Knob in DigitalOnScreenControl not moving. Why?

Question

I have set up a DigitalOnScreenControl in my game but the knob does not move. The base and the knob are drawn on the screen but the latter doesn't move as per the AndEngine example here.

Here is a snippet of my code:

this.mDigitalOnScreenControl = new DigitalOnScreenControl(300, 300, ResourceManager.getCamera(), ResourceManager.joystickControlBase,
                ResourceManager.joystickControlKnob, 0.1f, ResourceManager.getActivity().getVertexBufferObjectManager(),
                new IOnScreenControlListener() {

            @Override
            public void onControlChange(final BaseOnScreenControl pBaseOnScreenControl, final float pValueX,
                    final float pValueY) {
                    Log.v(TAG, "onControlChange");
            }
        });

        final Sprite controlBase = this.mDigitalOnScreenControl.getControlBase();
        final Sprite knob = this.mDigitalOnScreenControl.getControlKnob();
        controlBase.setAlpha(0.5f);
        controlBase.setOffsetCenter(0, 0);
        controlBase.setScaleCenter(10, 10);
                    controlBase.setScale(1.25f);
        knob.setScale(1.25f);
        this.mDigitalOnScreenControl.refreshControlKnobPosition();
        ResourceManager.getEngine().getScene().attachChild(this.mDigitalOnScreenControl);

The mDigitalOnScreenControl is a DigitalOnScreenControl object defined previously. I use a ResourceManager class to obtain texture regions and other game resources such as the camera amongst others. Note: Since the base and the knob are drawn, the ITextureRegions returned by the ResourceManager are valid. When I execute the program, there are no errors in DDMS.

The knob just doesn't move. Does anybody have an idea?

Thank you!

Answer 1

The DigitalOnScreenControl cannot be attached as a child to a scene. It must be attached as a childscene to the Engine's current Scene.

ResourceManager.getInstance().engine.getScene().setChildScene(joystickControl);

In the above code, joystickControl extends a DigitalOnScreenControl object. After that, depending on how your game is organised, you may need to sort the scenes, in case the DigitalOnScreenControl does not appear.

ResourceManager.getInstance().engine.getScene().sortChildren();

Also, read Cameron Fredman's comment why it is sensible to add the DigitalOnScreenControl object as a childscene.