/// <summary>
/// Find the next edge clockwise with the same destination. [dprev(abc) -> cb*]
/// </summary>
public void Dprev(ref Otri ot)
{
//Lnext(ref ot);
ot.tri = tri;
ot.orient = plus1Mod3[orient];
//ot.SymSelf();
int tmp = ot.orient;
ot.orient = ot.tri.neighbors[tmp].orient;
ot.tri = ot.tri.neighbors[tmp].tri;
}
/// <summary>
/// Find the previous edge (clockwise) of the adjacent triangle. [rprev(abc) -> b**]
/// </summary>
public void Rprev(ref Otri ot)
{
//Sym(ref ot);
ot.tri = tri.neighbors[orient].tri;
ot.orient = tri.neighbors[orient].orient;
//ot.LprevSelf();
ot.orient = minus1Mod3[ot.orient];
//ot.SymSelf();
int tmp = ot.orient;
ot.orient = ot.tri.neighbors[tmp].orient;
ot.tri = ot.tri.neighbors[tmp].tri;
}
/// <summary>
/// Finds a triangle abutting a subsegment.
/// </summary>
internal void Pivot(ref Otri ot)
{
ot = seg.triangles[orient];
}
// The following primitives are all described by Guibas and Stolfi.
// However, Guibas and Stolfi use an edge-based data structure,
// whereas I use a triangle-based data structure.
//
// lnext: finds the next edge (counterclockwise) of a triangle.
//
// onext: spins counterclockwise around a vertex; that is, it finds
// the next edge with the same origin in the counterclockwise direction. This
// edge is part of a different triangle.
//
// oprev: spins clockwise around a vertex; that is, it finds the
// next edge with the same origin in the clockwise direction. This edge is
// part of a different triangle.
//
// dnext: spins counterclockwise around a vertex; that is, it finds
// the next edge with the same destination in the counterclockwise direction.
// This edge is part of a different triangle.
//
// dprev: spins clockwise around a vertex; that is, it finds the
// next edge with the same destination in the clockwise direction. This edge
// is part of a different triangle.
//
// rnext: moves one edge counterclockwise about the adjacent
// triangle. (It's best understood by reading Guibas and Stolfi. It
// involves changing triangles twice.)
//
// rprev: moves one edge clockwise about the adjacent triangle.
// (It's best understood by reading Guibas and Stolfi. It involves
// changing triangles twice.)
/// <summary>
/// Find the abutting triangle; same edge. [sym(abc) -> ba*]
/// </summary>
/// Note that the edge direction is necessarily reversed, because the handle specified
/// by an oriented triangle is directed counterclockwise around the triangle.
/// </remarks>
public void Sym(ref Otri ot)
{
ot.tri = tri.neighbors[orient].tri;
ot.orient = tri.neighbors[orient].orient;
}
/// <summary>
/// Test for equality of oriented triangles.
/// </summary>
public bool Equals(Otri ot)
{
return((tri == ot.tri) && (orient == ot.orient));
}
/// <summary>
/// Copy an oriented triangle.
/// </summary>
public void Copy(ref Otri ot)
{
ot.tri = tri;
ot.orient = orient;
}
/// <summary>
/// Find the previous edge (clockwise) of a triangle. [lprev(abc) -> cab]
/// </summary>
public void Lprev(ref Otri ot)
{
ot.tri = tri;
ot.orient = minus1Mod3[orient];
}
/// <summary>
/// Find the next edge (counterclockwise) of a triangle. [lnext(abc) -> bca]
/// </summary>
public void Lnext(ref Otri ot)
{
ot.tri = tri;
ot.orient = plus1Mod3[orient];
}