What's this about?
We have a C++ application dealing with image processing and computer vision on videos using OpenCV, we're going to rewrite it from scratch and need some help deciding what technologies to use. More specifically, I need help on how to choose the technology I'd use.
About the app
The app's functionality is divided in modules that are called in an order defined by a configuration XML file and can also be changed in runtime, but not in realtime (i.e. the application doesn't need to close, but the processing will start from scratch). These modules share data in a central datapool.
Why are we starting from scratch?
This application wasn't planned to be as dynamic as it currently strives to be, so it's grown to be a collection of buggy patches, macros and workarounds; it's now full of memory leaks, unnecessary QT dependencies, slow conversions between QT and OpenCV image formats and compilation and testing times have grown too much.
Language choice
The original code used C++, just because the guy who originally started the project only knew C++. This may be a good choice, because we need it to be as fast as possible, but there may be better choices to account for the dynamic nature of the application.
We're limited by the languages supported by OpenCV (C++, Java and Python mainly; although I've read there is also support for Ruby, Ch, C# and any JVM language)
What is needed
Speed: We're aiming for realtime tracking. This may rule out Python and Ruby.
Class Instantiation by name: Although our C++ macros and class registration system work, a language designed to be dynamic that has it's own runtime would be nice. Maybe Objective-C++, or Java.
What would be ideal
Module/Plugin/Extension/Component Framework: Why reinvent the wheel, using a good framework for this would let us focus on what's special about our app. There are many options here. Objective-C has it's NSBundles; C++ has libraries like Boost.Extension, Pluma, DynObj, FxEngine, etc; C has C-Pluff; I'd even say there are too many options.
Runtime class loading and reloading: From a developing point of view, it would be interesting to be able to compile and reload just one module. I've seen this done in via code injection in Objective-C and using Java's reflection.
What am I missing?
I have too many interesting options!
Here's where I need help, based on your experiences in modular app development, with this constraints, what kind of language/framework feature should I be looking for?
What question should I make myself about this project that would let me narrow my search?
Edit
I hadn't noticed that OpenCV had GPU bindings only for C++, so I'm stuck with it.
Now that the language is fixed, the search has narrowed a lot. I could use Objective-C++ to get the dynamism needed (Obj-C runtime + NSBundle from Cocoa/GnuStep/Cocotron), which sounds complicated; or C++ with a framework.
So I'll now narrow my question to:
Is using NSBundle in a crossplatform way with Objective-C++ easier than it sounds?
What C++ framework will provide me with hot-swappable modules?
The main reason for swapping modules in runtime is to be able to change code in a fast way, would Runtime-Compiled C++ be a better solution?
Meta: I did my research on how to ask a question like this, I hope it's acceptable.
"What question should I make myself about this project that would let me narrow my search?"
if you need gpu support(cuda/ocl), your only choice is c++.
you can safely discard C, as it won't be supported in the near future
have no fear of python, even if you need direct pixel access, that's all numpy arrays (running c-code again)
i'd be a bit sceptical of ruby, c# ch and the like, since those bindings are community based, and might not be up to date / maintained properly, while the java & python bindings are machine - generated from the c++ api, and are part of the official distribution.
If you're looking for portability and have large memory for disposal then you can go with Java.
The performance hit between C++ and Java is not that bad. For conversion between Mat and other image format I'm still not sure, coz it needs deep copy to perform that, so if your code can display the image in openCV native format then you can fasten the application
pro :
You can stop worrying about memory leak
The project is much more portable compared to C/C++(this can be wrong if you can avoid using primitive datatypes which size is non consistent and for example always use int*_t in C)
cons:
slower than C/C++
more memory and CPU clock needed
http://www.ibm.com/developerworks/java/library/j-jtp09275/index.html
I have a fair hang of programming in various languages. I have been implementing my codes for research using MATLAB (during the past few months) and for the first time really noticed the difference in execution speed of MATLAB v$ C. (As much as I love the blazingly fast prototyping capabilities).
I am looking to pickup C++ and start using it in my research. I am aware of OOP and have programmed fair bit of Java (relatively long back) and C++ (even longer back). I would like to really get deep into C++ now and hence need suggestions for resources on the same:
What C++ things I need to pick up (STLs and. ) to really make good use of C++?
What is a good tutorial/manual to get started with?
What are the numerical/scientific libraries for C++? GSL? Is there a equivalent (features) of Scipy/Numpy for C++?
I shall be programming on Linux, so I shall be using g++ .
Any pointers to previous SO questions also appreciated.
You'll want to get to grips with parallel programming as quickly as possible. For message-passing I like this book by Karniadakis and Kirby. Of the books on OpenMP, for distributed-memory programming, this one is the best.
If you can get access to them, then Intel's Threading Building Blocks, Maths Kernel Library, and Integrated Performance Primitives are good to have. If not, there are plenty of open source alternatives, start looking at Netlib.
Oh, I almost forgot BOOST, which is a must.
In regards to numerical stuff like Numpy, you should have a look at both:
Blitz++ http://www.oonumerics.org/blitz/
and
Jama/TNT http://math.nist.gov/tnt/download.html
On the library side, check out Armadillo. It almost gives you the full extent of MATLAB's array manipulation syntax and uses LAPACK and BLAS (ATLAS) under the hood.
This tutorial absolutely rocks, but you may not want to tackle it initially.
http://www.parashift.com/c++-faq/
Make sure to read up on the STL (standard template library) and other stuff, using sites like:
http://cplusplus.com/
And, check out the Boost library:
http://www.boost.org/
To make really good use of C++, you need to learn at least the STL, that alone will save you lots of time, but as parashift mentions, C++ OOP is only programming with objects, if you don't use dynamic bindings.
TRNG is a parallel random number generation library. It allows you to create multiple independent streams and was designed for use on clusters.
I just heard from somewhere that for numerical computation, "MATLAB does offer some user-friendly APIs. If you call these APIs in your C/C++ code, you can speed up computation dramatically."
But I did not find such information in MATLAB documents like http://www.mathworks.com/support/tech-notes/1600/1622.html and http://www.mathworks.com/access/helpdesk/help/techdoc/matlab_external/bp_kqh7.html. All I learned from these websites is that MATLAB can be called in C and C++ by Matlab engine or by compiling M-files into libraries by mcc. They don't mention any built-in numerical MATLAB APIs that can be called in C/C++.
Can someone please clarify?
Thanks and regards!
You want the "Engine" routines. This allows you to start up a background MATLAB process from C and execute calculations on it: relevant MATLAB documentation.
It works pretty well, have a look at the examples. I would say the most annoying thing getting it working is marshaling the data between C and MATLAB. But that's always a problem when doing this kind of thing.
It sounds like you're looking for the code generation tools in the embedded matlab toolbox or real time workshop.
Do doc eml and look for a the LMS (least mean square) equalizer demo.
The code generator is quite good, it will give you a make file that will build a static library. It's easy to use with your stand alone C/C++ code.
There could be a few things that quote is referencing, I assume that it is referring to the MATLAB Compiler. So going from MATLAB -> C++ you can use the compiler to build standalone "faster" applications. However, when speed testing the improvement, I've noticed it to be negligible. Honestly, you're probably far better off coding your work in C from the get-go, the code that the compiler generates is spaghetti and non-object oriented. I should also mention that this is an expensive extension to Matlab.
You can use the MCR in your own c++ project as a stand-alone library (details)... but you might get similar results using Numerical Recipes.
Disclaimer: I used this product 2-3 years ago, things could be different now.
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Closed 10 years ago.
C++ just sucks too much of my time by making me micro-manage my own memory, making me type far too much (hello std::vector<Thingy>::const_iterator it = lotsOfThingys.begin()), and boring me with long compile times. What's the single best alternative for serious real-time graphics programming? Garbage collection is a must (as is the ability to avoid its use when necessary), and speed must be competitive with C++. A reasonable story for accessing C libs is also a must.
(Full disclosure: I have my own answer to this, but I'm interested to see what others have found to be good alternatives to C++ for real-time graphics work.)
Edit: Thanks everyone for the thoughtful replies. Given that there's really no "right" answer to this question I won't be selecting any particular answer. Besides I'd just pick the language I happen to like as a C++ alternative, which wouldn't really be fair.
What about D Programming Language?
Some links requested in the comment:
Win32 Api
Derelict (Multimedia lib)
I wouldn't discard C++. In fact, I would consider adding Boost to your C++ library, which makes the language much more usable. Your example would become:
BOOST_FOREACH( Thingy& t, lostOfThingys ) {
// do something with 't'
}
Boost has tons of tools that help make C++ a better language.
C# is a nice language that fits your requirements, and it is definitely suited for graphics, thanks to the efforts of Microsoft to provide it with great tools and libraries like Visual Studio and XNA.
Real-time + garbage collection don't match very well I'm afraid.
It's a bit hard to make any real-time response guarantees if a garbage collector can kick in at any time and spend an undefined amount of processing...
I disagree with your premise. When used carefully and properly, C++ is a great language, especially for a domain like real-time graphics, where speed is of the essence.
Memory management becomes easy if you design your system well, and use stl containers and smart pointers.
std::vector::const_iterator it = lotsOfThingys.begin()) will become much shorter if you use
using namespace std;
typedef vector::const_iterator ThingyConstIter;
And you can shorten compile times significantly by breaking up your systems into reasonably self-contained modules, by using precompiled headers, or by using the PIMPL idiom.
Perhaps a hybrid approach. Python and C++ make a good combination (see, for example, PyGame).
Some variation of Lisp that compiles to machine code could be almost as fast as C++ for this kind of programming. The Naughty Dog team created a version of Lisp called Game Oriented Assembly Lisp, which they used to create several AAA titles, including the Jak and Daxter series. The two major impediments to a Lisp approach in the game industry would be the entrenched nature of C/C++ development (both tools and human assets are heavily invested in C/C++), as well as the difficulty of finding talented engineers who are stars in both the game programming domain and the Lisp language.
Many programming teams in the industry are shifting to a hybrid approach wherein the real-time code, especially graphics and physics code, is written in C or C++, but game logic is done in a higher-level scripting language, which is accessible to and editable by programmers and non-programmers alike. Lua and Python are both popular for higher-level scripting.
Let's not forget to mention the new 'auto' use:
auto it = lotsOfThingys.begin(); // Let the compiler figure it out.
auto it2 = lotsOfFoos.begin();
if (it==it2) // It's still strongly typed; a Thingy iter is not a Foo iter.
As a developer/researcher/professor of 3D VR applications for some 20 years I would suggest there is no alternative (except possibly C). The only way to reduce latency and enable real-time interaction is an optimized compiled language (eg C or C++) with access to a fast relaible 3D graphics library such as OpenGL. While I agree it is flustrating to have to code everything, this is also essential for performanc and optimization.
Sometimes, looking outside the beaten path you can find a real gem. You might want to consider PureBasic (Don't let the name mislead you). Here's some details:
PureBasic Features
Machine Code (Assembly) executables (FASM)
In-line Assembly support
No run-times needed (no DLLs needed,etc.) 1 executable file
Tiny executables (as small or smaller/as fast or faster than C++ w/out the runtime)
You can write DLLs
Multi-thread support
Full OS API support
Multi-platform support
Windows 95-2003
Linux
Mac-OS X
Amiga
2D & 3D game development
DirectX
OGRE
Generous Licensing
Inexpensive (79 Euros or about $112)
Life-time license (all future updates & versions included)
One price for all platforms
External Library support
3rd party DLLs
User Libraries
On-line Support
Responsive development team led by it's creator
On-line forum
One place for answers (don’t have to go all over the net)
Huge amount of sample code (try code out while in IE with IEtool)
Fast replies to questions
Bonus learning (alternative to learning C++)
API
Structures
Interfaces
Pointers
Visit the online forum to get a better idea of PureBasic (http://www.purebasic.fr/english/index.php) or the main site: www.purebasic.com
I completely agree with the mention of C# for graphics programming. It has the slight disadvantage of being a managed language and allowing the garbage collector free reign over your application is framerate suicide after a while but with some relatively intelligent pool allocations made early in the program's life any real issues can be avoided.
Several people have already mentioned XNA, which is incredibly friendly and well-documented and I would like to echo that recommendation as well. I'm personally using it for my hobby game projects and it has treated me very well.
XNA isn't the only alternative, though. There is also SlimDX which is under constant development as a means of providing a lean wrapper of DirectX in a similar fashion as Managed DirectX (which was, I believe, discontinued by Microsoft in favor of XNA). Both are worthy of research: http://code.google.com/p/slimdx/
There are no true alternatives for big AAA titles, especially on the consoles. For smaller titles C# should do.
C# is a good answer here - it has a fair garbage collection (although you'd have to profile it quite a bit - to change the way you handle things now that the entire memory handling is out of your hands), it is simple to use, have a lot of examples and is well documented.
In the 3D department it gives full support for shaders and effects and so - that would be my choice.
Still, C# is not as efficient as C++ and is slower due to overhead, so if it is speed and the flexibility to use any trick in the book you like (with pointers and assembly if you like to get your hands dirty) - stick to C++ and the price would be writing way more code as you mentioned, but having full control over everything including memory management.
I would say the D programming language is a good option. You can link to C object files and interface with C++ code through C libraries. D has garbage collection, inline assembly, and game developers have created bindings to SDL and OpenGL libraries, and are also actively working on new game development apis. I love D. Too bad my job doesn't demand it's use. :(
Like James (hopkin), for me, the hybrid approach is the best solution. Python and C++ is a good choice, but other style like C#/C++ works. All depends of your graphical context. For game, XNA is a good platform (limited to win32), in this case C#/C++ is the best solution. For scientific visualization, Python/C++ is accepted (like vtk's bindings in python). For mobile game JAVA/C++ can works...
If you are targeting Windows, C++/CLI (Microsoft's .NET 'managed' dialect of C++) is an interesting possibility, particularly if you want to leverage your C++ experience. You can mix native code (e.g. calls to C-style libraries) with .NET managed code quite seamlessly, and take advantage of .NET GC and libraries.
As far as concerns about GC impacting 'real time' performance, I think those tend to be overblown. The multi-generational .NET GC is very good at never taking much time to do a collection, unless you are in some kind of critical low-memory situation. I write .NET code that interacts with electronic derivatives exchanges, where time delays == lots of $$$, and we have never had a GC-related issue. A few milliseconds is a long, long time for the GC, but not for a human interacting with a piece of software, even a 'real time' game. If you really need true "real time" performance (for medical devices, process control, etc.) then you can't use Windows anyway - it's just not a real-time OS.
Lot of game engines can fit your need, I suppose. For example, using SDL or Cairo, if portability is needed. Lot of scripting languages (coming in general with easy syntax and garbage collection) have binding to these canvas.
Flash might be another alternative.
I will just point out Processing, which is an open source programming language and environment for people who want to program images, animation, and interactions.
Actually, it is a thin wrapper around Java, making it look like a scripting language: it has a (primitive) IDE when you can type a few lines of code and hit Run without even having to save the file. Actually it wraps the code around a class and adds a main() call, compiles it and run it in a window.
Lot of people use it for real-time exhibitions (VJ and similar).
It has the power and limitations of Java, but adds out of the box a number of nice wrappers (libraries) to simplify access to Java2D, OpenGL, SVG, etc.
Somehow, it has become a model of simple graphics language: there are several applications trying to mimic Processing in other languages, like Ruby, Scala or Python. One of the most impressive is a JavaScript implementation, using the canvas component implemented in Firefox, Safari, Opera, etc.
I vote c++0x. Partial support is already available in gcc-4.3+ using the -std=c++0x flag.
Would 'C' be too obvious an answer?
I have very successfully used C++ for the engine, with the application written in Lua on top. JavaScript is also very practical, now the latest generation of JIT based JS engines are around (tracemonkey, V8 etc).
I think C++ will be with us for a while yet; even Tim Sweeney hasn't actually switched to Haskell (pdf) yet, AFAIK :-)
Java and LWJGL (OpenGL wrapper) has worked well for me. If you're looking for more of a scene graph type library like Orge have a look at jMonkeyEngine which we used to create a google earth type application (see www.skapeworld.com). If you're sensible with object creation the garbage collection is a non issue.
If your target is a PC, I think you can try C#, or embed Lua in your C++ app and run scripts for 'high-level' stuff. However if your target is a console, you must manage your own memory!
Objective-C looks like a good match for your requirements (the latest version with optional GC), although it is too dynamic and Smalltalk-like for my taste.
XNA is your best bet I think. Being supported by the .NET framework you can build for a Windows or Xbox 360 platform by simply changing a setting in Game Studio. Best yet, all the tools are free!
If you decide to go with XNA you can easily get started using their quickstart guide
XNA Quickstart guide
It has been a rewarding and fun experiance for me so far, and a nice break from the memory management of C++.
Garbage collection is a must (as is
the ability to avoid its use when
necessary)
You can't disable a garbage collector temporarily. You would need a deterministic garbage collector then. But such a beast does come with a performance hit also. I think BEA JRockit is such a beast and then you should stick to Java.
Just to comment on your example; typedef is your friend...
typedef std::vector<Thingy> Thingys;
Thingys::const_iterator it = lotsOfThingys.begin()
Don't overlook independent languages in your quest. Emergence BASIC from Ionic Wind Software has a built in DirectX 9 engine, supports OOP and can easily interface with C libraries.
http://www.ionicwind.com
James.
The best enviroment for your project is the one you get your task done in the fastest way possible. This - especially for 3D-graphics - includes libraries.
Depending on the task, you may get away with some minor directx hacking. Then you could use .NET and slimdx. Managed languages tend to be faster to programm and easier to debug.
Perhaps you need a really good 3D-engine? Try Ogre3D or Irrlicht. You need commercial grade quality (one might argue that Ogre3D offers that) - go for Cryengine or Unreal. With Ogre3D and Irrlicht you might uses .NET as well, though the ports are not always up to date and plugins are not as easyly included as in the C++ versions. For Cryengine/Unrealengine you won't have a real choice I guess.
You need it more portable? OpenGL for the rescue - though you might need some wrapper (e.g. SDL).
You need a GUI as well? wxWidgets, QT might be a possiblity.
You already have a toolchain? Your libraries need to be able to handle the file formats.
You want to write a library? C / C++ might be a solution, since most of the world can use C / C++ libraries. Perhaps with the use of COM?
There are still a lot of projects/libraries I did not mention (XNA, Boost, ...) and if you want to create some program that does not only display 3D-graphics, you might have other needs as well (Input, Sound, Network, AI, Database, GUI, ...)
To sum it up: A programming language is a tool to reach a goal. It has to be seen in the context of the task at hand. The task has its own needs and these needs may chose the language for you (e.g. you need a certain library to get a feature that takes long to programm and you can only access the library with language X).
If you need the one-does-nearly-all: try C++/CLI (perhaps in combination with C# for easier syntax).
Good question.
As for the 'making me type far too much', C++0x seems to address most of it
as mentioned:
auto it = lotsOfThingys.begin()) // ... deduce type, just like in *ML
VS2010beta implements this already.
As for the memory management - for efficiency - you will have to keep good track of memory allocations, with or without garbage collection (ie, make memory-pools, re-use allocated object sometimes) anyhow, so that eventually whether your environment is garbage collected or not, matters less. You'll have to explicitly call the gc() as well, to keep the memory from fragmenting.
Having consistent ways to manage memory is important anywhere.
RAII - is a killer feature of C++
Another thing - is that memory is just one resource, you still have to keep track of other resources with a GC, so RIAA.
Anyhow, C# - is a nice alternative in many respects, I find it a very nice language, especially the ability to write functional-style code in it (the cute lambda -> syntax, map/select 'LINQ' syntax etc), thus the possibility to write parallel code; while it's still a 'standard curly-brackets', when you (or your colleagues) need it.
Have a look to Delphi/Pascal Object and some exemples :
http://www.delphigamer.com or http://glscene.cjb.net/
You can look at Ada. There is no garbage collector but this language is oftenly used for real-time system needing high reliability. That means less debuging times for your 3D applications.
And, you can also look at Haskell, if you don't know the functional paradigm this language will look weird to you, but it's worth a bit of your time. Tim Sweeney (EPIC Inc) is considering this language as a C++ alternative.