Inside-out metaballs, off the top of my head. You could use some sort of displacement mapping to make it bumpy.

Tom

Here is a summary of metaballs, including some screen shots. Here is the Siggraph article that links to that summary, and contains a more in-depth description. They are a little complicated, but cool as hell.

Basically, imagine how droplets of liquid mercury behave when they are pushed together, and you have a simple idea of how metaballs work. ParadigmShift is suggesting that you construct your tunnels in this fashion, as a series of metaballs. Inside out implies that rather than viewing the structure from the outside, you view it from the inside.

Displacement mapping is slightly similar to bump mapping (which uses texturing info to modify the surface normal, faking a "bumpy" effect). However, displacement mapping actually does modify the surface to create the bumps. A bump-mapped object may look bumpy, but it's silhouette will tell the true tale, and remain smooth. A displacement mapped object will appear bumpy, and will appear bumpy in silhouette as well.

So, you merge a bunch of inside-out metaballs of varying sizes, and displacement map the inside surface of the metaballs with noise to create a bumpy, uneven effect. Add some texture coloration, a few dim lights for that all-important gloomy effect, and you have tunnels.

Man, that got my curiosity up. I might have to tinker with that some.

EDIT: Also, I don't know about Milkshape etc... but I use Blender, which has metaball primitives if you are interested in playing around with them to see how they work. Be warned: they are extremely fun, and it is easy to waste a considerable amount of time just playing with them.

Josh
vertexnormal AT linuxmail DOT org

Check out Golem: Lands of Shadow, an isometrically rendered hack-and-slash inspired equally by Nethack and Diablo.

[edited by - VertexNormal on November 16, 2003 1:25:05 PM]

My method for doing nice natural looking caves and passageways is to start with a regular hex/triangles grid and play with vertexes A LOT to add soft edges to the "corridors" and generally break the square feeling that a normal tunnel would have.
Working with triangles (or Wedges as they call it in Worldcraft) is the best way to get started although you ll quickly realize the hassle of having non lit faces and sticky polygons.
I suggest you start by having an uneven ground with straight walls (that is, the walls would be projected straight from the ground).
With an hex based path, varying ground level, and possibly varying ceiling, you have something nice to get started.
Then you can start playing with sloped walls... but that''s a different level, I assure you.

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You can make very good looking natural underground tunnels by using a pipe, appling noise to it and an approprite texture.
You have the camera inside the pipe and it all looks very nice I remeber seeing an anamition a while back that added water to bottom of the pipe by placing it in a cube. The animation consited of a raft traviling floating down the looped tunnel it was very nice.

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maybe if he tells us what he wants to do the tunnels for ?
If it''s prerendered graphics, my technique obviously wont be good enough.
But for an engine like Halflife (he mentioned WorldCraft) it really made wonders with the right textures and lights (I love playing with lighting).

Any more details Lythic ? Or are you already happy with the answers ?

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