(I got a little cocky there. My script doesn't do a check for hard edges!) On Thursday, 5 April 2018 15:51:55 UTC+10, Michael Boon wrote: > > It's a bit of a myth, or at least an over-simplification, to say that > PyMel is slower and maya.cmds is faster. MEL and maya.cmds tend to be slow > because they do string processing for almost everything (and for that > reason they're also error-prone once you get into scenes with instances). > PyMel tends to be slow because it often wraps maya.cmds, and then spends > more time creating Python objects for things, but it can also be faster > than cmds because it often wraps the API and sometimes you can get the API > to do the work under the hood where cmds would be juggling strings. > > So in general, like Justin suggested, profile your code (there's a profile > module in Python) and look for hot spots. > > In this case though, I have written a script using PyMel that I can't > share, but it's only 8 simple lines and I think it does what you want, > plenty fast for your needs. Sorry! That's rude I know, but I don't own it! > Use the MeshFace class, and its methods connectedFaces and getNormal. Don't > use ls or polyListComponentConversion at all in your loop - those can be > pathological examples of PyMel slowness. > > I hope that helps :) > > > On Wednesday, 4 April 2018 14:44:28 UTC+10, Darby Edelen wrote: >> >> Hello, >> >> I'm new to the list and relatively new to Maya. >> >> I've been missing a tool in Cinema 4D that allows the user to select >> contiguous faces within boundaries defined by differences in polygon normal >> angles (boundaries = hard edges or an arbitrary angle), so I rolled my own >> Maya script. >> >> It seems to be working well, but it gets quite slow as the number of >> faces to select increases. For example, on my home PC it takes about 6 >> seconds to select 320 faces along the inside of a ring. >> >> If you have any ideas on how I could implement this more efficiently I >> would love your input. I've heard that PyMEL tends to be the slowest of >> options for scripting, but it's super convenient to work in a more >> 'pythonic' mode. I started playing with the OpenMaya API but found that it >> doesn't seem to have a polyListComponentConversion equivalent and my brain >> is fried enough that I can't think about implementing my own version using >> the API. I have a suspicion that the polyListComponentConversion function >> is one of those adding the most time to execution; I'm using it to find >> the boundary edges of the faces currently marked for selection. >> >> I've attached a .py file and pasted my code here as well: >> >> import pymel.core as pm >> import time >> import itertools >> >> def compare_normals(n1, n2): >> #Take dot product of normals and convert to degrees difference >> return 90.0 * (1.0 - n1*n2) >> >> def check_angle(edge, angle, hard_edges=True): >> if edge.isOnBoundary(): >> #Boundary reached; no need to continue! >> return False >> >> soft = True >> if hard_edges: >> #Check for hard or soft edge >> soft = edge.isSmooth() >> >> #Get all faces connected to this edge >> faces = pm.ls(edge.connectedFaces(), fl=True) >> #Compare the face normals between edges to determine if the face >> should be selected >> face_compare = {c for c in itertools.combinations(faces, 2) if >> compare_normals(c[0].getNormal(), c[1].getNormal()) > angle} >> >> #Returns True if the face should be selected >> return len(face_compare) == 0 and soft >> >> >> def get_connected_faces(faces, angle=0.0, hard_edges=True): >> #Get edge boundary of current face selection >> boundary = pm.ls(pm.polyListComponentConversion(faces, bo=True, >> te=True), fl=True) >> #Combine currently selected faces with neighboring faces that pass >> the face normal test >> new_faces = faces | set(pm.ls([edge.connectedFaces() for edge in >> boundary if \ >> check_angle(edge, angle, hard_edges)], >> fl=True)) >> >> if new_faces != faces: >> #Yield the new faces to select for as long as we haven't >> exhausted our supply >> yield new_faces >> #Stop when there are no more faces to select >> raise StopIteration >> >> t1 = time.clock() >> >> angle_tolerance = 30.0 >> hard_edges = True >> >> #Get the initial selection >> selection = pm.ls(sl=True, fl=True) >> #Filter the selection to face components >> selected_faces = {face for face in selection if isinstance(face, >> pm.general.MeshFace)} >> >> if selected_faces: >> #Since there are faces selected... >> try: >> while True: >> #Find new neighboring faces until no more meet the criteria >> selected_faces = get_connected_faces(selected_faces, >> angle_tolerance).next() >> except StopIteration: >> #Select all faces found >> pm.select(selected_faces) >> t2 = time.clock() >> #Report our performance >> print("Selected {0} faces in {1:.2f} >> seconds.".format(len(selected_faces), t2-t1)) >> >> >> >>
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