仅在释放模式下使用glGenBuffer的未处理异常-QT [英] Unhandled Exception using glGenBuffer on Release mode only - QT

问题描述

在Windows 7上使用发布模式下的Qt 4.8编译项目时遇到麻烦.在Debug上一切正常，但是在Release上，出现未处理的异常:0xC0000005:访问冲突.

I'm having some trouble while compiling my project on Windows 7 using Qt 4.8 on Release mode. Everything works fine on Debug, but on Release I get an Unhandled Exception: 0xC0000005: Access violation.

我将其范围缩小到发生这种情况的那一行，也就是我生成像素缓冲区的那一行. 我的第一个猜测是错误的DLL加载，但是我用Dependency Walker检查了可执行文件，并且每个DLL加载都正确.

I narrowed it down to the line where this happens, which is when I generate my Pixel Buffers. My first guess would be wrong DLLs loading, but I checked the executable with Dependency Walker and every DLL loaded is correct.

这是我的一些代码:

class CameraView : public QGLWidget, protected QGLFunctions;
void CameraView::initializeGL()
{

    initializeGLFunctions(this->context());

    glGenBuffers(1, &pbo_); //<<<<<  This is where I get the unhandled exception on Release mode
        glBindBuffer(QGLBuffer::PixelUnpackBuffer, pbo_);
        glBufferData(QGLBuffer::PixelUnpackBuffer, 3 * sizeof(BYTE) * image_width_ * image_height_, NULL, GL_STREAM_DRAW);
        ...
}

同样，这在调试时效果很好.为什么这只会在Release上发生?

Again, this works great on debug. Why would this only happen on Release?

推荐答案

我明白了. 似乎此问题与此相关: https://forum. qt.io/topic/12492/qt-4-8-qglfunctions-functions-crash-in-release-build

I got it. Seems like this issue is related to this one: https://forum.qt.io/topic/12492/qt-4-8-qglfunctions-functions-crash-in-release-build

，并且存在一个错误报告，该错误报告还可能与相关: https://bugreports.qt.io/browse/QTBUG-5729

and there's a bug report that may be related also: https://bugreports.qt.io/browse/QTBUG-5729

也许initializeGLFunctions()方法没有获取GL扩展函数的所有函数指针，我真的不知道为什么，但是看起来确实如此.

Perhaps the initializeGLFunctions() method is not getting all function pointers for the GL extension functions, I don't really know why but this seems to be it.

对我来说，解决方案是停止使用Qt的GL扩展，开始使用glew.

The solution for me was to stop using Qt's GL extensions and start using glew.

所以，这对我有用:

#include <QtGui/QtGui>
#include <gl/glew.h>
#include <QtOpenGL/QGLWidget>

class CameraView : public QGLWidget;
void CameraView::initializeGL()
{

   //initializeGLFunctions(this->context());
   GLenum init = glewInit();


   // Create buffers
   glGenBuffers(1, &pbo_);

   glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pbo_);
   glBufferData(GL_PIXEL_UNPACK_BUFFER, 3 * sizeof(BYTE) * image_width_ * image_height_, NULL, GL_STREAM_DRAW);

   // Set matrixes
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();

   glOrtho(0, this->width(), 0, this->height(), 0, 1);
   glClearColor(0.0, 0.0, 0.0, 0.0);
   glShadeModel(GL_FLAT);
   glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
}

请确保在所有QTOpenGL标头之前包含glew.h，否则会出现编译错误.

Be sure that glew.h is included before any QTOpenGL headers or else you'll get a compilation error.

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