KLE (KSH Lane Effector) is a program made by JiminP (@123jimin) to simplify adding lane visual effects to .ksh charts.
Currently this program uses JavaScript's eval to evaluate expressions, and ; import command can import any file in the system.
While there is a simple filter to only allow simple expressions before doing an eval, it might be possible to exploit this eval to execute arbitrary scripts.
Therefore, before executing a KLE script, examine it (and maybe .ksh too!) to make sure that no spooky thing is going on.
Once the project becomes serious, usage of eval will be removed and arbitrary ; import will be disabled (except for stdlib and scripts in same folder),
but for now, be careful on these possible security problems.
A KLE script consists of various 'command's, which modifiy zoom values of a chart. Commands have arguments, which can be used to modify their behavior
A command can be used in a .ksh chart like the example shown below.
In this example, name-of-command command will be execued, and three arguments {1/4}, 12, 34 will be provided.
...
0000|00|--
--
;name-of-command {1/4} 12 34
0000|00|--
0000|00|--
...
The first argument of the command is always the length of the region which the command will be applied.
Lengths are represented in terms of amount of 192nd notes or in beats like {3/8} (three 8th notes in this case).
This is all you can do in a .ksh chart. You need to define commands in a .kle script file, then give them to the KLE program.
The KLE program can be executed like this: node bin.js in.ksh out.ksh -k script.kle.
When this is executed, script.kle will be applied on in.ksh, which will create out.ksh.
It is recommended not to include any notes (especially lasers) in in.ksh, since parsing .ksh files are not yet stable.
The ksh chart can be exported to a Lua script describing the chart, by specifying -l flag like this: node bin.js in.ksh out.ksh -l chart.lua.
Every command definitions begin with a line ;command name-of-command $length $arg1 $arg2 ..., and end with a line ;end command.
The following code is an example of a command definition:
;command flick $length $amount=50
zoom_side = 0 $amount
@
zoom_side = $amount/2
@
zoom_side = $amount/4
@
zoom_side = $amount/8
@
zoom_side = 0
@
@
;end command
@ (or you may use 0000|00|--) is used to represent a chart line. Since there are six @s in the flick command, a @ represent sixth of $length.
As you can see, every variable begin with a dollar sign. Also, you can specify default values for arguments like $amount=50.
You can include other commands in a command definition like this:
;command flick-left $length $amount
;flick $length -$amount
;end command
When using other commands, you can use expressions to compute values. However, be careful not to include spaces in expressions. Spaces are used to separate arguments.
If you wish to include spaces because of readability, you can wrap arguments in parentheses.
;flick $length ($amount*2 + $length/10)
zoom_side, zoom_top, and zoom_bottom are pre-defined commands which modify relative zoom values, so you can use it like ; zoom_side 50
to increase the side zoom value by 50, or ; zoom_side 0 100 to make a sudden zoom change.
However, these three are very special since you can also use it in a more conventional way: zoom_side = 0 100.
Here's an another example for a command where stdlib easeout and easein commands are used:
// You can use comments like this.
// Imports the standard library (explained below)
;import stdlib
;command bounce $length $amount
// Initial relative zoom values are zero.
zoom_bottom = 0
zoom_top = 0
// Gives an 'ease-out' effect...
// (Lanes zoom rapidly at first then moves slower)
;easeout_bottom $length/2 $amount
;easeout_top $length/2 $amount
@
// Zoom values achieve maximum values.
zoom_bottom = $amount
zoom_top = $amount
// Gives an 'ease-in' effect...
// (Opposite of ease-out)
;easein_bottom $length/2 -$amount
;easein_top $length/2 -$amount
@
// Final relative zoom values are zero again.
zoom_bottom = 0
zoom_top = 0
;end command
In KLE, calls to commands in a command is not processed immediately. Instead, following steps happen when a command is being executed.
- Statements in a command are processed.
- While executing statements, calls to other commands are stored in a list.
- After all statements are executed, zoom values are applied on a chart.
- Timing is computed using # of lines being encountered and the first argument
$length.
- After zoom values are applied, stored commands in the list are executed one by one.
Currently there is a significant constraint for every command: every zoom values are relative, and they begin and end with 0!
If a script does not satisfy this constraint, then sudden zoom changes will automatically be added.
Therefore, "global" changes are impossible with commands; you must specify them by manually editing zoom values in a .ksh chart.
However, even with this constraint, a lot of interesting effects can be achieved.
Some statements are available for use. These can be used to make more complex commands.
;set sets the value of a variable.
A value of a variable can either be a number or a label.
For example, the following code prints 42 hello:
;set $foo 42
;set $bar hello
;print $foo $bar
To make KLE Turing-complete, KLE provides a branch statement.
;if $foo%4==0
;print Hello
;else if $foo%4==1
;print Bye
;else
;print Wow
;end if
;repeat N ... ;end repeat repeats given statements for a given time.
;repeat A B is identical to ;repeat B/A, but emits an error if B is not divisible by A.
This is an implementation of FizzBuzz in KLE.
;set $i 1
;repeat 100
;if ($i % 15 == 0)
;print FizzBuzz
;else if ($i % 3 == 0)
;print Fizz
;else if ($i % 5 == 0)
;print Buzz
;else
;print $i
;end if
;set $i $i+1
;end repeat
;while (exp) ... ;end while repeats while (exp) evaluates to true.
;call $a $b executes a command whose name is stored in $a.
This is not a pre-defined command but a statement.
If this were a command, then lines like ;call zoom_top 10 would be useless, because every zoom values in a command must begin and end with 0.
;line is identical to @ or 0000|00|--.
Actually latter two are aliases to the ;line statement.
;process on or ;process off turns on/off processing KLE commands.
These are useful for quick developement of a chart.
This command only works when written in a .ksh chart file.
Using ;import stdlib, you can import the standard library to your script.
The standard library contains many useful effects.
;easein_bottom $length $amount
;easein_top $length $amount
;easein_side $length $amount
;easeout_bottom $length $amount
;easeout_top $length $amount
;easeout_side $length $amount
These commands can be used to convert a linear transition into ease-in or ease-out transition.
Example:
Following portion of a .ksh chart gives an ease-in effect for zoom_top from 40 to 100,
while ease-out effect will be given for zoom_bottom from 50 to 0.
--
t=4/4
zoom_top=40
zoom_bottom=50
;easein_top {4/4} 60
;easeout_bottom {4/4} -50
0000|00|--
zoom_top=100
zoom_bottom=0
--
Other than zoom_* commands, there are few other pre-defined commands.
;import a.kle imports commands from a.kle KLE script.
;import stdlib always import the standard library.
;print foo prints foo with a timestamp (# of ticks from the beginning of the chart).
;error foo prints foo then throws an error.
;null does nothing. It's a boring command, so do not use it.