Rigging & Weighting

These vertices are not assigned to any of the Deforming Bones (unweighted) or assigned with a total weight of 0 to one or more Deforming groups (zero weighted). These vertices only move along with the movements of the mPelvis Bone.

When you pose any other bone in Blender then this appears like the unweighted vertices are simply “glued” to their RestPose Location (See image)

 

Note: Avastar does not allow to export a mesh with zero-weighted or  unweighted vertices. The original reason for this was that the SL Importer would not accept these meshes either.
But nowadays the SL Importer will accept the mesh for import. However unweighted vertices will disappear when you wear the mesh, while zero-weighted vertices behave like in Blender

In Blender you can assign as may weights as you like to one single vertex. But in SL (and OpenSim as well) the maximum number of weights per vertex is limited to 4.

The Avastar Exporter will automatically reduce the number of weights per vertex. It simply removes the weights with the smallest weight values until the number of weights is 4 for the vertex.

Note: In SL it is unclear what exactly will happen. We do not know if the first 4 weights are preserved or the 4 weights with the highest values are preserved.

Duplicate vertices are 2 or more verts which occupy the same location in 3D space. While this is not necessarily an error, and sometimes it is actually wanted (for example when you use an efge-split modifer),  it is still important to avoid duplicate verts wherever they appear unintentionally to avoid potential texturing issues and weighting problems.

Note: In SL there is no special signature for unwanted duplicates, so you have to check this on purpose if you want to avoid them.

During parenting a mesh to an Avastar rig you can enable an initial Weight copy from all visible siblings to all bones of the parented mesh. In the image on the right you see the armature (yellow) and the shirt(semi transparent) selected. Initial weight copy will project the weights of the upper body into the weights of the shirt. For more detailed information see the Reference guide
Binding(Assign to Armature).

Avastar supports 2 different skinning patterns for animating an SL mesh character:

• Via weighting the mBones
  (also named Classic Weighting)
• Via weighting the cBones
  (also named Fitted Mesh Weighting).

Avastar can pre configure a Mesh to use either of the weighting patterns. For details read the Skinning section.

While working on the weights of a mesh in Weight Paint mode you can do a weight copy on a bone by bone base. The details are described in the weight copy tool reference below.

Note: The Selector in the Mirror Opposite Bones button is new with Avastar-1.3

If you want to copy from another bone, then you must ensure that you have selected exactly 2 bones, where the source bone must be selected first while the target bone is SHIFT Selected second (so the target bone becomes the active bone!)

Note: The target bone’s weights will be entirely replaced by the weights from the source bone, not added or merged!

If you want to mirror copy then you only have to select the target bone(s). You can select a set of bones. Avastar will perform the mirror function on each selected bone.

 

New in Avastar-1.3: You now can specify if your copy shall use Topology mirror or Vertex Mirror. Please be aware that topology mirror can only be used when the mesh is not symmetric! For perfect symmetric meshes you will always use Vertex Mirror.

A common pitfall with Weight Copy happens when your mesh is slightly asymmetric. on the next image you see an example:

The boots look pretty much equal, so you have the impression that a weight copy should be no big deal. But actually i have moved the left boot slightly out of symmetry, so all vertices have a small offset from perfect symmetry. And you can not see this slight asymmetry by just looking at it.

Lets assume you have carefully weighted the left boot and now you want to mirror copy the weights from the left ankle to the right ankle.

So you will select the right ankle bone, and then perform a Mirror from Opposite Bone. But you end up with the weights not mirrored. In the image you see the weights are not copied to the right ankle as expected, but the weights remain on the original vertices.

Whenever you see this happen you can be sure that your mesh is not exactly symmetric. In that case you can try a topology mirror copy, but unluckily this has its own pitfalls as well…

So lets try to do a mirror copy with topology mirroring enabled (select Topology in the selector right to the Bone Mirror Copy Butto). In my case i ended up with a very strange result as you can see in the next image.

The problem with topology mirroring is that the used function needs a more complex mesh to identify the mirrored vertices. I have not fully understood how it works, but apparently it does not work for low polygon meshes, hence Topology mirroring is in general not suitable for game engine development.

Each classic mBone is related to a corresponding fitted mesh cBone. Hence when you select any of the Deform bones the tool knows which is the counterpart bone according to the table below.

Each time when you call the tool, the weights of the selected Bone(s) will be swapped with the weights of their corresponding counterpart.

This is obvious: The weight groups of all selected bones will be reset (made empty). You may want to do that when you decide to restart a bone weighting from the beginning.

If you want to copy weights from other meshes (weight sources) to a mesh (weight target), then all source meshes and the target mesh must be siblings of the same armature. (all meshes must be attached to the same armature). All currently selected bones will become Copy targets in that case.

Note: Only visible weight sources are taken into account. Hence at least one weight source (mesh) must be visible.

Note: If you want to do a full weight Copy, then you only need to select all SL Bones (the blue ones) as seen in the image to the right.

Note: Custom meshes can also be used as Sources for a Weight Copy, provided they are siblings of the active Mesh!

Note: the topology of the source meshes and the target mesh may be different!