sqrt7 subdivision

sqrt7.cs

    KPlanktonMesh ma = mesh.ToKPlanktonMesh();
    double[] weightsA = new double[3]{4 / 7f,2 / 7f,1 / 7f};
    double[] weightsB = new double[3]{4 / 7f,1 / 7f,2 / 7f};
    for(int k = 0;k < level;k++)
    {
      KPlanktonMesh mb = new KPlanktonMesh();
      var hes = ma.Halfedges;
      for(int i = 0;i < hes.Count;i++)
      {
        var next = hes[hes[i].NextHalfedge];
        var nextnext = hes[next.NextHalfedge];
        Point3d[] pts = new Point3d[3]{
          ma.Vertices[hes[i].StartVertex].ToPoint3d(),
          ma.Vertices[next.StartVertex].ToPoint3d(),
          ma.Vertices[nextnext.StartVertex].ToPoint3d()};
        Point3d p = new Point3d();
        for(int j = 0;j < 3;j++) p += pts[j] * ((alternating && k % 2 == 0) ? weightsB[j] : weightsA[j]);
        mb.Vertices.Add(p);
      }
      for(int i = 0;i < ma.Vertices.Count;i++)
      {
        Point3d p = ma.Vertices[i].ToPoint3d();
        int[] neighbours = ma.Vertices.GetVertexNeighbours(i);
        int n = neighbours.Length;
        Point3d a = new Point3d();
        for(int j = 0;j < n;j++) a += ma.Vertices[neighbours[j]].ToPoint3d();
        double w = (16.0 - 4 * Math.Cos(2 * Math.PI / n)) / 49.0;
        int v = mb.Vertices.Add((1 - w) * p + w * a / n);
        int[] h = ma.Vertices.GetHalfedges(i);
        for(int j = 0;j < h.Length;j++) mb.Faces.AddFace(h[j], v, h[(j + 1) % h.Length]);
      }
      for(int i = 0;i < hes.Count;i++)
        mb.Faces.AddFace(i,
          (alternating && k % 2 == 0) ? ma.Halfedges[ma.Halfedges.GetPairHalfedge(i)].NextHalfedge : ma.Halfedges.GetPairHalfedge(i),
          ma.Halfedges[i].NextHalfedge);
      for(int i = 0;i < ma.Faces.Count;i++)
      {
        int[] h = ma.Faces.GetHalfedges(i);
        mb.Faces.AddFace(h[0], h[1], h[2]);
      }
      ma = mb;
    }
    A = ma.ToRhinoMesh();