Abstract
========

Proof of concept for underwater tunnels in GTASA by stacking water.dat areas.


Explanation
===========

See "stacked-water-diagram.jpg" to see how it works.

The "water.dat" file has a comment at the end of each line used for setting up the tunnel's water stack. "water.dat" seems very sensitive about commenting, so beware if you try adding your own.

The tunnel is created by repeating a tube ParoXum made.


Installation
============

1. Add my files (actually made by ParoXum) from the "ADD_TO_migeneric-img" folder to your MISA "models\migeneric.img" archive.
2. Copy my "maps\tunnels\" folder, including the files it contains, to your MISA "data\maps\" folder.
3. Copy my "data\gta.dat" file to replace your MISA "data\gta.dat" file. Or, just copy the IDE and IPL line for the tunnel IDE and IPL files.
4. Run MISA.


Testing it Yourself
===================

Drive in Tunnels Underwater
---------------------------

Access the freeway tunnel from the rightmost quay at DieselGT's docks in North East illCOM. Drive North and eventually you come out inside the cliffs on the North coast of illURB.

The left-hand lane is used for showing you a cross-section of the water layers. I've made the bottom layer's surface visible to help with testing.

Use either side of the road once you've gotten beneath the bottom layer of water. You'll be able to see it just inside the ceiling of the tunnel at the top of each hump further on. This is to aid testing; the bottom layer wouldn't be visible and there would be no water inside tunnels if we did this for real.

Swim in Ocean inside Tunnel
---------------------------

Use the left quay at DieselGT's docks. Walk or jump onto the surface of water at the top of the right lanes. Dive and then swim downwards all the way through to the bottom layer of water (its surface is visible).

Keep going and you'll fall out the bottom of the water, into a non-water environment...even though there's a layer of normal ocean above you. :)

Swim in Ocean above Tunnels
---------------------------

For a more "natural" test of swimming, drive on the MISA surface roads to the South beach of illURB, opposite the two quays of DieselGT's docks. There is a narrow strip of water which overlaps one half of each tunnel.

Run into this water and swim out until the sea bed is flat. Dive down to it and you'll be able to reach it normally. If you swim further towards the quays, you can swim past the sea bed level, turn East and fall onto the tunnel roof to illURB. From here you can experiment with jumping into the side of the water.

When jumping into the side of the water it is not perfectly continuous. However, this can only happen when there's an accidental gap in the landscape. The solution is to fill these in, so the player can only enter the sea via its surface, and everything works fine.


Feedback
========

Discuss in this topic:
http://www.gtaforums.com/index.php?showtopic=258362


Credits
=======

This is based on the work of many other people. Especially Paroxum, Steve-M, GForce and some others.

Creator: Ben 'Cerbera' Millard
History: 2006-11-29 -> 2006-11-29