/// <summary>
/// Creates an edge if it does not exist, or retrieves an edge with v1 and v2 as points if it does exist
/// </summary>
/// <param name="v1"></param>
/// <param name="v2"></param>
/// <returns></returns>
public Edge CreateOrGet(Vertex v1, Vertex v2)
{
var edge = v1.Edges.FirstOrDefault(o => o.v1 == v2 || o.v2 == v2);
if (edge == null)
edge = CreateEdge(v1, v2);
return edge;
}
/// <summary>
/// Creates an edge
/// </summary>
/// <param name="v1"></param>
/// <param name="v2"></param>
/// <returns></returns>
public Edge CreateEdge(Vertex v1, Vertex v2)
{
Edge result = new Edge() { v1 = v1, v2 = v2 };
v1.Edges.Add(result);
v2.Edges.Add(result);
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>
/// 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>
/// Generate a random vertex within the given boundaries
/// </summary>
/// <param name="xMin"></param>
/// <param name="xMax"></param>
/// <param name="yMin"></param>
/// <param name="yMax"></param>
/// <returns></returns>
public static Vertex RandomVertex(int xMin, int xMax, int yMin, int yMax)
{
var x = RandomGenerator.Next(xMin, xMax);
var y = RandomGenerator.Next(yMin, yMax);
var vertex = new Vertex() { Point = new C2DPoint(x, y)};
return vertex;
}
/// <summary>
/// Splits an edge on a convex polygon into two edges by adding a vertex on a random position
/// While keeping the Convex constraint.
/// </summary>
/// <param name="gm"></param>
/// <param name="e"></param>
/// <param name="maxOffset"></param>
/// <param name="index"></param>
/// <returns></returns>
public static List<Edge> SplitConvexEdge(GraphManager gm, Edge e, int maxOffset, int index)
{
var edgeLine = e.CreateLine();
List<Edge> result = new List<Edge>();
//Create random point on the edge
var offset = Convert.ToDouble(RandomGenerator.Next(0, 100)) / 122 + 0.1;
var point = edgeLine.GetPointOn(offset);
//Calculate offsets
var dx = e.v2.Point.x - e.v1.Point.x;
var dy = e.v2.Point.y - e.v1.Point.y;
//Note swapping offsets for X and Y.
var offsetX = Math.Abs(dx) / (dy);
var offsetY = Math.Abs(dy) / (dx * -1);
//Calculate the maximum endpoint for the new node.
var endPoint = new C2DPoint(offsetX * maxOffset + point.x, offsetY * maxOffset + point.y);
var newLine = new C2DLine(point, endPoint);
var otherVertex1 = e.v1;
var otherVertex2 = e.v2;
var otherEdge1 = otherVertex1.GetOther(e).CreateLine();
var otherEdge2 = otherVertex2.GetOther(e).CreateLine();
//Compare with both other edges, to check if the new vertex would still result in a convex polygon.
//If not, update the maximum offset for the new vertex
if (otherVertex1.GetOther(e) != otherVertex2.GetOther(e))
{
var intersections = new List<C2DPoint>();
otherEdge1.GrowFromCentre(100000000);//Hack: to check if they intersect. The library does not support rays in this case
if (newLine.Crosses(otherEdge1, intersections))
{
var newEndpoint = intersections.Single();
newLine = new C2DLine(point, newEndpoint);
}
intersections = new List<C2DPoint>();
otherEdge2.GrowFromCentre(100000000); //Hack: to check if they intersect. The library does not support rays in this case
if (newLine.Crosses(otherEdge2, intersections))
{
var newEndpoint = intersections.Single();
newLine = new C2DLine(point, newEndpoint);
}
}
//Select a random point on the line (which is bound)
var newlineOffset = Convert.ToDouble(RandomGenerator.Next(0, 100)) / 122+0.1;
var newPoint = newLine.GetPointOn(offset);
var newVertex = new Vertex() { Point = newPoint };
//Indexof might be very slow? Note this is just used for the creation of a testvertex
gm.AddVertexAt(newVertex, gm.Vertices.IndexOf(otherVertex2));
gm.DestroyEdge(e);//Unregister the old edge
result.Add(gm.CreateEdge(otherVertex1, newVertex)); //Add the two new ones
result.Add(gm.CreateEdge(newVertex, otherVertex2)); // :)
return result;
}
/// <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;
}
/// <summary>
/// Inserts a vertex into the list at a specific location
/// </summary>
/// <param name="vertex"></param>
/// <param name="index"></param>
public void AddVertexAt(Vertex vertex, int index)
{
Vertices.Insert(index, vertex);
}
/// <summary>
/// Adds a vertex to the end of the list
/// </summary>
/// <param name="vertex"></param>
public void AddVertex(Vertex vertex)
{
Vertices.Add(vertex);
}
public Edge <TData, TMetric> EdgeForVertex(Vertex <TData, TMetric> vertex)
{
return(Vertices[vertex]);
}
public bool Contains(Vertex <TData, TMetric> vertex)
{
return(Vertices.ContainsKey(vertex));
}