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  • Cocos2d and Body with few collision shapes using chipmunk

    - by Eimantas
    I'm using Cocos2d (0.99.5) with chipmunk physics engine. Currently I'm trying to place a body into space which is combined from few circle shapes. Let's say I have a corresponding sprite image with displays atom (nucleus + 3 electrons around it. Something like this without orbit lines). In it's simplest form - only one circle shape at the center should be enough which would detect collisions from other objects with nucleus. Now I'd like to add other circle shapes for each electron. How can I do that? Now when I add those shapes to the body and add the body into chipmunk space - the shapes (together with the body/sprite) start flickering and spinning with no recognizable pattern (or reason for that matter).

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  • Thoughts about MVC

    - by ayyash
    so i figured this one out, as a newcomer to the web development scene from the telecom biz, where we dealt with low level hardware API's, and a C++ fanboy, i tend to be bothered by automagical code, yes i appreciate the effort that went into it, and i certainly appreciate the luxury it provides to get more things done, but i just don't get it. so i decided to change that, and start investigating the new MVC based web apps, and at first it was like hitting a brick wall, i knew MVC from MFC days, so i'm familiar with the pattern, but i just couldn't get my head around the web version of it, till i came to realize the routing, is actually a separate feature to be inspected, much like understanding how LINQ works by better understanding anonymous objects. and so this article serve as an introduction to the following blogs where i share my views of how asp.net routing works, and then leverage that to the MVC level, and play around that field for a bit. as with most of my shared knowladge that may seem trivial to some, but i guess a newcomer's point of view can be useful for some folks out there.

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  • Distinct Count of Customers in a SCD Type 2 in #DAX

    - by Marco Russo (SQLBI)
    If you have a Slowly Changing Dimension (SCD) Type 2 for your customer and you want to calculate the number of distinct customers that bought a product, you cannot use the simple formula: Customers := DISTINCTCOUNT( FactTable[Customer Id] ) ) because it would return the number of distinct versions of customers. What you really want to do is to calculate the number of distinct application keys of the customers, that could be a lower number than the number you’ve got with the previous formula. Assuming that a Customer Code column in the Customers dimension contains the application key, you should use the following DAX formula: Customers := COUNTROWS( SUMMARIZE( FactTable, Customers[Customer Code] ) ) Be careful: only the version above is really fast, because it is solved by xVelocity (formerly known as VertiPaq) engine. Other formulas involving nested calculations might be more complex and move computation to the formula engine, resulting in slower query. This is absolutely an interesting pattern and I have to say it’s a killer feature. Try to do the same in Multidimensional…

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  • Java web UI framework like ASP.NET MVC?

    - by Ethel Evans
    I'm doing some web apps for personal projects that might be shared out with my friends. I'm trying to use skills that will help me at work, but don't have $$ to spend on Visual Studio right now and don't want to try to cobble something together with Express Editions. Since I've been sort of wanting to bring my Java skills up to date and the main skills I want to work on are design and architecture skills, this isn't a big deal - except that I have no idea how to track down the right UI framework. I know I want something based on MVC, to get more practice with frameworks for that design pattern (we're using ASP .NET MVC2 at work). The UIs that I'll be making will be pretty simple - data entry, buttons, text, images. They will need AJAX. Any thoughts about which frameworks to look at? I'll be watching the comments, if anyone wants additional clarification on what I'm looking for.

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  • Simpler alternative to AngelScript

    - by Vee
    I want to give players the ability to create and share bullet patterns for a shoot'em up. The pattern scripts should have all the common programming stuff like loops, if/else, variables, and so on. But in the end, I just want them to call a "spawn bullet at X, Y with Z angle and A speed" in the C++ game. To spawn a circle of bullets, the user should only have to write a script with a for loop that goes from 0 to 360 and calls the spawn bullet function on every iteration. I tried integrating AngelScript, but I am getting nowhere - it looks way to complex for a simple task like this one. Is there an easy to integrate library that can solve my problem? Thanks.

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  • How to play many sounds at once in OpenAL

    - by Krom
    Hello, I'm developing an RTS game and I would like to add sounds to it. My choice has landed on OpenAL. I have plenty of units which from time to time make sounds: fSound.Play(sfx_shoot, location). Sounds often repeat, e.g. when squad of archers shoots arrows, but they are not synced with each other. My questions are: What is the common design pattern to play multiple sounds in OpenAL, when some of them are duplicate? What are the hardware limitations on sounds count and tricks to overcome them?

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  • What options are there for integrating with payment gateways?

    - by Rowland Shaw
    It seems that there are only two types of payment gateway service out there at the moment; Either that the entire cart logic is handled offsite (with something like Paypal's Standard option) or the other option being that you need to go through the certification for handling credit card numbers and doing pretty much everything yourself. Ideally, for the project I'm working on, I'm after a bit of middle ground such that I can handle the cart on-site, and only pass over to a payment gateway (with an order amount, billing & delivery details, and order ref) for them to handle the card details, before passing back. I'm sure that I've used e-commerce sites using this pattern before, but I cannot find any payment providers out there that offer this sort of option, so are there any? The only over requirement we have at present is that it must accept orders in Sterling.

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  • Standard -server to server- and -browser to server- authentication method

    - by jeruki
    I have server with some resources; until now all these resources were requested through a browser by a human user, and the authentication was made with an username/password method, that generates a cookie with a token (to have the session open for some time). Right now the system requires that other servers make GET requests to this resource server but they have to authenticate to get them. We have been using a list of authorized IPs but having two authentication methods makes the code more complex. My questions are: Is there any standard method or pattern to authenticate human users and servers using the same code? If there is not, are the methods I'm using now the right ones or is there a better / more standard way to accomplish what I need? Thanks in advance for any suggestion.

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  • Is it OK to have a team with same abilities but different skill levels?

    - by A. Karimi
    I believe that in an ideal team, members should have different but complementary abilities. But is that true about software development teams? As an example we are a small team of 5. We almost have the same abilities and interests but with different levels of skills. Regarding such situation I think we don't cover our teammates' weaknesses. Is there any pattern to follow to manage and improve such team? Should I setup a team with different abilities and interests to maximize the performance and productivity? -- EDIT -- Our current team has a specific lifetime. We work together in a per-project manner. In another word we may change the team arrangement for each project depending on the project and developers situation. Actually we've provided a sort of floating situation. In short, we are a network of developers rather than a fixed-size development team.

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  • Alternative to "inheritance v composition??"

    - by Frank
    I have colleagues at work who claim that "Inheritance is an anti-pattern" and want to use composition systematically instead, except in (rare, according to them) cases where inheritance is really the best way to go. I want to suggest an alternative where we continue using inheritance, but it is strictly forbidden (enforced by code reviews) to use anything but public members of base classes in derived classes. For a case where we don't need to swap components of a class at runtime (static inheritance), would that be equivalent enough to composition? Or am I forgetting some other important aspect of composition?

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  • Design Patterns and their most common uses for them [closed]

    - by cable729
    Possible Duplicate: What are some programming design patterns that are useful in game development? As I'm returning to game dev, I've realized that I've lost a lot of the knowledge I had before. So now I'm looking at design patterns that I can use for my next project. One design pattern that I've seen a lot is the 'composition method,' which uses actors and components. Is that the right name for it? I'd like to look more at this and see what the advantages/pitfalls are. So what design patterns are out there, and what are the advantages/disadvantages to them?

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  • Oracle Speakers at QCon New York, June 18-20, 2012

    - by Bob Rhubart
    If you're attending the QCon Conference in NYC, June 18-20, 2012, you'll find several presenters from Oracle among the impressive roster of speakers. Among those sharing their expertise at the New York event: Arun Gupta: Java EE & GlassFish Guy, Oracle Presentation: Java EE 7 and HTML5: Developing for the Cloud Brian Oliver: Global Solutions Architect, Oracle Presentation: The Live Object Pattern Cameron Purdy: Vice President of Development, Oracle Presentation: How the 10 key lessons from Java and C++ history inform the Cloud Charlie Hunt: JVM Performance Lead Engineer, Oracle Presentation: Extreme Performance with Java Registration for the event is still open. According to the website, registering before June 1 will save you $300. If you snooze, you lose.

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  • Why can't I get a working session with vnc4server

    - by ysap
    We have a couple of (identical) Ubuntu 11.10 machines, configured with gnome-classic, which we use as remote servers, and let our clients log into personal user accounts we create for them using vnc4server. We configured all the machines in the same way, following a short manual we compiled, describing how to download, install and prepare a few tools and our software. The connection usually works fine, but today I set up a fresh machine, and experienced problems. After installing vnc4server, I ran vncpasswd and copied the following startup file to ~/.vnc/xstartup: #!/bin/sh unset SESSION_MANAGER unset DBUS_SESSION_BUS_ADDRESS gnome-session --session=gnome-classic & [ -x /etc/vnc/xstartup ] && exec /etc/vnc/xstartup [ -r $HOME/.Xresources ] && xrdb $HOME/.Xresources xsetroot -solid grey vncconfig -iconic & Then, I started vnc4server and used two viewers (the Ubuntu Remote Desktop Viewer and Windows RealVNC Client) in two other machines, but instead of getting my desktop, I see an empty window with a grey-ish background pattern like this: and the cursor is a bold X. What is wrong with the setup and why don't I get a remote session as expected?

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  • Will these type of 403 errors affect my ranking?

    - by Gkhan14
    Let's say I have a directory that has a 403 forbidden error for all of the content in it, however a few of the images in the subdirectoies of the main diretory do NOT have a 403 forbidden error. Will this fact affect my ranking? For example: test.com/system/ (HAS 403 ERROR FOR ALL FILES) - test.com/system/pie/ (HAS 403 ERROR FOR ALL FILES) - test.com/system/pie/image.png (DOES NOT HAVE A 403 ERROR, AND THIS IMAGE IS EMBEDED ON A PAGE ON test.com e.g(test.com/pie/)) This sort of pattern repeats for about 10 different images. This directory is like a secret "system", however all of the content on the main site (test.com) is still accessible to everyone from the public.

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  • Sharing Authentication Across Subdomains using cookies

    - by Jordan Reiter
    I know that in general cookies themselves are not considered robust enough to store authentication information. What I am wondering is if there is an existing design pattern or framework for sharing authentication across subdomains without having to use something more complex like OpenID. Ideally, the process would be that the user visits abc.example.org, logs in, and continues on to xyz.example.org where they are automatically recognized (ideally, the reverse should also be possible -- a login via xyz means automatic login at abc). The snag is that abc.example.org and xyz.example.org are both on different servers and different web application frameworks, although they can both use a shared database. The web application platforms include PHP, ColdFusion, and Python (Django), although I'm also interested in this from a more general perspective (i.e. language agnostic).

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  • How to implement soft edge areas with particles

    - by OpherV
    My game is created using Phaser, but the question itself is engine-agnostic. In my game I have several environments, essentially polygonal areas that player characters can move into and be affected by. For example ice, fire, poison etc' The graphic element of these areas is the color filled polygon area itself, and particles of the suitable type (in this example ice shards). This is how I'm currently implementing this - with a polygon mask covering a tilesprite with the particle pattern: The hard edge looks bad. I'd like to improve by doing two things: 1. Making the polygon fill area to have a soft edge, and blend into the background. 2. Have some of the shards go out of the polygon area, so that they are not cut in the middle and the area doesn't have a straight line for example (mockup): I think 1 can be achieved with blurring the polygon, but I'm not sure how to go about with 2. How would you go about implementing this?

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  • Drawing different per-pixel data on the screen

    - by Amir Eldor
    I want to draw different per-pixel data on the screen, where each pixel has a specific value according to my needs. An example may be a random noise pattern where each pixel is randomly generated. I'm not sure what is the correct and fastest way to do this. Locking a texture/surface and manipulating the raw pixel data? How is this done in modern graphics programming? I'm currently trying to do this in Pygame but realized I will face the same problem if I go for C/SDL or OpenGL/DirectX.

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  • Is "watermarking" code with random trailing whitespace a good way to detect plagiarism?

    - by paperjam
    Consider this: int f(int x) { return 2 * x * x; } and this int squareAndDouble(int y) { return 2*y*y; } If you found these in independent bodies of code, you might give the two programmers the benefit of the doubt and assume they came up with more-or-less the same function independently. But look at the whitespace at the end of each line of code. Same pattern in both. Surely evidence of copying. On a larger piece of code, correlation of random whitespace at line ends would be irrefutable evidence of a shared origin. Now aside from the obvious weaknesses: e.g. visible or obvious in some editors, easily removed, I was wondering if it was worth deploying something like this in my open source project. My industry has a history of companies ripping off open source projects.

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  • Do delegates defy OOP

    - by Dave Rook
    I'm trying to understand OOP so I can write better OOP code and one thing which keeps coming up is this concept of a delegate (using .NET). I could have an object, which is totally self contained (encapsulated); it knows nothing of the outside world... but then I attach a delegate to it. In my head, this is still quite well separated as the delegate only knows what to reference, but this by itself means it has to know about something else outside it's world! That a method exists within another class! Have I got myself it total muddle here, or is this a grey area, or is this actually down to interpretation (and if so, sorry as that will be off topic I'm sure). My question is, do delegates defy/muddy the OOP pattern?

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  • Access Control Management Tool ACM.exe

    - by kaleidoscope
    The Access Control Management Tool (Acm.exe) is a command-line tool you can use to perform management operations (CREATE, UPDATE, GET, GET ALL, and DELETE) on the AppFabric Access Control entities (scopes, issuers, token policies, and rules). Basic Syntax The command line for Acm.exe follows the basic pattern of verb-noun. For example: acm.exe <command> <resource> [-option:<option value>] This tool will automatically generate random keys, which helps ensure that they can't easily be guessed by an attacker. Note that ACM.EXE is a thin wrapper around a REST Web Service (the AC management service). That helps to remember the commands it accepts, which are the typical resource management commands for a REST service: · Get(All) · Create · Update · Delete ACM.EXE.config file can be used to configure Host, Service and the Management key for a Service Namespace. Geeta, G

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  • C# WebForms and Ninject

    - by ipohfly
    I'm re-working on the design of an existing application which is build using WebForms. Currently the plan is to work it into a MVP pattern application while using Ninject as the IoC container. The reason for Ninject to be there is that the boss had wanted a certain flexibility within the system so that we can build in different flavor of business logic in the model and let the programmer to choose which to use based on the client request, either via XML configuration or database setting. I know that Ninject have no need for XML configuration, however I'm confused on how it can help to dynamically inject the dependency into the system? Imagine I have a interface IMember and I need to bind this interface to the class decided by a xml or database configuration at the launch of the application, how can I achieve that?

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  • Computer Arithmetic - Binary for Decimal Numbers

    - by MarkPearl
    This may be of use to someone else doing this course… The Problem In the section on Computer Arithmetic it gives an example of converting -7.6875 to IEEE floating point format. I understand all the steps except for the first one, where it does the following... 7.6875 (base 10) = 111.1011 (base 2) I don't understand the conversion - I realize that 111 (base 2) = 7 (base 10), but how does the .6875 part relate to the .1011? Or am I totally off track with this? The Solution The fractional part of the decimal to binary conversion is done as follows: 0.6875 x 2 = 1.375 = 0.375 + 1 (Keep the 1 separate) 0.375 x 2   = 0.75   = 0.75    + 0 0.75 x 2    = 1.5      = 0.5      + 1 0.5 x 2     = 1.0       = 0.0       + 1 The bit pattern of 0s and 1s on the right-hand side gives you the fractional part. So 0.6875 (base 10) = .1011 (Base 2) See also Stallings, chapter 19.

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  • Lean/Kanban *Inside* Software (i.e. WIP-Limits, Reducing Queues and Pull as Programming Techniques)

    - by Christoph
    Thinking about Kanban, I realized that the queuing-theory behind the SW-development-methodology obviously also applies to concurrent software. Now I'm looking for whether this kind of thinking is explicitly applied in some area. A simple example: We usually want to limit the number of threads to avoid cache-thrashing (WIP-Limits). In the paper about the disruptor pattern[1], one statement that I found interesting was that producer/consumers are rarely balanced so when using queues, either consumers wait (queues are empty), or producers produce more than is consumed, resulting in either a full capacity-constrained queue or an unconstrained one blowing up and eating away memory. Both, in lean-speak, is waste, and increases lead-time. Does anybody have examples of WIP-Limits, reducing/eliminating queues, pull or single piece flow being applied in programming? http://disruptor.googlecode.com/files/Disruptor-1.0.pdf

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  • New Procurement Report for Transportation Sourcing

    - by John Murphy
    Welcome to our fourth annual transportation procurement benchmark report. American Shipper, in partnership with the Council of Supply Chain Management Professionals (CSCMP) and the Retail Industry Leaders Association (RILA), surveyed roughly 275 transportation buyers and sellers on procurement practices, processes, technologies and results. Some key findings: • Manual, spreadsheet-based procurement processes remain the most prevalent among transportation buyers, with 42 percent of the total • Another 25 percent of respondents use a hybrid platform, which presumably means these buyers are using spreadsheets for at least one mode and/or geography • Only 23 percent of buyers are using a completely systems-based approach of some kind • Shippers were in a holding pattern with regards to investment in procurement systems the past year • Roughly three-quarters of survey respondents report that transportation spend has increased in 2012, although the pace has declined slightly from last year’s increases • Nearly every survey respondent purchases multiple modes of transportation • The number of respondents with plans to address technology to support the procurement process has increased in 2012. About one quarter of respondents who do not have a system report they have a budget for this investment in the next two years.

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  • yield – Just yet another sexy c# keyword?

    - by George Mamaladze
    yield (see NSDN c# reference) operator came I guess with .NET 2.0 and I my feeling is that it’s not as wide used as it could (or should) be.   I am not going to talk here about necessarity and advantages of using iterator pattern when accessing custom sequences (just google it).   Let’s look at it from the clean code point of view. Let's see if it really helps us to keep our code understandable, reusable and testable.   Let’s say we want to iterate a tree and do something with it’s nodes, for instance calculate a sum of their values. So the most elegant way would be to build a recursive method performing a classic depth traversal returning the sum.           private int CalculateTreeSum(Node top)         {             int sumOfChildNodes = 0;             foreach (Node childNode in top.ChildNodes)             {                 sumOfChildNodes += CalculateTreeSum(childNode);             }             return top.Value + sumOfChildNodes;         }     “Do One Thing” Nevertheless it violates one of the most important rules “Do One Thing”. Our  method CalculateTreeSum does two things at the same time. It travels inside the tree and performs some computation – in this case calculates sum. Doing two things in one method is definitely a bad thing because of several reasons: ·          Understandability: Readability / refactoring ·          Reuseability: when overriding - no chance to override computation without copying iteration code and vice versa. ·          Testability: you are not able to test computation without constructing the tree and you are not able to test correctness of tree iteration.   I want to spend some more words on this last issue. How do you test the method CalculateTreeSum when it contains two in one: computation & iteration? The only chance is to construct a test tree and assert the result of the method call, in our case the sum against our expectation. And if the test fails you do not know wether was the computation algorithm wrong or was that the iteration? At the end to top it all off I tell you: according to Murphy’s Law the iteration will have a bug as well as the calculation. Both bugs in a combination will cause the sum to be accidentally exactly the same you expect and the test will PASS. J   Ok let’s use yield! That’s why it is generally a very good idea not to mix but isolate “things”. Ok let’s use yield!           private int CalculateTreeSumClean(Node top)         {             IEnumerable<Node> treeNodes = GetTreeNodes(top);             return CalculateSum(treeNodes);         }             private int CalculateSum(IEnumerable<Node> nodes)         {             int sumOfNodes = 0;             foreach (Node node in nodes)             {                 sumOfNodes += node.Value;             }             return sumOfNodes;         }           private IEnumerable<Node> GetTreeNodes(Node top)         {             yield return top;             foreach (Node childNode in top.ChildNodes)             {                 foreach (Node currentNode in GetTreeNodes(childNode))                 {                     yield return currentNode;                 }             }         }   Two methods does not know anything about each other. One contains calculation logic another jut the iteration logic. You can relpace the tree iteration algorithm from depth traversal to breath trevaersal or use stack or visitor pattern instead of recursion. This will not influence your calculation logic. And vice versa you can relace the sum with product or do whatever you want with node values, the calculateion algorithm is not aware of beeng working on some tree or graph.  How about not using yield? Now let’s ask the question – what if we do not have yield operator? The brief look at the generated code gives us an answer. The compiler generates a 150 lines long class to implement the iteration logic.       [CompilerGenerated]     private sealed class <GetTreeNodes>d__0 : IEnumerable<Node>, IEnumerable, IEnumerator<Node>, IEnumerator, IDisposable     {         ...        150 Lines of generated code        ...     }   Often we compromise code readability, cleanness, testability, etc. – to reduce number of classes, code lines, keystrokes and mouse clicks. This is the human nature - we are lazy. Knowing and using such a sexy construct like yield, allows us to be lazy, write very few lines of code and at the same time stay clean and do one thing in a method. That's why I generally welcome using staff like that.   Note: The above used recursive depth traversal algorithm is possibly the compact one but not the best one from the performance and memory utilization point of view. It was taken to emphasize on other primary aspects of this post.

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