source: branches/HeuristicLab.Problems.GrammaticalOptimization/DynamicDataDisplay/Charts/Filters/InclinationFilter.cs @ 12503

using System;
using System.Collections.Generic;
using System.Windows;
using Microsoft.Research.DynamicDataDisplay.Charts.Filters;

namespace Microsoft.Research.DynamicDataDisplay.Filters
{
  [Obsolete("Works incorrectly", true)]
  public sealed class InclinationFilter : PointsFilterBase
  {
    private double criticalAngle = 179;
    public double CriticalAngle
    {
      get { return criticalAngle; }
      set
      {
        if (criticalAngle != value)
        {
          criticalAngle = value;
          RaiseChanged();
        }
      }
    }

    #region IPointFilter Members

    public override List<Point> Filter(List<Point> points)
    {
      if (points.Count == 0)
        return points;

      List<Point> res = new List<Point> { points[0] };

      int i = 1;
      while (i < points.Count)
      {
        bool added = false;
        int j = i;
        while (!added && (j < points.Count - 1))
        {
          Point x1 = res[res.Count - 1];
          Point x2 = points[j];
          Point x3 = points[j + 1];

          double a = (x1 - x2).Length;
          double b = (x2 - x3).Length;
          double c = (x1 - x3).Length;

          double angle13 = Math.Acos((a * a + b * b - c * c) / (2 * a * b));
          double degrees = 180 / Math.PI * angle13;
          if (degrees < criticalAngle)
          {
            res.Add(x2);
            added = true;
            i = j + 1;
          }
          else
          {
            j++;
          }
        }
        // reached the end of resultPoints
        if (!added)
        {
          res.Add(points.GetLast());
          break;
        }
      }
      return res;
    }

    #endregion
  }
}