求助：怎么动态调整环境光亮度

Creator 3.x
#1

代码如下，控制台输出值是改了，但是游戏里没有变，我是不是少了哪一步？
if (AmbientInfo.prototype.skyIllum == 0) {
AmbientInfo.prototype.skyIllum = 2222;
} else {
AmbientInfo.prototype.skyIllum = 0;
}
console.log(AmbientInfo.prototype.skyIllum);

#2

已解决：director.getScene().globals.ambient.skyIllum = 30000

#3

新的问题：web端报错：[Browser Preview]Cannot read properties of null (reading ‘globals’)/nTypeError: Cannot read properties of null (reading ‘globals’)