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. 2021 May 19;21(10):3520. doi: 10.3390/s21103520
Algorithm 1 Determining if a point is inside a polygon.
  • Input: 

    x0,y0: sequence of previously visited locations;

  • Output: 

    Is point located in polygon

  • 1:

    int crossings = 0;

  • 2:

    for (int i = 0;i < N ;i++) do

  • 3:

     double slope = (y[i + 1] − y[i]) / (x[i + 1] − x[i]);

  • 4:

     bool cond1 = (x[i] ≤ x0) && (x0 < x[i + 1]);

  • 5:

     bool cond2 = (x[i + 1] ≤ x0) && (x0 < x[i]);

  • 6:

     if ((cond1 || cond2) && above) then

  • 7:

      crossings ++;

  • 8:

     end if

  • 9:

    end for

  • 10:

    if crossings % 2 == 0 then

  • 11:

     return false;

  • 12:

    else

  • 13:

     return true;

  • 14:

    end if