Example of having a child particle component

childParticles.md

So I have a component called ChildParticleComponent. My component has a few extra things as I've got differet requirements but I'll describe the most simple form possible.

ChildParticleComponent

My Version

public class ChildParticleComponent implements Component {
    public EntityRef particleEntity = EntityRef.NULL;
}

Helper Method

I use this to avoid duplicate code and to handle the case where there is no ChildParticleComponent yet gracefully.

private ChildrenParticleComponent getParticleComponent(EntityRef target) {
    ChildrenParticleComponent particleComponent;
    if (target.hasComponent(ChildrenParticleComponent.class)) {
        particleComponent = target.getComponent(ChildrenParticleComponent.class);
    } else {
        particleComponent = new ChildrenParticleComponent();
    }
    return particleComponent;
}

Adding

My Version

public void addParticleEffect(EntityRef target, EntityRef particleEntity) {
    if (target.exists()) {
        /* Get the particle entity */
        ChildrenParticleComponent particleComponent = getParticleComponent(target);
        particleComponent.particleEntity = particleEntity;

        /* Here we bind the child's Location Component to the parents */
        LocationComponent targetLoc = target.getComponent(LocationComponent.class);
        LocationComponent childLoc = particleEntity.getComponent(LocationComponent.class);
        childLoc.setWorldPosition(targetLoc.getWorldPosition());
        Location.attachChild(target, particleEntity);
        particleEntity.setOwner(target);

        /* Possibly not needed, but better safe than sorry */
        target.saveComponent(particleComponent);
    }
}

Removing

My Version

public EntityRef removeParticleEffect(EntityRef target) {
    ChildrenParticleComponent particleComponent = getParticleComponent(target);
    EntityRef child = particleComponent.particleEntity;
    target.removeComponent(ChildrenParticleComponent.class);
    return child;
}

Getting

Don't have a version as I don't need it

public EntityRef removeParticleEffect(EntityRef target) {
    ChildrenParticleComponent particleComponent = getParticleComponent(target);
    return particleComponent.particleEntity;
}

Notes

The actual method I have actually uses a Map<String, EntityRef> in order to allow for multiple particle effects on the one entity. I also pass in the prefab as I'm creating a new entity each time, not reusing the same one. I've linked to my version of the methods in the sections. Usage of my versions can be found in this system