4xLinesOP

let sliderOne;

let x1 = 0;

let y1 = 0;

let x2 = 399;

let y2 = 399;

let x3 = 0;

let y3 = 399;

let x4 = 399;

let y4 = 0;

let speed1 = 9;

let speed2 = 15;

let speed3 = 3;

let speed4 = 24;

​

function setup() {

  createCanvas(400, 400);

  background(0);

  frameRate(15);

}

​

function draw() {

  stroke(255);

  strokeWeight(2);

  line(x1, 0, x1, y1);

  x1 += speed1;

  y1 += speed1;

​

  stroke(255);

  strokeWeight(2);

  line(x2, 400, x2, y2);

  x2 += speed2;

  y2 += speed2;

​

  stroke(255);

  strokeWeight(2);

  line(0, y3, x3, y3);

  x3 += speed3;

  y3 -= speed3;

​

  stroke(255);

  strokeWeight(2);

  line(x4, y4, 399, y4);

  x4 += speed4;

  y4 -= speed4;

​

  if (x1 >= width || x1 < 0) {

    speed1 *= -1;

    background(0);

  }

  if (x2 >= width || x2 < 0) {

    speed2 *= -1;

  }

  if (x3 >= width || x3 < 0) {

    speed3 *= -1;

    background(0);

  }

  if (x4 >= width || x4 < 0) {

    speed4 *= -1;

  }

}

​