the video below.

† 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.

2023 week #18: SL CCUG meeting summary – PBR

Posted on by Inara Pey

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.

Notes:

  • 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 6.6.11.579629, 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 6.6.8.576972, 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.

Status

  • 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.