/// <summary>
/// Gets a list of node pairs that represent unique edges in the graph
/// </summary>
/// <returns>List of unordered pairs containing boundary nodes</returns>
public List <UnorderedPair <BoundaryGraphNode, BoundaryGraphNode> > getEdgesAsUniquePairs()
{
// Find each unique edge as a pair of nodes using hashset
HashSet <UnorderedPair <BoundaryGraphNode, BoundaryGraphNode> > edges = new HashSet <UnorderedPair <BoundaryGraphNode, BoundaryGraphNode> >();
foreach (BoundaryGraphNode node1 in this)
{
foreach (BoundaryGraphNode node2 in this)
{
// If they are equal skip
if (node1 == node2)
{
continue;
}
// If they are not neighbors, skip
if (!node1.HasNeighbor(node2))
{
continue;
}
UnorderedPair <BoundaryGraphNode, BoundaryGraphNode> temp = new UnorderedPair <BoundaryGraphNode, BoundaryGraphNode>(node1, node2);
edges.Add(temp);
}
}
// Convert to list and return
return(new List <UnorderedPair <BoundaryGraphNode, BoundaryGraphNode> >(edges));
}
// Follows MSDN spec
public override bool Equals(object obj)
{
// If null or non castable, return false
if (obj == null)
{
return(false);
}
UnorderedPair <T1, T2> other = obj as UnorderedPair <T1, T2>;
if (other == null)
{
return(false);
}
return((item1.Equals(other.item1) && item2.Equals(other.item2)) || (item2.Equals(other.item1) && item1.Equals(other.item2)));
}
// Checks existing graph for any intersections, then splits the edges that intersect
// By a node with a parent to each boundary that caused the intersection
public void Unify()
{
List <UnorderedPair <BoundaryGraphNode, BoundaryGraphNode> > edges = getEdgesAsUniquePairs();
// Intersect each edge using Line2D and split the edges
int i, j;
for (i = 0; i < edges.Count; i++)
{
UnorderedPair <BoundaryGraphNode, BoundaryGraphNode> edge1 = edges[i];
// Build the first line
Line2D line1 = new Line2D(edge1.item1.position, edge1.item2.position);
for (j = i; j < edges.Count; j++)
{
UnorderedPair <BoundaryGraphNode, BoundaryGraphNode> edge2 = edges[j];
// Skip if they are the same edge
if (i == j)
{
continue;
}
// Skip if these edges are already neighbors (share a common vertex)
// because they already intersect at that common vertex
if (edge1.item1 == edge2.item1 || edge1.item1 == edge2.item2 || edge1.item2 == edge2.item1 || edge1.item2 == edge2.item2)
{
continue;
}
// NOTE: no need to equals test since this is a set of unique unordered pairs
Line2D line2 = new Line2D(edge2.item1.position, edge2.item2.position);
// test for intersection
Vector2 intersection;
if (line1.Intersect(line2, out intersection))
{
// Create intersection node and split edges
BoundaryGraphNode intersectionNode = new BoundaryGraphNode(intersection);
intersectionNode.AddParentBoundary(edge1.item1.GetParentBoundaries()[0]);
intersectionNode.AddParentBoundary(edge2.item1.GetParentBoundaries()[0]);
AddNode(intersectionNode);
// Remove neighbors
edge1.item1.RemoveNeighbor(edge1.item2); // Method auto removes the reciprical relation too
edge2.item1.RemoveNeighbor(edge2.item2);
// Rejoin the verticies to intersection
intersectionNode.AddNeighbor(edge1.item1);
intersectionNode.AddNeighbor(edge1.item2);
intersectionNode.AddNeighbor(edge2.item1);
intersectionNode.AddNeighbor(edge2.item2);
// Now we need to update our edges list so future runs of the loop interact with the new edges not the old ones
edges.Remove(edge1);
edges.Remove(edge2);
// Decrement outter loop because we are removing the current index
i--;
// Add in the new edges we just formed.
edges.Add(new UnorderedPair <BoundaryGraphNode, BoundaryGraphNode>(edge1.item1, intersectionNode));
edges.Add(new UnorderedPair <BoundaryGraphNode, BoundaryGraphNode>(edge1.item2, intersectionNode));
edges.Add(new UnorderedPair <BoundaryGraphNode, BoundaryGraphNode>(edge2.item1, intersectionNode));
edges.Add(new UnorderedPair <BoundaryGraphNode, BoundaryGraphNode>(edge2.item2, intersectionNode));
/* Deeper explanation:
* We are removing the edge at index i, meaning that i+1 will become i. In order to not skip over i+1,
* we decrement i by 1 so when the loop restarts, new i = i + 1 = old i
* then we must immediately break the current inner loop since we are no longer matching intersections
* against edge i, since we just found one and removed that edge from the list
*/
break;
}
}
}
}
