Edge direction vs Curve direction

Do the start vertex of an edge and first parameter of the curve of this edge always correspond same point? i.e. have edge and curve same direction? If not, how can i know whether their directions are same or not?


Cauchy Ding's picture

Hi xaeroxx,

Curve has no similar direction concept with edge in topology. To make sure the start vertex of edge and first parameter of curve share the same point, set the last parameter of TopExp::FirstVertex as false, the declaration is:
//!CumOri = True : taking account the edge orientation
Standard_EXPORT static TopoDS_Vertex FirstVertex(const TopoDS_Edge& E,const Standard_Boolean CumOri = Standard_False);
Good luck.

Francois Lauzon's picture

Hello xaeroxx,
the orientation (direction) may not be the same, if it's the same, the TopoDS_Shape::Orientation() will be TopAbs_FORWARD, if it's reversed, Orientation() will be TopAbs_REVERSED.

Good Luck,

Divya's picture

while trying to order the edges
the result of status() in ShapeAnalysis_WireOrder is :
-1 : some edges are reversed, but no gap remain

what does this mean?