/// <summary>
/// Inserts a new Vertex between two given exsisting Vertices.
/// </summary>
/// <param name="geometry">The Geometry to insert a Vertex.</param>
/// <param name="p">Handle of Vertex one.</param>
/// <param name="q">Handle of Vertex two.</param>
/// <param name="pos">Position of the new Vertex</param>
/// <returns>New Vertex Handle.</returns>
public static int InsertVertex(this Geometry geometry, int p, int q, float3 pos)
{
var adjacentVertices = geometry.GetVertexAdjacentVertices(p).ToList();
for (var i = 0; i < adjacentVertices.Count; i++)
{
if (adjacentVertices[i].Handle == q)
{
break;
}
if (i == adjacentVertices.Count - 1)
{
throw new ArgumentException("Vertices with Handle q=" + q + " and p=" + p + " are not adjacent!");
}
}
var newVertex = new Vertex(geometry.CreateVertHandleId(), pos);
//add two new Half Edges
var newHalfEdge1 = new HalfEdge(geometry.CreateHalfEdgeHandleId());
var newHalfEdge2 = new HalfEdge(geometry.CreateHalfEdgeHandleId());
//set origin to new Vertex
newHalfEdge1.OriginVertex = newVertex.Handle;
newHalfEdge2.OriginVertex = newVertex.Handle;
newVertex.IncidentHalfEdge = newHalfEdge2.Handle;
var vertexP = geometry.GetVertexByHandle(p);
var vertexQ = geometry.GetVertexByHandle(q);
//Find Half Edge between p and q
var incomingEdges = geometry.GetVertexStartingHalfEdges(vertexP.Handle);
var he1 = new HalfEdge();
var he2 = new HalfEdge();
foreach (var halfEdge in incomingEdges)
{
var twinEdge = geometry.GetHalfEdgeByHandle(halfEdge.TwinHalfEdge);
if (twinEdge.OriginVertex != vertexQ.Handle)
{
continue;
}
he1 = halfEdge;
he2 = twinEdge;
}
var next1 = geometry.GetHalfEdgeByHandle(he2.NextHalfEdge);
var next2 = geometry.GetHalfEdgeByHandle(he1.NextHalfEdge);
//change Handels
he1.TwinHalfEdge = newHalfEdge1.Handle;
newHalfEdge1.TwinHalfEdge = he1.Handle;
newHalfEdge1.NextHalfEdge = he2.NextHalfEdge;
he2.NextHalfEdge = newHalfEdge1.Handle;
newHalfEdge1.PrevHalfEdge = he2.Handle;
next1.PrevHalfEdge = newHalfEdge1.Handle;
he2.TwinHalfEdge = newHalfEdge2.Handle;
newHalfEdge2.TwinHalfEdge = he2.Handle;
newHalfEdge2.NextHalfEdge = he1.NextHalfEdge;
he1.NextHalfEdge = newHalfEdge2.Handle;
newHalfEdge2.PrevHalfEdge = he1.Handle;
next2.PrevHalfEdge = newHalfEdge2.Handle;
//reconnect faces
newHalfEdge1.IncidentFace = he2.IncidentFace;
newHalfEdge2.IncidentFace = he1.IncidentFace;
//replace exsisnting Edges
geometry.ReplaceHalfEdge(he1);
geometry.ReplaceHalfEdge(he2);
geometry.ReplaceHalfEdge(next1);
geometry.ReplaceHalfEdge(next2);
//add to dict
geometry.DictVertices.Add(newVertex.Handle, newVertex);
geometry.DictHalfEdges.Add(newHalfEdge1.Handle, newHalfEdge1);
geometry.DictHalfEdges.Add(newHalfEdge2.Handle, newHalfEdge2);
return(newVertex.Handle);
}
