cocos2d實現文本框到處彈的效果

實現將一個hello world 的label碰到邊界就彈回的效果。

#include "HelloWorldScene.h"

USING_NS_CC;

Scene* HelloWorld::createScene()
{
    // 'scene' is an autorelease object
    auto scene = Scene::create();
    
    // 'layer' is an autorelease object
    auto layer = HelloWorld::create();

    // add layer as a child to scene
    scene->addChild(layer);

    // return the scene
    return scene;
}

// on "init" you need to initialize your instance
bool HelloWorld::init()
{
    //////////////////////////////
    // 1. super init first
    if ( !Layer::init() )
    {
        return false;
    }
    
    Size visibleSize = Director::getInstance()->getVisibleSize();
    Vec2 origin = Director::getInstance()->getVisibleOrigin();

    /////////////////////////////
    // 2. add a menu item with "X" image, which is clicked to quit the program
    //    you may modify it.

    // add a "close" icon to exit the progress. it's an autorelease object
    auto closeItem = MenuItemImage::create(
                                           "CloseNormal.png",
                                           "CloseSelected.png",
                                           CC_CALLBACK_1(HelloWorld::menuCloseCallback, this));
    
	closeItem->setPosition(Vec2(origin.x + visibleSize.width - closeItem->getContentSize().width/2 ,
                                origin.y + closeItem->getContentSize().height/2));

    // create menu, it's an autorelease object
    auto menu = Menu::create(closeItem, NULL);
    menu->setPosition(Vec2::ZERO);
    this->addChild(menu, 1);

    /////////////////////////////
    // 3. add your codes below...

    // add a label shows "Hello World"
    // create and initialize a label
	
    auto label = Label::createWithTTF("Hello World", "fonts/Marker Felt.ttf", 24);

	label->setTag(123);
    
    // position the label on the center of the screen
    label->setPosition(Vec2(origin.x + visibleSize.width/2,
                            origin.y + visibleSize.height - label->getContentSize().height));

    // add the label as a child to this layer
    this->addChild(label, 1);

    // add "HelloWorld" splash screen"
    auto sprite = Sprite::create("HelloWorld.png");

    // position the sprite on the center of the screen
    sprite->setPosition(Vec2(visibleSize.width/2 + origin.x, visibleSize.height/2 + origin.y));

    // add the sprite as a child to this layer
    this->addChild(sprite, 0);
    
	this->scheduleUpdate();

    return true;
}


void HelloWorld::menuCloseCallback(Ref* pSender)
{
	unscheduleUpdate();

    Director::getInstance()->end();

#if (CC_TARGET_PLATFORM == CC_PLATFORM_IOS)
    exit(0);
#endif
}

void HelloWorld::update(float dt)
{
	auto label = this->getChildByTag(123);
	Size visibleSize = Director::getInstance()->getVisibleSize();
	Vec2 origin = Director::getInstance()->getVisibleOrigin();

	//方向，0右下，1左下，2左上，3右上

	static int dir = 0;
	if (0 == dir)
	{
		if (label->getPositionX() == visibleSize.width) dir = 1;
		if (label->getPositionY() == origin.y) dir = 3;
		if (label->getPositionX() == visibleSize.width &&
			label->getPositionY() == origin.y) dir = 2;
	}

	if (1 == dir)
	{
		if (label->getPositionX() == origin.x) dir = 0;
		if (label->getPositionY() == origin.y) dir = 2;
		if (label->getPositionX() == origin.x &&
			label->getPositionY() == origin.y) dir = 3;
	}

	if (2 == dir)
	{
		if (label->getPositionX() == origin.x) dir = 3;
		if (label->getPositionY() == visibleSize.height) dir = 1;
		if (label->getPositionX() == origin.x &&
			label->getPositionY() == visibleSize.height) dir = 0;
	}

	if (3 == dir)
	{
		if (label->getPositionX() == visibleSize.width) dir = 2;
		if (label->getPositionY() == visibleSize.height) dir = 0;
		if (label->getPositionX() == visibleSize.width &&
			label->getPositionY() == visibleSize.height) dir = 1;
	}

//	CCLOG("%f %f\n", label->getPositionX(), label->getPositionY());

	//右下
	if (0 == dir) label->setPosition(label->getPosition() + Vec2(1, -1));
	//左下
	if (1 == dir) label->setPosition(label->getPosition() + Vec2(-1, -1));
	//左上
	if (2 == dir) label->setPosition(label->getPosition() + Vec2(-1, 1));
	//右上
	if (3 == dir) label->setPosition(label->getPosition() + Vec2(1, 1));
}