TelpoPushFence/TelpoPush.Fence.Worker/Models/Fence/Algorithms/RayCastingAlgorithm.cs

namespace TelpoPush.Fence.Worker.Models.Fence
{
    public static class RayCastingAlgorithm
    {
        public static bool IsWithin(GpsFencePoint pt, IList<GpsFencePoint> polygon, bool noneZeroMode)
        {
            int ptNum = polygon.Count();
            if (ptNum < 3)
            {
                return false;
            }
            int j = ptNum - 1;
            bool oddNodes = false;
            int zeroState = 0;
            for (int k = 0; k < ptNum; k++)
            {
                var ptK = polygon[k];
                var ptJ = polygon[j];
                if (ptK.Latitude > pt.Latitude != ptJ.Latitude > pt.Latitude && pt.Longitude < (ptJ.Longitude - ptK.Longitude) * (pt.Latitude - ptK.Latitude) / (ptJ.Latitude - ptK.Latitude) + ptK.Longitude)
                {
                    oddNodes = !oddNodes;
                    if (ptK.Latitude > ptJ.Latitude)
                    {
                        zeroState++;
                    }
                    else
                    {
                        zeroState--;
                    }
                }
                j = k;
            }
            return noneZeroMode ? zeroState != 0 : oddNodes;
        }
    }
}