Collision from inside concave collision shape doesn't work

[kasrakamran]

Godot Version

4.2.2

Question

I’m trying to create collision for the inside of a corridor model.
For this I created a mesh instance (3D), gave it a cube shape and fit it to the size of my model, and then used “Create Trimesh Static Body/Create Trimesh Collision Sibling”.
With either of these, I have a problem where I get collision from outside of the shape, but not from inside, which is the opposite of what I want.

Is there anyway I can get collision from the inside? (other than manually creating a bunch of collision boxes)

P.S.: I don’t know anything about level design at all, so I’d appreciate it if you could give me some pointers for that.)

[coderjo]

Ensure you’ve set the build_mode of the CollisionPolygon2D to solids instead of segments.

[kasrakamran]

Thank you, However, I was more so working with 3D object and a collisionpolygon3D.
What ended up solving my problem is on the CollisionShape3D object enabling back side collision.
After enabling that it works as expected.