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offset curve direction

Other usage issuesWed, 07/10/2013 - 21:461 reply

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QuestionAuthor

I can't believe it.

The documentation of Geom_OffsetCurve says:
"The Offset curve is in the direction of the normal N defined with the cross product V^T
where the vector T is given by the first derivative on the basis curve with non zero length"
(V is the reference direction).

In the code the cross product is reversed:

void Geom_OffsetCurve::D0(const Standard_Real U,
gp_Pnt& P,
gp_Pnt& Pbasis,
gp_Vec& V1basis)const
{
basisCurve->D1 (U, Pbasis, V1basis);
// ...
XYZ Ndir = (V1basis.XYZ()).Crossed (direction.XYZ()); // this is T^V !

So for a planar curve (with V = (0,0,1)) the offset is positive on the right and negative on the left, contrary to what the documentation says.

Can anyone confirm this?
Thanks.
Author

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1 archived reply

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01Commenter-1

Hello Author,
Thank you very much for the revealed mistake. It is fixed in the issue 0024062 (http://tracker.dev.opencascade.org/view.php?id=24062).