//
// Extract a minimal cycle or a filament
//
void ExtractPrimitive(Point v0, OrderedPointList heap)
{
List <Point> visited = new List <Point>();
List <Point> sequence = new List <Point>();
sequence.Add(v0);
// Create an initial line as (downward) vertical w.r.t. v0; v1 is based on the vertical line through v0
Point v1 = GetFirstNeighbor(v0); // GetClockwiseMost(new Point("", v0.X, v0.Y + 1), v0);
Point vPrev = v0;
Point vCurr = v1;
int v0Index = graph.IndexOf(v0);
int v1Index = graph.IndexOf(v1);
// Loop until we have a cycle or we have a null (filament)
while (vCurr != null && !vCurr.Equals(v0) && !visited.Contains(vCurr))
{
sequence.Add(vCurr);
visited.Add(vCurr);
Point vNext = GetTightestCounterClockwiseNeighbor(vPrev, vCurr);
vPrev = vCurr;
vCurr = vNext;
}
//
// Filament: hit an endpoint
//
if (vCurr == null)
{
// Filament found, not necessarily rooted at v0.
ExtractFilament(v0, graph.nodes[v0Index].edges[0].target, heap);
}
//
// Minimal cycle found.
//
else if (vCurr.Equals(v0))
{
MinimalCycle primitive = new MinimalCycle();
primitive.AddAll(sequence);
primitives.Add(primitive);
if (Utilities.ATOMIC_REGION_GEN_DEBUG)
{
Debug.WriteLine(primitive.ToString());
}
// Mark that these edges are a part of a cycle
for (int p = 0; p < sequence.Count; p++)
{
graph.MarkCycleEdge(sequence[p], sequence[p + 1 < sequence.Count ? p + 1 : 0]);
}
graph.RemoveEdge(v0, v1);
//
// Check filaments for v0 and v1
//
if (graph.nodes[v0Index].NodeDegree() == 1)
{
// Remove the filament rooted at v0.
ExtractFilament(v0, graph.nodes[v0Index].edges[0].target, heap);
}
//
// indices may have changed; update.
//
v1Index = graph.IndexOf(v1);
if (v1Index != -1)
{
if (graph.nodes[v1Index].NodeDegree() == 1)
{
// Remove the filament rooted at v1.
ExtractFilament(v1, graph.nodes[v1Index].edges[0].target, heap);
}
}
}
//
// vCurr was visited earlier
//
else
{
// 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 (graph.nodes[v0Index].NodeDegree() == 2)
{
// Choose between the the two neighbors
if (graph.nodes[v0Index].edges[0].target.Equals(v1))
{
v1 = v0;
v0 = graph.nodes[v0Index].edges[1].target;
}
else
{
v1 = v0;
v0 = graph.nodes[v0Index].edges[0].target;
}
// Find the next v0 index
v0Index = graph.IndexOf(v0);
}
ExtractFilament(v0, v1, heap);
}
}
//
// Extract a minimal cycle or a filament
//
void ExtractPrimitive(Point v0, OrderedPointList heap)
{
List<Point> visited = new List<Point>();
List<Point> sequence = new List<Point>();
sequence.Add(v0);
// Create an initial line as (downward) vertical w.r.t. v0; v1 is based on the vertical line through v0
Point v1 = GetFirstNeighbor(v0); // GetClockwiseMost(new Point("", v0.X, v0.Y + 1), v0);
Point vPrev = v0;
Point vCurr = v1;
int v0Index = graph.IndexOf(v0);
int v1Index = graph.IndexOf(v1);
// Loop until we have a cycle or we have a null (filament)
while (vCurr != null && !vCurr.Equals(v0) && !visited.Contains(vCurr))
{
sequence.Add(vCurr);
visited.Add(vCurr);
Point vNext = GetTightestCounterClockwiseNeighbor(vPrev, vCurr);
vPrev = vCurr;
vCurr = vNext;
}
//
// Filament: hit an endpoint
//
if (vCurr == null)
{
// Filament found, not necessarily rooted at v0.
ExtractFilament(v0, graph.nodes[v0Index].edges[0].target, heap);
}
//
// Minimal cycle found.
//
else if (vCurr.Equals(v0))
{
MinimalCycle primitive = new MinimalCycle();
primitive.AddAll(sequence);
primitives.Add(primitive);
if (Utilities.ATOMIC_REGION_GEN_DEBUG)
{
Debug.WriteLine(primitive.ToString());
}
// Mark that these edges are a part of a cycle
for (int p = 0; p < sequence.Count; p++)
{
graph.MarkCycleEdge(sequence[p], sequence[p+1 < sequence.Count ? p+1 : 0]);
}
graph.RemoveEdge(v0, v1);
//
// Check filaments for v0 and v1
//
if (graph.nodes[v0Index].NodeDegree() == 1)
{
// Remove the filament rooted at v0.
ExtractFilament(v0, graph.nodes[v0Index].edges[0].target, heap);
}
//
// indices may have changed; update.
//
v1Index = graph.IndexOf(v1);
if (v1Index != -1)
{
if (graph.nodes[v1Index].NodeDegree() == 1)
{
// Remove the filament rooted at v1.
ExtractFilament(v1, graph.nodes[v1Index].edges[0].target, heap);
}
}
}
//
// vCurr was visited earlier
//
else
{
// 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 (graph.nodes[v0Index].NodeDegree() == 2)
{
// Choose between the the two neighbors
if (graph.nodes[v0Index].edges[0].target.Equals(v1))
{
v1 = v0;
v0 = graph.nodes[v0Index].edges[1].target;
}
else
{
v1 = v0;
v0 = graph.nodes[v0Index].edges[0].target;
}
// Find the next v0 index
v0Index = graph.IndexOf(v0);
}
ExtractFilament(v0, v1, heap);
}
}
