I have been working through this post and another by Remi, trying to figure out how to get blendShape target offsets in the OpenMaya API. It's not easy! However I have figured out the answer to your question Enrico.
Your OM.MFnComponentListData(inputComponentsTarget_data) stores all the components in groups of successive component IDs. For example, if the components were [0, 1, 2, 3, 22, 23, 100, 101], it would have length 3. OM.MFnComponentListData(inputComponentsTarget_data)[0] would contain [0,1,2,3] OM.MFnComponentListData(inputComponentsTarget_data)[1] would contain [22,23] and OM.MFnComponentListData(inputComponentsTarget_data)[2] would contain [100,101] If you concatenate the contents of all those lists, you get the same number of components as you have points. On Sunday, 28 October 2018 08:45:27 UTC+11, Enrico Losavio wrote: > > (two and a half years later) > > I was wondering the same! 😅 > > I haven't touched this code in a long time. When I finally got it to work > I decided not to change, as there are a couple of things that I still don't > fully understand and I don't wanna break it. > This is the typical case of "It works!... But why?!" > > Today I was just looking back into it, cause I was investigating a small > issue (which is actually specific to one file only, so maybe just a quirk > of maya) where inputComponentsTarget and inputPointsTarget have different > lengths, but the blendShape node still works fine... For most of the poses, > the index list > > I was very surprised, cause a delta can't really be applied without > knowing which vertex to affect. Maybe the indices are stored somewhere > else? Maybe they're cached? > > > Now... I have also written some code to actually *write* my custom deltas > in the blendShape node. Here is an excerpt. > > index_list = OM.MIntArray() # indices to be written > deltas_list = OM.MPointArray() # deltas to be written (maya wants points > instead of vectors) ¯\_(ツ)_/¯ > > > #################################################################################### > ### values for index_list and deltas_list are assigned outside this code > snippet ### > > #################################################################################### > > # initializes function sets, needed to create the MObjects and set their > data > dg_component_fn = OM.MFnComponentListData() > dg_component_data = dg_component_fn.create() > singleComponent_fn = OM.MFnSingleIndexedComponent() > singleComponent_data = singleComponent_fn.create(OM.MFn.kMeshVertComponent) > singleComponent_fn.addElements(index_list) > > # write the index data in the inputComponentsTarget plug > if not singleComponent_data.isNull(): > dg_component_fn.add(singleComponent_data) > inputComponentsTarget_plug.setMObject(dg_component_data) > > print dg_component_fn.length() # <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< > this line prints 1 (in my test index_list and deltas_list had 11476 > elements each) > > # writes the delta data in the inputPointsTarget plug > dg_pointArray_fn = OM.MFnPointArrayData() > dg_pointArray_data = dg_pointArray_fn.create(deltas_list) > if not dg_pointArray_data.isNull(): > inputPointsTarget_plug.setMObject(dg_pointArray_data) > > print dg_pointArray_fn.length() # <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< > this line prints 11476 (correct!) > > > > It has always worked fine in the last few years, and it still works > correctly also with this file. > However, even after re-writing the blendShape targets in the node, the > indices still don't have the right length. > *With very few exceptions*,the length of the indices in > inputComponentsTarget is a very small value, between 1 and 5. > > > Here is an excerpt of the code to read the deltas from the blendShape > node. > > inputPointsTarget_data = inputPointsTarget_plug.asMDataHandle().data() > inputComponentsTarget_data = > inputComponentsTarget_plug.asMDataHandle().data() > > # to read the deltas, use a MFnPointArrayData > targetPoints = OM.MPointArray() > fnPoints = OM.MFnPointArrayData(inputPointsTarget_data) > fnPoints.copyTo(targetPoints) > > # use MFnSingleIndexedComponent to extract an MIntArray with the indices > dg_component_fn = OM.MFnComponentListData(inputComponentsTarget_data)[0] > # <<<<<<<<<<<< why does this need to be only the first element? > if dg_component_fn.isNull(): > continue > singleComponent_fn = OM.MFnSingleIndexedComponent(dg_component_fn) > targetIndices = OM.MIntArray() > singleComponent_fn.getElements(targetIndices) > > print "indices: ", targetIndices.length(), "points: ", > targetPoints.length() # <<<<<<<<<<<< prints "indices: 1 points: 11476" > > > > To be honest I am still a bit confused by some bits of this code. I *think > *I understand the combined use of MFnComponentListData and > MFnSingleIndexedComponent, but I'm not so familiar with these classes and > the documentation is pretty scarce. Also google wasn't very helpful, as > brought me back to this very thread that I started long time ago... > > Since I noticed this issue on one file only, I don't know if you'll be > able to replicate the same scenario. > However, maybe you can notice any anomaly in the way I'm handling this > data to put it in / take it out the plug. > > Can anyone shed some light on what's going on here? > Any help would be greatly appreciated! > > Thanks, > Enrico > -- You received this message because you are subscribed to the Google Groups "Python Programming for Autodesk Maya" group. To unsubscribe from this group and stop receiving emails from it, send an email to python_inside_maya+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/python_inside_maya/b9ec51c3-d7aa-434b-849e-c857546aa107%40googlegroups.com.
