Sun, 02/20/2005 - 16:19
Forums:
Hi,
I have a Handle(Geom_BSplineCurve) c, c->IsClosed()==true. Now, I do c->SetPeriodic(), OK. Then, however, I reparametrize the curve by saying c->Segment(u1,u1+c->Period()), where 0
Looking into Geom_TrimmedCurve.cxx, this exception is raised only for non-periodic basisCurve=Handle(Curve)::DownCast(C->Copy()) in the constructor. Am I right thinking that Geom_Curve::Copy does not preserve periodicity? How can I use segments crossing period boundary?
Thanks for any hints. Regards, VS
Tue, 02/22/2005 - 23:08
Hi Vaclav,
I guess the point is not in Copy(), which just clones the curve but in ->SetPeriodic() which did not produce a periodic curve. Not any closed BSpline can be made periodic – for instance if its boundary knots has multiplicity = degree + 1, this certainly won’t work (since continuity condition is violated). Check SetPeriodic() by inspecting source code and you can always check its result by querying IsPeriodic().
HTH.
Roman
Fri, 02/25/2005 - 18:14
Roman, thanks for your reply, documentation indeed metions that knots table needs to be periodic. In that contrary case, however, I think SetPeriodic _should_ throw, just like it does for non-closed curves. I found that ShapeConstruct_Curve::ConvertToPeriodic might take care of all that business seamlessly (have not tried it yet).
Tue, 03/01/2005 - 21:48
ShapeConstruct_Curve::ConvertToPeriodic works fine. I make a period-long segment that starts at e.g. u=0.43, then such curve has parametrization [0.43;1.43]. Now the problem is that GeomAdaptor_Curve does not apparently know anything about LastParameter()>1 and UniformDeflection does not return any point beyond u=1, even if parameter range passed to the constructor is correct. Any ideas?
Regards, Vaclav