cocos2d-x 不规则图形碰撞检测

//判断有没有点到有材质的部分, p_point相对， CCSprite坐标
bool Tools::isClickTheRealSprite(cocos2d::CCSprite* p_sprite, const cocos2d::CCPoint p_point){
CCSize l_sizeInPixel = p_sprite->getContentSize();
//得到相对，Sprite左下的偏移
int l_iX = (int)(l_sizeInPixel.width/2.0f + p_point.x);
int l_iY = (int)(l_sizeInPixel.height/2.0f + (int)p_point.y);
CCPoint l_pointBL = ccp(l_iX, l_iY);
CCRect l_rect = CCRect(0, 0, l_sizeInPixel.width, l_sizeInPixel.height);
if(!(l_rect.containsPoint(l_pointBL))){
return false;
}

//开辟出空内存buffer
//unsigned char* l_buffer = (unsigned char*)malloc(l_sizeInPixel.width * l_sizeInPixel.height * 4);
//memset(l_buffer, 0, l_sizeInPixel.width * l_sizeInPixel.height * 4);
uint8_t l_buffer[4];

//写内存
CCSize size = p_sprite->getParent()->getContentSize();
CCRenderTexture* l_renderTexture = CCRenderTexture::create(l_sizeInPixel.width, l_sizeInPixel.height, kCCTexture2DPixelFormat_RGBA8888);
//l_renderTexture->begin();
l_renderTexture->beginWithClear(0, 0, 0, 0);
p_sprite->draw();
glReadPixels(l_pointBL.x, l_pointBL.y, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, l_buffer);
l_renderTexture->end();
//透明度
//int l_iValue_A = l_buffer[4*(int)(l_pointBL.y*l_sizeInPixel.width + l_pointBL.x)+3];
int l_iValue_A = l_buffer[3];
//free(l_buffer);
if(l_iValue_A < 5 ){
return false;
}
return true;
}