MEL: List All Deformers On A Mesh

Yesterday while working on another script, I found myself in need of a list of all of the deformers on a piece of geometry. It seemed like a simple enough thing to get. After all, it was listed right there in the history tab. Fast forward an hour later and the only method I had come up with to find the data was not going to work for what I needed. So, I reached out to a couple of friends and posted on Tech-Artists.org and got a really great answer. It's still a bit convoluted and I'm bitter that Maya won't just give it to you easily, but it works and it's a relatively small amount of code.

I had been tinkering with using the listHistory mel command but the problem with this is that it returns ALL of the history on the mesh object and not just the deformers. My issue was then, how do I distinguish the deformers from the rest of the data? Without a list of every possible deformer Maya offers to compare it to, there's no way I could find them all.

Solution? `nodeType -inherited`

This command along with the -inherited flag will "Return a string array containing the names of each of the base node types inherited by the given object."

Someone pointed out on the forum that all deformers inherit from the "geometryFilter" base node. With this information we can check through each node in the meshes' history and see if it inherits from geometryFilter. With this, we can return a nice, clean list of all the deformers on a mesh object.

// **********************************************************
// Returns All Deformers On A Mesh
global proc string[] jgReturnMeshDeformers (string $mesh) {

 // List History
 string $history[] = `listHistory $mesh` ;

 // Loop And Check If It's A Deformer
 string $deformers[] ;
 for($node in $history) {
     string $types[] = `nodeType -inherited $node`;
     if(stringArrayContains("geometryFilter",$types)) {
         stringArrayInsertAtIndex(size($deformers),$deformers,$node) ;
     }
 }

 return $deformers ;

}

Download Here: jgReturnMeshDeformers.mel

Another little gem that comes with this method is that it returns them in the current stack order. Bonus!

So far this method is working out very well for my needs. If you find any issues with it or would like to discuss, please leave a comment below.

Tomorrow's post will be about the script I was originally needing this for, which is a procedure to rebuild a blendShape node with only your specified targets. Maya doesn't allow you delete targets from a blendShape node without a hassle, and when it does delete them it leaves empty target indexes and a big mess under the hood. Swing by tomorrow for more about this. Cheers!