Modular Tunnel Boring Machine, aka
				  The Almighty Digtron
				  ====================

This mod contains a set of nodes that can be used to construct highly customizable and modular tunnel-boring machines, bridge-builders, road-pavers, wall-o-matics, and other such construction/destruction contraptions.

The basic nodes that can be assembled into a functioning digging machine are:

* Digger heads, which excavate material in front of them when the machine is triggered
* Builder heads, which build a user-configured node in front of them
* Inventory modules, which hold material produced by the digger and provide material to the builders
* Control node, used to trigger the machine and move it in a particular direction.

A digging machine's components must be connected to the control node via a path leading through the faces of the nodes - diagonal connections across edges and corners don't count.

Important general concepts
--------------------------

Several general concepts are important when building more sophisticated diggers.

* Facing - a number between 0-23 that determines which direction a node is facing and what orientation it has. Not all nodes make use of facing (basic blocks such as cobble or sand have no facing, for example) so it's not always necessary to set this when configuring a builder head. The facing of already-placed nodes can be altered through the use of the screwdriver tool.

* Period - Builder and digger heads can be made periodic by changing the period value to something other than 1. This determines how frequently they trigger. A period of 1 triggers on every node, a period of 2 triggers once every second node, a period of 3 triggers once every third node, etc. These are useful when setting up a machine to place regularly-spaced features as it goes. For example, you could have a builder head that places a torch every 8 steps, or a digger node that punches a landing in the side of a vertical stairwell at every level.

* Offset - The location at which a periodic module triggers is globally uniform. This is handy if you want to line up the nodes you're building (for example, placing pillars and a crosspiece every 4 nodes in a tunnel, or punching alcoves in a wall to place glass windows). If you wish to change how the pattern lines up, modify the "offset" setting.

Note that offset and period are calculated from the location of the *controller* node, which is shared across the whole array of modules, so it's not necessary to line up all of your builder heads in the same row or column.

* Shift-right-clicking - since most of the nodes of the digging machine have control screens associated with right-clicking, building additional nodes on top of them or rotating them with the screwdriver requires the shift key to be held down when right-clicking on them.

Detailed module guide
=====================

Control Module
--------------

Right-click on this module to make the digging machine go. The digging machine will go in the direction that the control module is oriented, so in theory you could adjust the digging machine's position by reoriented the control module (or building additional ones) and nudging it to the side.

A control module can only trigger once per second. Gives you time to enjoy the scenery and smell the flowers (or their mulched remains, at any rate).

If you're standing within the digging machine's volume, or in a node adjacent to it, you will be pulled along with the machine when it moves.

Pusher Module
-------------

Aka the "can you rebuild it six inches to the left" module. This is a much simplified control module that does not trigger the digger or builder heads when right-clicked, it only moves the digging machine. It's up to you to ensure there's space for it to move into.

Digger Head
-----------

Facing of a digger head is significant; it will excavate material from the node on the spinning grinder wheel face of the digger head. Generally speaking, you'll want these to face forward - though having them aimed to the sides can also be useful.

Digger heads can have a period and offset defined if you want them to punch regularly-spaced holes. Note that diggers aimed forward should generally always have a period of 1, otherwise the digging machine may be unable to move.

Sand Digger Head
----------------

This specialized digger head is designed to excavate only loose material such as sand or gravel. It has no period/offset settings; it will always attempt to dig sand when it's present in its target node. It leaves all other types of nodes alone. (in technical terms, this digger digs nodes belonging to the "falling_node" group)

The intended purpose of this digger is to be aimed at the ceiling or walls of a tunnel being dug, making spaces to allow shoring nodes to be inserted into unstable roofs but leaving the wall alone if it's composed of a more stable material.

Builder Head
------------

A builder head is the most complex component of this system. It has period and offset properties, and also an inventory slot where you "program" it by placing an example of the node type that you want it to build. Only a single item is needed here, any additional items in this inventory stack will be shunted into the digger's general inventory (or ejected from the control node if there's no space for it).

Builders also have a "facing" setting. If you haven't memorized the meaning of the 24 facing values yet, builder heads have a helpful "Read & Save" button to fill this value in for you. Simply build a temporary instance of the node in the output location in front of the builder, adjust it to the orientation you want using the screwdriver tool, and then when you click the "Read & Save" button the node's facing will be read and saved.

Inventory Module
----------------

Inventory modules have the same capacity as a chest. They're used both for storing the products of the digger heads and as the source of materials used by the builder heads. A digging machine whose builder heads are laying down cobble can automatically self-replenish in this way, but note that an inventory module is still required as buffer space even if the digger heads produced everything needed by the builder heads in a given cycle.

Inventory modules are not required for a digging-only machine. If there's not enough storage space to hold the materials produced by the digging heads, the excess material will be ejected out the back of the control node. They're handy for accumulating ores and other building materials, though.

Digging machines can have multiple inventory modules added to expand their capacity.

Structural Module
-----------------

These nodes allow otherwise-disconnected sections of builder machines to be linked together. You can also use them to build a platform to stand on as you ride your mighty mechanical leviathan through the landscape.

Digtron Lamp
------------

A light source that moves along with the digging machine. Convenient if you're digging a tunnel that you don't intend to outfit with torches or other permanent light fixtures. Not quite as bright as a torch since the protective lens tends to get grimy while burrowing through the earth.

What Do These Noises Mean?
==========================

When a digging machine is unable to complete a cycle it will make one of several noises to indicate what the problem is.

Squealing traction wheels indicates a mobility problem. If the squealing is accompanied by a buzzer, the digging machine has encountered an obstruction it can't dig through. This could be a protected region (the digging machine has only the priviledges of the player triggering it), a chest containing items, or perhaps the digger was incorrectly designed and can't dug the correctly sized and shaped cavity for it to move forward into. There are many possibilities.

Squealing traction wheels with no accompanying buzzer indicates that the digging machine has no solid adjacent nodes to push off of. Tunnel boring machines cannot fly or swim, not even through lava, and they don't dig fast enough to "catch sick air" when they emerge from a cliffside. If you wish to cross a chasm you'll need to ensure that there are builder heads placing a solid surface as you go.

A ringing bell indicates that there are insufficient materials in inventory to supply all the builder heads for this cycle.

A short high-pitched honk means that one or more of the builder heads don't have an item set. A common oversight, especially with large and elaborate digging machines, that might be hard to notice and annoying to fix if not noticed right away.

Crafting recipes
================

All machine nodes are constructed from a "Digtron Core" craft item and other materials.

Digtron cores are made with the following recipe:

[     ,     steel    ,      ]
[steel, mese fragment, steel]
[     ,     steel    ,      ]
			
Digger heads:

[       , diamond ,        ]
[diamond,  core   , diamond]
[       , diamond ,        ]

Sand/gravel digger heads:

[     , steel ,      ]
[steel, core  , steel]
[     , steel ,      ]

Builder heads:

[             , mese fragment,              ]
[mese fragment,     core     , mese fragment]
[             , mese fragment,              ]

Controller heads:
		
[            , mese crystal,             ]
[mese crystal,     core    , mese crystal]
[            , mese crystal,             ]

Inventory modules:

[chest,]
[core,]
	
Structural modules:

[stick,      , stick]
[     , core ,      ]
[stick,      , stick]

Lantern module:

[torch,]
[core,]
	
Pusher controller:

[    , coal ,     ]
[coal, core , coal]
[    , coal ,     ]