Fitted Mesh Kit

Now it gets a bit fuzzy 🙁 However…

You have to take into account that many vertices of a mesh are typically weighted to only one single bone. Actually you “only” have to take care near the joints where you typically get 2 weights per vertex, in some cases 3 weights (as mentioned above for parts of the shoulders) But lets try to start easy (which is already complicated enough)

Vertices with one single weight

Most Collision Bones are immediate children of SL Bones. Hence when an SL Bone moves, then the corresponding Collision Bone follows tightly this movement. Hence it does not matter if you weight a vertex to only one SL Bone or if you weight it only to its corresponding Collision Bone. The character’s animation will work exactly in the same way for both cases (  Remind: This is true only when the vertex is weighted to a single bone ! )

But the mesh will react differently on the apperance sliders! as mentioned above: vertices weighted to SL Bones are influenced by other appearance sliders than vertices weighted to the Collision Bones. So its your decision what you want for a particular area of your mesh: either bone length changes or mesh morph changes (or a combination of them)

Vertices with 2 or more weights

Now it might get a bit tricky. You Still can weight to the collision volumes. This might give reasonable results. In fact in most cases the results are OK.  However you might get curious and maybe you want the area around the joints to keep following the SL Bones. (and have no weights going to the joint areas to Collision Bones) In this case the mesh keeps nicely scaling with the Skeleton Sliders. But i am not sure if this is realy necessary (will update when i played with this a bit more)

So and what about the in between vertices ?

If you weight the joint areas to the SL Bones and the middle of the bone areas to the collision volumes, then you will have to define a weight transition from an SL Bone to its corresponding Collision Bone (the more you approach the middle of the bone, the less weight is put to the SL bone and the more weight is put to the Collision bone). After all the middle of the bone will follow the morph sliders and the joints will follow the Bone length sliders. And the transient vertices will follow a mixture of both. That should work in theory… Now lets go and practice 🙂

The Bind pose matrix essentially allows to define a Pose for each Bone that will be treated as the rest pose. In Blender the rest pose is defined by how the skeleton is arranged in Edit Mode. thus Blender’s Bind pose matrix is always the identity matrix.

I have defined a set of properties which can be created as custom properties of the edit bones. If the properties are available, then the Collada exporter will also use them. If the properties are not available, the Collada exporter will fall back to use the identity matrix (as it did all the time before). The properties are:\

restpose_loc_x (default=0.0)
restpose_loc_y (default=0.0)
restpose_loc_z (default=0.0)

restpose_rot_x (default=0.0)
restpose_rot_y (default=0.0)
restpose_rot_z (default=0.0)
restpose_scale_x (default=1.0)
restpose_scale_y (default=1.0)
restpose_scale_z (default=1.0)

Note: This may be changed in the future as i will propose to add the Bind Pose matrix as an official Blender feature. This might possibly allow us in the future to bind a mesh to arbitrary poses with no extra work.

Important: I found by experiment that for the SL Importer we only need the restpose_scale and the restpose_rot properties. However, since Linden Lab has provided the complete rest pose matrix, i have kept the restpose_loc properties in the blend file, but i renamed them all to “_restpose_loc” (with a leading underscore) to hide them from the Blender Exporter.

You find the properties when you place the armature into Edit Mode. then the values show up in the properties sidebar, and they can be edited in the Object Properties window.