function setup() {

  createCanvas(560, 492);

  angleMode(DEGREES);

  rectMode(CENTER);

}

​

function draw() {

  background(20, 30);

  stroke(255);

  strokeWeight(1)

    angleUD = map(millis(), 0, 2000, 0, 180);

  angleLR = map(millis(), 0, 2000, 90, 270);

  line(mouseX, height/2, width/2, constrain(height * sin(angleUD), 0, height));

  line(mouseX, height/2, width/2, constrain(height * sin(angleUD), 0, height));

  line(width/2, mouseY, constrain(width * cos(angleLR), 0, width), height/2);

  line(width/2, mouseY, constrain(width * cos(angleLR), 0, width), height/2);

  noFill();

  // push();

  // translate(width/2, height/2);

  // rotate(45);

  line(0, height/2, width/2, 0);

  line(0, height/2, width/2, height);

  line(width/2, 0, width, height/2);

  line(width/2, height, width, height/2);

  // rect(0, 0, sqrt(sq(width/2) * 2), sqrt(sq(width/2) * 2));

  // pop();

}