https://www.aliaswavefront.com/en/Tmp...dering_m.html#
click 'How to Create a Realistic Sky with EnvSky' item.
all tell you.
<img src=https://www.philsky.net/HOME/fly/photo/sign_simplymaya.jpg alt=https://www.philsky.net/HOME/fly/photo/sign_simplymaya.jpg>