開啟第二步的專案，給遊戲新增敵人enemies

自定義addTarget()函式來完成這項工作

使敵人從螢幕左邊出生，以一個隨機random的速度向左移動

在HelloWorldScene.h標頭檔案加入void addTarget()宣告

在HelloWorldScene.cpp檔案中實現該函式

並新增using namespace cocos2d引入cocos2d名稱空間

1// cpp with cocos2d-x
 2void HelloWorld::addTarget()
 3{
 4    CCSprite *target = CCSprite
 
::create("Target.png", 
 5        CCRectMake(0,0,27,40) );
 6
 7    // 設定敵人出生的Y軸座標
 8    CCSize winSize = CCDirector::sharedDirector()->getWinSize();
 9    int minY = target->getContentSize().height/2;
10    int maxY = winSize.height
11                          -  target->getContentSize().height/2;
12
 
    int rangeY = maxY - minY;
13    // srand( TimGetTicks() );
14    int actualY = ( rand() % rangeY ) + minY;
15
16    // Create the target slightly off-screen along the right edge,
17    // and along a random position along the Y axis as calculated
18    target->setPosition( 
19        ccp(winSize.width + (target->getContentSize().width/2
 
), 
20        actualY) );
21    this->addChild(target);
22
23    // 設定隨機速度
24    int minDuration = (int)2.0;
25    int maxDuration = (int)4.0;
26    int rangeDuration = maxDuration - minDuration;
27    // srand( TimGetTicks() );
28    int actualDuration = ( rand() % rangeDuration )
29                                        + minDuration;
30
31    // 建立移動動作，並設定動作的回撥函式
32    CCFiniteTimeAction* actionMove = 
33        CCMoveTo::create( (float)actualDuration, 
34        ccp(0 - target->getContentSize().width/2, actualY) );
35    CCFiniteTimeAction* actionMoveDone = 
36        CCCallFuncN::create( this, 
37        callfuncN_selector(HelloWorld::spriteMoveFinished));
38    target->runAction( CCSequence::create(actionMove, 
39        actionMoveDone, NULL) );
40}

// cpp with cocos2d-x
2void HelloWorld::spriteMoveFinished(CCNode* sender)
3{
4  CCSprite *sprite = (CCSprite *)sender;
5  this->removeChild(sprite, true);
6}

現在，敵人已經設計好了，接下來的工作就是把它創建出來

這裡將敵人以每秒一個的速率創建出來

在HelloWord::init()中新增

1// cpp with cocos2d-x
2// Call game logic about every second
3this->schedule( schedule_selector(HelloWorld::gameLogic), 1.0 );

並宣告定義HelloWorld::gameLogic(float dt)函式

1// cpp with cocos2d-x
2void HelloWorld::gameLogic(float dt)
3{
4    this->addTarget();
5}