Find if point lays on line segment

Question

I have line segment defined by two points A(x1,y1,z1) and B(x2,y2,z2) and point p(x,y,z). How can I check if the point lays on the line segment?

Answer 1

Or let the dotnet do the heavy lifting for you if using visual studio use a GraphicsPath

this will also allow you to add tolerances for if just clicked outside the line.

using (Drawing2D.GraphicsPath gp = new Drawing2D.GraphicsPath())
{
    gp.AddLine(new Point(x1, y1), new Point(x2, y2));

    // Make the line as wide as needed (make this larger to allow clicking slightly outside the line) 
    using (Pen objPen = new Pen(Color.Black, 6))
    {
        gp.Widen(objPen);
    }

    if (gp.IsVisible(Mouse.x, Mouse.y))
    {
        // The line was clicked
    }
}