slide不显示slideball,求解代码如下
bgMusicVolumSlide = Slider::create();
bgMusicVolumSlide-> loadBarTexture("sliderProgress.png");
bgMusicVolumSlide->loadProgressBarTexture("slidebar.png");
bgMusicVolumSlide-> loadSlidBallTextureNormal("slideballnormal.png");
bgMusicVolumSlide->loadSlidBallTexturePressed("slideballpresswd.png");
bgMusicVolumSlide->setPercent(100);
bgMusicVolumSlide->setPosition(Vec2(100, 100));
bgMusicVolumSlide->addEventListener(CC_CALLBACK_1(SetScene::slideTest, this));
this->addChild(bgMusicVolumSlide,2);
```