public static List <Mesh> MarchingCubes(this Mesh3D mesh3d, List <double> vertexValues, List <double> isoValues)
{
if (mesh3d?.Vertices == null || vertexValues == null || mesh3d.Vertices.Count != vertexValues.Count)
{
Reflection.Compute.RecordError("Number of vertexValues must match the number of vertices in the mesh.");
return(new List <Mesh>());
}
if (isoValues == null)
{
return(new List <Mesh>());
}
// add empty lists
List <List <Point> > vertices = new List <List <Point> >();
List <List <Face> > faces = new List <List <Face> >();
for (int i = 0; i < isoValues.Count; i++)
{
vertices.Add(new List <Point>());
faces.Add(new List <Face>());
}
// SubMesh works on regular meshes, and since we're looking at it one cell at a time, the extra information in the mesh3d is not needed
Mesh meshVersion = mesh3d.ToMesh();
// Look at every cell
foreach (List <Face> cell in mesh3d.Cells())
{
// Create a mesh from the cell
var meshAndValues = SubMesh(meshVersion, cell, vertexValues);
// Find the iso lines for the boundary of the cell
List <List <Polyline> > pLines = MarchingSquares(meshAndValues.Item1, meshAndValues.Item2, isoValues).Select(x => x.Join()).ToList();
// Create faces from the polyline
// Note that each vertex may be added twice here from neighboring cells
for (int j = 0; j < isoValues.Count; j++)
{
foreach (Polyline polyline in pLines[j])
{
vertices[j].AddRange(polyline.ControlPoints.Skip(1));
int nPts = vertices[j].Count;
int first = polyline.ControlPoints.Count - 1;
// A rough triangulation of the imagined face covering the polyline, (assumes convex polyline)
for (int i = 1; i < first - 1; i++)
{
faces[j].Add(new Face()
{
A = nPts - first,
B = nPts - (i + 1),
C = nPts - i,
});
}
}
}
}
return(vertices.Zip(faces, (v, f) => new Mesh()
{
Vertices = v,
Faces = f,
}).ToList());
}
