Edge Concavity or Convexity - Forum Open Cascade Technology

ataeft
Tue, 07/19/2011 - 00:37

Forums:

Hi,
Is there an easy way to know if an edge (of a solid) is Convex or Concave in Opencascade?
Is there any function for that?

jelle
Tue, 07/19/2011 - 01:04

just sample the gaussian curvature; the sign will tell you whether its [locally] convex or concave.

ataeft
Tue, 07/19/2011 - 01:12

Thanks, do you know the function for that?

jelle
Tue, 07/19/2011 - 02:15

see the LProps class...

ataeft
Tue, 07/19/2011 - 18:59

Thanks, I found that,

here is my code:

GeomLProp_CLProps aCurrentCurve_Props(aCurrentCurve, 1, gp::Resolution());
Standard_Real aCurrentCurve_Curvature = aCurrentCurve_Props.Curvature();

But the curvature is always 0!! do you know what is the problem here?

jelle
Tue, 07/19/2011 - 19:11

gauss curv. 0 means you're sampling either a developable surface, or in case of an edge, its a straight line.

Roman Lygin
Tue, 07/19/2011 - 19:21

... or forgot to call SetParameter() before calling Curvature() ;-)

ataeft
Tue, 07/19/2011 - 19:30

Ok, I was trying to capture concavity or convexity of an edge (lets say in a polyhedral).
So I think it is not possible to do that with this approach? if all the edges are line segments..

jelle
Tue, 07/19/2011 - 21:50

correct. however the topic is "Edge Concavity or Convexity", so this is a completely different question ;)
though TopoDS_Shape offers a "Convex" method

ataeft
Wed, 07/20/2011 - 00:02

I used Convex method, but it is not working..
I always shows a constant number!

ataeft
Wed, 07/20/2011 - 00:03

Convex method in "TopoDS_Edge"