JCM:Scripting/Utilities

Utilities

As the scripting functionality is based on the Nemo Transit Expansion, a number of helper classes are inherited from NTE to provide informations or to simplify code implementation.

Printing debug information

static print(params: Object...): void

This function outputs a message to the Minecraft log (the message is not displayed in the game). Any number of arguments of any type can be passed to the function.

Versions

Functions are provided where you can get the version number to ensure compatibility with different versions of mods (if any).

Functions	Description
static Resources.getAddonVersion(modId: string): string	Obtain the version of a mod that is hooked to the scripting functionality. Out of the box in JCM, the possible modId are: mtr jcm

TextUtil

MTR uses the station naming format Name in one language|Name in another language||EXTRA, so TextUtil is implemented to provide functions to separate these parts.

Functions	Description
static TextUtil.cycleString(src: String): String	Returns a text that cycles different languages. (Delimited by the pipe | character)
static TextUtil.cycleString(src: String, duration: int): String	Returns a text that cycles different languages. (Delimited by the pipe | character) The cycle frequency is decided by the duration parameter, in Minecraft Tick.
static TextUtil.getCjkParts(src: String): String	Returns the CJK parts of the passed string.
static TextUtil.getNonCjkParts(src: String): String	Returns the non-CJK parts of the passed string.
static TextUtil.getExtraParts(src: String): String	Returns the extra part of the passed string.
static TextUtil.getNonExtraParts(src: String): String	Returns everything except the extra part.
static TextUtil.getNonCjkAndExtraParts(src: String): String	Returns everything except the CJK parts.
static TextUtil.isCjk(src: String): boolean	Checks whether the string contains CJK characters.

Timing

Functions	Description
static Timing.elapsed(): double	Returns the running time of the game in seconds. It is constantly increasing, even when the game is paused.
static Timing.delta(): double	The time difference between the current render call and the previous one. This can be used, for example, to calculate the angle by which the wheel have turned during the elapsed time.

StateTracker

Sometimes it is necessary to take transition states into account. For example, to play an animation only once when a certain condition is reached (because if (…distance < 300) ctx.play… would be satisfied every frame after the condition was met, and then play every frame after that, which would result in hundreds of animations), or to play an animation in the first second after a page switch.

Since each object should have its own tracker, you would probably want to store it in the script's state variable.

Functions	Description
new StateTracker()	Creates StateTracker.
StateTracker.setState(value: string): void	Sets the new state.
StateTracker.stateNow(): string	Returns the current state.
StateTracker.stateLast(): string?	Returns the previous state. If it does not exist, null is returned.
StateTracker.stateNowDuration(): double	Returns the amount of time the current state lasts.
StateTracker.stateNowFirst(): boolean	Was the state just changed by the setState function in this loop or not?

CycleTracker

This is a StateTracker that automatically switches on a cyclic basis by time.

Since each object should have its own tracker, you would probably want to store it in the script's state variable.

Functions	Description
new CycleTracker(params: Object[])	Creates a CycleTracker. The parameters are the states it will switch through and the duration of each state in seconds. Example: new CycleTracker([“route”, 5, “nextStation”, 5]).
CycleTracker.tick(): void	Updates the status based on the current time.
CycleTracker.stateNow(): string	Returns the current state.
CycleTracker.stateLast(): string?	Returns the previous state. If it does not exist, null is returned.
CycleTracker.stateNowDuration(): double	Returns the amount of time the current state lasts.
CycleTracker.stateNowFirst(): boolean	Was the state just changed by the setState function in this loop or not?

RateLimit

Some tasks do not require too frequent execution, for example, the display may not be updated every frame, but only 10 times per second. Therefore, you can limit the frequency of their execution to improve performance.

Since each object should have its own tracker, you would probably want to store it in the script's state variable.

Functions	Description
new RateLimit(params: Object[])	Creates a RateLimit. interval is the interval in seconds between two triggers, for example, an interval of 0.1 means it should occur ten times per second.
RateLimit.shouldUpdate(): boolean	Has enough time elapsed between the last triggers? Wrap the necessary code using if (state.rateLimitXXX.shouldUpdate()) { … } to limit its execution frequency.
RateLimit.resetCoolDown(): void	Resets the timer to go off as soon as possible.

MTRClientData

Client data from MTR that can be used to read routes, transfers, etc. See the source code of MinecraftClientData.java from MTR.

MinecraftClient

Due to obfuscation, there is no way to directly provide a client class for use. Therefore, several helper methods are created:

Functions	Description
static MinecraftClient.worldIsRaining(): boolean	Is it raining in the world?
static MinecraftClient.worldIsThundering(): boolean	Is it thundering in the world?
static MinecraftClient.worldIsRainingAt(pos: Vector3f): boolean	Is it raining and getting wet in a given chunk?
static MinecraftClient.worldDayTime(): int	Returns the in-game world time in ticks.
static MinecraftClient.narrate(message: string): void	This calls the Minecraft narrator to narrate the message.
static MinecraftClient.displayMessage(message: String, actionBar: boolean): void	This displays the message as an in-game chat message. If action bar is true, it will display on the action bar instead. (Above inventory hotbar)

HttpUtil

HttpUtil allows scripts to send HTTP requests to the internet, allowing scripts to fetch plain text content/image over the internet.

Calling any function within this class will return a NetworkResponse, which is described below.

If the HTTP request fails, an error will be thrown. Consider using try/catch block to handle script errors. (This behaviour may change in the future!)

Functions	Description
static HttpUtil.fetchString(url: string): NetworkResponse<String>	Fetch plain text content from the corresponding URL
static HttpUtil.fetchString(url: string, requestOption: RequestOption): NetworkResponse<String>	Fetch plain text content from the corresponding URL, with the request option applied. (See below for RequestOption)
static HttpUtil.fetchImage(url: string): NetworkResponse<BufferedImage>	Fetch image from the corresponding URL
static HttpUtil.fetchImage(url: string, requestOption: RequestOption): NetworkResponse<BufferedImage>	Fetch image from the corresponding URL, with the request option applied. (See below for RequestOption)

RequestOption

This is a JavaScript Object that specifies connection-related details.

Field Name	Type	Description
method	string	The HTTP method used. Default to GET
connectionTimeout	number	Specify the max timeout in millisecond when sending the HTTP request.
readTimeout	number	Specify the max timeout in millisecond when retrieving data from an HTTP request.
headers	object	A JavaScript object which contains the HTTP header to apply when sending the request.
body	string	The request body to send. This is typically used for HTTP POST request. Note: The Content-Length header will be automatically set if this field is supplied.

NetworkResponse

Functions	Description
NetworkResponse.getResponseCode(): int	Get the HTTP Response Code, a list can be found here.
NetworkResponse.getData(): ?	Obtain the fetched data. This could be either a string, or an AWT BufferedImage depending on what function you invoke in HttpUtil.
NetworkResponse.getHeaders(): Map<String, List<String>>	Obtain the headers in the HTTP response

Example

TODO

Further Note

HttpUtil currently always overrides the User-Agent header to Joban Client Mod (https://joban.org/jcm).