[SOLVED] Using a vtk renderer in QtQuick

[Martell Malone]

I've made more progress on getting it working on GLES systems.
My window flickers for a frame and then goes gray.

Also for that frame the scene is upside down and a texture is missing.

The last two things that I wish to ask

1. I noticed
   setFbo isn't called anywhere?

and also I have two size methods setRect and setSize

@void ColorNode::setSize(const QSize size)
{
if (size == m_size) return;

m_size = size;
//m_fbo = NULL;
//m_texture = NULL;

QSGGeometry::updateTexturedRectGeometry(&m_geometry,
                                            QRectF(0, 0, m_size.width(), m_size.height()),
                                            QRectF(0, 0, 1, 1));

markDirty(DirtyGeometry);

}

void ColorNode::setRect(const QRectF rect)
{
if (m_rect == rect) return

    markDirty(DirtyGeometry);
    m_rect = rect;

}@

I'm guessing yous implementation is different?
Could I get a quick look :)

I think I'm really close

[z.emb]

Actually, I posted almost the whole implementation already, but here you go: "Node":http://pastebin.com/8CgheNzm . The implementation of the texture and the item are already posted.

bq. I noticed setFbo isn’t called anywhere?

You may have noticed that I pass the FBO to the constructor of the texture ;-)

bq. What header did you include?

I compiled Qt 5.0.0 with ANGLE deactivated and the -opengl desktop flag, because I use VTK which also uses the native OpenGL system.

[Martell Malone]

I need to set the geometry in my setsize or I get nothing in the window.

@
QSGFboTexture::QSGFboTexture(QGLFramebufferObject* fbo)
:QSGTexture()
{
m_fbo = fbo;

// setFbo(fbo);
if (m_fbo != NULL)
firstTimeBound = true;

}
@

same as setFbo ;-)

The problem is that on ANGLE we are using a GLES emulator not OpenGL.
Those two functions don't exsist.

What happens to your window when you dont call the push and pop?

@void ColorNode::preprocess()
{
if(m_fbo == NULL) return; //will happen a few times

QOpenGLContext::currentContext()->functions()->glUseProgram(0);
m_fbo->bind();

CCDirector::sharedDirector()->mainLoop();

m_fbo->release();

m_fbo->toImage().save("name.png","png");

}@

[z.emb]

Its not working without the push and pop (nothing is rendered, only the background). Unfortunatelly I cannot tell you why, I'm no OpenGL expert.

[Martell Malone]

I think I understand why.
The only problem is GLES doest support those functions so how do we get around them?

Maybe I should make a new thread to this issue?

[Martell Malone]

I found a new way of solving this problem.

It Involves setting up a separate opengl context and switching between the two before and after binding and releasing the fbo.

Any idea how to draw correctly for a y inverted fbo.
On qquickpainteditem we can set it to flip but not for the qsgtexture :/

[z.emb]

Hey, thanks for your reply. Can you provide some code how you do that?
In my case, it also seems to be the cleanest way to do the same thing and I wan't to try that. :-)

For the flipping problem I would naivly just scale (glScale) the y-Axis with -1. But as I mentioned, I'm no OpenGL expert.

[Martell Malone]

Hey z.emb

I used what was on this thread.

http://qt-project.org/forums/viewthread/25268/

I just changed this line for the flip y.

QSGGeometry::updateTexturedRectGeometry(&m_geometry,
QRectF(0, 0, m_size.width(), m_size.height()),
QRectF(0, 0, 1, 1));

to

QSGGeometry::updateTexturedRectGeometry(&m_geometry,
QRectF(0, 0, m_size.width(), m_size.height()),
QRectF(0, 1, 1, -1));//0011 = old y fliped

[z.emb]

Can you give me some code how you switched the GL-context?

[Martell Malone]

Hey Guys,

Apologies about not replying.
I didn't realize I got a response.

I swapped the context at the very beginning by using the code in this thread

http://qt-project.org/forums/viewthread/25268/

Hope that helps Ricky, just got your pm.

Many Thanks
Martell

[rlonka]

Hi,

I still did not get it.
Could you, please, anyone post a full example about rendering vtk to qtquick?
I was trying to understand the discussion but I did not get through...

Best regards,

radek

[rpetryniak]

Hey, I join to this request. Even the simplest example would be helpful.

Regards,
rafal

[niker91]

I have created a repository with code that integrates VTK with Qt QuickControls 2, tested with VTK 8 and Qt 5.9. You can find the code here https://github.com/nicanor-romero/QtVtk with building instructions in the README. Also a brief article about it,
https://blog.bq.com/es/integrating-qtquickcontrols-2-with-vtk/