<!-- Try moving the mouse around and clicking the text area -->
<div id="title-desktop" class="hidden">Made by Truman</div>
<div id="title-mobile" class="hidden">Codepen.io</div>
<canvas id="spring-text"></canvas>
body {
  padding: 0px;
  margin: 0px;
}

.hidden {
  display: none;
}

#spring-text {
  position: absolute;
  left: 0px;
  top: 0px;
  width: 100vw;
  height: 100vh;
}
// WRITTEN BY TRUMAN HEBERLE
var COLOR = "black"
var MESSAGE = document.getElementById("title-desktop").textContent;

var FONT_SIZE = 100;
var AMOUNT = 3000;
var CLEAR_AMOUNT = 2;
var SIZE = 2;
var INITIAL_DISPLACEMENT = 100;
var INITIAL_VELOCITY = 5;
var VELOCITY_RETENTION = 0.95;
var SETTLE_SPEED = 1;
var FLEE_SPEED = 1;
var FLEE_DISTANCE = 50;
var FLEE = true;
var SCATTER_VELOCITY = 3;
var SCATTER = true;

if (/Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent)) {
  // Mobile
  MESSAGE = document.getElementById("title-mobile").textContent;
  
  FONT_SIZE = 50;
  AMOUNT = 300;
  SIZE = 2;
  INITIAL_DISPLACEMENT = 100;
  SETTLE_SPEED = 1;
  FLEE = false;
  SCATTER_VELOCITY = 2;
}

// MAIN
FLEE_SPEED /= 10;
SETTLE_SPEED /= 100;
SCATTER_VELOCITY *= 10;
var CLEAR_RADIUS = Math.round(CLEAR_AMOUNT + SIZE);
var MOVED_O = Array.apply(null, Array(AMOUNT)).map(function () {return null;});

const canvas = document.getElementById("spring-text");
const ctx = canvas.getContext("2d");
var POINTS = [];
var MOVED = [];
var moved_length = 0;
var MOUSE = {
  x: 0,
  y: 0
}

function Point(x,y,r,g,b,a) {
  var angle = Math.random() * 6.28;
  this.dest_x = x;
  this.dest_y = y;
  this.original_r = r;
  this.original_g = g;
  this.original_a = a;
  this.lastx = 0;
  this.lasty = 0;
  this.x = canvas.width/2 - x + (Math.random() - 0.5) * INITIAL_DISPLACEMENT;
  this.y = canvas.height/2 - y + (Math.random() - 0.5) * INITIAL_DISPLACEMENT;
  this.velx = INITIAL_VELOCITY * Math.cos(angle);
  this.vely = INITIAL_VELOCITY * Math.sin(angle);
  this.target_x = canvas.width/2 - x;
  this.target_y = canvas.height/2 - y;
  this.r = r;
  this.g = g;
  this.b = b;
  this.a = a;
  this.moved = false;
  MOVED[moved_length] = this;
  moved_length++;
  
  this.getX = function() {
    return this.x;
  }
  
  this.getY = function() {
    return this.y;
  }
  
  this.fleeFrom = function(x, y) {
    this.velx -= ((MOUSE.x - this.x) * FLEE_SPEED);
    this.vely -= ((MOUSE.y - this.y) * FLEE_SPEED);
  }
  
  this.settleTo = function(x, y) {
    this.velx = VELOCITY_RETENTION * (this.velx + (this.target_x - this.x) * SETTLE_SPEED);
    this.vely = VELOCITY_RETENTION * (this.vely + (this.target_y - this.y) * SETTLE_SPEED);
  }
  
  this.scatter = function() {
    var unit = this.unitVecTo(MOUSE.x, MOUSE.y);
    var vel = SCATTER_VELOCITY * (0.5 + Math.random() / 2);
    this.velx = -unit.x * vel;
    this.vely = -unit.y * vel;
  }
  
  this.checkMove = function() {
    this.moved = (!Math.abs(Math.round(this.target_x - this.x)) == 0 || !Math.abs(Math.round(this.target_y - this.y)) == 0 || !Math.abs(Math.round(this.velx)) == 0 || !Math.abs(Math.round(this.vely)) == 0);
  }
  
  this.simpleMove = function() {
    this.checkMove();
    if (!this.moved) {
      return;
    }
    
    this.lastx = this.x;
    this.lasty = this.y;
    this.x += this.velx;
    this.y += this.vely;
    MOVED[moved_length] = this;
    moved_length++;
  }
  
  this.move = function() {
    if (this.distanceTo(MOUSE.x, MOUSE.y) <= FLEE_DISTANCE) {
      this.fleeFrom(MOUSE.x, MOUSE.y);
    }
    else {
      this.settleTo(this.target_x, this.target_y);
    }
    this.simpleMove();
  }
  
  this.distanceTo = function(x, y) {
    var dx = x - this.x;
    var dy = y - this.y;
    return Math.sqrt(dx*dx+ dy*dy);
  }
  
  this.unitVecTo = function(x, y) {
    var dx = x - this.x;
    var dy = y - this.y;
    var d = Math.sqrt(dx*dx + dy*dy);
    return {
      x: dx / d,
      y: dy / d
    };
  }
  
  this.inMotion = function() {
    return this.moved;
  }
  
  this.clear = function() {
    ctx.clearRect(this.lastx-CLEAR_RADIUS,this.lasty-CLEAR_RADIUS,CLEAR_RADIUS*2,CLEAR_RADIUS*2);
  }
  
  this.draw = function() {
    ctx.fillStyle = "rgba("+this.r+","+this.g+","+this.b+","+this.a+")";
    ctx.beginPath();
    ctx.arc(this.x,this.y,SIZE,0,2*Math.PI);
    ctx.fill();
  }
}

window.addEventListener("resize", function() {
  resizeCanvas()
  adjustText()
});

if (FLEE) {
  window.addEventListener("mousemove", function(event) {
    MOUSE.x = event.clientX;
    MOUSE.y = event.clientY;
  });
}

if (SCATTER) {
  window.addEventListener("click", function(event) {
    MOUSE.x = event.clientX;
    MOUSE.y = event.clientY;
    for (var i=0; i<POINTS.length; i++) {
      POINTS[i].scatter();
    }
  });
}

function resizeCanvas() {
  canvas.width  = canvas.clientWidth;
  canvas.height = canvas.clientHeight;
}

function adjustText() {
  ctx.fillStyle = COLOR;
  ctx.textBaseline = "middle";
  ctx.textAlign = "center";
  ctx.font = FONT_SIZE + "px Arial";
  ctx.fillText(MESSAGE, canvas.width/2, canvas.height/2);
  var textWidth = ctx.measureText(MESSAGE).width;
  if (textWidth == 0) {
    return;
  }
  var minX = canvas.width/2 - textWidth/2;
  var minY = canvas.height/2 - FONT_SIZE/2;
  var data = ctx.getImageData(minX, minY, textWidth, FONT_SIZE).data;
  ctx.clearRect(0,0,canvas.width,canvas.height);
  var isBlank = true;
  for (var i=0; i<data.length; i++) {
    if (data[i] != 0) {
      isBlank = false;
      break;
    }
  }
  
  if (!isBlank) {
    var count = 0;
    var curr = 0;
    var num = 0;
    var x = 0;
    var y = 0;
    var w = Math.floor(textWidth);
    POINTS = [];
    while (count < AMOUNT) {
      while (curr == 0) {
        num = Math.floor(Math.random() * data.length);
        curr = data[num];
      }
      num = Math.floor(num / 4);
      x = w/2 - num%w;
      y = FONT_SIZE/2 - Math.floor(num/w);
      POINTS.push(new Point(x,y,data[num*4],data[num*4 + 1],data[num*4 + 2],data[num*4 + 3]));
      curr = 0;
      count++;
    }
  }
}

function init() {
  resizeCanvas()
  adjustText()
  window.requestAnimationFrame(animate);
}

function animate() {
  update();
  draw();
}

function update() {
  for (var i=0; i<POINTS.length; i++) {
    POINTS[i].move()
  }
}

function draw() {
  for (var i=0; i<moved_length; i++) {
    MOVED[i].clear();
  }
  MOVED = MOVED_O;
  moved_length = 0;
  
  for (var i=0; i<POINTS.length; i++) {
    POINTS[i].draw()
  }
  
  window.requestAnimationFrame(animate);
}

init();

External CSS

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