A pop-up over an entity's head that can be used to give some information about the entity. For eg, when used on an AI, whether it is puzzled, hostile, sleeping etc.

1. Exclamation

2. Question (it's inverted on purpose)

3. Knocked Out

There are two ways to add an indicator.

1. Simply add the indicator component to an entity specifying the indicator uri. However in this approach you must check if an indicator component is already present and if so remove the old one.

if(entity.hasComponent(IndicatorComponent.class))
    entity.removeComponent(IndicatorComponent.class);
entity.addComponent(new IndicatorComponent("Indicators:knockedOutIndicator"));

2. Send a DisplayIndicatorEvent which performs the check for you.

entity.send(new DisplayIndicatorEvent(new IndicatorComponent("Indicators:knockedOutIndicator")));

To remove an indicator, simply remove the component.

entity.removeComponent(IndicatorComponent.class);