This mod offers components that run LUA code and interface with each other through a global environment. It makes complex automated railway systems possible.
### atlatc
The mod is sometimes abbreviated as 'atlatc'. This stands for AdvTrainsLuaATC. This short name has been chosen for user convenience, since the name of this mod ('advtrains_luaautomation') is very long.
### Privilege
To perform any operations using this mod (except executing operation panels), players need the "atlatc" privilege.
This privilege should never be granted to anyone except trusted administrators. Even though the LUA environment is sandboxed, it is still possible to DoS the server by coding infinite loops or requesting expotentially growing interrupts.
### Active and passive
Active components are these who have LUA code running in them. They are triggered on specific events. Passive components are dumb, they only have a state and can be set to another state, they can't perform actions themselves.
### Environments
Each active component is assigned to an environment. This is where all data are held. Components in different environments can't inferface with each other.
This system allows multiple independent automation systems to run simultaneously without polluting each other's environment.
/env_create <env_name>
Create environment with the given name. To be able to do anything, you first need to create an environment. Choose the name wisely, you can't change it afterwards.
/env_setup <env_name>
Invoke the form to edit the environment's initialization code. For more information, see the section on active components. You can also delete an environment from here.
### Active components
The code of every active component is run on specific events which are explained soon. When run, every variable written that is not local and is no function or userdata is saved over code re-runs and over server restarts. Additionally, the following global variables are defined:
# event
The variable 'event' contains a table with information on the current event. How this table can look is explained below.
# S
The variable 'S' contains a table which is shared between all components of the environment. Its contents are persistent over server restarts. May not contain functions, every other value is allowed.
Example:
Component 1: S.stuff="foo"
Component 2: print(S.stuff)
-> foo
# F
The variable 'F' also contains a table which is shared between all components of the environment. Its contents are discarded on server shutdown or when the init code gets re-run. Every data type is allowed, even functions.
The purpose of this table is not to save data, but to provide static value and function definitions. The table should be populated by the init code.
# Standard Lua functions
The following standard Lua libraries are available:
string, math, table, os
The following standard Lua functions are available:
Cause LuaAutomation to trigger an 'int' event on this component after the given time in seconds with the specified 'message' field. 'message' can be of any Lua data type.
Not available in init code!
interrupt_pos(pos, message)
Immediately trigger an 'ext_int' event on the active component at position pos. 'message' is like in interrupt().
USE WITH CARE, or better don't use! Incorrect use can result in expotential growth of interrupts.
The event table is a table of the following format:
{
type = "<type>",
<type> = true,
... additional content ...
}
You can check for the event type by either using
if event.type == "wanted" then ...do stuff... end
or
if event.wanted then ...do stuff... end
(if 'wanted' is the event type to check for)
# Init code
The initialization code is not a component as such, but rather a part of the whole environment. It can (and should) be used to make definitions that other components can refer to.
Examples:
A function to define behavior for trains in subway stations:
function F.station()
if event.train then atc_send("B0WOL") end
if event.int and event.message="depart" then atc_send("OCD1SM") end
The init code is run whenever the F table needs to be refilled with data. This is the case on server startup and whenever the init code is changed and you choose to run it.
Functions are run in the environment of the currently active node, regardless of where they were defined. So, the 'event' table always reflects the state of the calling node.
The 'event' table of the init code is always {type="init", init=true}.
# ATC rails
The Lua-controlled ATC rails are the only components that can actually interface with trains. The following event types are generated:
The LuaATC interface provides a way to hook into the approach callback system, which is for example used in the TSR rails (provided by advtrains_interlocking) or the station tracks (provided by advtrains_lines). However, for compatibility reasons, this behavior needs to be explicitly enabled.
Enabling the receiving of approach events works by setting a variable in the local environment of the ATC rail, by inserting the following code:
__approach_callback_mode = 1
-- to receive approach callbacks only in arrow direction
-- or alternatively
__approach_callback_mode = 2
-- to receive approach callbacks in both directions
The following event will be emitted when a train approaches:
{type="approach", approach=true, id="<train_id>"}
Please note these important considerations when using approach callbacks:
- Approach events might be generated multiple times for the same approaching train. If you are using atc_set_lzb_tsr(), you need to call this function on every run of the approach callback, even if you issued it before for the same train.
- A reference to the train is available while executing this event, so that functions such as atc_send() or atc_set_text_outside() can be called. On any consecutive interrupts, that reference will no longer be available until the train enters the track ("train" event)
- Unlike all other callbacks, approach callbacks are executed synchronous during the train step. This may cause unexpected side effects when performing certain actions (such as switching turnouts, setting signals/routes) from inside such a callback. I strongly encourage you to only run things that are absolutely necessary at this point in time, and defer anything else to an interrupt(). Be aware that certain things might trigger unexpected behavior.
Operations that are safe to execute in approach callbacks:
- anything related only to the global environment (setting things in S)
- digiline_send()
- atc_set_text_*()
- atc_set_lzb_tsr() (see below)
In the context of approach callbacks, one more function is available:
atc_set_lzb_tsr(speed)
Impose a Temporary Speed Restriction at the location of this rail, making the train pass this rail at the specified speed. (Causes the same behavior as the TSR rail)
The event fired is {type="punch", punch=true} by default. In case of an interrupt or a digiline message, the events are similar to the ones of the ATC rail.
