​

let moving = []; 

let diameter = 8; // diameter of all particles

let iterations = 100;

let col;

let done = false;

let c1, c2, c3, c4, c5;

let maxWalkers;

​

​

// quadtree

let qtree;

​

​

​

function setup() {

  createCanvas(500, 500);

  frameRate(60);

  noStroke();

  // # Sketch settings

  maxWalkers = width *1.5;

  // # Color Palette

  c1 = color(255, 205, 178);

  c2 = color(255, 180, 162);

  c3 = color(229, 152, 155);

  c4 = color(181, 131, 141);

  c5 = color(109, 104, 117);

  init();

}

​

function init(){

  col = 0;

    // # create quadtree

  let boundary = new Rectangle(width/2, height/2, width, height);

  qtree = new QuadTree(boundary, 4);

​

  // # create first fixed particle in the center of the sketch

  let first = new Particle(width/2,height/2)

  first.col = (-cos(col) + 1)/2;

  qtree.insert(first);

​

  for (var i = 0; i < maxWalkers; i++) {

    moving[i] = new Particle();

  }

}

​

function mouseClicked() { 

  init();

} 

​

function draw() {

  background(c5,255); // Draw Background

​

  // # Display all moving particles

  fill(200,10);

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

    moving[i].render();

  }

​

  for (let j = 0; j < iterations; j++) {

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

      moving[i].update(); // Update position

      // quadtree search

      //let range = new Circle(moving[i].pos.x, moving[i].pos.y, diameter); // DO I NEED 2 PUT DIAMETER OR HIGHR

      let fixed = qtree.query(new Circle(moving[i].pos.x, moving[i].pos.y, diameter));

      // collision check

      if (moving[i].collision(fixed)) {

        col += 1/maxWalkers ;

        moving[i].col = col;

        qtree.insert(moving[i]);

        moving.splice(i, 1);

      }

    }

  }

  qtree.renderPoints();

​

}

​

// Custom Functions

​

function distSq(a, b) {

  return (b.x - a.x) ** 2 + (b.y - a.y) ** 2;

}

​

function lerpColorThree(c1, c2, c3, i)

{

  return ((i <= 0.5) ? lerpColor(c1,c2, i*2) : lerpColor(c2,c3, (i-0.5)*2));

}

​

function lerpColorFive(c1, c2, c3, c4, c5, i)

{

  if(i <= 0.25)       {return lerpColor(c1,c2, map(i,0,0.25,0,1));}

  else if(i <= 0.5)   {return lerpColor(c2,c3, map(i,0.25,0.5,0,1));}

  else if(i <= 0.75)  {return lerpColor(c3,c4, map(i,0.5,0.75,0,1));}

  else                {return lerpColor(c4,c5, map(i,0.75,1,0,1));}

}

​

// ##### Particle Prototype

​

class Particle {

  constructor(x,y) {

    if (arguments.length == 2) {

      this.pos = createVector(x,y);

​

    } else {

      let r = int(random(0,4));

      if( r == 0 ) {this.pos = createVector(random(0,width),0)} // north

      if( r == 1 ) {this.pos = createVector(random(0,width),height)} // south

      if( r == 2 ) {this.pos = createVector(0,random(0,height))} // west

      if( r == 3 ) {this.pos = createVector(width,random(0,height))} // east

​

    }

  }

​

  update() {

    var vel = p5.Vector.random2D();

    var tow = createVector(width/2 - this.pos.x, height/2 - this.pos.y); // towards aggregation 

    vel.add(tow.setMag(0.01));

    this.pos.add(vel);

​

    // # constrain

    //this.pos.x = constrain(this.pos.x, 0, width); 

    //this.pos.y = constrain(this.pos.y, 0, height);

  }

​

  collision(others) { 

    for (var i = 0; i < others.length; i++) { 

      // # calculate distance between [this] particle and every fixed particle

      let d = (this.pos.x - others[i].pos.x) ** 2 + (this.pos.y - others[i].pos.y) ** 2;

      //let d = distSq(this.pos, others[i].pos);

      if (d < diameter ** 2) { // if collision

        return true;

      }

    }

  }

​

  render() {

    circle(this.pos.x, this.pos.y, diameter);

  }

}

​

// ##### Quadtree Helper Classes

​

class Rectangle {

  constructor(x, y, w, h) {

    this.x = x;

    this.y = y;

    this.w = w;

    this.h = h;

  }

​

  contains(point) {

    return (point.pos.x >= this.x - this.w &&

      point.pos.x <= this.x + this.w &&

      point.pos.y >= this.y - this.h &&

      point.pos.y <= this.y + this.h);

  }

​

  intersects(range) {

    return !(range.x - range.w > this.x + this.w ||

      range.x + range.w < this.x - this.w ||

      range.y - range.h > this.y + this.h ||

      range.y + range.h < this.y - this.h);

  }

}

​

class Circle {

  constructor(x, y, r) {

    this.x = x;

    this.y = y;

    this.r = r;

  }

​

  contains(point) {

    //let d = distSq(point.pos, createVector(this.x,this.y));

    let d = (point.pos.x - this.x) ** 2 + (point.pos.y - this.y) ** 2;

    return d <= this.r ** 2;

  }

​

  intersects(range) {

​

    var xDist = Math.abs(range.x - this.x);

    var yDist = Math.abs(range.y - this.y);

​

    // radius of the circle

    var r = this.r;

​

    var w = range.w;

    var h = range.h;

​

    var edges = (xDist - w) ** 2 + (yDist - h) ** 2;

​

    // no intersection

    if (xDist > (r + w) || yDist > (r + h))

      return false;

​

    // intersection within the circle

    if (xDist <= w || yDist <= h)

      return true;

​

    // intersection on the edge of the circle

    return edges <= this.r ** 2;

  }

}

​

// ##### Quadtree Class

​

class QuadTree {

  constructor(boundary, capacity) {

    if (!boundary) {

      throw TypeError('boundary is null or undefined');

    }

    if (!(boundary instanceof Rectangle)) {

      throw TypeError('boundary should be a Rectangle');

    }

    if (typeof capacity !== 'number') {

      throw TypeError(`capacity should be a number but is a ${typeof capacity}`);

    }

    if (capacity < 1) {

      throw RangeError('capacity must be greater than 0');

    }

    this.boundary = boundary;

    this.capacity = capacity;

    this.points = [];

    this.divided = false;

  }

​

  subdivide() {

    let x = this.boundary.x;

    let y = this.boundary.y;

    let w = this.boundary.w / 2;

    let h = this.boundary.h / 2;

​

    let ne = new Rectangle(x + w, y - h, w, h);

    this.northeast = new QuadTree(ne, this.capacity);

    let nw = new Rectangle(x - w, y - h, w, h);

    this.northwest = new QuadTree(nw, this.capacity);

    let se = new Rectangle(x + w, y + h, w, h);

    this.southeast = new QuadTree(se, this.capacity);

    let sw = new Rectangle(x - w, y + h, w, h);

    this.southwest = new QuadTree(sw, this.capacity);

​

    this.divided = true;

  }

​

  insert(point) {

    if (!this.boundary.contains(point)) {

      return false;

    }

​

    if (this.points.length < this.capacity) {

      this.points.push(point);

      return true;

    }

​

    if (!this.divided) {

      this.subdivide();

    }

​

    if (this.northeast.insert(point) || this.northwest.insert(point) ||

      this.southeast.insert(point) || this.southwest.insert(point)) {

      return true;

    }

  }

​

  query(range, found) {

    if (!found) {

      found = [];

    }

​

    if (!range.intersects(this.boundary)) {

      return found;

    }

​

    for (let p of this.points) {

      if (range.contains(p)) {

        found.push(p);

      }

    }

    if (this.divided) {

      this.northwest.query(range, found);

      this.northeast.query(range, found);

      this.southwest.query(range, found);

      this.southeast.query(range, found);

    }

​

    return found;

  }

​

  renderPoints(){

    for(let p of this.points){

      let l = lerpColorFive(c1,c2,c3,c4,c5, p.col);

      fill(l,255);

      circle(p.pos.x,p.pos.y,diameter);

    }

​

    if (this.divided) {

      this.northwest.renderPoints();

      this.northeast.renderPoints();

      this.southwest.renderPoints();

      this.southeast.renderPoints();

    }

  }

  renderQuads(){

    if (this.divided) {

      this.northwest.renderQuads();

      this.northeast.renderQuads();

      this.southwest.renderQuads();

      this.southeast.renderQuads();

    }

    else{        

      rect(this.boundary.x, this.boundary.y, this.boundary.w*2-3, this.boundary.h*2-3); 

    }

  }

}

​

​