全景播放器实现流程及原理

效果展示

原理

生成一个圆形球体并将相机置于球体内部，通过将全景图片映射到球体中并将图片朝向至球体内部这样就实现了全景图片的查看，全景视频是通过将视频的每一帧生成一张纹理单元按照球体的uv在片元着色器内进行展开

全景视频加载流程

1. 创建圆形网格球体（SphereGeometry球体生成改变widthSegments、heightSegments使得球体更加平滑）

    const geometry = new THREE.SphereGeometry(500,1000,1000);
    geometry.scale(-1, 1, 1); 
    //翻转内部

2. 创建一个视频元素用来加载全景视频

    const video = document.createElement('video');
    video.crossOrigin = 'anonymous';
    video.src = url

3. 创建视频的纹理并设置纹理的线性过滤器及颜色格式

    const texture = new THREE.VideoTexture(video);
    texture.minFilter = THREE.LinearFilter;
    texture.magFilter = THREE.LinearFilter;
    texture.format = THREE.RGBFormat;

4. 通过Three.js内部的着色器将视频纹理单元添加至网格球体中

    const material = new THREE.MeshBasicMaterial({ map: texture });
    const sphere = new THREE.Mesh(geometry, material);
    scene.add(sphere);

5. 更新视频纹理并渲染

    function update() {
      if (video.readyState === video.HAVE_ENOUGH_DATA) {
        texture.needsUpdate = true;
      }
      requestAnimationFrame(update);
    }
    update();
    function animate() {
      requestAnimationFrame(animate);
      renderer.value.render(scene, camera.value);
    }
    animate();

全景片加载流程

1. 创建圆形网格球体

    const geometry = new THREE.SphereGeometry(500,1000,1000);
    geometry.scale(-1, 1, 1); 
    //翻转内部

2. 读取图片并将图片转换为纹理添加至网格球体中

    const texture = new THREE.TextureLoader().load(url);
    const material = new THREE.MeshBasicMaterial({ map: texture });
    const sphere = new THREE.Mesh(geometry, material);
    scene.add(sphere);

3.渲染

    function animate() {
      requestAnimationFrame(animate);
      renderer.value.render(scene, camera.value);
    }
    animate();

完整代码