在第二个线程上加载OpenGL资源

Question

我在OpenGL 2.1中使用win32线程.我想要实现的是渲染简单的图像说"加载",而在后台整个3D场景正在加载.它现在有效,但我有一个问题,有时我的立方体贴图纹理的一部分从Mozilla Firefox浏览器中获取数据(如何发生这种情况???)并忽略那个带有纹理的小盒子,它只是一个精灵和它应该在哪里:

这种情况发生在我尝试加载程序时的三分之一.这是我的线程的样子:

WindowsThread::WindowsThread(HGLRC graphicsContext, HDC deviceContext) :
    graphicsContext_(graphicsContext),
    deviceContext_(deviceContext),
    running_(false),
    task_(0),
    mode_(WT_NORMAL)
{
    handle_ = CreateThread(0, 0,
        (unsigned long (__stdcall *)(void *)) this->staticRun,
        (void*) this, CREATE_SUSPENDED, &id_);

    if (handle_ == 0) {
        LOGE("Unable to create thread.");
        return;
    }

    if (!SetThreadPriority(handle_, THREAD_PRIORITY_NORMAL)) {
        LOGE("Unable to set thread priority for thread.");
        return;
    }
}

WindowsThread::~WindowsThread() {
    finishTask();
    running_ = false;
    WaitForSingleObject(handle_, INFINITE);
    CloseHandle(handle_);
    wglDeleteContext(graphicsContext_);
}

void WindowsThread::start() {
    running_ = true;
    if (!ResumeThread(handle_)) {
        LOGW("Unable to resume thread.");
    }
}

bool WindowsThread::isRunning() {
    return running_;
}

void WindowsThread::setTask(Task* task, Mode mode) {
    finishTask();
    task_ = task;
    mode_ = mode;
}

bool WindowsThread::hasTask() {
    return task_ != 0;
}

void WindowsThread::finishTask() {
    while (task_ != 0) {
        Sleep(1);
    }
}

void WindowsThread::stop() {
    running_ = false;
}

int WindowsThread::staticRun(void* thread) {
    return ((WindowsThread*) thread)->run();
}

int WindowsThread::run() {
    wglMakeCurrent(deviceContext_, graphicsContext_);
    while (running_) {
        if (task_ != 0) {
            task_->run();
            task_ = 0;
        }
        Sleep(10);
    }
    wglMakeCurrent(0, 0);
    return 1;
}

ThreadManager:

WindowsThreadManager::WindowsThreadManager(
    System* system, UINT threadPoolSize)
{
    if (threadPoolSize == 0) {
        SYSTEM_INFO info;
        GetSystemInfo(&info);
        threadPoolSize = info.dwNumberOfProcessors;
        if (threadPoolSize == 0) {
            threadPoolSize = 1;
        }
    }
    LOGI("Number of threads used: %d", threadPoolSize);
    masterContext_ = wglGetCurrentContext();
    HDC hdc = wglGetCurrentDC();
    for (UINT i = 0; i < threadPoolSize; i++) {
        HGLRC threadContext = wglCreateContext(hdc);
        wglShareLists(masterContext_, threadContext);
        WindowsThread* thread = new WindowsThread(threadContext, hdc);
        thread->start();
        threads_.push_back(thread);
    }
}

WindowsThreadManager::~WindowsThreadManager() {
    for (UINT i = 0; i < threads_.size(); i++) {
        delete threads_[i];
    }
    for (UINT i = 0; i < tasks_.size(); i++) {
        delete tasks_[i];
    }
}

void WindowsThreadManager::execute(Task* task, Mode mode) {
    WindowsThread::Mode wtMode = WindowsThread::WT_NORMAL;
    if (mode == TM_GRAPHICS_CONTEXT) {
        wtMode = WindowsThread::WT_GRPAHICS_CONTEXT;
    }
    tasks_.push_back(task);
    for (UINT i = 0; i < threads_.size(); i++) {
        if (!threads_[i]->hasTask()) {
            threads_[i]->setTask(task, wtMode);
            return;
        }
    }
    threads_[0]->setTask(task, wtMode);
}

void WindowsThreadManager::joinAll() {
    for (UINT i = 0; i < threads_.size(); i++) {
        if (threads_[i]->hasTask()) {
            threads_[i]->finishTask();
        }
    }
}

我在Winodws 8上使用Nvidia 670GTX和最新的驱动程序.问题可能出在哪里？

[编辑]我在我的加载程序线程的末尾添加了glFinish(),现在一切都正常加载.我在某个地方红了,OpenGL没有立即完成它的所有工作,所以我猜这就是这种情况,其中上下文在它完成它的工作之前被设置为NULL.

Answer 1

它现在有效,但我有一个问题,有时我的立方体贴图纹理的一部分从Mozilla Firefox浏览器中获取数据(这到底怎么回事？)

您的纹理从未初始化的图形内存接收数据,该内存很可能包含先前使用该内存区域的另一个进程的残留图像.如果这样的事情会发生

a)驱动程序有一个错误,并且不会在线程之间同步资源

和

b)如果你正在尝试修改纹理,那么它被绑定到另一个线程中的纹理单元.

编辑:您可以(并且应该)自己引入适当的同步.仅仅因为它提高了性能.当纹理当前不忙时,使用条件变量在线程之间进行通信.理想情况下,您使用两个或更多纹理,您以循环方式更新.