private float getCurrentAlphaRatio(){
    float delta=(myEndRatio-myStartRatio)/(float)TOTAL_FRAME_COUNT;
    if(myStartRatio>myEndRatio){ // dialog is becoming non transparent quicker
      delta*=2;
    }
    final float ratio=myStartRatio+(float)myCurrentFrame*delta;
    return MathUtil.clamp(ratio, .0f, 1.0f);
  }
private float getCurrentAlphaRatio()