Mesh Deformer for tailoring mesh clothing

BEFORE YOU COMMENT

Please read this description carefully. Comments should be relevant to the scope of the issue as stated here, and not about:

* Mesh in general
* Mesh objects not designed against the unmodified avatar shape this uses as the base
* Deformation on custom avatars

Those are fine topics, but should be addressed on the Viewer Forum
(http://community.secondlife.com/t5/Second-Life-Viewer/bd-p/SLViewer), not here.

problem: when wearing mesh clothing in second life - modifying the body shape of the avatar causes the clothing to no longer fit. making the avatar fatter causes it to protrude beyond clothing; making it thinner causes the clothing to hang in space away from the avatar.

solution: deform clothing meshes to match changes in avatar shape.

for each avatar type (male, female) we'll choose a template shape - this will be a generic form for the avatar and will be specified by an exact set of shape parameters. when modelers create clothing - they will tailor their item to exactly fit this template shape.

when a user modifies his avatar shape (making it thinner, or more muscular, or fatter, etc.) the exact changes from the template will be determined: for each vertex on the avatar mesh, a vector will store the change in position. this set of vertices and change vectors will be used to create a deformer, which when applied to a clothing mesh, will deform that mesh so that it fits the new avatar shape.

FAQ:

Q: will this deformer work on any avatar mesh (dragon, robot, etc) or only the default male and female avatars provided by SL.

A: only the default SL avatars will be supported.

Q: will the deformed mesh clothing match all the sliders controlled in the avatar editor?

A: yes.

Q: will users have control over layering of multiple mesh clothing items?

A: no. this project is to address ONLY the issues caused by changing the avatar's shape.

Q: will users have control over offset or thickness for mesh clothing?

A: users will not have this control. clothing designers will be able to control this when modeling the clothing on the template avatar.

Q: will manual adjustments be possible? required? or will deformation be fully automatic?

A: the user will make no manual adjustments. the deformer will be fully automatic.

Q: when does the deformation take place?

A: when the user puts on a new piece of clothing - and when the user modifies any of their avatar shape parameters.

Q: is the deformation computed on the client or the server?

A: it is computed on the client.

Q: what dependencies might this have on the server side?

A: a new boolean variable will need to be added to the mesh asset. the variable indicates whether this mesh should be deformed or not.

Q: will mesh clothing deform dynamically to match avatar physics wearables?

A: deforming with avatar physics was not part of the original specification of the project - and may possibly entail a large amount of development work to do efficiently. however, LL has shown keen interest in having the deformer work with physics - so we are examining the costs.

Q: what about automatic skin weights?

A: that work can be done independently of this work - so i think it's best to create a separate (mini) project for it.

Q: what happens to already existing rigged mesh wearables?

A: the default behavior for meshes which were created before the deformer will be to NOT apply the deformer. (this is for backwards compatibility - so that any meshes created prior to this work are not broken.)

Q: how will this deformer work with skirts?

A: the deformer will not treat skirts any differently than other clothing types.