Question

I have a piece of code that checks if the given 3 coordinates are linear to one another (if so, return true). But is there a way to make the code give or take a few pixels/plots?

private boolean collinear(double x1, double y1, double x2, double y2, double x3, double y3) {
    return (y1 - y2) * (x1 - x3) == (y1 - y3) * (x1 - x2);
}

You see, the coordinates have to be exactly inline for it to register as linear. How will I be able to make it look within a ‘range’ of some kind, for it to check within a value, and then to then set the coordinates with the new value?

—- Added —-

I’m trying to see if the 3 points make a linear line, but I want it to check within a threshold (as some points maybe off by a little). Once the Java has found that in fact the points are linear (give or take), I want it to then replace the x1, x2, x3, y1 ect … with what the value would have been that Java checked against.

Answer 1

Using the Hesse Normal Form you can calculate the perpendicular distance from a point to a line. So when the distance is smaller than a treshhold, they are sufficiently near.

Such code is called distanceFromLine()
Java has that built in

   Line2D line = new Line2D.Double(x0, y0, x1, y1);

    double distance = line.ptLineDist(px, py);

    if (Math.abs(distance) < threshold) {
              // is Near line
    }