public MeshResult FlipEdge(int vA, int vB, out EdgeFlipInfo flip)
{
int eid = find_edge(vA, vB);
if (eid == InvalidID)
{
flip = new EdgeFlipInfo();
return(MeshResult.Failed_NotAnEdge);
}
return(FlipEdge(eid, out flip));
}
public MeshResult FlipEdge(int eab, out EdgeFlipInfo flip)
{
flip = new EdgeFlipInfo();
if (!IsEdge(eab))
{
return(MeshResult.Failed_NotAnEdge);
}
if (edge_is_boundary(eab))
{
return(MeshResult.Failed_IsBoundaryEdge);
}
// find oriented edge [a,b], tris t0,t1, and other verts c in t0, d in t1
int eab_i = 4 * eab;
int a = edges[eab_i], b = edges[eab_i + 1];
int t0 = edges[eab_i + 2], t1 = edges[eab_i + 3];
int[] T0tv = GetTriangle(t0).array;
int[] T1tv = GetTriangle(t1).array;
int c = IndexUtil.orient_tri_edge_and_find_other_vtx(ref a, ref b, T0tv);
int d = IndexUtil.find_tri_other_vtx(a, b, T1tv);
if (c == InvalidID || d == InvalidID)
{
return(MeshResult.Failed_BrokenTopology);
}
int flipped = find_edge(c, d);
if (flipped != InvalidID)
{
return(MeshResult.Failed_FlippedEdgeExists);
}
// find edges bc, ca, ad, db
int ebc = find_tri_neighbour_edge(t0, b, c);
int eca = find_tri_neighbour_edge(t0, c, a);
int ead = find_tri_neighbour_edge(t1, a, d);
int edb = find_tri_neighbour_edge(t1, d, b);
// update triangles
set_triangle(t0, c, d, b);
set_triangle(t1, d, c, a);
// update edge AB, which becomes flipped edge CD
set_edge_vertices(eab, c, d);
set_edge_triangles(eab, t0, t1);
int ecd = eab;
// update the two other edges whose triangle nbrs have changed
if (replace_edge_triangle(eca, t0, t1) == -1)
{
throw new ArgumentException("DMesh3.FlipEdge: first replace_edge_triangle failed");
}
if (replace_edge_triangle(edb, t1, t0) == -1)
{
throw new ArgumentException("DMesh3.FlipEdge: second replace_edge_triangle failed");
}
// update triangle nbr lists (these are edges)
set_triangle_edges(t0, ecd, edb, ebc);
set_triangle_edges(t1, ecd, eca, ead);
// remove old eab from verts a and b, and decrement ref counts
if (vertex_edges[a].Remove(eab) == false)
{
throw new ArgumentException("DMesh3.FlipEdge: first vertex_edges remove failed");
}
if (vertex_edges[b].Remove(eab) == false)
{
throw new ArgumentException("DMesh3.FlipEdge: second vertex_edges remove failed");
}
vertices_refcount.decrement(a);
vertices_refcount.decrement(b);
if (IsVertex(a) == false || IsVertex(b) == false)
{
throw new ArgumentException("DMesh3.FlipEdge: either a or b is not a vertex?");
}
// add new edge ecd to verts c and d, and increment ref counts
vertex_edges[c].Add(ecd);
vertex_edges[d].Add(ecd);
vertices_refcount.increment(c);
vertices_refcount.increment(d);
// success! collect up results
flip.eID = eab;
flip.v0 = a; flip.v1 = b;
flip.ov0 = c; flip.ov1 = d;
flip.t0 = t0; flip.t1 = t1;
updateTimeStamp(true);
return(MeshResult.Ok);
}
