如今来实现敌机类

敌机和我方飞机相似，具有生命值、能够发射子弹。而且有自己的运动轨迹。事实上能够为它们设计一个共同的基类，这样能够更方便扩展。

不同的敌机，应设置不同的标识、属性

// 敌机生命值
const int ENEMY1_MAXLIFE = 1;
const int ENEMY2_MAXLIFE = 2;
const int ENEMY3_MAXLIFE = 5;
const int ENEMY4_MAXLIFE = 10;// 敌机分数
const int ENEMY1_SCORE = 1;
const int ENEMY2_SCORE = 6;
const int ENEMY3_SCORE = 20;
const int ENEMY4_SCORE = 50;

// 敌机类型
enum EnemyType
{Enemy1 = 1,Enemy2,Enemy3,Enemy4,
};

头文件里的主要函数

void setEnemyByType(EnemyType enType);
Sprite* getSprite();int getLife();
void loseLife();
Rect getBoundingBox();

函数的实现

void Enemy::setEnemyByType(EnemyType enType)
{switch (enType){case Enemy1:pEnemySprite = Sprite::createWithSpriteFrame(SpriteFrameCache::getInstance()->getSpriteFrameByName("enemy1.png"));nLife = ENEMY1_MAXLIFE;break;case Enemy2:pEnemySprite = Sprite::createWithSpriteFrame(SpriteFrameCache::getInstance()->getSpriteFrameByName("enemy2.png"));nLife = ENEMY2_MAXLIFE;break;case Enemy3:pEnemySprite = Sprite::createWithSpriteFrame(SpriteFrameCache::getInstance()->getSpriteFrameByName("enemy3.png"));nLife = ENEMY3_MAXLIFE;break;case Enemy4:pEnemySprite = Sprite::createWithSpriteFrame(SpriteFrameCache::getInstance()->getSpriteFrameByName("enemy4.png"));nLife = ENEMY4_MAXLIFE;break;default:return;break;}this->addChild(pEnemySprite);Size winSize = Director::getInstance()->getWinSize();Size enemySize = pEnemySprite->getContentSize();int minX = enemySize.width / 2;int maxX = winSize.width - enemySize.width / 2;int rangeX = maxX - minX;int actualX = (rand() % rangeX) + minX;// 设置敌机Node方位 Node包括Spritethis->setPosition(Point(actualX, winSize.height - enemySize.height / 2));
}bool Enemy::init()
{bool pRet = true;if (!Node::init()){pRet = false;}return pRet;
}Sprite* Enemy::getSprite()
{return pEnemySprite;
}int Enemy::getLife()
{return nLife;
}void Enemy::loseLife()
{--nLife;
}Rect Enemy::getBoundingBox()
{Rect rect = pEnemySprite->boundingBox();Point pos = this->convertToWorldSpace(rect.origin);Rect enemyRect(pos.x, pos.y, rect.size.width, rect.size.height);return enemyRect;
}

依据敌机类型，绑定对应的图片和生命值，对于我方飞机。假设想依据生命值来设定不同的飞机样式，也能够通过此类方法。