How to create TopoDS_Edge from to gp_Pnt in OpenCASCADE

OCCUtils provides a conveniece function for creating a TopoDS_Edge between two points (i.e. a straight line):

edge_from_points_occ.cpp
#include <occutils/Edge.hxx>

using namespace OCCUtils;

gp_Pnt p1 = /* ... */;
gp_Pnt p2 = /* ... */;

TopoDS_Edge edge = Edge::FromPoints(p1, p2);

In case you want to do it manually (i.e. without OCCUtils), use this snippet

makeedge_manual.cpp
TopoDS_Edge edge = BRepBuilderAPI_MakeEdge(p1, p2).Edge();

but be aware that you also have to handle the case of p1 == p2 i.e.

check_points_equal.cpp
if (p1.Distance(p2) <= Precision::Confusion()) {
    // Don't try to create an Edge in this case
}

OCCUtil’s Edge::FromPoints handles this case by returning TopoDS_Edge() i.e. a TopoDS_Edge where edge.IsNull() == true.


Check out similar posts by category: C/C++, OpenCASCADE