Cocos2d-x CCProgressTimer

CCProgressTimer,创建使用这个节点可以大致实现两个作用的效果:

其一:在游戏中几乎大部分的游戏启动界面都是游戏加载画面,那么用到的一般是进度条提示加载进度,其使用的就是CCProgressTimer。

其二:在游戏中需要对精灵的出现等动作制作一些渐显的效果。

(1)类型一般就是两种:

typedef enum {
    /// Radial Counter-Clockwise
    kCCProgressTimerTypeRadial,
    /// Bar
    kCCProgressTimerTypeBar,
} CCProgressTimerType;

(2)类型1:radial(环形)

CCSize wSize = CCDirector::sharedDirector()->getWinSize();
    progressTimer = CCProgressTimer::create(CCSprite::create("progress.gif"));
    progressTimer->setType(kCCProgressTimerTypeRadial);
    // 默认的情况下,环形渐变的方向是:顺时针
    // 改变其渐变的方向 Makes the ridial CCW (逆时针)
    progressTimer->setReverseProgress(true);
    progressTimer->setPosition(wSize.width/2,wSize.height/2);
    this->addChild(progressTimer);


(3)类型2:bar  (条形:包括vertical 和 horizontal)

渐变的方向问题:

vertical竖直方法包括从上到下和从下到上;

horizontal水平方向包括从左到右和从右到左。

这里涉及到两个设置参数:

首先是setMidpoint设置起点

/**
     *    Midpoint is used to modify the progress start position.
     *    If you're using radials type then the midpoint changes the center point
     *    If you're using bar type the the midpoint changes the bar growth
     *        it expands from the center but clamps to the sprites edge so:
     *        you want a left to right then set the midpoint all the way to ccp(0,y)
     *        you want a right to left then set the midpoint all the way to ccp(1,y)
     *        you want a bottom to top then set the midpoint all the way to ccp(x,0)
     *        you want a top to bottom then set the midpoint all the way to ccp(x,1)
     */

其次是setBarChangeRate设置变化rate

/**
     *    This allows the bar type to move the component at a specific rate
     *    Set the component to 0 to make sure it stays at 100%.
     *    For example you want a left to right bar but not have the height stay 100%
     *    Set the rate to be ccp(0,1); and set the midpoint to = ccp(0,.5f);
     */

如果不用变化的方向,则设置该方向为0,否则设置为1。

CCSize wSize = CCDirector::sharedDirector()->getWinSize();
    progressTimer = CCProgressTimer::create(CCSprite::create("progress.gif"));
    progressTimer->setType(kCCProgressTimerTypeBar);
    
    //从左到右
    progressTimer->setMidpoint(ccp(0, 0.5));
    progressTimer->setBarChangeRate(ccp(1, 0));
    
    //从右到左
//    progressTimer->setMidpoint(ccp(1, 0.5));
//    progressTimer->setBarChangeRate(ccp(1, 0));
    
    //从上到下
//    progressTimer->setMidpoint(ccp(0.5, 1));
//    progressTimer->setBarChangeRate(ccp(0, 1));
    
    //从下到上
//    progressTimer->setMidpoint(ccp(0.5, 0));
//    progressTimer->setBarChangeRate(ccp(0, 1));
    
    progressTimer->setPosition(wSize.width/2,wSize.height/2);
    this->addChild(progressTimer);

(4) 执行变化

①、如果是要实现精灵渐变的显示效果:

创建CCProgressTo或者是CCProgressFromTo动作,让CCProgressTimer执行。
CCProgressTo和CCProgressFromTo的区别是:

前者:Progress to percentage(初始化有两个参数)(float duration, float fPercent)

后者:Progress from a percentage to another percentage(初始化有三个参数)(float duration, float fFromPercentage, float fToPercentage)

CCProgressTo *progressTo = CCProgressTo::create(2.0, 100);
    //等价于:
    //CCProgressFromTo *progressFromTo = CCProgressFromTo::create(2.0, 0, 100);
    progressTimer->runAction(CCRepeatForever::create(progressTo));

②、如果是要实现加载进度条的效果:

需要重载update方法,在这个方法中实现进度条percentage的变化。

this->scheduleUpdate();

void HelloWorld::update(float dt)
{
    float percentage = progressTimer->getPercentage();
    
    if (percentage < 100) {
        percentage += 1;
        progressTimer->setPercentage(percentage);
    }
}


关于CCProgressTimer的更加详细的使用 demo可以参看引擎中sample中的ActionProgressTest。

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