I'm making a board game and I'm stuck on problem that's been killing 3-4 hours for me now. No docs anywhere so I'm just doing guesswork without luck.

Consider this:

public void highlightBlockTest(BoardCoordinate bc) {
  Log.i("highlightBlock()", "entered.");

  Point p = new Point(bc.getPuzzlePiece().getDestination());
  Rect rect = getBoardCoordinateRectFromPoint(p);

  int x = rect.getX();
  int y = rect.getY();
  int w = rect.getWidth();
  int h = rect.getHeight();

  Entity e = new Entity(0, 0);
  Rectangle r;

  r = new Rectangle(x, y, w, 5);
  e.attachChild(r);
  r = new Rectangle(x, y, 5, h);
  e.attachChild(r);
  r = new Rectangle(x + w - 5, y, 5, h);
  e.attachChild(r);
  r = new Rectangle(x, y + h - 5, w, 5);
  e.attachChild(r);

  SequenceEntityModifier sem = new SequenceEntityModifier(
      new DelayModifier(1f),
      new AlphaModifier(1f, 0.0f, 1.0f, new IEntityModifierListener() {
        @Override
        public void onModifierStarted(IModifier<IEntity> arg0, IEntity arg1) {
          System.out.println("Alpha start!");
        }

        @Override
        public void onModifierFinished(IModifier<IEntity> arg0, IEntity arg1) {
          System.out.println("Alpha stop!");
        }
      })
  ); 

  e.registerEntityModifier(sem);
  this.mScene.attachChild(e);

  return;
}

This code is supposed to draw a "highlight" rectangle for a particular block. The rectangle draws all right, but the AlphaModifier does not applicate its values on the entity in question. The DelayModifier works just fine.

I added ModifierListener just to see if it gets called, and it does; I see "Alpha start" and "Alpha stop" in Logcat. But the highlighted rectangle is still there, clearly visible on the board.

As a last resort I added a MoveModifier as well to move the rectangle 50 pixels to the right during 5 seconds, and the rectangle was moved off screen instantaneous.

Why aren't these modifiers working as expected?

• java
• android
• andengine

You need to set the blend function, call .setBlendFunction(GL10.GL_SRC_ALPHA, GL10.GL_ONE_MINUS_SRC_ALPHA); on the entities.