let y = [3];

let pos_x, pos_y;

let trigger;

​

function setup() {

  createCanvas(400, 400);

  x[0] = int(random(width));

  y[0] = int(random(height));

  x[1] = int(random(width));

  y[1] = int(random(height));

}

​

function draw() {

  background(0);

  stroke(255);

line(x[0], y[0], x[1], y[1]);

  x[2] = mouseX;

  y[2] = mouseY;

stroke(150, 0, 0);

line(x[0], y[0], x[2], y[2]);

stroke(0, 150, 0);

line(x[2], y[2], x[1], y[1]);

let A = (x[2] - x[1]) / (x[0] - x[1]);

let B = (y[2] - y[1]) / (y[0] - y[1]);

  if (abs(A - B) <= 0.1) {

    if (x[0] < x[1]) {

      if ((x[2] > x[0]) && (x[2] < x[1])) {

       trigger = 1; 

        }

     }

    else {

       if ((x[2] < x[0]) && (x[2] > x[1])) {

       trigger = 1; 

        }

    }

  }

   else {

      trigger = 0;

   }

​

 print(trigger, abs(A - B));

​

}