// return same indices as GetEdgeV, but oriented based on attached triangle
Index2i get_oriented_edgev(int eID, int tid_in, int tid_out)
{
Index2i edgev = Mesh.GetEdgeV(eID);
int a = edgev.a, b = edgev.b;
Index3i tri = Mesh.GetTriangle(tid_in);
int ai = IndexUtil.find_edge_index_in_tri(a, b, ref tri);
return(new Index2i(tri[ai], tri[(ai + 1) % 3]));
}
public virtual bool Cut()
{
double invalidDist = double.MinValue;
// compute signs
int MaxVID = Mesh.MaxVertexID;
double[] signs = new double[MaxVID];
gParallel.ForEach(Interval1i.Range(MaxVID), (vid) => {
if (Mesh.IsVertex(vid))
{
Vector3D v = Mesh.GetVertex(vid);
signs[vid] = (v - PlaneOrigin).Dot(PlaneNormal);
}
else
{
signs[vid] = invalidDist;
}
});
HashSet <int> ZeroEdges = new HashSet <int>();
HashSet <int> ZeroVertices = new HashSet <int>();
HashSet <int> OnCutEdges = new HashSet <int>();
// have to skip processing of new edges. If edge id
// is > max at start, is new. Otherwise if in NewEdges list, also new.
int MaxEID = Mesh.MaxEdgeID;
HashSet <int> NewEdges = new HashSet <int>();
// cut existing edges with plane, using edge split
for (int eid = 0; eid < MaxEID; ++eid)
{
if (Mesh.IsEdge(eid) == false)
{
continue;
}
if (eid >= MaxEID || NewEdges.Contains(eid))
{
continue;
}
Index2i ev = Mesh.GetEdgeV(eid);
double f0 = signs[ev.a];
double f1 = signs[ev.b];
// If both signs are 0, this edge is on-contour
// If one sign is 0, that vertex is on-contour
int n0 = (Math.Abs(f0) < math.MathUtil.Epsilon) ? 1 : 0;
int n1 = (Math.Abs(f1) < math.MathUtil.Epsilon) ? 1 : 0;
if (n0 + n1 > 0)
{
if (n0 + n1 == 2)
{
ZeroEdges.Add(eid);
}
else
{
ZeroVertices.Add((n0 == 1) ? ev[0] : ev[1]);
}
continue;
}
// no crossing
if (f0 * f1 > 0)
{
continue;
}
NGonsCore.geometry3Sharp.mesh.DMesh3.EdgeSplitInfo splitInfo;
MeshResult result = Mesh.SplitEdge(eid, out splitInfo);
if (result != MeshResult.Ok)
{
throw new Exception("MeshPlaneCut.Cut: failed in SplitEdge");
//return false;
}
// SplitEdge just bisects edge - use plane intersection instead
double t = f0 / (f0 - f1);
Vector3D newPos = (1 - t) * Mesh.GetVertex(ev.a) + (t) * Mesh.GetVertex(ev.b);
Mesh.SetVertex(splitInfo.vNew, newPos);
NewEdges.Add(splitInfo.eNewBN);
NewEdges.Add(splitInfo.eNewCN); OnCutEdges.Add(splitInfo.eNewCN);
if (splitInfo.eNewDN != NGonsCore.geometry3Sharp.mesh.DMesh3.InvalidID)
{
NewEdges.Add(splitInfo.eNewDN);
OnCutEdges.Add(splitInfo.eNewDN);
}
}
// remove one-rings of all positive-side vertices.
for (int i = 0; i < signs.Length; ++i)
{
if (signs[i] > 0 && Mesh.IsVertex(i))
{
Mesh.RemoveVertex(i, true, false);
}
}
// ok now we extract boundary loops, but restricted
// to either the zero-edges we found, or the edges we created! bang!!
Func <int, bool> CutEdgeFilterF = (eid) => {
if (OnCutEdges.Contains(eid) || ZeroEdges.Contains(eid))
{
return(true);
}
return(false);
};
try {
MeshBoundaryLoops loops = new MeshBoundaryLoops(Mesh, false);
loops.EdgeFilterF = CutEdgeFilterF;
loops.Compute();
CutLoops = loops.Loops;
CutLoopsFailed = false;
} catch {
CutLoops = new List <EdgeLoop>();
CutLoopsFailed = true;
}
return(true);
} // Cut()