public static List <int[]> ComputeNonConcaveSubPolygons(
this V3d[] vertexArray, int polyCount,
V3d[] normalArray, int[] firstIndices, int[] vertexIndices,
List <int> faceBackMap,
double absoluteEpsilon)
{
var polyList = new List <int[]>();
var eps2 = absoluteEpsilon * absoluteEpsilon;
for (int fvi = 0, fi = 0; fi < polyCount; fi++)
{
int fve = firstIndices[fi + 1], fvc = fve - fvi;
var n = normalArray[fi];
var l2 = n.LengthSquared;
if (l2 < eps2)
{
polyList.Add(new int[fvc].SetByIndex(i => vertexIndices[fvi + i]));
if (faceBackMap != null)
{
faceBackMap.Add(fi);
}
fvi = fve;
continue;
}
M44d local2global, global2local;
M44d.NormalFrame(V3d.Zero, n, out local2global, out global2local);
var polygon = new Polygon2d(fvc,
i => global2local.TransformPos(vertexArray[vertexIndices[fvi + i]]).XY);
var subPolyList = polygon.ComputeNonConcaveSubPolygons(absoluteEpsilon);
foreach (var poly in subPolyList)
{
polyList.Add(poly.Map(i => fvi + i));
}
if (faceBackMap != null)
{
for (int i = 0; i < subPolyList.Count; i++)
{
faceBackMap.Add(fi);
}
}
fvi = fve;
}
return(polyList);
}
