On Wednesday, December 16th Linden Lab officially announced Project Bento which brings a range of avatar skeleton enhancements to Second Life.
The project has been in progress for the last several months, with the Lab working in collaboration with a number of noted Second Life content creators who specialise in avatar shapes, bodies, and animations. I’ve been fortunate enough to be very peripherally involved in the project myself, with the aim of documenting some of the process involved – and I’ll be providing more on that in an upcoming article.
The blog post announcing Project Bento explains the reason and focus of the work thus:
We know how much work, value, personalization and emotional investment goes into a Second Life avatar, so we have always been careful when considering avatar changes. While we want to make improvements, we also want to maximize backward compatibility. Get ready for the biggest thing that’s happened to avatars in years …
Ever wish you could incorporate a tail, wings, or second set of arms into your avatar? How about having animations for facial expressions and finger movements? Yes, we know that there are some incredibly creative workarounds that give you some of these, but they can’t leverage skeletal animation, so they have been very complex, often fragile, and very expensive in performance and resources both in your Viewer and the Simulator.
We are introducing extensions to the standard Second Life Avatar Skeleton that give you dozens of new bones to support both rigging and animation, and accompanying new attachment points! This extended skeleton, which is fully backward compatible with existing avatars, rigging and animation, gives creators the power to build more sophisticated avatars than ever before.

In particular, Bento sees the introduction of the following Skeleton extensions:
- 11 extra limb bones for wings, additional arms, or extra legs.
- 6 tail bones
- 30 bones in the hands (all 10 fingers!)
- 30 bones for facial expressions
- 2 other new bones in the head for animating ears or antennae
- 13 new attachment points associated with the new bones
The changes involve both simulator updates and changes to the viewer. The former have already been deployed to the grid, being the “secret” update made in week #48, alongside the need validation enforcements for attachment point IDs and to prevent the upload of animations and meshes weighted to invalid attachment points; however, they are not yet active.

This is because the Bento work is still in project status – the announcement is intended to inform people about the work and seek feedback from more creators / animators. This can be given via the Project Bento forum thread, with specific bugs bugs or issues reported by the Project Bento JIRA class.
To try out the new skeleton updates, you will need the Bento project viewer (which sees the viewer iterate to version 5.0), and because the project is still a work in progress, you’ll need to upload any content using the new skeleton extensions to the Aditi (beta) grid – most regions on Aditi should allow this, although some may be in use for other testing and not yet have these updates. Additional documentation is also available, together with notes on testing.
Commenting on the launch of the project, Oz Linden had this to say (from 37,000 ft whilst flying across America!), in recognition of the extensive input made to the project by content creators, which has included modelling and testing the skeletal changes, advising on viewer updates, putting forwards ideas for possible future extensions to the project, and a whole lot more.
Draxtor Despres and I will be covering more of the background story on Project Bento in the near future, including a Drax Files World Makers special on the project in January. Keep your eyes peeled!
With thanks to Matrice Laville and Gaia Clary for the video.