Qt produces OpenGl ES error

[fastcoder]

I made a small graphics engine to render objects and it uses paintGL function of QOpenGLWidget. However some 3D models cause error at the very first draw call d_ptr->f.DrawElements(mode, count, type, indices) as bad memory access. During the loading of these objects there is not any single GL error, buffers are all created fine. In addition if I trigger my model importing function from QT mousePressEvent callback everything works fine. It only happens if the model loading function is triggered from a menu bar item with QAction. Also these code and the same models run fine in Android,IOS and some windows platforms while have problem with some other Windows platforms and OSx. I suspect it is something to do with the GL context.

Here is my MainWindow and QOpenGLWidget for your reference.

// MainGlWidget.cpp


#include <QtWidgets>
#include <QtOpenGL>
#include "MainGlWidget.h"
#include "iostream"
#include "Common.h"
#ifdef __APPLE__
#include <unistd.h>
#endif // 


/*#include "Common.h"
#include "UltimateDesign.h"*/

MainGlWidget::MainGlWidget(QWidget *parent)
: QOpenGLWidget(parent)
{
    xRot = 0;
    yRot = 0;
    zRot = 0;

}
MainGlWidget::~MainGlWidget()
{
}

QSize MainGlWidget::minimumSizeHint() const
{
    return QSize(50, 50);
}

QSize MainGlWidget::sizeHint() const
{
    return QSize(400, 400);
}

static void qNormalizeAngle(int &angle)
{
    while (angle < 0)
        angle += 360 * 16;
    while (angle > 360)
        angle -= 360 * 16;
}

void MainGlWidget::setXRotation(int angle)
{
    qNormalizeAngle(angle);
    if (angle != xRot) {
        xRot = angle;
        emit xRotationChanged(angle);

    }

}

void MainGlWidget::setYRotation(int angle)
{
    qNormalizeAngle(angle);
    if (angle != yRot) {
        yRot = angle;
        emit yRotationChanged(angle);
    }
}

void MainGlWidget::setZRotation(int angle)
{
    qNormalizeAngle(angle);
    if (angle != zRot) {
        zRot = angle;
        emit zRotationChanged(angle);
    }
}
void MainGlWidget::importFile(std::string file)
{
  // When a QAction triggeres this function, for some models I have the mentioned problem
   makeCurrent();
   application->importFile(file); 
}

void MainGlWidget::initializeGL()
{

    CHECK_GL(glEnable(GL_DEPTH_TEST));
    CHECK_GL(glEnable(GL_CULL_FACE));

   //CHECK_GL(glCullFace(GL_CULL_FACE));
    //glCullFace(GL_BACK);
    CHECK_GL(glShadeModel(GL_SMOOTH));
    CHECK_GL(glEnable(GL_LIGHTING));
    CHECK_GL(glEnable(GL_LIGHT0));
    CHECK_GL(glClearColor(0.4, 0.4, 0.4, 1));
    CHECK_GL(glEnable(GL_BLEND));
    CHECK_GL(glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA));
    CHECK_GL(glDepthMask(GL_TRUE));
#ifdef WIN32
	//glViewport(0, 0, 1280, 960);
#endif
    application->init((QOpenGLWidget*)this);
    application->setScreenDimentions(width(),height());

#ifdef WIN32
	CreateThread(
		NULL,                   // default security attributes
		0,                      // use default stack size
		timer,       // thread function name
		(void*) this,          // argument to thread function
		0,                      // use default creation flags
		NULL);  // returns the thread identifier
#elif __linux__ || __APPLE__
	pthread_t thread;
	pthread_create(&thread, NULL, timer, 	(void*) this);
#endif

}

void MainGlWidget::paintGL()
{

    GLint m_viewport[4];
    glGetIntegerv( GL_VIEWPORT, m_viewport );
    CHECK_GL(glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT));
    application->render("cam1");
}

void MainGlWidget::resizeGL(int width, int height)
{
	std::cout << "width" << width << std::endl;
	std::cout << "height" << height << std::endl;
     size[0] = width;
     size[1] = height;
#ifndef DRONE
    int side = qMin(size[0], size[1]);
    glViewport((size[0]-side)/2,(size[1]-side)/2, side, side);
#endif
    update();
}

void MainGlWidget::mousePressEvent(QMouseEvent *event)
{
    lastPos = event->pos();
    if (event->buttons() & Qt::LeftButton) {
    application->mouseClickWithLeft(lastPos.x(),lastPos.y());
    }else if (event->buttons() & Qt::RightButton) {
        application->mouseClickWithRight(lastPos.x(),lastPos.y());
    }

}

void MainGlWidget::mouseMoveEvent(QMouseEvent *event)
{
//if I import the model in this call back function then it works fine with all models.
//    application->importFile(file); 


    int dx = event->x() - lastPos.x();
    int dy = event->y() - lastPos.y();
    lastPos = event->pos();
    if (event->buttons() & Qt::LeftButton) {
        setXRotation(xRot + dy);
        setYRotation(yRot + dx);
        application->mouseDragWithLeft(dx,dy);
    } else if (event->buttons() & Qt::RightButton) {
        setXRotation(xRot + 8 * dy);
        setZRotation(zRot + 8 * dx);
        application->mouseDragWithRight(dx,dy);
    }else if (event->buttons() &Qt::MiddleButton) {
        setXRotation(xRot + 8 * dy);
        setZRotation(zRot + 8 * dx);
        application->mouseDragWithMiddle(dx,dy);
    }

}

void MainGlWidget::draw()
{

}
#ifdef WIN32

DWORD WINAPI timer(LPVOID lpParam)
{
	MainGlWidget* glwidget = (MainGlWidget*)lpParam;

	while (true)
	{

		glwidget->update();

		Sleep(10);
	}


}
#elif __linux__ || __APPLE__

void *timer(void *lpParam)
{
	MainGlWidget* glwidget = (MainGlWidget*)lpParam;

	while (true)
	{
        std::cout<<"loop "<<pthread_self();

		glwidget->update();
        usleep(16000);

	}

}
#endif
//=======================================================================
//MainWindow.cpp
void MainWindowMVM::createActions()
{
    
    importAct = new QAction( tr("&Import Model"), this);
    importAct->setShortcuts(QKeySequence::Open);
    importAct->setStatusTip(tr("Please open a model"));
    connect(importAct, SIGNAL(triggered()), this, SLOT(import()));


}
void MainWindowMVM::createMenus()
{
  fileMenu=menuBar()->addMenu(tr("&File"));
  fileMenu->addAction(importAct);
}

void MainWindowMVM::import()
{
        QString fileName = QFileDialog::getOpenFileName(this);
        std::string file = fileName.toUtf8().constData();
        ui->MainScreen->importFile(file);  //MainScreen keeps the instance of MainGlWidget class above.
}