How to texture the inside of a sphere (or cylinder or cube)

I might be extremely dumb but I still don't grasp how I can apply a texture inside a shape in Unity3D. Same, I want to have a collider INSIDE the object AND outside the object. If only I could find how to do this !

Someone answers very laconically on the forum about normal... But no specification.

Imagine a city under a dome. I want to be able to see the dome from inside (I am presently using particles but it is not satisfying) and outside. I would like to have a collider at least inside the dome (to avoid going out of the place).

If it is not possible for a shape to have 2 of these properties simultaneously, no pb, I will use 2 shapes with one slightly smaller for the inside. But how to affect texture and collider INSIDE. I am sure the answer might be very simple.

Not sure about the textures - but I know how to have two colliders, one inside and one outside.

Okay, So you have your sphere, already with a sphere collider right? This will be the outer collider, so make it bigger than it already is. Next, create a game empty, and drag this into your sphere (so its a child). Change the position of the empty to 0, 0, 0 in the Inspector, then add a sphere collider to this: Component > Physics > Sphere collider, and make the radius of this smaller (inside collider).

Hope that helps.

Yes, it's very simple...just model both the inside and outside.

As Eric5h5 said, just model your dome and in whatever software you use apply a Normals modifier and flip the normals.

You could also just use a cubemap for the background image and create a custom mesh for the collisions.