I have been looking for ways to render a 3d scene using Qt QML controls. I saw there is a framebuffer example which uses Canvas3D control to get OpenGL 3d scene rendered. However this example uses JavaScript for the rendering logic.
I was looking for a way to do the same but via a C++ class. Is there any way to do so? Or any example available?
Ideally, I would like to use 3rd party renderer to create a scene. Any ideas?
Related
I am unable to do 2D vtk renders in QT without having override errors: Vtk charts break in QT, "no override found for 'vtkContextDevice2D".
While trying to solve this I have been reading about the vtkContextView and vtkGenericOpenGLRenderWindow classes.
vtkGenericOpenGLRenderWindow:
vtkGenericOpenGLRenderWindow provides a skeleton for implementing a render window using one's own OpenGL context and drawable. To be effective, one must register an observer for WindowMakeCurrentEvent, WindowIsCurrentEvent and WindowFrameEvent.
vtkContextView:
This class is derived from vtkRenderViewBase and provides a view of a vtkContextScene, with a default interactor style, renderer etc. It is the simplest way to create a vtkRenderWindow and display a 2D scene inside of it.
I do not understand how the vtkContextView works with OpenGL and was wondering if someone could help explain their relation to one another, and how the context view works.
Also, is there any other way to do 2D vtk renders without the using the context view? I cannot find any exmaples of 2D vtk renders in QT, any advice on how to do 2D renders of vtk in QT will be greatly appreciated.
Current Attempt to render 2D vtk chart:
view->SetRenderWindow(this->qvtkWidgetRight->GetRenderWindow());
view->SetInteractor(this->qvtkWidgetRight->GetInteractor());
Additional Code in main file:
QSurfaceFormat::setDefaultFormat(QVTKOpenGLNativeWidget::defaultFormat());
Additional Info: Win64 on 64bit machine, vtk8.2.0, Qt5.13.0, compiled/built in MCVS2017(Release x64) with cmake3.15.0(3D vtk renders work fine)
Finally figured it out with the help of VTK forums. I simply did not have vtkRenderingContextOpenGL2 in my CMake file(updated code too, had it backwards).
I'm creating an application, which interacts with OpenGL via QOpenGL* classes. The graphics is shown through a QOpenGLWidget, which is placed in a UI-form.
Now, there is a library for CAD purposes (Open CASCADE), an OpenGL interface of which requires a handle to the render window. The question is: can I somehow say the library to render everything to the mentioned widget?
In other words, is there a way to interpret the widget as a native, probably, platform-specific (HWND here) window, so that the library renders its own stuff exactly there?
Thanks
QOpenGLWidget is not the same thing as QGLWidget.
The classical approach for embedding OCCT 3D viewer, which you can find in Qt IESample coming with OCCT, creates QWidget with unique window handle flag, takes this window handle and ask OCCT to take care about OpenGL context creation for this window. This is most straightforward, robust and portable way with one limitation - Qt will not be able drawing semitransparent widgets on top of this QWidget. This is not a limitation of OCCT, but rather limitation of Qt Widgets design.
QOpenGLWidget was intended to solve this limitation by allowing to mix custom OpenGL rendering and normal widgets. The integration of external OpenGL graphics engine, however, became more complicated and fragile. It is not very helpful stealing winId() from QOpenGLWidget, as rendering content is expected to be drawn not into window itself, but rather into OpenGL framebufer object (FBO), created by QOpenGLWidget - see QOpenGLWidget::defaultFramebufferObject() property.
External renderer is expected to render into this FBO for proper composition of Qt widgets. Luckily, OCCT is flexible enough to allow such integration. Unluckily, such integration requires some knowledge of OpenGL, as well as its usage by Qt and OCCT.
For that, you need to ask OCCT wrapping OpenGL context already created by Qt (for that V3d_View::SetWindow() provides an optional argument of type Aspect_RenderingContext, which corresponds to HGLRC on Windows and can be fetched using wglGetCurrentContext() within rendering thread) as well as FBO created by QOpenGLWidget (for that, OCCT provides OpenGl_FrameBuffer::InitWrapper() and OpenGl_Context::SetDefaultFrameBuffer() methods, as well as OpenGl_Caps::buffersNoSwap flag to leave window buffer swapping management to Qt).
OCCT doesn't come yet with a sample using QOpenGLWidget, but you can find also qt/AndroidQt sample implementing similar thing for embedding OCCT 3D Viewer into QtQuick application.
After some investigation, I found that method QOpenGLWidget::winId() returns the correct handle. It's been found out only now, because the rendered scene disappeared immediately, leaving a black picture instead. However, when the viewport is resized, the scene returns back (and disappears again, though). Looks like Open CASCADE has problems with Qt 5 OpenGL implementation, since QGLWidget didn't have such problems, as far as I know.
I need to create a GUI with a file menu and menu in which the user can input parameters. The parameters are then used for drawing rectangles in a canvas which is part of the application window. Is there a way to scale the OpenGL subwindow to just one part of the screen and the parameter input to the other? The application needs to be written in C++.
Is it possible to create a GUI with QT and draw the rectangles in the same window using OpenGL? If not, what is the common way to integrate a GUI with OpenGL? (or any other graphics library which I can use to draw rectangles from points as easy as possible)
EDIT: I am not sure If OpenGL is necessary or there is a way to paint the rectangles on the canvas like you can in Java with paintComponent().
I have never used QT before so I am not aware of its capabilites.
you can use opengl window singly or use this in the common mainwindow. previous example (in first answer) show how to use opengl window in qt singly and without communication with other components of Qt (like menu, toolbar and ...). but you can add a opengl window to a mainwindow (like other widget) and use it alongside other widgets . this example can help you.
Yes, using OpenGL together with Qt is absolutely possible. There is even an example for that and Qt provides classes for a more object oriented way of using OpenGL. Have a look here (Section "OpenGL and OpenGL ES Integration") for more details.
I wonder if it's possible to use Awesomium to render the GUI over the DirectX 11 game (I do NOT use .NET, it's C++/DirectX 11 game)?
It would involve:
Rendering the scene on the window with DirectX 11 (just as I am doing it now).
Rendering the GUI with Awesomium from HTML/CSS over the previously rendered scene.
Note that some GUI elements should be semi-transparent or rounded - so it's not only rendering on some rect, but also blending.
Is it possible? Or maybe I could make it another way (e.g. telling Awesomium to use DirectX for rendering somehow)?
Or maybe I could draw an semi-transparent DirectX texture in Awesomium, and then render it over the scene with DirectX? I know that rendering to texture resource is possible with Awesomium, but does it supports transparency & semi-transparency?
If not, are the good alternatives for what I wanted to achive with Awesomium?
Yes. It can be done.
If you look at the documentation of the Awesomium WebView class it has a surface() method which will return the views backing bitmap.
Here is some c++ documentation for the class.
http://awesomium.com/docs/1_7_0/cpp_api/class_awesomium_1_1_web_view.html
You can copy this bitmap to a texture in DirectX and render it as layer on top of your game creating your UI.
You also have to route and translate input into Awesomium. You can style your UI however you like using HTML, CSS and Javascript. You can make it rounded in this way and introduce transparency.
I won't repeat a perfectly good tutorial on doing this. You can find one here.
http://www.gamedev.net/blog/32/entry-2260646-sweet-snippets-rendering-web-pages-to-texture-using-awesomium-and-direct3d/
How you render your texture after it is written doesn't have anything to do with Awesomium. Choose your blend modes and/or use shaders with output texture for desired effect.
I am making a 3D game with OpenGL ES 2.0 and want to use QML as an overlay for the user interfaces.
I know that I can embed my OpenGL code inside a QGLWidget but how can I force QML to redraw the view as often as possible?
Additionally will I get performance issues because I am embedding the OpenGL view?
If you want to render your game with OpenGL and use QML for the UI, consider using the Qt Quick Scene Graph:
Mixing Scene Graph and OpenGL
Scene Graph - OpenGL Under QML