Question about fog in 3D tunnels

[A7]

I've seen it hundreds of times before. I know how to fake the surrounding terrain for an underground tunnel. I can model the tunnel for the coaster perfectly. However, when it comes to getting from normal lighting to black to normal again. How? When riding a coaster that features this, it appears to be fog, or complete darkness.. What do I do to achieve that sort of effect?

I believe you take multiple flat planes with foggy textures and position them so that they are on/around the track. I am no 3D expert, so don't take my word for it, but I think that is the idea.

[A7]

I just tried that, and I have to say it is a very effective method. Thanks! I made a flat object that is the same shape as the tunnel. Put a dark/transparent 'cloudy' texture on it. Copy and Pasted a bunch of times, placed them, and it works. The closer the objects are to each other, the darker that particular area appears. So if they are more or less spread out at the start of the tunnel, densely placed in the middle, and then spread out again towards the end you get a very realistic effect.

[AyTrane]

You could reduce the object count by making a plane with x-number of segments. Then fold the segments back and forth over the track in a zig zag manner.

[A7]

Thanks for the tip.[^]