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  • Async Task in a loop

    - by Ankuj
    How does one create an AsyncTask which keeps running itself after a fixed interval of time. For eg. get data from server every 5 minutes and give notification to caller thread that it has received the data. I searched on the forum but could not find much. What I have gathered so far is that 1) A UI thread will call AsyncTask 2) onPrExecute for UI thread access before executing 3) OnPostExecute for UI thread access after executing I dont need to show any progress update to the user. Also, the task will be destroyed when the app closes. Any tutorial for this will he helpful

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  • Change value of adjacent vertices and remove self loop

    - by StereoMatching
    Try to write a Karger’s algorithm with boost::graph example (first column is vertice, other are adjacent vertices): 1 2 3 2 1 3 4 3 1 2 4 4 2 3 assume I merge 2 to 1, I get the result 1 2 3 2 1 1 3 4 2 1 3 4 3 1 2 4 4 2 3 first question : How could I change the adjacent vertices("2" to "1") of vertice 1? my naive solution template<typename Vertex, typename Graph> void change_adjacent_vertices_value(Vertex input, Vertex value, Graph &g) { for (auto it = boost::adjacent_vertices(input, g); it.first != it.second; ++it.first){ if(*it.first == value){ *(it.first) = input; //error C2106: '=' : left operand must be l-value } } } Apparently, I can't set the value of the adjacent vertices to "1" by this way The result I want after "change_adjacent_vertices_value" 1 1 3 1 1 1 3 4 2 1 3 4 3 1 2 4 4 2 3 second question : How could I pop out the adjacent vertices? Assume I want to pop out the consecutive 1 from the vertice 1 The result I expected 1 1 3 1 3 4 2 1 3 4 3 1 2 4 4 2 3 any function like "pop_adjacent_vertex" could use?

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  • how to declare object variable name in loop

    - by user3717895
    public class Node{ Node p,l,r; int height; String s; { /** class body**/ } } String[] S=new String[5000]; int i=0; while (i<5000){ Node x=new Node(); x=S[i]; } I want to make 5000 Node object. above code assign same variable name x every time but i want different variable name . then how to declare 5000 class variable name without declaring it manually. is there something by which i can create 5000 Node class object with ease.

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  • Returning Value of Radio Button Jquery [migrated]

    - by Jerry Walker
    I am trying to figure out why, when I run this code, I am getting undefined for my correct answers. $(document).ready (function () { // var answers = [["Fee","Fi","Fo"], ["La","Dee","Da"]], questions = ["Fee-ing?", "La-ing?"], corAns = ["Fee", "La"]; var counter = 0; var $facts = $('#main_ .facts_div'), $question = $facts.find('.question'), $ul = $facts.find('ul'), $btn = $('.myBtn'); $btn.on('click', function() { if (counter < questions.length) { $question.text(questions[counter]); var ansstring = $.map(answers[counter], function(value) { return '<li><input type="radio" name="ans" value="0"/>' + value + '</li>'}).join(''); $ul.html(ansstring); var currentAnswers = $('input[name="ans"]:checked').map(function() { return this.val(); }).get(); var correct = 0; if (currentAnswers[counter]==corAns[counter]) { correct++; } } else { $facts.text('You are done with the quiz ' + correct); $(this).hide(); } counter++; }); // }); It is quite long and I'm sorry about that, but I don't really know how tostrip it down. I also realize this isn't the most elegant way to do this, but I just want to know why I can't seem to get my radio values. I will add the markup as well if anyone wants.

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  • What are some ways to separate game logic from animations and the draw loop?

    - by TMV
    I have only previously made flash games, using MovieClips and such to separate out my animations from my game logic. Now I am getting into trying my hand at making a game for Android, but the game programming theory around separating these things still confuses me. I come from a background of developing non game web applications so I am versed in more MVC like patterns and am stuck in that mindset as I approach game programming. I want to do things like abstract my game by having, for example, a game board class that contains the data for a grid of tiles with instances of a tile class that each contain properties. I can give my draw loop access to this and have it draw the game board based on the properties of each tile on the game board, but I don't understand where exactly animation should go. As far as I can tell, animation sort of sits between the abstracted game logic (model) and the draw loop (view). With my MVC mindset, it's frustrating trying to decide where animation is actually supposed to go. It would have quite a bit of data associated with it like a model, but seemingly needs to be very closely coupled with the draw loop in order to have things like frame independent animation. How can I break out of this mindset and start thinking about patterns that make more sense for games?

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  • What's the best way to handle numerous recurring log entries in game loop?

    - by Kaa
    I have a custom logging system, use of which is scattered all over the engine and game. The system is linked to a "LogStore" that has an std::vector<string> logs[NUM_LOG_TYPES] - each vector corresponds with it's log type (info, error, debug, etc.). There's one extra std::vector that has "coordinates" to all log entries in the order they were received. Now, all the logging output is also displayed inside my development console in the game. The game console is handled by HTML-type GUI and therefore requires a new <p> element being added for each log output. My problem is that the log entries that are generated in the main loop each frame freeze the engine, because they continue to add elements to the in-game console, and if the console or guy generates a warning - that creates an infinite logging loop. I want to solve it by handling the recurring log entries in an elegant way that lets you know that something is critically wrong, but won't freeze the engine - like displaying the count of errors in the last 60 frames instead of displaying errors themselves. But how do you guys handle this? Does anyone know any nifty tricks to do this? I understand the question may sound vague, but if someone came across this type of issue I'm sure they would know exactly what's happening. Example problematic log entries: OpenGL warnings (I actually do check for errors every frame in many places) Really any prints anywhere in the main loop (may be debugging, may be warnings)

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  • Lot's of errors by insserv on apt-get operations after trying to install tomcat

    - by yankee
    I wanted to install tomcat on my Debian 6.0.4 machine. I tried apt-get install tomcat6-user which worked fine. But then I changed my mind about the user installation and wanted to install the package tomcat6. This resulted in a bunch of errors (see below). Now whatever I try to do with apt-get or with aptitude (trying to remove tomcat6-user, trying to remove tomcat6, trying to perform an apt-get upgrade,...) just results in the same list of errors. How did I manage that? And how can I fix it? # apt-get install tomcat6 Reading package lists... Done Building dependency tree Reading state information... Done The following extra packages will be installed: authbind Suggested packages: tomcat6-docs tomcat6-admin tomcat6-examples libtcnative-1 The following NEW packages will be installed: authbind tomcat6 0 upgraded, 2 newly installed, 0 to remove and 32 not upgraded. Need to get 56.6 kB of archives. After this operation, 442 kB of additional disk space will be used. Do you want to continue [Y/n]? Get:1 http://mirror.hetzner.de/debian/packages/ squeeze/main authbind amd64 1.2.0 [17.3 kB] Get:2 http://mirror.hetzner.de/debian/security/ squeeze/updates/main tomcat6 all 6.0.35-1+squeeze2 [39.3 kB] Fetched 56.6 kB in 0s (441 kB/s) Preconfiguring packages ... Selecting previously deselected package authbind. (Reading database ... 34717 files and directories currently installed.) Unpacking authbind (from .../authbind_1.2.0_amd64.deb) ... Selecting previously deselected package tomcat6. Unpacking tomcat6 (from .../tomcat6_6.0.35-1+squeeze2_all.deb) ... Processing triggers for man-db ... Setting up authbind (1.2.0) ... Setting up tomcat6 (6.0.35-1+squeeze2) ... Creating config file /etc/default/tomcat6 with new version Adding system user `tomcat6' (UID 108) ... Adding new user `tomcat6' (UID 108) with group `tomcat6' ... Not creating home directory `/usr/share/tomcat6'. insserv: warning: script 'S99iptables-custom' missing LSB tags and overrides insserv: warning: script 'iptables-custom' missing LSB tags and overrides insserv: There is a loop at service iptables-custom if started insserv: There is a loop between service rmnologin and mountnfs if started insserv: loop involving service mountnfs at depth 6 insserv: loop involving service networking at depth 5 insserv: loop involving service kbd at depth 9 insserv: There is a loop between service rmnologin and mountall-bootclean if started insserv: loop involving service mountall-bootclean at depth 5 insserv: loop involving service mountall at depth 4 insserv: There is a loop between service iptables-custom and lvm2 if started insserv: loop involving service lvm2 at depth 2 insserv: loop involving service udev at depth 1 insserv: There is a loop at service rmnologin if started insserv: There is a loop between service iptables-custom and checkroot if started insserv: loop involving service checkroot at depth 2 insserv: loop involving service keyboard-setup at depth 1 insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Max recursions depth 99 reached insserv: loop involving service courier-imap-ssl at depth 1 insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: loop involving service hwclockfirst at depth 2 insserv: loop involving service mountoverflowtmp at depth 9 insserv: loop involving service checkfs at depth 6 insserv: loop involving service mdadm-raid at depth 4 insserv: loop involving service hostname at depth 3 insserv: There is a loop between service iptables-custom and ifupdown-clean if started insserv: loop involving service ifupdown-clean at depth 5 insserv: There is a loop between service rmnologin and mountall if started insserv: There is a loop between service iptables-custom and mountdevsubfs if started insserv: loop involving service mountdevsubfs at depth 1 insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: loop involving service mtab at depth 6 insserv: There is a loop between service rmnologin and mountoverflowtmp if started insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: exiting now without changing boot order! update-rc.d: error: insserv rejected the script header dpkg: error processing tomcat6 (--configure): subprocess installed post-installation script returned error exit status 1 configured to not write apport reports Errors were encountered while processing: tomcat6 E: Sub-process /usr/bin/dpkg returned an error code (1)

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  • How can I increment a counter every N loops in JMeter?

    - by Dave Hunt
    I want to test concurrency, and reliably replicate an issue that JMeter brought to my attention. What I want to do is set a unique identifier (currently the time in milliseconds with a counter appended) and increment the counter between loops but not between threads. The idea being that the number of threads I have set up is the number of identical identifiers before incrementing and using another. If I had 3 threads with a loop count of 2 I want: 1. Unique ID: <current-time-in-millis>000000 2. Unique ID: <current-time-in-millis>000000 3. Unique ID: <current-time-in-millis>000000 4. Unique ID: <current-time-in-millis>000001 5. Unique ID: <current-time-in-millis>000001 6. Unique ID: <current-time-in-millis>000001 I've tried using Throughput Controllers to increment a counter, as well as several other things that seemed they should work but had no luck. This seems like something JMeter should be able to do. Is there any way to get the value of the loop count?

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  • Why does max-width behave counter intuitively on columns in a table? [migrated]

    - by Nate
    Basically, I have a stretchy table, I want my label column to be fixed width and my data column to be dynamically sized. My inclination would be to set the max-width via CSS on my label column. However, this has the opposite effect. I've created a jsfiddle that replicates this. (Re-size the window to see the left column dynamically sized and the right column fixed size) On my own site, I see the same behavior and it happens in IE and Chrome. If I switch it, and set max-width on the data column, everything behaves as I want, but it feels backwards to me. Am I doing something wrong here?

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  • Input handling between game loops

    - by user48023
    This may be obvious and trivial for you but as I am a newbie in programming I come with a specific question. I have three loops in my game engine which are input-loop, update-loop and render-loop. Update-loop is set to 10 ticks per second with a fixed timestep, render-loop is capped at around 60 fps and the input-loop runs as fast as possible. I am using one of the Javascript frameworks which provide such things but it doesn't really matter. Let's say I am rendering a tile map and the view of which elements are rendered depends on camera-like movement variables which are modified during key pressing. This is only about camera/viewport and rendering, no game physics involved here. And now, how can I handle input events among these loops to keep consistent engine reaction? Am I supposed to read the current variable modified with input and do some needed calculations in a update-loop and share the result so it could be interpolated in a render-loop? Or read the input effect directly inside the render-loop and put needed calculations inside? I thought interpreting user input inside an update-loop with a low tick rate would be inaccurate and kind of unresponsive while rendering with interpolation in the final view. How it is done properly in games overall?

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  • Xbox : la prochaine console sera baptisée Loop, plus petite et moins chère, elle sera sous Windows 9 avec un processeur ARM

    Xbox : la prochaine console sera baptisée Loop, Plus petite et moins chère, elle sera sous Windows 9 avec un processeur ARMe Ça devient presque une coutume pour certains produits de Microsoft dont la firme se garde de divulguer toute information officielle. Comme c'était le cas pour Windows 8, les rumeurs sur la prochaine console Xbox font à leur tour le « buz » sur la toile. Selon un article du site MSNerd, le successeur de la Xbox 360 pourrait être baptisé Xbox 720, et aura pour nom de code « Loop ». Plus petite et moins couteuse, cette console fonctionnera sous une version adaptée de Windows 9, avec un ...

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  • Why do most of us use 'i' as a loop counter variable?

    - by kprobst
    Has anyone thought about why so many of us repeat this same pattern using the same variable names? for (int i = 0; i < foo; i++) { // ... } It seems most code I've ever looked at uses i, j, k and so on as iteration variables. I suppose I picked that up from somewhere, but I wonder why this is so prevalent in software development. Is it something we all picked up from C or something like that? Just an itch I've had for a while in the back of my head.

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  • What exercises counter the back pain of sitting at a computer for 15 hours a day? [on hold]

    - by Sam
    I work up to 15 hours a day (not everyday :)) programming. When I do this I get a very sore lower back. I don't want to spend $1000 on a special chair like Joel Spolsky says. I'm sure I'm not alone here. Has anybody encountered this and found an exercise/other method to combat it? Maybe somebody with more physical education than me about opposing muscle groups or something. PS (not working fifteen hours a day isn't an answer, it's how I work best) and it's not off topic as programming is about more than code - it's a verb.

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  • Why do most of us use 'i' as a loop counter variable?

    - by kprobst
    Has anyone thought about why so many of us repeat this same pattern using the same variable names? for (int i = 0; i < foo; i++) { // ... } It seems most code I've ever looked at uses i, j, k and so on as iteration variables. I suppose I picked that up from somewhere, but I wonder why this is so prevalent in software development. Is it something we all picked up from C or something like that? Just an itch I've had for a while in the back of my head.

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  • How to create a Request Specific Thread Safe Static int Counter?

    - by user960567
    In one of my server application I have a class that look like, class A { static int _value = 0; void DoSomething() { // a request start here _value = 0; _value++; // a request end here } // This method can be called many time during request void SomeAsyncMethods() { _value++; } } The problem is SomeAsyncMethods is async. Can be called many times. What I need when a request start set _value = 0 and then asynchrosnously increment this. After end of request I need the total. But the problem is that another request at the same time can access the class.

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  • How do I do a game loop in c99?

    - by linitbuff
    I'm having trouble with how to structure a game using c99. I've seen a few tutorials on making a game loop, but they are all done with c++ and classes. My main problem seems to be moving data around between the functions without creating a mess, and what stuff to put in what header files etc. Do I just do something similar to the c++ loops, and create a class-like header with a structure containing all items needed by more than one of the functions, along with the prototypes of said functions, and include the header in each function's header file? Then, in the main function, instantiate the structure and pass a pointer to it to every function in the loop? Is this ok, or is there a better way to do it, and are there any good 'c' specific tutorials available? Cheers

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  • Opinion on "loop invariants", and are these frequently used in the industry?

    - by Michael Aaron Safyan
    I was thinking back to my freshman year at college (five years ago) when I took an exam to place-out of intro-level computer science. There was a question about loop invariants, and I was wondering if loop invariants are really necessary in this case or if the question was simply a bad example... the question was to write an iterative definition for a factorial function, and then to prove that the function was correct. The code that I provided for the factorial function was as follows: public static int factorial(int x) { if ( x < 0 ){ throw new IllegalArgumentException("Parameter must be = 0"); }else if ( x == 0 ){ return 1; }else{ int result = 1; for ( int i = 1; i <= x; i++ ){ result*=i; } return result; } } My own proof of correctness was a proof by cases, and in each I asserted that it was correct by definition (x! is undefined for negative values, 0! is 1, and x! is 1*2*3...*x for a positive value of x). The professor wanted me to prove the loop using a loop invariant; however, my argument was that it was correct "by definition", because the definition of "x!" for a positive integer x is "the product of the integers from 1... x", and the for-loop in the else clause is simply a literal translation of this definition. Is a loop invariant really needed as a proof of correctness in this case? How complicated must a loop be before a loop invariant (and proper initialization and termination conditions) become necessary for a proof of correctness? Additionally, I was wondering... how often are such formal proofs used in the industry? I have found that about half of my courses are very theoretical and proof-heavy and about half are very implementation and coding-heavy, without any formal or theoretical material. How much do these overlap in practice? If you do use proofs in the industry, when do you apply them (always, only if it's complicated, rarely, never)?

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  • what is the best way to use loops to detect events while the main loop is running?

    - by yao jiang
    I am making an "game" that has pathfinding using pygame. I am using Astar algo. I have a main loop which draws the whole map. In the loop I check for events. If user press "enter" or "space", random start and end are selected, then animation starts and it will try to get from start to end. My draw function is stupid as hell right now, it works as expected but I feel that I am doing it wrong. It'll draw everything to the end of the animation. I am also detecting events in there as well. What is a better way of implementing the draw function such that it will draw one "step" at a time while checking for events? animating = False; while loop: check events: if not animating: # space or enter press will choose random start/end coords if enter_pressed or space_pressed: start, end = choose_coords route = find_route(start, end) draw(start, end, grid, route) else: # left click == generate an event to block the path # right click == user can choose a new destination if left_mouse_click: gen_event() reroute() elif right_mouse_click: new_end = new_end() new_start = current_pos() route = find_route(new_start, new_end) draw(new_start, new_end, grid, route) # draw out the grid def draw(start, end, grid, route_coord): # draw the end coords color = red; pick_image(screen, color, width*end[1],height*end[0]); pygame.display.flip(); # then draw the rest of the route for i in range(len(route_coord)): # pausing because we want animation time.sleep(speed); # get the x/y coords x,y = route_coord[i]; event_on = False; if grid[x][y] == 2: color = green; elif grid[x][y] == 3: color = blue; for event in pygame.event.get(): if event.type == pygame.MOUSEBUTTONDOWN: if event.button == 3: print "destination change detected, rerouting"; # get mouse position, px coords pos = pygame.mouse.get_pos(); # get grid coord c = pos[0] // width; r = pos[1] // height; grid[r][c] = 4; end = [r, c]; elif event.button == 1: print "user generated event"; pos = pygame.mouse.get_pos(); # get grid coord c = pos[0] // width; r = pos[1] // height; # mark it as a block for now grid[r][c] = 1; event_on = True; if check_events([x,y]) or event_on: # there is an event # mark it as a block for now grid[y][x] = 1; pick_image(screen, event_x, width*y, height*x); pygame.display.flip(); # then find a new route new_start = route_coord[i-1]; marked_grid, route_coord = find_route(new_start, end, grid); draw(new_start, end, grid, route_coord); return; # just end draw here so it wont throw the "index out of range" error elif grid[x][y] == 4: color = red; pick_image(screen, color, width*y, height*x); pygame.display.flip(); # clear route coord list, otherwise itll just add more unwanted coords route_coord_list[:] = [];

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  • Help with game development. Render loop?

    - by John
    Hello, I'm working on a simple game, this is my first game project. Most of the samples I find have a Render Loop where all the game logic is made too and I just don't like this. Let's say I have a ball with X=0, and a wall in X=10 and in a slow machine, the first loop places the ball in X=7 and in a second loop, it places the ball in X=14. It would just crash the game! Is this "render loop" the right way to make games? Should I write code to check for things like this in every frame? Example, new frame X=14, last frame have X=7, so I should check if there's anything from X=7 to X=14?? I was thinking that I should have a separated thread for the game logic and in the render loop, I should just "take a snapshot" of the current game logic and display that, no? How do you guys, experienced game developers work around this? thanks!

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  • How to do the processing and keep GUI refreshed using databinding?

    - by macias
    History of the problem This is continuation of my previous question How to start a thread to keep GUI refreshed? but since Jon shed new light on the problem, I would have to completely rewrite original question, which would make that topic unreadable. So, new, very specific question. The problem Two pieces: CPU hungry heavy-weight processing as a library (back-end) WPF GUI with databinding which serves as monitor for the processing (front-end) Current situation -- library sends so many notifications about data changes that despite it works within its own thread it completely jams WPF data binding mechanism, and in result not only monitoring the data does not work (it is not refreshed) but entire GUI is frozen while processing the data. The aim -- well-designed, polished way to keep GUI up to date -- I am not saying it should display the data immediately (it can skip some changes even), but it cannot freeze while doing computation. Example This is simplified example, but it shows the problem. XAML part: <StackPanel Orientation="Vertical"> <Button Click="Button_Click">Start</Button> <TextBlock Text="{Binding Path=Counter}"/> </StackPanel> C# part (please NOTE this is one piece code, but there are two sections of it): public partial class MainWindow : Window,INotifyPropertyChanged { // GUI part public MainWindow() { InitializeComponent(); DataContext = this; } private void Button_Click(object sender, RoutedEventArgs e) { var thread = new Thread(doProcessing); thread.IsBackground = true; thread.Start(); } // this is non-GUI part -- do not mess with GUI here public event PropertyChangedEventHandler PropertyChanged; public void OnPropertyChanged(string property_name) { if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs(property_name)); } long counter; public long Counter { get { return counter; } set { if (counter != value) { counter = value; OnPropertyChanged("Counter"); } } } void doProcessing() { var tmp = 10000.0; for (Counter = 0; Counter < 10000000; ++Counter) { if (Counter % 2 == 0) tmp = Math.Sqrt(tmp); else tmp = Math.Pow(tmp, 2.0); } } } Known workarounds (Please do not repost them as answers) Those two first are based on Jon ideas: pass GUI dispatcher to library and use it for sending notifications -- why it is ugly? because it could be no GUI at all give up with data binding COMPLETELY (one widget with databinding is enough for jamming), and instead check from time to time data and update the GUI manually -- well, I didn't learn WPF just to give up with it now ;-) and this is mine, it is ugly, but simplicity of it kills -- before sending notification freeze a thread -- Thread.Sleep(1) -- to let the potential receiver "breathe" -- it works, it is minimalistic, it is ugly though, and it ALWAYS slows down computation even if no GUI is there So... I am all ears for real solutions, not some tricks.

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  • Drupal incorrectly escapes tags in javascript

    - by sergdev
    I installed drupal-6.16. I applied the patch from the post http://drupal.org/node/222926#comment-930745. It works correctly in simple cases. But following code of counter is handled incorrectly and counter is now displayed on the page after drupal. Drupal modifies the string "alt='1Gb.ua counter' /><\/a>")</a></script> to "alt='1Gb.ua counter' />&lt;\/a>")</a></script> The full code of counter follows: <br><br> Text <br><br> <!-- counter.1Gb.ua --> <script language="javascript" type="text/javascript"> cgb_js="1.0"; cgb_r=""+Math.random()+"&r="+ escape(document.referrer)+"&pg="+ escape(window.location.href); document.cookie="rqbct=1; path=/"; cgb_r+="&c="+ (document.cookie?"Y":"N"); </script><script language="javascript1.1" type="text/javascript"> cgb_js="1.1";cgb_r+="&j="+ (navigator.javaEnabled()?"Y":"N")</script> <script language="javascript1.2" type="text/javascript"> cgb_js="1.2"; cgb_r+="&wh="+screen.width+ 'x'+screen.height+"&px="+ (((navigator.appName.substring(0,3)=="Mic"))? screen.colorDepth:screen.pixelDepth)</script> <script language="javascript1.3" type="text/javascript"> cgb_js="1.3"</script> <script language="javascript" type="text/javascript">cgb_r+="&js="+cgb_js; document.write("<a href='http://www.1Gb.ua?cnt=1416'>"+ "<img src='http://counter.1Gb.ua/cnt.aspx?"+ "u=1416&"+cgb_r+ "&' border=0 width=88 height=31 "+ "alt='1Gb.ua counter'><\/a>")</script> <noscript><a href='http://www.1Gb.ua?cnt=1416'> <img src="http://counter.1Gb.ua/cnt.aspx?u=1416" border=0 width="88" height="31" alt="1Gb.ua counter"></a> </noscript> <!-- /counter.1Gb.ua --> Does anybody have this code working? How can it be fixed? Thanks a lot in advance!

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