Update: replacing the light by a HemisphericLight it worked (I may have some normal inverted though):
var light = new BABYLON.HemisphericLight("HemiLight", new BABYLON.Vector3(0, 1, 0), scene);
Figured out by reading the following post:
Update: replacing the light by a HemisphericLight it worked (I may have some normal inverted though):
var light = new BABYLON.HemisphericLight("HemiLight", new BABYLON.Vector3(0, 1, 0), scene);
Figured out by reading the following post: