Project Bento User Group update 6 with audio

Project Bento extends the avatar skeleton, adding a significant set of bones (e.g. 30 for the face, 30 for the hands Project Bento - extending the SL avatar skeleton

Project Bento – extending the SL avatar skeleton

The following notes and audio were taken from the weekly Bento User Group meeting, held on Thursday, February 25th 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 the audio excepts are not necessarily chronological, one to the next. Items such as wing bones were discussed at a couple of different points in the meeting, but the comments have been drawn together in an attempt to present a complete discussion of the subject; however, the subjects within each audio extract are provided in the order the discussion proceeded (i.e. the initial part of the discussion on wings is presented first, and the that later additional discussion presented at the end of the audio).

This was a short meeting, with the primary topic of conversation being finalising the Bento  skeleton in terms of additional bones and bone sets, following the recent survey (see my week 4 update).

Additional Tail / Limb Bone Sets

Vir indicated that he, Cathy Foil and Matrice Leville have been discussing a couple of ideas. The first is to cull some of the additional wing bones to produce a second set of “tail” bones, which could then be used for a variety of purposes, including creating additional limbs, or a new limb and additional animation options on the existing tail, etc. This approach would see each of the tails have 5 bones, compared to the current tail having six bones.

The second idea revolves around creating a pair of new limb bones using bones taken from the wings, and which would share the same mPelvis anchor point within the skeleton along with the existing tail (which would retain its existing 6 bones). This would simplify the creation of hind legs on avatars, allowing the tail to be moved”backwards” with them. At the same time, it would mean the additional limb bones could also be used for other purposes, if required.

This sparked a discussion on what might be the optimal approach to additional bone sets, naming conventions and whether any additional bones were in fact required, given there is now the ability to translate bone positions as well as rotate them. Vir agreed that naming does need to be considered, as that using terms like “tail” should mean the bones are limited to that particular use.

Concern was also raised on whether adding additional bone might add to the Bento time frame and if there might be other impacts. With regards to the latter, Vir indicated his hope is to run a stress test once the skeleton is finalised.

Other suggestions have been to simple add further bones to existing sets – such as with the hands, as suggested by Gaia Clary in the forums, although this has seen been seen as perhaps not as required as originally thought. Vir also reiterated that any additional limb bones could be used for arms as well as legs,

Medhue Simoni demonstrates an alternative use for "wing" bone sets, which he uses to animate his elephant's ears

Medhue Simoni demonstrates an alternative use for “wing” bone sets, which he uses to animate his elephant’s ears

There has also been some discussion on the forum concerns limitations within the wing bone sets, which could be solved through the addition of wing “fingers” which would allow better animation of bat / dragon wings, with an explanation on how provided by Teager, who also explains the differences involved in animating such wings and those of birds.

Overall Status for Skeleton

In terms of any consensus for additional bones, it is Vir’s view that there is slightly more interest in having additional limb bones rather than a “two tails” approach, together with additional bones for wings (which could also be used for things like ears, etc.).

Vir will be taking this into account when defining the final skeleton, which he hopes to have available for people to review and test by the next meeting. However, he did warn that the overheads in getting the work completed, tested and signed-off might impact on this target, but it is one he’ll push for.

Issues Update

Additional Spine Joints

Vir is investigating problems with adding extra spine joints in the avatar, and has come across two issues. The first is that doing so can cause the current version of the Bento viewer to crash, although he believes he has a fix for this problem. The second, and more serious issue, is that additional spine joints, whilst working for mesh avatars, it will break the rendering of the default avatar. This appears to be a complex issue, and Vir isn’t confident it is one which might be fixed in time for the initial Bento deployment.

Avatar Deformations

A rather squished Dan Linden

A rather squished Dan Linden

Dan Linden continues to try to hunt down the cause of avatar deformations (BUG-11157). It has been noted that this is a complex problem, involving multiple factors – something which makes it hard to reproduce in a consistent manner. Following investigations, as I’ve previously noted, one causes appears to be scripted deformers which can have an adverse impact on avatars, in that they can continue to run when changing from one avatar to the next, causing the newly worn avatar to deform when seen by others.

However, the issue seems to be slightly broader than this, in that it appears a deformer used by one avatar can appear to impact another avatar when seen by others, whether or not that avatar is using the Bento skeleton.

An example of this occurred during the meeting, when Dan Linden, who was using the default avatar skeleton, arrived just as someone else was swapping avatars using deformation scripts. The result was that for myself and another attendee at the meeting, Dan’s avatar appeared deformed when viewed using the Bento viewer, while others who arrived a little later saw him normally. However, even the circumstances under which this situation occurred seemed to vary when put to a short test following the meeting, highlighting the fact that determining precise causes remains difficult.

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