[vtkusers] using VTK rendering in an existing OpenGL context

[Bryn Lloyd]

Hi

I am trying to use some rendering functionality from VTK, inside an existing code base using direct OpenGL calls (on WIN32).

I have figured out from various posts, that I need to set the correct WindowId, ParentId etc. of the vtkWin32OpenGLRenderWindow:

vtkWin32OpenGLRenderWindow* renWin = 0;

void setupVtkRenderWindow(HWND _hWnd, HDC _hDC, HGLRC _hRC)
{
	if(renWin == 0)
	{
		renWin = vtkMyWin32OpenGLRenderWindow::New();
	}
	renWin->SetWindowId(_hWnd);
	renWin->SetParentId(_hWnd);
	renWin->SetDeviceContext(_hDC);
	renWin->SetContextId(_hRC);
}

Somewhere else, I am calling some OpenGL commands, and then adding a vtkRenderer+vtkActor to the window.

My vtkActor displays in the OpenGL context, but "it overwrites" anything which is displayed by the OpenGL commands.

I have set the vtkRenderer::EraseOff() option, and it seems then no background color is written. For a short while, the existing OpenGL triangles pop up, together with the vtkActor triangles. Then the OpenGL objects vanish again.

Does anybody know what I might have missed, or a project, which has implemented what I am trying to do?

Thanks a lot
Bryn