A demonstration of how to create building windows transparent from one side.
It replaces a given material (in our case called “Glass”) with a custom material with a custom simple shader, which sets transparency and tint from one side only. The other side uses a reflection texture.
Edit: I used this technique in my project on a standalone building with no surroundigs, there are just some trees behind it and the camera is not allowed to rotate to see the backside of the building so the user is not able to notice, that there are not reflections of the trees. The reflection texture is sort of just an abstract environment with gradients.
One might want to change the projection coordinates type for the reflection texture. It can be done like this:
customGlassMaterial.reflectionTexture.coordinatesMode = BABYLON.Texture.CUBIC_MODE
Or you can use diffuseTexture with a fake mirror texture, or just diffuseColor.