cocos2d-x横版格斗游戏教程3



这一篇要为英雄创造一些小伙伴了，并且需要让机器人会巡逻，会偷懒，会行走，还会攻击英雄，当然也能受伤。其实机器人和英雄有一些共同的属性：攻击力、生命值和行走速度。但机器人是由电脑控制，状态是随机切换的，所以还需要指定巡逻区域、攻击区域、行走方向、决策时间等。

1. 添加机器人

首先更新BaseSprite类，添加攻击力和生命值属性，在BaseSprite.h中添加：

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CC_SYNTHESIZE(unsignedint, m_hp, HP);

CC_SYNTHESIZE(unsignedint, m_attack, Attack);

创建Enemy类，代表敌方机器人，这里需要实现简单的AI，让机器人能自动思考，根据具体环境切换自己的状态：

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Enemy.h

typedefenum {

 AI_IDLE = 0,

 AI_PATROL,

 AI_ATTACK,

 AI_PURSUIT

}AiState;

classEnemy : publicBaseSprite

{

public:

 Enemy();

 ~Enemy();

 boolinit();

 CREATE_FUNC(Enemy);

 CC_SYNTHESIZE(cocos2d::Point, m_moveDirection, MoveDirection);

 CC_SYNTHESIZE(float, m_eyeArea, EyeArea);

 CC_SYNTHESIZE(float, m_attackArea, AttackArea)

 CC_SYNTHESIZE(AiState, m_aiState, AiState);

 voidexecute(constcocos2d::Point& target, floattargetBodyWidth);

private:

 voiddecide(constcocos2d::Point& target, floattargetBodyWidth);

 unsignedint m_nextDecisionTime;

};

AiState表示机器人的四种状态：休闲、巡逻、攻击、跟随。机器人还有几个变量，分别表示：行走方向、巡逻范围、攻击范围、当前AI状态。
m_nextDecisionTime表示机器人距离下一次决策的时间，execute函数是在GameLayer.cpp中update函数调用的，定期执行更新机器人状态。decide函数实现机器人怎么决策，是机器人的内心世界。
这里重点分析机器人AI该怎么实现，因为只是一个demo，所以就尽可能的简单些吧。首先机器人需要根据自己的朝向和英雄的位置来思考，如果机器人背对着英雄或者英雄处于机器人巡逻范围之外，那么此时机器人是看不到英雄的，机器人就会随机的选择继续巡逻或者站着偷懒。如果英雄在机器人的巡逻范围内，且被机器人看到了，则机器人需要判断英雄是否处于自己的攻击范围，来决策是攻击还是追过去。每种状态下的思考时间最好设置成随机的，这样更真实。看源码实现：

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Enemy.cpp

Enemy::Enemy():

 m_nextDecisionTime(0)

{}

  

Enemy::~Enemy()

{}

  

bool Enemy::init()

{

 boolret = false;

 do{

  this->initWithSpriteFrameName("robot_idle_00.png");

  Animation *pIdleAnim =this->createAnimation("robot_idle_%02d.png", 5, 12);

  this->setIdleAction(RepeatForever::create(Animate::create(pIdleAnim)));

  Animation *pWalkAnim =this->createAnimation("robot_walk_%02d.png", 6, 12);

  this->setWalkAction(RepeatForever::create(Animate::create(pWalkAnim)));

  

  Animation *pAttackAnim =this->createAnimation("robot_attack_%02d.png", 5, 20);

  this->setAttackAction(Sequence::create(Animate::create(pAttackAnim), BaseSprite::createIdleCallbackFunc(), NULL));

  Animation *pHurtAnim =this->createAnimation("robot_hurt_%02d.png", 3, 20);

  this->setHurtAction(Sequence::create(Animate::create(pHurtAnim), BaseSprite::createIdleCallbackFunc(), NULL));

  Animation *pDeadAnim =this->createAnimation("robot_knockout_%02d.png", 5, 12);

  this->setDeadAction(Sequence::create(Animate::create(pDeadAnim), Blink::create(3, 9), NULL));

  ret =true;

 }while(0);

 returnret;

}

  

voidEnemy::execute(constPoint& target, floattargetBodyWidth)

{

 if(m_nextDecisionTime == 0)

 {

  this->decide(target, targetBodyWidth);

 }else{

  -- m_nextDecisionTime;

 }

}

  

voidEnemy::decide(constPoint& target, floattargetBodyWidth)

{

 Point location =this->getPosition();

 floatdistance = location.getDistance(target);

 distance = distance - (targetBodyWidth / 2 +this->getDisplayFrame()->getRect().size.width / 2) + 30;

 //log("distance=%f, m_fVelocity=%f", distance, m_fVelocity);

 boolisFlippedX = this->isFlippedX();

 boolisOnTargetLeft = (location.x < target.x ? true: false);

 if((isFlippedX && isOnTargetLeft) || (!isFlippedX && !isOnTargetLeft)) {

  this->m_aiState = CCRANDOM_0_1() > 0.5f ? AI_PATROL : AI_IDLE;

 }else{

  if(distance < m_eyeArea)

  {

   this->m_aiState = distance < m_attackArea ? AI_ATTACK : AI_PURSUIT;

  }else{

   this->m_aiState = CCRANDOM_0_1() > 0.5f ? AI_PATROL : AI_IDLE;

  }

 }

 switch(m_aiState)

 {

 caseAI_ATTACK:

  {

   this->runAttackAction();

   this->attack();

   this->m_nextDecisionTime = 50;

  }

  break;

 caseAI_IDLE:

  {

   this->runIdleAction();

   this->m_nextDecisionTime = CCRANDOM_0_1() * 100;

  }

  break;

 caseAI_PATROL:

  {

   this->runWalkAction();

   this->m_moveDirection.x = CCRANDOM_MINUS1_1();

   this->m_moveDirection.y = CCRANDOM_MINUS1_1();

   m_moveDirection.x = m_moveDirection.x > 0 ? (m_moveDirection.x + m_fVelocity.x) : (m_moveDirection.x - m_fVelocity.x);

   m_moveDirection.y = m_moveDirection.y > 0 ? (m_moveDirection.y + m_fVelocity.y) : (m_moveDirection.y - m_fVelocity.y);

   this->m_nextDecisionTime = CCRANDOM_0_1() * 100;

  }

  break;

 caseAI_PURSUIT:

  {

   this->runWalkAction();

   //v.normalize() function return the unit vector of v

   this->m_moveDirection = (target - location).normalize();

   this->setFlippedX(m_moveDirection.x < 0 ?true : false);

   m_moveDirection.x = m_moveDirection.x > 0 ? (m_moveDirection.x + m_fVelocity.x) : (m_moveDirection.x - m_fVelocity.x);

   m_moveDirection.y = m_moveDirection.y > 0 ? (m_moveDirection.y + m_fVelocity.y) : (m_moveDirection.y - m_fVelocity.y);

   this->m_nextDecisionTime = 10;

  }

  break;

 }

}

当机器人思考接下来该做什么时，就会执行相应的操作和动画。
机器人创造完成了，现在把它添加到游戏中去，修改GameLayer.h，添加下面的代码：

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#define MIN_ENEMY_COUNT 5

  

 voidupdateEnemies(floatdt);

 voidaddEnemy();

 voidonEnemyAttack(BaseSprite *pSprite);

  

 cocos2d::Array *m_pEnemies;

updateEnemies表示每一次循环都会更新每个机器人的状态，onEnemyAttack是机器人攻击英雄时执行的函数，暂时不实现。m_pEnemies为保存机器人的容器。
修改GameLayer.cpp，添加下面的函数：

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void GameLayer::addEnemy()

{

 Size winSize = Director::getInstance()->getWinSize();

 Point location = Point::ZERO;

 Enemy *pEnemy = Enemy::create();

 //log("m_pTiledMap->getMapSize() mapSize=%f", m_pTiledMap->getMapSize().width);

 floathalfEnemyFrameHeight = (pEnemy->getDisplayFrame()->getRect().size.height) / 2;

 floatheroPosX = m_pHero->getPositionX();

 floathalfWinWidth = (winSize.width / 2);

 while(fabsf(heroPosX - location.x) < 150)

 {

  if(heroPosX < halfWinWidth)

  {

   location.x = m_pHero->getPositionX() + CCRANDOM_0_1() * halfWinWidth;

  }elseif(heroPosX > (m_pTiledMap->getMapSize().width * m_fTileWidth - halfWinWidth)) {

   location.x = m_pHero->getPositionX() - CCRANDOM_0_1() * halfWinWidth;

  }else{

   location.x = m_pHero->getPositionX() + CCRANDOM_MINUS1_1() * halfWinWidth;

  }

 }

 floatmaxY = m_fTileHeight * 3 + halfEnemyFrameHeight;

 location.y = CCRANDOM_0_1() * maxY;

 if(location.y < halfEnemyFrameHeight)

 {

  location.y = halfEnemyFrameHeight;

 }

 pEnemy->attack = CC_CALLBACK_0(GameLayer::onEnemyAttack,this, pEnemy);

 pEnemy->setPosition(m_origin + location);

 pEnemy->setZOrder(m_fScreenHeight - pEnemy->getPositionY());

 pEnemy->runIdleAction();

 pEnemy->setAttack(5);

 pEnemy->setHP(30);

 pEnemy->setVelocity(Point(0.5f, 0.5f));

 pEnemy->setEyeArea(200);

 pEnemy->setAttackArea(25);

 m_pEnemies->addObject(pEnemy);

 m_pSpriteNodes->addChild(pEnemy);

}

  

voidGameLayer::updateEnemies(floatdt) {

    Object *pObj = NULL;

 Point distance = Point::ZERO;

  

 Point heroLocation = m_pHero->getPosition();

 Array *pRemovedEnemies = Array::create();

    CCARRAY_FOREACH(m_pEnemies, pObj)

 {

  Enemy *pEnemy = (Enemy*)pObj;

  pEnemy->execute(heroLocation, m_pHero->getDisplayFrame()->getRect().size.width);

  if(pEnemy->getCurrActionState() == ACTION_STATE_WALK)

  {

   Point location = pEnemy->getPosition();

   Point direction = pEnemy->getMoveDirection();

  

   Point expect = location + direction;

   floathalfEnemyFrameHeight = (pEnemy->getDisplayFrame()->getRect().size.height) / 2;

   if(expect.y < halfEnemyFrameHeight || expect.y > (m_fTileHeight * 3 + halfEnemyFrameHeight) )

   {

    direction.y = 0;

   }

   pEnemy->setFlippedX(direction.x < 0 ?true : false);

   pEnemy->setPosition(location + direction);

   pEnemy->setZOrder(pEnemy->getPositionY());

  }

 }

 CCARRAY_FOREACH(pRemovedEnemies, pObj)

 {

  Enemy *pEnemy = (Enemy*)pObj;

  m_pEnemies->removeObject(pEnemy);

  m_pSpriteNodes->removeChild(pEnemy,true);

 }

 pRemovedEnemies->removeAllObjects();

}

  

voidGameLayer::onEnemyAttack(BaseSprite *pSprite)

{

}

在GameLayer.cpp的update函数中添加：

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this->updateEnemies(dt);

在init函数中添加：

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m_pEnemies = Array::createWithCapacity(MIN_ENEMY_COUNT);

 m_pEnemies->retain();

 for(inti = 0; i < MIN_ENEMY_COUNT; ++ i)

 {

  this->addEnemy();

 }

OK，现在编译运行项目，就可以看到屏幕上有5个机器人追着英雄打了，效果如下图：

目前机器人和英雄都没有攻击效果，都是无敌状态，不过他们好日子快到头了，下一篇我们就来让他们接受现实的残酷吧。