JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/92/three.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/gpu.js/1.2.0/gpu.min.js"></script>
<script src="https://rawgit.com/mrdoob/three.js/master/examples/js/loaders/OBJLoader.js"></script>

CSS

body { 
	margin: 0; 
	background-color: darkgrey;
}
canvas {
	background-color: white;
}

JavaScript

var container;
var camera, scene, renderer;
var mouseX = 0;
var mouseY = 0;
var scale = 4;
var windowHalfX = window.innerWidth / 2;
var windowHalfY = window.innerHeight / 2;
var smallWidth = Math.floor(window.innerWidth / scale);
var smallHeight = Math.floor(window.innerHeight / scale);

var width = smallWidth * scale;
var height = smallHeight * scale;


var rt = new THREE.WebGLRenderTarget(smallWidth, smallHeight);
var frameBuffer = new Uint8Array(smallHeight * smallHeight * 4);
var outputBuffer = new Uint8ClampedArray(width * height * 4);
var output;
var divisor = 2;
var divisorHalf = divisor / 2;
var negativeDivisorHalf = -1 * divisorHalf;
var canvas;
var context;
var gpu = new GPU();

var pixelateMatrix = gpu.createKernel(function(inputBuffer, width, height, scale) {
/*   var y = Math.floor((this.thread.x / (width[0] * 4)) / scale[0]);
  var x = Math.floor((this.thread.x % (width[0] * 4)) / scale[0]);
  var remainder = this.thread.x % 4;
  return inputBuffer[(x * y) + remainder];
   */
   var size = width[0] * height[0] * 4;
   var current_index = Math.floor((size - this.thread.x)/4); 
   var row = Math.floor(current_index / (width[0] * scale[0]) );
   var col = Math.floor((current_index % width[0])/scale[0]);
   var index_old = Math.floor(row * (width[0] / scale[0])) + width[0] - col;
   var remainder = this.thread.x % 4;
   return inputBuffer[index_old * 4 + remainder];
   
}).setOutput([width * height * 4]);
console.log(window.innerWidth);
console.log(window.innerHeight);
init();
animate();

function init() {
  container = document.createElement('div');
  document.body.appendChild(container);
  canvas = document.createElement('canvas');
  document.body.appendChild(canvas);
  context = canvas.getContext('2d');
  canvas.width = width;
  canvas.height = height;
  camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 1, 2000);
  camera.position.z = 100;

  // scene
  scene = new THREE.Scene();
  var ambient = new...