Cocos2dx 像素判断碰撞检测

原创 于 2014-03-18 21:40:45 发布 · 2.1k 阅读 · 1 ·
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本文详细介绍了如何在Cocos2d-x游戏引擎中进行像素级别的碰撞检测，通过实例代码解析了关键步骤，包括获取精灵的像素数据、比较颜色差异以及判断碰撞发生，确保精确的碰撞响应。

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最近研究了一下透明图片的点击事件即png图片中透明区域的点击。当时用j2me的时候，记得设置个值就可以处理是像素点击还是图片点击，不对，是碰撞检测。看了看jdk，它处理了像素，处理如下：
  1. public void handlesinglepixel(int x, int y, int pixel) {
  2. int alpha = (pixel >> 24) & 0xff;
  3. int red = (pixel >> 16) & 0xff;
  4. int green = (pixel >> 8) & 0xff;
  5. int blue = (pixel ) & 0xff;
  6. // Deal with the pixel as necessary...
  7. }
复制代码



这时候使用的像素格式是ARGB。
  1. bool CCTexture2D::initPremultipliedATextureWithImage(CCImage *image, unsigned int width, unsigned int height)

  3. {

  5. unsigned char* tempData = image->getData();

  7. this->setFDImageData(tempData);

  9. unsigned int* inPixel32 = NULL;

  11. unsigned char* inPixel8 = NULL;

  13. unsigned short* outPixel16 = NULL;

  15. bool hasAlpha = image->hasAlpha();

  17. CCSize imageSize = CCSizeMake((float)(image->getWidth()), (float)(image->getHeight()));

  19. CCTexture2DPixelFormat pixelFormat;

  21. size_t bpp = image->getBitsPerComponent();

  23. // compute pixel format

  25. if(hasAlpha)

  27. {

  29. pixelFormat = g_defaultAlphaPixelFormat;

  31. }

  33. else

  35. {

  37. if (bpp >= 8)

  39. {

  41. pixelFormat = kCCTexture2DPixelFormat_RGB888;

  43. }

  45. else

  47. {

  49. pixelFormat = kCCTexture2DPixelFormat_RGB565;

  51. }

  53. }

  55. // Repack the pixel data into the right format

  57. unsigned int length = width * height;

  59. if (pixelFormat == kCCTexture2DPixelFormat_RGB565)

  61. {

  63. if (hasAlpha)

  65. {

  67. // Convert "RRRRRRRRRGGGGGGGGBBBBBBBBAAAAAAAA" to "RRRRRGGGGGGBBBBB"

  69. tempData = new unsigned char[width * height * 2];

  71. outPixel16 = (unsigned short*)tempData;

  73. inPixel32 = (unsigned int*)image->getData();

  75. for(unsigned int i = 0; i < length; ++i, ++inPixel32) { *outPixel16++ = ((((*inPixel32 >> 0) & 0xFF) >> 3) << 11) | // R ((((*inPixel32 >> 8) & 0xFF) >> 2) << 5) | // G ((((*inPixel32 >> 16) & 0xFF) >> 3) << 0); // B } } else { // Convert "RRRRRRRRRGGGGGGGGBBBBBBBB" to "RRRRRGGGGGGBBBBB" tempData = new unsigned char[width * height * 2]; outPixel16 = (unsigned short*)tempData; inPixel8 = (unsigned char*)image->getData();

  77. for(unsigned int i = 0; i < length; ++i) { *outPixel16++ = (((*inPixel8++ & 0xFF) >> 3) << 11) | // R (((*inPixel8++ & 0xFF) >> 2) << 5) | // G (((*inPixel8++ & 0xFF) >> 3) << 0); // B } } } else if (pixelFormat == kCCTexture2DPixelFormat_RGBA4444) { // Convert "RRRRRRRRRGGGGGGGGBBBBBBBBAAAAAAAA" to "RRRRGGGGBBBBAAAA" inPixel32 = (unsigned int*)image->getData();

  79. tempData = new unsigned char[width * height * 2];

  81. outPixel16 = (unsigned short*)tempData;

  83. for(unsigned int i = 0; i < length; ++i, ++inPixel32) { *outPixel16++ = ((((*inPixel32 >> 0) & 0xFF) >> 4) << 12) | // R ((((*inPixel32 >> 8) & 0xFF) >> 4) << 8) | // G ((((*inPixel32 >> 16) & 0xFF) >> 4) << 4) | // B ((((*inPixel32 >> 24) & 0xFF) >> 4) << 0); // A } } else if (pixelFormat == kCCTexture2DPixelFormat_RGB5A1) { // Convert "RRRRRRRRRGGGGGGGGBBBBBBBBAAAAAAAA" to "RRRRRGGGGGBBBBBA" inPixel32 = (unsigned int*)image->getData();

  85. tempData = new unsigned char[width * height * 2];

  87. outPixel16 = (unsigned short*)tempData;

  89. for(unsigned int i = 0; i < length; ++i, ++inPixel32) { *outPixel16++ = ((((*inPixel32 >> 0) & 0xFF) >> 3) << 11) | // R ((((*inPixel32 >> 8) & 0xFF) >> 3) << 6) | // G ((((*inPixel32 >> 16) & 0xFF) >> 3) << 1) | // B ((((*inPixel32 >> 24) & 0xFF) >> 7) << 0); // A } } else if (pixelFormat == kCCTexture2DPixelFormat_A8) { // Convert "RRRRRRRRRGGGGGGGGBBBBBBBBAAAAAAAA" to "AAAAAAAA" inPixel32 = (unsigned int*)image->getData();

  91. tempData = new unsigned char[width * height];

  93. unsigned char *outPixel8 = tempData;

  95. for(unsigned int i = 0; i < length; ++i, ++inPixel32) { *outPixel8++ = (*inPixel32 >> 24) & 0xFF; // A

  97. }

  99. }

  101. if (hasAlpha && pixelFormat == kCCTexture2DPixelFormat_RGB888)

  103. {

  105. // Convert "RRRRRRRRRGGGGGGGGBBBBBBBBAAAAAAAA" to "RRRRRRRRGGGGGGGGBBBBBBBB"

  107. inPixel32 = (unsigned int*)image->getData();

  109. tempData = new unsigned char[width * height * 3];

  111. unsigned char *outPixel8 = tempData;

  113. for(unsigned int i = 0; i < length; ++i, ++inPixel32) { *outPixel8++ = (*inPixel32 >> 0) & 0xFF; // R

  115. *outPixel8++ = (*inPixel32 >> 8) & 0xFF; // G

  117. *outPixel8++ = (*inPixel32 >> 16) & 0xFF; // B

  119. }

  121. }

  123. initWithData(tempData, pixelFormat, width, height, imageSize);

  125. if (tempData != image->getData())

  127. {

  129. delete [] tempData;

  131. }

  133. m_bHasPremultipliedAlpha = image->isPremultipliedAlpha();

  135. return true;

  137. }
复制代码

那么，在2dx中，我们也是可以这么处理的，首先看纹理中的一个函数：
这里面针对kCCTexture2DPixelFormat_RGB888像素格式的图片进行了这么的处理：

  1. *outPixel8++ = (*inPixel32 >> 0) & 0xFF; // R

  3. *outPixel8++ = (*inPixel32 >> 8) & 0xFF; // G

  5. *outPixel8++ = (*inPixel32 >> 16) & 0xFF; // B
复制代码



那么，我们就可以考虑在点击事件中处理这个透明区域的问题了，began事件如下：
  1. bool FDPixelSprite::ccTouchBegan(cocos2d::CCTouch *pTouch, cocos2d::CCEvent *pEvent)

  3. {

  5. if (this->isContainTouchLocation(pTouch) ) {

  7. ccColor4B c = {0, 0, 0, 0};

  9. CCSize winSize = CCDirector::sharedDirector()->getWinSize();

  11. CCPoint touchPoint = pTouch->getLocationInView();

  13. CCSize cSize = this->getContentSize();

  15. CCPoint pos(this->getPositionX() - cSize.width/2,winSize.height-this->getPositionY()- cSize.height/2);

  17. CCPoint localPoint = ccp(touchPoint.x - pos.x,

  19. touchPoint.y -pos.y);

  21. unsigned int x = localPoint.x, y = localPoint.y;

  23. unsigned char *data_ = this->getTexture()->getFDImageData();

  25. unsigned int *pixel = (unsigned int *)data_;

  27. pixel = pixel + (y * (int)this->getContentSize().width)* 1 + x * 1;

  29. c.r = *pixel & 0xff;

  31. c.g = (*pixel >> 8) & 0xff;

  33. c.b = (*pixel >> 16) & 0xff;

  35. c.a = (*pixel >> 24) & 0xff;

  37. if (c.a == 0) {

  39. CCLog("firedragonpzy:ccTouchBegan");

  41. return false;

  43. }else

  45. {

  47. return true;

  49. }

  51. }

  53. return false;

  55. }
复制代码



处理原理：
获取点击的像素，判断当前的a值是否为0，若为0，则是透明区域。
注意点：
图片的坐标原点在图片的左上角，这里大家需要做一下坐标的转化，把点击屏幕的坐标转化为相对于图像左上角的坐标即可。
关于图像，它的颜色表示分为：R、G、B、A四部分，各占八位。
代码中：*pixel >> (n)bit，为了得到单独的red,green,blue,alpha值，具体得到什么，目前不是很清楚，貌似什么进制【时间原因，改日谈……】不过可以给大家提供个例子。
网上例子(jdk)：
比如大红色用整数表示就是00 FF 00 00
pixel >> somebits是为了得到单独的alpha,red,green,blue值
右移24与255与操作得到alpha
16位得到red……
如果不& 0xff的话，上面的int green = (pixel >>  8) & 0xff;
得到的green值是FF 00 也就是65280，当然就不是我们要得到值
与操作是为了把高位削去!!!!
【因为pixel是一个整数
图像的表示分四部分：alpha值，red,green,blue
每一个值占一个字节，一个字节有8位二进制】
求解释……欢迎拍砖……
推荐阅读：http://www.cocos2d-x.org/boards/6/topics/3472
注意啦，注意啦，下面还有个赠送篇、、、、【产生赠送篇的缘由：一群友说如果设置了锚点，怎么处理啊，那代码起不是不对了，所以我又产生了赠送篇，不过使用精灵的时候，基本都是以(0.5,0.5)为锚点，我开始没考虑这问题是源于这，呵呵，假设你锚点不是(0.5,0.5)旋转什么的可能就……效果不好。不过既然有不是CCPointZero的需求，我就写了支持不同锚点的FDPixelSprite,不过建议大家使用针对锚点为(0.5,0.5)的，效率高……】
现在贴出我的FDPixelSprite，大家可以直接使用此精灵处理含有透明区域图片的点击问题：
FDPixelSprite.h
  1. //

  3. // FDPixelSprite.h

  5. // PixelDemo

  7. //

  9. // Created by firedragonpzy on 13-2-19.

  11. //

  13. //

  15. #ifndef __PixelDemo__FDPixelSprite__

  17. #define __PixelDemo__FDPixelSprite__

  19. #include "cocos2d.h"

  21. USING_NS_CC;

  23. class FDPixelSprite : public CCSprite, public CCTargetedTouchDelegate {

  25. public:

  27. FDPixelSprite();

  29. virtual ~FDPixelSprite();

  31. void onEnter();

  33. void onExit();

  35. static FDPixelSprite* create( const char *pszFileName );

  37. CCRect atlasRect();

  39. bool isContainTouchLocation(CCTouch *pTouch);

  41. bool ccTouchBegan(CCTouch *pTouch, CCEvent *pEvent);

  43. void ccTouchMoved(CCTouch *pTouch, CCEvent *pEvent);

  45. void ccTouchEnded(CCTouch *pTouch, CCEvent *pEvent);

  47. CC_SYNTHESIZE(const char*, m_pName,Name);

  49. };

  51. #endif /* defined(__PixelDemo__FDPixelSprite__) */
复制代码



FDPixelSprite.cpp
  1. //

  3. // FDPixelSprite.cpp

  5. // PixelDemo

  7. //

  9. // Created by firedragonpzy on 13-2-19.

  11. //

  13. //

  15. #include "FDPixelSprite.h"

  17. FDPixelSprite::FDPixelSprite()

  19. {}

  21. FDPixelSprite::~FDPixelSprite()

  23. {}

  25. FDPixelSprite* FDPixelSprite::create(const char *pszFileName)

  27. {

  29. FDPixelSprite *sprite = new FDPixelSprite();

  31. if (sprite && sprite->initWithFile(pszFileName)) {

  33. sprite->setName(pszFileName);

  35. sprite->autorelease();

  37. return sprite;

  39. }

  41. CC_SAFE_DELETE(sprite);

  43. sprite = NULL;

  45. return NULL;

  47. }

  49. void FDPixelSprite::onEnter()

  51. {

  53. CCSprite::onEnter();

  55. CCDirector::sharedDirector()->getTouchDispatcher()->addTargetedDelegate(this, 0, true);

  57. }

  59. void FDPixelSprite::onExit()

  61. {

  63. CCSprite::onExit();

  65. CCDirector::sharedDirector()->getTouchDispatcher()->removeDelegate(this);

  67. }

  69. bool FDPixelSprite::ccTouchBegan(cocos2d::CCTouch *pTouch, cocos2d::CCEvent *pEvent)

  71. {

  73. if (this->isContainTouchLocation(pTouch) ) {

  75. ccColor4B c = {0, 0, 0, 0};

  77. CCSize winSize = CCDirector::sharedDirector()->getWinSize();

  79. CCPoint touchPoint = pTouch->getLocationInView();

  81. CCSize cSize = this->getContentSize();

  83. CCPoint pos(this->getPositionX() - cSize.width/2,winSize.height-this->getPositionY()- cSize.height/2);

  85. CCPoint localPoint = ccp(touchPoint.x - pos.x,

  87. touchPoint.y -pos.y);

  89. unsigned int x = localPoint.x, y = localPoint.y;

  91. unsigned char *data_ = this->getTexture()->getFDImageData();

  93. unsigned int *pixel = (unsigned int *)data_;

  95. pixel = pixel + (y * (int)this->getContentSize().width)* 1 + x * 1;

  97. c.r = *pixel & 0xff;

  99. c.g = (*pixel >> 8) & 0xff;

  101. c.b = (*pixel >> 16) & 0xff;

  103. c.a = (*pixel >> 24) & 0xff;

  105. if (c.a == 0) {

  107. CCLog("firedragonpzy:ccTouchBegan");

  109. return false;

  111. }else

  113. {

  115. return true;

  117. }

  119. }

  121. return false;

  123. }

  125. void FDPixelSprite::ccTouchMoved(cocos2d::CCTouch *pTouch, cocos2d::CCEvent *pEvent)

  127. {

  129. CCPoint pos = this->getPosition();

  131. CCPoint sub = pTouch->getDelta();

  133. this->setPosition(ccpAdd(pos, sub));

  135. }

  137. void FDPixelSprite::ccTouchEnded(cocos2d::CCTouch *pTouch, cocos2d::CCEvent *pEvent)

  139. {

  141. CCLog("firedragonpzy:ccTouchEnded");

  143. }

  145. CCRect FDPixelSprite::atlasRect()

  147. {

  149. CCSize cSize = this->getContentSize();

  151. return CCRectMake(-cSize.width/2, -cSize.height/2, cSize.width, cSize.height);

  153. }

  155. bool FDPixelSprite::isContainTouchLocation(cocos2d::CCTouch *pTouch)

  157. {

  159. return this->atlasRect().containsPoint(convertTouchToNodeSpaceAR(pTouch));

  161. }
复制代码



————————————–赠送篇———————————————-
为什么产生赠送篇 ，上面已经解释的很清楚了，不废话了，开门见山：
改为适配不同锚点需要改动两个地方：
（一）：区域的判断：
  1. CCRect FDPixelSprite::atlasRect()

  3. {

  5. CCSize cSize = this->getContentSize();

  7. CCPoint point = this->getAnchorPointInPoints();

  9. return CCRectMake( -point.x, -point.y, cSize.width,cSize.height);

  11. }
复制代码



（二）相对于图片像素的转化
复制代码
  1. bool FDPixelSprite::ccTouchBegan(cocos2d::CCTouch *pTouch, cocos2d::CCEvent *pEvent)

  3. {

  5. if (this->isContainTouchLocation(pTouch) ) {

  7. ccColor4B c = {0, 0, 0, 0};

  9. CCSize winSize = CCDirector::sharedDirector()->getWinSize();

  11. CCPoint touchPoint = pTouch->getLocationInView();

  13. CCSize cSize = this->getContentSize();

  15. CCPoint point =this->getAnchorPointInPoints();

  17. point = ccp(cSize.width - point.x,cSize.height- point.y);

  19. CCPoint pos(this->getPositionX() - point.x,winSize.height-this->getPositionY()- point.y);

  21. CCPoint localPoint = ccp(touchPoint.x - pos.x,

  23. touchPoint.y -pos.y);

  25. unsigned int x = localPoint.x, y = localPoint.y;

  27. unsigned char *data_ = this->getTexture()->getFDImageData();

  29. unsigned int *pixel = (unsigned int *)data_;

  31. pixel = pixel + (y * (int)this->getContentSize().width)* 1 + x * 1;

  33. c.r = *pixel & 0xff;

  35. c.g = (*pixel >> 8) & 0xff;

  37. c.b = (*pixel >> 16) & 0xff;

  39. c.a = (*pixel >> 24) & 0xff;

  41. if (c.a == 0) {

  43. CCLog("firedragonpzy:ccTouchBegan----------");

  45. return false;

  47. }else

  49. {

  51. return true;

  53. }

  55. }

  57. return false;

  59. }
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