When working on a game, I accidentally came across something pretty cool that could be used to create one-way glass without messing around with transparency or decals (as I’ve seen in other solutions). It’s a relatively simple technique and I’ve seen interest in one-way glass across the forum so I thought it would be worth sharing with everyone.
How to create the one-way glass
In a new Blender project, go into edit mode and remove one of the faces on the default cube. Export it out of Blender and import the mesh into Roblox.
Cube in Blender
That’s pretty much it. You can resize and color it how you want, and whenever you look from the side with the missing face, you will be able to see right through. You can even remove more faces or all but one of them to create 2D (flat) one-way glass, but I find it easier to work with a 3D box rather than a 2D rectangle.
Imported mesh in Roblox Studio
In the images below, you can see how I’ve resized it and added a few parts around it to make it look better.
Final product
You could even add a semi-transparent part on the front to make it actually look like a window. The shadow of the parts around it sort of gives it away as well, so you could disable them if you would like to.
How it works
This method takes advantage of how mesh “normals” (faces) work. If you have ever created something somewhat complex in Blender and tried importing it to Roblox, you might have seen how some faces on the mesh appear to be see-through.
Example of inverted normals (image credit)
The problem here is that the faces are flipped (they are facing inward), which is a relatively easy fix in Blender. From this, however, we can see that when viewing from the “back” side of a face, you can see right through. By intentionally removing a face from a mesh, you are exposing the back side of the other faces and end up creating a “one-way glass” effect.
Hope this was useful! If you have any questions/thoughts on this or find anything else that could be interesting, please share! I would also love to see any creations utilizing this.