With this article I aim to provide IMVU creators with tips on skinning a fashion item.
The original avatars had a physique modifier. IMVU now has a reference file with a skin modifier. This is what you need for this tutorial.
- Open 3DSMAX (2016 & up) and open the avatar file and check if the avatar has the ‘skin’ modifier applied.
- Merge your clothing mesh into the scene (File – Import – Merge). You may choose ‘Scene materials’ if you get a warning of a material conflict. And apply the multisub material that is used for the avatar onto your clothing mesh. You will need to add additional slots on that multi sub material for your clothing mesh. Id’s should follow up each-other.    …    etc.
- If you had already mapped and assigned material ID’s to the clothing mesh you created you may choose to use the material information of the file you are merging. (just check the meshes in your scene if it still contains the right texture information after merging)
Select the female.NakedTop and call up the ‘object properties’ window (right mouse click) and choose ‘Display As Box’. This will ‘hide’ the item by showing a rectangular frame instead. This will lower memory use of the program and makes it easier to focus on your clothing mesh. You may do this with other parts of the avatar as well.
Select your clothing Mesh and use the ‘xView’ (beneath the + sign at the left top corner of your window; ‘front’, ‘left’, ‘top’, or ‘bottom’) to check your mesh up for any errors like a.o. ‘open edges’, ‘multiple edges’, ‘isolated vertices’, and ‘T-vertices’. Open edges should only appear on the outlines of the mesh (end of sleeves, intended holes or cuts, neck, bottom of the shirt) and preferable nowhere else. Click the green ‘Click here to update’ notification at the bottom of the window.
This will show if there are any errors that you should try to address before proceeding to further steps.
T-vertices are vertices that can cause difficulties with skinning. By using ‘xView’ you can identify where they are and resolve them by selecting a green vertice and a logical nearby one to ‘connect’ them. (Modify – Edit Vertices – Connect). Do that with all the green vertices.
After the mesh has been optimized and errors limited it is ready to build a texture mapping. Mapping is a skill on it’s own and is not part of this tutorial. Map the mesh and apply the new material to your clothing mesh. Make sure all the polygons of your mesh get the right ID applied.
If your clothing mesh already has a mapping you can skip this step.
When a texture mapping has been applied to the mesh it is time to inherit the ‘skin’ information of the IMVU avatar onto your clothing mesh. First select your clothing mesh. Then apply a ‘Skin Wrap’. (Modify – Skin Wrap).
Before doing anything else, set the drop down button beneath the ‘Deformation Engine’ to ‘Vertice Deformation’ with a ‘FallOff’ setting of ‘0.001’. Then scroll all the way down and check ‘Weight All Points’. Uncheck ‘ Blend To Base Mesh’ that is in the middle of the scroll-able field. If checked it will fix the clothing mesh stuck to the avatar body which is in most cases not desirable.
Use the ‘Add’ button under ‘Parameters’ to add parts of the original avatar that your clothing mesh should be weighted to. In case of a (long) sweater it is the female.NakedTop and female.NakedPelvis that should be added. Then click on the ‘Add’ button again to finish adding avatar parts.
Then hit the button ‘Convert To Skin’. Your clothing mesh has now a skin applied.
Now it is time to move the slider to see how your mesh is moving along with the avatar. If you wish you can select avatar body parts and uncheck the ‘Display As Box’ in the ‘Object Properties’ window. (Select Avatar Mesh Part – Right Mouse Click – Object Properties.)
Closely inspect your mesh for any skin distortions. Unpleasing folds or bumps. The next step is to edit the skin that was applied to smooth it out as much as possible. (Don’t aim for perfection, even high end video-games aren’t perfect in skinning or physiques).
In the Modify tab, click the ‘Edit Envelopes’ and check ‘Edit Vertices’ under ‘Parameters’. Then scroll all the way down and call up the ‘Weight Tool’ window. It is the little icon with a tool.
You can select any vertice or select a few and use ‘Loop’ if you want to add vertices running along an edge loop. A list of bones these vertices are assigned to appears at the bottom. When you select one it will show you a colored overview of how the skin is affecting the selected vertices. Play around with different bones and the blend button.
Last steps (that involves a lot of back and forth editing between your MAX file and the IMVU client). Return the slider to ‘0’ if it was not there already. Then select the master root and export that file. Then export all the meshes you need for your product. All avatar body parts that you need (if you altered the basic shape before making your clothing mesh – which is likely) and your clothing meshes.
Then assemble the product in IMVU and test out your skinning. With both MAX and IMVU editor open tweak the skin until you feel satisfied.
That was my first tutorial. Made with love for my fellow IMVU creators. I hope it helps you along.