/// <summary>
/// Returns the other triangle than the given triangle on the graph
/// Returns null if no such triangle could be found.
/// </summary>
/// <param name="t"></param>
/// <returns></returns>
public Triangle GetOtherTriangle(Triangle t)
{
var otherVertexOfTriangle = t.GetVertices().Single(o => o != v1 && o != v2);
var triangleMembers = GetTriangleMembers();
//if (triangleMembers.Count() > 2)
//throw new InvalidOperationException("Edge with more than two triangles?");
//TODO: Something goes wrong here! This should never be larger than 1!!!
var otherTriangleMember = triangleMembers.FirstOrDefault(o => o != otherVertexOfTriangle);
if (otherTriangleMember == null)
return null;
var edges = new List<Edge>() { this };
otherTriangleMember.Edges.ForEach(o =>
{
if ((o.v1 == v1 || o.v1 == v2 || o.v2 == v1 || o.v2 == v2))
edges.Add(o);
});
if (edges.Count != 3)
throw new InvalidOperationException("Triangle with no 3 edges");
var triangle = new Triangle() { Edges = edges};
return triangle;
}
/// <summary>
/// Recursively retrieves all conflicting triangles with P based on their circumcircle
/// This method should be O(S) where S is the number of conflicting triangles, which is constant for a convex polygon
/// However due to a bug this seems to be untrue.
/// </summary>
/// <param name="P"></param>
/// <param name="currentTriangle"></param>
/// <param name="SearchNr"></param>
/// <param name="conflicting"></param>
/// <returns></returns>
private List<Triangle> GetRecursiveConflicitingTriangles(Vertex P, Triangle currentTriangle, int SearchNr, Edge conflicting)
{
var result = new List<Triangle>();
if(currentTriangle == null)
return result;
currentTriangle.conflictingEdge = conflicting;
var center = currentTriangle.CreateTriangle().GetCircumCentre();
if (center.Distance(P.Point) <= center.Distance(currentTriangle.Edges[0].v1.Point))
{
//If the circumcircle contains P, add the triangle to the list
result.Add(currentTriangle);
//And continue over all triangles adjecent to the current triangles
foreach (var edge in currentTriangle.Edges)
{
//If the edge was not visited yet, continue
if (!edge.VisitedBy.ContainsKey(SearchNr) || !edge.VisitedBy[SearchNr])
{
edge.VisitedBy[SearchNr] = true;
result.AddRange(GetRecursiveConflicitingTriangles(P, edge.GetOtherTriangle(currentTriangle), SearchNr, edge));
}
}
}
return result;
}
/// <summary>
/// Retriangulate the given triangle with P
/// Basically removes the conflicting edge from the graph and introduces a new one from the vertex that was not on the removed edge and P
/// </summary>
/// <param name="triangle"></param>
/// <param name="P"></param>
private void Retriangulate(Triangle triangle, Vertex P)
{
var otherVertex = triangle.GetVertices().Single(o => o != triangle.conflictingEdge.v1 && o != triangle.conflictingEdge.v2);
GM.DestroyEdge(triangle.conflictingEdge);
GM.CreateOrGet(otherVertex, P);
}
/// <summary>
/// Creates a new triangle on the given vertices
/// Creades the edges if needed
/// Updates references on existing edges
/// </summary>
/// <param name="v1"></param>
/// <param name="v2"></param>
/// <param name="v3"></param>
/// <returns></returns>
public Triangle CreateTriangleAndEdges(Vertex v1, Vertex v2, Vertex v3)
{
var triangle = new Triangle();
var edge1 = CreateOrGet(v1, v2);
var edge2 = CreateOrGet(v2, v3);
var edge3 = CreateOrGet(v3, v1);
triangle.Edges.Add(edge1);
triangle.Edges.Add(edge2);
triangle.Edges.Add(edge3);
return triangle;
}