Drawing QWidget over QGLNode in QGLView

Question

I use Qt3D and draw a complex 3d scene using QGLView.

I need to draw some widgets on QGLNode inside this scene, but I don't know how.

Here is a minimal example (based on "nesting" demo from qt3d) of what I suppose to do:

Header:

class CubeView : public QGLView
{
    Q_OBJECT
    Q_PROPERTY(qreal cubeAngle READ cubeAngle WRITE setCubeAngle)

public:
    CubeView(QWidget *parent = 0);
    ~CubeView();

    qreal cubeAngle() const { return cangle; }
    void setCubeAngle(qreal angle) { cangle = angle; update(); }

protected:
    void initializeGL(QGLPainter *painter);
    void paintGL(QGLPainter *painter);

private:
    QGLSceneNode *scene;
    QGLSceneNode *cube;
    QGLFramebufferObject *fbo;
    QGLFramebufferObjectSurface fboSurface;
    QGLCamera *innerCamera;
    qreal cangle;

    void drawCube(QGLPainter* painter);
    void drawFrameBuffer();
};

Initializing:

void CubeView::initializeGL(QGLPainter *)
{
    fbo = new QGLFramebufferObject(512, 512);
    fboSurface.setFramebufferObject(fbo);
}

Paint code:

void CubeView::paintGL(QGLPainter *painter)
{
    painter->modelViewMatrix().push();
    painter->projectionMatrix().push();

#ifdef DRAW_GLNODE
    painter->pushSurface(&fboSurface);
#endif

    painter->setCamera(innerCamera);
    painter->modelViewMatrix().rotate(cangle, 0.0f, 1.0f, 0.0f);

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

#ifdef DRAW_GLNODE
    cube->draw(painter);
#else
    QPushButton button;
    button.resize(fbo->width(), fbo->height());
    button.render(fbo); // filling QGLFrameBuffer
#endif

    drawFrameBuffer(); // debug QPixmap with QGLFrameBuffer data

#ifdef DRAW_GLNODE
    painter->popSurface();
#endif

    painter->projectionMatrix().pop();
    painter->modelViewMatrix().pop();

    drawCube(painter);
}

Drawing cube:

void CubeView::drawCube(QGLPainter *painter)
{
    painter->modelViewMatrix().push();

    painter->modelViewMatrix().rotate(cangle, 1.0f, 1.0f, 1.0f);

    painter->setStandardEffect(QGL::LitDecalTexture2D);

    glBindTexture(GL_TEXTURE_2D, fbo->texture());
    glEnable(GL_TEXTURE_2D);

    cube->draw(painter);

    glBindTexture(GL_TEXTURE_2D, 0);
    glDisable(GL_TEXTURE_2D);

    painter->modelViewMatrix().pop();
}

When "#define DRAW_GLNODE" is active it shows rotating cube as a texture inside another cube (you can see frame buffer data in the left window).

https://i.stack.imgur.com/Ok4NT.png

When I switch to "#define 0" it shows black screen in a QGLView, but QGLFrameBuffer contains data as you can see.

https://i.stack.imgur.com/5R6Wz.png

What am I doing wrong?

Drawing QWidget over QGLNode in QGLView

0 Answers0