I'm developing applications to display very large lidar/sonar datasets (millions of points). QML/Qt seems an attractive platform, since in theory one can quickly define the UI with QML, and implement the "back-end" with high-performance C++. The QtDataVisualization package also seems very useful, especially the Surface3D and Surface3DSeries components for my application. But the provided examples either demonstrate a pure QML approach - which is impractical for my application, with millions of points - or a pure C++ ("widget") approach - which loses the benefit of quickly designing the UI with QML and is locked to a desktop computing platform.
Can someone point to a working example showing how to set QML Surface3DSeries data from C++? This seems theoretically possible from the documentation, but I have been unable to do it, and none of the provided examples demonstrate it. Is this even possible, or is Qml/Qt "broken" in this regard?
Thanks,
Tom
It is possible, but not officially supported and not documented.
Related
The QT dev kit comes with some good examples of how to code features via trivial apps, but nothing comes close to showing how to structure a complex program in QT. What, if anything, should be global, etc? Pitfalls in designing your classes that would turn out to need a lot of eventual refactoring?
I'm sure there are plenty of open source KDE apps that would serve nicely, so I guess my question is what't the minimal amount of source code I'd need to download and set up in order to work with, say, Dolphin as a sample app? If the answer is 'all of KDE', then I guess this isn't practical (unless downloading and building all of KDE from source is easy enough to make that practical).
Any suggestions? Personally, I'm looking to build a browser-like app, but much simpler. So for an example to follow, something that handles sockets and multiple tabbed viewports would be nice.
Thanks,
Rob
The main advice regarding Qt itself is I would give is to try to spend as much effort as possible in learning to use Qt's Model View Delegate functionality. It can be a lot of work to wrap your head around, but once you get there, you can do very powerful things with it. Another relatively tricky topic you will want to invest learning resources in is memory management and how Qt facilitates (and doesn't facilitate) it.
One of the most confusing things to me was though that when your model is very complex, you might not want to have your core model class be a Qt model at all. Instead, I nowadays see Qt models as something that primarily provide data to views. If your model is very complex, you might want to use your actual, more complex model as a data source for the Qt model class (an QAbstractItemModel derivative), which in turn attaches to the UI view.
Also, Qt documentation is your friend. Qt is a wide framework and contains LOTS of useful functionality. I love the data structures in their ease of use, for example: QHash, QList, etc.
Project scaffolding features for beginners, for different project types in Qt Creator might indeed be useful. For now, the Qt Examples actually are quite good ones, and contain lots of good practices. You just need to pick and choose what you need.
I have been developing our Qt desktop app family for five years now. Our directory structure is quite unorthodox - the main thing is that we have lib/ under which we have grouped different related functionality in subdirectories. The thinking goes, if something is in lib, it is general-purpose and atomic enough to be used in several of the actual desktop applications in our software family.
Your question seems more general level than Qt. It is difficult to tell if you are looking for a more general level computer science education. Globals in general should be avoided, sure. OTOH, we do have a constants.h and other immutable configuration data that is global-like, since it is needed in many places. This adds state though, so it can have unpredictable consequences if you don't do it carefully.
You could look for directory structures in places like this, though I don't really follow this advice myself. http://hiltmon.com/blog/2013/07/03/a-simple-c-plus-plus-project-structure/
Unless you are planning to contribute directly to KDE, I would advice against learning KDE way of doing things. Not necessarily because they are doing things badly, but because it is a world of its own - the best practice for KDE development might not be the best practice for a stand-alone Qt app. (Disclaimer: I, as a UI developer, don't actually like KDE, so I do not know the project very well - aside from the fact that it indeed seems a bit monolithic to the outsider.)
So I wonder if something like Qupzilla would fit the bill for you? (Found via qt-apps.)
HTH.
I have been tasked with making several flex-driven visualizations of immense excel spreadsheets. The client wants the finished product to be as self-contained as possible. The problem being that flex doesn't offer as much computing horsepower as is needed. Is there an easy (or not easy) way to accomplish this. I am just trolling for pointers. Thanks in advance!
If you dont mind doing it the hard way, I have two options for you:
Pixel Bender: a tool originally designed for creating complex and CPU-intensive graphic filters and offload those calculations to the hardware. But it can be used for number crunching too. Here's an article that covers that topic: Using Pixel Bender with Flash Builder 4 as a number crunching engine. The language may not be like anything you're used to. I had a hard time wrapping my head around it.
Alchemy: a tool that compiles C or C++ code so it can be executed in the Flash VM. I am not certain how much performance can be gained for simple number crunching, but if you know C, this might be a path to investigate.
The first thing that comes into my mind - building a webservice that will do the hard work. But this is not a self-contained product though.
Apart from that - take a look at the apparat - http://code.google.com/p/apparat, it allows various optimizations, access to the low level AVM2 code - http://code.google.com/p/apparat/wiki/AsmExpansion and more. I do not think that as3 and flex compiler is so bad for math. Try to write the sample math function and test it using different languages.
I am currently considering writing a small game. It is essentially a map where you can zoom out and in, and in certain places click on info boxes where, at some point, I hope to integrate minigames. Granted, game might be overstating it. Think of it as an interactive map. The theme is how mathematics can be applied in peoples every day life to raise awareness on the usefullness of mathematics.
The question is how I as fast as possible can make a reasonable prototype. If I recieve enough positive response on this I might try to code "the real thing" and use the prototype to obtain funding.
However, I am at a crossroad. I want something to work rather fast and have some C++ experience coding optimization problems, mainly in c-style. I am not convienced, though, that coding it in C++ is the fast way to obtain a prototype. Though I have some experience coding in C++, but have no experience in coding any sort of GUI.
As I see it there is a number of possibilites:
C++, possibly using some library, such as boost or ???.
Start out purely webbased, using e.g. HTML 5 and java.
Python
C#/.NET
Others, such as?
I have to admit I have little experience with anything besides C++ and the STL.
So my question to this wonderful forum is basically, is there a language that provides a significant advantage? Also, any additional insight or comments is more than welcome!
Python is a simpler language than C++, and for prototyping it will help you focus on the task at hand. You can use Pygame, a game library built on the excellent cross-platform SDL library. It provides 2D graphics, input, and audio mixing features. SDL is mainly a C library (and thus compatible with C++), and there are a number of very useful libraries that integrate with it:
SDL_image for loading images in various formats
SDL_ttf for rendering text using TrueType fonts
SDL_mixer for audio mixing
SDL_net for networking
SDL_gfx for graphics drawing primitives
So if you prototype in Python using Pygame, there is a reasonable chance you’ll be able to port what you make over to C++ with minimal hassle, if and when you choose to do so.
Possible options:
Go with what you know the best. Anything else will require a learning curve, which may be weeks to months long. If you're willing to take that road in order to make your prototype, then there are some really great tools available.
BlitzBasic is a good way to go, and is basically designed to be for games
I've done little games in Java using Slick2D - but you'll need good grounding in object-oriented coding to work effectively in Java. If you've got that from C++, then you can see a tech demo I built in Slick2D called Pedestrians. It's open source, and has demo videos here.
You might also ask your question on https://gamedev.stackexchange.com/ - a Q/A site dedicated to game programming
I have to port a project from Borland C++ Builder 5.0 under Windows XP to Qt 4.7.1 using g++ under Windows 7/mingw. The libraries and command-line utilities are done, and now I have to tackle the GUI applications, which use Borland VCL.
Can anybody recommend any tools or libraries to make this task easier?
Does anybody have any experience of this?
Edited to add: Well, I took the bull by the horns, and implemented the GUI from scratch. And I have to say, the commentators were right: I can't see any way of using the existing Borland GUI to ease the process.
There are several big differences between VCL and Qt that will make an automatic conversion process quite difficult.
Qt uses signals and slots and inheritance where VCL uses events.
VCL components use absolute coordinates and Qt uses layouts. Of course, you could use absolute coordinates also with Qt, but the GUIs would be quite awful then.
VCL's TListBox and TTreeView classes are quite different from Qt's View and Model classes (although you could use QListWidget and QTreeWidget instead).
I guess it is much faster to design totally new GUIs with Qt than to create even a mediocre VCL-to-Qt converter. And the code will be much easier to maintain. I suggest that you take one VCL form of medium complexity and recreate that with Qt. After that you can make an estimation of the total recreation work. Also you will have a better understanding about the feasibility of a conversion tool, which you most probably would need to make by yourself.
Someone has written a tool to convert dfm's to qt ui files:
http://sourceforge.net/projects/dfm2qt4ui/
Its has a few small bugs but it can save several hours of time porting form designs. In some cases redesigning specific forms is preferable - but in many cases, having labels and roughly equivalent controls positioned for you saves a lot of point-and-click action.
I agree with the current consensus that automatic conversion from VCL to QT is not a good idea because the concept behind both is very different, and you are much better off learning "the QT way" and using that from the start.
However there is one major step that nobody has yet mentioned: refactoring! Before starting, make sure you refactor the original forms to remove as much business logic as possible and leave only what is really GUI code. It depends on how good your architecture already is of course, but the VCL designer tends to encourage putting as much as possible in forms (even going as far as having invisible "data forms" with non-visual components!), so you often find a lot of stuff in the form that shouldn't be there.
hi guys
i am in trouble with add picking object in a JOGL project.
i know that this could be done with pick buffer.. but i can't find examples
anyone?
In general, as you are probably aware, JOGL code translates directly from any other OpenGL examples you might see on the web.
GL_SELECT based picking seems to be very much out of favour these days; deprecated in the spec and poorly implemented by drivers.
Alternatives you can use are:
Rendering each object with a unique color (and all lighting / fog etc disabled) so you can determine which object the mouse is over via glReadPixels. (Clearing buffers after the picking stage so that you can then render your normal graphics). This approach is explained by the top rated answer in OpenGL GL_SELECT or manual collision detection? for example.
Ray-casting into your geometry (see the selection FAQ link below). This also means that you don't have to have an active gl context in the thread you call the code from, fwiw.
I've used both of these methods in the same application, currently having good results with the latter, but since most of the objects in that application are spheres it is a lot cheaper than it might be with arbitrary models.
http://www.opengl.org/resources/faq/technical/selection.htm