public static List<Point> Scan(List<Point> _points)
{
if (_points.Count() < 4) return _points; //Only 3 or less points, so they all must be on the hull
Point start = GetLowestPoint(_points); //Get the lowest point in the list
List<Point> points = RemovePoint(_points, start); //remove the lowest point from the list
List<Point> hull = new List<Point>();
PointComparator pc = new PointComparator(start); //Create a new comparator for the list of points
points.Sort(pc.Compare); //Sort points based on the angle from the start point
//Add first 3 points
hull.Add(start);
for (int i = 0; i < 2; i++)
{
hull.Add(points[0]);
points.RemoveAt(0);
}
//Find Points that are on the hull
while(points.Count()>0)
{
Point p = points[0];
Point a = hull[hull.Count() - 2]; //Get the second to last point on the hull
Point b = hull[hull.Count() - 1]; //Get the last point on the hull
if(PointComparator.isLeftIncl(a,b,p))
{
hull.Add(p); //Point is on the hull, so add it to the hull
points.RemoveAt(0); //Remove the point of the list of points we are processing
}
else hull.RemoveAt(hull.Count() - 1);
}
return hull;
}
public void comparatorTest()
{
List<Point> points = new List<Point>();
Point start = new Point(1,1,1);
points.Add(new Point(-1, 3, 1));
points.Add(new Point(3,3,1));
points.Add(new Point(2,2,1));
points.Add(new Point(2,4,1));
PointComparator pc = new PointComparator(start);
points.Sort(pc.Compare);
Assert.AreEqual(new Point(2, 2, 1), points[0]);
Assert.AreEqual(new Point(3, 3, 1), points[1]);
Assert.AreEqual(new Point(2, 4, 1), points[2]);
Assert.AreEqual(new Point(-1,3,1), points[3]);
}
