/// <summary>
/// Removes ghost triangles.
/// </summary>
/// <param name="startghost"></param>
/// <returns>Number of vertices on the hull.</returns>
int RemoveGhosts(ref Otri startghost)
{
Otri searchedge = default(Otri);
Otri dissolveedge = default(Otri);
Otri deadtriangle = default(Otri);
Vertex markorg;
int hullsize;
bool noPoly = !_TriangleNetMesh.behavior.Poly;
// Find an edge on the convex hull to start point location from.
startghost.Lprev(ref searchedge);
searchedge.Sym();
_TriangleNetMesh.dummytri.neighbors[0] = searchedge;
// Remove the bounding box and count the convex hull edges.
startghost.Copy(ref dissolveedge);
hullsize = 0;
do
{
hullsize++;
dissolveedge.Lnext(ref deadtriangle);
dissolveedge.Lprev();
dissolveedge.Sym();
// If no PSLG is involved, set the boundary markers of all the vertices
// on the convex hull. If a PSLG is used, this step is done later.
if (noPoly)
{
// Watch out for the case where all the input vertices are collinear.
if (dissolveedge.tri.id != TriangleNetMesh.DUMMY)
{
markorg = dissolveedge.Org();
if (markorg.label == 0)
{
markorg.label = 1;
}
}
}
// Remove a bounding triangle from a convex hull triangle.
dissolveedge.Dissolve(_TriangleNetMesh.dummytri);
// Find the next bounding triangle.
deadtriangle.Sym(ref dissolveedge);
// Delete the bounding triangle.
_TriangleNetMesh.TriangleDealloc(deadtriangle.tri);
} while (!dissolveedge.Equals(startghost));
return(hullsize);
}
/// <summary>
/// Remove the "infinite" bounding triangle, setting boundary markers as appropriate.
/// </summary>
/// <returns>Returns the number of edges on the convex hull of the triangulation.</returns>
/// <remarks>
/// The triangular bounding box has three boundary triangles (one for each
/// side of the bounding box), and a bunch of triangles fanning out from
/// the three bounding box vertices (one triangle for each edge of the
/// convex hull of the inner mesh). This routine removes these triangles.
/// </remarks>
int RemoveBox()
{
Otri deadtriangle = default(Otri);
Otri searchedge = default(Otri);
Otri checkedge = default(Otri);
Otri nextedge = default(Otri), finaledge = default(Otri), dissolveedge = default(Otri);
Vertex markorg;
int hullsize;
bool noPoly = !_TriangleNetMesh.behavior.Poly;
// Find a boundary triangle.
nextedge.tri = _TriangleNetMesh.dummytri;
nextedge.orient = 0;
nextedge.Sym();
// Mark a place to stop.
nextedge.Lprev(ref finaledge);
nextedge.Lnext();
nextedge.Sym();
// Find a triangle (on the boundary of the vertex set) that isn't
// a bounding box triangle.
nextedge.Lprev(ref searchedge);
searchedge.Sym();
// Check whether nextedge is another boundary triangle
// adjacent to the first one.
nextedge.Lnext(ref checkedge);
checkedge.Sym();
if (checkedge.tri.id == TriangleNetMesh.DUMMY)
{
// Go on to the next triangle. There are only three boundary
// triangles, and this next triangle cannot be the third one,
// so it's safe to stop here.
searchedge.Lprev();
searchedge.Sym();
}
// Find a new boundary edge to search from, as the current search
// edge lies on a bounding box triangle and will be deleted.
_TriangleNetMesh.dummytri.neighbors[0] = searchedge;
hullsize = -2;
while (!nextedge.Equals(finaledge))
{
hullsize++;
nextedge.Lprev(ref dissolveedge);
dissolveedge.Sym();
// If not using a PSLG, the vertices should be marked now.
// (If using a PSLG, markhull() will do the job.)
if (noPoly)
{
// Be careful! One must check for the case where all the input
// vertices are collinear, and thus all the triangles are part of
// the bounding box. Otherwise, the setvertexmark() call below
// will cause a bad pointer reference.
if (dissolveedge.tri.id != TriangleNetMesh.DUMMY)
{
markorg = dissolveedge.Org();
if (markorg.label == 0)
{
markorg.label = 1;
}
}
}
// Disconnect the bounding box triangle from the mesh triangle.
dissolveedge.Dissolve(_TriangleNetMesh.dummytri);
nextedge.Lnext(ref deadtriangle);
deadtriangle.Sym(ref nextedge);
// Get rid of the bounding box triangle.
_TriangleNetMesh.TriangleDealloc(deadtriangle.tri);
// Do we need to turn the corner?
if (nextedge.tri.id == TriangleNetMesh.DUMMY)
{
// Turn the corner.
dissolveedge.Copy(ref nextedge);
}
}
_TriangleNetMesh.TriangleDealloc(finaledge.tri);
return(hullsize);
}
