在AndEngine中对多个实体修饰符进行排队

Question

I'm trying to have a sprite ("pointer" below) along two paths, one after the other. Here is my code:

    scene.attachChild(pointer);

    pointer.clearEntityModifiers();
    pointer.registerEntityModifier(new MoveModifier(
        1.0f, 540, 960, 1000, 1000,
        new IEntityModifierListener() {
            public void onModifierStarted(IModifier<IEntity> pModifier, IEntity pItem) {}
            public void onModifierFinished(IModifier<IEntity> pModifier, IEntity pItem) {
                clickSound.play();

                pointer.clearEntityModifiers();
                pointer.registerEntityModifier(new MoveModifier(
                    1.0f, pointer.getX(), pointer.getY(), 500, 2500,
                    new IEntityModifierListener() {
                        public void onModifierStarted(IModifier<IEntity> pModifier, IEntity pItem) {}
                        public void onModifierFinished(IModifier<IEntity> pModifier, IEntity pItem) {
                            pointer.clearEntityModifiers();
                            pointer.detachSelf();
                        }
                    },
                    EaseCubicInOut.getInstance()
                ));
            }
        },
        EaseCubicInOut.getInstance()
    ));

The pointer moves along the first path as expected, and then the clickSound plays, and then nothing happens. The second MoveModifier doesn't have any effect. What am I doing wrong here?

Answer 1

I'm not sure why your code is not working, but I think you can achieve the same thing using the SequenceEntityModifier :

scene.attachChild(pointer);

    pointer.clearEntityModifiers();
    pointer.registerEntityModifier(new SequenceEntityModifier(
        new MoveModifier#1(...),
        new MoveModifier#2(...)));

Answer 2

My first guess woud be, that the code after pointer.clearEntityModifiers(); isn't executed anymore, since it unregisters the modifiers. I am just thinking out loud here, so please tell me if I am wrong. Maybe you can try logging something to see if the method returns after this line. Something like:

pointer.clearEntityModifiers();
Log.v("EntityModifier", "the method continues...");

I always find it hard to manage internal class definitions, because of the state of the variables that are accessed from inside. Like in your case the pointer . If nothing else works, you could still try to do it all in one run. So instead of disposing the first modifier listener and registering another, create your own Listener, with a flag somewhere to tell it what to do and reuse that listener:

public class MyModifierListener extends IEntityModifierListener{

    private Pointer pointer;   // declare your pointer, so you have a reference within the listener
    private boolean firstRun;  // a flag to check if it is the first time the modifier is used

    public MyModifierListener(Pointer pointer){
        super();
        this.pointer = pointer;  // init the pointer within the constructor
        this.firstRun = true;    // should be true the first time
    }

    public void onModifierStarted(IModifier<IEntity> pModifier, IEntity pItem) {
    }

    public void onModifierFinished(IModifier<IEntity> pModifier, IEntity pItem) {
        if(firstRun){
             clickSound.play();
         firstRun=false;
             pointer.registerEntityModifier(new MoveModifier(1.0f, pointer.getX(), pointer.getY(), 500, 2500, this), EaseCubicInOut.getInstance());
        }else{
             pointer.detachSelf();
        }
    }
}

And to use it something like that:

MyModifierListener myListener = new MyModifierListener(pointer);
pointer.registerEntityModifier(new MoveModifier(1.0f, 540, 960, 1000, 1000,     myListener), EaseCubicInOut.getInstance());

I couldn't test this, so these are just wild guesses. Tell me if you find something.

regards Christoph