/// <summary>
/// Searches for the longest edge of a shape, and find the longest parallel edge
/// </summary>
public static (TopoDS_Edge edge, Ax1?axis, TopoDS_Edge opEdge, Ax1?opAxis) FindLongestEdge(TopoDS_Shape shape)
{
TopoDS_Edge foundEdge = null;
Ax1? foundAxis = null;
TopoDS_Edge opEdge = null;
Ax1? opAxis = null;
// Find the longest edge to revolve around
double edgeLen = -1;
var edgeInfos = new List <(TopoDS_Edge edge, double len, Ax1 axis)>();
var edges = shape.Edges();
foreach (var edge in edges)
{
var brepAdaptor = new BRepAdaptor_Curve(edge);
if (brepAdaptor.GetGeomType() != GeomAbs_CurveType.GeomAbs_Line)
{
break;
}
var v1 = brepAdaptor.Value(brepAdaptor.FirstParameter());
var v2 = brepAdaptor.Value(brepAdaptor.LastParameter());
var len = v1.Distance(v2);
var axis = new Ax1(v1, new Vec(v1, v2).ToDir());
if (edge.Orientation() == TopAbs_Orientation.TopAbs_REVERSED)
{
axis.Reverse();
}
edgeInfos.Add((edge, len, axis));
if (foundEdge != null && foundEdge.IsSame(edge))
{
// Same edge with another orientation
if (foundEdge.Orientation() == TopAbs_Orientation.TopAbs_REVERSED &&
edge.Orientation() == TopAbs_Orientation.TopAbs_FORWARD)
{
// Prefer forward edges
foundEdge = edge;
}
continue;
}
if (len > edgeLen)
{
foundEdge = edge;
edgeLen = len;
foundAxis = axis;
}
}
if (foundAxis != null)
{
// Find opposite edge
edgeLen = -1;
foreach (var ei in edgeInfos)
{
if (ei.edge == foundEdge)
{
continue;
}
if (!ei.axis.IsParallel(foundAxis.Value, 0.00001))
{
continue;
}
if (ei.len > edgeLen)
{
opEdge = ei.edge;
edgeLen = ei.len;
opAxis = ei.axis;
}
}
}
return(foundEdge, foundAxis, opEdge, opAxis);
}