topic Re: Multiple weight maps like skinCluster in Maya Programming Forum

Multiple weight maps like skinCluster

jmreinhart — Sat, 23 May 2020 19:00:03 GMT

I have a custom deformer that is working great. But I want it to have any array of weight maps like a blendshape or skinCluster node.

I've seen Chad Vernons example of this, but his deformer uses a doubleArray and mine uses a multiFloat. I don't think I can switch to using a doubleArray and use his method because my deformers behavior requires you to be able to choose which verts are the deformer set.

Correct me if I am wrong but the doubleArray method requires you to deform all the vertices.

Also his method doesn't show the results of the painted weights until you change the paintIndex, which is quite annoying.

The skinCluster node seems to be doing exactly what I need, but I have no idea how it does it internally,

Any help would be greatly appreciated.

Re: Multiple weight maps like skinCluster

jmreinhart — Sun, 24 May 2020 11:01:13 GMT

So I think that if I use a method like the MFnWeightGeometryFilter.getWeights and setWeights that will work perfectly. Does that method just loop through the elements using the setLogicalIndex?

Re: Multiple weight maps like skinCluster

jmreinhart — Sun, 24 May 2020 14:50:59 GMT

So I used that method and it definitely works, but I'm not satisfied with the speed. On a mesh with 10,000 verts it takes more than a full second to switch weightMaps, which is acceptable but if I use this method when I make the paintWeights interactively update it will be way too slow.

Right now I am using the MItGeometry to know how many components we need to copy weights for. If I could limit the copying to only the ones in the deformer set that would be phenomenal. But I don't know how I could use this MItGeometry method to get that, outside of the compute method.

MItGeometry (MDataHandle &dataHandle, unsigned int groupId, bool readOnly=true, MStatus *ReturnStatus=NULL)

Re: Multiple weight maps like skinCluster

jmreinhart — Mon, 10 Aug 2020 17:01:58 GMT

So I came back to this after a few months and tried creating an MItGeometry by using forceCache in the paintIndexChanged callback function. It just seems to cause a lot of problems, like crashing when I edit the deformer set even if the iterator isn't being used.

I found this ILM writeup on skinning and the Maya API helpful, and made some of the changes it suggests elsewhere in my code to help with performance, but it didn't solve the main problem:

http://www.spherevfx.com/downloads/Skinning%20in%20Maya%20at%20ILM.pdf

I feel like I'm at a dead end, I don't see how the skinCluster can do it so quickly. I really want to get this working because the deformer works fine it's just being able to paint on all the weight maps easily.