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  • How are crossplatform/multiple-OS C++ projects planned in terms of code and tools?

    - by Nav
    I want to create a project in C++ that can work in Windows, Linux and Embedded Linux. How are projects created when they have to work across many OS'es? Is it first created on one OS and then the code slowly modified to be ported to another OS? Eg: to me, the Linux version of Firefox appears to be created as a Windows project and a separate Linux project with a different code base, since Firefox behaves a bit different in Windows and Linux. Although the source code download is surprisingly a single link. If QT is used for UI, Boost threads for threading, Build Bot for CI and NetBeans/Eclipse/QT Creator for an IDE, would a person be able to minimise the amount of code re-write required to get the project onto another OS? Is this the right way to do it, or are such projects meant to be created as two entirely separate projects for two separate OS'es?

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  • Business Case for investing time developing Stubs and BizUnit Tests

    - by charlie.mott
    I was recently in a position where I had to justify why effort should be spent developing Stubbed Integration Tests for BizTalk solutions. These tests are usually developed using the BizUnit framework. I assumed that most seasoned BizTalk developers would consider this best practice. Even though Microsoft suggest use of BizUnit on MSDN, I've not found a single site listing the justifications for investing time writing stubs and BizUnit tests. Stubs Stubs should be developed to isolate your development team from external dependencies. This is described by Michael Stephenson here. Failing to do this can result in the following problems: In contract-first scenarios, the external system interface will have been defined.  But the interface may not have been setup or even developed yet for the BizTalk developers to work with. By the time you open the target location to see the data BizTalk has sent, it may have been swept away. If you are relying on the UI of the target system to see the data BizTalk has sent, what do you do if it fails to arrive? It may take time for the data to be processed or it may be scheduled to be processed later. Learning how to use the source\target systems and investigations into where things go wrong in these systems will slow down the BizTalk development effort. By the time the data is visible in a UI it may have undergone further transformations. In larger development teams working together, do you all use the same source and target instances. How do you know which data was created by whose tests? How do you know which event log error message are whose?  Another developer may have “cleaned up” your data. It is harder to write BizUnit tests that clean up the data\logs after each test run. What if your B2B partners' source or target system cannot support the sort of testing you want to do. They may not even have a development or test instance that you can work with. Their single test instance may be used by the SIT\UAT teams. There may be licencing costs of setting up an instances of the external system. The stubs I like to use are generic stubs that can accept\return any message type.  Usually I need to create one per protocol. They should be driven by BizUnit steps to: validates the data received; and select a response messages (or error response). Once built, they can be re-used for many integration tests and from project to project. I’m not saying that developers should never test against a real instance.  Every so often, you still need to connect to real developer or test instances of the source and target endpoints\services. The interface developers may ask you to send them some data to see if everything still works.  Or you might want some messages sent to BizTalk to get confidence that everything still works beyond BizTalk. Tests Automated “Stubbed Integration Tests” are usually built using the BizUnit framework. These facilitate testing of the entire integration process from source stub to target stub. It will ensure that all of the BizTalk components are configured together correctly to meet all the requirements. More fine grained unit testing of individual BizTalk components is still encouraged.  But BizUnit provides much the easiest way to test some components types (e.g. Orchestrations). Using BizUnit with the Behaviour Driven Development approach described by Mike Stephenson delivers the following benefits: source: http://biztalkbddsample.codeplex.com – Video 1. Requirements can be easily defined using Given/When/Then Requirements are close to the code so easier to manage as features and scenarios Requirements are defined in domain language The feature files can be used as part of the documentation The documentation is accurate to the build of code and can be published with a release The scenarios are effective to document the scenarios and are not over excessive The scenarios are maintained with the code There’s an abstraction between the intention and implementation of tests making them easier to understand The requirements drive the testing These same tests can also be used to drive load testing as described here. If you don't do this ... If you don't follow the above “Stubbed Integration Tests” approach, the developer will need to manually trigger the tests. This has the following risks: Developers are unlikely to check all the scenarios each time and all the expected conditions each time. After the developer leaves, these manual test steps may be lost. What test scenarios are there?  What test messages did they use for each scenario? There is no mechanism to prove adequate test coverage. A test team may attempt to automate integration test scenarios in a test environment through the triggering of tests from a source system UI. If this is a replacement for BizUnit tests, then this carries the following risks: It moves the tests downstream, so problems will be found later in the process. Testers may not check all the expected conditions within the BizTalk infrastructure such as: event logs, suspended messages, etc. These automated tests may also get in the way of manual tests run on these environments.

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  • What issues lead people to use Japanese-specific encodings rather than Unicode?

    - by Nicolas Raoul
    At work I come across a lot of Japanese text files in Shift-JIS and other encodings. It causes many mojibake (unreadable character) problems for all computer users. Unicode was intended to solve this sort of problem by defining a single character set for all languages, and the UTF-8 serialization is recommended for use on the Internet. So why doesn't everybody switch from Japanese-specific encodings to UTF-8? What issues with or disadvantages of UTF-8 are holding people back? EDIT: The W3C lists some known problems with Unicode, could this be a reason too?

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  • Outline Shader Effect for Orthogonal Geometry in XNA

    - by Griffin
    I just recently started learning the art of shading, but I can't give an outline width to 2D, concave geometry when restrained to a single vertex/pixel shader technique (thanks to XNA). the shape I need to give an outline to has smooth, per-vertex coloring, as well as opacity. The outline, which has smooth, per-vertex coloring, variable width, and opacity cannot interfere with the original shape's colors. A pixel depth border detection algorithm won't work because pixel depth isn't a 3.0 semantic. expanding geometry / redrawing won't work because it interferes with the original shape's colors. I'm wondering if I can do something with the stencil/depth buffer outside of the shader functions since I have access to that through the graphics device. But I don't believe I'm able to manipulate actual values. How might I do this?

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  • How should I handle using two databases with a legacy PHP application?

    - by Toby Allen
    I have a legacy PHP application that was written in 2004 and uses MSSQL as a database backend. At this stage MSSQL is still supported by PHP but only just via a Microsoft driver. I have looked at converting to mysql via automated tools, which work quite well, but I have quite complex views which need a lot of individual work to convert. I don't have a great deal of time to do this. Many tools I wish to use and frameworks I would like to move the application to, don't support MSSQL, so I was considering adding new features using a new mysql database and wondered if anyone had opinions on the pros and cons of using two seperate database backends in a single application?

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  • how to bind data binding source to group radio buttons

    Hi I am working on windows c# application (visual studio 20008).In my form I have 5 Radio buttons ,grouped by group box. I have to bind this radio button to data binding source. this.rdoptPlus.DataBindings.Add(new Binding("Checked", MemberDefinitionsBindingSource, "UnaryOperator", true)); this.rdoptMinus.DataBindings.Add(new Binding("Checked", MemberDefinitionsBindingSource, "UnaryOperator", true)); i am unable to bind single datacolum to 5 radio buttons,please help me  read moreBy masuri suhasiniDid you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Broken links in content reports when tracking subdomains with Google Analytics

    - by Rob Sobers
    I have a tracking code that I use on my main site and my blog, which is on a subdomain: www.example.com blog.example.com I have a single profile in Google Analytics. I use advanced segments to look at traffic to the main site vs. traffic to the blog. Problem 1: When I'm browsing my content reports under Standard Reporting, the "Page" column doesn't show the top-level or sub-domain, so I can't differentiate www.example.com/index.html from blog.example.com/index.html easily. According to the docs, this filter is supposed to make GA prepend the hostname to the page URL in your content reports, but it doesn't seem to work. Problem 2: When I click on the little "Open in new window" icon next to a given page in a content report line, it always assumes the page lives on www.example.com, so I get 404s when the page is actually on blog.example.com. Is there a good solution for these subdomain tracking problems?

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  • Is it possible to remove a particular host key from SSH's known_hosts file?

    - by Kaustubh P
    I usually end up deleting the entire known_hosts file, which I have no problems for. But just out of curiosity, Is it possible to remove just a single entry? I opened the known_hosts file, and other han understanding that the file contains fingerprints for a given machine, I dont understand anything. Below is the message I faced, which led me to ask this question. Add correct host key in /home/wissen16/.ssh/known_hosts to get rid of this message. Offending key in /home/wissen16/.ssh/known_hosts:1 RSA host key for foo.com has changed and you have requested strict checking. Host key verification failed. Thanks.

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  • Simple solution now to a problem from 8 years ago. Use SQL windowing function

    - by Kevin Shyr
    Originally posted on: http://geekswithblogs.net/LifeLongTechie/archive/2014/06/10/simple-solution-now-to-a-problem-from-8-years-ago.aspxI remember having this problem 8 years ago. We had to find the top 5 donor per month and send out some awards. The SQL we came up with was clunky and had lots of limitation (can only do one year at a time), then switch the where clause and go again. Fast forward 8 years, I got a similar problem where we had to find the top 3 combination of 2 fields for every single day. And the solution is this elegant: SELECT CAST(eff_dt AS DATE) AS "RecordDate" , status_cd , nbr , COUNT(*) AS occurance , ROW_NUMBER() OVER (PARTITION BY CAST(eff_dt AS DATE) ORDER BY COUNT(*) DESC) RowNum FROM table1 WHERE RowNum < 4 GROUP BY CAST(eff_dt AS DATE) , status_cd , nbr If only I had this 8 years ago. :) Life is good now!

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  • Why do I get an exception when playing multiple sound instances?

    - by Boreal
    Right now, I'm adding a rudimentary sound engine to my game. So far, I am able to load in a WAV file and play it once, then free up the memory when I close the game. However, the game crashes with a nice ArgumentOutOfBoundsException when I try to play another sound instance. Specified argument was out of the range of valid values. Parameter name: readLength I'm following this tutorial pretty much exactly, but I still keep getting the aforementioned error. Here's my sound-related code. /// <summary> /// Manages all sound instances. /// </summary> public static class Audio { static XAudio2 device; static MasteringVoice master; static List<SoundInstance> instances; /// <summary> /// The XAudio2 device. /// </summary> internal static XAudio2 Device { get { return device; } } /// <summary> /// Initializes the audio device and master track. /// </summary> internal static void Initialize() { device = new XAudio2(); master = new MasteringVoice(device); instances = new List<SoundInstance>(); } /// <summary> /// Releases all XA2 resources. /// </summary> internal static void Shutdown() { foreach(SoundInstance i in instances) i.Dispose(); master.Dispose(); device.Dispose(); } /// <summary> /// Registers a sound instance with the system. /// </summary> /// <param name="instance">Sound instance</param> internal static void AddInstance(SoundInstance instance) { instances.Add(instance); } /// <summary> /// Disposes any sound instance that has stopped playing. /// </summary> internal static void Update() { List<SoundInstance> temp = new List<SoundInstance>(instances); foreach(SoundInstance i in temp) if(!i.Playing) { i.Dispose(); instances.Remove(i); } } } /// <summary> /// Loads sounds from various files. /// </summary> internal class SoundLoader { /// <summary> /// Loads a .wav sound file. /// </summary> /// <param name="format">The decoded format will be sent here</param> /// <param name="buffer">The data will be sent here</param> /// <param name="soundName">The path to the WAV file</param> internal static void LoadWAV(out WaveFormat format, out AudioBuffer buffer, string soundName) { WaveStream wave = new WaveStream(soundName); format = wave.Format; buffer = new AudioBuffer(); buffer.AudioData = wave; buffer.AudioBytes = (int)wave.Length; buffer.Flags = BufferFlags.EndOfStream; } } /// <summary> /// Manages the data for a single sound. /// </summary> public class Sound : IAsset { WaveFormat format; AudioBuffer buffer; /// <summary> /// Loads a sound from a file. /// </summary> /// <param name="soundName">The path to the sound file</param> /// <returns>Whether the sound loaded successfully</returns> public bool Load(string soundName) { if(soundName.EndsWith(".wav")) SoundLoader.LoadWAV(out format, out buffer, soundName); else return false; return true; } /// <summary> /// Plays the sound. /// </summary> public void Play() { Audio.AddInstance(new SoundInstance(format, buffer)); } /// <summary> /// Unloads the sound from memory. /// </summary> public void Unload() { buffer.Dispose(); } } /// <summary> /// Manages a single sound instance. /// </summary> public class SoundInstance { SourceVoice source; bool playing; /// <summary> /// Whether the sound is currently playing. /// </summary> public bool Playing { get { return playing; } } /// <summary> /// Starts a new instance of a sound. /// </summary> /// <param name="format">Format of the sound</param> /// <param name="buffer">Buffer holding sound data</param> internal SoundInstance(WaveFormat format, AudioBuffer buffer) { source = new SourceVoice(Audio.Device, format); source.BufferEnd += (s, e) => playing = false; source.Start(); source.SubmitSourceBuffer(buffer); // THIS IS WHERE THE EXCEPTION IS THROWN playing = true; } /// <summary> /// Releases memory used by the instance. /// </summary> internal void Dispose() { source.Dispose(); } } The exception occurs on line 156 when I am playing the sound: source.SubmitSourceBuffer(buffer);

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  • How to prevent Gnome desktop from crashing?

    - by nixnotwin
    I have ubuntu 10.10 32bit running on my Asus EEEPC 1005PX. I am experiencing frequent desktop crashes. When I turn on my netbook at least once in 5 times the defualt ubuntu theme disapears and the classic gnome theme appears. Many times while doing some work, the desktop crashes and the CLI gets shown, and after a few seconds the login screen appers. I am not using any widgets or dock bars, I just have a single gnome panel with default menus. The crashes also happen when using the default bundled ubuntu apps. Is there any way to avoid these crashes?

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  • WebLogic Application Server: free for developers!

    - by Bruno.Borges
    Great news! Oracle WebLogic Server is now free for developers! What does this mean for you? That you as a developer are permited to: "[...] deploy the programs only on your single developer desktop computer (of any type, including physical, virtual or remote virtual), to be used and accessed by only (1) named developer." But the most interesting part of the license change is this one: "You may continue to develop, test, prototype and demonstrate your application with the programs under this license after you have deployed the application for any internal data processing, commercial or production purposes" (Read the full license agreement here) If you want to take advantage of this licensing change and start developing Java EE applications with the #1 Application Server in the world, read now the previous post, How To Install WebLogic Zip on Linux!

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  • Unable to connect to FTP - Connection timeout after MLSD

    - by Afrosimon
    So here is my problem, I'm absolutely unable to connect to a FTP server, in circumstances I've never seen before. Here is the situation : I get a "Connection timed out" just after the MLSD command. I usually use Filezilla, under Ubuntu, but to make sure the problem isn't related to this particular client I tried a few others : gftp on ubuntu and winscp and freeftp on windows 7. All the same result. Also made sure to try with Active or Passive modes. Same result. At this point I would be inclined to think there is something wrong with my current network (furthermore, according to a coworker the FTP server is OK). But I did check with http://ftptest.net/ and I am able to get the directory listing (which I'm not able to through a FTP client). So in the end the last thing I didn't tried is to go on another network, solution which seems would work, but wouldn't be very practical in the long run. And thus I guess there's something wrong with my router... but what could it possibly be? Note : I did try to register and post this question on filezilla's board first... but I can't create an account with a gmail nor hotmail account. WTF?

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  • How do you set up PhysFS for use in a game?

    - by ThePlan
    After my recent question on GD I've been advised to use PhysFS to pack all my game data in 1 file. So I have, and the decission wasn't light, because I've tried out every library in my answers but none contained a single good tutorial whatsoever, in fact PhysFS is the poorest documented library I've ever seen. After attempting to set up PhysFS in my game I realized it's not as simple as adding the headers to the project, it appears something much more complicated, in fact after my first attempt to install PhysFS the compiler ran out of memory to display errors, it reached the critical count of 50 errors. So basically what I'm asking here is: How can I set up PhysFS on my game? I'm using Code::Blocks IDE on Windows XP SP3;

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  • Google I/O 2010 - Connect enterprise apps w/ Google Docs

    Google I/O 2010 - Connect enterprise apps w/ Google Docs Google I/O 2010 - Connecting your enterprise applications with Google Docs and Sites Enterprise 201 Eric Bidelman, Vijay Bangaru, Matthew Tonkin (Memeo Inc) Learn how your organization can harness the power of Google Docs and Sites directly from within your existing enterprise systems using our extensive APIs. Integrate with data from behind the firewall using Secure Data Connector. Upload, share, collaborate, and sync any file to Docs. Even automate the creation of project and team workspaces in a single click in Sites from within your CRM. For all I/O 2010 sessions, please go to code.google.com From: GoogleDevelopers Views: 18 0 ratings Time: 53:19 More in Science & Technology

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  • Silverlight Reporting Application Part 3.5 - Prism Background and WCF RIA [Series Intermission]

    Taking a step back before I dive into the details and full-on coding fun, I wanted to once again respond to a comment on my last post to clear up some things in regards to how I'm setting up my project and some of the choices I've made. Aka, thanks Ben. :) Prism Project Setup For starters, I'm not the ideal use case for a Prism application. In most cases where you've got a one-man team, Prism can be overkill as it is more intended for large teams who are geographically dispersed or in applications that have a larger scale than my Recruiting application in which you'll greatly benefit from modularity, delayed loading of xaps, etc. What Prism offers, though, is a manner for handling UI, commands, and events with the idea that, through a modular approach in which no parts really need to know about one another, I can update this application bit by bit as hiring needs change or requirements differ between offices without having to worry that changing something in the Jobs module will break something in, say, the Scheduling module. All that being said, here's a look at how our project breakdown for Recruit (MVVM/Prism implementation) looks: This could be a little misleading though, as each of those modules is actually another project in the overall Recruit solution. As far as what the projects actually are, that looks a bit like this: Recruiting Solution Recruit (Shell up there) - Main Silverlight Application .Web - Default .Web application to host the Silverlight app Infrastructure - Silverlight Class Library Project Modules - Silverlight Class Library Projects Infrastructure &Modules The Infrastructure project is probably something you'll see to some degree in any composite application. In this application, it is going to contain custom commands (you'll see the joy of these in a post or two down the road), events, helper classes, and any custom classes I need to share between different modules. Think of this as a handy little crossroad between any parts of your application. Modules on the other hand are the bread and butter of this application. Besides the shell, which holds the UI skeleton, and the infrastructure, which holds all those shared goodies, the modules are self-contained bundles of functionality to handle different concerns. In my scenario, I need a way to look up and edit Jobs, Applicants, and Schedule interviews, a Notification module to handle telling the user when different things are happening (i.e., loading from database), and a Menu to control interaction and moving between different views. All modules are going to follow the following pattern: The module class will inherit from IModule and handle initialization and loading the correct view into the correct region, whereas the Views and ViewModels folders will contain paired Silverlight user controls and ViewModel class backings. WCF RIA Services Since we've got all the projects in a single solution, we did not have to go the route of creating a WCR RIA Services Class Library. Every module has it's WCF RIA link back to the main .Web project, so the single Linq-2-SQL (yes, I said Linq-2-SQL, but I'll soon be switching to OpenAccess due to the new visual designer) context I'm using there works nicely with the scope of my project. If I were going for completely separating this project out and doing different, dynamically loaded elements, I'd probably go for the separate class library. Hope that clears that up. In the future though, I will be using that in a project that I've got in the "when I've got enough time to work on this" pipeline, so we'll get into that eventually- and hopefully when WCF RIA is in full release! Why Not use Silverlight Navigation/Business Template? The short answer- I'm a creature of habit, and having used Silverlight for a few years now, I'm used to doing lots of things manually. :) Plus, starting with a blank slate of a project I'm able to set up things exactly as I want them to be. In this case, rather than the navigation frame we would see in one of the templates, the MainRegion/ContentControl is working as our main navigation window. In many cases I will use theSilverlight navigation template to start things off, however in this case I did not need those features so I opted out of using that. Next time when I actually hit post #4, we're going to get into the modules and starting to get functionality into this application. Next week is also release week for the Q1 2010 release, so be sure to check out our annualWebinar Week (I might be biased, but Wednesday is my favorite out of the group). Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • What are good words for defining multiples?

    - by Scott Langham
    In databases you might take about one-to-many. This means there's one thing that maps to zero or more others. In this kind of style I'm looking for words that define min/max amounts of things. So far, I have: min max one 1 1 many 0 infinite optional 0 1 ??? 1 infinite Is there a single word that fits '???' to mean more than one? Do you have better alternatives for 'optional'? I'm wondering if there are any conventional names for those concepts?

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  • How do I implement Unreal-like object serialization?

    - by MrWiggels
    Recently, I've been working on the core of my engine, and as I'm moving forward I find myself developing throwaway code to read files and simple data into the engine. This got me thinking about how I should implement a file management system. After a bit of googleing I came across the Unreal Package format, and boy does it look like the perfect one. I think it's good because the way how it allows you to separate different assets into different packages and allow something like a level to reference the different packages. I was just wondering, is this possible with C#? Because the built-in serialization API in .NET does not seem to support any form of this, only reading and writing to a single file.

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  • Your software-problem-solution approach

    - by Panoy
    Hi, I am unfamiliar with many software development philosophies/approaches such as these: DDD - Domain Driven Development Design TDD - Test Driven Development BDD - Behavior Driven Development Other 3-letter acronym that ends with "development" and many more My question is, when will you get to decide to choose what kind of philosophy/approach to follow? Espceially the top 3 approach in the list: What is TDD for? Why use DDD for this problem? Mainly your answer would be a case-to-case basis or maybe that there is no single universal philosophy/approach to consider. In that case, could you just tell me what type of project/scenario and why did you use that philosophy/approach.

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  • How to build a .Net app which runs on desktop and as a Windows Service

    - by Mike
    Ok, I hope this is not too much confusing (with my poor English). I want to build a small .Net 4.0 app which monitors several other applications on a Windows Server OR on a regular Windows PC. It will have a WPF GUI with a variety of graphical controls. The app will be used in the following scenarios: If installed on a PC it should run as a “normal” single Windows desktop app If installed on a Server, it should run as a Windows Service. To use/manage the app it must have the same WPF GUI as in scenario 1 and the GUI should be run on the Server or on a remote PC At the moment I consider to write the application logic and connect it to the WPF GUI using a self-hosted WCF Data Service IN BOTH SCENARIOS. Since I’m not a pro developer I suppose it’s possible that I've missed something ;-) Will this work? Are there other/better solutions? Any answer or comment is highly appreciated.

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  • samplerCubeShadow and texture offset

    - by Irbis
    I use sampler2DShadow when accessing a single shadow map. I create PCF in this way: result += textureProjOffset(ShadowSampler, ShadowCoord, ivec2(-1,-1)); result += textureProjOffset(ShadowSampler, ShadowCoord, ivec2(-1,1)); result += textureProjOffset(ShadowSampler, ShadowCoord, ivec2(1,1)); result += textureProjOffset(ShadowSampler, ShadowCoord, ivec2(1,-1)); result = result * 0.25; For a cube map I use samplerCubeShadow: result = texture(ShadowCubeSampler, vec4(normalize(position), depth)); How to adopt above PCF when accessing a cube map ?

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  • Running a compiled Java program

    - by Roshan George
    I have a question on a compiled Java program that I have written. I have a Java file that has three classes defined within it. When I compiled the program I got a total of four classes. How do I make this into a form where I can run my application just by clicking an icon or something, or by issuing just a single command. For example, if I make it as an exe file, it could run only on Windows, how do I make it into a form compatible with all Oses. And hoe?

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  • How would you represent an object that can be of multiple types, when storing it as a document in MongoDB?

    - by blueberryfields
    Somewhat related to this question, say that I have an object category which, depending on which type of object I have, has different restrictions on what it contains. (if you can reword the previous sentence to make more sense I'd appreciate it) For example var SomeSchema = new Schema({ _id: ObjectID, [... large number of common fields ...] type: //Restricted somehow to members of a fixed array data: //depending on type, this might be restricted - sometimes an integer, sometimes array, etc... }); What's the idiosyncratic method for defining this type of schema? Is it appropriate to define a single schema, and handle the types inside of it's members, or am I better off with separate schema for each type?

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  • Breaking 1NF to model subset constraints. Does this sound sane?

    - by Chris Travers
    My first question here. Appologize if it is in the wrong forum but this seems pretty conceptual. I am looking at doing something that goes against conventional wisdom and want to get some feedback as to whether this is totally insane or will result in problems, so critique away! I am on PostgreSQL 9.1 but may be moving to 9.2 for this part of this project. To re-iterate: Does it seem sane to break 1NF in this way? I am not looking for debugging code so much as where people see problems that this might lead. The Problem In double entry accounting, financial transactions are journal entries with an arbitrary number of lines. Each line has either a left value (debit) or a right value (credit) which can be modelled as a single value with negatives as debits and positives as credits or vice versa. The sum of all debits and credits must equal zero (so if we go with a single amount field, sum(amount) must equal zero for each financial journal entry). SQL-based databases, pretty much required for this sort of work, have no way to express this sort of constraint natively and so any approach to enforcing it in the database seems rather complex. The Write Model The journal entries are append only. There is a possibility we will add a delete model but it will be subject to a different set of restrictions and so is not applicable here. If and when we allow deletes, we will probably do them using a simple ON DELETE CASCADE designation on the foreign key, and require that deletes go through a dedicated stored procedure which can enforce the other constraints. So inserts and selects have to be accommodated but updates and deletes do not for this task. My Proposed Solution My proposed solution is to break first normal form and model constraints on arrays of tuples, with a trigger that breaks the rows out into another table. CREATE TABLE journal_line ( entry_id bigserial primary key, account_id int not null references account(id), journal_entry_id bigint not null, -- adding references later amount numeric not null ); I would then add "table methods" to extract debits and credits for reporting purposes: CREATE OR REPLACE FUNCTION debits(journal_line) RETURNS numeric LANGUAGE sql IMMUTABLE AS $$ SELECT CASE WHEN $1.amount < 0 THEN $1.amount * -1 ELSE NULL END; $$; CREATE OR REPLACE FUNCTION credits(journal_line) RETURNS numeric LANGUAGE sql IMMUTABLE AS $$ SELECT CASE WHEN $1.amount > 0 THEN $1.amount ELSE NULL END; $$; Then the journal entry table (simplified for this example): CREATE TABLE journal_entry ( entry_id bigserial primary key, -- no natural keys :-( journal_id int not null references journal(id), date_posted date not null, reference text not null, description text not null, journal_lines journal_line[] not null ); Then a table method and and check constraints: CREATE OR REPLACE FUNCTION running_total(journal_entry) returns numeric language sql immutable as $$ SELECT sum(amount) FROM unnest($1.journal_lines); $$; ALTER TABLE journal_entry ADD CONSTRAINT CHECK (((journal_entry.running_total) = 0)); ALTER TABLE journal_line ADD FOREIGN KEY journal_entry_id REFERENCES journal_entry(entry_id); And finally we'd have a breakout trigger: CREATE OR REPLACE FUNCTION je_breakout() RETURNS TRIGGER LANGUAGE PLPGSQL AS $$ BEGIN IF TG_OP = 'INSERT' THEN INSERT INTO journal_line (journal_entry_id, account_id, amount) SELECT NEW.id, account_id, amount FROM unnest(NEW.journal_lines); RETURN NEW; ELSE RAISE EXCEPTION 'Operation Not Allowed'; END IF; END; $$; And finally CREATE TRIGGER AFTER INSERT OR UPDATE OR DELETE ON journal_entry FOR EACH ROW EXECUTE_PROCEDURE je_breaout(); Of course the example above is simplified. There will be a status table that will track approval status allowing for separation of duties, etc. However the goal here is to prevent unbalanced transactions. Any feedback? Does this sound entirely insane? Standard Solutions? In getting to this point I have to say I have looked at four different current ERP solutions to this problems: Represent every line item as a debit and a credit against different accounts. Use of foreign keys against the line item table to enforce an eventual running total of 0 Use of constraint triggers in PostgreSQL Forcing all validation here solely through the app logic. My concerns are that #1 is pretty limiting and very hard to audit internally. It's not programmer transparent and so it strikes me as being difficult to work with in the future. The second strikes me as being very complex and required a series of contraints and foreign keys against self to make work, and therefore it strikes me as complex, hard to sort out at least in my mind, and thus hard to work with. The fourth could be done as we force all access through stored procedures anyway and this is the most common solution (have the app total things up and throw an error otherwise). However, I think proof that a constraint is followed is superior to test cases, and so the question becomes whether this in fact generates insert anomilies rather than solving them. If this is a solved problem it isn't the case that everyone agrees on the solution....

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  • Blender 2.63a window position unstable with dual monitor extended desktop

    - by Steve Smith
    I have two 1920 x 1200 HP monitors and running Ubuntu 12.10. If I set them up as an extended desktop, (both 1280 x 1024 positioned for 2048 x 1280, all my applications work fine EXCEPT Blender (even Inkscape). Blender works great on a single monitor but always defaults to a window size that uses all available real estate and it can't do that with 2048 x 1280. It launches, but jumps all over the screen. Does any know a way to start Blender in a fixed size window so it would run in just one monitor?

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