【cocos2dx 3.2】Flappy Bird开发超详细讲解（三）预加载场景和开始场景

本节主要有3个类，LoadingScene,AnimatinoUtil和StartGame
先看AnimationUtil，代码如下，从木头的书里面搬过来的：

//AnimationUtil.h

#ifndef _ANIMATIONUTIL_H_
#define _ANIMATIONUTIL_H_
#include "cocos2d.h"
USING_NS_CC;

class AnimationUtil
{
public:
static Animation* createWithSingleFrameName(const char* name, float delay, int iLoops);
static Animation* createWithFrameNameAndNum(const char* name, int iNum, float delay, int iLoops);
};
#endif

//AnimationUtil.cpp

#include "AnimationUtil.h"

Animation* AnimationUtil::createWithSingleFrameName(const char* name, float delay, int iLoops)
{
SpriteFrameCache* cache = SpriteFrameCache::getInstance();
Vector<SpriteFrame*> frameVec;
SpriteFrame* frame = NULL;
int index = 0;
do
{
frame = cache->getSpriteFrameByName(StringUtils::format("%s%d.png", name, index++));
if (frame==NULL)
{
break;
}

frameVec.pushBack(frame);
} while (true);

Animation* animation = Animation::createWithSpriteFrames(frameVec);
animation->setDelayPerUnit(delay);
animation->setRestoreOriginalFrame(true);
animation->setLoops(iLoops);

return animation;
}

Animation* AnimationUtil::createWithFrameNameAndNum(const char* name, int iNum, float delay, int iLoops)
{
SpriteFrameCache* cache = SpriteFrameCache::getInstance();
SpriteFrame* frame = NULL;
Vector<SpriteFrame*> frameVec;
int index = 0;
for (index; index < iNum;index++)
{
frame = cache->getSpriteFrameByName(StringUtils::format("%s%d.png", name, index));
if (frame==NULL)
{
break;
}
frameVec.pushBack(frame);
}
Animation* animation = Animation::createWithSpriteFrames(frameVec);
animation->setDelayPerUnit(delay);
animation->setRestoreOriginalFrame(true);
animation->setLoops(iLoops);

return animation;
}

这个就是动画创建的辅助类，想想看，我们有三种不同颜色的小鸟，每只小鸟有一样的动画，如果给每只小鸟都创建动画的话，那么代码就重复了3次，我们本着尽量不让代码重复的原则，创建了这个辅助类。

接下来是LoadingScene，代码如下，看注释，挺好理解的.

//LoadingScene.h

#ifndef _LOADING_SCENE_H_
#define _LOADING_SCENE_H_
#include "cocos2d.h"
USING_NS_CC;
class LoadingScene :public Layer
{
public:
static Scene* createScene();
virtual bool init();
void loadingDone(float);
CREATE_FUNC(LoadingScene);
};

#endif

//LoadingScene.cpp

#include "LoadingScene.h"
#include "AnimationUtil.h"
#include "define.h"
#include "StartGame.h"

//创建场景
Scene* LoadingScene::createScene()
{
auto scene = Scene::create();
auto layer = LoadingScene::create();
scene->addChild(layer);
return scene;
}

//初始化
bool LoadingScene::init()
{
if (!Layer::init())
{
return false;
}

//加载图片帧缓存
SpriteFrameCache::getInstance()->addSpriteFramesWithFile("bird.plist");

//预加载声音文件
CocosDenshion::SimpleAudioEngine::getInstance()->preloadEffect("sounds/sfx_die.mp3");
CocosDenshion::SimpleAudioEngine::getInstance()->preloadEffect("sounds/sfx_hit.mp3");
CocosDenshion::SimpleAudioEngine::getInstance()->preloadEffect("sounds/sfx_point.mp3");
CocosDenshion::SimpleAudioEngine::getInstance()->preloadEffect("sounds/sfx_swooshing.mp3");
CocosDenshion::SimpleAudioEngine::getInstance()->preloadEffect("sounds/sfx_wing.mp3");

//预加载3只不同颜色的小鸟的动画,并添加到动画帧缓存
Animation* animation0 = AnimationUtil::createWithSingleFrameName("bird0_", BIRD_FRE, -1);
Animation* animation1 = AnimationUtil::createWithSingleFrameName("bird1_", BIRD_FRE, -1);
Animation* animation2 = AnimationUtil::createWithSingleFrameName("bird2_", BIRD_FRE, -1);
AnimationCache::getInstance()->addAnimation(animation0, BIRDANIMATION_0);
AnimationCache::getInstance()->addAnimation(animation1, BIRDANIMATION_1);
AnimationCache::getInstance()->addAnimation(animation2, BIRDANIMATION_2);

//启动定时器，调用场景切换
this->schedule(schedule_selector(LoadingScene::loadingDone));

return true;
}

void LoadingScene::loadingDone(float)
{
//切换场景
Director::getInstance()->pushScene(StartGame::createScene());
}

这个场景主要用来预加载一些东西，像图片缓存动画缓存，声音等。

接下来我们看StartGame，显示开始游戏场景，场景有个按钮，点击进行开始游戏

//StartGame.h

#ifndef _START_GAME_H_
#define _START_GAME_H_
#include "cocos2d.h"
USING_NS_CC;
class StartGame:public Layer
{
public:
static Scene* createScene();
virtual bool init();
CREATE_FUNC(StartGame);
void gameStart();
};

#endif

//StartGame.cpp

#include "StartGame.h"

Scene* StartGame::createScene()
{
auto scene = Scene::create();
auto layer = StartGame::create();
scene->addChild(layer);
return scene;

}

bool StartGame::init()
{
if (!Layer::init())
{
return false;
}
auto winSize = Director::getInstance()->getWinSize();
//添加背景
auto bg = Sprite::createWithSpriteFrameName("bg_day.png");
bg->setPosition(Point(winSize/2));
this->addChild(bg);
//添加小鸟
auto bird = Sprite::createWithSpriteFrameName("bird0_0.png");
bird->setPosition(Point(winSize.width/2,winSize.height*0.8));
this->addChild(bird);
//添加游戏开始按钮
auto spriteBtn = Sprite::createWithSpriteFrameName("button_play.png");
auto playBtn = MenuItemSprite::create(spriteBtn, spriteBtn, CC_CALLBACK_0(StartGame::gameStart,this));
auto menu = Menu::create(playBtn, NULL);
menu->setPosition(Point(winSize / 2));
this->addChild(menu);

return true;
}

void StartGame::gameStart()
{
log("gameStart");
}

大家有没有发现一个define.h，那是什么东东？哈哈，那是一个宏定义而已，详见代码，我直接搬过来了

//define.h

#pragma once

#define BIRDANIMATION_0					"birdAnimation_0"
#define	BIRDANIMATION_1					"birdAnimation_1"
#define BIRDANIMATION_2					"birdAnimation_2"
#define BIRD_FRE						0.1f
#define BIRD_RADIUS						15
#define LOADING_NUM						2
#define LOADING_FRE						0.5f
#define GRAVITY							Point(0,-980)
#define VELOCITY						Point(0,260)
#define THROUGH_HEIGHT					120
#define PIPE_UP							1001
#define PIPE_DOWN						1002
#define PIPE_RANGE						200
#define PIPE_X							300
#define PIPE_Y							-170
#define PIPE_TIME						3.0f
#define PIPE_FRE						1.5f
#define PIPE_VELOCITY					Point(-360,0)
#define LAND_VELOCITY					1.0/60
#define BIRD_DIE_ROTATION				90
#define SCORECARD_SHOW_TIME				0.6f
#define ADDSCORE_FRE					0.05f
#define CHANGESCENE_TIME				0.5f
#define MEDALS_0						5
#define MEDALS_1						10
#define MEDALS_2						15
#define MEDALS_3						20

这一期代码剧增，是不是吓到大家了，大家放心，认真看看，其实逻辑方面的基本没有，都是一些概念性的东西，有什么不懂的上网查一查就可以了，或者在这边留言，我会尽我所能解答的，当然太深奥的我也不懂

。

本期运行的结果如下：



我将本期的代码上传，地址链接: http://pan.baidu.com/s/1ntHUYSD 密码: 4zb3

大家记得在AppDelegate.cpp里面导入头文件，LoadingScene.h,还有将auto scene = HelloWorld::createScene();改成auto scene = LoadingScene::createScene();哦。