<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
<style>
</style>
</head>
<body>

<script src="https://twgljs.org/dist/4.x/twgl-full.min.js"></script>
<canvas id="canvas"></canvas>


</body>
<script>

async function main() {
  const gl = document.querySelector('canvas').getContext('webgl');
  
  const m4 = twgl.m4;
  const v3 = twgl.v3;
  const vs = `
  attribute vec4 position;
  attribute vec2 texcoord;

  uniform