//--------------------------------------------------------------------------------------------------
public static bool ComputeAxisFromVertex(TopoDS_Face face, TopoDS_Vertex vertex, out Ax1 axis)
{
// Get normal at point of vertex
var uv = BRep_Tool.Parameters(vertex, face);
Pnt centerPoint = Pnt.Origin;
Vec faceNormal = Vec.Zero;
new BRepGProp_Face(face).Normal(uv.X, uv.Y, ref centerPoint, ref faceNormal);
// Find edges
var edges = face.Edges(false).Where(edge => edge.Vertices().ContainsSame(vertex)).ToList();
if (edges.Count != 2)
{
axis = new Ax1();
return(false);
}
// Calc direction
bool order = false; // is false if face is on the left of edge1
var tangents = new Vec[2];
for (var edgeIndex = 0; edgeIndex < edges.Count; edgeIndex++)
{
var edge = edges[edgeIndex];
var edgeAdaptor = edge.Adaptor();
var parameter = BRep_Tool.Parameter(vertex, edge);
Pnt unusedPoint = Pnt.Origin;
Vec edgeTangent = Vec.Zero;
edgeAdaptor.D1(parameter, ref unusedPoint, ref edgeTangent);
var parameterReversed = parameter > (edgeAdaptor.FirstParameter() + edgeAdaptor.LastParameter()) * 0.5;
if (parameterReversed)
{
edgeTangent.Reverse();
}
if (edgeIndex == 0 && parameterReversed != (edge.Orientation() == TopAbs_Orientation.TopAbs_REVERSED))
{
order = true; // face is on the right of edge1
}
tangents[edgeIndex] = edgeTangent.Normalized();
}
var direction = tangents[0].Added(tangents[1]);
var angleBetweenTangents = tangents[0].AngleWithRef(tangents[1], faceNormal);
if (order)
{
angleBetweenTangents *= -1.0;
}
if (angleBetweenTangents < 0)
{
// Concave vertex
direction.Reverse();
}
axis = new Ax1(centerPoint, direction.ToDir());
return(true);
}