Splitting a curve in 2

[BenoitE&A]

Hi,

My problem is only 2D.

I am trying to do the following : 

- let's say I have 2 curves. I compute their intersection using curve1.Intersect(curve2, out IntersectionResultArray ira);

- Then I want to split each curve into 2 curves, one on each side of the intersection.

Here is the code :

Curve curve1, curve2, curve11, curve12, curve21, curve22;

curve1.Intersect(curve2, out IntersectionResultArray ira);

if(ira!=null) 

{

IntersectionResult ir = ira.get_item(0);

double param = ir.Parameter;

curve11 = curve1;

curve11.MakeBound(curve11.GetEndPointParameter(0),param);

etc...

}

The thing is : the code line 

double param = ir.Parameter;

systematically returns an error message (InvalidOperationException) whatever the curves are. 

I tryed on simple curves (lines) as well as arcs and the error message always occurs.

Any idea where this comes from? Or another simple way to deal with this?

Benoit

[JimJia · Accepted solution]

Dear Benoit,

IntersectionResult.Parameter is invalid when 2 curves intersects, you need to use IntersectionResult.XYZPoint.

Please see codes below:

IntersectionResultArray ira = null;
XYZ intersectionPoint = null;

if(curve1.Intersect(curve2, out ira) == SetComparisonResult.Overlap)
{
intersectionPoint = ira.get_Item(0).XYZPoint;
}

double paraIntersection1 = curve1.Project(intersectionPoint).Parameter;
double paraIntersection2 = curve2.Project(intersectionPoint).Parameter;

Curve c11 = curve1.Clone();
c11.MakeBound(curve1.GetEndParameter(0), paraIntersection1);
Curve c12 = curve1.Clone();
c12.MakeBound(paraIntersection1, curve1.GetEndParameter(1));

Curve c21 = curve2.Clone();
c21.MakeBound(curve2.GetEndParameter(0), paraIntersection2);
Curve c22 = curve2.Clone();
c22.MakeBound(paraIntersection2, curve2.GetEndParameter(1));

[BenoitE&A]

Hi Jim,

Indeed that 's what I had thought in my shower this morning : if IntersectionResult.Parameter is not valid for curve intersection then I have the projection tool to get the parameters of the intersection for each curve.

Thanks for the reply.

I have a quick question : if instead of using

Curve c11 = curve1.Clone(); 

I code 

Curve c11 = curve1;

Then do the same, will it work or not?

Benoit