How to create an ability

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Trowl3r

Hello everyone,

I am creating a 2D Sidesrollerer for a school project. Short Summary: it's basically a mix of super mario bros and banjo and kazooie with a kangaroo and a ostrich. I want to do a punch effect for the kangaroo, to box enemys. I dont really know how to do it with abilitys.

My Code:

Kangaroo.java:
private static Kangaroo instance;

private final Jump jump;
private int jumps;
private String playerState;
public static final int MAX_JUMPS = 1;
private KangarooPunsh punsh;

Kangaroo() {
    super("kangaroo");

    this.playerState = "IDLE";

    this.jump = new Jump(this);
    this.punsh = new KangarooPunsh(this);
    this.addController(new PlatformingMovementController<>(this));

    KeyboardEntityController<Kangaroo> movementController = new KeyboardEntityController<>(this);
    movementController.addUpKey(KeyEvent.VK_UP);
    movementController.addDownKey(KeyEvent.VK_DOWN);
    movementController.addLeftKey(KeyEvent.VK_LEFT);
    movementController.addRightKey(KeyEvent.VK_RIGHT);

    //Attack
    Input.keyboard().onKeyPressed(KeyEvent.VK_P, e->this.punsh());
}

@Action(description = "Punch the enemy in the fucking face and fuck him up")
public void punsh() {
    new KangarooPunsh(this);
    System.out.println("called");
}

public static Kangaroo instance() {
    // Work on this
    if(instance == null && GameData.getPlayerIndex() == 0) {
        instance = new Kangaroo();
    }

    return instance;
}

KangarooPunsh.java:

package abilites;

import de.gurkenlabs.litiengine.abilities.AbilityInfo;
import de.gurkenlabs.litiengine.abilities.Ability;
import de.gurkenlabs.litiengine.abilities.effects.EffectTarget;
import de.gurkenlabs.litiengine.entities.Creature;
import de.gurkenlabs.litiengine.entities.EntityPivotType;
import de.gurkenlabs.litiengine.entities.ICombatEntity;

@AbilityInfo(cooldown = 1000, range = 0, value = 1, multiTarget = true, duration = 500, origin = EntityPivotType.COLLISIONBOX_CENTER)
public class KangarooPunsh extends Ability {
public KangarooPunsh(Creature executor) {
super(executor);
this.addEffect(new KangarooPunschEffect(this, EffectTarget.ENEMY));
}
}

KangarooPunshEffect.java:

package abilites;

import de.gurkenlabs.litiengine.Game;
import de.gurkenlabs.litiengine.abilities.Ability;
import de.gurkenlabs.litiengine.abilities.effects.Effect;
import de.gurkenlabs.litiengine.abilities.effects.EffectTarget;
import de.gurkenlabs.litiengine.entities.Creature;
import de.gurkenlabs.litiengine.entities.ICombatEntity;
import de.gurkenlabs.litiengine.physics.Collision;

import java.awt.*;
import java.awt.geom.Line2D;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import java.util.ArrayList;
import java.util.Collection;

public class KangarooPunschEffect extends Effect {
private final Ability ability;

protected KangarooPunschEffect(final Ability ability, EffectTarget enemy) {
    super(ability, enemy);
    this.ability = ability;
}

@Override
public void apply(final ICombatEntity affectedEntity) {
    super.apply(affectedEntity);
    final int dmg = this.ability.getAttributes().value().get();
    affectedEntity.hit(dmg, this.getAbility());
    affectedEntity.die();
    System.out.println(affectedEntity.getHitPoints());
}



@Override
protected Collection<ICombatEntity> getEntitiesInImpactArea(final Shape impactArea) {
    final ArrayList<ICombatEntity> entities = new ArrayList<>();
    for(final ICombatEntity entity : Game.world().environment().findCombatEntities(impactArea, x -> x instanceof Creature)) {
        final Point2D collCenterExecutor = new Point2D.Double(
                this.getAbility().getExecutor().getCollisionBox().getCenterX(),
                this.getAbility().getExecutor().getCollisionBox().getCenterY());
        final Point2D collCenterEntity = new Point2D.Double(entity.getCollisionBox().getCenterX(),
                entity.getCollisionBox().getCenterY());
        final Line2D rayCast = new Line2D.Double(collCenterExecutor, collCenterEntity);

        boolean collision = false;
        for (final Rectangle2D collisionBox : Game.physics().getCollisionBoxes(Collision.STATIC)) {
            if (collisionBox.intersectsLine(rayCast)) {
                collision = true;
                break;
            }
        }
        if (!collision) {
            entities.add(entity);
        }
    }
    return entities;
}

protected Ability getPunchAbility() {
    return this.ability;
}

}

I need help fast. thanks for the help.

steffen

Guess the ability part of the documentation needs some work

Looking at the code of your Kangaroo class, I noticed the following method:

public void punsh() {
    new KangarooPunsh(this);
    System.out.println("called");
}

You are just calling the constructor of a new ability which is in your example unnecessary because you already created an instance in the constructor.
Basically, all abilities are executed when you call the Ability.cast() method. So in your case, the method should look like this:

public void punsh() {
    this.punsh.cast();
}

Also, see https://litiengine.com/api/de/gurkenlabs/litiengine/abilities/Ability/#cast() for "a few lines of documentation".

An Ability in general is designed such that it will execute all the registered Effects, once you call cast() and it will internally also take the cooldown into account.

Trowl3r

Thanks for the reply, I also noticed that, but when I am executing the cast() Method, nothing happens