// Coding Challenge from CodingTrain

​

// Gift Wrapping Algorithm

// My own take!

​

let spacing;

let points;

let giftP;

let angle;

let currentP;

let nextPoint;

let leftMost;

let end;

​

​

let numOfPoints = 80; // Number of starting points

let speed = 0.005; // speed with which the angle changes

let precision = 100; // value threashold for the z during a cross product to be considered a parallel vector

​

function setup() {

  createCanvas(windowWidth, windowHeight);

   spacing = windowWidth * 0.05;

  reset();

}

​

function draw() {

  background(0);

  fill(255);

  noStroke();

  frameRate(30);

  for (let i = 0; i < points.length; i++) {

    ellipse(points[i].x, points[i].y, 4, 4);

  }

​

  stroke(255);

  strokeWeight(3);

  if(end) {

   fill(0,255,100,10); 

  }else{

    noFill()

  }

  beginShape();

  for (let i = 0; i < giftP.length; i++) {

    vertex(giftP[i].x, giftP[i].y);

  }

  endShape();

​

  if (!end) {

​

    for (let i = 0; i < giftP.length; i++) {

      fill(255, 0, 255);

      ellipse(giftP[i].x, giftP[i].y, 8, 8);

    }

​

    push();

    translate(currentP.x, currentP.y);

    let x = -100 * cos(angle);

    let y = -100 * sin(angle);

    let currentV = createVector(x, y);

    stroke(0, 255, 0, 255);

    strokeWeight(2);

    line(0, 0, x, y);

​

    for (let i = 0; i < points.length; i++) {

​

      let px = points[i].x - currentP.x;

      let py = points[i].y - currentP.y;

      let cp = createVector(px, py);

      stroke(0, 255, 120, 50);

      strokeWeight(1);

      line(0, 0, px, py);

​

      let a = p5.Vector.cross(currentV, cp);

      if (abs(a.z) < precision && px != 0 && (points[i] != leftMost || giftP.length > 3)) {

      console.log("precision = " + abs(a.z));

​

        nextPoint = points[i];

​

        if (nextPoint != leftMost) {

​

          points.splice(i, 1);

​

        } else {

          console.log("END");

          end = true;

        }

        break;

      }

    }

    pop();

    angle += speed;

​

    if (nextPoint != null) {

      currentP = nextPoint;

      giftP.push(currentP);

      nextPoint = null;

    } else if (end) {

      currentP = leftMost;

    }

​

  } else {

​

    setTimeout(reset, 3000);

  }

}

​

function reset() {

  giftP = [];

  points = [];

  nextPoint = null;

  currentP = null;

  leftMost = createVector(width + spacing, 0);

  angle = PI / 2

​

  for (let i = 0; i < numOfPoints; i++) {

    let x = floor(random(spacing, width - spacing));

    let y = floor(random(spacing, height - spacing));

    let point = createVector(x, y);

    points.push(point);

    if (point.x < leftMost.x) {

      leftMost = point;

    }

  }

​

  giftP.push(leftMost);

​

  currentP = leftMost;

​

  end = false;

}