[vtkusers] Rendering VTK inside a QGLWidget

[Paul Rossi]

Thank you so much, Clinton

Just by following your tips i managed to render a sphere inside a qglwidget by using the vtkGenericOpenGLRenderWindow

However, i have a question at this point:
I kind of do offscreen rendering, and before and after the rendering i always call:

		glBindFramebufferEXT(GL_FRAMEBUFFER_EXT,m_uFramebuffer);
		GLenum glError = glGetError();

		if (glError != GL_NO_ERROR)
			throw Exception("Error binding framebuffer (%s).",gluErrorString(glError));


and

		glBindFramebufferEXT(GL_FRAMEBUFFER_EXT,0);
		const GLenum glError = glGetError();

		if (glError != GL_NO_ERROR)
			throw Exception("Error releasing framebuffer (%s).",gluErrorString(glError));

to attach and detach the fbo.
my problem is that this code renders well:

			renWin->PushState();
			renWin->OpenGLInit();
			renWin->Render();
			renWin->PopState();

but after that, if i try to detach the framebuffer i get an error "Invalid operation" (even if it renders properly)
I will now try to dig a little into the vtkGenericOpenGLRenderWindow, but do you know what it could be and how it could be fixed?

I also have a last question: is it possible to skip using the RenderWindowInteractor, and somehow feed events to vtk from qt events?
Otherwise, how should i proceed to get interaction from a qglwidget into a vtk interactor?

thank you so much already
Paul


06 октября 2011, 03:18 от Clinton Stimpson <clinton at elemtech.com>:
> 
> On Wednesday, October 05, 2011 04:54:40 pm Paul Rossi wrote:
> > Hi all,
> >
> > I have a problem and i havent been able to fix it.
> > i want to use VTK from Qt, and i know that there is the
> > nice QVTK module for that.
> > My problem is that i  have to do my rendering from within a QGLWidget
> > (i am using a sort of framework where my views are qglwidgets, and i
> > cannot use any other viewer class)
> >
> > I know it is possible to render  vtk from within a QGraphicsView, but i
> > still cannot find if or how to render a  vtkrenderer from within a
> > qglwidget
> >
> > any suggestion?
> >
> 
> Try using the vtkGenericOpenGLRenderWindow in VTK 5.8.
> You can also see QVTKWidget2 as an example of using it, but depending on what
> you are doing, it may be simpler.  Or simply use QVTKWidget2 which is derived
> from QGLWidget, if that'll fit in your framework.
> 
> If you do it yourself, you should at least call in the construction, depending
> on how you are going to use it:
> renWin->SwapBuffersOff()
> 
> in the resize
> renWin->SetSize()
> 
> in the paintGL()
> renWin->PushState()
> renWin->OpenGLInit()
> renWin->Render()
> renWin->PopState()
> 
> If you are also mixing calls to QPainter, make sure to call
> QPainter::beginNativePainting()/endNativePainting().
> 
> There's more to do if you want to use vtkRenderWindowInteractor as well.
> 
> --
> Clinton Stimpson
> Elemental Technologies, Inc
> Computational Simulation Software, LLC
> www.csimsoft.com
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