如何封闭SPLINE？

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How to close an AcDbSpline?

By Augusto Goncalves

There is no specific isClosed() method defined for AcDbSpline as there is for
AcDbPolyline. However, in many cases, an AcDbSpline can be closed. Here is a
simple solution to implement a setClosed function for splines. It uses the
getNurbsData() and setNurbsData() AcDbSpline methods. getNurbsData will gather
the information about the spline, including a Boolean closed that indicates if
the spline is closed or not. setNurbsData() takes the same arguments as
getNurbsData(), so only the closed argument will be changed to Adesk::kTrue to
obtain the desired result.

And the same idea can be applied to the .NET Spline.NurbData property.

1. 
   
2. void setClosed(AcDbSpline *pSpline)
   
3. {
   
4.     int          degree;
   
5.     Adesk::Boolean    rational;
   
6.     Adesk::Boolean    closed;
   
7.     Adesk::Boolean    periodic;
   
8.     AcGePoint3dArray  controlPoints;
   
9.     AcGeDoubleArray    knots;
   
10.     AcGeDoubleArray    weights;
    
11.     double        controlPtTol;
    
12.     double        knotTol;
    
13. 
    
14.   // get data from the spline
    
15.     pSpline->getNurbsData(degree, rational, closed, periodic,
    
16.                  controlPoints, knots, weights,
    
17.                  controlPtTol, knotTol);
    
18. 
    
19.   if(closed == Adesk::kTrue)
    
20.         return;
    
21. 
    
22.   // set as closed
    
23.   closed = Adesk::kTrue;
    
24. 
    
25.   // apply data back
    
26.     pSpline->setNurbsData(degree, rational, closed, periodic,
    
27.                  controlPoints, knots, weights,
    
28.                  controlPtTol, knotTol);
    
29. }
    

<br /> void setClosed(AcDbSpline *pSpline)<br /> {<br />     int          degree;<br />     Adesk::Boolean    rational;<br />     Adesk::Boolean    closed;<br />     Adesk::Boolean    periodic;<br />     AcGePoint3dArray  controlPoints;<br />     AcGeDoubleArray    knots;<br />     AcGeDoubleArray    weights;<br />     double        controlPtTol;<br />     double        knotTol;<br /> <br />   // get data from the spline<br />     pSpline->getNurbsData(degree, rational, closed, periodic,<br />                  controlPoints, knots, weights,<br />                  controlPtTol, knotTol);<br /> <br />   if(closed == Adesk::kTrue)<br />         return;<br /> <br />   // set as closed<br />   closed = Adesk::kTrue;<br /> <br />   // apply data back<br />     pSpline->setNurbsData(degree, rational, closed, periodic,<br />                  controlPoints, knots, weights,<br />                  controlPtTol, knotTol);<br /> }<br />