(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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