[vtkusers] How to put Qt widgets on top of a VTK OpenGL scene

[Elvis Dowson]

Hi Clint,
                  Just guessing here, when I use QWidget, the painter  
associated with the QGraphicsView with use a normal paint engine (in  
my case, type 3 which corresponds to Mac OS Core Graphics).

However, the moment I switch to QGLWidget, the painter associated with  
the QGraphicsView will use an OpenGL paint engine (type 7). So, for  
the openGL drawing to occur in the QGLWidget, I will some how have to  
integrate it with VTK.

So, now going by what you have done before, the simplest way to  
integrate it as a first step would be to create a new paint engine and  
re-implement the QPaintEngine::drawPixmap() method, correct?

Then, after that, if you re-implement all the other QPaintEngine  
methods, such as drawEllipse, drawPoints, drawLines, etc, using VTK  
drawing commands, or setting it up so that it uses the following vtk  
classes
- vtkPainterDeviceAdapter (e.g. DrawElements() method which has types  
for lines, vertex, triange, etc)
- vtkOpenGLPainterDeviceAdapter

or something like that to somehow get Qt to use the VTK OpenGL  
commands to directly render into the QGLWidget's OpenGL rendering  
context?

Whew, this stuff is crazy and I feel like I'm groping in the dark.

Clint, atleast, now I see how you have implemented the QVTKWidget, and  
the reasons behind your previous prototypes.

Best regards,

Elvis Dowson



On Oct 21, 2008, at 2:37 PM, Elvis Dowson wrote:

>
> What could be going wrong or preventing me from using QGLWidget to  
> render the OpenGL images? Is it because the commands executed in the  
> drawBackground method wasn't OpenGL ? Does this mean that if  
> somehow, I got the QGLWidget to share the OpenGL context with the  
> vtkRenderWindow, VTK will automatically catch and render the VTK  
> images using a shared OpenGL context?
>