GetEdgeCount() Bug?

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On 05/02/2012 at 11:49, xxxxxxxx wrote:

User Information:
Cinema 4D Version:   12 
Platform:   Windows  ;   
Language(s) :

---------
I'm not getting the correct results from GetEdgeCount(). It's not returning the correct amount of edges in an object. It always comes up short.
I'm testing this in Python. But since Python is just wrapping around the C++ API. It might be coming from C++.

Here's an example:

import c4d  
from c4d import utils  
  
def main() :  
  obj = doc.GetActiveObject()      #A cube object  
  nibr = utils.Neighbor()          #Assigns neighbor to a variable  
  nibr.Init(obj)                   #Instantiates the neighbor class using the "obj"  
  edgecount = nibr.GetEdgeCount()  #Get all the edges in the entire polygon object  
  print edgecount    #Prints 12!? <----This should be 16!!!                  
  
  edges = c4d.BaseSelect() #Create a BaseSelect object  
  
  mylist = [x for x in range(edgecount)] #Creates an array size based on GetEdgeCount()   
  print mylist  
  edges.SetAll(mylist)  
  
  edges.CopyTo(obj.GetEdgeS())  #Makes the edges selected in the scene from memory  
                                #Only 12 edges are selected because GetEdgeCount() failed!?  
  
  c4d.EventAdd()  
  
if __name__=='__main__':  
  main()

When I use this on a more complex object. The number of missed edges climbs.
Is this a bug?

Update:
I got a chance to try this is in C++ and got the same wrong edge count results:

    BaseDocument *doc = GetActiveDocument();  
  BaseObject *op = doc->GetActiveObject();  //A cube object  
  if (!op) return FALSE;  
  
  if (op->GetType() == Opolygon)  
  {  
   Neighbor n;  
   if (!n.Init(ToPoly(op)->GetPointCount(),ToPoly(op)->GetPolygonR(),ToPoly(op)->GetPolygonCount(),NULL)) return FALSE;  
  
   LONG ecount = n.GetEdgeCount();    // Count the edges in the object  
   GePrint(LongToString(ecount));     //<---Prints 12!?.......Should be 16!!!

Could someone from Maxon please confirm this as either bug, or user error.
I can't use it until I know what's really going on with it.

-ScottA

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On 05/02/2012 at 14:59, xxxxxxxx wrote:

This is very confusing.

-There are 24 edges in a cube. If you count each polygon as a separate face
-GetEdgeCount() returns 12 edges. So using that I end up with all but three edges selected
-If I use an array with 16 elements in it as the source for SetAll(myarray). Every edge of the cube is selected as expected.

All I want to do is use GetEdgeCount() to get the number of edges in an object. Like the name of the function implies. Then use that number to select them later on.
But it looks like I can't do that because GetEdgeCount() does not count every single edge as the name implies.

What it looks like I'm having trouble with. Is figuring out how these various functions determine what an edge is. And when they are/and are not, counting them.

-If I use edgecount = nibr.GetEdgeCount()*2 it does select all the edges of a cube.
-If I use edgecount = nibr.GetEdgeCount()*2 on a plane. It selects all but one edge.
-If I use edgecount = nibr.GetEdgeCount()*2 on a  sphere. I get five unselected  edges at the poles.

Is this the desired result for GetEdgeCount() ?
The more I try to use it. The more confused I get. 😵

-ScottA

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On 06/02/2012 at 09:33, xxxxxxxx wrote:

If you look at PolygonObject.GetSelectedEdges() documentation, it's stated that: "The edges are indexed uniquely by a Neighbor object, so each edge has a single index."
So there are only 12 edges in a cube. We can see that looking at the information returned by Neighbor.GetPolygonCount() :

for i in xrange(op.GetPolygonCount()) :
    pli = nbr.GetPolyInfo(i)
    print pli

There's some missing documentation for the information returned by Neighbor.GetPolygonCount() for the Python docs. You can take a look at the C++ docs for this method.
'mark' indicates if an edge is new or was already built. There are 12 False 'mark' and 12 True 'mark'.

BaseSelect.SetAll() accepts an array of selection states , 0 or 1 values, not indices. So you should build the edges selection array like this:

mylist = [1 for x in range(edgecount)]

And to select edges it works as expected calling PolygonObject.SetSelectedEdges().

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On 06/02/2012 at 10:51, xxxxxxxx wrote:

Originally posted by xxxxxxxx

And to select edges it works as expected calling PolygonObject.SetSelectedEdges().

Thanks for the help Yannick.
But I still can't select all edges of a polygon object using that information.
Example:

import c4d  
from c4d import gui,utils  
  
def main() :  
  
  obj = doc.GetActiveObject()       #A cube object  
  nbr = utils.Neighbor()            #Assigns neighbor to a variable  
  nbr.Init(obj)                     #Instantiates the neighbor class using the "obj"  
  edgecount = nbr.GetEdgeCount()    #Get all the edges in the entire polygon object  
  
  for i in xrange(op.GetPolygonCount()) :  
      pli = nbr.GetPolyInfo(i)  
      print pli  
  
  mylist = [1 for x in range(edgecount)] #Set all edges to True  
  
  obj.SetSelectedEdges(nbr,mylist,c4d.EDGESELECTIONTYPE_SELECTION)#<--Error:c4d.PolygonObject has no attribute 'SetSelectedEdges'  
  
if __name__=='__main__':  
  main()

Any chance of seeing a proper working example of this?

Thanks,
-ScottA

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On 06/02/2012 at 11:18, xxxxxxxx wrote:

Ah... you may be using a pre-R13 version. SetSelectedEdges() was added to the Python SDK in version R13.

Here's how to do without SetSelectedEdges() :

import c4d
from c4d import utils
  
def main() :
    nbr = utils.Neighbor()
    nbr.Init(op)
    indices = [1 for i in range(nbr.GetEdgeCount()*2)]
    edges = c4d.BaseSelect()
    edges.SetAll(indices)
  
    edges.CopyTo(op.GetEdgeS())
    c4d.EventAdd()
  
if __name__=='__main__':
    main()

SetSelectedEdges() works with unique edges but GetEdgeS() not. I just reversed engineered GetEdgeS() getting the current selection and it's 24 edges when we select all the edges. In R13 with GetSelectedEdges() it's 12 edges. So it's more or less what you tried before 🙂 except the edges array is built with selection states values.

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On 06/02/2012 at 12:11, xxxxxxxx wrote:

Lol.
Isn't it fun trying to troubleshoot these functions when they get updated so often from version to version?😉
That code you posted brings me back to my original problem.
*2 works for a cube. But it does not select all edges on a sphere for example.
I've even tried multiplying nbr.GetEdgeCount() * 3.02 and that still doesn't work in all cases.
But lets forget about R12 at this point. And call it not supported. And just focus on R13 from now on...OK?
No sense trying to get the older version to work at this point.

Can you please post a code example that selects all edges in an object for R13 using the "op.SetSelectedEdges" function?
But before you post it. Please try it out on both a cube and a sphere.
I'm still getting the same results in R13 as r12. And I want to see if you get the same results.

Thanks,
-ScottA

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On 06/02/2012 at 12:27, xxxxxxxx wrote:

Originally posted by xxxxxxxx

Can you please post a code example that selects all edges in an object for R13 using the "op.SetSelectedEdges" function?
But before you post it. Please try it out on both a cube and a sphere.
I'm still getting the same results in R13 as r12. And I want to see if you get the same results.

Here's the working code for any polygon object in R13 using SetSelectedEdges() :

import c4d
from c4d import utils
  
def main() :
    nbr = utils.Neighbor()
    nbr.Init(op)           # Initialize neighbor with a polygon object
    
    selection = [1 for i in range(nbr.GetEdgeCount())] # Select all the edges = set them to 1
    edges = c4d.BaseSelect()
    edges.SetAll(selection)                            # Set the edges selection with the selection list
  
    op.SetSelectedEdges(nbr, edges, c4d.EDGESELECTIONTYPE_SELECTION) # Select edges from our edges selection
    c4d.EventAdd() # Update CINEMA
  
if __name__=='__main__':
    main()

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On 06/02/2012 at 12:34, xxxxxxxx wrote:

Excellent.
I think I've got it all sorted out now.

Thanks a lot for sticking with me on this one.🍺

-ScottA

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On 06/02/2012 at 12:53, xxxxxxxx wrote:

If you want to select all edges you should be able to use

  
edges.SelectAll(edgecount)   
obj.SetSelectedEdges(nibr,edges,c4d.EDGESELECTIONTYPE_SELECTION)   

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On 06/02/2012 at 13:16, xxxxxxxx wrote:

Yeah. That's true Lennart.

I'm using arrays in my examples because it gives me a way to iterate through my selections.
AFAIK. BaseSelection is not iterable. That's why I'm using arrays(lists) in my code.

Probably a good idea that you pointed that out for the sake of others new to this subject that don't need or want that extra iteration ability.

-ScottA

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On 06/02/2012 at 15:17, xxxxxxxx wrote:

You could iterate using enumerate and get a list:

  
# Get Set Edges Test R13   
import c4d   
from c4d import utils as u   
  
def main() :   
    obj = doc.GetActiveObject()   
    if obj is None or not obj.CheckType(c4d.Opolygon) :   
        return True   
    n   = u.Neighbor()   
    n.Init(obj)   
    edgecount = n.GetEdgeCount()   
    print edgecount   
    edges = obj.GetSelectedEdges(n, c4d.EDGESELECTIONTYPE_SELECTION)   
    elist = []   
    for i, sel in enumerate(edges.GetAll(edgecount)) :   
        if sel: elist.append(1)   
        else:   elist.append(0)   
    print elist   
    edges.SetAll(elist)   
    obj.SetSelectedEdges(n, edges, c4d.EDGESELECTIONTYPE_SELECTION)   
    c4d.EventAdd()   
  
if __name__=='__main__':   
    main()   

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On 06/02/2012 at 17:59, xxxxxxxx wrote:

Yeah I know. That's what I've been doing in R12.
Although lately I've been using a different method where I iterate from inside of the the lists themselves.
Same difference.😉

I got hung up on trying to select all edges. GetEdgeCount() didn't work as I expected it to work.
I'm good to go now. Except that now I'm forced to use R13. 😠

I'm still thinking that this should be possible to do in R12 though.
Since we can iterate selections using lists. I would think that we should be able to step through the polygons and get & set every edge that way. But I couldn't make it work.
It might  require getting each polygon point(A,B,C,D).
Then using that to find all the edges. And putting that into a list.
Then using that list to select the edges.

That's kind of advanced stuff for me right now. I'm still not very good with polygons & edges.

-ScottA

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On 07/02/2012 at 01:28, xxxxxxxx wrote:

Originally posted by xxxxxxxx

I got hung up on trying to select all edges. GetEdgeCount() didn't work as I expected it to work.
I'm good to go now. Except that now I'm forced to use R13. 
I'm still thinking that this should be possible to do in R12 though.

Here's the code for R12:

import c4d
from c4d import utils
  
def main() :  
    numEdges = op.GetPolygonCount()*4
    
    edges = c4d.BaseSelect()
    edges.SelectAll(numEdges-1)
  
    edges.CopyTo(op.GetEdgeS())
    c4d.EventAdd()
  
  
if __name__=='__main__':
    main()

As you can see, the number of edges is the number of polygons multiplied by 4 (4 edges per polygon). GetEdgeS() doesn't work with shared edges, Neighbor and the methods using it (GetSelectedEdges(), SetSelectedEdges()) do.
I select all the edges to numEdges-1 and not to numEdges because I found an issue with SelectAll(). The number of selected elements is number+1 the number you pass to the method.

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On 07/02/2012 at 08:01, xxxxxxxx wrote:

Thanks for that Yannick.
But I should have mentioned that I needed to be able to select all edges using a list. I'll see if I can use this in my project using lists.

This is all based on a bigger project I'm working on. Where I'm trying to select just one side of the outer edges of "shells" (also known as "islands" ) inside of a polygon. And convert them to splines.
Maya has tools and functions for working with polygon and UV shells and I'm trying to build my own in C4D.
Currently the only way I can do this is to use the ExplodeSegments command. Then select the desired edges on each generated polygon object.
This works ok. (I posted the script on CGTalk) But the problem is I have to generate thousands of objects this way(Ouch!). Just to generate those splines. And that's both very slow and very resource hungry. And frankly a bit of a hack.

So now I'm trying to use lists to try and cut these shells inside the polygon into groups so I can work with them as if they were individual objects. Sort of like using lists in place of a selection tags.
I need to be able to select all edges...But not just simply all edges. All edges per each shell... And not just all edges..But only the edges on one side of all these shells.
It's a rather complex problem.

I posted about it in another thread in the C++ forum.
The source code in the ExplodeSegments command might help me learn how to split up a polygon into groups. I don't even know if my approach is a good one.

This is what I've come up with so far.
It's almost there(it currently only selects the first shell's edges). But then I ran into selection problems:

import c4d  
from c4d import utils  
  
def main() :  
  
################## Put polygon shells into an array #####################################  
  c4d.CallCommand(12187)  #Polygons Mode  
  c4d.CallCommand(13324)  #Deselect All polygons--Start from no polygons selected  
  lastsel = 0  
  
  obj = doc.GetActiveObject()     
  polycount = obj.GetPolygonCount()  
  selected = obj.GetPolygonS()       #The selected polygons  
  selected.Select(0)                 #Select the first polygon  
  c4d.CallCommand(12557)             #Select Connected polygons  
  selectedcount = selected.GetCount()#How many polygons per shell  
  polygons = c4d.BaseSelect()  
  polysPerShell = 0                  #The number of polygons per shell  
  
  polygonlist = []    #The list of shell arrays(contains the individual lists for each shell)   
  
  for i in xrange(polycount/selectedcount) :  
      #print "shells:" ,i  
      newpolygonlist = []              #This list will be used to hold the selected polygons  
      for i in xrange(polycount) :      #Loop amount = total number of polygons  
          if selected.IsSelected(i) :   #Look for selected polygons  
               polysPerShell = polysPerShell +1  #The number of polygons per shell                 
               newpolygonlist.append(i)#Fill the list with the selected polygons  
               lastsel = i             #This is the last selected polygon's Id#  
        
      polygonlist.append(newpolygonlist)  
      c4d.StatusSetSpin()              #Show the spinning staus bar  
      c4d.CallCommand(13324)           #Deselect All polygons  
      selected.Select(lastsel+1)       #Select the first polygon in the next shell   
      c4d.CallCommand(12557)           #Select Connected polygons  
################### Done with loop #################################################  
     
  pnts = obj.GetAllPoints()  
  edges = c4d.BaseSelect()  
  pntcount = obj.GetPointCount()  
  nibr = utils.Neighbor()          #Assigns neighbor to a variable  
  nibr.Init(obj)                   #Instantiates the neighbor class  
  edgecount = nibr.GetEdgeCount()  #Get all the edges in the entire polygon object  
  #print "total edges:", + edgecount     
  #print polysPerShell               
   
  shellpolylist = []  
  
  for i in xrange(len(polygonlist)) : #This gives the number of shells  
      shells = i                         
      #print shells  
      for shells in polygonlist:     #For each shell of polygons in the "polygonlist" array  
          #print shells  
           for j in xrange(0,polysPerShell) : #For each shell element  
               #print j                  
               selected.Select(j)            #Select each element(polygon)                   
               shellpolylist.append(j)       #Add each polygon to the list  
  
      edges.Select(shellpolylist[1])  
      edges.Select(shellpolylist[5])  
      edges.Select(shellpolylist[9])  
  #print shellpolylist  
  edges.CopyTo(obj.GetEdgeS())  
  
  #Convert selected objects to splines  
  utils.SendModelingCommand(c4d.MCOMMAND_EDGE_TO_SPLINE, list = [obj], mode = c4d.MODIFY_ALL, bc = c4d.BaseContainer(), doc = doc)  
  
  c4d.CallCommand(16351)            #Edges    
  c4d.StatusClear()                 #Remove the spinning bar..We're done  
  #print edgelist  
  c4d.EventAdd()      
  
if __name__=='__main__':  
  main()

I'm not sure if I'm on the right track or not.
I'm in a little bit over my head. And just looking for advice on doing this.
Not really a support issue. Just wanted to let you see what I was trying to do in the bigger picture.

-ScottA