c++ - 不能使用外部 QOpenGLWidget 制作的上下文吗？

Question

调试时的确切崩溃是:

The inferior stopped because it triggered an exception. Stopped in thread 0 by: Exception at 0x7fed96c6cda, code: 0x0000005: read access violation at: 0x0, flags=0x0.

然后异常指向下面代码中的这一行:

if(QOpenGLContext::currentContext()->isValid())

下面的代码足以为我重现异常。子类化 QOpenGLWidget 类并在尝试访问上下文之前让子类调用一次 initializeGL() 并不能解决问题。

#include <QApplication>
#include <QOpenGLWidget>
#include <QOpenGLContext>
#include <QDebug>

void initialize(QOpenGLWidget * renderArea)
{
    renderArea->makeCurrent();
    if(QOpenGLContext::currentContext()->isValid())
    {
        qInfo() << "Valid.";
    }
}

int main(int argc, char *argv[])
{
    QSurfaceFormat format;
    format.setVersion(3,3);
    format.setProfile(QSurfaceFormat::CoreProfile);
    QSurfaceFormat::setDefaultFormat(format);

    QApplication a(argc, argv);

    QOpenGLWidget * glw = new QOpenGLWidget;
    initialize(glw);

    return a.exec();
}

Answer 1

我现在明白了答案:您必须在事件循环开始后进行所有此类 opengl 初始化。

“MainWindow”类在接收信号“onEventLoopStarted”时执行所有 opengl 初始化的固定代码:

#include "mainwindow.h"
#include <QApplication>
#include <QOpenGLWidget>
#include <QOpenGLContext>
#include <QDebug>
#include <QTimer>

int main(int argc, char *argv[])
{
    QSurfaceFormat format;
    format.setVersion(3,3);
    format.setProfile(QSurfaceFormat::CoreProfile);
    QSurfaceFormat::setDefaultFormat(format);

    QApplication a(argc, argv);

    MainWindow w;
    w.resize(512, 512);
    w.show();

    QTimer::singleShot(0, &w, SLOT(onEventLoopStarted()));

    return a.exec();
    //Window receives event and begins to initialize.
}