/// <summary>
/// Adds a new vertex into the triangulation.
/// Splits a triangle intro three, conserving the three triangle edges.
/// </summary>
/// <remarks>
/// Vertex should lie within some triangle
/// Tip: (initialize triangulation with large bounding triangle)
/// </remarks>
/// <param name="m_vertex"></param>
public void AddVertex(Vector2 m_vertex)
{
var t = FindContainingTriangle(m_vertex);
if (t == null)
{
throw new GeomException("Vertex to be added is outside triangulation");
}
// remove old triangle
RemoveTriangle(t);
// create new edges
var e0x = new TriangleEdge(t.P0, m_vertex, null, null);
var ex0 = new TriangleEdge(m_vertex, t.P0, e0x, null);
e0x.Twin = ex0;
var e1x = new TriangleEdge(t.P1, m_vertex, null, null);
var ex1 = new TriangleEdge(m_vertex, t.P1, e1x, null);
e1x.Twin = ex1;
var e2x = new TriangleEdge(t.P2, m_vertex, null, null);
var ex2 = new TriangleEdge(m_vertex, t.P2, e2x, null);
e2x.Twin = ex2;
// create three new triangles
AddTriangle(new Triangle(t.E0, e1x, ex0));
AddTriangle(new Triangle(t.E1, e2x, ex1));
AddTriangle(new Triangle(t.E2, e0x, ex2));
}
/// <summary>
/// Finds edge that connects to the vertex and is not equal to given edge.
/// </summary>
/// <param name="a_edge"></param>
/// <param name="a_vertex"></param>
/// <returns></returns>
public TriangleEdge OtherEdge(TriangleEdge a_edge, Vector2 a_vertex)
{
if (!Edges.Contains(a_edge) || !Vertices.Contains(a_vertex))
{
throw new GeomException("Edge or vertex not contained in triangle");
}
return(Edges.Find(e => e != a_edge && e.IsEndpoint(a_vertex)));
}
/// <summary>
/// Finds the edge that is not equal to given two.
/// </summary>
/// <param name="a_edge0"></param>
/// <param name="a_edge1"></param>
/// <returns></returns>
public TriangleEdge OtherEdge(TriangleEdge a_edge0, TriangleEdge a_edge1)
{
if (!Edges.Contains(a_edge0) || !Edges.Contains(a_edge1))
{
throw new GeomException("One of the edges not contained in triangle");
}
return(Edges.Find(e => e != a_edge0 && e != a_edge1));
}
/// <summary>
/// Find the vertex that is not covered by the given triangle edge.
/// </summary>
/// <param name="a_edge"></param>
/// <returns></returns>
public Vector2?OtherVertex(TriangleEdge a_edge)
{
if (a_edge != E0 && a_edge != E1 && a_edge != E2)
{
throw new GeomException(string.Format("{0} not equal to any triangle edge of {1}", a_edge, this));
}
return(OtherVertex(a_edge.Point1, a_edge.Point2));
}
public Triangle(TriangleEdge a_edge0, TriangleEdge a_edge1, TriangleEdge a_edge2)
{
if (a_edge0.Point2 != a_edge1.Point1 || a_edge1.Point2 != a_edge2.Point1 || a_edge2.Point2 != a_edge0.Point1)
{
throw new GeomException("Invalid triangle edges given: " + a_edge0 + " " + a_edge1 + " " + a_edge2);
}
E0 = a_edge0;
E1 = a_edge1;
E2 = a_edge2;
// set the triangle pointer of the edges
a_edge0.T = a_edge1.T = a_edge2.T = this;
}
public TriangleEdge(Vector2 a_point1, Vector2 a_point2, TriangleEdge twin, Triangle t) : this(a_point1, a_point2)
{
Twin = twin;
T = t;
}