let yvals = [];

let bvals = [];

​

function setup() {

  createCanvas(720, 400);

  strokeWeight(2);

}

​

function draw() {

  background(237, 34, 93);

​

  for (let i = 1; i < width; i++) {

    xvals[i - 1] = xvals[i];

    yvals[i - 1] = yvals[i];

    bvals[i - 1] = bvals[i];

  }

  // Add the new values to the end of the array

  xvals[width - 1] = mouseX;

  yvals[width - 1] = mouseY;

​

  if (mouseIsPressed) {

    bvals[width - 1] = 0;

  } else {

    bvals[width - 1] = 255;

  }

​

  fill(255);

  noStroke();

  rect(0, height / 3, width, height / 3 + 1);

​

  for (let i = 1; i < width; i++) {

    stroke(255);

    point(i, xvals[i] / 3);

    stroke(0);

    point(i, height / 3 + yvals[i] / 3);

    stroke(255);

    line(

      i,

      (2 * height) / 3 + bvals[i] / 3,

      i,

      (2 * height) / 3 + bvals[i - 1] / 3

    );

  }

}

​