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);
}
public MeshResult SplitEdge(int eab, out EdgeSplitInfo split)
{
split = new EdgeSplitInfo();
if (!IsEdge(eab))
{
return(MeshResult.Failed_NotAnEdge);
}
// look up primary edge & triangle
int eab_i = 4 * eab;
int a = edges[eab_i], b = edges[eab_i + 1];
int t0 = edges[eab_i + 2];
if (t0 == InvalidID)
{
return(MeshResult.Failed_BrokenTopology);
}
Index3i T0tv = GetTriangle(t0);
int[] T0tv_array = T0tv.array;
int c = IndexUtil.orient_tri_edge_and_find_other_vtx(ref a, ref b, T0tv_array);
// create new vertex
Vector3d vNew = 0.5 * (GetVertex(a) + GetVertex(b));
int f = AppendVertex(vNew);
// quite a bit of code is duplicated between boundary and non-boundary case, but it
// is too hard to follow later if we factor it out...
if (edge_is_boundary(eab))
{
// look up edge bc, which needs to be modified
Index3i T0te = GetTriEdges(t0);
int ebc = T0te[IndexUtil.find_edge_index_in_tri(b, c, T0tv_array)];
// rewrite existing triangle
replace_tri_vertex(t0, b, f);
// add new second triangle
int t2 = add_triangle_only(f, b, c, InvalidID, InvalidID, InvalidID);
if (triangle_groups != null)
{
triangle_groups.insert(triangle_groups[t0], t2);
}
// rewrite edge bc, create edge af
replace_edge_triangle(ebc, t0, t2);
int eaf = eab;
replace_edge_vertex(eaf, b, f);
vertex_edges[b].Remove(eab);
vertex_edges[f].Add(eaf);
// create new edges fb and fc
int efb = add_edge(f, b, t2);
int efc = add_edge(f, c, t0, t2);
// update triangle edge-nbrs
replace_triangle_edge(t0, ebc, efc);
set_triangle_edges(t2, efb, ebc, efc);
// update vertex refcounts
vertices_refcount.increment(c);
vertices_refcount.increment(f, 2);
split.bIsBoundary = true;
split.vNew = f;
split.eNew = efb;
updateTimeStamp(true);
return(MeshResult.Ok);
}
else // interior triangle branch
// look up other triangle
{
int t1 = edges[eab_i + 3];
Index3i T1tv = GetTriangle(t1);
int[] T1tv_array = T1tv.array;
int d = IndexUtil.find_tri_other_vtx(a, b, T1tv_array);
// look up edges that we are going to need to update
// [TODO OPT] could use ordering to reduce # of compares here
Index3i T0te = GetTriEdges(t0);
int ebc = T0te[IndexUtil.find_edge_index_in_tri(b, c, T0tv_array)];
Index3i T1te = GetTriEdges(t1);
int edb = T1te[IndexUtil.find_edge_index_in_tri(d, b, T1tv_array)];
// rewrite existing triangles
replace_tri_vertex(t0, b, f);
replace_tri_vertex(t1, b, f);
// add two new triangles to close holes we just created
int t2 = add_triangle_only(f, b, c, InvalidID, InvalidID, InvalidID);
int t3 = add_triangle_only(f, d, b, InvalidID, InvalidID, InvalidID);
if (triangle_groups != null)
{
triangle_groups.insert(triangle_groups[t0], t2);
triangle_groups.insert(triangle_groups[t1], t3);
}
// update the edges we found above, to point to new triangles
replace_edge_triangle(ebc, t0, t2);
replace_edge_triangle(edb, t1, t3);
// edge eab became eaf
int eaf = eab; //Edge * eAF = eAB;
replace_edge_vertex(eaf, b, f);
// update a/b/f vertex-edges
vertex_edges[b].Remove(eab);
vertex_edges[f].Add(eaf);
// create new edges connected to f (also updates vertex-edges)
int efb = add_edge(f, b, t2, t3);
int efc = add_edge(f, c, t0, t2);
int edf = add_edge(d, f, t1, t3);
// update triangle edge-nbrs
replace_triangle_edge(t0, ebc, efc);
replace_triangle_edge(t1, edb, edf);
set_triangle_edges(t2, efb, ebc, efc);
set_triangle_edges(t3, edf, edb, efb);
// update vertex refcounts
vertices_refcount.increment(c);
vertices_refcount.increment(d);
vertices_refcount.increment(f, 4);
split.bIsBoundary = false;
split.vNew = f;
split.eNew = efb;
updateTimeStamp(true);
return(MeshResult.Ok);
}
}
