diff --git a/src/GEOMImpl/GEOMImpl_MeasureDriver.cxx b/src/GEOMImpl/GEOMImpl_MeasureDriver.cxx index 70a0fb545..c3b9cd0ca 100644 --- a/src/GEOMImpl/GEOMImpl_MeasureDriver.cxx +++ b/src/GEOMImpl/GEOMImpl_MeasureDriver.cxx @@ -216,6 +216,17 @@ Standard_Integer GEOMImpl_MeasureDriver::Execute(TFunction_Logbook& log) const gp_Vec Vec1,Vec2; BRepAdaptor_Surface SF (aFace); SF.D1(pUV.X(), pUV.Y(), p1, Vec1, Vec2); + if (Vec1.Magnitude() < Precision::Confusion()) { + gp_Vec tmpV; + gp_Pnt tmpP; + SF.D1(pUV.X(), pUV.Y()-0.1, tmpP, Vec1, tmpV); + } + else if (Vec2.Magnitude() < Precision::Confusion()) { + gp_Vec tmpV; + gp_Pnt tmpP; + SF.D1(pUV.X()-0.1, pUV.Y(), tmpP, tmpV, Vec2); + } + gp_Vec V = Vec1.Crossed(Vec2); Standard_Real mod = V.Magnitude(); if (mod < Precision::Confusion())