Help with planes in BGE

Hello, Ive realized that planes (mesh) dont have two sided normals. If I have a room I can only look at it from the outside, if I go inside the walls are transparent. Is there a way to have doubl sided normals?

Disable the backface culling option in the material tab.

In the Game Settings options in Material properties, disable Backface Culling.

You can actually make a face show up on both sides, but it will share the texture. However, I wouldn’t recommend you make ur wall a flat plane. The best way is to add a different set of planes for interior walls, which will give the room the thickness it realistically needs.

If you still want to make both sides visible, you can go into the materials tab, scroll down to “game settings” and uncheck “backface culling”.

I agree with Dhaher, using backface culling will force you to build realistic walls and buildings, and I believe if you do uncheck backface culling you will get a slight drop in performance because blender has to render both sides instead of just one.

actually, you can use SDFgeoff’s new script for dynamic loading, and load the inside, when inside, and the outside, when outside :smiley:

Ya, but if the inside is not using backface culling you will take a performance hit (I think).

Besides, Ordunok is trying to build a room that he goes in and out of, meaning that when he enters a room all he’s going to see when passing the wall is a flat 2d plane. You don’t wanna design building like that.

what I meant, is that inside, you load the inside geometry only, and remove it when outside, using a hall and a set of planes,

Yes BPR, that’s what I thought you were saying, so I still know how that applies to backface culling.

Looking at Ordunok’s question a little closer I see maybe his problem is just not knowing how to flip normals, since he siad when he goes inside everything is transparent. If that’s it, all you have to do is select the geometry of the room in edit mode, press W, and flip normals.

No, the problem is that its always transparent on some side (not double sided), is there a way to have it doublesided without it sharing the textures?

Can be done with a simple node setup and 2 materials:


Create two planes facing different directions.

= double the poly count. Material based solution is the best in this case.

A two-sided face consists of two faces.

Render engines use one side only to avoid unnecessary rendering. So it is assumed that you never can see the back of a face. Rendering can be skipped and quite a lot of processing time is saved.

Using two-side option contradicts this assumption. There are very rare situatios when you really need that. Examples are very thin objects like paper, capes or curtains.

Walls are usually not made of paper. They do not even look well if they have no depth. As they are usually very straight, you should not be able to see both sides at the same time. So do not be lazy - model the inside, the outside and the thickness too.

I would say don’t use backface culling at all if you want your game to be super efficient, even with curtains and paper. If you’re going for the best possible options for a game, then you’re going to want to have texture atlases to cut down on draw calls, so if you have a curtain on a texture atlas and you disable backface culling all of the other objects that share that texture are going to have to render both sides of everything. Besides modeling things like curtains realistically is much better for, um…realism.

If you really have to then have a texture atlas just for things that you know will need both sides rendered like Monster said, papers and such.