stdRefInThread

1 std::thread传入引用值需要使用std::ref

std::ref的说明： Constructs an object of the appropriate reference_wrapper type to hold a reference to elem.
其实主要是，如果要向thread传参的时候，该参数在线程内会被修改，需要用这个ref作为一个wrapper将对象包裹成为一个引用然后传入。

void main() {

    while(1){
        ...<省略>...
        if (!initializedFlag) {
            initializedFlag = true;
            // viewThd = new std::thread(viewThread, camVecToDraw); // wrong way
            viewThd = new std::thread(viewThread, std::ref(camVecToDraw)); // right way
        }
        ...<省略>...

        addCamToDrawVec(imgData.image, camVecToDraw);
        camVecToDraw;
    }
    
    viewThd.join();
    delete viewThd;
    viewThd = nullptr;
}

void viewThread(std::vector<pangolin::OpenGlMatrix>& camVecToDraw) {
    while(!shallQuit()) {
        // render some cameras according to camVecToDraw
        ...<省略>...
    }
}