[Cocos2d塔防游戏开发]Cocos2dx-3.X完成塔防游戏《王国保卫战》--防御塔（二）之初级箭塔

该章节主要介绍如何制作初级箭塔

首先我们先观察下这个游戏的箭塔

这个游戏的箭塔都是拥有两个弓箭手。以初级塔为例，左右两边分别有两个弓箭手，可以攻击不同的目标，并且同时只有一个弓箭手在攻击。根据这个特性我们写一个BaseArrowTower

class BaseArrowTower: public BaseTower
{
public:protected:Sprite* shooter_1;//弓箭手1号Sprite* shooter_2;//弓箭手2号Sprite* towerBase;//塔int shootTag;//弓箭手标记void initTower(int level);//初始化弓箭塔void addTerrain();//添加塔坯子（就是那个都是塔下面那个都是弓箭的地面，不同地图有不同的坯子~）virtual Bullet* ArrowTowerBullet();//生成弓箭virtual void shoot(float dt);//射！
};

现在让我们看下防御塔建造过程：

1.选择建造类型

2.执行建造动画（进度条，冒烟等）

3.去除动画精灵，添加防御塔

4.开始攻击

同样用1级箭塔举例

class SimpleArrowTowerlvl1: public BaseArrowTower
{
public:bool init();//初始化CREATE_FUNC(SimpleArrowTowerlvl1);void updateTower();//升级void showUpdateMenu();//显示升级菜单Bullet* ArrowTowerBullet();//生成弓箭
private:void buildingAnimation();//开始建造动画void buildingSmokeAnimation(float dt);
};

其中init()函数会由BaseArrowTower中的CREATE_FUNC宏自动执行，在init()中依次初始化各个参数，并且执行建造动画buildingAnimation

其中建造动画就是添加进度条、建造动画精灵等动作

void SimpleArrowTowerlvl1::buildingAnimation()
{auto building = Sprite::create();auto constructing = Sprite::createWithSpriteFrameName("tower_constructing_0004.png");auto hpBgSprite = Sprite::createWithSpriteFrameName("buildbar_bg.png");hpBgSprite->setPosition(Point(constructing->getContentSize().width / 2, constructing->getContentSize().height /2+10));auto hpBar = ProgressTimer::create(Sprite::createWithSpriteFrameName("buildbar.png"));hpBar->setType(ProgressTimer::Type::BAR);hpBar->setMidpoint(Point(0, 0.5f));hpBar->setBarChangeRate(Point(1, 0));hpBar->setPercentage(0);hpBar->setPosition(Point(hpBgSprite->getContentSize().width / 2, hpBgSprite->getContentSize().height / 2 ));hpBgSprite->addChild(hpBar);constructing->addChild(hpBgSprite);building->addChild(constructing);addChild(building);hpBar->runAction(Sequence::create(ProgressTo::create(0.5f, 100), CallFuncN::create(CC_CALLBACK_0(Sprite::removeFromParent, building)), NULL));scheduleOnce(schedule_selector(SimpleArrowTowerlvl1::buildingSmokeAnimation),0.5f);
}

hpBar->runAction(Sequence::create(ProgressTo::create(0.5f, 100), CallFuncN::create(CC_CALLBACK_0(Sprite::removeFromParent, building)), NULL));是执行一个动画序列，首先是执行进度条的动画，时间0.5秒，从0-100，再执行removeFromParent将建造动画精灵移除。

再延迟0.5S执行scheduleOnce(schedule_selector(SimpleArrowTowerlvl1::buildingSmokeAnimation),0.5f);执行一个冒烟动画然后将塔添加进去（当然这里也可以写到上面的动画序列当中）

void SimpleArrowTowerlvl1::buildingSmokeAnimation(float dt)
{auto smoke = Sprite::createWithSpriteFrameName("effect_buildSmoke_0001.png");addChild(smoke,99);smoke->runAction(Sequence::create(Animate::create(AnimationCache::getInstance()->getAnimation("build_smoke")),CallFuncN::create(CC_CALLBACK_0(Sprite::removeFromParent, smoke)),NULL));SoundManager::playArcherReady();initTower(1);setListener();schedule(schedule_selector(SimpleArrowTowerlvl1::shoot), 1.0f);
}

并在1S后开始执行shoot攻击敌人

void BaseArrowTower::shoot(float dt)
{auto instance = GameManager::getInstance();checkNearestMonster();char temp1[20]; sprintf(temp1, "level%d_shoot_down", level); char temp2[20]; sprintf(temp2, "level%d_shoot_top", level);//根据等级生成图片名，保存临时变量if(nearestMonster!=NULL && nearestMonster->getCurrHp() > 0 ){auto currBullet = ArrowTowerBullet();Point shootVector = nearestMonster->baseSprite->getPosition() - this->getParent()->getPosition();//怪物精灵是在地图上添加的，而塔的父精灵才是在地图上添加的，所以要统一标准计算//计算防御塔与敌人之间的角度float startAngle = currBullet->getRotation();float endAngle = 0;auto pVectr = currBullet->getPosition()-shootVector;float angleRadians=atan(pVectr.y/pVectr.x);float angleDegrees = CC_RADIANS_TO_DEGREES(angleRadians);if(shootVector.x - currBullet->getPosition().x<=0)//敌人在坐标，需要向左攻击{startAngle = startAngle + abs(angleDegrees);//初始弓箭角度endAngle = -90;//弓箭结束角度，向下，即插入地面if(shootTag == 1)//轮到1号弓箭手{currBullet->setPosition(Point(0,30));//子弹设置在弓箭手所在位置	shooter_1->setFlippedX(true);//X轴翻转，即面向左边if(shootVector.y - currBullet->getPosition().y<=0){//执行攻击动画，AnimationCache是自定义的动画类，会根据传入图片名生成帧动画shooter_1->runAction(Animate::create(AnimationCache::getInstance()->getAnimation(temp1)));}else{shooter_1->runAction(Animate::create(AnimationCache::getInstance()->getAnimation(temp2)));}shootTag = 2;}else//轮到2号弓箭手{currBullet->setPosition(Point(10,30));		shooter_2->setFlippedX(true);if(shootVector.y - currBullet->getPosition().y<=0){shooter_2->runAction(Animate::create(AnimationCache::getInstance()->getAnimation(temp1)));}else{shooter_2->runAction(Animate::create(AnimationCache::getInstance()->getAnimation(temp2)));}shootTag = 1;}}else//敌人在右边，其他同上{startAngle = startAngle - abs(angleDegrees);endAngle = 270;if(shootTag == 1){currBullet->setPosition(Point(0,30));		shooter_1->setFlippedX(false);if(shootVector.y - currBullet->getPosition().y<=0){shooter_1->runAction(Animate::create(AnimationCache::getInstance()->getAnimation(temp1)));}else{shooter_1->runAction(Animate::create(AnimationCache::getInstance()->getAnimation(temp2)));}shootTag = 2;}else{currBullet->setPosition(Point(10,30));		shooter_2->setFlippedX(false);if(shootVector.y - currBullet->getPosition().y<=0){shooter_2->runAction(Animate::create(AnimationCache::getInstance()->getAnimation(temp1)));}else{shooter_2->runAction(Animate::create(AnimationCache::getInstance()->getAnimation(temp2)));}shootTag = 1;}}//贝叶斯弧线ccBezierConfig bezier;if(shootTag == 1)//播放射箭音效SoundManager::playArrowShoot1();elseSoundManager::playArrowShoot2();//计算贝叶斯曲线的两个控制点bezier.controlPoint_1 = Point(currBullet->getPosition().x,currBullet->getPosition().y+200); bezier.controlPoint_2 = Point(shootVector.x,shootVector.y+200);; bezier.endPosition = shootVector;auto action = Spawn::create(BezierTo::create(0.5f, bezier),RotateTo::create(0.5f,endAngle),NULL);//攻击动画传递弓箭currBullet->setBulletAction(action);currBullet->shoot();currBullet = NULL;}
}

根据角度使用ccBezierConfig类来生成BezierTo移动动画，是一个弧线，具体内容百度的到

然后用Spwan将BezierTo与弓箭旋转动画合成为一个action，将action传递给子弹类，由子弹类具体执行，为何不在塔类中执行，将在子弹章节中讲解。

执行子弹类的shoot，攻击动画完成