//From triangle where each triangle has one vertex to half edge
public static List <HalfEdge> TransformFromTriangleToHalfEdge(List <Triangle> triangles)
{
//Make sure the triangles have the same orientation
MeshOperations.OrientTrianglesClockwise(triangles);
//First create a list with all possible half-edges
List <HalfEdge> halfEdges = new List <HalfEdge>(triangles.Count * 3);
for (int i = 0; i < triangles.Count; i++)
{
Triangle t = triangles[i];
HalfEdge he1 = new HalfEdge(t.v1);
HalfEdge he2 = new HalfEdge(t.v2);
HalfEdge he3 = new HalfEdge(t.v3);
he1.nextEdge = he2;
he2.nextEdge = he3;
he3.nextEdge = he1;
he1.prevEdge = he3;
he2.prevEdge = he1;
he3.prevEdge = he2;
//The vertex needs to know of an edge going from it
he1.v.halfEdge = he2;
he2.v.halfEdge = he3;
he3.v.halfEdge = he1;
//The face the half-edge is connected to
t.halfEdge = he1;
he1.t = t;
he2.t = t;
he3.t = t;
//Add the half-edges to the list
halfEdges.Add(he1);
halfEdges.Add(he2);
halfEdges.Add(he3);
}
//Find the half-edges going in the opposite direction
for (int i = 0; i < halfEdges.Count; i++)
{
HalfEdge he = halfEdges[i];
Vertex goingToVertex = he.v;
Vertex goingFromVertex = he.prevEdge.v;
for (int j = 0; j < halfEdges.Count; j++)
{
//Dont compare with itself
if (i == j)
{
continue;
}
HalfEdge heOpposite = halfEdges[j];
//Is this edge going between the vertices in the opposite direction
if (goingFromVertex.position == heOpposite.v.position && goingToVertex.position == heOpposite.prevEdge.v.position)
{
he.oppositeEdge = heOpposite;
break;
}
}
}
return(halfEdges);
}
public Triangle(HalfEdge halfEdge)
{
this.halfEdge = halfEdge;
}