create face from curves/wires 

Marco 
2013/01/26 14:13 
Hi,
I have the following situation. I load some points which describes closed curves. I give the points to the PointsToBSpline algorithm to get the curve.
TColgp_Array1OfPnt arr(0,points.size()1);
for(unsigned int i = 0;i < points.size();++i)
{
arr.SetValue(i,gp_Pnt(points[i].X(),points[i].Y(),points[i].Z()));
}
auto spline = GeomAPI_PointsToBSpline(arr,3,8,GeomAbs_C2,0.00001);
spline.Curve()>SetPeriodic();
return spline;
Here I have a first question. Is it necessary that the last point is identical to the first point so that opencascade really makes a closed curve?
Then I create egdes and wires from the b spline curves. That works fine.
And now the more import question for me. I want co create a face (and later a solid) from these curves, the first step is to create a face which are limited by two of such closed curves. The MakeFace algorithm doesn't work because it works with planar edges.
SO, how can create a face from two given closed b spline curves?
Best regards
Marco 
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 Marco 
2013/01/28 13:35 
Any suggestions? 

 
 Mauro Mariotti 
2013/01/28 18:27 
1. For sure to have a closed spline, the last point must be coincident with the first.
2. Maybe you can use BRepFill_Filling with the outer wire to create a face and then split it with the inner one, using BRepFeat_SplitShape.
Ciao.
Mauro 

 
 Marco 
2013/01/28 20:51 
I tested a little bit with BRepFill_Filling, but it crashes.
Is there really no algorithm to get a surface from two curves? I read the pdf's from the documentation folder and also found nothing :(
Any other suggestions? 

 
 Marco 
2013/01/28 22:34 
So, I tested it with GeomFill_BSplineCurves, that alorithm works better (see attached image)
As you can see there are some errors at the connecting line.
One problem is still left: the algorithm only works if the flag SetPeriodic isn't set.
If I use "spline.Curve()>SetPeriodic();" than the allgorithm crashes during runtime! Therefore, my resulting faces are not really periodic. It looks only so.
That is the code for the spline creation:
TColgp_Array1OfPnt arr(0,points.size()1);
for(unsigned int i = 0;i < points.size();++i)
{
arr.SetValue(i,gp_Pnt(points[i].X(),points[i].Y(),points[i].Z()));
}
auto spline = GeomAPI_PointsToBSpline(arr,2,7,GeomAbs_C1,0.00001);
First and last point in the array are identical! Did I something wrong? 
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 Marco 
2013/02/05 17:20 
*push*
still unsolved 

 
 Alexander Luger 
2013/07/09 17:03 
I always used GeomAPI_Interpolate for my splines. The constructor of this class takes a periodic flag! 

 
 Timo 
2013/07/12 13:43 
For creating a face from 2 curves you can also use
BRepFill.Face(const TopoDS_Edge &Edge1, const TopoDS_Edge &Edge2)
You might also have a look at BRepOffsetAPI_ThruSections. 

   