Thu, 08/17/2000 - 12:11
Forums:
Hi All,
I have a small problem !. I create an arc using,
Handle(Geom_TrimmedCurve) curve = GC_MakeArcOfCircle(...)
however, when I examine the type of this curve later on using downcasting.....
Handle(Geom_TrimmedCurve)::DownCast(curve).IsNull()
returns true but.....
Handle(Geom_Circle)::DownCast(curve).IsNull()
return false.
Is this the correct behaviour for the down cast to return the basis curve type or am I doing something stupid. ?
Thanks in advance.
Simon
Mon, 08/21/2000 - 10:03
Hello, Simon!
Your results seem to be strange. In this case DownCast() method must return not null curve only for Geom_TrimmedCurve type.
You can not downcast Geom_TrimmedCurve to Geom_Circle. Because these classes have no inheritable links.
To obtain basis curve of an arc (Geom_Circle in this case) you can use BasisCurve() method. For example:
Handle(Geom_TrimmedCurve) aTrimmedCurve = GC_MakeArcOfCircle(...);
Handle(Geom_Curve) aCurve = aTrimmedCurve->BasisCurve();
Handle(Geom_Circle) aCircle = Handle(Geom_Circle)::DownCast(aCurve);
The circle obtained by this way is not null.
Best regards, Sergey.
Wed, 12/23/2015 - 13:15
I've faced the same problem as Simon mentioned above.
First, I create Geom_TrimmedCurve with Geom_Circle, startAngle and endAngle.
Got True when downcast using Geom_TrimmedCurve.DownCast(curve).INull
Got False when downcast using Geom_Circle.DownCast(curve).IsNull, means it is a circle.
When I draw this curve on the canvas, I got a circle even I've made it as arc.
Dose anyone has some idea about this?
Thanks a lot
Joba