How to share textures between QGLWidgets

I am currently having problems sharing texture objects between several (currently two) different QGLWidgets. I first create a custom QGLWidget and I override its initializeGL() function and do texture initialization in there. Here is the following code:

Code:

---

SharedGLWidget::SharedGLWidget(QWidget *parent) :
    QGLWidget(QGLFormat(QGL::DoubleBuffer | QGL::Rgba | QGL::DepthBuffer), parent)
{
}
 
void SharedGLWidget::initializeGL()
{
    GLbyte *pBytes;
    GLint iWidth, iHeight, iComponents;
    GLenum eFormat;
 
    // Load texture
    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    pBytes = gltLoadTGA("../SharedTest/stone.tga", &iWidth, &iHeight, &iComponents, &eFormat);
    glTexImage2D(GL_TEXTURE_2D, 0, iComponents, iWidth, iHeight, 0, eFormat, GL_UNSIGNED_BYTE, pBytes);
    free(pBytes);
 
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 
    glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
    glEnable(GL_TEXTURE_2D);
}

---

Then I create a second QGLWidget and do normal Qt rendering stuff with the exception of loading the textures again.

Code:

---

GLWidget::GLWidget(QWidget *parent, const QGLWidget *sharedWidget, Qt::WindowFlags f)
    : QGLWidget(QGLFormat(QGL::DoubleBuffer | QGL::Rgba | QGL::DepthBuffer), parent, sharedWidget, f)
    , xRot(0.0f)
    , yRot(0.0f)
{
}
 
void GLWidget::initializeGL()
{
    // Light values and coordinates
    GLfloat  whiteLight[] = { 0.05f, 0.05f, 0.05f, 1.0f };
    GLfloat  sourceLight[] = { 0.25f, 0.25f, 0.25f, 1.0f };
    GLfloat	 lightPos[] = { -10.f, 5.0f, 5.0f, 1.0f };
 
    glEnable(GL_DEPTH_TEST);	// Hidden surface removal
    glFrontFace(GL_CCW);		// Counter clock-wise polygons face out
    glEnable(GL_CULL_FACE);		// Do not calculate inside of jet
 
    // Enable lighting
    glEnable(GL_LIGHTING);
 
    // Setup and enable light 0
    glLightModelfv(GL_LIGHT_MODEL_AMBIENT,whiteLight);
    glLightfv(GL_LIGHT0,GL_AMBIENT,sourceLight);
    glLightfv(GL_LIGHT0,GL_DIFFUSE,sourceLight);
    glLightfv(GL_LIGHT0,GL_POSITION,lightPos);
    glEnable(GL_LIGHT0);
 
    // Enable color tracking
    glEnable(GL_COLOR_MATERIAL);
 
    // Set Material properties to follow glColor values
    glColorMaterial(GL_FRONT, GL_AMBIENT_AND_DIFFUSE);
 
    // Black blue background
    glClearColor(0.0f, 0.0f, 0.0f, 1.0f );
 
    glEnable(GL_TEXTURE_2D);
}
 
void GLWidget::paintGL()
{
    M3DVector3f vNormal;
    M3DVector3f vCorners[5] = { { 0.0f, .80f, 0.0f },     // Top           0
                              { -0.5f, 0.0f, -.50f },    // Back left     1
                              { 0.5f, 0.0f, -0.50f },    // Back right    2
                              { 0.5f, 0.0f, 0.5f },      // Front right   3
                              { -0.5f, 0.0f, 0.5f }};    // Front left    4
 
    // Clear the window with current clearing color
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
    // Save the matrix state and do the rotations
    glPushMatrix();
        // Move object back and do in place rotation
        glTranslatef(0.0f, -0.25f, -4.0f);
        glRotatef(xRot, 1.0f, 0.0f, 0.0f);
        glRotatef(yRot, 0.0f, 1.0f, 0.0f);
 
        // Draw the Pyramid
        glColor3f(1.0f, 1.0f, 1.0f);
        glBegin(GL_TRIANGLES);
            // Bottom section - two triangles
            glNormal3f(0.0f, -1.0f, 0.0f);
            glTexCoord2f(1.0f, 1.0f);
            glVertex3fv(vCorners[2]);
 
            glTexCoord2f(0.0f, 0.0f);
            glVertex3fv(vCorners[4]);
 
            glTexCoord2f(0.0f, 1.0f);
            glVertex3fv(vCorners[1]);
 
 
            glTexCoord2f(1.0f, 1.0f);
            glVertex3fv(vCorners[2]);
 
            glTexCoord2f(1.0f, 0.0f);
            glVertex3fv(vCorners[3]);
 
            glTexCoord2f(0.0f, 0.0f);
            glVertex3fv(vCorners[4]);
 
            // Front Face
            m3dFindNormal(vNormal, vCorners[0], vCorners[4], vCorners[3]);
            glNormal3fv(vNormal);
            glTexCoord2f(0.5f, 1.0f);
            glVertex3fv(vCorners[0]);
            glTexCoord2f(0.0f, 0.0f);
            glVertex3fv(vCorners[4]);
            glTexCoord2f(1.0f, 0.0f);
            glVertex3fv(vCorners[3]);
 
            // Left Face
            m3dFindNormal(vNormal, vCorners[0], vCorners[1], vCorners[4]);
            glNormal3fv(vNormal);
            glTexCoord2f(0.5f, 1.0f);
            glVertex3fv(vCorners[0]);
            glTexCoord2f(0.0f, 0.0f);
            glVertex3fv(vCorners[1]);
            glTexCoord2f(1.0f, 0.0f);
            glVertex3fv(vCorners[4]);
 
            // Back Face
            m3dFindNormal(vNormal, vCorners[0], vCorners[2], vCorners[1]);
            glNormal3fv(vNormal);
            glTexCoord2f(0.5f, 1.0f);
            glVertex3fv(vCorners[0]);
 
            glTexCoord2f(0.0f, 0.0f);
            glVertex3fv(vCorners[2]);
 
            glTexCoord2f(1.0f, 0.0f);
            glVertex3fv(vCorners[1]);
 
            // Right Face
            m3dFindNormal(vNormal, vCorners[0], vCorners[3], vCorners[2]);
            glNormal3fv(vNormal);
            glTexCoord2f(0.5f, 1.0f);
            glVertex3fv(vCorners[0]);
            glTexCoord2f(0.0f, 0.0f);
            glVertex3fv(vCorners[3]);
            glTexCoord2f(1.0f, 0.0f);
            glVertex3fv(vCorners[2]);
        glEnd();
 
 
    // Restore the matrix state
    glPopMatrix();
 
    // Buffer swap
    swapBuffers();
}

---

In my main.cpp I pass the first QGLWidget with just the texture initialization as the sharedWidget for the second QGLWidget:

Code:

---

int main(int argc, char* argv[])
{
    QApplication app(argc, argv);
 
    SharedGLWidget* glwidget1 = new SharedGLWidget;
 
    GLWidget* widget = new GLWidget(0, glwidget1);
    widget->show();
 
    app.exec();
}

---

I am not sure what I am missing but when widget is shown the texture isn't showing up (the pyramid is drawn but with no texturing). I am wondering what I am missing and if anyone has any idea as to how I can do this. I am only creating one texture object thus I was trying to not use glGenBuffers for texture objects but if this is something that has to be done I will try to do it while I wait for some responses. I am curious if I do go that route, how the glBind call would be preformed in the rendering widget. Thanks for any help!

I did find one potential issue, but it didn't resolve my problem. I moved all of the initializeGL() calls from the shared widget to the constructor because I forgot that initializeGL() is only called before paintGL is called and not called at all if sharedwidget->show() isn't called. However this didn't solve my problem :(

You can share texture object use GLwidget construct function ,
QGLWidget::QGLWidget ( QWidget * parent = 0, const QGLWidget * shareWidget = 0, Qt::WindowFlags f = 0 ),it will share texture object with shareWidget.But I want share texture object with multi qglwidget ,