duck

    public static float SignedDistanceToLine2D( Vector2 point, Vector2 lineStart, Vector2 lineDirection )
    {
        Vector2 v = lineDirection;
        Vector2 w = point - lineStart;
        float c1 = Vector2.Dot(w,v);
        float c2 = Vector2.Dot(v,v);
        float b = c1 / c2;
        Vector2 pointOnLine = lineStart + b * v;

        Vector2 diff = (point-pointOnLine);
        int side = Vector2.Dot(diff,lineDirection) > 0 ? 1 : -1;


        return diff.magnitude * side;
    }