Draw polygon from unordered points

Question

So, I know that there are similar questions and I searched a lot before typing my code and asking this question.

In my case, the user clicks on a place on the screen to add a point. When the user finishes adding points, makes a right click to say that the points are ok and draw the polygon.

A the poins are irregularly placed, I must calculate the center point and the angle of each point to order the point list.

And then, when I move a point, I recalculate the angles with new positions and redraw the polygon.

It works but, when I move a point beyond two others beyond them, sometimes it doesn't draw the plygon. I couldn't find what is wrong.

here is my code and two images to explain the problem :

public class CustomPoint3D
{
    public double X { get; set; }
    public double Y { get; set; }
    public double Z { get; set; }
    public int Angle { get; set; }
    public CustomPoint3D()
    {

    }

    public CustomPoint3D(double x, double y, double z)
    {
        this.X = x;
        this.Y = y;
        this.Z = z;
    }
}



    private void AddZoneSurface(List<CustomPoint3D> customPoints, string guid)
    {

        //Calculates angles and orders / sorts the list of points
        List<Point2D> points = From3DTo2D(customPoints);

        //Draws a polygon in Eyeshot but it can be any tool to create a polygon.
        var polygon = devDept.Eyeshot.Entities.Region.CreatePolygon(points.ToArray());


        polygon.ColorMethod = colorMethodType.byEntity;
        polygon.EntityData = "tool-surface-" + guid;
        polygon.Color = System.Drawing.Color.FromArgb(80, 0, 0, 0);
        sceneLeft.Entities.Add(polygon);

       
        sceneLeft.Invalidate();
    }

    private List<Point2D> From3DTo2D(List<CustomPoint3D> points)
    {
        List<Point2D> retVal = new List<Point2D>();
        var minX = points.Min(ro => ro.X);
        var maxX = points.Max(ro => ro.X);
        var minY = points.Min(ro => ro.Y);
        var maxY = points.Max(ro => ro.Y);

        var center = new CustomPoint3D()
        {
            X = minX + (maxX - minX) / 2,
            Y = minY + (maxY - minY) / 2
        };

        // precalculate the angles of each point to avoid multiple calculations on sort
        for (var i = 0; i < points.Count; i++)
        {
            points[i].Angle = (int)(Math.Acos((points[i].X - center.X) / lineDistance(center, points[i])));

            if (points[i].Y > center.Y)
            {
                points[i].Angle = (int)(Math.PI + Math.PI - points[i].Angle);
            }
        }
        //points.Sort((a, b) => a.Angle - b.Angle);
        points = points.OrderBy(ro => ro.Angle).ToList();
        foreach (var item in points)
        {
            retVal.Add(new Point2D() { X = item.X, Y = item.Y });
        }
        return retVal;
    }


    double lineDistance(CustomPoint3D point1, CustomPoint3D point2)
    {
        double xs = 0;
        double ys = 0;

        xs = point2.X - point1.X;
        xs = xs * xs;

        ys = point2.Y - point1.Y;
        ys = ys * ys;

        return Math.Sqrt(xs + ys);
    }

On the first images, I move the point from its initial position to the indicated position, it doesn't draw the polygon.

Answer 1

So if someone needs a sample which works, I found the problem. I should have declared the angle property of th CustomPoint3D object like this As the property was integer, an angle 0,3 or 0,99 was giving 0 as angle.

 public class CustomPoint3D
 {
  public double X { get; set; }
  public double Y { get; set; }
  public double Z { get; set; }
  public double Angle { get; set; }
  public CustomPoint3D()
 {

}

  public CustomPoint3D(double x, double y, double z)
  {
    this.X = x;
    this.Y = y;
    this.Z = z;
  }
}

and calculate this values as double

     private List<Point2D> From3DTo2D(List<CustomPoint3D> points)
{
    List<Point2D> retVal = new List<Point2D>();
    var minX = points.Min(ro => ro.X);
    var maxX = points.Max(ro => ro.X);
    var minY = points.Min(ro => ro.Y);
    var maxY = points.Max(ro => ro.Y);

    var center = new CustomPoint3D()
    {
        X = minX + (maxX - minX) / 2,
        Y = minY + (maxY - minY) / 2
    };

    // precalculate the angles of each point to avoid multiple calculations on sort
    for (var i = 0; i < points.Count; i++)
    {
        points[i].Angle = Math.Acos((points[i].X - center.X) / lineDistance(center, points[i]));

        if (points[i].Y > center.Y)
        {
            points[i].Angle = Math.PI + Math.PI - points[i].Angle;
        }
    }
    //points.Sort((a, b) => a.Angle - b.Angle);
    points = points.OrderBy(ro => ro.Angle).ToList();
    foreach (var item in points)
    {
        retVal.Add(new Point2D() { X = item.X, Y = item.Y });
    }
    return retVal;
}

And