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  • What programming concept is used in Nokia Lumina City Lens application [closed]

    - by gowri
    I am totally impressed about the Nokia City Lens application. How does the Nokia Lumia City Lens app work? Nokia Lumia City Lens app detects shops, restaurants, etc. by scanning the visual environment. But how can it detect shops or anything by only scanning visual information? Because we need a 360 degree view to detect a location. Because we can't simply match visual information and get that data. The visuals will change proportionally with distance and angle. So how does this app match the location and retrieve the information? Can anyone explain the concept What technology or algorithm is used in this app?

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  • DDDNorth2 Bradford, 13th October 2012 - Async Patterns presentation and source code

    - by Liam Westley
    Many thanks to Andy Westgarth and his team for organising a fantastic conference at the rather elegant Bradford University School of Management. Also, a big congratulations to all the delegates who gave up there free time to come and hear us speak and who were, in general, enthusiastic and asked some cracking questions to keep us speakers on our toes. For those who attended my Async my source code and presentation are now available on GitHub, https://github.com/westleyl/DDDNorth2-AsyncPatterns If you are new to Git then the easiest client to install is GitHub for Windows, a graphical UI for accessing GitHub. Personally, I also have TortoiseGit installed – the file explorer add-in that works in a familiar manner to TortoiseSVN. As I mentioned during the presentation I have not included the sample data, the music files, in the source code placed on GitHub but I have included instructions on how to download them from http://silents.bandcamp.com and place them in the correct folders. What I forgot to mention is that Windows Media Player by default does not play Ogg Vorbis and Flac music files, however you can download the codec installer for these, for free, from http://xiph.org/dshow. I am planning to break down this little project into a series of blog posts, with each pattern being a single blog post over several weeks. In these I will flesh out the background behind the pattern, the basic goal being achieved and how to monitor the progress of the sample data being processed. Basically, what I said during the presentation and is missing from the slides.

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  • How can I generate signed distance fields (2D) in real time, fast?

    - by heishe
    In a previous question, it was suggested that signed distance fields can be precomputed, loaded at runtime and then used from there. For reasons I will explain at the end of this question (for people interested), I need to create the distance fields in real time. There are some papers out there for different methods which are supposed to be viable in real-time environments, such as methods for Chamfer distance transforms and Voronoi diagram-approximation based transforms (as suggested in this presentation by the Pixeljunk Shooter dev guy), but I (and thus can be assumed a lot of other people) have a very hard time actually putting them to use, since they're usually long, largely bloated with math and not very algorithmic in their explanation. What algorithm would you suggest for creating the distance fields in real-time (favourably on the GPU) especially considering the resulting quality of the distance fields? Since I'm looking for an actual explanation/tutorial as opposed to a link to just another paper or slide, this question will receive a bounty once it's eligible for one :-). Here's why I need to do it in real time: There's something else:

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  • How are trajectories calculated and transmitted to other players in Multi-Player ?

    - by giulio
    I play alot of COD4. And can see tracers for gunfire, missles, care packages fall from helicopters etc. There is alot of activity. I am curious to know the algorithm (at a high level) that manages all this action when you have 20 people on a map shooting each other to death ? This question touches on the subject but doesn't ask for a more in-depth answer as to how you the developers go about calculating and transmitting movement and collision detection for projectiles, be it missles/bullets or any other object that is flying through the air in real-time.

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  • How to document and teach others "optimized beyond recognition" computationally intensive code?

    - by rwong
    Occasionally there is the 1% of code that is computationally intensive enough that needs the heaviest kind of low-level optimization. Examples are video processing, image processing, and all kinds of signal processing, in general. The goals are to document, and to teach the optimization techniques, so that the code does not become unmaintainable and prone to removal by newer developers. (*) (*) Notwithstanding the possibility that the particular optimization is completely useless in some unforeseeable future CPUs, such that the code will be deleted anyway. Considering that software offerings (commercial or open-source) retain their competitive advantage by having the fastest code and making use of the newest CPU architecture, software writers often need to tweak their code to make it run faster while getting the same output for a certain task, whlist tolerating a small amount of rounding errors. Typically, a software writer can keep many versions of a function as a documentation of each optimization / algorithm rewrite that takes place. How does one make these versions available for others to study their optimization techniques?

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  • Is acousting fingerprinting too broad for one audio file only?

    - by IBG
    So we were looking for some topics related to audio analysis and found acoustic fingerprinting. As it is, it seems like the most famous application for it is for identification of music. Enter our manager, who requested us to research and possible find an algorithm or existing code that we can use for this very simple approach (like it's easy, source codes don't show up like mushrooms): Always-on app for listening Compare the audio patterns to a single audio file (assume sound is a simple beep) If beep is detected, send notification to server With a flow this simple, do you think acousting fingerprinting is a broad approach to use? Should we stop and take another approach? Where to best start? We haven't started anything yet (on the development side) on this regard, so I want to get other opinion if this is pursuit is worth it or moot.

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  • About floating point precision and why do we still use it

    - by system_is_b0rken
    Floating point has always been troublesome for precision on large worlds. This article explains behind-the-scenes and offers the obvious alternative - fixed point numbers. Some facts are really impressive, like: "Well 64 bits of precision gets you to the furthest distance of Pluto from the Sun (7.4 billion km) with sub-micrometer precision. " Well sub-micrometer precision is more than any fps needs (for positions and even velocities), and it would enable you to build really big worlds. My question is, why do we still use floating point if fixed point has such advantages? Most rendering APIs and physics libraries use floating point (and suffer it's disadvantages, so developers need to get around them). Are they so much slower? Additionally, how do you think scalable planetary engines like outerra or infinity handle the large scale? Do they use fixed point for positions or do they have some space dividing algorithm?

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  • Tree position terminology/naming

    - by wst
    This is a naming things question. I am processing trees (XML documents), and there are often special rules applied to nodes based on structure. It's been very difficult coming up with concise naming conventions for some cases, namely for nodes in the first position among their siblings, along with some recursive relationship: Given an arbitrary node, I want to describe its first child, and then that node's first child, and so on recursively. Given another arbitrary node, I want to describe its parent if the parent is first among its siblings, and that parent's parent if it's first, and so on recursively. Is there existing terminology to describe these tree positions? How would you name a variable or function that captures one of these cases so that it's intuitive to an unfamiliar developer trying to understand an algorithm?

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  • Tips for building an AI for a 2D racing game

    - by declique
    I have a school project to build an AI for a 2D racing game in which it will compete with several other AIs (no collision). We are given a black and white bitmap image of the racing track, we are allowed to choose basic stats for our car (handling, acceleration, max speed and brakes) after we receive the map. The AI connects to the game's server and gives to it several times a second numbers for the current acceleration and steering. The language I chose is C++, by the way. The questions are: What is the best strategy or algorithm (since I want to try and win)? I currently have in mind some ideas found on the net and one or two of my own, but I would like before I start to code that my perspective is one of the best. What good books are there on that matter? What sites should I refer to?

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  • How would I batch rename a lot of files using command-line?

    - by Whisperity
    I have a problem which I am unable to solve: I need to rename a great dump of files using patterns. I tried using this, but I always get an error. I have a folder, inside with a lot of files. Running ls -1 | wc -l, it returns that I have like 160000 files inside. The problem is, that I wish to move these files to a Windows system, but most of them have characters like : and ? in them, which makes the file unaccessible on said Windows-based systems. (As a "do not solve but deal with" method, I tried booting up a LiveCD on the Windows system and moving the files using the live OS. Under that Ubuntu, the files were readable and writable on the mounted NTFS partition, but when I booted back on Windows, it showed that the file is there but Windows was unable to access it in any fashion: rename, delete or open.) I tried running rename 's/\:/_' * inside the folder, but I got Argument list too long error. Some search revealed that it happens because I have so many files, and then I arrived here. The problem is that I don't know how to alter the command to suit my needs, as I always end up having various errors like Trying find -name '*:*' | xargs rename : _, it gives xargs: unmatched single quote; by default quotes are special to xargs unless you use the -0 option [\n] syntax error at (eval 1) line 1, near ":" [\n] xargs: rename: exited with status 255; aborting Adding the -0 after xargs turns the error message to xargs: argument line too long These files are archive files generated by various PHP scripts. The best solution would be having a chance to rename them before they are moved to Windows, but if there is no way to do it, we might have a way to rename the files while they are moved to Windows. I use samba and proftpd to move the files. Unfortunately, graphical software are out of the question as the server containing the files is what it is, a server, with only command-line interface.

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  • Exalogic Elastic Cloud Software (EECS) version 2.0.1 available

    - by JuergenKress
    We are pleased to announce that as of today (May 14, 2012) the Exalogic Elastic Cloud Software (EECS) version 2.0.1 has been made Generally Available. This release is the culmination of over two and a half years of engineering effort from an extended team spanning 18 product development organizations on three continents, and is the most powerful, sophisticated and comprehensive Exalogic Elastic Cloud Software release to date. With this new EECS release, Exalogic customers now have an ideal platform for not only high-performance and mission critical applications, but for standardization and consolidation of virtually all Oracle Fusion Middleware, Fusion Applications, Application Unlimited and Oracle GBU Applications. With the release of EECS 2.0.1, Exalogic is now capable of hosting multiple concurrent tenants, business applications and middleware deployments with fine-grained resource management, enterprise-grade security, unmatched manageability and extreme performance in a fully virtualized environment. The Exalogic Elastic Cloud Software 2.0.1 release brings important new technologies to the Exalogic platform: Exalogic is now capable of hosting multiple concurrent tenants, business applications and middleware deployments with fine-grained resource management, enterprise-grade security, unmatched manageabi! lity and extreme performance in a fully virtualized environment. Support for extremely high-performance x86 server virtualization via a highly optimized version of Oracle VM 3.x. A rich, fully integrated Infrastructure-as-a-Service management system called Exalogic Control which provides graphical, command line and Java interfaces that allows Cloud Users, or external systems, to create and manage users, virtual servers, virtual storage and virtual network resources. Webcast Series: Rethink Your Business Application Deployment Strategy Redefining the CRM and E-Commerce Experience with Oracle Exalogic, 7-Jun@10am PT & On-Demand: ‘The Road to a Cloud-Enabled, Infinitely Elastic Application Infrastructure’ (featuring Gartner Analysts). WebLogic Partner Community For regular information become a member in the WebLogic Partner Community please visit: http://www.oracle.com/partners/goto/wls-emea ( OPN account required). If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Mix Forum Wiki Technorati Tags: ExaLogic Elastic Cloud,ExaLogic,WebLogic,WebLogic Community,Oracle,OPN,Jürgen Kress,ExaLogic 2.0.1

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  • Updated copy of the OBIEE Tuning whitepaper

    - by inowodwo
    The Product Assurance team have released an updated copy of the OBIEE Tuning Whitepaper. You can find it on the PA blog https://blogs.oracle.com/pa/entry/test or via Support note OBIEE 11g Infrastructure Performance Tuning Guide (Doc ID 1333049.1) https://support.us.oracle.com/oip/faces/secure/km/DocumentDisplay.jspx?id=1333049.1&recomm=Y This new revised document contains following useful tuning items: 1.    New improved HTTP Server caching algorithm. 2.    Oracle iPlanet Web Server tuning parameters. 3.    New tuning parameters settings / values for OPIS/OBIS components.

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  • Halloween: Season for Java Embedded Internet of Spooky Things (IoST) (Part 5)

    - by hinkmond
    So, here's the finished product. I have 8 networked Raspberry Pi devices strategically placed around our Oracle Santa Clara Building 21 office. I attached a JFET transistor based EMF sensor on each device to capture any strange fluctuations in the electromagnetic field (which supposedly, paranormal spirits can change as they pass by). And, I have have a Web app (embedded in this page) which can take the readings and show a graphical display in real-time. As you can see, all the Raspberry Pi devices are blinking away green, indicating they are all operational and all sensors are working correctly. But, I don't see anything... Darn... Maybe, I have to stare at the Web app for a while. I don't know when the "alleged" ghosts in our Oracle Santa Clara office are supposed to be active, but let me know if you see anything... Oh, and by the way, Happy Halloween from the Internet of Spooky Things! See the previous posts for the full series on the steps to this cool demo: Halloween: Season for Java Embedded Internet of Spooky Things (IoST) (Part 1) Halloween: Season for Java Embedded Internet of Spooky Things (IoST) (Part 2) Halloween: Season for Java Embedded Internet of Spooky Things (IoST) (Part 3) Halloween: Season for Java Embedded Internet of Spooky Things (IoST) (Part 4) Halloween: Season for Java Embedded Internet of Spooky Things (IoST) (Part 5) Hinkmond

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  • Redirect from the main page on multilanguage site

    - by Pluto
    I've decided to start developing multilingual web site. Now I'm thinking about the structure. The idea is to use a simple algorithm to find out what language is most interesting to the visitor when he makes his first visit to the root page, and then forward him to the corresponding address, for example, http://example.com/en/ for English-speaking audience and http://example.com/ru/ for Russians. The question is, how search engines react on such redirect? If this approach does not take away site's reputation, which redirects should I choose: 301 or 302? I would be very grateful for the reasoned response.

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  • Caching strategies - LRU, MRU, Clock-Pro

    - by golgofa
    I am going to write a bachelor's science work on caching strategies and really, can't find any links to specifications or full descriptions of some of them. Only something like summaries from wikipedia. Please, help with some links on LRU, MRU caching and new-one - Clock Pro. Thanks a lot. All links are very useful for me. The purpose of work - is to compare different cache strategies to get more effiency. It based on WebApplication with ejb 2.0, so algorithm's will be implemented there, espesially in ejbLoad() and ejbFindByPrimarKey(). Also, one of aspects of this application - it will use not common scheme of tables in database - it based on metamodel. So, if you had any experience on this topic, i would be grateful to take some of your knowledge)

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  • Problem graphics with ATI Radeon x1270 (RS690M) on Ubuntu 12.04

    - by Giuseppe Della Corte
    I'm Italian and so I apologize for my English! I'm a beginner to Ubuntu and I tried it on my desktop PC and it's fantastic, fast and fun! I decided to try it on my netbook Packard Bell DOT M/A and this is the configuration: AMD Athlon L110 1.2GHz 2GB of RAM ATI Radeon x1270 (RS690M) 150GB Hard Disk I installed Ubuntu 12.04 with Wubi (dualboot Windows 7 + Ubuntu 12.04), because the netbook does not have a DVD player! During the installation everything is OK, after it was installed I see mistakes in the graphical display! I see objects that are seen in different colors and moving (buttons, mouse pointer, text bar ... etc ...) At one point came not to see anything, such as this screenshot: The drivers are open, that is already installed in Ubuntu. Windows 7 video card runs fine, can run well Aero (transparent window effects), I can watch movies in HD and play some games with the Catalyst drivers from AMD. Now I ask a favor, you can help me solve this problem? Is there a fix for this driver or drivers different on the Internet? Thanks for your attention, good bye!

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  • What web oriented language would work best with binary data?

    - by Qqwy
    I want to create a service where people can upload files. However, since file storage costs money, I want to compress the files so they take less space. I would want to write my own compression algorithm, however, PHP doesn't have good ways to handle binary data (which is needed for many compression algorithms). So I wondered, what would be a better language to create such a website in? I have knowledge of PHP (and Javascript, HTML and CSS) but no experience with other things like Ruby, Perl, Python, and other web development languages.

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  • Inexpensive generation of hierarchical unique IDs

    - by romaninsh
    My application is building a hierarchical structure like this: root = { 'id': 'root', 'children': [ { 'name': 'root_foo', 'children': [] }, { 'id': 'root_foo2', 'children': [ { 'id': 'root_foo2_bar', 'children': [] } ] } ] } in other words, it's a tree of nodes, where each node might have child elements and unique identifier I call "id". When a new child is added, I need to generate a unique identifier for it, however I have two problems: identifiers are getting too long adding many children takes slower, as I need to find first available id My requirement is: naming of a child X must be determined only from the state in their ancestors When I re-generate tree with same contents, the IDs must be same or in other words, when we have nodes A and B, creating child in A, must not affect the name given to children of B. I know that one way to optimize would be to introduce counter in each node and append it to the names which will solve my performance issue, but will not address the issue with the "long identifiers". Could you suggest me the algorithm for quickly coming up with new IDs?

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  • k-d tree implementation [closed]

    - by user466441
    when i run my code and debugged,i got this error - this 0x00093584 {_Myproxy=0x00000000 _Mynextiter=0x00000000 } std::_Iterator_base12 * const - _Myproxy 0x00000000 {_Mycont=??? _Myfirstiter=??? } std::_Container_proxy * _Mycont CXX0017: Error: symbol "" not found _Myfirstiter CXX0030: Error: expression cannot be evaluated + _Mynextiter 0x00000000 {_Myproxy=??? _Mynextiter=??? } std::_Iterator_base12 * but i dont know what does it means,code is this #include<iostream> #include<vector> #include<algorithm> using namespace std; struct point { float x,y; }; vector<point>pointleft(4); vector<point>pointright(4); //we are going to implement two comparison function for x and y coordinates,we need it in calculation of median (we should sort vector //by x or y according to depth informaton,is depth even or odd. bool sortby_X(point &a,point &b) { return a.x<b.x; } bool sortby_Y(point &a,point &b) { return a.y<b.y; } //so i am going to implement to median finding algorithm,one for finding median by x and another find median by y point medianx(vector<point>points) { point temp; sort(points.begin(),points.end(),sortby_X); temp=points[(points.size()/2)]; return temp; } point mediany(vector<point>points) { point temp; sort(points.begin(),points.end(),sortby_Y); temp=points[(points.size()/2)]; return temp; } //now construct basic tree structure struct Tree { float x,y; Tree(point a) { x=a.x; y=a.y; } Tree *left; Tree *right; }; Tree * build_kd( Tree *root,vector<point>points,int depth) { point temp; if(points.size()==1)// that point is as a leaf { if(root==NULL) root=new Tree(points[0]); return root; } if(depth%2==0) { temp=medianx(points); root=new Tree(temp); for(int i=0;i<points.size();i++) { if (points[i].x<temp.x) pointleft[i]=points[i]; else pointright[i]=points[i]; } } else { temp=mediany(points); root=new Tree(temp); for(int i=0;i<points.size();i++) { if(points[i].y<temp.y) pointleft[i]=points[i]; else pointright[i]=points[i]; } } return build_kd(root->left,pointleft,depth+1); return build_kd(root->right,pointright,depth+1); } void print(Tree *root) { while(root!=NULL) { cout<<root->x<<" " <<root->y; print(root->left); print(root->right); } } int main() { int depth=0; Tree *root=NULL; vector<point>points(4); float x,y; int n=4; for(int i=0;i<n;i++) { cin>>x>>y; points[i].x=x; points[i].y=y; } root=build_kd(root,points,depth); print(root); return 0; } i am trying ti implement in c++ this pseudo code tuple function build_kd_tree(int depth, set points): if points contains only one point: return that point as a leaf. if depth is even: Calculate the median x-value. Create a set of points (pointsLeft) that have x-values less than the median. Create a set of points (pointsRight) that have x-values greater than or equal to the median. else: Calculate the median y-value. Create a set of points (pointsLeft) that have y-values less than the median. Create a set of points (pointsRight) that have y-values greater than or equal to the median. treeLeft = build_kd_tree(depth + 1, pointsLeft) treeRight = build_kd_tree(depth + 1, pointsRight) return(median, treeLeft, treeRight) please help me what this error means?

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  • Flowchart for solving programming problems

    - by nurne
    I noticed that every developer implements a somewhat different flowchart for solving programming problems. By flowchart I mean a defined system of techniques that the developer goes through in a certain sequence, trying to solve the problem at hand. Some examples for techniques: Google "how to..." or "... tutorial". Search the java/msdn/apple/etc API doc for the specific class or method. Search in stack overflow the exact problem with some tags like [iphone]/[java] etc. Take a nap and let the subconscious work. Debug. Draw the algorithm or system. Google the logged error message. Ask a colleague or manager. Ask a new question in stack overflow. From your experience, what is the best flowchart for solving a programming problem?

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  • How to implement the setup rules like Clash of Clan?

    - by user25959
    Now I'm already implement the setup build rules which the building could move by unit grid width and height. But the validation detection is poor efficiency. The algorithm cost me 10~12(ms) in average when I move the building. Here is my approach to that: 1.Basic Grid, it is a two dimensional array. Grid[row][column], so that I can save info for each grid. Like whether is it in occupied or excluded. 2.Exclude Space, this is a space which limit same building numbers in space.

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  • The how of a collision engine

    - by JXPheonix
    This is a very, very broad question - what is the general algorithm of how a collision engine works? No code in specific, but rather, just a general idea of how a collision engine does what it does, constantly refreshing the points of an object and comparing it to other objects? (see, I have the general gist of it here.) A collision engine is basically an engine used in games (generally) so that your player (call him Bob), whenever bob moves into a wall, Bob stops, Bob does not walk through the wall. They also generally handle the gravity in a game and environmental things like that.

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  • How can I generate signed distance fields in real time, fast?

    - by heishe
    In a previous question, it was suggested that signed distance fields can be precomputed, loaded at runtime and then used from there. For reasons I will explain at the end of this question (for people interested), I need to create the distance fields in real time. There are some papers out there for different methods which are supposed to be viable in real-time environments, such as methods for Chamfer distance transforms and Voronoi diagram-approximation based transforms (as suggested in this presentation by the Pixeljunk Shooter dev guy), but I (and thus can be assumed a lot of other people) have a very hard time actually putting them to use, since they're usually long, largely bloated with math and not very algorithmic in their explanation. What algorithm would you suggest for creating the distance fields in real-time (favourably on the GPU) especially considering the resulting quality of the distance fields? Since I'm looking for an actual explanation/tutorial as opposed to a link to just another paper or slide, this question will receive a bounty once it's eligible for one :-). Here's why I need to do it in real time:

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  • How to understand Linux kernel source code for a beginner?

    - by user16867
    I am a student interested in working on Memory Management, particularly the page replacement component of the linux kernel. What are the different guides that can help me to begin understanding the kernel source? I have tried to read the book Understanding the Linux Virutal Memory Manager by Mel Gorman and Understanding the Linux Kernel by Cesati and Bovet, but they do not explain the flow of control through the code. They only end up explaining various data structures used and the work various functions perform. This makes the code more confusing. My project deals with tweaking the page replacement algorithm in a mainstream kernel and analyse its performance for a set of workloads. Is there a flavor of the linux kernel that would be easier to understand(if not the linux-2.6.xx kernel)?

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  • How can I fix latency problems for car game?

    - by Freddy
    Basically I'm trying to make a online car racing game for IOS using Game Center real time multiplayer. I have setup a timer that sends data every 0.02 seconds to the other player with the current position and current angle. However sometimes, it will take LONGER then these 0.02 seconds for the package to be sent and then received. In this case i have implemented a method that "calculate" what the next position should be if no position is received based on the last position and angle. However, when the data then receives for let say 0.04 seconds after, it will change back to the last position, which will result in the car "jumping" back and lag. And If i just keep ignoring the data it will never take any input from the other user. Is their any way to prevent this? I suppose this needs to be fixed with some client-sided algorithm.

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