example/scene/index.html

<head>
  <style> body { margin: 0; } </style>

  <script src="//unpkg.com/3d-force-graph"></script>
  <!-- <script src="../../dist/3d-force-graph.js"></script> -->
</head>

<body>
  <div id="3d-graph"></div>

  <script type="module">
    import * as THREE from 'https://esm.sh/three';

    // Random tree
    const N = 30;
    const gData = {
      nodes: [...Array(N).keys()].map(i => ({ id: i })),
      links: [...Array(N).keys()]
        .filter(id => id)
        .map(id => ({
          source: id,
          target: Math.round(Math.random() * (id-1))
        }))
    };

    const graph = new ForceGraph3D(document.getElementById('3d-graph'))
        .graphData(gData);

    const planeGeometry = new THREE.PlaneGeometry(1000, 1000, 1, 1);
    const planeMaterial = new THREE.MeshLambertMaterial({color: 0xFF0000, side: THREE.DoubleSide});
    const mesh = new THREE.Mesh(planeGeometry, planeMaterial);
    mesh.position.set(-100, -200, -100);
    mesh.rotation.set(0.5 * Math.PI, 0, 0);

    graph.scene().add(mesh);
  </script>
</body>