Custom Targeting

In some cases, you may want a card that you can aim (targeting arrow) at something other than an enemy. This is what custom targeting is for.

Three things are required.

1. A TargetingHandler
2. A CardTarget enum
3. Registering your custom targeting

For an example, this is an implementation of targeting the player or an enemy, which you can use if it happens to be what you need. https://github.com/kiooeht/StSLib/blob/master/src/main/java/com/evacipated/cardcrawl/mod/stslib/cards/targeting/SelfOrEnemyTargeting.java#L23

At the top, you can see

    @SpireEnum
    public static AbstractCard.CardTarget SELF_OR_ENEMY;

This is the CardTarget for this handler.

To properly create a TargetingHandler, you need at minimum the following:

1. Extend the TargetingHandler class with an appropriate type parameter depending on what you want to target. In the example, this is AbstractCreature, as both the player and enemies extend this class.

2. Define the following methods:

    public abstract void updateHovered(); //Update/check what valid target is currently hovered
    public abstract void getHovered(); //Returns what is currently hovered (should just be null if none)
    public abstract void clearHovered(); //Clear current target when leaving targeting mode
    public abstract boolean hasTarget(); //Whether a valid target is hovered

Everything else is optional. Some of it for keyboard input support, and some of it for visuals.

In Slay the Spire, targeting works in two steps. First, while you're dragging the card and aiming the arrow, it tracks what target you're currently hovering. Then, when you release, the card is queued with that currently hovered target.

So, the first step is to create a tracking variable in your class that extends TargetingHandler to store the currently hovered target. You can see this here in the example.

Next, is the updateHovered method. This is the method that actually will check the possible targets to see what's currently hovered. In this case, the targets are the player or an enemy, so it checks those and stores the first one that's hovered.

Then there's the getHovered, clearHovered, and hasTarget methods. These are relatively self-explanatory, just performing basic actions on the hovered target variable.

Then the last step: registering it. This can be done at basically any time, but postInitialize is a good option. You can see this here; register your CardTarget and an instance of your TargetHandler.

For an example of how a card would actually use this custom targeting:

First, it would need to use the CardTarget. Set the card's CardTarget to your defined enum like you would with any other targeting option. Then, in the use method, access where you've stored the card's target. In the case of SelfOrEnemyTargeting, it might look like

    public void use(AbstractPlayer p, AbstractMonster m) {
        AbstractCreature target = SelfOrEnemyTargeting.getTarget(this);

        if (target == null)
            target = AbstractDungeon.player;

        addToBot(new GainBlockAction(target, p, this.block));
    }

You should always include a null check for safety. It's hard to guarantee that the card won't get played through some unusual method that doesn't target it, such as Mayhem, which only assigns a random monster target.