Fitted mesh is here! Find out more at the announcement blog post here.
Today, we are launching an experimental Project Fitted Mesh Viewer with additional collision bones needed to support dynamically fitted mesh garments on all of the avatars. When these changes have been finalized, they will enable garment designers to use the superior capabilities of mesh content creation tools to make garments that adapt to a wide range of Second Life avatars.
Since the introduction of Mesh to Second Life, creators have faced challenges fitting Mesh garments to the Second Life avatar. Because mesh objects are not resizable in as many ways as the avatar itself is, it has been difficult for mesh garment creators to provide garments that adapt to the shape of the avatar in the way that the image-based clothing layers do. While many creators have made heroic efforts to provide products in a range of sizes, and some have collaborated to define a set of standard sizes that work reasonably well for much of the user population, many have found that mesh garments just don't work well enough for their avatars. Mesh garments also don't move with the body parts affected by avatar physics.
Users have developed two approaches to address these problems:
Rigging garments to the "collision bones" of the avatar skeleton (often marketed as "Liquid Mesh"). This works in current Viewers for some body parts, but there are some avatar shape parameters that do not have corresponding collision bones, so garments do not adapt to fit everywhere on the body.
The "Mesh Deformer" project added code to the Viewer to dynamically compute how to modify each garment shape by looking at how the vertices of the avatar were changed from that of the female and male base shapes.
The Linden Lab development team has studied both approaches, and compared their effectiveness, maintainability, and performance. Neither approach completely eliminates the occasional need for an alpha clothing layer to prevent small parts of the avatar skin from appearing through garments, but both work quite well at resizing garments so that they fit the avatar and move naturally with it. While the collision bones method requires the creator to do some additional rigging, we have decided that because it leverages more of the existing avatar shape system it is likely to be the more maintainable solution and to perform better for a wider range of users.
We have posted documentation on the wiki describing the full set of collision bones, including the newly added ones. We invite creators to begin experimenting with creating garments rigged to this new skeleton.
At this time, the new skeleton should be considered provisional and subject to change; we do not yet recommend selling or buying garments rigged to it. Since we may find reasons to improve it during this testing process, and any change to the collision bones will likely break garments rigged before the change, we want to make sure that we have a set of bones that we can all live with into the indefinite future before it is widely used.
Creators and other users who participate in testing can provide feedback by filing Jira issues in the Fitted Mesh project.