/// <summary>
/// insert new point into segment eid at parameter value t
/// If t is within tol of endpoint of segment, we use that instead.
/// </summary>
protected Index2i split_segment_at_t(int eid, double t, double tol)
{
Index2i ev = Graph.GetEdgeV(eid);
Segment2d seg = new Segment2d(Graph.GetVertex(ev.a), Graph.GetVertex(ev.b));
int use_vid = -1;
int new_eid = -1;
if (t < -(seg.Extent - tol))
{
use_vid = ev.a;
}
else if (t > (seg.Extent - tol))
{
use_vid = ev.b;
}
else
{
DGraph2.EdgeSplitInfo splitInfo;
MeshResult result = Graph.SplitEdge(eid, out splitInfo);
if (result != MeshResult.Ok)
{
throw new Exception("insert_into_segment: edge split failed?");
}
use_vid = splitInfo.vNew;
new_eid = splitInfo.eNewBN;
Vector2d pt = seg.PointAt(t);
Graph.SetVertex(use_vid, pt);
PointHash.InsertPointUnsafe(splitInfo.vNew, pt);
}
return(new Index2i(use_vid, new_eid));
}
public void CollapseToMinEdgeLength(double fMinLen)
{
double sharp_threshold_deg = 140.0f;
double minLenSqr = fMinLen * fMinLen;
bool done = false;
int max_passes = 100;
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.MaxEdgeID;
const int nPrime = 31337; // any prime will do...
int cur_eid = 0;
do
{
int eid = cur_eid;
cur_eid = (cur_eid + nPrime) % N;
if (!Graph.IsEdge(eid))
{
continue;
}
if (FixedEdgeFilterF(eid))
{
continue;
}
Index2i ev = Graph.GetEdgeV(eid);
Vector2d va = Graph.GetVertex(ev.a);
Vector2d vb = Graph.GetVertex(ev.b);
double distSqr = va.DistanceSquared(vb);
if (distSqr < minLenSqr)
{
int vtx_idx = -1; // collapse to this vertex
// check valences. want to preserve positions of non-valence-2
int na = Graph.GetVtxEdgeCount(ev.a);
int nb = Graph.GetVtxEdgeCount(ev.b);
if (na != 2 && nb != 2)
{
continue;
}
if (na != 2)
{
vtx_idx = 0;
}
else if (nb != 2)
{
vtx_idx = 1;
}
// check opening angles. want to preserve sharp(er) angles
if (vtx_idx == -1)
{
double opena = Math.Abs(Graph.OpeningAngle(ev.a));
double openb = Math.Abs(Graph.OpeningAngle(ev.b));
if (opena < sharp_threshold_deg && openb < sharp_threshold_deg)
{
continue;
}
else if (opena < sharp_threshold_deg)
{
vtx_idx = 0;
}
else if (openb < sharp_threshold_deg)
{
vtx_idx = 1;
}
}
Vector2d newPos = (vtx_idx == -1) ? 0.5 * (va + vb) : ((vtx_idx == 0) ? va : vb);
int keep = ev.a, remove = ev.b;
if (vtx_idx == 1)
{
remove = ev.a; keep = ev.b;
}
DGraph2.EdgeCollapseInfo collapseInfo;
if (Graph.CollapseEdge(keep, remove, out collapseInfo) == MeshResult.Ok)
{
Graph.SetVertex(collapseInfo.vKept, newPos);
done = false;
}
}
} while (cur_eid != 0);
}
}
protected virtual void do_split(Line2d line, bool insert_edges, int insert_gid)
{
if (EdgeSigns.Length < Graph.MaxVertexID)
{
EdgeSigns.resize(Graph.MaxVertexID);
}
foreach (int vid in Graph.VertexIndices())
{
EdgeSigns[vid] = line.WhichSide(Graph.GetVertex(vid), OnVertexTol);
}
hits.Clear();
foreach (int eid in Graph.EdgeIndices())
{
Index2i ev = Graph.GetEdgeV(eid);
var signs = new Index2i(EdgeSigns[ev.a], EdgeSigns[ev.b]);
if (signs.a * signs.b > 0)
{
continue; // both positive or negative, ignore
}
var hit = new edge_hit()
{
hit_eid = eid, vtx_signs = signs, hit_vid = -1
};
Vector2d a = Graph.GetVertex(ev.a);
Vector2d b = Graph.GetVertex(ev.b);
// parallel-edge case (both are zero)
if (signs.a == signs.b)
{
if (a.DistanceSquared(b) > MathUtil.Epsilon)
{
// we need to somehow not insert a new segment for this span below.
// so, insert two hit points for the ray-interval, with same eid.
// This will result in this span being skipped by the same-eid test below
// *however*, if other edges self-intersect w/ this segment, this will *not work*
// and duplicate edges will be inserted
hit.hit_vid = ev.a;
hit.line_t = line.Project(a);
hits.Add(hit);
hit.hit_vid = ev.b;
hit.line_t = line.Project(b);
hits.Add(hit);
}
else
{
// degenerate edge - fall through to a == 0 case below
signs.b = 1;
}
}
if (signs.a == 0)
{
hit.hit_pos = a;
hit.hit_vid = ev.a;
hit.line_t = line.Project(a);
}
else if (signs.b == 0)
{
hit.hit_pos = b;
hit.hit_vid = ev.b;
hit.line_t = line.Project(b);
}
else
{
var intr = new IntrLine2Segment2(line, new Segment2d(a, b));
if (intr.Find() == false)
{
throw new Exception("GraphSplitter2d.Split: signs are different but ray did not it?");
}
if (intr.IsSimpleIntersection)
{
hit.hit_pos = intr.Point;
hit.line_t = intr.Parameter;
}
else
{
throw new Exception("GraphSplitter2d.Split: got parallel edge case!");
}
}
hits.Add(hit);
}
// sort by increasing ray-t
hits.Sort((hit0, hit1) => { return(hit0.line_t.CompareTo(hit1.line_t)); });
// insert segments between successive intersection points
int N = hits.Count;
for (int i = 0; i < N - 1; ++i)
{
int j = i + 1;
// note: skipping parallel segments depends on this eid == eid test (see above)
if (hits[i].line_t == hits[j].line_t || hits[i].hit_eid == hits[j].hit_eid)
{
continue;
}
int vi = hits[i].hit_vid;
int vj = hits[j].hit_vid;
if (vi == vj && vi >= 0)
{
continue;
}
if (vi >= 0 && vj >= 0)
{
int existing = Graph.FindEdge(vi, vj);
if (existing >= 0)
{
continue;
}
}
if (vi == -1)
{
DGraph2.EdgeSplitInfo split;
var result = Graph.SplitEdge(hits[i].hit_eid, out split);
if (result != MeshResult.Ok)
{
throw new Exception("GraphSplitter2d.Split: first edge split failed!");
}
vi = split.vNew;
Graph.SetVertex(vi, hits[i].hit_pos);
edge_hit tmp = hits[i]; tmp.hit_vid = vi; hits[i] = tmp;
}
if (vj == -1)
{
DGraph2.EdgeSplitInfo split;
var result = Graph.SplitEdge(hits[j].hit_eid, out split);
if (result != MeshResult.Ok)
{
throw new Exception("GraphSplitter2d.Split: second edge split failed!");
}
vj = split.vNew;
Graph.SetVertex(vj, hits[j].hit_pos);
edge_hit tmp = hits[j]; tmp.hit_vid = vj; hits[j] = tmp;
}
// check if we actually want to add this segment
if (InsideTestF != null)
{
Vector2d midpoint = 0.5 * (Graph.GetVertex(vi) + Graph.GetVertex(vj));
if (InsideTestF(midpoint) == false)
{
continue;
}
}
if (insert_edges)
{
Graph.AppendEdge(vi, vj, insert_gid);
}
}
}