#SL Content-Mesh UG Week 2

The big news for mesh is currently Qarl’s Mesh Deformer. It is out and now in several Third Party Viewers (TPV) and a Linden Lab project viewer. I had to figure out where it is hiding. When I found it found it I had a ‘D’oh’ moment. The download link is in the summary. The feature works well enough in TPV’s. There are some problems.

Deformer Complcations

Part of the idea of the Mesh Deformer was to eliminate the need for us to change our shape to fit the clothes. The clothes would change to fit us. But, we are finding it is not that simple. Things like mesh shoes mess up unless one changes their foot size away from the 0 size many of us use. At 0 size the distorted foot distorts the mesh shoe. So, some are thinking that a switch is needed to tell the mesh deformer to deform or not. We could then mark the shoes No-Deform.

There are some other problems too. As the avatar gets big or small and the shape settings move toward the extreme values we see poke through and bumpiness. In these cases we need more or less deformation. Some have suggested a slider to set the amount of deformation.

Foot Size

Changing foot size now may not be that much of a problem. Most of the shoes I wear now have an alpha layer and it doesn’t matter what size my foot is. So, I could probably change my foot size to something that avoids distorting the avatar to try and fit my foot in a shoe. That could correct the problem with shoes.


The avatar mesh we have now is not all that great. At the time it was created it was awesome and efficient. But, we have greatly improved the appearance of avatars since then. Now the avatar mesh is holding us back.

It is this avatar mesh and its odd, my word, polygon arrangements that create problems matching the polygons in mesh clothes to those of the avatar. If you have ever made underwear or short shorts you know the problem you have making them look right in the crotch area.

Qarl based his deformation of the mesh on what the nearest vertex in the avatar is doing. We often have more vertices in our clothing than the avatar has. So, several vertices in the clothing may be controlled by a single vertex in the avatar mesh. This is causing some problems. We see it as bumpiness in the mesh when it distorts.

I made an image to show what is happening. The center image (A) is the beginning scenario. The avatar is represented by the 8 vertices in the center (yellow). Mesh clothes are represented by the 32 vertices on the outside (green).

When the nearest vertex in the avatar controls the vertices in the clothes the mismatch of vertices starts to create some problems. The 8 vertices to 32 verties ratio mean each avatar vertex is going to control 4 on the clothes. In my image everything is equally spaced. Of course in practice that is not the case. The avatar’s vertices are not evenly spaced nor are those in clothes likely to be. So, in practice the situation will be worse than what I show.

In the left and right images (B & C) you can see what happens when an avatar vertex is moved. The space between the clothing vertices and avatar vertex is the same in all three images.

In ‘B’ I show the 3 avatar vertices that form a smooth surface in the smaller rectangle. The large rectangle shows the clothing vertices that are controlled by the 3 avatar vertices. You can see the problem that starts to set in when all the vertices are not moved uniformly. This is what causes the bumpiness.

There are ways around this problem. One could average the control vertices and/or the clothing vertices. That would help in some situations. It would also make problems for things with sharp edges, like sci-fi body armor.

The challenge in SL is figuring out how to make something that works well in all situations. That is probably not possible. So, a no-deform switch or a slider control to vary the amount of deformation may be needed.

Test Clothes

Now that we have the deformer, creators can make clothes based on the idea they will be used with the deformer. Once we have those clothes we will start to know how well this current implementation is working. From there we may be able to see a direction to go.


Charlar is limiting the discussion about the Deformer in the Creation/Mesh group. It makes sense as the Lindens there are not working with that level of viewer construction. Oz Linden’s open source user group is probably more appropriate.

For most of us the SL Forum is going to be the discussion area. Especially since this is mostly a non-Linden project.

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