index.html

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Pyramid Demo</title>
<script src="https://cdn.jsdelivr.net/npm/three@0.132.2/build/three.min.js"></script>
</head>
<body>
<button onclick="activateXR()">Start Pyramid Demo</button>
<script>
async function activateXR() {
  const canvas = document.createElement("canvas");
  document.body.appendChild(canvas);
  const gl = canvas.getContext("webgl", {xrCompatible: true});
  
  const scene = new THREE.Scene();
  
  const materials = [
    new THREE.MeshBasicMaterial({color: 0xff0000}),
    new THREE.MeshBasicMaterial({color: 0x0000ff}),
    new THREE.MeshBasicMaterial({color: 0x00ff00})
  ];
  
  const pyramidGeometry = new THREE.ConeBufferGeometry(0.5, 1, 4, 1);
  const pyramid = new THREE.Mesh(pyramidGeometry, materials);
  pyramid.position.set(0, 0, -1);
  scene.add(pyramid);
  
  const renderer = new THREE.WebGLRenderer({
    alpha: true,
    preserveDrawingBuffer: true,
    canvas: canvas,
    context: gl
  });
  renderer.autoClear = false;
  
  const camera = new THREE.PerspectiveCamera();
  camera.matrixAutoUpdate = false;
  
  const session = await navigator.xr.requestSession("immersive-ar");
  session.updateRenderState({
    baseLayer: new XRWebGLLayer(session, gl)
  });
  
  const referenceSpace = await session.requestReferenceSpace('local');
  
  const onXRFrame = (time, frame) => {
    session.requestAnimationFrame(onXRFrame);
    
    gl.bindFramebuffer(gl.FRAMEBUFFER, session.renderState.baseLayer.framebuffer);
    
    const pose = frame.getViewerPose(referenceSpace);
    if (pose) {
      const view = pose.views[0];
      
      const viewport = session.renderState.baseLayer.getViewport(view);
      renderer.setSize(viewport.width, viewport.height);
      
      camera.matrix.fromArray(view.transform.matrix);
      camera.projectionMatrix.fromArray(view.projectionMatrix);
      camera.updateMatrixWorld(true);
      
      renderer.render(scene, camera);
    }
  }
  session.requestAnimationFrame(onXRFrame);
}
</script>
</body>
</html>