Subscribe to GameFromScratch on YouTube Support GameFromScratch on Patreon

14. March 2012

 

 

In part 1 we look at a very basic example of sending information across the wire from SFML to NodeJS.  In part 2 we looked at JSON encoding high score data, that is then sent via UDP socket to a Node server.  Now we complete the process, by having Node return high score data back to your C++ SFML app.  By the end of this section, you will have all the code you need for a functioning ( if somewhat fragile ) high score client and server.

 

 

First we look at the C++ code.  Things are very similar to part 2, except code has been refactored a bit for re-use.  Lets look now.

 

 

#include "SFML/Network.hpp" #include "JSON.h" #include <iostream> void MakePacket(const wchar_t* action, const wchar_t * name, const float score, sf::Packet &packet) { JSONObject data; data[L"action"] = new JSONValue(action); data[L"name"] = new JSONValue(name); data[L"score"] = new JSONValue(score); JSONValue * val = new JSONValue(data); data.clear(); std::wstring dataString = val->Stringify(); delete val; std::string notSoWide; notSoWide.assign(dataString.begin(),dataString.end()); packet.Append(notSoWide.c_str(),notSoWide.length()); } int main(int argc, char* argv[]) { sf::IPAddress ip("127.0.0.1"); sf::SocketUDP socket; sf::Packet packet; unsigned short port = 1000; unsigned short respPort = 1001; if(argc == 1) { //No arguments means program should retrieve scores and print them MakePacket(L"GetScores",L"",0.0f,packet); socket.Bind(respPort); socket.Send(packet,ip,port); char buffer[512]; // The buffer to store raw response data in sf::IPAddress respIP; // The ip address where the response came from size_t respSize; // The amount of data actually written to buffer // Now receive a response. This is a blocking call, meaning your program // will hang until a response is received. socket.Receive(buffer,512,respSize,respIP,port); socket.Close(); std::string respString(buffer,respSize); // Now lets turn the string back into JSON JSONValue * jsonHighScores = JSON::Parse(respString.c_str()); if(!jsonHighScores->IsObject()) { std::cout << "Something went wrong, not good."; return -1; } JSONObject root = jsonHighScores->AsObject(); if(root.find(L"Scores") != root.end() && root[L"Scores"]->IsArray()) { JSONArray scores = root[L"Scores"]->AsArray(); std::cout << "Current high scores:" << std::endl; for(int i = 0; i < scores.size();i++) { JSONObject curObj = scores[i]->AsObject(); std::wcout << "Name:" << curObj[L"Name"]->AsString(); std::cout << " High Score:" << curObj[L"Score"]->AsNumber() << std::endl; } } delete jsonHighScores; } else if(argc == 3) { MakePacket(L"AddScore", std::wstring(argv[1],argv[1] + strlen(argv[1])).c_str(), atof(argv[2]), packet); if(socket.Send(packet,ip,port) != sf::Socket::Done) { std::cout << "An error ocurred sending packet" << std::endl; } socket.Close(); } else { std::cout << "Invalid usage, proper format is player name then score, for example:" << std::endl; std::cout << "Or run with no arguments to get a list of scores returned" << std::endl; std::cout << "Scoreboard \"Player Name\" 42" << std::endl; return -1; } return 0; }

Click here to download Scoreboard.cpp

 

 

We have reorganized slightly to use a set of if/else’s based on the number of parameters passed in.  The common code between the two handled conditions has been moved to the method MakePacket(), which contains nothing new from last part.  It’s the section where argc == 1 ( which means there were no parameters specified, as argc at 1 represents the executables name ) that we are interested in.  If the user runs the application from the command line with no parameters, we want to fetch the high scores from the server.

 

 

The request process is the same, although we are passing the action GetScores instead.  One key difference is we Bind our port.  Think of this action as say “Yo!  This port is ours!”.  Only one application per computer can have access to a given port.  This is why we run our server on 1000, but then bind our response port on 1001, since client and server on running on the same machine.  Unlike when we add a score, for GetScores we want to listen for a response, which is what we do with socket.Receive().  Keep in mind, this action blocks, so your program wont be able to continue until this is done.  There are alternatives ( like Selector ) if this behavior is undesirable.

 

 

Now assuming Receive() worked correctly ( which in the Real World™ you shouldn’t!), buffer will be full of our JSON encoded string, while respSize will represent the amount of buffer that was actually used.  Using these two pieces of information, lets create a string from only the meaningful bits ( the rest of the buffer will be full of gibberish ).  We now turn our string back into JSON ( in production code, I would extend the JSON library to work with standard strings ), and check to see if it is a valid JSON object, error out if it’s not.  Now it’s a matter of parsing out the JSON into meaningful form.  Remember that a JSONObject is actually just a STL map of key/value pairs, so we find our array of type JSONArray named Scores.  Each item in that array is in turn another map, so we loop through them all find the value for “Name” and “Score”, turn them back into their native type and display them out to the console.  And that’s about it.

 

 

Now lets take a look at the server side of things.  Here we made much less invasive changes, so lets just look at what has changed.  To see the fully modified server.js click here.  I no doubt forgot a small change here or there, I always do!

 

 

First we add another condition to the switch statement as follows:

 

case "GetScores": console.log("Get Scores called"); // Turn highscores back into a JSON encoded string var highScoreAsString = JSON.stringify(highScores); // Create a buffer to hold that string var responseBuffer = new Buffer(highScoreAsString.length); // Write the string to the buffer responseBuffer.write(highScoreAsString); // Send it back to the client, using the addressing information // passed in via rinfo server.send(responseBuffer,0,responseBuffer.length, rinfo.port,rinfo.address, function(err, sent){ if(err) console.log("Error sending response"); else console.log("Responded to client at " + rinfo.address + ":" + rinfo.port ); }); break;

 

 

The code is pretty much documented, the nutshell version is, we turn our high score information into a JSON encoded string, make a buffer large enough for the string, copy the string to the buffer, then call send to the address and port the request came from, as defined in rinfo.

 

 

Then, mostly because we can, we use Node to create an extremely simple high score web server, so if you visit this site with your browser you can get a current list of high scores.  Look how laughably easy that task is!

 

 

// Now, lets show off a bit, with the worlds simplest web server. // Dynamically creates webpage showing current high scores. var webServer = require('http'); webServer.createServer(function(req,res){ res.writeHead(200, {'Content-Type': 'text/html'}); res.write("<html><body><h1>High Scores</h1><ul>"); for(i=0;i < highScores.Scores.length;++i) { res.write(highScores.Scores[i].Name + "&nbsp;&nbsp;" + highScores.Scores[i].Score + "<br />"); } res.write("</ul></body></html>"); res.end(); }).listen(80);

 

 

 

And… that’s it!  So now, lets take a look at things in action.  Open a command prompt and launch your server.js in node.  Then in another command prompt run scoreboard.exe, like this:

 

 

Here is using Scoreboard from the command line:

image

 

 

And here is the server handling these requests:

 

image

 

 

Finally, fire up a web browser and hit 127.0.0.1 ( assuming you don’t have another webserver running on your machine ):

 

image

 

 

It ain’t pretty, but it is a fully functioning high score server.  All you need to do is add a layer of security, harden things a bit with an iota of fault tolerance, pretty things up a bit and you are set.

 

 

As always, you can download the complete project zip here.

Programming ,

9. March 2012

 EDIT: DO not use the included binaries, instead look at the link from the Pang tutorial series to your right!

 

I have gotten a few emails or messages on this topic, enough so that I figure I will put together a post on the subject.  In my PANG! SFML C++ game tutorial, I show how to configure for debug builds but not release.

 

 

So, first and foremost, you are going to need to compile SFML 1.6 for release mode if you don’t already have the release libraries.  You can either download the SFML 1.6  source code here and compile them for release, in either DLL or static mode.  To do so, in Visual Studio 2010 after importing the project ( from SFML-1.6\build\vc2008 ) go ahead and delete the samples folder in the Solution Explorer. Then select the Build Menu, go to the Configuration Manager, then select the build you want to make:

 

Untitled

 

 

You either want to build Release DLL or Release Static, depending on if you are compiling static or dynamic.  If that is completely alien to you what the difference is, dynamic means you will ship the SFML Dll’s with your application, which will contain the SFML related code.  Static on the other hand, will compile all of the SFML related code into your EXE file, making it quite large but easier to distribute.  Either works, but if you ran into the dreaded ATI bug, static fixes it.  On the other hand, if you don’t use all parts of the SFML library, dynamic can be a whole lot smaller.

 

 

If you can’t be bothered building the DLLs, I have compiled them for you.  This archive contains the .lib/dll files for both static and dll versions of SFML compiled for Visual Studio 2010.

 

 

Now that you have the proper lib and dll files, the instructions are basically identical to this part of the tutorial.   The only thing you have to do different is, when in your projects properties before adding libraries, you need to select Release Build.

 

image

 

 

Also, when you specify the library names, you do not include –d at the end.  So for example, instead of adding sfml-system-d.lib, you add sfml-system.lib.  Repeat this for each library.

 

Now you should be able to build the release version of your game without problem.  This again is accomplished using Build->Configuration Manager, like so:

 

image

 

 

Simply switch to release rebuild and done.

Programming

7. March 2012

 

 

Ok, I realize my definition of a week may vary from what you might traditionally expect.  When I started this concept I thought I would find things all the time, and winnowing it down to aPyBook single item would be the biggest challenge!  Hunting down cool things is trickier than I thought!  This “week” was quite easy, it was brought to my attention using the contact form on this site.  If you have something you think other developers ( and developers in training ) would be interested in, send it to me!

 

 

Anyways, enough about my apparent inability to tell time, on to the cool thing.  Are you interested in learning game programming but are intimidated by the gigantic mountain of details ahead of you?  I understand your frustration, it’s an overwhelming subject with so much to learn and so many options available to you, options that you really aren’t well equipped to answer yet.  This is why I put together my beginners guide and you may notice that one of the languages I suggested was Python, although that section was pretty sparse.  Well this item goes a long way towards fixing that.

 

 

Author Albert Sweigart has created not just one, but two Python books about learning to program games using python.  The first book teaches the Python language by building a number of classic “basic” games including Hangman, Tic Tac Toe and Reversi.  Then around chapter 17, he starts to address more advanced games using the popular Pygame library.  Three chapters is far too little time to deal with this subject, and clearly the author agrees, as the entirety of the second book is about using Python with PyGame. 

 

 

The second book creates much more advanced games, while still teaching Python concepts by example.  In this book you create a minesweeper-esque game, a SNAFU/Nibble clone, a 2D Katamari Damacy’ish with squirrels game, a box pusher type game and a handful more.  It is slightly more involved than the first book, but together you should have no problems with it. The author set out to write a book that a 12 year old could understand and I believe he has succeeded.

 

 

At this point you may be wonder why exactly I’ve featured these particular books, there are literally thousands of books out there.  Good question and how is this for an answer…  They are free!  Al has made both books available under the creative commons license completely free, by almost any definition of the word.  You can head over to InventWithPython.com and read either book online, or download them as PDF.  Absolutely no strings attached.

 

 

That said, if you are the type that prefers a physical book in your hands, or you want to reward the author for his hard work, both Invent Your Own Computer Game with Python and Making Games with Python and PyGame are both available on Amazon, for less than 25$.  Looking at the reviews, it seems both of this books accomplished what they set out to do.

 

 

So, if you are just starting out or are picking up the Python language, these two books are a very good place to start.  Really, at a grand total price tag of 0$, what have you got to lose?

Cool Thing of the Week

7. March 2012

 

 

Back in November, Sony rather shockingly announced the closed beta of a C# based developer kit for PlayStation™Certified devices, which include their Xperia Play and moresony-playstation-vita importantly, the Playstation Vita and their as of yet unreleased Playstation tablet.  Then nothing… complete silence.  Rumour suggested a 1000$ price tag, which was reasonable in regards to a console development kit ( and downright cheap if you played Game Dev Story! ), but a rather steep price for your average indie developer.

 

 

Well, good news!  Today Sony announced an open beta in April, and more importantly, a 99$ annual price tag.  Here is the official press release:

 

 

Tokyo, March 7, 2012 – Sony Computer Entertainment Inc. (SCE) today announced that it will release the open beta version of PlayStation®Suite SDK*1 to content developers in April 2012 and the official version later this year. Through the introduction of these SDKs, SCE will offer a more streamlined content development environment for content developers — from large game development companies to small, independent shops — and further expand the world of PlayStation® to open operating system based portable devices.

In November 2011, SCE released the closed beta version of PlayStation®Suite SDK to limited content developers in Japan, United States and the United Kingdom. The upcoming open beta version incorporates their feedback and will dramatically enhance convenience and efficiency of the content development environment. The phased rollout of the open beta version will start in April 2012 free of charge and expand target countries beyond Japan, United States and the United Kingdom. Developers will also be able to conduct performance verification of their content developed with the open beta version on PlayStation®Vita.

SCE will also release the official version of PlayStation®Suite SDK at $99 US annually later this year, allowing content developers to have their content distributed through PlayStation®Store*2 on a commercial basis. Through the official version, content developers will also be able to seamlessly continue to develop content which was created with the open beta or the closed beta versions.

Furthermore, SCE will be adding content for PlayStation®Suite in Japan, United States, Canada, United Kingdom, France, Italy, Germany, Spain, and Australia. The phased rollout of the update will start later this year. The phased rollout will include improving the PlayStation®Suite presence on PlayStation®Store for users who want to enjoy a variety of content with ease and convenience on their PlayStation™Certified devices. SCE will also deliver content created through the official version of PlayStation®Suite SDK after the necessary procedure is completed.

As of March 7, 2012, the line-up of PlayStation™Certified devices include Xperia™ arc, Xperia™ acro, Xperia™ PLAY, Xperia™ acro HD, Xperia™ S, Xperia™ ion*3 from Sony Mobile Communications AB, and "Sony Tablet" S and "Sony Tablet" P from Sony Corporation. SCE will continue to further accelerate the expansion of PlayStation™Certified devices.

Through PlayStation®Suite, SCE will deploy various measures to support content developers in their business, and expand the PlayStation® entertainment experience on an open operating system.

※1 Software Development Kit is a set of development tools and software libraries. Developers are able to obtain this SDK by signing a license agreement with SCE.

※2 Users can download vast digital content including games through PlayStation Store for PS3, PSP, PS Vita and PS Certified devices.

※3 Model name may vary by region. Sales area may vary by model.

 

 

This news isn’t just confined to Sony devices.  Back in February HTC announced that they would be releasing Playstation certified mobile phones.  This may in fact be the movement that finally brings gaming to Android.

 

Truly a great time to be a small budget developer!

News

5. March 2012

 

 

This thread just showed up on reddit, announcing that Unity 3D Basic for Android and iOS are being offered for free until April 8th.  Considering each costs 400$, and how awesome Unity is, this is amazing news if true!

 


Truth is, I go to Unity’s store I get:

image

 

 

Then again, giving away 800$ worth of amazing software for free will cause that, no?  If you haven’t used Unity in the past, now is a very good time to check it out ( well… when the site comes back online ), it is a very impressive game engine.

 

 

So, hopefully this is true, I will keep an eye on the site and hopefully it will come back online.  If this is in fact true, you should jump all over it!  I will update here once I confirm if this is true or not.

 

 

EDIT1:

 

From Unity3d’s twitter feed:

 

image

 

So, unless they got hacked, this deal is looking to be very legit!  I think for a great many people considering targeting iOS or Android, Unity just became a much more likely engine.  Although in the grand scheme of things, 800$ isn’t all that much, it’s enough of a barrier of entry to stop many people.

 

Again, will update once I manage to connect to the store and see it for myself!

 

 

 

EDIT2:  It’s Legit!

image

 

Go get it!

News

Month List

Popular Comments