Category: SL User Group Meetings

The following notes and audio were taken from the weekly Bento User Group meeting, held on Thursday, March 3rd at 13:00 SLT on Aditi. For details on each meeting and the location, please refer to the Bento User Group wiki page.

Note that this update is not intended to offer a full transcript of the meeting, nor does it present the discussion points in chronological order. rather, it represents the core points of discussion to Project Bento, grouped together by subject matter were relevant / possible, together with any additional discussion on potential future projects the Lab might be willing to examine for possible adoption in the future.

Skeleton and Viewer Status

Bento viewer work is now focused on finalising the new skeleton, working on bug fixes and investigating hooking the new skeleton into the appearance sliders where is can be done.

It’s anticipated that there will not be any further significant changes to the bones within the skeleton, although there has been some discussion on adding a couple of extra bones into the “hind” limbs. Content creators are therefore being encouraged to develop new test models utilising the skeleton, as available in the current project viewer (version 5.0.0.311861 at the time of writing).

A couple of issues have come to light with the additional bones. In the first, the alternate eye bones weren’t quite lined up with the original eyes, and this is being fixed. There  also appears to be some issues arising from the inclusion of additional spine bones, which is discussed below.

Appearance Sliders

The Lab has been investigating the potential of modifying the appearance sliders (controlled through the avatar.LAD file). This means taking some of the sliders that are based on morphs which deform the default avatar, and allowing them to also be utilised by the Bento skeleton when an avatar mesh employing the skeleton is worn. This work looks “promising”, although the number of sliders means that it is unlikely all of them will be dual-purposed in this way. However, as a part of this work, the Lab will be addressing the slider bugs which have been reported against the latest Bento skeleton as well.

Vir discusses the current status with the Bento skeleton and project viewer

Attachment Points

Some additional attachment points were added specifically for use with the new skeleton, and consideration is being given to adding some more (such as to the new “hind” limbs – which can be used for a variety of purposes other than “just” hind legs, as noted in my last update).  Currently, no clear preference for extra attachment points has been expressed by content creators working on Bento. One group of suggested attach points put forward in the meeting was for rear left leg and rear right leg (upper and lower). rear hip, rear groin, rear left foot, rear right foot, and rear back (for rideable centaurs/saddles).

Responding to this Vir indicated some of these may already be possible, and that others such as those for the hind legs / back are hard to determine as the joints are repositionable,. The suggestion for catering to some of these bones might be to reposition existing attachment point to suit, or the possible inclusion of a new hip root attachment point for the “hind” bones root.

The question was also raised on whether attachment points are lag producing in the same way joints can be. Vir indicated that lag isn’t really an issue with attachment points on their own (although animating them can obviously add an overhead). However, there are other issues with regards to UI / menu management which can make additional attachment points a problem.

For example, there is only a single menu structure available for selecting an attachment point for an item directly from inventory. So the more attachment points added, the more unwieldy the menu gets. The same issue isn’t so apparent when attachment an object from in-world, where the code allows for sub-menus to be added.

Another limiting aspect with attachment points is that there is a hard limit on the total number of joints which can be used (thought to be 255). so if an attachment point was added to every bone, this would likely be exceeded, so things like an attachment point for every finger would probably be out of the question.

Issue Updates

Work is continuing on issues of avatar deformation, but as yet there have been no major breakthroughs.

However, problems appea rto have arisen as a result of the new spine bones. In particular, quadruped avatars appear to “dip” their forelegs and shoulders forward when shifting between certain animations. The precise cause is unclear (this may not even be a new issue, just one that is exacerbated by the new bones), but it could be the result of an interpolation issues, an i-k (inverse kinematics issue) or even some issue relating to bipedal animations (a human avatar tends to lean into something like a walk, and this default movement might be affecting thing). However, the larger the quadruped avatar, the more pronounced the up-and-down motion of the forelegs seems to be.

This problem is further compounded by a problem whereby if the avatar mesh is animated while ignoring the spine bones, then the avatar can end up being distorted following something like a relog; the spine bones must be keyframed in order for the avatar mesh to remain correctly formed.

One possible explanation for this latter issue is that there might be a missing transform in the hierarchy data, such that the weights associated with a joint are skipped, together with any child joints, causing the model to collapse.

As it is, the model in question, animations, etc., are being passed to the Lab so that they can investigate and test things.

Other issues have also been seen with the additional spine bones, which might be down to order of use or correct alignment, as the method by which they have been implemented, in order to preserve backwards compatibility with the avatar skeleton, is complicated.

Continue reading “Project Bento User Group update 8 with audio” →

The following notes and audio were taken from the weekly Bento User Group meeting, held on Thursday, March 3rd at 13:00 SLT on Aditi. For details on each meeting and the location, please refer to the Bento User Group wiki page.

Note that this update does not present the discussion in chronological order; items discussed have, wherever possible and without compromising the discussion itself, have been grouped together to try to present a complete discussion of the topics raised in turn.

New Project Viewer and Bento Skeleton

A new version of the Bento project viewer has been released. Version 5.0.0.311861, dated March 2nd, 2016, includes the updated Bento skeleton, which the Lab hopes will be the final version.  In particular this adds further new bones:

• Four new spine joints: two between mPelvis and mTorso, and two between mTorso and mChest. By default these bones are folded up inside the current spine and will not affect the appearance of the avatar, but like other bones they can be repositioned in uploaded meshes, or animated according to need
• New face bone root: rather than adding extra neck bones, the Lab have added an extra face bone root, which could be used as an extra neck bone if desired
• Three new centre face bones along the mid-line of the face, two on the lips and one on the forehead
• Two new joints for ears, allowing for floppy or otherwise more flexible ears
• An additional pair of limbs, each with 3 joints apiece, and a new root bone to which they are connected. These are named “Hind” limbs, but using the root bone, the can be relocated to be used elsewhere – such as an extra pair of arms
• One new bone for each wing to allow a simple fan as would be used in a bat-type wing.
• Removal of two wing root bones: these were originally included as a workaround for the lack of joint translations. As this is now possible, only a single wing root bone is actually required
• Various bone position changes.

As some of the existing bones have been removed or changed position, this does mean that content made using the original Bento skeleton will need to be updated in order to display as intended. Aditi servers have been updated with the new skeleton.

Vir discusses the new bones and the removal of some bones

The ability to add new spine bones is a direct result of the Lab being able to fix the two issues referred to in my last Bento update, the first of which would crash the Bento viewer if additional spine joints were added, while the second was that new spine bones would break the rendering of the default avatar.

In order for this to work, the new bones have an odd positioning / ordering within the skeleton, so they seem to “zig-zag” (spine 1 is located in chest, spine 2 in the pelvis, then comes the torso, etc). The reason for this was to allow all the original skeleton joints exactly where they had always been located, and to avoid the creation of any zero length bones, with the internal matrix maths (as well as some other programmes) doesn’t particularly like, as Vir explained which discussing the new spine bones.

Vir expands on the new spine bones and ordering

There may be some issues which are causing Blender to incorrectly display the new spine bone positions and orientation. One suggestion for those encountering similar issues is to visualise the bones by setting them to the polyhedral models where it is wider on one end than the other (I’m unfamiliar with blender, so not sure of the precise term for the visualisation) to make it easier to see the orientation of the bones, although this may not work.

Aki Shichiroji, who has experienced the problems, has indicated she’d talk a little more with the Avastar team about things. Certainly, Vir believes working with them is going to require a delicate touch when working with the spine bones in the likes of Maya and Blender, due to the risk of coincident bones.

Next Steps

The Lab intends to freeze the skeleton soon, and those wishing to test it are advised to do so over the next few days. Currently, the easiest way to obtain the latest version of the skeleton is directly from the new version of the project viewer (link above), although hopefully the wiki links, etc., will be updated soon.

There is liable to be one more update to the project viewer once the skeleton is frozen, after which the Lab will be turning attention to the avatar.LAD file, the other major configuration file for the skeleton, and finalising changes and corrections to the shape sliders and potentially adding some new attachment points which can leverage the revised skeleton.

The biggest issue as far as progress the project to initial deployment on the main grid is concerned, is bug fixing. There are still some significant problems yet to be resolved, which are dependent upon understanding the route cause of the problem and having the staff available to investigate them / resolve them:

• Issues with the extra joints, such as the default avatar pose issue (see below)
• The rendering deformations encountered at high altitude
• The general avatar deformation issue seen within the Bento viewer (see here and here for further notes).

There are also a number of more general bugs to be corrected as well.

Overview of the next steps in the project from the Lab’s perspective

Default Avatar Pose Issue

There has been further investigation into the default avatar pose issue which can see quadruped avatars unnaturally crossing or folding their forelegs when shifting between animations (for background see here, here, and here).

It had been thought that the issue was due to the way that scripted animation override systems (e.g. the ZHAO and ZHAO 2) overlay the default server-side avatar poses, occasionally allowing these server-side animation to start playing when shifting between poses as a result of a message timing issue between server and viewer. The suggested solution was therefore thought to be to encourage creators to write AO for their Bento avatars which would utilise the llSetAnimationOverride capability introduced in 2013, which overwrites the server-side defaults with the animations of the creator’s choosing, thus preventing the “wrong” animation starting to be played.

However, more recent testing suggests that the issue can still occur when using llSetAnimationOverride.

A problem here has been that the JIRA specifying the issue and providing information on various tests, etc., carried out to date by the Lab has, not been publicly viewable (for valid reasons), making it hard for other outside the Lab attempting to investigate the problem to understand what has happened to date and report their own findings back to the Lab. Arrangements are now being made to clone the JIRA and make is public to eliminate this problem.

Other Items

Removing Mesh Upload and Display Restrictions

Second Life has always had a number of upload and display restrictions wherein creators were required to include certain joint positions whether or not they were in fact using them (the uploader wouldn’t check to verify whether the positions were actually used, just that they are listed). There were some checks which insisted that if the positions of some of these bones were changed, they all had to be changed.

This obviously limited the number of meshes rigged to bones from different creators that an avatar could wear, because there would inevitably be conflicts between the listed joints in each mesh. The checks themselves date back to when the Lab used a different method for tracking joint positions, and they don’t make a lot of sense today, and so work is in hand to remove them, and should be completed with the next release of the project viewer.

The upshot of this is that once done and available, avatars will be able to wear meshes from different creators, providing the mesh items only list the joints they actually use. This would allow, for example, this will allow someone to wear a centaur avatar from one creator and add a set of wings from another creator without the risk that the meshes would conflict because they list the same “required” joint positions. However, for this to work, it does mean that creators will need to ensure they list only the joints they require in order to offer some degree of “interoperability” between meshes.

Vir discusses the removal of the upload and display restrictions

Using Bones to Animate Hair and Clothes

One benefit from being able to rig and list only the bones which are being used, is that it potentially opens the door to creators being about to use some of the additional bones to animate things like hair and dresses.

For example, as bipedal, humanoid avatars are unlikely to require the tail bones or the “hind” limb bones, these could potentially be used to naturally animate a  mesh gown (particularly one with a long train) or long dresses. Similarly, the additional ear bones might be used to animate mesh hair.

Cathy Foil points-out the potential for clothing and hair makers as a result of the removal of the restrictions

Scripted Methods for Bone Positions

BUG-11407 is a feature request to provide scripted control of bone positions, allowing to an LSL command to pass an array of bone positions to the client to animate oneself, or, with permission granted, to animate another user.

Commenting on this at the meeting, Vir indicated that while such an approach is “interesting”, but due to the scope of things, has been considered to big an undertaking for the Bento project, and would likely have to be considered as a project in its own right. Rider Linden further suggested raising the idea for discussion at the Simulator User Group meeting.

Useful Links

• Project Bento Knowledge Base article – Linden Lab
• Project Bento Skeleton Guide – Linden Lab
• Project Bento Testing – Linden Lab
• Project Bento discussion forum
• Project Bento overview – this blog
• Project Bento updates – this blog