Hi Everybody !
I am not sure this is a bug or a wanted behavior, that is why I did not post on the bug section.
When you set the property infiniteDistance to true on a skybox created from the meshBuilder, then behavior is as expected : http://www.babylonjs-playground.com/#UU7RQ#66
But when you set the same property of a skybox create from an EnvironmentHelper, then it changes nothing : https://www.babylonjs-playground.com/#10D6YT#74
I saw in the source code of the TransformNode (line 735) that the parent attribute of the skybox is tested. Of course with the EnvironmentHelper it is not null.
It is on purpose ?
"Solution" found while writing this post : Obviously I can get the skybox from the environmentHelper and set its parent to null, but it doesn't looks clean coding to me.
Except this, EnvironmentHelper is awesome to set up clean scene really fast ! I love it.