public static Node GetCounterClockwiseMostAdjacent(Node prev, Node curr, ref List <Node> _nodes)
{
if (curr.adjacents == null || curr.adjacents.Count == 0)
{
return(null);
}
Vector3 dirCurr = Vector3.zero;
dirCurr = curr.Position - prev.Position;
Node next = EdgeGraphUtility.GetNode(curr.GetAdjacent(prev.ID), ref _nodes);
if (next == null)
{
return(null);
}
Vector3 dirNext = next.Position - curr.Position;
bool currIsConvex = DotPerp(dirNext, dirCurr) <= 0;
foreach (var a in curr.adjacents)
{
var adj = EdgeGraphUtility.GetNode(a, ref _nodes);
Vector3 dirAdj = adj.Position - curr.Position;
if (currIsConvex)
{
if (DotPerp(dirCurr, dirAdj) > 0 && DotPerp(dirNext, dirAdj) > 0)
{
next = adj;
dirNext = dirAdj;
currIsConvex = DotPerp(dirNext, dirCurr) <= 0;
}
}
else
{
if (DotPerp(dirCurr, dirAdj) > 0 || DotPerp(dirNext, dirAdj) > 0)
{
next = adj;
dirNext = dirAdj;
currIsConvex = DotPerp(dirNext, dirCurr) <= 0;
}
}
}
return(next);
}
// Algorithms from http://www.geometrictools.com/Documentation/MinimalCycleBasis.pdf
// The Minimal Cycle Basis for a Planar Graph by David Eberly
/// <summary>
/// Attempts to find minimal cycles
/// </summary>
public static void ExtractPrimitive(Node _n0, ref List <Node> _nodes, ref List <Edge> _edges, ref List <Primitive> _primitives)
{
List <Node> visited = new List <Node>();
List <Node> sequence = new List <Node>();
EdgeGraphUtility.CheckAdjacentNodes(ref _nodes, ref _edges);
if (_n0.adjacents.Count == 0)
{
EdgeGraphUtility.RemoveNodeAndCleanAdjacents(_n0, ref _nodes, ref _edges);
return;
}
sequence.Add(_n0);
Node _n1 = GetClockwiseMostAdjacent(null, _n0, ref _nodes);
Node prev = _n0;
Node curr = _n1;
while (curr != null && curr != _n0 && !visited.Contains(curr))
{
sequence.Add(curr);
visited.Add(curr);
Node next = GetCounterClockwiseMostAdjacent(prev, curr, ref _nodes);
prev = curr;
curr = next;
}
if (curr == null)
{
// Filament found, not necessarily rooted at prev
ExtractFilament(prev, EdgeGraphUtility.GetNode(prev.adjacents[0], ref _nodes), ref _nodes, ref _edges, ref _primitives);
}
else if (curr == _n0)
{
// Minimal cycle found
Primitive primitive = new Primitive(Primitive.PrimitiveType.MinimalCycle);
primitive.nodes.AddRange(sequence);
for (int i = 0; i < sequence.Count; i++)
{
Node n1;
Node n2;
if (i == sequence.Count - 1)
{
n1 = sequence[i];
n2 = sequence[0];
}
else
{
n1 = sequence[i];
n2 = sequence[i + 1];
}
Edge e = EdgeGraphUtility.FindEdgeByNodes(n1, n2, _edges);
if (e != null)
{
primitive.edges.Add(e);
e.isPartOfCycle = true;
}
}
EdgeGraphUtility.RemoveEdgeAndCleanAdjacents(_n0, _n1, ref _nodes, ref _edges);
if (_n0.adjacents.Count == 1)
{
// Remove the filament rooted at v0
ExtractFilament(_n0, EdgeGraphUtility.GetNode(_n0.adjacents[0], ref _nodes), ref _nodes, ref _edges, ref _primitives);
}
if (_n1.adjacents.Count == 1)
{
// Remove the filament rooted at v1
ExtractFilament(_n1, EdgeGraphUtility.GetNode(_n1.adjacents[0], ref _nodes), ref _nodes, ref _edges, ref _primitives);
}
_primitives.Add(primitive);
}
else // curr was visited earlier
{
// A cycle has been found, but is not guaranteed to be a minimal cycle.
// This implies v0 is part of a filament
// Locate the starting point for the filament by traversing from v0 away from the initial v1
while (_n0.adjacents.Count == 2)
{
if (_n0.adjacents[0] != _n1.ID)
{
_n1 = _n0;
_n0 = EdgeGraphUtility.GetNode(_n0.adjacents[0], ref _nodes);
}
else
{
_n1 = _n0;
_n0 = EdgeGraphUtility.GetNode(_n0.adjacents[1], ref _nodes);
}
}
ExtractFilament(_n0, _n1, ref _nodes, ref _edges, ref _primitives);
}
}
/// <summary>
/// Extracts filament consisting of nodes and edges
/// </summary>
public static void ExtractFilament(Node _n0, Node _n1, ref List <Node> _nodes, ref List <Edge> _edges, ref List <Primitive> _primitives)
{
Edge e = EdgeGraphUtility.FindEdgeByNodes(_n0, _n1, _edges);
if (e != null && e.isPartOfCycle)
{
if (_n0.adjacents.Count >= 3)
{
EdgeGraphUtility.RemoveEdgeAndCleanAdjacents(_n0, _n1, ref _nodes, ref _edges);
_n0 = _n1;
if (_n0.adjacents.Count == 1)
{
_n1 = EdgeGraphUtility.GetNode(_n0.adjacents[0], ref _nodes);
}
}
while (_n0.adjacents.Count == 1)
{
_n1 = EdgeGraphUtility.GetNode(_n0.adjacents[0], ref _nodes);
Edge ee = EdgeGraphUtility.FindEdgeByNodes(_n0, _n1, _edges);
if (ee != null && e.isPartOfCycle)
{
EdgeGraphUtility.RemoveNodeAndCleanAdjacents(_n0, ref _nodes, ref _edges);
EdgeGraphUtility.RemoveEdgeAndCleanAdjacents(_n0, _n1, ref _nodes, ref _edges);
}
else
{
break;
}
}
if (_n0.adjacents.Count == 0)
{
EdgeGraphUtility.RemoveNodeAndCleanAdjacents(_n0, ref _nodes, ref _edges);
}
}
else
{
Primitive primitive = new Primitive(Primitive.PrimitiveType.Filament);
if (_n0.adjacents.Count >= 3)
{
primitive.nodes.Add(_n0);
primitive.edges.Add(e);
EdgeGraphUtility.RemoveEdgeAndCleanAdjacents(_n0, _n1, ref _nodes, ref _edges);
_n0 = _n1;
if (_n0.adjacents.Count == 1)
{
_n1 = EdgeGraphUtility.GetNode(_n0.adjacents[0], ref _nodes);
}
}
while (_n0.adjacents.Count == 1)
{
primitive.nodes.Add(_n0);
_n1 = EdgeGraphUtility.GetNode(_n0.adjacents[0], ref _nodes);
EdgeGraphUtility.RemoveNodeAndCleanAdjacents(_n0, ref _nodes, ref _edges);
Edge _e = EdgeGraphUtility.RemoveEdgeAndCleanAdjacents(_n0, _n1, ref _nodes, ref _edges);
if (_e != null)
{
primitive.edges.Add(_e);
}
_n0 = _n1;
}
primitive.nodes.Add(_n0);
if (_n0.adjacents.Count == 0)
{
EdgeGraphUtility.RemoveNodeAndCleanAdjacents(_n0, ref _nodes, ref _edges);
}
_primitives.Add(primitive);
}
}
