Display Sample 6 in a Qt Widget

Gaming and Visualization Technologies Visualization OptiX
1

What is the best way to display sample 6 of the OptiX SDK in a Qt widget? Should I change GLUTDisplay to render into the widget?

Is there a way to use the vertex buffer object from GLUTDisplay and render it into a QWindow or QGLWidget?

2

I would recommend you to use QGLWidget. It does have several GLUT equivalent functions already inbuilt in it.

3

I created a new widget based on the graphicsview. There I have a function “drawBuffer” which reads a buffer, creates the colors and writes them to an image:

// map buffer
float3* mapped_buffer = reinterpret_cast<float3*>( m_buffer->get()->map() );

// create pixmap
m_image = new QImage(width, height, QImage::Format_RGB888);

// convert data to values between 0 and 255 and put it into image object
for (unsigned int x = 0; x < width; ++x) {
    for(unsigned int y = 0; y < height; ++y) {
        int i_w = y*width + x;
        QRgb color = qRgb((int)(mapped_buffer[i_w].x*255),
                     (int)(mapped_buffer[i_w].y*255),
                     (int)(mapped_buffer[i_w].z*255));
        m_image->setPixel(x, y, color);
    }
}

// unmap buffer
m_buffer->get()->unmap();

The last step is to add the image to a scene which could be set to the graphicsview.

4

Yes, the above posts are correct: QGLWidget is what you’re searching for.

You can subclass this and override

  • paintGL() - this is the function where the openGL scene is rendered and where most of the widget’s code resides
  • resizeGL() - called whenever the widget is resized
  • initializeGL() - sets up an openGL rendering context, called once before paintGL or resizeGL

An example Qt app with a QGLWidget

5

I am using Qt5 and it seems to me that QGLWidget should not be used for new code. Is this correct? I have read ( OpenGL in Qt 5.1 - Part 1 - KDAB ) that it is better to use a QOpenGLContext and QWindow with Qt5.

6

Looking to my post from yesterday, you see that there is no GL needed:

My code shows the equivalent for the “paintGL()”. It easy to replace the “resizeGL()” by using the QGraphicsView signals, too.

7

It depends on what you need to do, QGLWidget is fairly simple and takes care of the window if you don’t have one (http://qt-project.org/doc/qt-5.0/qtopengl/qglwidget.html#details), otherwise you can use QOpenGLContext to just use a native openGL context/reuse a context (i.e. you do the window handling by yourself) (http://qt-project.org/doc/qt-5.0/qtgui/qopenglcontext.html#details)

8

I am having issues to display sample6 in a QGLWidget. All I need to do take the outputbuffer from the Meshviewer and create an image, right?
When I use the method RoboMod uses most of the coordinates dont get the right value and if I save the QImage the picture looks weird, but if I use the function from sutil to save the picture in a .ppm file, the image seems to be right.

So can somebody give me a hint of to construct the paintGL() in order to render the scene?

9

Constructing the QImage directly with its constructor I get the right image

uchar* data = (uchar *)m_outputBuffer->map();
QImage img(data, m_width, m_height, QImage::Format_ARGB32);
// or maybe Format_RGBA8888 would work for you.. you have to check docs 
m_outputBuffer->unmap();
img.save("optixSampleSix.png","PNG");