public static List<Polygon> RemoveOverlap(Polygon polygon1, List<Polygon> polygons)
{
foreach (var polygon in polygons)
{
if (!polygon1.IsCoplanarTo(polygon))
{
return null;
}
}
var normal = polygon1.NormalDirection;
//For clipper, everything must be converted to 2d, so any references to rotation are dealing with that
var rotation = GetRotation(normal);
var rotated1 = polygon1.Vertices.Shift(rotation);
var rotatedPolygons = new List<List<Point>>();
foreach (var polygon in polygons)
{
rotatedPolygons.Add(polygon.Vertices.Shift(rotation));
}
var overlapped = Remove_Overlap_In_XY_Plane(rotated1, rotatedPolygons);
if (overlapped.IsNull())
{
return null;
}
for (int i = 0; i < overlapped.Count; i++)
{
overlapped[i] = RemovePointsTooCloseToEachOther(overlapped[i]);
}
var depth = rotated1[0].Z;
var shiftBack = Shift.ComposeLeftToRight(depth * Direction.Out, rotation.Inverse());
var finalPolygons = new List<Polygon>();
//for some reason, Clipper will sometimes return very thin areas that we consider invalid and overlapping
//this function loops over all points in each polygon, and if the angle between any two
//segments is greater than 179 degrees, it gets rid of the intermediary point
for (int i = 0; i < overlapped.Count; i++)
{
var pointList = overlapped[i].Shift(shiftBack);
for (int j = 0; j < overlapped[i].Count; j++)
{
var index1 = j;
var index2 = j + 1;
var index3 = j + 2;
if (j == overlapped[i].Count - 1)
{
index2 = 0;
index3 = 1;
}
if (j == overlapped[i].Count - 2)
{
index3 = 0;
}
var seg1 = new LineSegment(pointList[index1], pointList[index2]);
var seg2 = new LineSegment(pointList[index2], pointList[index3]);
var angleBetween = seg1.AngleBetween(seg2);
if (Math.Abs(angleBetween.InDegrees.Value) >= 179)
{
overlapped[i].RemoveAt(index2);
}
}
}
//In rare cases, Clipper will return a polygon with no points, this removes those
for (int i = 0; i < overlapped.Count; i++)
{
if (overlapped[i].Count == 0)
{
overlapped.RemoveAt(i);
}
}
foreach (var polygonPointList in overlapped)
{
finalPolygons.Add(new Polygon(polygonPointList.Shift(shiftBack)));
}
return finalPolygons;
}
