Creating Skinned Avatars in trueSpace

Courtesy of Stacee

I should start by saying that for now, skinned avatars have only been tested to work in .cob format, and have only been created here by using the trueSpace program. That being said I cannot vouch for, or for that matter, provide much support for any other method or file format. A cobdump version has not been written to convert a skinned avatar from .cob to .rwx format, so it is not possible to convert them at this time. This may change down the road.

I found that Caligari's version of trueSpace 6.6 did not work for making skinned avatars in AW at the time of my testing. This, too, might have changed. They completely re-did the boning system in 6.6, which rendered it no longer backwards compatible with earlier versions of TS, or with working in AW. To the right is an example of the problems we ran into when using 6.6.

Version 5.1 and 4.2 worked. Version 3.2 does not have a skeleton system (Jointed avatars seemed to be the rage back when 3.2 was new); it only has joints, which will be inadequate for what we want to accomplish.


Starting with the avatar mesh itself:

1) The mesh needs to be one whole piece. It cannot be in separate pieces and "glued" together as jointed avatars are. Supposedly it is possible to make a skinned avatar with parts, but I have not been able to get one to work in AW. So for now, mesh needs to be one whole piece. Curious note: While the mesh must be one whole piece, it is possible to use a mesh with holes in it... missing polygons. Some Poser models I had originally used for testing had these holes or missing polygons.

How it breaks: The avatar acted as though it were all part of the pelvis and moved like one big stiff cardboard cutout. It did not render the separate pieces, eyeballs in this case, in Active Worlds.

2) There does seem to be a limit on the number of polygons a skinned mesh can have in AW. We tried the Poser models that had 35,000+ polys and they didn't work. However, 15,000 did. Unfortunately, I do not know the actual limit. Bear in mind: though the limit does seem to be high, the same rules apply as they did with Jointed: More polygons, the more the computer has to render, the more it will cut down on frame rate and prolong on download time (if you don't manage to crash the browser first). While Skins will need more polygons than Jointed to move in a smooth fashion, it should be kept as low as possible. The one avatar I last worked with had about 4,200 polys and moved very nicely, but this was for test purposes alone. I'm aiming for 5,000 polys at max, but again, it is not a solid rule. If you are between 1,000 and 5,000, you're golden.

3) The mesh requires at least two textures or colors to work in AW. Go figure! lol This one took awhile to figure out. So long as there is more than one, you should be okay. If polygons are painted with any degree of transparency less than 1, the avatar will break. I did not try using masks, but I have a feeling the same rule applies.

How it breaks:

1. If only one texture, or one color, is applied to the whole avatar, it does the cardboard cutout again.

2. When painting the eye slots invisible (transparency), I got the result to the right. Scary stuff! Results seem random. So unless you are doing a Frankenstein test, please, think of the avatars.

4) A name must be applied to the mesh. I couldn't find a default one that Nelson (Hamfon) made for the skin, so I gave the mesh the name aw_back,7. Why? It was the name that somehow accidentally made it on the first working avatar, so I figured 7 must be a good number. ;)

5) Make sure that the axis for the avatar is at 0, 0, 0 and that it is lying in the 90 deg, 0 deg, 180 deg position, which is the standard for saving jointed avatars in. Yes, the avatar is built with a skeleton when it's lying on it's back. Once a skeleton is attached, the mesh can no longer be rotated in trueSpace, which is why it is done this way. If the axis for the avatar mesh is not put in the position as stated above, the avatar is in danger of breaking, most visibly where joints bend.

How it breaks: You will end up with horrible mutation of the mesh at all the joint areas. The avatar will appear as though it's being stretched like weird taffy.

On to the Skeleton:

1) When building the skeleton, the only bone that is most important is the pelvis. The pelvis has to be the base. TS doesn't seem to put the skeleton into a hierarchy like we are used to with jointed avatars. Nonetheless, as long as the pelvis is the base of the whole skeleton, all is good. I usually start from the pelvis, and start building the skeleton down one leg, then another, then up the back to the head, and finally each arm. It doesn't matter which way you go to build, but it's good to finish one limb before going to another.

2) Bones are named just as the body parts of a jointed avatar. I list here the bone tags of a simple skeleton:

     aw_pelvis, aw_back, aw_neck, aw_head
     aw_lfhip, aw_lfknee, aw_lfankle
     aw_rthip, aw_rtknee, aw_rtankle
     aw_lfshoulder, aw_lfelbow, aw_lfwrist
     aw_rtshoulder, aw_rtelbow, aw_rtwrist

Below is a picture of what the avatar will look like in trueSpace as you are working.

Skinned Avatar

Click image for a larger version.
(opens in new window)

3) The joints that join bones together also need to be named. They start with the "aw_" prefix and are followed by the names of the two bones they are joining.

     Ex: aw_back_lfshoulder

List the bone that is higher in the hierarchy first. Bizarre note: trueSpace 4.2 seems to have a bug where it sets a limit on the number of characters a joint or bone can have. Therefore, the joints aw_lfshoulder_lfwrist and aw_rtshoulder_rtwrist cannot be written in this version because they are too long. Previous and subsequent versions of TS do not seem to have this limitation.

4) Once all bones and joints are named, and they have been positioned where you want them inside the avatar mesh, make sure the axis for the skeleton is at 0, 0, 0, and you can now join the mesh to the skeleton using the button in TS for that purpose. Name the avatar aw_avatar_v3

Note: It will still be possible to position bones and joints after joining the mesh and skeleton, but make sure this step is completed before you go on to assigning vertices to bones. Otherwise, if a bone or joint is moved later, all information for the vertices' association will be lost and you will have to re-do it for the entire avatar.

5) trueSpace will automatically assign vertices to the closest bones and joints in the skeleton. This is not often how you would assign them, especially with regard to those around the joints. No vertices should be assigned to joints. AW does not currently translate that information. All vertices in a mesh must be assigned to bones in the skeleton. Any assigned to joints or having no association to anything will end up having a mind of their own and not move with the rest of the avatar. On the right is an example of what I mean. One vertex was not attached to any bone and it became a free wanderer in Active Worlds.

To find out which vertices are attached to a specific bone or joint, use the "Edit Muscles" tool. The name deceived me; it took me awhile to learn that this controlled vertices and not muscles. This tool allows you to click on a bone or joint, and will highlight the vertices joined to it. Often times, you will want to change these mappings. Left clicking on the tool button will bring up a box that allows you to add or subtract vertices from a bone, by single vertex or by lassoing and grabbing a large section at once. Very helpful tool.

This part can be painstaking at times, depending on the complexity of the avatar... another reason to keep an avatar as low on polygons and vertices as you can. As I said, if you later move a bone or joint, all the information you did for mapping vertices to bones will be lost and set to the default it originally gave, so make sure you've positioned your skeleton exactly as you want before assigning vertices to it.

6) As for adjusting joints and their angles of mobility and motion in trueSpace... don't, unless you are feeling bold and adventurous. When I tried to set or define joints and their angles of motion, it seemed to create bizarre results in AW, but it hasn't been fully tested.

On a final note: trueSpace will save the avatar in the default position of the skeleton. For instance, if you had your avatar lying with arms out to the sides before the skeleton was put in, then add a skeleton, and finally position the arms down, it will save it with the arms up. It saves that as the default position. This is good and bad. Good because it allows you to move the limbs of the avatar around in trueSpace while you work without fear of it being saved in some strange way when you are done. Bad because sometimes you'd really like to change the position it's saved in... who wants an avatar with arms flapping out like a bird?!

Attaching vertices such as those under the arm or around the legs is much easier when the limbs are spread out, but if a skeleton has that as its default position, then it is saved that way in the final avatar. I've tried finding a work-around for this, and haven't come up with any very good solutions. This, along with the highly touchy system of moving limbs on a skeleton and a few other tricky problems, is among the reasons an alternate program is being considered to make the process of skinning avatars easier.

Do not try to convert the .cob to an .rwx. I know, some of us love rwx. We do so much editing in .rwx. But the versions of cobdump we have at present cannot handle converting skinned avatars. It has to be used in a zipped .cob file format for AW. Make sure you put avatarname.cob when calling for it in the .dat file

Well, there it is. Not for the faint of heart, but I hope it helps someone out there. If you want to test and try in other programs using the guidelines that are set out here you are more then welcome to.

Assistance for creating skins, whether artistic or technical, is not available at this time.


We Wanna Hear From You!

If you would like to write an article for the newsletter or have a project you would like to share with the community through this newsletter, please contact us ( to find out more about participating.

Send us feedback! E-mail comments to