private static LineEquationNumbers GetLineEquationNumbers(Line line)
{
LineEquationNumbers ln = new LineEquationNumbers();
ln.k = (line.Y2 - line.Y1) / (line.X2 - line.X1);
ln.b = line.Y1 - ln.k * line.X1;
return ln;
}
private static Point GetIntersectionOfTwoLines(LineEquationNumbers len1, LineEquationNumbers len2)
{
Point p = new Point();
if (len1.k == len2.k)
{
return p;
}
p.X = (len2.b - len1.b) / (len1.k - len2.k);
p.Y = len1.k * p.X + len1.b;
return p;
}
public static Point GetIntersectionOfLineAndPerpendicularFromPoint(Line line, Point point)
{
LineEquationNumbers ln1 = GetLineEquationNumbers(line);
LineEquationNumbers ln2 = new LineEquationNumbers();
//Find orthogonal line
//y = (-1/k1)*x + y0 + (1/k1)*x0
ln2.k = -1 / ln1.k;
ln2.b = point.Y + (1 / ln1.k) * point.X;
//Find intersectionof 2 lines
Point result = new Point();
result.X = (ln2.b - ln1.b) / (ln1.k - ln2.k);
result.Y = ln1.k * result.X + ln1.b;
return result;
}
public static LineEquationNumbers GetPerpendicularLine(Line line)
{
LineEquationNumbers ln1 = GetLineEquationNumbers(line);
LineEquationNumbers ln2 = new LineEquationNumbers();
//Find orthogonal line
//y = (-1/k1)*x + y0 + (1/k1)*x0
ln2.k = -1 / ln1.k;
ln2.b = 0;
return ln2;
}
public static List<Point> GetIntersectionOf(LineEquationNumbers len, Polygon polygon)
{
List<Point> list = new List<Point>();
for (int index = 0; index < polygon.Points.Count; index++)
{
int index2 = (index + 1) % polygon.Points.Count;
Line line1 = new Line();
line1.X1 = polygon.Points[index].X;
line1.X2 = polygon.Points[index2].X;
line1.Y1 = polygon.Points[index].Y;
line1.Y2 = polygon.Points[index2].Y;
LineEquationNumbers len1 = GetLineEquationNumbers(line1);
Point p = GetIntersectionOfTwoLines(len, len1);
if (p.X >= Math.Min(line1.X1, line1.X2) &&
p.X <= Math.Max(line1.X1, line1.X2) &&
p.Y >= Math.Min(line1.Y1, line1.Y2) &&
p.Y <= Math.Max(line1.Y1, line1.Y2))
{
list.Add(p);
}
}
return list;
}