Re: [Empyrean-devel] In the hopes JL is around...

[Joe L. <jc...@cs...>]

On Fri, 12 Nov 2004, Chad Austin wrote:

> Anyone know how to merge geometry in Maya while keeping bone influences
> on the vertices?

I have no doubt that it is possible, although I don't think Maya supports
it directly -- you'd have to do some pretty involved scripting to automate
the process.  To do any sort of modification to skin geometry, you first
have to detach the skin (Skin | Detach Skin), which loses the skin
weights, which is annoying if you have edited them from their default
values.  Maya's workaround for this is to first export the skin weights
(Skin | Edit Smooth Skin | Export Skin Weight Maps), then detach the skin,
edit the geometry, rebind the skin, and import the skin weight maps again.
The skin weight maps are a directory of image files, one for each joint,
that indicate, via a greyscale texture map, the influence of each joint on
geometry vertices.

The problem with using this technique to merge two pieces of geometry is
two-fold:  (1) Exporting the skin weights of the original geometry
produces two directories of weight map images which somehow need to be
merged into one.  Simply adding the image values together would work,
assuming that: (2) The original pieces of geometry don't overlap in UV
space.

So, one way to do the merge might be to:
- Scale both pieces of geometry in UV space so that each occupies one half
  of the texture space.
- Export the weight maps of each piece of geometry.
- Manually merge each weight map image (via the "screen" blending mode in
  Photoshop, for instance).
- Merge the geometry.
- Rebind the skin.
- Import the merged weight maps.

Of course, the success of this method also depends on the weight map
resolution, and maybe other stuff.  A more exact and automated solution
would be to write a custom MEL script to perform the merge
programmatically, although I'm not sure how one would go about this.

                                --=o0o=--
Joe Lee -- jc...@cs...