Scripting blocks

As a developer when you put a programming language inside your program its a good sign you’ve gone off the deep end. That is what I have done. I’m now going to try to justify why I’ve done this in an attempt to lie to myself that it was a good idea.

Scripting blocks are a response to wiring getting too complicated and ugly and look like this:

script block

The idea is that they can accept a small text program and replace a huge load of wiring with just a little bit of text. So they can convert something like this (which is an automated turret that tracks and fires at the player):

TurretComplicated

Into something like this:

TurretSimple

This turret is actually something I intend to exist within spawned structures so I wanted the scripting block for my own use but I’m putting it as a general block for advanced players to use (see, justification).

Here’s a video of how its used:

The scripting block is available in the most recent version of One Million Worlds (version 0.4.3 onward)

So, that’s that done. Now its time for the documentation! Yay!

Instructions

Once you’ve placed a script block look at it and press e to open up the script.

Inputs and outputs

The inputs and outputs are all referred to by the letters N,S,E,W,U,D for north, south, east, west, up and down. The N,S,E,W are shown on the chip itself, the up and down you’ll just have to figure out for yourself.

You can set a direction equal to a value and that value will be output to that directions. e.g.

N = 5

or

W = 'Hi there'

You can output to multiple directions in a single program

N = 5
W = 'Hi there'

You refer to the inputs in the same way, so say you have a number inputted in the West port and wanted North to be twice the West value you could use the following script

N = 2 * W //note that * means multiply

// indicates a comment, the rest of the line is ignored, so you can add notes to your script

Implicit outputs

If you only have one output equal to a simple equation (or want all your outputs to be the same) you can omit specifying what output you want the value to go to, so you can simplify the previous program to this:

2 * W //all outputs will receive a value twice the size of WEST

Asking questions

You can use the “if” keyword (and a whole bunch of brackets!) to do different things based on a question. So lets say you have an input W that is the distance away a player is (reported by a scanner block) and if the player is closer than 5 meters away you want to show on a screen (connected to N) “Go away” and raise a door (a Rail block connected to S) but if they do go away reopen the door you could use this program:

if(W<5){        // W is the distance away the player is
  N = 'Go away!'
  S = 4         //S is connected to a rail set to position mode, 4 is fully closed
}else{
  S = 1         //position 1 is fully open   
}

Variables

Sometimes you want to calculate something once and then use it several times, you can store it in a variable

someComplicatedCalculation= 2 * N + S
W = someComplicatedCalculation
E = 2 * someComplicatedCalculation

Arrays

Sometimes a piece of data has several parts, like a position might have an x, y and z. These can be both read and creating within scripts. The main place you’ll see these is inputs coming from scanner blocks which report positions as an array of 3 numbers. For arrays that enter on inputs you can refer to them in 2 ways:

As x,y,z:

distanceAway = N.x      //N.x is the first value in the array, N.y is the second, N.z is the third
S = distanceAway

This way of referring to arrays only works with arrays entering on inputs, not ones you create yourself.

As a number:

distanceAway = N[0]      //N[0] is the first value in the array, N[1] is the second, N[2] is the third
S = distanceAway

Note that the first value is N[0], not N[1], arrays start at zero. 

You can create arrays using square brackets. for example this program would return an array of the numbers 1,2,3

N = [1,2,3]

You can of course use variables

distanceAway = N.x 
N = [distanceAway, 2*distanceAway, 3*distanceAway]

Inbuilt information

Some data is provided in variables for use in your script. At present these are:

  • firstRun – if this is the first time this script has run (i.e. you just edited it) this is true, otherwise its false
  • timeSlice – how much time this run of the script represents (aka how long there is between runs of the script)
  • scriptTime – the total time this script has run (its the sum of all the timeSlices since the script was changed)

Remembering things from the last time the script was run

Usually the script runs a fresh each time, forgetting all its variables, but it is possible to remember things from run to run, this is done using the persistent (or p) scope. Also because I really struggle to spell persistent you can also use the persistant scope and that will work fine. Anything in the persistent scope will still be available the next time the script runs.

So lets say we want to modify the “go away” script from the “asking questions” section so that if starts saying go away if you come within 5 meters but then it keeps saying it until you are 10 meters away:

if(firstRun){
    p.goAway = false //when the script first starts up default to not saying anything
}

if(W<5){     p.goAway = true } if(W>10){
    p.goAway = false
}
//note that if W is between 5 and 10 it is left at whatever value it had previously

if(p.goAway){
    N = 'Go away!'
}

Inbuilt functions

I’ll be creating inbuilt functions as I need them (I’m selfish like that) for now these are available:

  • clamp – This will take a value and ensure it remains between two other values
N=clamp(W,5,10) //This will output the value of W, or 5 if W is below 5, or 10 if W is above 10
  • stabilise – This will provide functionality to stabilise a system, e.g. if you have a turret that’s looking at the player controlling a rotator block to make it look directly at the player…… its best explained by watching the above video. It is a PID controller that is used like:
stabilise(errorValue, proportionalTerm, integralTerm, derivitiveTerm)

The meaning of the terms are as follows:

errorValue –  how far the recorded value is from what you want it to be. E.g. if the player is 30 degrees to the left and you want to be looking at them the errorvalue is 30.
proportionalTerm – this is a tuning parameter, you need to play with it to see what works. You want to set it to a value such that your system swings quickly to the desired position (even if it overshoots)
intergralTerm – this is a tuning parameter, you need to play with it to see what works (you’ll probably want it to be zero. You can use it if you need to apply some force even if you are at the correct position (e.g. when you hold a weight up with your arm you still need to apply force even when you’re in the right position
derivitiveTerm –  this is a tuning parameter, you need to play with it to see what works. This controls overshoot, if the system keeps osculating about a set point increase the derivitiveTerm.

Loops

You don’t need loops, please skip this section.

Ok fine, loops are useful when you want to do something more than once.

A simple loop could be like this:

for(i = 0; i<5; i++){
   /*this area will be executed 5 times, 
   once with i as 0, then 1 etc until finally when i is 4*/
}

Lets say, in the “go away” example the closer they get the more you want to say go away, lets say one exclamation mark for every meter they get towards you. A loop can do that.

distanceAway = W
permittedDistance = 10
if(distanceAway < permittedDistance){
    message = "Go Away"
    exclamationMarksToShow = permittedDistance - distanceAway //closer they get the more exclamation marks

    for( i = 0; i < exclamationMarksToShow; i++){
        message = message + "!"
    }
    N = message
}

Reading errors

If any problems occur with your script the errors are shown when you next open the script panel (note it doesn’t refresh until you open and close it). It will tell you the line number and letter number where it knew for sure that your script was wrong, its possible it went wrong before this but that’s its best guess at where it went wrong

Secretly its JavaScript

The script used within OneMillionWorlds is actually a variant of JavaScript. I’ve made some additions but broadly if your script is valid javascript it will work. I haven’t covered anywhere near the full features of the language so if you’ve got to this point and want more there are may resources for javascript available online.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s