thank you @MackeyK24 it's better with my single directional light in mixed. I have tested with Coordinates Index 0 and 1, but the result is very different than the unity lightmapping. If you want you can test with this free scene : https://www.assetstore.unity3d.com/en/#!/content/65679 I have fixed a bug in the exporter to export this scene : https://github.com/BabylonJS/Babylon.js/pull/1618 thx, Jeremie.