I have a project that involves OpenCV among some other media related functionality and after playing with OpenFrameworks it seems to be perfect for the task, well nearly perfect ;)
This project is actually a Flash project and I have a working connection to C++ for all the image processing for speed. The problem is that OpenFrameworks require the following code to init before the ofRunApp:
ofAppGlutWindow window;
ofSetupOpenGL(&window, 1024,768, OF_WINDOW); // <-------- setup the GL context
Is there an easy way to use the OpenCV related functionality in OpenFrameworks without opening any window? Just for the record I would prefer to use OpenFrameworks rather than vanilla OpenCV for the flexibility of OF and it's other features.
Thanks in advance,
a.
There is no 'official' way to do this with openFrameworks.
Since openFrameworks has swappable renderers, you could write one to do this. But this seems to be a lot of work because many openFrameworks internal rely on a window and GL context.
You can find he most promising attempts to solve this problem here and here. Maybe you can search the openFrameworks on your own to find probably more. Even better: feel free to start a new topic to get people see that there is a need for headless rendering.
Related
My situation
I want to build a cross platform application, with a gui, that displays a 3d view of some simple cubes, that the user can interact with. Qt seemed like a good tool for the job and I think I have the gui part sufficiently down for the most part. For the 3d part OpenGl or the qt/3d implementation seemed like the right tool, but it does not work. When I try to run the examples from Qt, that use a 3d view, they are unstable, they crash, show a black window and on the offchance, that I find one, that does work there is aggressive flickering and my entire system becomes unresponsive when I only try to resize it. I don't know what is wrong, I don't think I can do a better job, than the official examples and I don't think, that trying to debug the examples is the way to go. (If someone has an idea how to fix this tell me, but I don't even have an error message)
My question:
Is there a simple framework, that would allow me to display simple 3d shapes and include that in a Qt application. I don't need shadows, or reflections or transparency or anything more fancy, than ambient light. Just some solid coloured boxes I can rotate and click on. I think it would even be fine, if it ran on CPU rather than GPU. It would be nice, if I could keep using C++, but if it only exists in another language, what gives. I don't really want to build a framework from scratch. How could I include such a foreign framework in Qt?
I am using ubuntu 20.04 with intel graphics, but as I said, I want the resulting application to work on as many platforms as possible.
I am working on an application that uses Qt3D with then OpenGL renderer. Deploying the app to a handful of users, I found some severe issues with Intel Integrated Graphics, ranging from crash to rendering bugs like flickering. This unfortunately doesn't comes from Qt or OpenGL itself but more from how Intel implements their OpenGL drivers.
The crash bug seems to impact older intel chips, very few references of that apart some random minecraft FAQ on reddit: https://www.reddit.com/r/Minecraft/comments/48ktct/19_faqs/
But what is claimed there seem to align with what my users are experiencing.
The flickering bug has only been reported recently and I unfortunately don't have the right hardware to replicate it yet...
I know it's like random, not sourced information but I thought that personnal experience might help.
I used osgQt many years ago. It looks active still. I know the military likes them.
https://github.com/openscenegraph/osgQt
Anyone who has experimented with Qt QML and 3D OpenGL, I am interested in 2 frameworks I've read about, but it is not clear to me if in fact they are the same framework. The most interesting of the two is outlined in this Qt Developer Days 2013 video presentation by Krzysztof Krzewniak:
http://www.youtube.com/watch?v=29wCpA0DBZI
While very interesting, unfortunately I cannot find anywhere else online some source code for this, or even the name of the framework discussed.
There is QtQuick3d:
http://doc.qt.digia.com/qt-quick3d-snapshot/
However, I cannot tell if in fact this is describing the same framework from Dev Days or if they are separate (and apparently somewhat similar) frameworks? My initial look at the API in comparison to the video suggests they are different, which seems rather redundant to have 2 significant projects in the Qt community attempting to do the same thing.
Can anyone with some knowledge in this area of QML provide some pointers here?
Right, so let us start with some history behind...
Qt was initially a 2D framework for rendering computer graphics UI for simple desktop applications.
Qt3D was developed earlier than qml became mature as an extension to the 2D world provided by the QtGui module, or even QtOpenGL.
It was a 3D Qt api for rendering 3D content on the screen. It had different aspects to deal with 3D objects, build them, put them on the screen, compute intersection, and so on.
The idea was to bring easy to create application concept into Qt rather than always going through QtOpenGL or lower-level API for creating games, simulators, cad applications, and so on.
Right, when QML came out and kept maturing, the Qt3D contributors in Brisbane thought that it would be nice to put a QML API on top of the existing Qt3D C++ API for easy use in QML application. That is how we come to QtQuick3D.
When Nokia decided to shut the Brisbane office done, the Qt3D module pretty much became unmaintained and abandoned only getting a few bugfixes from the community every now and then.
There is some work in progress by KDAB to re-architecture and re-design the module, but it is not mature yet, and it can be found in a separate branch.
The video you are referring to is not dealing with the unmaintained Qt3D module. Rather, it tries to build 3D based on the new scene graph introduced in Qt. Since, there is no Qt3D module working nicely with the new SG in Qt 5, people become pragmatic and move on. That is what you see in the video.
Now, as you can see this is not quite a duplication, but... In the future, the new Qt3D architecture might be acting better with the new scene graph. In fact, KDAB has put a lot of effort into bringing the OpenGL support into QtGui up to real world.
That was the foundation for the Qt3D module which will probably be used in the future (hopefully) by 3D applications written based on Qt, but in the meantime... the video shows how to build hardware accelerated 3D UI based on what we have today.
These two 3d libraries are not the same, you are correct.
There is plenty of reference information you've already linked to online regarding Qt3d 1.0 and QtQuick 3d which are similar and related.
The OpenGL work in the video presentation is something much newer. It is directly laid on top of the QSceneGraph and QQuickWindow functionality.
My recommendation is to not use the approach in this video or the Qt3d/QtQuick3d library. Instead, wait for the KDAB to finish Qt3d 2.0 (which may already be out, you should check). Qt3d 2.0 is a full library for QML that will let you do what is demonstrated in this video.
(http://qt-project.org/wiki/Qt3D-wip-newapi-Overview, http://prezi.com/u-ewejoqxqj2/qt3d-20/)
There are quite a lot of outdated info floating around wikis, and finding useful info and a non-obsolete repository was a pain. So here's what I learned a few months back:
The correct and, as far as I know, the only currently valid git repo is this:
git://gitorious.org/qt/qt3d.git
The "There is some work in progress by KDAB...not mature yet...found in a separate branch." paragraph of Laszlo Papp's answer seems to refer to wip/newapi branch, while master branch seems to be maintained in compilable state (meaning, I have been able to compile it the few times I've tried, YMMV). Master branch should be fine for playing around with Qt3D, but looks like API is going to change.
I played with it a few months ago on Windows 8.0, the MinGW toolchain that is installed with SDK, and using native full OpenGL drivers (which I had to fetch from ATI web site for my card, default Windows drivers are not enough). And looks like it has not broken to bit rot, an example still built and I have a moon rotating on this screen.
It has README file, which will tell you how to build it, starting with building Qt5. Here another good link for that, since the qt3d README is not very comprehensive. And if you're on Windows, just skip Webkit and its deps, unless you really need it, because those extra deps can be a bit of hassle.
Glut seems rather old, and SDL also as if it's not the youngest anymore - what is being used as (cross-platform) window manager for OpenGL nowadays?
Cross platform UI toolkit
1. wxwidgets
2. fltk
3. qt
4. glut(freeglut)
5. sdl
I have used glui. Sucks real bad(in terms of performance). There huge difference in performance penalty just by including glui(without actually using it) in your apps.
To be honest, i prefer platform specific UI toolkit. Faster. Reliable.
Depends on how you want to use it. Don't think there is a clear winner.
I like to use Qt because I'm familiar with it so it feels easy to me, and because I use it for other UI elements in my mostly windowed openGL apps.
Haven't tried it myself, yet, but want to in my next project. It seems to be very popular.
SFML . It`s the "successor" to SDL written in C++
I am using freeglut, but it is just a bit improved glut.
You can also use QT
I think GLFW is the best choice for small to medium applications/games. This type of libraries should be easy,small and fast with no extra services such as image helper functions and so on. GLFW is going to remove all helper functions to focus on the main goal.
QT is the best for graphics applications but not for games or small applications.
I have a simulation software (C++) that runs on the command line. It is platform independent (currently compiling and running on Windows, MacOS X and Linux). When the simulation ends, I visualize the result with SDL; it is a very basic 2d view, mainly color squares next to each other.
I would like to have a user interface on top of the simulation so that I can start and pause the simulation, and change the parameters on the fly. Something pretty simple I guess. Well, ideally I will also add a grapher somewhere to see the evolution over time of some parameters.
Now, I am wondering what direction I should go.
Should I try to use one of the UI libraries for SDL ?
Or maybe wxwidget in conjunction with SDL ?
Or simply wxwidget and get rid of SDL ?
Do you have any experience with this ?
Thanks in advance
Barth
PS: I tried to use AGAR, a SDL UI library. It seemed very promising but I couldn't get it working. Not even the helloworld.
It may be worth you time to look into Qt. It is generally the most mature free Gui framework available. It is cross platform. And it has hardware accelerated rendering if your drawing needs some speed.
Here is a comparison posted on WxWidgets site.
In the end if your windowing needs are minimal you should choose the framework you are most comfortable with.
Probably using wxWidgets without SDL would be the easiest way to go. SDL is a media layer -- it's supposed to allow cross-platform media application development. As you only need graphical display, you only need wxWidgets -- and it will be a lot easier too!
You would benefit from SDL if:
you'd need very fast blitting of very large amount of surfaces (we're talking the 60fps range here)
you'd use RLE, color keying or other graphics operations
you'd use other media (sound, advanced real-time input, etc)
you'd need to run the software on embedded systems (handheld consoles, etc)
If the answer to all 4 is "no", then you won't benefit from SDL, and using wx alone will be much easier.
So, I'm going to develop a Pac-Man clone with Qt. The problem is that I do not really know where to start.
I quickly take a look at the documentation and some demo. I also downloaded some game sources on qt-apps.org. And it seems that there is a lot of ways to develop a game with Qt!
In your experience, which part of Qt should I consider to develop a Pac-Mac clone ?
The Animation Framework
The Graphics View Framework
The Paint System
Qt Declarative
Any help would be appreciated.
I think that QGraphicsView framework is the best way. Create a QGraphicsScene, some QGraphicsItems for the elements of the game. You have collision detection for free.
Most of KDE games are based on the QGraphicsView framework. It is a good fit for simple game development.
I'm currently working on a project providing gaming-specific Qt Quick Components for cross-platform game development, might be of interest: http://v-play.net :)
At the very minimum you will want to look at QGLWidget. You can get an OpenGL program up in a few minutes by deriving from QGLWidget, it will create the window, context, handle mouse and keyboard input, etc. Create a QTimer to trigger updateGL() every 10-15 ms or so and your good to go. I think there is a demo somewhere for setting this up, but it has been awhile since I saw it.
If you want to embed widgets into the window, I would look at QGraphicsView. There is a demo of this called boxes. Just beware the demo is a tad hard to learn from as several classes are thrown into the same file and it might take a few moments of tracing to figure out where the flow is.
Since you are doing a 2d game, you might want to look at using QPainter on top of OpenGL. This allows you to draw primitives easily instead of doing them with OpenGL calls. I never could get this to stop flickering in fullscreen though.
There's a book about game development in Qt here, it's a bit old, but it might give you some ideas. But IMHO, Qt is widget based and is a bit slow for a game, you might consider using SDL or OpenGL.
I'm developing a simulation of rigid bodies with Qt and OpenGL using the PhysX API from Nvidia. If you want to see this approach, look at my project at github: http://github.com/lucassimao/Simulacao-Estereologica
Well, one place to look could be the Gluon game development framework, which is currently under development. It depends on what you're really aiming for with your PacMan clone, but Gluon may well be what you're after: https://github.com/KDE/gluon
If anyone else is interested in learning how to make GAMES using C++ and Qt, have a look at my YouTube tutorial series. It explains the graphics view framework through a series of videos which build upon a single game that we start in tutorial 1.
C++ Qt Game Tutorial 8 - Adding Graphics
If you are not comfortable with Qt yet, then I REALLY loved VoidRealm's Qt tutorial series, also on youtube (C++ Qt 1 - Introduction to QT programming).
A good start would be:
Qt Examples And Tutorials
Perhaps if you need to cheat you may want to look here
xpacman.tar.gz