cocos2dx学习笔记：自定义动作实现圆周运动

From: http://cstriker1407.info/blog/cocos2dx-study-notes-custom-actions-realization-of-circular-motion/

最近在翻帖子的时候发现很多大牛都自己实现自定义动作，而不是通过各种动作进行组合，正好最近需要一个圆周运动的效果，就自己写了一个自定义的动作，这里备注下大致的实现思路。

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• 1备注：
• 2数学复习：
• 3实现方式：

备注：

该动作并未实际应用在游戏中，可能有bug。

数学复习：

截图来自【http://202.113.29.3/nankaisource/mathhands/Elementary%20mathematics/0103/010301/01030101.htm】

实现方式：

可参考这篇文章来实现：【http://www.jb51.cc/article/p-fdrufoeg-bcr.html】

作者自己也写了一个功能增强版的圆周运动，可以实现螺旋线式的圆周运动。代码比较简单，就不在细说了。

自己的实现：

CircleMoveAct.h：

#ifndef __CIRCLE_MOVE_ACT_H__

#define __CIRCLE_MOVE_ACT_H__

#include "cocos2d.h"

//http://202.113.29.3/nankaisource/mathhands/Elementary%20mathematics/0103/010301/01030101.htm

classCircleMoveAct :publiccocos2d::CCActionInterval

{

public:

boolinitWithDuration(floatduration,constcocos2d::CCPoint& center,scaleDiff,255)!important; border:0px!important; white-space:normal; margin:0px!important; outline:0px!important; text-align:left!important; float:none!important; vertical-align:baseline!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; height:auto!important; width:auto!important; line-height:1.1em!important; font-weight:normal!important; font-style:normal!important; min-height:inherit!important">angle);

virtualcocos2d::CCObject* copyWithZone(cocos2d::CCZone* pZone);

virtualvoidstartWithTarget(cocos2d::CCNode *pTarget);

update(floattime);

staticCircleMoveAct* create(scale,61)!important; border:0px!important; white-space:normal; margin:0px!important; outline:0px!important; text-align:left!important; float:none!important; vertical-align:baseline!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; height:auto!important; width:auto!important; line-height:1.1em!important; font-weight:bold!important; font-style:normal!important; min-height:inherit!important">protected:

m_duration;

cocos2d::CCPoint m_center;

m_scaleDiff;

m_currScale;

m_angle;

m_anglePreFrame;

intm_frameCnts;

cocos2d::CCPoint m_initPos;

};

#endif // __CIRCLE_MOVE_ACT_H__

CircleMoveAct.cpp：

#include "CircleMoveAct.h"

USING_NS_CC;

CircleMoveAct* CircleMoveAct::create(CCPoint& center,255)!important; border:0px!important; white-space:normal; margin:0px!important; outline:0px!important; text-align:left!important; float:none!important; vertical-align:baseline!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; height:auto!important; width:auto!important; line-height:1.1em!important; font-weight:normal!important; font-style:normal!important; min-height:inherit!important">angle)

CircleMoveAct *pRet =newCircleMoveAct();

pRet->initWithDuration(duration,center,scale,angle);

pRet->autorelease();

returnpRet;

}

CircleMoveAct::initWithDuration(angle)

{

if(CCActionInterval::initWithDuration(duration))

this->m_duration = duration;

->m_center = center;

->m_scaleDiff = scaleDiff;

->m_currScale = 1.0f;

->m_angle = angle;

/************************************************************************/

/* 计算每次update调用时需要转动的弧度 */

->m_anglePreFrame = angle / duration * CCDirector::sharedDirector()->getAnimationInterval() / (180 / M_PI);

->m_frameCnts = 0;

returntrue;

falseCCObject* CircleMoveAct::copyWithZone(CCZone *pZone)

CCZone* pNewZone = NULL;

CircleMoveAct* pcopy = NULL;

if(pZone && pZone->m_pcopyObject)

pcopy = (CircleMoveAct*)(pZone->m_pcopyObject);

}

else

pcopy =CircleMoveAct();

pZone = pNewZone =CCZone(pcopy);

CCActionInterval::copyWithZone(pZone);

pcopy->initWithDuration(m_duration,m_center,m_scaleDiff,m_angle);

CC_SAFE_DELETE(pNewZone);

pcopy;

CircleMoveAct::startWithTarget(CCNode *pTarget)

CCActionInterval::startWithTarget(pTarget);

m_initPos = pTarget->getPosition();

CircleMoveAct::update()

m_frameCnts++;

m_currScale += m_scaleDiff;

CCPoint newPos = ccpRotateByAngle(m_initPos,m_frameCnts * m_anglePreFrame);

CCPoint diff = ccpsub(newPos,m_center);

newPos = diff * m_currScale + m_center;

m_pTarget->setPosition(newPos);

//debug

#if 0

CCDrawNode *node = CCDrawNode::create();

node->drawDot(newPos,3,ccc4f(128,128,128));

m_pTarget->getParent()->addChild(node);

#endif

}