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• Azure Mobile Services: lessons learned

  - by svdoever

  When I first started using Azure Mobile Services I thought of it as a nice way to: authenticate my users - login using Twitter, Google, Facebook, Windows Live create tables, and use the client code to create the columns in the table because that is not possible in the Azure Mobile Services UI run some Javascript code on the table crud actions (Insert, Update, Delete, Read) schedule a Javascript to run any 15 or more minutes I had no idea of the magic that was happening inside… where is the data stored? Is it a kind of big table, are relationships between tables possible? those Javascripts on the table crud actions, is that interpreted, what is that exactly? After working for some time with Azure Mobile Services I became a lot wiser: Those tables are just normal tables in an Azure SQL Server 2012 Creating the table columns through client code sucks, at least from my Javascript code, because the columns are deducted from the sent JSON data, and a datetime field is sent as string in JSON, so a string type column is created instead of a datetime column You can connect with SQL Management Studio to the Azure SQL Server, and although you can’t manage your columns through the SQL Management Studio UI, it is possible to just run SQL scripts to drop and create tables and indices When you create a table through SQL script, add the table with the same name in the Azure Mobile Services UI to hook it up and be able to access the table through the provided abstraction layer You can also go to the SQL Database through the Azure Mobile Services UI, and from there get in a web based SQL management studio where you can create columns and manage your data The table crud scripts and the scheduler scripts are full blown node.js scripts, introducing a lot of power with great performance The web based script editor is really powerful, I do most of my editing currently in the editor which has syntax highlighting and code completing. While editing the code JsHint is used for script validation. The documentation on Azure Mobile Services is… suboptimal. It is such a pity that there is no way to comment on it so the community could fill in the missing holes, like which node modules are already loaded, and which modules are available on Azure Mobile Services. Soon I was hacking away on Azure Mobile Services, creating my own database tables through script, and abusing the read script of an empty table named query to implement my own set of “services”. The latest updates to Azure Mobile Services described in the following posts added some great new features like creating web API’s, use shared code from your scripts, command line tools for managing Azure Mobile Services (upload and download scripts for example), support for node modules and git support: http://weblogs.asp.net/scottgu/archive/2013/06/14/windows-azure-major-updates-for-mobile-backend-development.aspx http://blogs.msdn.com/b/carlosfigueira/archive/2013/06/14/custom-apis-in-azure-mobile-services.aspx http://blogs.msdn.com/b/carlosfigueira/archive/2013/06/19/custom-api-in-azure-mobile-services-client-sdks.aspx In the mean time I rewrote all my “service-like” table scripts to API scripts, which works like a breeze. Bad thing with the current state of Azure Mobile Services is that the git support is not working if you are a co-administrator of your Azure subscription, and not and administrator (as in my case). Another bad thing is that Cross Origin Request Sharing (CORS) is not supported for the API yet, so no go yet from the browser client for API’s, which is my case. See http://social.msdn.microsoft.com/Forums/windowsazure/en-US/2b79c5ea-d187-4c2b-823a-3f3e0559829d/known-limitations-for-source-control-and-custom-api-features for more on these and other limitations. In his talk at Build 2013 Josh Twist showed that there is a work-around for accessing shared script code from the table scripts as well (another limitation mentioned in the post above). I could not find that code in the Votabl2 code example from the presentation at https://github.com/joshtwist/votabl2, but we can grab it from the presentation when it comes online on Channel9. By the way: you can always express your needs and ideas at http://mobileservices.uservoice.com, that’s the place they are listening to (I hope!).

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• Node.js Lockstep Multiplayer Architecture

  - by Wakaka

  Background I'm using the lockstep model for a multiplayer Node.js/Socket.IO game in a client-server architecture. User input (mouse or keypress) is parsed into commands like 'attack' and 'move' on the client, which are sent to the server and scheduled to be executed on a certain tick. This is in contrast to sending state data to clients, which I don't wish to use due to bandwidth issues. Each tick, the server will send the list of commands on that tick (possibly empty) to each client. The server and all clients will then process the commands and simulate that tick in exactly the same way. With Node.js this is actually quite simple due to possibility of code sharing between server and client. I'll just put the deterministic simulator in the /shared folder which can be run by both server and client. The server simulation is required so that there is an authoritative version of the simulation which clients cannot alter. Problem Now, the game has many entity classes, like Unit, Item, Tree etc. Entities are created in the simulator. However, for each class, it has some methods that are shared and some that are client-specific. For instance, the Unit class has addHp method which is shared. It also has methods like getSprite (gets the image of the entity), isVisible (checks if unit can be seen by the client), onDeathInClient (does a bunch of stuff when it dies only on the client like adding announcements) and isMyUnit (quick function to check if the client owns the unit). Up till now, I have been piling all the client functions into the shared Unit class, and adding a this.game.isServer() check when necessary. For instance, when the unit dies, it will call if (!this.game.isServer()) { this.onDeathInClient(); }. This approach has worked pretty fine so far, in terms of functionality. But as the codebase grew bigger, this style of coding seems a little strange. Firstly, the client code is clearly not shared, and yet is placed under the /shared folder. Secondly, client-specific variables for each entity are also instantiated on the server entity (like unit.sprite) and can run into problems when the server cannot instantiate the variable (it doesn't have Image class like on browsers). So my question is, is there a better way to organize the client code, or is this a common way of doing things for lockstep multiplayer games? I can think of a possible workaround, but it does have its own problems. Possible workaround (with problems) I could use Javascript mixins that are only added when in a browser. Thus, in the /shared/unit.js file in the /shared folder, I would have this code at the end: if (typeof exports !== 'undefined') module.exports = Unit; else mixin(Unit, LocalUnit); Then I would have /client/localunit.js store an object LocalUnit of client-side methods for Unit. Now, I already have a publish-subscribe system in place for events in the simulator. To remove the this.game.isServer() checks, I could publish entity-specific events whenever I want the client to do something. For instance, I would do this.publish('Death') in /shared/unit.js and do this.subscribe('Death', this.onDeathInClient) in /client/localunit.js. But this would make the simulator's event listeners list on the server and the client different. Now if I want to clear all subscribed events only from the shared simulator, I can't. Of course, it is possible to create two event subscription systems - one client-specific and one shared - but now the publish() method would have to do if (!this.game.isServer()) { this.publishOnClient(event); }. All in all, the workaround off the top of my head seems pretty complicated for something as simple as separating the client and shared code. Thus, I wonder if there is an established and simpler method for better code organization, hopefully specific to Node.js games.

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• Algorithm for tracking progress of controller method running in background

  - by SilentAssassin

  I am using Codeigniter framework for PHP on Windows platform. My problem is I am trying to track progress of a controller method running in background. The controller extracts data from the database(MySQL) then does some processing and then stores the results again in the database. The complete aforesaid process can be considered as a single task. A new task can be assigned while another task is running. The newly assigned task will be added in a queue. So if I can track progress of the controller, I can show status for each of these tasks. Like I can show "Pending" status for tasks in the queue, "In Progress" for tasks running and "Done" for tasks that are completed. Main Issue: Now first thing I need to find is an algorithm to track the progress of how much amount of execution the controller method has completed and that means tracking how much amount of method has completed execution. For instance, this PHP script tracks progress of array being counted. Here the current state and state after total execution are known so it is possible to track its progress. But I am not able to devise anything analogous to it in my case. Maybe what I am trying to achieve is programmtically not possible. If its not possible then suggest me a workaround or a completely new approach. If some details are pending you can mention them. Sorry for my ignorance this is my first post here. I welcome you to point out my mistakes. EDIT: Database outline: The URL(s) and keyword(s) are first entered by user which are stored in a database table called link_master and keyword_master respectively. Then keywords are extracted from all the links present in this table and compared with keywords entered by user and their frequency is calculated which is the final result. And the results are stored in another table called link_result. Now sub-links are extracted from the domain links and stored in a table called sub_link_master. Now again the keywords are extracted from these sub-links and the corresponding results are stored in a table called sub_link_result. The number of records cannot be defined beforehand as the number of links on any web page can be different. Only the cardinality of *link_result* table can be known which will be equal to multiplication of number of keyword(s) and URL(s) . I insert multiple records at a time using this resource. Controller outline: The controller extracts keywords from a web page and also extracts keywords from all the links present on that page. There is a method called crawlLink. I used Rolling Curl to extract keywords and web page content. It has callback function which I used for extracting keywords alongwith generating results and extracting valid sub-links. There is a insertResult method which stores results for links and sub-links in the respective tables. Yes, the processing depends on the number of records. The more the number of records, the more time it takes to execute: Consider this scenario: Number of Domain Links = 1 Number of Keywords = 3 Number of Domain Links Result generated = 3 (3 x 1 as described in the question) Number of Sub Links generated = 41 Number of Sub Links Result = 117 (41 x 3 = 123 but some links are not valid or searchable) Approximate time taken for above process to complete = 55 seconds. The above result is for a single link. I want to track the progress of the above results getting stored in database. When all results are stored, the task is complete. If results are getting stored, the task is In Progress. I am not clear how can I track this progress.

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• AI to move custom-shaped spaceships (shape affecting movement behaviour)

  - by kaoD

  I'm designing a networked turn based 3D-6DOF space fleet combat strategy game which relies heavily on ship customization. Let me explain the game a bit, since you need to know a bit about it to set the question. What I aim for is the ability to create your own fleet of ships with custom shapes and attached modules (propellers, tractor beams...) which would give advantages and disadvantages to each ship, so you have lots of different fleet distributions. E.g., long ship with two propellers at the side would let the ship spin around that plane easily, bigger ships would move slowly unless you place lots of propellers at the back (therefore spending more "construction" points and energy when moving, and it will only move fast towards that direction.) I plan to balance all the game around this feature. The game would revolve around two phases: orders and combat phase. During the orders phase, you command the different ships. When all players finish the order phase, the combat phase begins and the ship orders get resolved in real-time for some time, then the action pauses and there's a new orders phase. The problem comes when I think about player input. To move a ship, you need to turn on or off different propellers if you want to steer, travel forward, brake, rotate in place... These propellers don't have to work at their whole power, so you can achieve more movement combinations with less propellers. I think this approach is a bit boring. The player doesn't want to fiddle with motors or anything, you just want to MOVE and KILL. The way I intend the player to give orders to these ships is by a destination and a rotation, and then the AI would calculate the correct propeller power to achive that movement and rotation. Propulsion doesn't have to be the same throught the entire turn calculation (after the orders have been given) so it would be cool if the ships reacted as they move, adjusting the power of the propellers for their needs dynamically, but it may be too hard to implement and it's not really needed for the game to work. In both cases, how would that AI decide which propellers to activate for the best (or at least not worst) trajectory to be achieved? I though about some approaches: Learning AI: The ship types would learn about their movement by trial and error, adjusting their behaviour with more uses, and finally becoming "smart". I don't want to get involved THAT far in AI coding, and I think it can be frustrating for the player (even if you can let it learn without playing.) Pre-calculated timestep movement: Upon ship creation, ALL possible movements are calculated for each propeller configuration and power for a given delta-time. Memory intensive, ugly, bad. Pre-calculated trajectories: The same as above but not for each delta-time but the whole trajectory, which would then be fitted as much as possible. Requires a fixed propeller configuration for the whole combat phase and is still memory intensive, ugly and bad. Continuous brute forcing: The AI continously checks ALL possible propeller configurations throughout the entire combat phase, precalculates a few time steps and decides which is the best one based on that. Con: what's good now might not be that good later, and it's too CPU intensive, ugly, and bad too. Single brute forcing: Same as above, but only brute forcing at the beginning of the simulation, so it needs constant propeller configuration throughout the entire combat phase. Coninuous angle check: This is not a full movement method, but maybe a way to discard "stupid" propeller configurations. Given the current propeller's normal vector and the final one, you can approximate the power needed for the propeller based on the angle. You must do this continuously throughout the whole combat phase. I figured this one out recently so I didn't put in too much thought. A priori, it has the "what's good now might not be that good later" drawback too, and it doesn't care about the other propellers which may act together to make a better propelling configuration. I'm really stuck here. Any ideas?

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• Approach for packing 2D shapes while minimizing total enclosing area

  - by Dennis

  Not sure on my tags for this question, but in short .... I need to solve a problem of packing industrial parts into crates while minimizing total containing area. These parts are motors, or pumps, or custom-made components, and they have quite unusual shapes. For some, it may be possible to assume that a part === rectangular cuboid, but some are not so simple, i.e. they assume a shape more of that of a hammer or letter T. With those, (assuming 2D shape), by alternating direction of top & bottom, one can pack more objects into the same space, than if all tops were in the same direction. Crude example below with letter "T"-shaped parts: ***** xxxxx ***** x ***** *** ooo * x vs * x vs * x vs * x o * x * xxxxx * x * x o xxxxx xxx Right now we are solving the problem by something like this: using CAD software, make actual models of how things fit in crate boxes make estimates of actual crate dimensions & write them into Excel file (1) is crazy amount of work and as the result we have just a limited amount of possible entries in (2), the Excel file. The good things is that programming this is relatively easy. Given a combination of products to go into crates, we do a lookup, and if entry exists in the Excel (or Database), we bring it out. If it doesn't, we say "sorry, no data!". I don't necessarily want to go full force on making up some crazy algorithm that given geometrical part description can align, rotate, and figure out best part packing into a crate, given its shape, but maybe I do.. Question Well, here is my question: assuming that I can represent my parts as 2D (to be determined how), and that some parts look like letter T, and some parts look like rectangles, which algorithm can I use to give me a good estimate on the dimensions of the encompassing area, while ensuring that the parts are packed in a minimal possible area, to minimize crating/shipping costs? Are there approximation algorithms? Seeing how this can get complex, is there an existing library I could use? My thought / Approach My naive approach would be to define a way to describe position of parts, and place the first part, compute total enclosing area & dimensions. Then place 2nd part in 0 degree orientation, repeat, place it at 180 degree orientation, repeat (for my case I don't think 90 degree rotations will be meaningful due to long lengths of parts). Proceed using brute force "tacking on" other parts to the enclosing area until all parts are processed. I may have to shift some parts a tad (see 3rd pictorial example above with letters T). This adds a layer of 2D complexity rather than 1D. I am not sure how to approach this. One idea I have is genetic algorithms, but I think those will take up too much processing power and time. I will need to look out for shape collisions, as well as adding extra padding space, since we are talking about real parts with irregularities rather than perfect imaginary blocks. I'm afraid this can get geometrically messy fairly fast, and I'd rather keep things simple, if I can. But what if the best (practical) solution is to pack things into different crate boxes rather than just one? This can get a bit more tricky. There is human element involved as well, i.e. like parts can go into same box and are thus a constraint to be considered. Some parts that are not the same are sometimes grouped together for shipping and can be considered as a common grouped item. Sometimes customers want things shipped their way, which adds human element to constraints. so there will have to be some customization.

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• Concurrent Affairs

  - by Tony Davis

  I once wrote an editorial, multi-core mania, on the conundrum of ever-increasing numbers of processor cores, but without the concurrent programming techniques to get anywhere near exploiting their performance potential. I came to the.controversial.conclusion that, while the problem loomed for all procedural languages, it was not a big issue for the vast majority of programmers. Two years later, I still think most programmers don't concern themselves overly with this issue, but I do think that's a bigger problem than I originally implied. Firstly, is the performance boost from writing code that can fully exploit all available cores worth the cost of the additional programming complexity? Right now, with quad-core processors that, at best, can make our programs four times faster, the answer is still no for many applications. But what happens in a few years, as the number of cores grows to 100 or even 1000? At this point, it becomes very hard to ignore the potential gains from exploiting concurrency. Possibly, I was optimistic to assume that, by the time we have 100-core processors, and most applications really needed to exploit them, some technology would be around to allow us to do so with relative ease. The ideal solution would be one that allows programmers to forget about the problem, in much the same way that garbage collection removed the need to worry too much about memory allocation. From all I can find on the topic, though, there is only a remote likelihood that we'll ever have a compiler that takes a program written in a single-threaded style and "auto-magically" converts it into an efficient, correct, multi-threaded program. At the same time, it seems clear that what is currently the most common solution, multi-threaded programming with shared memory, is unsustainable. As soon as a piece of state can be changed by a different thread of execution, the potential number of execution paths through your program grows exponentially with the number of threads. If you have two threads, each executing n instructions, then there are 2^n possible "interleavings" of those instructions. Of course, many of those interleavings will have identical behavior, but several won't. Not only does this make understanding how a program works an order of magnitude harder, but it will also result in irreproducible, non-deterministic, bugs. And of course, the problem will be many times worse when you have a hundred or a thousand threads. So what is the answer? All of the possible alternatives require a change in the way we write programs and, currently, seem to be plagued by performance issues. Software transactional memory (STM) applies the ideas of database transactions, and optimistic concurrency control, to memory. However, working out how to break down your program into sufficiently small transactions, so as to avoid contention issues, isn't easy. Another approach is concurrency with actors, where instead of having threads share memory, each thread runs in complete isolation, and communicates with others by passing messages. It simplifies concurrent programs but still has performance issues, if the threads need to operate on the same large piece of data. There are doubtless other possible solutions that I haven't mentioned, and I would love to know to what extent you, as a developer, are considering the problem of multi-core concurrency, what solution you currently favor, and why. Cheers, Tony.

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• Refresh RadGridview when Insert,Update and Delete Operation done on Database in WPF

  - by patelriki13

  WPF and C#: Problem: 1. How to Refresh Radgridview when i Insert,update and Delete Record in database anrecord. 2.when i am Insert or Update Record than in radgridview that row is selected. i am useing sql server 2005. i am use to set data source of radgridview like " radgridview1.ItemsSource = ds; " == ds is dataset. i am beginner so if possible than tel me by code it is easy to understand....... can u help me as early as possible .... i give some code which i am useing for update RadGridview con.ConnectionString = @"Data Source=(local);Initial Catalog=DigiDms;Integrated Security=True"; cmd1.Connection = con; con.Open(); cmd1.CommandType = CommandType.StoredProcedure; cmd1.CommandText = "Pro_Insurance_Master_Select"; da1.SelectCommand = cmd1; da1.Fill(ds1); con.Close(); //dataGrid.clear(); //dsGrid.Reset(); //dsGrid = dataGrid.GetData("Pro_Insurance_Master_Select"); //set datasource of gridview gridShowData.ItemsSource = null; gridShowData.ItemsSource = ds1; doing this , when i am delete or update record than folloning error generated... Error: "Object reference not set to an object" when i am doing the "gridShowData.ItemsSource = null;" and when i am doing insert operation than this error is not generated and RadGridview also updated..... so pls help me as early as possible.... i am beginer ........ my email address is [email protected]

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• Solving Diophantine Equations Using Python

  - by HARSHITH

  In mathematics, a Diophantine equation (named for Diophantus of Alexandria, a third century Greek mathematician) is a polynomial equation where the variables can only take on integer values. Although you may not realize it, you have seen Diophantine equations before: one of the most famous Diophantine equations is: We are not certain that McDonald's knows about Diophantine equations (actually we doubt that they do), but they use them! McDonald's sells Chicken McNuggets in packages of 6, 9 or 20 McNuggets. Thus, it is possible, for example, to buy exactly 15 McNuggets (with one package of 6 and a second package of 9), but it is not possible to buy exactly 16 nuggets, since no non- negative integer combination of 6's, 9's and 20's adds up to 16. To determine if it is possible to buy exactly n McNuggets, one has to solve a Diophantine equation: find non-negative integer values of a, b, and c, such that 6a + 9b + 20c = n. Write an iterative program that finds the largest number of McNuggets that cannot be bought in exact quantity. Your program should print the answer in the following format (where the correct number is provided in place of n): "Largest number of McNuggets that cannot be bought in exact quantity: n"

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• Boosting my GA with Neural Networks and/or Reinforcement Learning

  - by AlexT

  As I have mentioned in previous questions I am writing a maze solving application to help me learn about more theoretical CS subjects, after some trouble I've got a Genetic Algorithm working that can evolve a set of rules (handled by boolean values) in order to find a good solution through a maze. That being said, the GA alone is okay, but I'd like to beef it up with a Neural Network, even though I have no real working knowledge of Neural Networks (no formal theoretical CS education). After doing a bit of reading on the subject I found that a Neural Network could be used to train a genome in order to improve results. Let's say I have a genome (group of genes), such as 1 0 0 1 0 1 0 1 0 1 1 1 0 0... How could I use a Neural Network (I'm assuming MLP?) to train and improve my genome? In addition to this as I know nothing about Neural Networks I've been looking into implementing some form of Reinforcement Learning, using my maze matrix (2 dimensional array), although I'm a bit stuck on what the following algorithm wants from me: (from http://people.revoledu.com/kardi/tutorial/ReinforcementLearning/Q-Learning-Algorithm.htm) 1. Set parameter , and environment reward matrix R 2. Initialize matrix Q as zero matrix 3. For each episode: * Select random initial state * Do while not reach goal state o Select one among all possible actions for the current state o Using this possible action, consider to go to the next state o Get maximum Q value of this next state based on all possible actions o Compute o Set the next state as the current state End Do End For The big problem for me is implementing a reward matrix R and what a Q matrix exactly is, and getting the Q value. I use a multi-dimensional array for my maze and enum states for every move. How would this be used in a Q-Learning algorithm? If someone could help out by explaining what I would need to do to implement the following, preferably in Java although C# would be nice too, possibly with some source code examples it'd be appreciated.

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• Foreign keys in django admin list display

  - by Olivier

  If a django model contains a foreign key field, and if that field is shown in list mode, then it shows up as text, instead of displaying a link to the foreign object. Is it possible to automatically display all foreign keys as links instead of flat text? (of course it is possible to do that on a field by field basis, but is there a general method?) Example: class Author(models.Model): ... class Post(models.Model): author = models.ForeignKey(Author) Now I choose a ModelAdmin such that the author shows up in list mode: class PostAdmin(admin.ModelAdmin): list_display = [..., 'author',...] Now in list mode, the author field will just use the __unicode__ method of the Author class to display the author. On the top of that I would like a link pointing to the url of the corresponding author in the admin site. Is that possible? Manual method: For the sake of completeness, I add the manual method. It would be to add a method author_link in the PostAdmin class: def author_link(self, item): return '<a href="../some/path/%d">%s</a>' % (item.id, unicode(item)) author_link.allow_tags = True That will work for that particular field but that is not what I want. I want a general method to achieve the same effect. (One of the problems is how to figure out automatically the path to an object in the django admin site.)

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• How do you protect against specific CSRF attack

  - by Saif Bechan

  I am going trough the OWASP Top 10 list of 2007 and 2010. I stumbled upon Cross Site Request Forgery (CSRF) this is often called session riding as you let the user usee his session to fulfill your wishes. Now a solution to this is adding a token to every url and this token is checked for every link. For example to vote on product x the url would be: 'http://mysite.com?token=HVBKJNKL' This looks like a solid solution to because a hacker can not guess the token. But I was thinking of the following scenario(I do not know if it is possible): You create a website with an hidden iFrame or div. After that you can load my website in it either using just the normal iFrame or ajax. When you have my website loaded hidden inside your website, and the user has a stored session, the following can be done. You can retrieve the token from the URLS, and still do all the actions needed. Is it possible to do something like this. Or is it not possible to do this cross domain.

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• YUV Textures and Shaders

  - by Luca

  I've always used RGB textures. Now comes up the need of use of YUV textures (a set of three texture, specifying 1 luminance and 2 chrominance channels). Of course the YUV texture could be converted on CPU, getting the RGB texture usable as usual... but I need to get RGB pixel directly on GPU, to avoid unnecessary processor load... The problem became strange, since I require to specifyin the shader source, because a single texture, the following items: Three samplers uniforms, one for each channel Two integer uniforms, for specifying the chrominance channels sampling a mat3 uniform, for specific YUV to RGB conversion matrix. This should be done for each YUV texture... Is it possible to "compress" required uniforms, and getting RGB values quite easily? Actually i think this could aid: Texture sizes, including mipmaps, could be queried. With this, its possible to save the two integer uniforms, since the uniform values are derived the ratio between texture extents The mat3 uniforms could be collected as globals, and with preprocessor could be selected. But what design should I use for specify three (related) textures? Is it possible to use textures levels for accessing multiple textures? Texture arrays could be usable? And what about using rectangle textures, which doesn't supports mipmaps? Maybe a shader abstraction (struct definition and related function) could aid? Thank you.

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• Can Sql Server BULK INSERT read from a named pipe/fifo?

  - by Peter

  Is it possible for BULK INSERT/bcp to read from a named pipe, fifo-style? That is, rather than reading from a real text file, can BULK INSERT/bcp be made to read from a named pipe which is on the write end of another process? For example: create named pipe unzip file to named pipe read from named pipe with bcp or BULK INSERT or: create 4 named pipes split 1 file into 4 streams, writing each stream to a separate named pipe read from 4 named pipes into 4 tables w/ bcp or BULK INSERT The closest I've found was this fellow (site now unreachable), who managed to write to a named pipe w/ bcp, with a his own utility and usage like so: start /MIN ZipPipe authors_pipe authors.txt.gz 9 bcp pubs..authors out \\.\pipe\authors_pipe -T -n But he couldn't get the reverse to work. So before I head off on a fool's errand, I'm wondering whether it's fundamentally possible to read from a named pipe w/ BULK INSERT or bcp. And if it is possible, how would one set it up? Would NamedPipeServerStream or something else in the .NET System.IO.Pipes namespace be adequate? eg, an example using Powershell: [reflection.Assembly]::LoadWithPartialName("system.core") $pipe = New-Object system.IO.Pipes.NamedPipeServerStream("Bob") And then....what?

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• How can an iPhone access another non-iPhone device over wireless or bluetooth?

  - by Tai Squared

  I'm trying to figure out if an iPhone can connect to another non-iPhone device over wireless or bluetooth and have seen conflicting information. Much of what I've found was before version 3.0 of the SDK came out, when it certainly wasn't possible. Looking at questions like this mention you can't connect to an arbitrary device unless if it's part of the "Works for iPhone" device. Do I need hardware that is part of this program? Looking through the Apple documentation, it mentions connecting two iPhones, not an iPhone to another Bluetooth device. Then there are articles like this that includes this quote ...and with the newly-announced "standard support" should allow file transfer between the iPhone and a computer, as well as between nearby iPhones Other questions mention Bonjour, and the Apple documentation talk about connecting to Bonjour devices, but can an iPhone connect to any Bonjour device? Does it have to have a wifi connection, or can it use Bluetooth? Even if I could use Bluetooth to connect to another device, it won't be available on first generation iPhones and iTouches, I believe. Is that correct? I'm thinking of an iPhone application that would need to communicate with other non-iPhone devices in the area, probably using Bluetooth, but possibly a direct wireless connection. What are the possibilities and limitations of this approach? Is it not possible to have an iPhone connect to an arbitrary Bluetooth device? Does the other device have to be on a wireless Bonjour network that? I'm trying to figure out if it's even possible for this to work or if it's not worth the effort.

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• Can you use gzip over SSL? And Connection: Keep-Alive headers

  - by magenta

  I'm evaluating the front end performance of a secure (SSL) web app here at work and I'm wondering if it's possible to compress text files (html/css/javascript) over SSL. I've done some googling around but haven't found anything specifically related to SSL. If it's possible, is it even worth the extra CPU cycles since responses are also being encrypted? Would compressing responses hurt performance? Also, I'm wanting to make sure we're keeping the SSL connection alive so we're not making SSL handshakes over and over. I'm not seeing Connection: Keep-Alive in the response headers. I do see Keep-Alive: 115 in the request headers but that's only keeping the connection alive for 115 milliseconds (seems like the app server is closing the connection after a single request is processed?) Wouldn't you want the server to be setting that response header for as long as the session inactivity timeout is? I understand browsers don't cache SSL content to disk so we're serving the same files over and over and over on subsequent visits even though nothing has changed. The main optimization recommendations are reducing the number of http requests, minification, moving scripts to bottom, image optimization, possible domain sharding (though need to weigh the cost of another SSL handshake), things of that nature.

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• Force x86 CLR on 'Any CPU' .NET assembly

  - by jeffora

  In .NET, the 'Platform Target: Any CPU' compiler option allows a .NET assembly to run as 64bit on a x64 machine, and 32bit on an x86 machine. It is also possible to force an assembly to run as x86 on an x64 machine using the 'Platform Target: x86' compiler option. Is it possible to run an assembly with the 'Any CPU' flag, but determine whether it should be run in the x86 or x64 CLR? Normally this decision is made by the CLR/OS Loader (as is my understanding) based on the bitness of the underlying system. I am trying to write a C# .NET application that can interact with (read: inject code into) other running processes. x64 processes can only inject into other x64 processes, and the same with x86. Ideally, I would like to take advantage of JIT compilation and the Any CPU option to allow a single application to be used to inject into either x64 or x86 processes (on an x64 machine). The idea is that the application would be compiled as Any CPU. On an x64 machine it would run as x64. If the target process is x86, it should relaunch itself, forcing the CLR to run it as x86. Is this possible?

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• CakePHP, CodeIgniter or Rails for multi-user Tumblr clone?

  - by Jordan

  I'm about to start building a tumblr clone that handles multiple users (so premade clones like Gelato won't cut it) and I'm not sure which framework I'd like to build this is. Right now, I'm only intending to build a prototype. Something I can get a dozen friends on to test the concept and grow to maybe a couple hundred users to prove the market, so I'm not worried about long term scale. My biggest concern right now is quick deployment. I'd like to get from zero to signups in as short a time as possible, with as little customization to the framework of choice as possible. I have experience with PHP, but not Ruby. However, I don't think the learning curve would be too steep so I'm not ruling out rails. I just want the framework that is most appropriate for a system like a multi-user tumblr clone so that I can build it with as little hassle, and as quickly, as possible. If anyone has experience with a similar project, or with these frameworks and can offer an insightful perspective, I'd be very appreciative. Thanks for taking the time to read. Cheers, ~Jordan Feldstein

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• Add a custom variable to an email header already within a gmail inbox

  - by Ali

  Hi guys - this may seem odd but I was wondering if it was possible to add custom header details to emails already in an inbox. Like lets say I wish to add in the Header of the email something like - myvariable = myvalue and then be able to query it somehow. I'm looking at code from Iloha mail and most of the details like subject and from recieved etc are in the headers and you can search through them. SO is it possible to add my own custom variable to an email header and query it in the same way? How can it be done using php? EDIT ==================== Thanks I know how you can modify the headers of sent messages plus also query for custom variables in message headers however in this case I want to know if it would be possible to add a custom variable in a recieved message already in my inbox. Actually let me define the situation here. I'm working on a google apps solution which requires maintaining references to emails. Basically the application is as such that when an email comes in - we create an order from that email and wish to maintain a reference to that EXACT email by some kind of identifier which would enable us to identify that email. The fact is that we don't want to download the emails in a database and maintain a separate store as we would want to keep all the emailing on GMAIL. We just need: A way to be able to 'link' to a specific email permanently - the UID is just a sequence number and not very reliable. We couldn't find any property of emails that could function as a unique ID or primary key and so we thought if we could instead generate a key on our end and store it in a custom variable on the email itself. However it seems unfortunately that there isn't a way to manipulate headers of an already existing email. :( is there any solution to this problem I could use any IDEA !

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• Maths Question: number of different permutations

  - by KingCong

  This is more of a maths question than programming but I figure a lot of people here are pretty good at maths! :) My question is: Given a 9 x 9 grid (81 cells) that must contain the numbers 1 to 9 each exactly 9 times, how many different grids can be produced. The order of the numbers doesn't matter, for example the first row could contain nine 1's etc. This is related to Sudoku and we know the number of valid Sudoku grids is 6.67×10^21, so since my problem isn't constrained like Sudoku by having to have each of the 9 numbers in each row, column and box then the answer should be greater than 6.67×10^21. My first thought was that the answer is 81! however on further reflection this assume that the 81 number possible for each cell are different, distinct number. They are not, there are 81 possible numbers for each cell but only 9 possible different numbers. My next thought was then that each of the cells in the first row can be any number between 1 and 9. If by chance the first row happened to be all the same number, say all 1s, then each cell in the second row could only have 8 possibilites, 2-9. If this continued down until the last row then number of different permutations could be calculated by 9^2 * 8^2 * 7^2 ..... * 1^2. However this doesn't work if each row doesn't contain 9 of the same number. It's been quite a while since I studied this stuff and I can't think of a way to work it out, I'd appreciate any help anyone can offer.

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• Getting browser to make an AJAX call ASAP, while page is still loading

  - by Chris

  I'm looking for tips on how to get the browser to kick off an AJAX call as soon as possible into processing a web page, ideally before the page is fully downloaded. Here's my approximate motivation: I have a web page that takes, say, 5 seconds to load. It calls a web service that takes, say, 10 seconds to load. If loading the page and calling the web service happened sequentially, the user would have to wait 15 seconds to see all the information. However, if I can get the web service call started before the 5 second page load is complete, then at least some of the work can happened in parallel. Ideally I'd like as much of the work to happen in parallel as possible. My initial theory was that I should place the AJAX-calling javascript as high up as possible in the web page HTML source (being mindful of putting it after the jquery.js include, because I'm making the call using jquery ajax). I'm also being mindful not to wrap the AJAX call in a jquery ready event handler. (I mention this because ready events are popular in a lot of jquery example code.) However, the AJAX call still doesn't seem to get kicked off as early as I'm hoping (at least as judged by the Google Chrome "Timeline" feature), so I'm wondering what other considerations apply. One thing that might potentially be detrimental is that the AJAX call is back to the same web server that's serving the original web page, so I might be in danger of hitting a browser limit on the # of HTTP connections back to that one machine? (The HTML page loads a number of images, css files, etc..)

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• R: dev.copy2pdf, multiple graphic devices to a single file, how to append to file?

  - by Timtico

  Hi everybody, I have a script that makes barplots, and opens a new window when 6 barplots have been written to the screen and keeps opening new graphic devices whenever necessary. Depending on the input, this leaves me with a potential large number of openened windows (graphic devices) which I would like to write to a single PDF file. Considering my Perl background, I decided to iterate over the different graphics devices, printing them out one by one. I would like to keep appending to a single PDF file, but I do not know how to do this, or if this is even possible. I would like to avoid looping in R. :) The code I use: for (i in 1:length(dev.list()) { dev.set(which = dev.list()[i] dev.copy2pdf(device = quartz, file = "/Users/Tim/Desktop/R/Filename.pdf") } However, this is not working as it will overwrite the file each time. Now is there an append function in R, like there is in Perl. Which allows me to keep adding pages to the existing pdf file? Or is there a way to contain the information in a graphic window to a object, and keep adding new graphic devices to this object and finally print the whole thing to a file? Other possible solutions I thought about: writing different pdf files, combining them after creation (perhaps even possible in R, with the right libraries installed?) copying the information in all different windows to one big graphic device and then print this to a pdf file.

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• Which type of file parsing easiest and efficient and good ?(html,pdf,csv,text)

  - by Harikrishna

  I want to parse the html file, pdf file, csv file and text file. Now parsing for which type of file (specified above) is easiest and efficient ? Like parsing for html file is easiest and efficient OR parsing for pdf file is easiest and efficient OR parsing for csv file is easiest and efficient ? I am asking this question because I want to parse pdf ,html ,csv and text file through common parsing code if possible. And now suppose if parsing for html is easiest and efficient then : I will write the parsing code for html file and will try to convert pdf file to the html file(if possible)so the code written for parsing html file will also work for pdf file also. And thus I will try to convert pdf,csv and text file to html file.And write the code for parsing html file and thus this code will parse html,pdf,csv and text file. Suppose if parsing for pdf is easiest and efficient then : I will convert html,csv and text file to pdf and write the code for parsing pdf file.So the code for parsing pdf file can parse html,csv and text file. So my question is (1) Which type of file parsing is easiest and efficient (pdf,csv,html,text) ? (2) And converting files(pdf,text,html,csv) to eachother is possible. Like if html parsing easiest then pdf to html,text to html and csv to html.

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• vimscript: calling dictionary functions with call()

  - by intuited

  I'm hoping to call a "static" dictionary function using call(). By "static" I mean that the keyword 'dict' is not used in the function's definition. I use this nomenclature in the hopes that the effect of this keyword is to declare a static member function as is possible in java/C++/etc, ie to put the function name in the class namespace but allow it to be called without referencing an object. However this doesn't seem to work. For example: " Setup: let testdict = { } funct! testdict.funct() echo "called" endfunct " Tests: " Following each line is an indented comment " containing its output in message land, ie what was echoed. call testdict.funct() " called echo testdict.funct " 667 echo string(testdict.funct) " function('667') echo function('667') " E475: Invalid argument: 667 echo function('testdict.funct') " testdict.funct call call(testdict.funct, [ ]) " E725: Calling dict function without Dictionary: 667 " Same deal if there's an intermediate variable involved. let TestdictDotFunct = testdict.funct echo TestdictDotFunct " 667 echo string(TestdictDotFunct) " function('667') call TestdictDotFunct() " E725: Calling dict function without Dictionary: 667 From the help topic E725: It is also possible to add a function without the "dict" attribute as a Funcref to a Dictionary, but the "self" variable is not available then. So logic would seem to indicate that if "self" is not available, then it should be possible to call the function referenced by the Funcref without a Dictionary. However this doesn't seem to be the case. Am I missing something? Vim version info: $ aptitude show vim-gnome Package: vim-gnome State: installed Automatically installed: no Version: 2:7.2.245-2ubuntu2

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• Multiselect Form Field in PDF

  - by Jason R. Coombs

  Using PDF, is it possible to create a single form element with multiple fields of which several can be selected? For example, in HTML, one can create a set of checkboxes associated with the same field name: <div>Select one for Member of the School Board</div> <input type="checkbox" name="field(school)" value="vote1"> <span class="label">Libby T. Garvey</span><br/> <input type="checkbox" name="field(school)" value="vote2"> <span class="label">Emma N. Violand-Sanchez</span><br/> In this case, the field name is "field(school)", and when the form is submitted, "field(school)" can be supplied 0, 1, or 2 times. Is there an equivalent construct in PDF where a single field can have multiple values. So far in my investigation, it appears that if fields are assigned the same name, it is only possible to select one field. If it is possible to implement this in PDF, what is this construct called and how can it be implemented? Edit: To clarify, I am aware that a PDF can contain multiple form fields with different field names, and those can be selected independently, but then the grouping is implicit and not explicit as with the HTML form. I would like to use a construct that makes the grouping of options explicit, and preferably allows for restrictions (e.g. at least one required, no more than 2 allowed, etc).

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• reconstructing a tree from its preorder and postorder lists.

  - by NomeN

  Consider the situation where you have two lists of nodes of which all you know is that one is a representation of a preorder traversal of some tree and the other a representation of a postorder traversal of the same tree. I believe it is possible to reconstruct the tree exactly from these two lists, and I think I have an algorithm to do it, but have not proven it. As this will be a part of a masters project I need to be absolutely certain that it is possible and correct (Mathematically proven). However it will not be the focus of the project, so I was wondering if there is a source out there (i.e. paper or book) I could quote for the proof. (Maybe in TAOCP? anybody know the section possibly?) In short, I need a proven algorithm in a quotable resource that reconstructs a tree from its pre and post order traversals. Note: The tree in question will probably not be binary, or balanced, or anything that would make it too easy. Note2: Using only the preorder or the postorder list would be even better, but I do not think it is possible. Note3: A node can have any amount of children. Note4: I only care about the order of siblings. Left or right does not matter when there is only one child.

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