/// <summary>
/// Remove vertices that are colinear w/ their two neighbours, within angle tolerance
/// </summary>
public void CollapseFlatVertices(double fMaxDeviationDeg = 5)
{
bool done = false;
int max_passes = 200;
int pass_count = 0;
while (done == false && pass_count++ < max_passes)
{
done = true;
// [RMS] do modulo-indexing here to avoid pathological cases where we do things like
// continually collapse a short edge adjacent to a long edge (which will result in crazy over-collapse)
int N = Graph.MaxVertexID;
const int nPrime = 31337; // any prime will do...
int cur_vid = 0;
do
{
int vid = cur_vid;
cur_vid = (cur_vid + nPrime) % N;
if (!Graph.IsVertex(vid))
{
continue;
}
if (Graph.GetVtxEdgeCount(vid) != 2)
{
continue;
}
double open = Math.Abs(Graph.OpeningAngle(vid));
if (open < 180 - fMaxDeviationDeg)
{
continue;
}
var edges = Graph.GetVtxEdges(vid);
int eid = edges.First();
int eid2 = edges.Last();
if (FixedEdgeFilterF(eid) || FixedEdgeFilterF(eid2))
{
continue;
}
Index2i ev = Graph.GetEdgeV(eid);
int other_v = (ev.a == vid) ? ev.b : ev.a;
DGraph2.EdgeCollapseInfo collapseInfo;
MeshResult result = Graph.CollapseEdge(other_v, vid, out collapseInfo);
if (result == MeshResult.Ok)
{
done = false;
}
else
{
throw new Exception("DGraph2Resampler.CollapseFlatVertices: failed!");
}
} while (cur_vid != 0);
}
}
/// <summary>
/// Decompose graph into simple polylines and polygons.
/// </summary>
public static Curves ExtractCurves(DGraph2 graph)
{
Curves c = new Curves();
c.Loops = new List <Polygon2d>();
c.Paths = new List <PolyLine2d>();
HashSet <int> used = new HashSet <int>();
// find boundary and junction vertices
HashSet <int> boundaries = new HashSet <int>();
HashSet <int> junctions = new HashSet <int>();
foreach (int vid in graph.VertexIndices())
{
if (graph.IsBoundaryVertex(vid))
{
boundaries.Add(vid);
}
if (graph.IsJunctionVertex(vid))
{
junctions.Add(vid);
}
}
// walk paths from boundary vertices
foreach (int start_vid in boundaries)
{
int vid = start_vid;
int eid = graph.GetVtxEdges(vid)[0];
if (used.Contains(eid))
{
continue;
}
PolyLine2d path = new PolyLine2d();
path.AppendVertex(graph.GetVertex(vid));
while (true)
{
used.Add(eid);
Index2i next = NextEdgeAndVtx(eid, vid, graph);
eid = next.a;
vid = next.b;
path.AppendVertex(graph.GetVertex(vid));
if (boundaries.Contains(vid) || junctions.Contains(vid))
{
break; // done!
}
}
c.Paths.Add(path);
}
// ok we should be done w/ boundary verts now...
boundaries.Clear();
foreach (int start_vid in junctions)
{
foreach (int outgoing_eid in graph.VtxEdgesItr(start_vid))
{
if (used.Contains(outgoing_eid))
{
continue;
}
int vid = start_vid;
int eid = outgoing_eid;
PolyLine2d path = new PolyLine2d();
path.AppendVertex(graph.GetVertex(vid));
while (true)
{
used.Add(eid);
Index2i next = NextEdgeAndVtx(eid, vid, graph);
eid = next.a;
vid = next.b;
path.AppendVertex(graph.GetVertex(vid));
if (eid == int.MaxValue || junctions.Contains(vid))
{
break; // done!
}
}
c.Paths.Add(path);
}
}
// all that should be left are continuous loops...
foreach (int start_eid in graph.EdgeIndices())
{
if (used.Contains(start_eid))
{
continue;
}
int eid = start_eid;
Index2i ev = graph.GetEdgeV(eid);
int vid = ev.a;
Polygon2d poly = new Polygon2d();
poly.AppendVertex(graph.GetVertex(vid));
while (true)
{
used.Add(eid);
Index2i next = NextEdgeAndVtx(eid, vid, graph);
eid = next.a;
vid = next.b;
poly.AppendVertex(graph.GetVertex(vid));
if (eid == int.MaxValue || junctions.Contains(vid))
{
throw new Exception("how did this happen??");
}
if (used.Contains(eid))
{
break;
}
}
poly.RemoveVertex(poly.VertexCount - 1);
c.Loops.Add(poly);
}
return(c);
}