/// <summary>
///
/// </summary>
/// <param name="points"></param>
/// <param name="threshold">Must be between 0 and 1</param>
/// <returns></returns>
public static IPoint[] SimplifyByAngle(IPoint[] points, double threshold)
{
if (points == null || points.Length == 0)
{
return(null);
}
else if (points.Length == 2)
{
return(points);
}
List <Tuple <int, double> > angles = new List <Tuple <int, double> >();
for (int i = 0; i < points.Length - 2; i++)
{
var angle = SpatialUtility.CalculateSemiCosineOfAngle(points[i], points[i + 1], points[i + 2]);
angles.Add(new Tuple <int, double>(i + 1, angle));
}
//When i.Item2 ~ 1 it means points are on a line
var filter1 = angles.Where(i => i.Item2 < threshold).Select(i => i.Item1).ToList();
filter1.Insert(0, 0);
filter1.Add(points.Length - 1);
var output1 = filter1.Select(i => points[i]).ToArray();
return(output1);
}
/// <summary>
/// Additive Angle + Area Check
/// </summary>
/// <param name="points"></param>
/// <param name="anglethreshold">Must be between 0 and 1</param>
/// <returns></returns>
public static IPoint[] AdditiveSimplifyByAngleArea(IPoint[] points, double angleThreshold, double areaThreshold)
{
if (points == null || points.Length == 0)
{
return(null);
}
else if (points.Length == 2)
{
return(points);
}
List <int> filtered = new List <int>();
filtered.Add(0);
int firstIndex = 0, secondIndex = 1, thirdIndex = 2;
double tempArea = 0;
while (thirdIndex < points.Length)
{
var angle = SpatialUtility.CalculateSemiCosineOfAngle(points[firstIndex], points[secondIndex], points[thirdIndex]);
var area = SpatialUtility.CalculateTriangleArea(points[firstIndex], points[secondIndex], points[thirdIndex]);
tempArea += area;
//if (Math.Abs(angle) < threshold)
//{
if ((angle < 0 || angle < angleThreshold) || tempArea > areaThreshold)
{
filtered.Add(secondIndex);
firstIndex = secondIndex;
tempArea = 0;
}
secondIndex = thirdIndex;
thirdIndex = thirdIndex + 1;
}
if (filtered.Count == 1)
{
filtered.Add(points.Count() / 2);
}
filtered.Add(points.Length - 1);
var output1 = filtered.Select(i => points[i]).ToArray();
return(output1);
}
