var points = [];

​

//points on the hull

var hullPoints = [];

​

var leftMost;

​

//current vertex on hull

var currentHullPoint;

​

//current point we're checking

var index;

​

var nextIndex = -1;

var nextPoint;

var checking;

​

var clients = {};

var cursors = [];

var id;

//var socket = io();

var lastEmit, now;

var Lines = [];

var cursor;

var inactivityThreshold;

var drawing;

​

//=================================================================

function setup() {

  createCanvas(windowWidth, windowHeight);

  console.log("setup");

  prev = {};

  inactivityThreshold = 60000;

  lastEmit = 0;

  drawing = 1.0;

​

  //console.log(clients);

  //create vector list for client mouse positions

  for (let i = 0; i < 5; i++) {

    points.push(createVector(random(windowWidth), random(windowHeight)));

    //console.log(points);

  }

​

  leftMost = findLeftMost(points);

  //console.log(leftMost);

  currentHullPoint = leftMost;

  nextPoint = points[1];

  index = 2;

}

​

//=================================================================

function draw() {

  background(255);

  now = millis();

​

  var myPoint = createVector(mouseX, mouseY);

  points.push(myPoint);

​

​

​

  //calculateHull

  for (point in points) {

    var hullPoints = calculateHull(leftMost, points);

  }

  //draw hull

  drawHull(hullPoints);

​

  for (point in points) {

    ellipse(points[point].x, points[point].y, 5, 5);

  }

  //draw the points

  for (var c in clients) {

    var cx = clients[c].x;

    var cy = clients[c].y;

    fill(255);

    ellipse(cx, cy, 10, 10);

    fill(0);

    ellipse(mouseX, mouseY, 10, 10);

  }

}

​

//=================================================================

​

function findLeftMost(points) {

  //find leftmost point by comparing each client's x-val

  points.sort((a, b) => a.x - b.x);

  leftMost = points[0];

  hullPoints.push(leftMost);

  //console.log("leftmost:", leftMost);

  return leftMost;

}

​

//=================================================================

​

function calculateHull(leftMost, points) {

  //calculates hull and returns a list

  let checking = points[index];

  const a = p5.Vector.sub(nextPoint, currentHullPoint);

  const b = p5.Vector.sub(checking, currentHullPoint);

  const crossProd = a.cross(b);

  if (crossProd.z < 0) {

    nextPoint = checking;

    nextIndex = index;

  }

  index += 1;

  if (index == points.length) {

    hullPoints.push(nextPoint);

    currentHullPoint = nextPoint;

    index = 0;

    nextPoint = leftMost;

  }

  //console.log(hullPoints);

  return hullPoints;

}

​

//=================================================================

​

function drawHull(hullPoints) {

  //for(var j = 0; j< hullPoints.length; j++) {

  //line(hullPoints[j].x, hullPoints[j].y, hullPoints[j+1].x,hullPoints[j+1].y);

  //}

​

  stroke(0, 0, 255);

  fill(0, 0, 255, 50);

  beginShape();

  for (let p of hullPoints) {

    vertex(p.x, p.y);

  }

  endShape();

​

}

​

function keyPressed(){

  points = [];

}