THREE.JS 实现场景天空包围盒，为了让场景背景更具体，而不是呆板的纯色，可以给厂家添加围绕的包围盒。

• 这里使用球体来实现，球体中央则是场景
• 给球体添加天空的渐变色
• 加入场景

代码如下

function createSky( hemiLight) {

  const vertexShader = `varying vec3 vWorldPosition;

    void main() {

        vec4 worldPosition = modelMatrix * vec4( position, 1.0 );

        vWorldPosition = worldPosition.xyz;

        gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );

    }`

  const fragmentShader = `uniform vec3 topColor;

    uniform vec3 bottomColor;

    uniform float offset;

    uniform float exponent;

    varying vec3 vWorldPosition;

    void main() {

        float h = normalize( vWorldPosition + offset ).y;

        // 从-0.2 到1做渐变

        h = smoothstep(-0.4, 1.0, h);  

        gl_FragColor = vec4( mix( bottomColor, topColor, max( pow( max( h , 0.0), exponent ), 0.0 ) ), 1.0 );

    }`

  const uniforms = {

    'topColor': { value: new THREE.Color(0x0077ff) },

    'bottomColor': { value: new THREE.Color(0xeeeeee) },

    'offset': { value: 30 },

    'exponent': { value: 0.6 }

  }

  uniforms['topColor'].value.copy(hemiLight.color)

  // scene.fog.color.copy( uniforms[ 'bottomColor' ].value );

  const skyGeo = new THREE.SphereGeometry(4000, 32, 15)

  const skyMat = new THREE.ShaderMaterial({

    uniforms: uniforms,

    vertexShader: vertexShader,

    fragmentShader: fragmentShader,

    side: THREE.BackSide

  })

  const sky = new THREE.Mesh(skyGeo, skyMat)

  return sky

}