[Bf-funboard] Some skinning feature ideas

Tony Mullen tony.mullen at gmail.com
Tue Apr 3 02:40:11 CEST 2007


Hi,

> It's not the ideal access to the feature, but if you make the armature
> the Armature Parent of the mesh, one of the vert group options that pops
> up is "Create Names" or something like. Choosing that option creates
> empty vert groups with all bone names.

Ah, I'd forgotten about that.  Actually, I found another solution.
After pressing the W key with all the desired bones selected, you can
simply press "clear" in the weight paint buttons.  This is pretty much
what I was looking for.  I hadn't thought to try using it with
multiple bones selected, but it seems to work.

> Actually, this would be something to put in the Mesh Scripts menu,
> accessible right on the 3D view header. Shouldn't be that hard to write.

You're right. It should be pretty simple.  If I get a little time soon
I'll see about writing something like this.  I've been meaning to for
a while...;)

> On point #2, I'll have to check, but I don't think that a vert weighted
> at 1 for two different groups gives the same behavior as one weighted at
> .5 for two groups, nor should it.

I wasn't sure either, but after Bassam's comment and a little testing,
I think this would give the same behavior, so long as no other bones
are influencing.  If any other bones are influencing, then you're
right, the two situations would yield different results.

> 2) vertex weights are normalized for bones already- you can assign a
> weight of one to each bone and they mix fifty fifty- no "greater than
> one" or "less than one" weights are allowed to a vertex. If you assign a
> vertex a weight of 0.1 to one bone, and no other bone influences, it
> will have an effective weight of 1.

Ah.  So it seems.  In this case, maybe my confusion stems from the
fact that the paint colors do not reflect the true influence of the
bone on the mesh.  In fact, they are kind of arbitrary in themselves.
Looking at the paint color for a specific bone tells you nothing at
all about how much influence that bone will have on that vertex,
without knowing all other bone weights (and furthermore there is no
simple, straightforward way to access this information of how many and
which bones are exerting how much weight on a vert).  I guess I might
suggest something like a "Display Normalized Values" button or
something.

In short, what we currently have is normalized influence values
coupled with non-normalized paint color values.  I think having some
paint options (which would also hold true for manually assigning
verts) would be helpful here.

> Really?  Try painting weights in maya sometime.  It's hell.

I haven't dealt with this stuff in Maya, but don't offhand see why a
normalized paint function would need to/should operate over the entire
mesh.  But it does seem potentially desirable that if I spray or
assign a value of 1 for bone X onto a vert, I have the option to mean
that I want X to have 100 percent influence over that vert.  The other
groups' influence on that vert would be reduced to zero, but this
needn't (shouldn't) change values for any other parts of the mesh.

For example, let's say I've got a fingertip and I know that I want it
to be deformed only by the fingertip bone, but for some reason it is
currently being very slightly influenced by some unrelated bones.
Currently, I have to hunt down all those potential offending bones,
and there may be many with small influences, if I wasn't careful early
on.  It seems desirable that I should be able to select the fingertip,
assign a value of 1 for that bone, and leave it at that, knowing that
this 1 *really* meant 1.  All other weights on those verts would be
automatically reduced to zero.

So I guess my proposal would be to have two additional toggle buttons
on the Weight Paint tab, one that said, for example "Display
Normalized Values" and one that said "Assign Absolute Weights".  These
options would also hold when assigning weights manually in the Vertex
Groups tab.

Tony


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