ジャパスクリプトで作った背景の固定をしたい

参考サイト
https://deshinon.com/2019/03/06/koseiteki-haikei-css/
このサイトの下の方にある
『スパイダーマンの世界
ただのホバーエフェクトじゃない！糸の中を３Dで動く』

を背景で使いたいのですが
bodyにposition:relative;を付けて要素を一つ一つずらしてかないとできません。。。
背景で固定する｟高さの影響をなくす｠ことは可能なのでしょうか、、？

body{
	background:#f98578;
	position:relative;
	}

<script>
  var mouseX = 0,
      mouseY = 0,
      windowHalfX = window.innerWidth / 2,
      windowHalfY = window.innerHeight / 2,
      SEPARATION = 200,
      AMOUNTX = 10,
      AMOUNTY = 10,
      camera,
      scene,
      renderer;
  
  init();
  animate();

  function init() {

    var container,
        separation = 100,
        amountX = 50,
        amountY = 50,
        particle;
    
    container = document.createElement( 'div' );
    document.body.appendChild( container );

    scene = new THREE.Scene();

    renderer = new THREE.CanvasRenderer({ alpha: true }); // gradient; this can be swapped for WebGLRenderer
    renderer.setSize( window.innerWidth, window.innerHeight );
    container.appendChild( renderer.domElement );
    
    camera = new THREE.PerspectiveCamera(
      75,
      window.innerWidth / window.innerHeight,
      1,
      10000
    );
    camera.position.z = 100;

    // particles
    var PI2 = Math.PI * 2;
    var material = new THREE.SpriteCanvasMaterial({
      color: 0xffffff,
      program: function ( context ) {
        context.beginPath();
        context.arc( 0, 0, 0.5, 0, PI2, true );
        context.fill();
      }
    });
    
    var geometry = new THREE.Geometry();

    for ( var i = 0; i < 100; i ++ ) {
      particle = new THREE.Sprite( material );
      particle.position.x = Math.random() * 2 - 1;
      particle.position.y = Math.random() * 2 - 1;
      particle.position.z = Math.random() * 2 - 1;
      particle.position.normalize();
      particle.position.multiplyScalar( Math.random() * 10 + 450 );
      particle.scale.x = particle.scale.y = 10;
      scene.add( particle );
      geometry.vertices.push( particle.position );
    }

    // lines
    var line = new THREE.Line( geometry, new THREE.LineBasicMaterial( { color: 0xffffff, opacity: 0.5 } ) );
    scene.add( line );

    // mousey
    document.addEventListener( 'mousemove', onDocumentMouseMove, false );
    document.addEventListener( 'touchstart', onDocumentTouchStart, false );
    document.addEventListener( 'touchmove', onDocumentTouchMove, false );
    
    window.addEventListener( 'resize', onWindowResize, false );

  } // end init();

  function onWindowResize() {

    windowHalfX = window.innerWidth / 2;
    windowHalfY = window.innerHeight / 2;

    camera.aspect = window.innerWidth / window.innerHeight;
    camera.updateProjectionMatrix();

    renderer.setSize( window.innerWidth, window.innerHeight );

  }

  function onDocumentMouseMove(event) {

    mouseX = event.clientX - windowHalfX;
    mouseY = event.clientY - windowHalfY;

  }

  function onDocumentTouchStart( event ) {

    if ( event.touches.length > 1 ) {

      event.preventDefault();

      mouseX = event.touches[ 0 ].pageX - windowHalfX;
      mouseY = event.touches[ 0 ].pageY - windowHalfY;

    }
  }

  function onDocumentTouchMove( event ) {

    if ( event.touches.length == 1 ) {

      event.preventDefault();

      mouseX = event.touches[ 0 ].pageX - windowHalfX;
      mouseY = event.touches[ 0 ].pageY - windowHalfY;

    }
  }

  function animate() {
    
    requestAnimationFrame( animate );
    render();
    
  }

  function render() {
    
    camera.position.x += ( mouseX - camera.position.x ) * .05;
    camera.position.y += ( - mouseY + 200 - camera.position.y ) * .05;
    camera.lookAt( scene.position );

    renderer.render( scene, camera );
  
  }
</script>