QGLWidget - distortion occured - qt

Question

I would like to display sample6 of the OptixSDK in a QGLWidget.
My application has only 3 QSlider for the rotation around the X,Y,Z axis and the QGLWidget.
For my understanding, paintGL() gets called whenever updateGL() is called by my QSlider or Mouseevents. Then I initialize a rotation matrix and apply this matrix to the PinholeCamera in order to trace the scene with new transformed cameracoordinates, right?
When tracing is finished i get the outputbuffer and use it draw the pixels with glDrawPixels(), just like in GLUTdisplay.cpp given in the OptiX framework.
But my issue is that the image is skewed/distorted. For example I wanted to display a ball, but the ball is extremley flatened, but the rotation works fine.
When I am zooming out, it seems that the Image scales much slower horizontally than vertically.
I am almost sure/hope that it has to do something with the gl...() functions that are not used properly. What am I missing? Can someone help me out?
For the completeness i post my paintGL() and updateGL() code.
void MyGLWidget::initializeGL()
{
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
m_scene = new MeshViewer();
m_scene->setMesh( (std::string( sutilSamplesDir() ) + "/ball.obj").c_str());
int buffer_width, buffer_height;
// Set up scene
SampleScene::InitialCameraData initial_camera_data;
m_scene->setUseVBOBuffer( false );
m_scene->initScene( initial_camera_data );
int m_initial_window_width = 400;
int m_initial_window_height = 400;
if( m_initial_window_width > 0 && m_initial_window_height > 0)
m_scene->resize( m_initial_window_width, m_initial_window_height );
// Initialize camera according to scene params
m_camera = new PinholeCamera( initial_camera_data.eye,
initial_camera_data.lookat,
initial_camera_data.up,
-1.0f, // hfov is ignored when using keep vertical
initial_camera_data.vfov,
PinholeCamera::KeepVertical );
Buffer buffer = m_scene->getOutputBuffer();
RTsize buffer_width_rts, buffer_height_rts;
buffer->getSize( buffer_width_rts, buffer_height_rts );
buffer_width = static_cast<int>(buffer_width_rts);
buffer_height = static_cast<int>(buffer_height_rts);
float3 eye, U, V, W;
m_camera->getEyeUVW( eye, U, V, W );
SampleScene::RayGenCameraData camera_data( eye, U, V, W );
// Initial compilation
m_scene->getContext()->compile();
// Accel build
m_scene->trace( camera_data );
m_scene->getContext()->launch( 0, 0 );
// Initialize state
glMatrixMode(GL_PROJECTION);glLoadIdentity();glOrtho(0, 1, 0, 1, -1, 1 );
glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glViewport(0, 0, buffer_width, buffer_height);
}
And here is paintGL()
void MyGLWidget::paintGL()
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
float3 eye, U, V, W;
m_camera->getEyeUVW( eye, U, V, W );
SampleScene::RayGenCameraData camera_data( eye, U, V, W );
{
nvtx::ScopedRange r( "trace" );
m_scene->trace( camera_data );
}
// Draw the resulting image
Buffer buffer = m_scene->getOutputBuffer();
RTsize buffer_width_rts, buffer_height_rts;
buffer->getSize( buffer_width_rts, buffer_height_rts );
int buffer_width = static_cast<int>(buffer_width_rts);
int buffer_height = static_cast<int>(buffer_height_rts);
RTformat buffer_format = buffer.get()->getFormat();
GLvoid* imageData = buffer->map();
assert( imageData );
switch (buffer_format) {
/*... set gl_data_type and gl_format ...*/
}
RTsize elementSize = buffer->getElementSize();
int align = 1;
if ((elementSize % 8) == 0) align = 8;
else if ((elementSize % 4) == 0) align = 4;
else if ((elementSize % 2) == 0) align = 2;
glPixelStorei(GL_UNPACK_ALIGNMENT, align);
gldata = QGLWidget::convertToGLFormat(image_data);
NVTX_RangePushA("glDrawPixels");
glDrawPixels( static_cast<GLsizei>( buffer_width ), static_cast<GLsizei>( buffer_height ),gl_format, gl_data_type, imageData);
// glDraw
NVTX_RangePop();
buffer->unmap();
}

Answer 1

After hours of debugging, I found out that I forgot to set the Camera-parameters right, it had nothing to go to with the OpenGL stuff.
My U-coordinate, the horizontal axis of view plane was messed up, but the V,W and eye coordinates were right.
After I added these lines in initializeGL()
m_camera->setParameters(initial_camera_data.eye,
initial_camera_data.lookat,
initial_camera_data.up,
initial_camera_data.vfov,
initial_camera_data.vfov,
PinholeCamera::KeepVertical );
everything was right.