/// <summary>
/// Adds a new face to the kernel
/// </summary>
/// <param name="positions"></param>
public bool AddFace(IEnumerable <Vec3d> positions)
{
// No bad faces please :(
if (positions.Count() < 3)
{
return(false);
}
// convert positions to vertices inside the mesh
var vertices = VertexQuery.GetVerticesForPositions(_vertices, positions);
// if the positions had stacked vertices, we might not be able to continue
if (vertices.Count() < 3)
{
// iterate over position vertices
foreach (var vertex in vertices)
{
// if the vertex was old, it will have an outgoing
if (vertex.Outgoing != null)
{
continue;
}
// if it was new we need to remove it to restore state
Remove(vertex);
}
return(false);
}
var edges = new List <HalfEdge>();
// iterate over all positions
foreach (var vertex in vertices)
{
// create a new halfedge originating from the current vertex and linked to the new face
var halfEdge = new HalfEdge
{
Origin = vertex,
};
// test if the vertex already has an outgoing edge assigned
if (vertex.Outgoing is null)
{
vertex.Outgoing = halfEdge;
}
edges.Add(halfEdge);
}
// Insert a face from the edges
Insert(edges);
// iterate over all edges and insert them
foreach (var edge in edges)
{
// TODO: Maybe we should NOT skip linking checks here
_halfEdges.Add(edge);
}
// test if first face
if (this.FaceCount == 1)
{
var outerRing = new EdgeIterator(
_halfEdges[0])
.Select(h => h.Pair)
.Reverse()
.ToList();
// establish circular link between outside half-edges
EdgeLinker.LinkOrderedEdgeCollection(outerRing);
}
// TODO: Should be method of edgelinker instead
// Make sure edge pairs either have a starting face or the ghost face
// Iterators are lazy, calling `Count()` will execute the select body
_ = edges.Where(e => e.Pair.Face == null).Select(e => e.Pair.Face = Kernel.Outside).Count();
return(true);
// TODO: Make sure outer halfEdges are linked,too
// TODO: Right now only inner halfEdges are linked circularly
// TODO: This leads to crashes on faces with too many naked edges when creating vertexringiterators
// TODO: For this we will need a 'ghost' face that encompasses all the space outside of the mesh faces
// TODO: CLosed meshes will have an empty ghost face
}