使用 Three.js 实现**雷达扫描着色器**，具体要求：

【核心特效】
- 360度旋转扫描线
- 扫描尾迹渐变消失效果
- 单一颜色配置
- 简洁的雷达显示效果

【场景与光照】
- 深灰色背景 (#1f1f1f)
- 从上方俯视角度 (相机位置 y=800, z=1000)
- OrbitControls 轨道控制器
- 自定义材质实现扫描动画

【交互与控制】
- OrbitControls 鼠标拖拽旋转
- 鼠标滚轮缩放
- 自动播放扫描动画

【技术要求】
- Three.js 版本 (ES Module)
- MeshBasicMaterial + onBeforeCompile 实现自定义着色器
- 使用 `atan()` 函数计算角度
- 实时更新的 uniform 时间变量

float calcAngle(vec3 oFrag) {
  float fragAngle;
  const vec3 ox = vec3(1, 0, 0);

  float dianji = oFrag.x * ox.x + oFrag.z * ox.z;
  float oFrag_length = length(oFrag);
  float ox_length = length(ox);
  float yuxian = dianji / (oFrag_length * ox_length);

  fragAngle = acos(yuxian);
  fragAngle = degrees(fragAngle);

  if(oFrag.z > 0.0) {
    fragAngle = -fragAngle + 360.0;
  }

  float scanAngle = uTime * uSpeed - floor(uTime * uSpeed / 360.0) * 360.0;
  float angle = scanAngle - fragAngle;
  if(angle < 0.0) {
    angle = angle + 360.0;
  }

  return angle;
}

void main() {
  #include <opaque_fragment>

  if(length(vPosition) == 0.0 || length(vPosition) > uRadius - 2.0) {
    gl_FragColor = vec4(outgoingLight, diffuseColor.a);
  } else {
    float angle = calcAngle(vPosition);

    if(angle < uFollowWidth) {
      float opacity = 1.0 - angle / uFollowWidth;
      gl_FragColor = vec4(outgoingLight, diffuseColor.a * opacity);
    } else {
      gl_FragColor = vec4(outgoingLight, 0.0);
    }
  }
}

const circleGeometry = new THREE.CircleGeometry(radarData.radius, 1000);
const rotateMatrix = new THREE.Matrix4().makeRotationX((-Math.PI / 180) * 90);
circleGeometry.applyMatrix4(rotateMatrix);

material.onBeforeCompile = (shader) => {
  Object.assign(shader.uniforms, {
    uSpeed: { value: radarData.speed },
    uRadius: { value: radarData.radius },
    uTime: { value: 0 },
    uFollowWidth: { value: radarData.followWidth }
  });

  requestAnimationFrame(function update(time) {
    shader.uniforms.uTime.value = time / 1000;
    requestAnimationFrame(update);
  });

  shader.vertexShader = shader.vertexShader.replace('void main() {',
    `varying vec3 vPosition;
     void main() {
       vPosition = position;
  `);

  shader.fragmentShader = shader.fragmentShader.replace('void main() {',
    `uniform float uRadius;
     uniform float uTime;
     uniform float uSpeed;
     uniform float uFollowWidth;
     varying vec3 vPosition;

     float calcAngle(vec3 oFrag) {
       // ... 计算逻辑
     }

     void main() {
  `);
};

const radarData = {
  position: { x: 0, y: 20, z: 0 },
  radius: 240,
  color: '#f005f0',
  opacity: 0.5,
  speed: 300,
  followWidth: 220
};