Weight Paint Bone Selection vs Vertex Group Selection

Question

Trying to learn about weight painting. I have a fairly complex armature (human skeleton, imported from Fallout game) and corresponding clothes that I would like to weight paint.

I weight paint mode I can select bones in the armature with RMB on the bone in question. But some of these bones are very close to each other, is there some other way I can select them? I can't find them in any panel?

I can find the vertex groups however. But I'm not sure selecting the vertex group called f.ex "right_arm" is the same as selecting the bone called "right_arm". Selecting the bone, seems to also select the vertex group, but not vice versa? Ie, if I do "select right_arm vertex group and then rotate it, I don't get the expected result (the right_arm bone doesn't rotate). But it's all good if I RMB select right_arm bone in the 3d-window.

What am I doing if I have selected f.ex right_arm bone, and then I select left_arm vertex group and then I start weight painting? I can't just wrap my head around that...

Answer 1

When I have this kind of doubts, I generally build a simple armature (2-3 bones), a simple object and try and experiment the behaviour I'm not sure about.

Anyway: the best way to select bones close each otheror overlapping is to separate them into different bone layers and turn on and off the needed layers.

The weight is an attribute of a vertex, relatively to a vertex group, which belongs to a mesh, so when you do some weight painting you are workng on a mesh, so if you select a new vertex group the weight painting will be relative to this latter vertex group, no matter which was the last selected bone in the armature.

When you add to a mesh an Armature modifier and select as object your armature, every time you move a bone in pose mode Blender will search in the mesh if there is a vertex group with the same name, and will move the belonging vertices according to all weights in all vertex group.

This relationship is often set by the shortcut Ctrl+P (with automatic weights).

An useful and often unknown tool is: if you select your mesh, enter edit mode and select a weighted vertex, in the right properties panel (N ) you can find the vertex weights tab, which tells you all the weight assignements of the active vertex.