使用Reactor选择匹配键的事件(Select events matching a key using Reactor)

 使用Hesse Normal Form可以计算从点到线的垂直距离。 因此，当距离小于一个阈值时，它们足够接近。 
 
 这样的代码叫做distanceFromLine （），内置了Java 
 
   Line2D line = new Line2D.Double(x0, y0, x1, y1);

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

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

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
    }