labels

Label and Game Step

Visual Novels are usually a succession of screenshots with images and text.

In Pixi’VN, you can manage this succession of screens with the "steps". The steps they are functions that are executed every time the Next Step function is called. In these steps you can add images, dialogues etc...

The labels are containers of steps, they are used to organize the steps in a more readable way.

Basically the idea of the life cycle of the game is which is started at the beginning a label and is executed the first step of the label. After that, connecting the function Next Step to a event (like a button click), every time the function is called, the next step of the label is executed. Some steps could start other labels. The game will end only when all the steps are completed.

Label

The label is a container of steps. It is used to organize the steps in a more readable way.

For create a label you must use the newLabel() function and pass:

the id of the label, must be unique
the steps of the label, an array of functions that will be executed in order. Or a function that returns the steps.

const START_LABEL_ID = "start_label_id"

export const startLabel = newLabel(START_LABEL_ID,
    [
        () => {
            setDialogue({ character: liam, text: "Example of dialogue" })
        },
        (props) => GameStepManager.jumpLabel(START_LABEL_ID, props),
    ]
)

Parameters of the label steps

You can pass a type to newLabel function for add other parameters in addition to StepLabelProps for all steps of the label.

const START_LABEL_ID = "start_label_id"

export const startLabel = newLabel<{name: string}>(START_LABEL_ID,
    [
        (props) => {
            console.log(props.name)
        },
    ]
)

GameStepManager.callLabel(startLabel, {
    // add StepLabelProps here
    navigate: navigate, // example
    // and the props that will be passed to the label
    name: "John"
})

All Steps Parameters

You can "override" the interface StepLabelProps to set required parameters for all steps of all labels.

// pixi-vn.types.ts
declare module '@drincs/pixi-vn/dist/override' {
    interface StepLabelProps {
        navigate: (route: string) => void,
    }
}

return GameStepManager.callLabel(TestLabel, {
    navigate: (route) => {
        // navigate to route
    }
})

All Steps Result

The steps can return a StepLabelResult object, by default the StepLabelResult object is a { [key: string]: any }.

You can "override" the interface StepLabelResult to set your custom properties in the result of the steps.

// pixi-vn.types.ts
declare module '@drincs/pixi-vn/dist/override' {
    interface StepLabelResult {
        newRoute?: string,
        [key: string]: any
    }
}

export const startLabel = newLabel(START_LABEL_ID,
    [
        () => {
            return {
                newRoute: '/new-route',
                customProperty: 12
            }
        },
    ]
)

Manage game flow with labels

The game flow is managed by functions that call labels, jump to labels, go back, close labels... These functions are in the GameStepManager object.

Run a label
Next Step and Go back
Close labels

Run a label

There are two ways to run a label:

Call a label
Jump to a label

Call a label

To call a label you must use the GameStepManager.callLabel function. This function have 2 parameters:

label: the label that will be called
props: the properties that will be passed to the label, if you not want to pass any parameter you can pass an empty object {}.

When you call a label, the steps of that label will be started. If before the call was running another label, the remaining steps of the another label will be executed after the steps of the called label.

For example if currently the game is running the step 5 of the label A and you call the label B, when all the steps of the label B are executed, the game will continue with the step 6 of the label A.

GameStepManager.callLabel returns a result of first step of the called label.

GameStepManager.callLabel(startLabel, {})

Remember that if you execute the GameStepManager.callLabel inside a step, you should return the result of first step of the called label.

export const startLabel = newLabel(START_LABEL_ID,
    [
        (props) => GameStepManager.callLabel(TestLabel, props),
        // not recommended but you can use this way:
        (props) => {
            return GameStepManager.callLabel(TestLabel, props).then((result) => {
                return result
            })
        },
    ]
)

Jump to a label

To jump to a label you must use the GameStepManager.jumpLabel function and pass the label. This function have 2 parameters:

label: the label that will be called
props: the properties that will be passed to the label, if you not want to pass any parameter you can pass an empty object {}.

When you jump to a label, the steps of the current label will be stopped and the steps of the label passed as parameter will be started.

For example if currently the game is running the step 5 of the label A, and call the label B, and you jump to the label C, when all the steps of the label C are executed, the game will continue with the step 6 of the label A. Because when you jump to the label C, the label B is closed.

GameStepManager.jumpLabel returns a result of first step of the called label.

GameStepManager.jumpLabel(startLabel, {})

Remember that if you execute the GameStepManager.jumpLabel inside a step, you should return the result of first step of the called label.

export const startLabel = newLabel(START_LABEL_ID,
    [
        (props) => GameStepManager.jumpLabel(TestLabel, props),
        // not recommended but you can use this way:
        (props) => {
            return GameStepManager.jumpLabel(TestLabel, props).then((result) => {
                return result
            })
        },
    ]
)

Next Step and Go back

Next Step

To execute the next step you must execute the GameStepManager.goNext() function. This function have a parameter props that will be passed to the next step, if you not want to pass any parameter you can pass an empty object {}.

GameStepManager.goNext({})

GameStepManager.goNext() is asynchronous, so, for example, you can use then for disabled a next button until the next step is executed.

// disable next button
GameStepManager.goNext({})
    .then((result) => {
        // enable next button
    })

Go back

Every step the system saves the current state of the game. To go back to the previous step you must execute the GameStepManager.goBack() function.

In parameters you must pass a function navigate: (path: string) => void that will be called with the URL Path or Route of the previous step, so you can use it to navigate to the previous Interface.

For exemple if you use a React Router Dom:

import { useNavigate } from 'react-router-dom';

const navigate = useNavigate();

if (GameStepManager.canGoBack) {
    GameStepManager.goBack(navigate).then(() => {
        // ...
    })
}

Close labels

Close current label

To close the current label you must execute the GameStepManager.closeCurrentLabel() function.

GameStepManager.closeCurrentLabel()

Close all labels

To close all labels you must execute the GameStepManager.closeAllLabels() function. If you call this function and after that you don't call any label, the game will block. After closing all labels you should call a label for manage the end of the game.

GameStepManager.closeAllLabels()

How to return different step lists based on a condition

When you create a new label you can pass a function that returns the steps of the label.

const START_LABEL_ID = "start_label_id"

export const startLabel = newLabel(START_LABEL_ID,
    () => {
        if (condition) {
            return [
                () => setDialogue({ character: liam, text: "Example of dialogue" }),
                (props) => GameStepManager.jumpLabel(START_LABEL_ID, props),
            ]
        } else {
            return [
                () => setDialogue({ character: liam, text: "Another example of dialogue" }),
                () => setDialogue({ character: liam, text: "Another example of dialogue 2" }),
                (props) => GameStepManager.jumpLabel(START_LABEL_ID, props),
            ]
        }
    }
)

How manage the end of the game

When all the steps of all labels are executed, the game will block. The developer must manage the end of the game. The reason is that ending management in visual novels can be handled in different ways:

The game ends when all the steps are executed
The game has no end, so if the steps are finished, there has been an error, and it needs to be handled
The game ends when the player reaches a certain point. For example, when the player reaches a certain point in the story you can navigate to a game over screen

The recommended method for managing the end of the game is to create a startLabel that will be the first label to be executed. This label will be responsible for calling the other labels. startLabel for manage the end must have a how last step a function that will be responsible for ending the game.

For example, if you want to end the game when the steps are finished:

const START_LABEL_ID = "start_label_id"

export const startLabel = newLabel(START_LABEL_ID,
    () => {
        return [
            (props) => GameStepManager.callLabel(anotherLabel, props),
            ({ navigate }) => { // last step
                // if you want to end the game when the steps are finished you can navigate to a route
                navigate('/end')
            },
        ]
    }
)

For example, if the game has no end:

const START_LABEL_ID = "start_label_id"
const GO_TO_NAVIGATION_LABEL_ID = "go_to_navigation_label_id2"

export const startLabel = newLabel(START_LABEL_ID,
    () => {
        return [
            (props) => GameStepManager.callLabel(prologueLabel, props),
            (props) => GameStepManager.callLabel(goToNavigation, props),
            ({ navigate }) => { // last step
                // at this point the game cannot pass
                navigate('/error')
            },
        ]
    }
)

/**
 * This label causes the player to return to navigation after completing a dialogue.
 * This label creates a loop, causing the game to never end.
 * Only if a jump is called immediately after this label, it will be terminated, moving on to the father label.
 */
const goToNavigation = newLabel(GO_TO_NAVIGATION_LABEL_ID,
    () => {
        return [
            ({ navigate }) => navigate('/navigation'),
            (props) => GameStepManager.jumpLabel(GO_TO_NAVIGATION_FATHER_LABEL_ID, props),
        ]
    }
)

The previous example is only functional if no jumps are used immediately after goToNavigation. To make it possible to use jumps, an intermediate label must be added as follows:

const START_LABEL_ID = "start_label_id"
const GO_TO_NAVIGATION_FATHER_LABEL_ID = "go_to_navigation_label_id"
const GO_TO_NAVIGATION_LABEL_ID = "go_to_navigation_label_id2"

export const startLabel = newLabel(START_LABEL_ID,
    () => {
        return [
            (props) => GameStepManager.callLabel(prologueLabel, props),
            (props) => GameStepManager.callLabel(goToNavigationFather, props),
            ({ navigate }) => { // last step
                // at this point the game cannot pass
                navigate('/error')
            },
        ]
    }
)

/**
 * This label ensures that even when {@link goToNavigation} is closed, {@link goToNavigation} is reopened.
 */
const goToNavigationFather = newLabel(GO_TO_NAVIGATION_FATHER_LABEL_ID,
    () => {
        return [
            (props) => GameStepManager.callLabel(goToNavigation, props),
            (props) => GameStepManager.jumpLabel(GO_TO_NAVIGATION_FATHER_LABEL_ID, props),
        ]
    }
)

/**
 * This label causes the player to return to navigation after completing a dialogue.
 * This label creates a loop, causing the game to never end.
 * Only if a jump is called immediately after this label, it will be terminated, moving on to the father label.
 */
const goToNavigation = newLabel(GO_TO_NAVIGATION_LABEL_ID,
    () => {
        return [
            ({ navigate }) => navigate('/navigation'),
            (props) => GameStepManager.jumpLabel(GO_TO_NAVIGATION_FATHER_LABEL_ID, props),
        ]
    }
)

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