private static HashSet <CommonEdge> GetEdgesDistinct(PolyMesh m, Dictionary <int, int> lookup, out List <CommonEdge> duplicates)
{
int[] tris = m.GetTriangles();
int count = tris.Length;
HashSet <CommonEdge> edges = new HashSet <CommonEdge>();
duplicates = new List <CommonEdge>();
for (int i = 0; i < count; i += 3)
{
CommonEdge a = new CommonEdge(tris[i + 0], tris[i + 1], lookup[tris[i + 0]], lookup[tris[i + 1]]);
CommonEdge b = new CommonEdge(tris[i + 1], tris[i + 2], lookup[tris[i + 1]], lookup[tris[i + 2]]);
CommonEdge c = new CommonEdge(tris[i + 2], tris[i + 0], lookup[tris[i + 2]], lookup[tris[i + 0]]);
if (!edges.Add(a))
{
duplicates.Add(a);
}
if (!edges.Add(b))
{
duplicates.Add(b);
}
if (!edges.Add(c))
{
duplicates.Add(c);
}
}
return(edges);
}
/// <summary>
/// Returns all vertex indices that are on an open edge.
/// </summary>
/// <param name="mesh"></param>
/// <returns></returns>
internal static HashSet <int> GetNonManifoldIndices(PolyMesh mesh)
{
if (mesh == null)
{
return(null);
}
List <CommonEdge> duplicates;
HashSet <CommonEdge> edges = GetEdgesDistinct(mesh, out duplicates);
edges.ExceptWith(duplicates);
HashSet <int> hash = CommonEdge.ToHashSet(edges);
return(hash);
}
