/// <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>
/// Find and remove any junction (ie valence>2) vertices of the graph.
/// At a junction, the pair of best-aligned (ie straightest) edges are left
/// connected, and all the other edges are disconnected
///
/// [TODO] currently there is no DGraph2.SetEdge(), so the 'other' edges
/// are deleted and new edges inserted. Hence, edge IDs are not preserved.
/// </summary>
public static int DisconnectJunctions(DGraph2 graph)
{
var junctions = new List <int>();
// find all junctions
foreach (int vid in graph.VertexIndices())
{
if (graph.IsJunctionVertex(vid))
{
junctions.Add(vid);
}
}
foreach (int vid in junctions)
{
Vector2d v = graph.GetVertex(vid);
int[] nbr_verts = graph.VtxVerticesItr(vid).ToArray();
// find best-aligned pair of edges connected to vid
Index2i best_aligned = Index2i.Max; double max_angle = 0;
for (int i = 0; i < nbr_verts.Length; ++i)
{
for (int j = i + 1; j < nbr_verts.Length; ++j)
{
double angle = Vector2d.AngleD(
(graph.GetVertex(nbr_verts[i]) - v).Normalized,
(graph.GetVertex(nbr_verts[j]) - v).Normalized);
angle = Math.Abs(angle);
if (angle > max_angle)
{
max_angle = angle;
best_aligned = new Index2i(nbr_verts[i], nbr_verts[j]);
}
}
}
// for nbr verts that are not part of the best_aligned edges,
// we remove those edges and add a new one connected to a new vertex
for (int k = 0; k < nbr_verts.Length; ++k)
{
if (nbr_verts[k] == best_aligned.a || nbr_verts[k] == best_aligned.b)
{
continue;
}
int eid = graph.FindEdge(vid, nbr_verts[k]);
graph.RemoveEdge(eid, true);
if (graph.IsVertex(nbr_verts[k]))
{
var newpos = Vector2d.Lerp(graph.GetVertex(nbr_verts[k]), v, 0.99);
int newv = graph.AppendVertex(newpos);
graph.AppendEdge(nbr_verts[k], newv);
}
}
}
return(junctions.Count);
}
/// <summary>
/// foreach edge [vid,b] connected to junction vertex vid, remove, add new vertex c,
/// and then add new edge [b,c]. Optionally move c a bit back along edge from vid.
/// </summary>
public static void DisconnectJunction(DGraph2 graph, int vid, double shrinkFactor = 1.0)
{
Vector2d v = graph.GetVertex(vid);
int[] nbr_verts = graph.VtxVerticesItr(vid).ToArray();
for (int k = 0; k < nbr_verts.Length; ++k)
{
int eid = graph.FindEdge(vid, nbr_verts[k]);
graph.RemoveEdge(eid, true);
if (graph.IsVertex(nbr_verts[k]))
{
Vector2d newpos = Vector2d.Lerp(graph.GetVertex(nbr_verts[k]), v, shrinkFactor);
int newv = graph.AppendVertex(newpos);
graph.AppendEdge(nbr_verts[k], newv);
}
}
}
