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• All hail the Excel Queen

  - by Tim Dexter

  An excellent question this past week from dear ol Blighty; actually from Brian at Nextgen Clearing Ltd in the big smoke (London). Brian was developing an excel template and wanted to be able to reference the data fields multiple times inside the Excel template. Damn good question and I of course has some wacky solutions, from macros and cell referencing in Excel to pre-processing the data with an XSL stylesheet to copy the data multiple times so it could be referenced multiple times. All completely outlandish, enter our Queen of Excel, Shirley from the development team. Shirley is singlehandedly responsible for the Excel templates, I put her through six months of hell a few years back, with a host of Excel template requirements. She was more than up to the challenge and has developed some great features. One of those, is the ability to use the hidden XDO_METADATA sheet to map the data to custom named fields so they can be used multiple times in the template. So simple and very neat! Excel template and regular Excel users will know that you can only use the naming function once ie the names have to be unique across the workbook so you can not reuse a cell/group name. To get around this you can just come up with as many cell names as you want and map them in the XDO_METADATA sheet to the data columns/fields in your XML data set:. For example: XDO_?DEPTNO_SUMMARY?  <?DEPTNO?> XDO_?DNAME_SUMMARY?  <?DNAME?> XDO_GROUP_?G_D_DETAIL? <xsl:for-each-group select=".//G_D" group-by="./DEPTNO"> XDO_?DEPTNO_DETAIL? <?DEPTNO?> As you can see DEPTNO has been referenced twice and mapped to different named values in the left hand column. These values can then be used to name individual cells in the Excel template. You'll also notice a mix of Publisher <? ...?> and native XSL commands. So the world is your oyster on the mapping and the complexity you might need for calculations or string manipulation. Shirley has kindly built out a sample Excel template, data and result here so you can see how it all hangs together. the XDO_METADATA sheet is hidden, just right click on the sheet names and use the Unhide command to show it.

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• Create simple jQuery plugin

  - by ybbest

  In the last post, I have shown you how to add the function to jQuery. In this post, I will show you how to create plugin to achieve this. 1. You need to wrap your code in the following construct, this is because you should not use $ directly as $ is global variable, it could have clash with some other library which also use $.Basically, you can pass in jQuery object into the function, so that $ is made available inside the function. (JavaScript use function to create scope, so you can make sure $ is referred to jQuery inside the function ) (function($){ //Your code goes here. }; })(jQuery); 2. Put your code into the construct above. (function ($) { $.getParameterByName = function (name) { name = name.replace(/[\[]/, "\\\[").replace(/[\]]/, "\\\]"); var regexS = "[\\?&]" + name + "=([^&#]*)"; var regex = new RegExp(regexS); var results = regex.exec(window.location.search); if (results == null) return ""; else return decodeURIComponent(results[1].replace(/\+/g, " ")); }; })(jQuery); 3. Now you can reference the code into you project and you can call the method in you JavaScript References: Provides scope for variables Variables are scoped at the function level in javascript. This is different to what you might be used to in a language like C# or Java where the variables are scoped to the block. What this means is if you declare a variable inside a loop or an if statement, it will be available to the entire function. If you ever find yourself needing to explicitly scope a variable inside a function you can use an anonymous function to do this. You can actually create an anonymous function and then execute it straight away and all the variables inside will be scoped to the anonymous function: (function() { var myProperty = "hello world"; alert(myProperty); })(); alert(typeof(myProperty)); // undefined How does an anonymous function in JavaScript work? Building Your First jQuery Plugin A Plugin Development Pattern

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• Accounting for waves when doing planar reflections

  - by CloseReflector

  I've been studying Nvidia's examples from the SDK, in particular the Island11 project and I've found something curious about a piece of HLSL code which corrects the reflections up and down depending on the state of the wave's height. Naturally, after examining the brief paragraph of code: // calculating correction that shifts reflection up/down according to water wave Y position float4 projected_waveheight = mul(float4(input.positionWS.x,input.positionWS.y,input.positionWS.z,1),g_ModelViewProjectionMatrix); float waveheight_correction=-0.5*projected_waveheight.y/projected_waveheight.w; projected_waveheight = mul(float4(input.positionWS.x,-0.8,input.positionWS.z,1),g_ModelViewProjectionMatrix); waveheight_correction+=0.5*projected_waveheight.y/projected_waveheight.w; reflection_disturbance.y=max(-0.15,waveheight_correction+reflection_disturbance.y); My first guess was that it compensates for the planar reflection when it is subjected to vertical perturbation (the waves), shifting the reflected geometry to a point where is nothing and the water is just rendered as if there is nothing there or just the sky: Now, that's the sky reflecting where we should see the terrain's green/grey/yellowish reflection lerped with the water's baseline. My problem is now that I cannot really pinpoint what is the logic behind it. Projecting the actual world space position of a point of the wave/water geometry and then multiplying by -.5f, only to take another projection of the same point, this time with its y coordinate changed to -0.8 (why -0.8?). Clues in the code seem to indicate it was derived with trial and error because there is redundancy. For example, the author takes the negative half of the projected y coordinate (after the w divide): float waveheight_correction=-0.5*projected_waveheight.y/projected_waveheight.w; And then does the same for the second point (only positive, to get a difference of some sort, I presume) and combines them: waveheight_correction+=0.5*projected_waveheight.y/projected_waveheight.w; By removing the divide by 2, I see no difference in quality improvement (if someone cares to correct me, please do). The crux of it seems to be the difference in the projected y, why is that? This redundancy and the seemingly arbitrary selection of -.8f and -0.15f lead me to conclude that this might be a combination of heuristics/guess work. Is there a logical underpinning to this or is it just a desperate hack? Here is an exaggeration of the initial problem which the code fragment fixes, observe on the lowest tessellation level. Hopefully, it might spark an idea I'm missing. The -.8f might be a reference height from which to deduce how much to disturb the texture coordinate sampling the planarly reflected geometry render and -.15f might be the lower bound, a security measure.

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• Understanding the levels of computing

  - by RParadox

  Sorry, for my confused question. I'm looking for some pointers. Up to now I have been working mostly with Java and Python on the application layer and I have only a vague understanding of operating systems and hardware. I want to understand much more about the lower levels of computing, but it gets really overwhelming somehow. At university I took a class about microprogramming, i.e. how processors get hard-wired to implement the ASM codes. Up to now I always thought I wouldn't get more done if learned more about the "low level". One question I have is: how is it even possible that hardware gets hidden almost completely from the developer? Is it accurate to say that the operating system is a software layer for the hardware? One small example: in programming I have never come across the need to understand what L2 or L3 Cache is. For the typical business application environment one almost never needs to understand assembler and the lower levels of computing, because nowadays there is a technology stack for almost anything. I guess the whole point of these lower levels is to provide an interface to higher levels. On the other hand I wonder how much influence the lower levels can have, for example this whole graphics computing thing. So, on the other hand, there is this theoretical computer science branch, which works on abstract computing models. However, I also rarely encountered situations, where I found it helpful thinking in the categories of complexity models, proof verification, etc. I sort of know, that there is a complexity class called NP, and that they are kind of impossible to solve for a big number of N. What I'm missing is a reference for a framework to think about these things. It seems to me, that there all kinds of different camps, who rarely interact. The last few weeks I have been reading about security issues. Here somehow, much of the different layers come together. Attacks and exploits almost always occur on the lower level, so in this case it is necessary to learn about the details of the OSI layers, the inner workings of an OS, etc.

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• Criteria for a programming language to be considered "mature"

  - by Giorgio

  I was recently reading an answer to this question, and I was struck by the statement "The language is mature". So I was wondering what we actually mean when we say that "A programming language is mature"? Normally, a programming language is initially developed out of a need, e.g. Try out / implement a new programming paradigm or a new combination of features that cannot be found in existing languages. Try to solve a problem or overcome a limitation of an existing language. Create a language for teaching programming. Create a language that solves a particular class of problems (e.g. concurrency). Create a language and an API for a special application field, e.g. the web (in this case the language might reuse a well-known paradigm, but the whole API must be new). Create a language to push your competitor out of the market (in this case the creator might want the new language to be very similar to an existing one, in order to attract developers to the new programming language and platform). Regardless of what the original motivation and scenario in which a language has been created, eventually some languages are considered mature. In my intuition, this means that the language has achieved (at least one of) its goals, e.g. "We can now use language X as a reliable tool for writing web applications." This is however a bit vague, so I wanted to ask what you consider the most important criteria (if any) that are applied when saying that a language is mature. IMPORTANT NOTE This question is (on purpose) language-agnostic because I am only interested in general criteria. Please write only language-agnostic answers and comments! I am not asking whether any specific "language X is mature" or "which programming languages can be considered mature", or whether "language X is more mature than language Y": please avoid posting any opinions or reference about any specific languages because these are out of the scope of this question. EDIT To make the question more precise, by criteria I mean such things as "tool support", "adoption by the industry", "stability", "rich API", "large user community", "successful application record", "standardization", "clean and uniform semantics", and so on.

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• How can I cleanly and elegantly handle data and dependancies between classes

  - by Neophyte

  I'm working on 2d topdown game in SFML 2, and need to find an elegant way in which everything will work and fit together. Allow me to explain. I have a number of classes that inherit from an abstract base that provides a draw method and an update method to all the classes. In the game loop, I call update and then draw on each class, I imagine this is a pretty common approach. I have classes for tiles, collisions, the player and a resource manager that contains all the tiles/images/textures. Due to the way input works in SFML I decided to have each class handle input (if required) in its update call. Up until now I have been passing in dependencies as needed, for example, in the player class when a movement key is pressed, I call a method on the collision class to check if the position the player wants to move to will be a collision, and only move the player if there is no collision. This works fine for the most part, but I believe it can be done better, I'm just not sure how. I now have more complex things I need to implement, eg: a player is able to walk up to an object on the ground, press a key to pick it up/loot it and it will then show up in inventory. This means that a few things need to happen: Check if the player is in range of a lootable item on keypress, else do not proceed. Find the item. Update the sprite texture on the item from its default texture to a "looted" texture. Update the collision for the item: it might have changed shape or been removed completely. Inventory needs to be updated with the added item. How do I make everything communicate? With my current system I will end up with my classes going out of scope, and method calls to each other all over the place. I could tie up all the classes in one big manager and give each one a reference to the parent manager class, but this seems only slightly better. Any help/advice would be greatly appreciated! If anything is unclear, I'm happy to expand on things.

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• List of common pages to have in the footer [closed]

  - by user359650

  I would like to post this question as a reference for webmasters wondering what pages they should include in the footer. I will use answers to complete my initial list: About us / About MyCompany / MyCompany About / About us: description about the company, its mission, and its vision. History: summary of milestones achieved by the company. The team / Management / Board of directors: depending on size of the company there may be one of more pages describing the people involved in the company, depending on their position. Awards: list of awards received by the company if any. In the press / They're talking about us: list of links to external websites, usually highly regarded news websites, which mentioned the company in one of their articles. Media Wallpapers: wallpapers with company logo in different colors and formats that fans can set as desktop image for their computer. logos: company logo in different colors and formats that websites/blogs posting about the website can use for illustration purposes. Media kits: documents, usually in PDF format summarizing the key company figures and facts that journalists can download and read to get a quick overview of the company. Misc Contact / Contact us: contact details the company is prepared to disclose if any (address, email, phone) or contact form. Careers / Jobs / Join us: list of open vacancies with contact form to apply. Investors / Partners / Publishers: information and contact forms for companies willing to become Investors/Partners/Publishers or login page to access portal restricted to those who already are. FAQ: list of common questions and answers to guide users and reduce number of support requests. Follow us / Community Facebook / Twitter / Google+: links to the company's pages/accounts on various social networks. Legal Terms / Terms of use / Terms & Conditions: rules users must follow when browsing the website. Privacy / Privacy Statement: explanations as to how the company deals with users' personal data and what users can do about it (request information to be deleted...). cookies: page that starts appearing on more and more websites due to new regulation (notably EU) imposing more transparency and control for users about cookies (e.g. BBC cookie page). Any input is welcome PS: if someone with enough rep could add the footer tag that would be great (min. 300 required).

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• Trying to use stencils in 2D while retaining layer depth

  - by Steve

  This is a screen of what's going on just so you can get a frame of reference. http://i935.photobucket.com/albums/ad199/fobwashed/tilefloors.png The problem I'm running into is that my game is slowing down due to the amount of texture swapping I'm doing during my draw call. Since walls, characters, floors, and all objects are on their respective sprite sheet containing those types, per tile draw, the loaded texture is swapping no less than 3 to 5+ times as it cycles and draws the sprites in order to layer properly. Now, I've tried throwing all common objects together into their respective lists, and then using layerDepth drawing them that way which makes things a lot better, but the new problem I'm running into has to do with the way my doors/windows are drawn on walls. Namely, I was using stencils to clear out a block on the walls that are drawn in the shape of the door/window so that when the wall would draw, it would have a door/window sized hole in it. This is the way my draw was set up for walls when I was going tile by tile rather than grouped up common objects. first it would check to see if a door/window was on this wall. If not, it'd skip all the steps and just draw normally. Otherwise end the current spriteBatch Clear the buffers with a transparent color to preserve what was already drawn start a new spritebatch with stencil settings draw the door area end the spriteBatch start a new spritebatch that takes into account the previously set stencil draw the wall which will now be drawn with a hole in it end that spritebatch start a new spritebatch with the normal settings to continue drawing tiles In the tile by tile draw, clearing the depth/stencil buffers didn't matter since I wasn't using any layerDepth to organize what draws on top of what. Now that I'm drawing from lists of common objects rather than tile by tile, it has sped up my draw call considerably but I can't seem to figure out a way to keep the stencil system to mask out the area a door or window will be drawn into a wall. The root of the problem is that when I end a spriteBatch to change the DepthStencilState, it flattens the current RenderTarget and there is no longer any depth sorting for anything drawn further down the line. This means walls always get drawn on top of everything regardless of depth or positioning in the game world and even on top of each other as the stencil has to happen once for every wall that has a door or window. Does anyone know of a way to get around this? To boil it down, I need a way to draw having things sorted by layer depth while also being able to stencil/mask out portions of specific sprites.

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• JCP.next.3: time to get to work

  - by Patrick Curran

  As I've previously reported in this blog, we planned three JSRs to improve the JCP’s processes and to meet our members’ expectations for change. The first - JCP.next.1, or more formally JSR 348: Towards a new version of the Java Community Process - was completed in October 2011. This focused on a small number of simple but important changes to make our process more transparent and to enable broader participation. We're already seeing the benefits of these changes as new and existing JSRs adopt the new requirements. However, because we wanted to complete this JSR quickly we deliberately postponed a number of more complex items, including everything that would require modifying the JSPA (the legal agreement that members sign when they join the organization) to a follow-on JSR. The second JSR (JSR 355: JCP Executive Committee Merge) is in progress now and will complete later this year. This JSR is even simpler than the first, and is focused solely on merging the two Executive Committees into one for greater efficiency and to encourage synergies between the Java ME and Java SE platforms. Continuing the momentum to move Java and the JCP forward we have just filed the third JSR (JCP.next.3) as JSR 358: A major revision of the Java Community Process. This JSR will modify the JSPA as well as the Process Document, and will tackle a large number of complex issues, many of them postponed from JSR 348. For these reasons we expect to spend a considerable amount of time working on it - at least a year, and probably more. The current version of the JSPA was created back in 2002, although some minor changes were introduced in 2005. Since then the organization and the environment in which we operate have changed significantly, and it is now time to revise our processes to ensure that they meet our current needs. We have a long list of topics to be considered, including the role of independent implementations (those not derived from the Reference Implementation), licensing and open source, ensuring that our new transparency requirements are implemented correctly, compatibility policy and TCKs, the role of individual members, patent policy, and IP flow. The Expert Group for JSR 358, as with all process-change JSRs, consists of all members of the Executive Committees. Even though the JSR has just been filed we started discussions on the various topics several months ago (see the EC's meeting minutes for details) and our EC members - including the new members who joined within the last year or two - are actively engaged. Now it's your opportunity to get involved. As required by version 2.8 of our Process (introduced with JSR 348) we will conduct all our business in the open. We have a public java.net project where you can follow and participate in our work. All of our deliberations will be copied to a public Observer mailing list, we'll track our issues on a public Issue Tracker, and all our documents (meeting agendas and minutes, task lists, working drafts) will be published in our Document Archive. We're just getting started, but we do want your input. Please visit us on java.net where you can learn how to participate. Let's get to work...

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• WebLogic Partner Community Newsletter September 2012

  - by JuergenKress

  Dear WebLogic partner community member Happy Birthday to our WebLogic partner Community! We launched the community a year ago, it is growing fast with almost 1,000 members and with a significant impact in our business. The WebLogic partner revenue grew significant last fiscal year. I would like to thank you for your contribution. It is indeed a great opportunity for your WebLogic service revenue, like consulting, implementation or training. There will be thousands of opportunities at our joint customer base, like iAs to WebLogic migration, J2EE platform consolidation or private clouds. We will continue to highlight these opportunities in our newsletter and offer you campaign kits. Please feel free to let us know if you are interested. I would also recommend you to give us your feedback in our WebLogic Partner Community Survey 2012! Your feedback is very important for us. We continue to offer free WebLogic 12c Bootcamps across Europe. Please make sure you register asap for your local training! In addition to this we plan to offer Exalogic 2.01 Bootcamp. If you are interested to attend it then please add your details to our wiki. Our ExaLogic kit is updated with ExaLogic 2.01 ppt & training & Installation check-list & tips & Web tier roadmap. In case you want to learn more about ExaLogic, please visit Qualogy virtual demo center. We have not only released the latest version of Tuxedo 12c but Andrejus also made a Performance Audit Tool - Runtime Diagnosis for ADF Applications which is available now. We uploaded the latest WebLogic 12c and Glassfish ppt presentation for your customer meetings to the WebLogic Community Workspace (WebLogic Community membership required). Are you ready and prepared for Oracle Open World 2012? Make sure you read our tips and enjoy the conference! WebLogic Server 11gR1 Interactive Quick Reference is a wonderful online overview. Make sure you do not miss it! If you want to try WebLogic why not in the Oracle Cloud - Java Cloud Service. Our Java Guru Adam Bien published a new book Real World Java EE Patterns. If you use Java on your machine, Please make sure that you update your Java SE. Jürgen Kress Oracle WebLogic Partner Adoption EMEA To read the newsletter please visit http://tinyurl.com/WebLogicnewsSeptember2012 (OPN Account required) To become a member of the WebLogic Partner Community please register at http://www.oracle.com/partners/goto/wls-emea ( OPN account required). If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Mix Forum Wiki Technorati Tags: WebLogic Community newsletter,newsletter,WebLogic,WebLogic Community,Oracle,OPN,Jürgen Kress

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• Is it appropriate to try to control the order of finalization?

  - by Strilanc

  I'm writing a class which is roughly analogous to a CancellationToken, except it has a third state for "never going to be cancelled". At the moment I'm trying to decide what to do if the 'source' of the token is garbage collected without ever being set. It seems that, intuitively, the source should transition the associated token to the 'never cancelled' state when it is about to be collected. However, this could trigger callbacks who were only kept alive by their linkage from the token. That means what those callbacks reference might now in the process of finalization. Calling them would be bad. In order to "fix" this, I wrote this class: public sealed class GCRoot { private static readonly GCRoot MainRoot = new GCRoot(); private GCRoot _next; private GCRoot _prev; private object _value; private GCRoot() { this._next = this._prev = this; } private GCRoot(GCRoot prev, object value) { this._value = value; this._prev = prev; this._next = prev._next; _prev._next = this; _next._prev = this; } public static GCRoot Root(object value) { return new GCRoot(MainRoot, value); } public void Unroot() { lock (MainRoot) { _next._prev = _prev; _prev._next = _next; this._next = this._prev = this; } } } intending to use it like this: Source() { ... _root = GCRoot.Root(callbacks); } void TransitionToNeverCancelled() { _root.Unlink(); ... } ~Source() { TransitionToNeverCancelled(); } but now I'm troubled. This seems to open the possibility for memory leaks, without actually fixing all cases of sources in limbo. Like, if a source is closed over in one of its own callbacks, then it is rooted by the callback root and so can never be collected. Presumably I should just let my sources be collected without a peep. Or maybe not? Is it ever appropriate to try to control the order of finalization, or is it a giant warning sign?

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• Entity Framework 5, separating business logic from model - Repository?

  - by bnice7

  I am working on my first public-facing web application and I’m using MVC 4 for the presentation layer and EF 5 for the DAL. The database structure is locked, and there are moderate differences between how the user inputs data and how the database itself gets populated. I have done a ton of reading on the repository pattern (which I have never used) but most of my research is pushing me away from using it since it supposedly creates an unnecessary level of abstraction for the latest versions of EF since repositories and unit-of-work are already built-in. My initial approach is to simply create a separate set of classes for my business objects in the BLL that can act as an intermediary between my Controllers and the DAL. Here’s an example class: public class MyBuilding { public int Id { get; private set; } public string Name { get; set; } public string Notes { get; set; } private readonly Entities _context = new Entities(); // Is this thread safe? private static readonly int UserId = WebSecurity.GetCurrentUser().UserId; public IEnumerable<MyBuilding> GetList() { IEnumerable<MyBuilding> buildingList = from p in _context.BuildingInfo where p.Building.UserProfile.UserId == UserId select new MyBuilding {Id = p.BuildingId, Name = p.BuildingName, Notes = p.Building.Notes}; return buildingList; } public void Create() { var b = new Building {UserId = UserId, Notes = this.Notes}; _context.Building.Add(b); _context.SaveChanges(); // Set the building ID this.Id = b.BuildingId; // Seed 1-to-1 tables with reference the new building _context.BuildingInfo.Add(new BuildingInfo {Building = b}); _context.GeneralInfo.Add(new GeneralInfo {Building = b}); _context.LocationInfo.Add(new LocationInfo {Building = b}); _context.SaveChanges(); } public static MyBuilding Find(int id) { using (var context = new Entities()) // Is this OK to do in a static method? { var b = context.Building.FirstOrDefault(p => p.BuildingId == id && p.UserId == UserId); if (b == null) throw new Exception("Error: Building not found or user does not have access."); return new MyBuilding {Id = b.BuildingId, Name = b.BuildingInfo.BuildingName, Notes = b.Notes}; } } } My primary concern: Is the way I am instantiating my DbContext as a private property thread-safe, and is it safe to have a static method that instantiates a separate DbContext? Or am I approaching this all wrong? I am not opposed to learning up on the repository pattern if I am taking the total wrong approach here.

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• Understanding implementation of glu.PickMatrix()

  - by stoney78us

  I am working on an OpenGL project which requires object selection feature. I use OpenTK framework to do this; however OpenTK doesn't support glu.PickMatrix() method to define the picking region. I ended up googling its implementation and here is what i got: void GluPickMatrix(double x, double y, double deltax, double deltay, int[] viewport) { if (deltax <= 0 || deltay <= 0) { return; } GL.Translate((viewport[2] - 2 * (x - viewport[0])) / deltax, (viewport[3] - 2 * (y - viewport[1])) / deltay, 0); GL.Scale(viewport[2] / deltax, viewport[3] / deltay, 1.0); } I totally fail to understand this piece of code. Moreover, this doesn't work with my following code sample: //selectbuffer private int[] _selectBuffer = new int[512]; private void Init() { float[] triangleVertices = new float[] { 0.0f, 1.0f, 0.0f, -1.0f, -1.0f, 0.0f, 1.0f, -1.0f, 0.0f }; float[] _triangleColors = new float[] { 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f }; GL.GenBuffers(2, _vBO); GL.BindBuffer(BufferTarget.ArrayBuffer, _vBO[0]); GL.BufferData(BufferTarget.ArrayBuffer, new IntPtr(sizeof(float) * _triangleVertices.Length), _triangleVertices, BufferUsageHint.StaticDraw); GL.VertexPointer(3, VertexPointerType.Float, 0, 0); GL.BindBuffer(BufferTarget.ArrayBuffer, _vBO[1]); GL.BufferData(BufferTarget.ArrayBuffer, new IntPtr(sizeof(float) * _triangleColors.Length), _triangleColors, BufferUsageHint.StaticDraw); GL.ColorPointer(3, ColorPointerType.Float, 0, 0); GL.EnableClientState(ArrayCap.VertexArray); GL.EnableClientState(ArrayCap.ColorArray); //Selectbuffer set up GL.SelectBuffer(512, _selectBuffer); } private void glControlWindow_Paint(object sender, PaintEventArgs e) { GL.Clear(ClearBufferMask.ColorBufferBit); GL.Clear(ClearBufferMask.DepthBufferBit); float[] eyes = { 0.0f, 0.0f, -10.0f }; float[] target = { 0.0f, 0.0f, 0.0f }; Matrix4 projection = Matrix4.CreatePerspectiveFieldOfView(0.785398163f, 4.0f / 3.0f, 0.1f, 100f); //45 degree = 0.785398163 rads Matrix4 view = Matrix4.LookAt(eyes[0], eyes[1], eyes[2], target[0], target[1], target[2], 0, 1, 0); Matrix4 model = Matrix4.Identity; Matrix4 MV = view * model; //First Clear Buffers GL.Clear(ClearBufferMask.ColorBufferBit); GL.Clear(ClearBufferMask.DepthBufferBit); GL.MatrixMode(MatrixMode.Projection); GL.LoadIdentity(); GL.LoadMatrix(ref projection); GL.MatrixMode(MatrixMode.Modelview); GL.LoadIdentity(); GL.LoadMatrix(ref MV); GL.Viewport(0, 0, glControlWindow.Width, glControlWindow.Height); GL.Enable(EnableCap.DepthTest); //Enable correct Z Drawings GL.DepthFunc(DepthFunction.Less); //Enable correct Z Drawings GL.MatrixMode(MatrixMode.Modelview); GL.PushMatrix(); GL.Translate(3.0f, 0.0f, 0.0f); DrawTriangle(); GL.PopMatrix(); GL.PushMatrix(); GL.Translate(-3.0f, 0.0f, 0.0f); DrawTriangle(); GL.PopMatrix(); //Finally... GraphicsContext.CurrentContext.VSync = true; //Caps frame rate as to not over run GPU glControlWindow.SwapBuffers(); //Takes from the 'GL' and puts into control } private void DrawTriangle() { GL.BindBuffer(BufferTarget.ArrayBuffer, _vBO[0]); GL.VertexPointer(3, VertexPointerType.Float, 0, 0); GL.EnableClientState(ArrayCap.VertexArray); GL.DrawArrays(BeginMode.Triangles, 0, 3); GL.DisableClientState(ArrayCap.VertexArray); } //mouse click event implementation private void glControlWindow_MouseClick(object sender, System.Windows.Forms.MouseEventArgs e) { //Enter Select mode. Pretend drawing. GL.RenderMode(RenderingMode.Select); int[] viewport = new int[4]; GL.GetInteger(GetPName.Viewport, viewport); GL.PushMatrix(); GL.MatrixMode(MatrixMode.Projection); GL.LoadIdentity(); GluPickMatrix(e.X, e.Y, 5, 5, viewport); Matrix4 projection = Matrix4.CreatePerspectiveFieldOfView(0.785398163f, 4.0f / 3.0f, 0.1f, 100f); // this projection matrix is the same as one in glControlWindow_Paint method. GL.LoadMatrix(ref projection); GL.MatrixMode(MatrixMode.Modelview); int i = 0; int hits; GL.PushMatrix(); GL.Translate(3.0f, 0.0f, 0.0f); GL.PushName(i); DrawTriangle(); GL.PopName(); GL.PopMatrix(); i++; GL.PushMatrix(); GL.Translate(-3.0f, 0.0f, 0.0f); GL.PushName(i); DrawTriangle(); GL.PopName(); GL.PopMatrix(); hits = GL.RenderMode(RenderingMode.Render); .....hits processing code goes here... GL.PopMatrix(); glControlWindow.Invalidate(); } I expect to get only one hit everytime i click inside a triangle, but i always get 2 no matter where i click. I suspect there is something wrong with the implementation of the GluPickMatrix, I haven't figured out yet.

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• How to write comments to explain the "why" behind the callback function when the function and parameter names are insufficient for that?

  - by snowmantw

  How should I approach writing comments for callback functions? I want to explain the "why" behind the function when the function and parameter names are insufficient to explain what's going on. I have always wonder why comments like this can be so ordinary in documents of libraries in dynamic languages: /** * cb: callback // where's the arguments & effects? */ func foo( cb ) Maybe the common attitude is "you can look into source code on your own after all" which pushes people into leaving minimalist comments like this. But it seems like there should be a better way to comment callback functions. I've tried to comment callbacks in Haskell way: /** * cb: Int -> Char */ func foo(cb) And to be fair, it's usually neat enough. But it gets into trouble when I need to pass some complex structure. The problem being partly due to the lack of type system: /** * cb: Int -> { err: String -> (), success: () -> Char } // too long... */ func foo(cb) Or I have tried this too: /** * cb: Int -> { err: String -> (), * success: () -> Char } // better ? */ func bar(cb) The problem is that you may put the structure in somewhere else, but you must give it a name to reference it. But then when you name a structure you're about to use immediately looks so redundant: // Somewhere else... // ResultCallback: { err: String -> (), success: () -> Char } /** * cb: Int -> ResultCallback // better ?? */ func foo(cb) And it bothers me if I follow the Java-doc like commenting style since it still seems incomplete. The comments don't tell you anything that you couldn't immediately see from looking at the function. /** * @param cb {Function} yeah, it's a function, but you told me nothing about it... * @param err {Function} where should I put this callback's argument ?? * Not to mention the err's own arguments... */ func foo(cb) These examples are JavaScript like with generic functions and parameter names, but I've encountered similar problems in other dynamic languages which allow complex callbacks.

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• "You are missing the following 32-bit libraries, and Steam may not run: libc.so.6" The common fixes don't work,

  - by M_Steam_User

  So I know this is a problem that has been asked around a lot, but I've tried a bunch of solutions with no success. I'm running Ubuntu 12.04 (64 bit), and I just installed it yesterday. This is my first time working with linux. The error is: You are missing the following 32-bit libraries, and Steam may not run: libc.so.6 Things I've tried. First, I had downloaded from the steam website. I uninstalled it, and tried again from the ubuntu software centre. sudo apt-get update sudo apt-get install ia32-libs sudo apt-get upgrade This installed a bunch of the 32 bit libraries, but did not fix the issue. This seems like the major fix for most people. The direct approach of sudo apt-get install libc.so.6 returns this: Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package libc.so.6 E: Couldn't find any package by regex 'libc.so.6' I guess libc.so.6 isn't a package, just a single file or something? I also tried gksudo gedit /etc/ld.so.conf.d/steam.conf Added these two lines, those the second one was all ready in the file, but copied over: /usr/lib32 /usr/lib/i386-linux-gnu/mesa Then executed: sudo ldconfig But nothing seemed to happen, steam still doesn't work. So, I feel like it is more likely that I have the library and steam isn't looking in the right place. One thing I've seen is people usually reference /usr/local/lib/ for your library locations. However, I can't find where to cd into /usr/, it isn't in my home folder. If /usr/ is the home folder, there is only a /.local folder which only has /share, no lib anywhere. Sorry for my linux ignorance. I appreciate any help, I honestly have no idea how to confirm I have the library and point steam to it, or if that is even the right thing to do. Edit: Tried this, not entirely sure what it means ~$ ls -l /lib32/libc* -rwxr-xr-x 1 root root 1721832 Sep 30 11:06 /lib32/libc-2.15.so -rw-r--r-- 1 root root 185928 Sep 30 11:06 /lib32/libcidn-2.15.so lrwxrwxrwx 1 root root 15 Sep 30 11:06 /lib32/libcidn.so.1 -> libcidn-2.15.so -rw-r--r-- 1 root root 34316 Sep 30 11:06 /lib32/libcrypt-2.15.so lrwxrwxrwx 1 root root 16 Sep 30 11:06 /lib32/libcrypt.so.1 -> libcrypt-2.15.so lrwxrwxrwx 1 root root 12 Sep 30 11:06 /lib32/libc.so.6 -> libc-2.15.so

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• Local LINQtoSQL Database For Your Windows Phone 7 Application

  - by Tim Murphy

  There aren’t many applications that are of value without having some for of data store.  In Windows Phone development we have a few options.  You can store text directly to isolated storage.  You can also use a number of third party libraries to create or mimic databases in isolated storage.  With Mango we gained the ability to have a native .NET database approach which uses LINQ to SQL.  In this article I will try to bring together the components needed to implement this last type of data store and fill in some of the blanks that I think other articles have left out. Defining A Database The first things you are going to need to do is define classes that represent your tables and a data context class that is used as the overall database definition.  The table class consists of column definitions as you would expect.  They can have relationships and constraints as with any relational DBMS.  Below is an example of a table definition. First you will need to add some assembly references to the code file. using System.ComponentModel;using System.Data.Linq;using System.Data.Linq.Mapping; You can then add the table class and its associated columns.  It needs to implement INotifyPropertyChanged and INotifyPropertyChanging.  Each level of the class needs to be decorated with the attribute appropriate for that part of the definition.  Where the class represents the table the properties represent the columns.  In this example you will see that the column is marked as a primary key and not nullable with a an auto generated value. You will also notice that the in the column property’s set method It uses the NotifyPropertyChanging and NotifyPropertyChanged methods in order to make sure that the proper events are fired. [Table]public class MyTable: INotifyPropertyChanged, INotifyPropertyChanging{ public event PropertyChangedEventHandler PropertyChanged; private void NotifyPropertyChanged(string propertyName) { if(PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } } public event PropertyChangingEventHandler PropertyChanging; private void NotifyPropertyChanging(string propertyName) { if(PropertyChanging != null) { PropertyChanging(this, new PropertyChangingEventArgs(propertyName)); } } private int _TableKey; [Column(IsPrimaryKey = true, IsDbGenerated = true, DbType = "INT NOT NULL Identity", CanBeNull = false, AutoSync = AutoSync.OnInsert)] public int TableKey { get { return _TableKey; } set { NotifyPropertyChanging("TableKey"); _TableKey = value; NotifyPropertyChanged("TableKey"); } } The last part of the database definition that needs to be created is the data context.  This is a simple class that takes an isolated storage location connection string its constructor and then instantiates tables as public properties. public class MyDataContext: DataContext{ public MyDataContext(string connectionString): base(connectionString) { MyRecords = this.GetTable<MyTable>(); } public Table<MyTable> MyRecords;} Creating A New Database Instance Now that we have a database definition it is time to create an instance of the data context within our Windows Phone app.  When your app fires up it should check if the database already exists and create an instance if it does not.  I would suggest that this be part of the constructor of your ViewModel. db = new MyDataContext(connectionString);if(!db.DatabaseExists()){ db.CreateDatabase();} The next thing you have to know is how the connection string for isolated storage should be constructed.  The main sticking point I have found is that the database cannot be created unless the file mode is read/write.  You may have different connection strings but the initial one needs to be similar to the following. string connString = "Data Source = 'isostore:/MyApp.sdf'; File Mode = read write"; Using you database Now that you have done all the up front work it is time to put the database to use.  To make your life a little easier and keep proper separation between your view and your viewmodel you should add a couple of methods to the viewmodel.  These will do the CRUD work of your application.  What you will notice is that the SubmitChanges method is the secret sauce in all of the methods that change data. private myDataContext myDb;private ObservableCollection<MyTable> _viewRecords;public ObservableCollection<MyTable> ViewRecords{ get { return _viewRecords; } set { _viewRecords = value; NotifyPropertyChanged("ViewRecords"); }}public void LoadMedstarDbData(){ var tempItems = from MyTable myRecord in myDb.LocalScans select myRecord; ViewRecords = new ObservableCollection<MyTable>(tempItems);}public void SaveChangesToDb(){ myDb.SubmitChanges();}public void AddMyTableItem(MyTable newScan){ myDb.LocalScans.InsertOnSubmit(newScan); myDb.SubmitChanges();}public void DeleteMyTableItem(MyTable newScan){ myDb.LocalScans.DeleteOnSubmit(newScan); myDb.SubmitChanges();} Updating existing database What happens when you need to change the structure of your database?  Unfortunately you have to add code to your application that checks the version of the database which over time will create some pollution in your codes base.  On the other hand it does give you control of the update.  In this example you will see the DatabaseSchemaUpdater in action.  Assuming we added a “Notes” field to the MyTable structure, the following code will check if the database is the latest version and add the field if it isn’t. if(!myDb.DatabaseExists()){ myDb.CreateDatabase();}else{ DatabaseSchemaUpdater dbUdater = myDb.CreateDatabaseSchemaUpdater(); if(dbUdater.DatabaseSchemaVersion < 2) { dbUdater.AddColumn<MyTable>("Notes"); dbUdater.DatabaseSchemaVersion = 2; dbUdater.Execute(); }} Summary This approach does take a fairly large amount of work, but I think the end product is robust and very native for .NET developers.  It turns out to be worth the investment. del.icio.us Tags: Windows Phone,Windows Phone 7,LINQ to SQL,LINQ,Database,Isolated Storage

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• Data Source Security Part 2

  - by Steve Felts

  In Part 1, I introduced the default security behavior and listed the various options available to change that behavior.  One of the key topics to understand is the difference between directly using database user and password values versus mapping from WLS user and password to the associated database values.   The direct use of database credentials is relatively new to WLS, based on customer feedback.  Some of the trade-offs are covered in this article. Credential Mapping vs. Database Credentials Each WLS data source has a credential map that is a mechanism used to map a key, in this case a WLS user, to security credentials (user and password).  By default, when a user and password are specified when getting a connection, they are treated as credentials for a WLS user, validated, and are converted to a database user and password using a credential map associated with the data source.  If a matching entry is not found in the credential map for the data source, then the user and password associated with the data source definition are used.  Because of this defaulting mechanism, you should be careful what permissions are granted to the default user.  Alternatively, you can define an invalid default user to ensure that no one can accidentally get through (in this case, you would need to set the initial capacity for the pool to zero so that the pool is populated only by valid users). To create an entry in the credential map: 1) First create a WLS user.  In the administration console, go to Security realms, select your realm (e.g., myrealm), select Users, and select New.  2) Second, create the mapping.  In the administration console, go to Services, select Data sources, select your data source name, select Security, select Credentials, and select New.  See http://docs.oracle.com/cd/E24329_01/apirefs.1211/e24401/taskhelp/jdbc/jdbc_datasources/ConfigureCredentialMappingForADataSource.html for more information. The advantages of using the credential mapping are that: 1) You don’t hard-code the database user/password into a program or need to prompt for it in addition to the WLS user/password and 2) It provides a layer of abstraction between WLS security and database settings such that many WLS identities can be mapped to a smaller set of DB identities, thereby only requiring middle-tier configuration updates when WLS users are added/removed. You can cut down the number of users that have access to a data source to reduce the user maintenance overhead.  For example, suppose that a servlet has the one pre-defined, special WLS user/password for data source access, hard-wired in its code in a getConnection(user, password) call.  Every WebLogic user can reap the specific DBMS access coded into the servlet, but none has to have general access to the data source.  For instance, there may be a ‘Sales’ DBMS which needs to be protected from unauthorized eyes, but it contains some day-to-day data that everyone needs. The Sales data source is configured with restricted access and a servlet is built that hard-wires the specific data source access credentials in its connection request.  It uses that connection to deliver only the generally needed day-to-day information to any caller. The servlet cannot reveal any other data, and no WebLogic user can get any other access to the data source.  This is the approach that many large applications take and is the reasoning behind the default mapping behavior in WLS. The disadvantages of using the credential map are that: 1) It is difficult to manage (create, update, delete) with a large number of users; it is possible to use WLST scripts or a custom JMX client utility to manage credential map entries. 2) You can’t share a credential map between data sources so they must be duplicated. Some applications prefer not to use the credential map.  Instead, the credentials passed to getConnection(user, password) should be treated as database credentials and used to authenticate with the database for the connection, avoiding going through the credential map.  This is enabled by setting the “use-database-credentials” to true.  See http://docs.oracle.com/cd/E24329_01/apirefs.1211/e24401/taskhelp/jdbc/jdbc_datasources/ConfigureOracleParameters.html "Configure Oracle parameters" in Oracle WebLogic Server Administration Console Help. Use Database Credentials is not currently supported for Multi Data Source configurations.  When enabled, it turns off credential mapping on Generic and Active GridLink data sources for the following attributes: 1. identity-based-connection-pooling-enabled (this interaction is available by patch in 10.3.6.0). 2. oracle-proxy-session (this interaction is first available in 10.3.6.0). 3. set client identifier (this interaction is available by patch in 10.3.6.0).  Note that in the data source schema, the set client identifier feature is poorly named “credential-mapping-enabled”.  The documentation and the console refer to it as Set Client Identifier. To review the behavior of credential mapping and using database credentials: - If using the credential map, there needs to be a mapping for each WLS user to database user for those users that will have access to the database; otherwise the default user for the data source will be used.  If you always specify a user/password when getting a connection, you only need credential map entries for those specific users. - If using database credentials without specifying a user/password, the default user and password in the data source descriptor are always used.  If you specify a user/password when getting a connection, that user will be used for the credentials.  WLS users are not involved at all in the data source connection process.

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• In 3D camera math, calculate what Z depth is pixel unity for a given FOV

  - by badweasel

  I am working in iOS and OpenGL ES 2.0. Through trial and error I've figured out a frustum to where at a specific z depth pixels drawn are 1 to 1 with my source textures. So 1 pixel in my texture is 1 pixel on the screen. For 2d games this is good. Of course it means that I also factor in things like the size of the quad and the size of the texture. For example if my sprite is a quad 32x32 pixels. The quad size is 3.2 units wide and tall. And the texcoords are 32 / the size of the texture wide and tall. Then the frustum is: matrixFrustum(-(float)backingWidth/frustumScale,(float)backingWidth/frustumScale, -(float)backingHeight/frustumScale, (float)backingHeight/frustumScale, 40, 1000, mProjection); Where frustumScale is 800 for a retina screen. Then at a distance of 800 from camera the sprite is pixel for pixel the same as photoshop. For 3d games sometimes I still want to be able to do this. But depending on the scene I sometimes need the FOV to be different things. I'm looking for a way to figure out what Z depth will achieve this same pixel unity for a given FOV. For this my mProjection is set using: matrixPerspective(cameraFOV, near, far, (float)backingWidth / (float)backingHeight, mProjection); With testing I found that at an FOV of 45.0 a Z of 38.5 is very close to pixel unity. And at an FOV of 30.0 a Z of 59.5 is about right. But how can I calculate a value that is spot on? Here's my matrixPerspecitve code: void matrixPerspective(float angle, float near, float far, float aspect, mat4 m) { //float size = near * tanf(angle / 360.0 * M_PI); float size = near * tanf(degreesToRadians(angle) / 2.0); float left = -size, right = size, bottom = -size / aspect, top = size / aspect; // Unused values in perspective formula. m[1] = m[2] = m[3] = m[4] = 0; m[6] = m[7] = m[12] = m[13] = m[15] = 0; // Perspective formula. m[0] = 2 * near / (right - left); m[5] = 2 * near / (top - bottom); m[8] = (right + left) / (right - left); m[9] = (top + bottom) / (top - bottom); m[10] = -(far + near) / (far - near); m[11] = -1; m[14] = -(2 * far * near) / (far - near); } And my mView is set using: lookAtMatrix(cameraPos, camLookAt, camUpVector, mView); * UPDATE * I'm going to leave this here in case anyone has a different solution, can explain how they do it, or why this works. This is what I figured out. In my system I use a 10th scale unit to pixels on non-retina displays and a 20th scale on retina displays. The iPhone is 640 pixels wide on retina and 320 pixels wide on non-retina (obsolete). So if I want something to be the full screen width I divide by 20 to get the OpenGL unit width. Then divide that by 2 to get the left and right unit position. Something 32 units wide centered on the screen goes from -16 to +16. Believe it or not I have an excel spreadsheet do all this math for me and output all the vertex data for my sprite sheet. It's an arbitrary thing I made up to do .1 units = 1 non-retina pixel or 2 retina pixels. I could have made it .01 units = 2 pixels and someday I might switch to that. But for now it's the other. So the width of the screen in units is 32.0, and that means the left most pixel is at -16.0 and the right most is at 16.0. After messing a bit I figured out that if I take the [0] value of an identity modelViewProjection matrix and multiply it by 16 I get the depth required to get 1:1 pixels. I don't know why. I don't know if the 16 is related to the screen size or just a lucky guess. But I did a test where I placed a sprite at that calculated depth and varied the FOV through all the valid values and the object stays steady on screen with 1:1 pixels. So now I'm just calculating the unityDepth that way. If someone gives me a better answer I'll checkmark it.

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• ExplorerCanvas and JQuery

  - by PhubarBaz

  I am working on a Javascript app (CloudGraph) that uses HTML5 canvas and JQuery. I'm using ExplorerCanvas to support canvas in IE. I recently came across an interesting problem. What I was trying to do is restore the user's settings when the page is loaded. I read some information from a cookie that I set the last time the user accessed the application. One of these settings is the size of the canvas. I decided that the best place to do this would be when the document is ready using JQuery $(document).ready(). This worked fine in browsers that natively support the canvas element. But in IE it kept getting errors the first time I would hit the page. It seemed that the excanvas element wasn't initialized yet because I was getting null reference and unknown properties errors. If I refreshed the page the errors went away but the resized canvas wasn't drawing on the entire area of the canvas. It was like the clipping rectangle was still set to the default canvas size. I found that the canvas element when using excanvas has a div child element which is where the actual drawing takes place. When I changed the width and height of the canvas element in document.ready it didn't change the width and height of the child div. Initially my solution was to also change the div element when changing the canvas element and that worked. But then I realized that having to refresh the page every time I started the app in IE really sucked. That wouldn't be acceptable for users. Since it seemed like the canvas wasn't getting initialized before I was trying to use it I decided to try to initialize my app at a different time. I figured the next best place was in the onload event. Sure enough, moving my initialization to onload fixed all of the problems. So, it looks like the canvas shouldn't be manipulated until the onload event when using ExplorerCanvas. There might be ways to do it when the document is ready. I found some posts on initializing excanvas manually, but for me waiting until onload worked just fine.

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• Silverlight 4 Twitter Client &ndash; Part 5

  - by Max

  In this post, we will look at implementing the following in our twitter client - displaying the profile picture in the home page after logging in. So to accomplish this, we will need to do the following steps. 1) First of all, let us create another field in our Global variable static class to hold the profile image url. So just create a static string field in that. public static string profileImage { get; set; } 2) In the Login.xaml.cs file, before the line where we redirect to the Home page if the login was successful. Create another WebClient request to fetch details from this url - .xml">http://api.twitter.com/1/users/show/<TwitterUsername>.xml I am interested only in the “profile_image_url” node in this xml string returned. You can choose what ever field you need – the reference to the Twitter API Documentation is here. 3) This particular url does not require any authentication so no need of network credentials for this and also the useDefaultCredentials will be true. So this code would look like. WebRequest.RegisterPrefix("http://", System.Net.Browser.WebRequestCreator.ClientHttp); WebClient myService = new WebClient(); myService.AllowReadStreamBuffering = myService.UseDefaultCredentials = true; myService.DownloadStringCompleted += new DownloadStringCompletedEventHandler(TimelineRequestCompleted_User);) myService.DownloadStringAsync(new Uri("http://api.twitter.com/1/users/show/" + TwitterUsername.Text + ".xml")); 4) To parse the xml file returned by this and get the value of the “profile_image_url” node, the LINQ code will look something like XDocument xdoc; xdoc = XDocument.Parse(e.Result); var answer = (from status in xdoc.Descendants("user") select status.Element("profile_image_url").Value); GlobalVariable.profileImage = answer.First().ToString(); 5) After this, we can then redirect to Home page completing our login formalities. 6) In the home page, add a image tag and give it a name, something like <Image Name="image1" Stretch="Fill" Margin="29,29,0,0" Height="73" VerticalAlignment="Top" HorizontalAlignment="Left" Width="73" /> 7) In the OnNavigated to event in home page, we can set the image source url as below image1.Source = new BitmapImage(new Uri(GlobalVariable.profileImage, UriKind.Absolute)); Hope this helps. If you have any queries / suggestions, please feel free to comment below or contact me. Technorati Tags: Silverlight,LINQ,Twitter API,Twitter

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• How can I improve the battery life under 12.04 on my Inspiron 14z? [duplicate]

  - by cfogelberg

  This question already has an answer here: Tips to extend battery life for laptops and notebooks 24 answers How do I improve the battery life of my Inspiron 14z under Ubuntu 12.04? This laptop gets 4-5 hours of battery life using Windows (e.g. here). I've removed Windows, installed Ubuntu 12.04 and the initial battery life was only 2 hours. With some tweaks (described below) it's still only ~2.5 hours. For reference, the laptop is the latest model of the 14z: i5-3337U processor 32GB MSATA, 500GB HDD (5400rpm) AMD Radeon HD7570M graphics card I have put ext4 partitions on both the SSD and the HDD, and have mounted / to the SSD and /home to the HDD. I also put a 24gb linux swap partition at the start of the HDD, though I figure this won't be used all that much (the laptop has 8gb of RAM). After googling around and reading Ask Ubuntu and other sites extensively, I have done the following steps, and they have improved the battery life ~30 minutes (exact improvement not clear, but battery life is still nowhere near 4-5 hours). Installed Jupiter (and set Performance to "Power Saving") Installed laptop-mode-tools cat /proc/sys/vm/laptop_mode now outputs 5 (previously it output 0) But it's not clear that this will help: AskUbuntu question Turned down the brightness of my screen from full to 1/3 Other things I have heard about but have not tried for fear of frying the laptop or my linux install: Add "pcie_aspm=force" at the end of the line with "quiet splash" in /boot/grub/grub.cfg Enable ALPM, but it may already be enabled in 12.04? Enable i915 framebuffer compression Use a propietary driver for the graphics card? Turn off the graphics card? (what would happen if I relied on the internal Intel bridge?) Use TLP? Spin down the HDD more aggressively (howto, but I think laptop-mode-tools does this already) The only other thing I've noticed is that plastic just above the F5, F6 and F7 keys gets really hot. According to Jupiter my CPU temperature is only 69 celsius and the System Monitor shows CPU load at 7% so I don't think it's the CPU. Maybe it's the graphics card? Also, I've set up MongoDB and LAMP on the machine as well. When I run powertop MongoDB is high in the list, but I'm not sure if that's relevant to battery life because I'm not actually doing anything with MongoDB most of the time. Edit - Additional info as requested $ lspci -nnk | grep -iEA3 "(graphics|vga)" 00:02.0 VGA compatible controller [0300]: Intel Corporation Ivy Bridge Graphics Controller [8086:0166] (rev 09) Subsystem: Dell Device [1028:057f] Kernel driver in use: i915 Kernel modules: i915 -- 02:00.0 VGA compatible controller [0300]: Advanced Micro Devices [AMD] nee ATI Thames [Radeon 7500M/7600M Series] [1002:6841] Subsystem: Dell Device [1028:057f] Kernel driver in use: radeon Kernel modules: radeon

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• Physics Engine [Collision Response, 2-dimensional] experts, help!! My stack is unstable!

  - by Register Sole

  Previously, I struggle with the sequential impulse-based method I developed. Thanks to jedediah referring me to this paper, I managed to rebuild the codes and implement the simultaneous impulse based method with Projected-Gauss-Seidel (PGS) iterative solver as described by Erin Catto (mentioned in the reference of the paper as [Catt05]). So here's how it currently is: The simulation handles 2-dimensional rotating convex polygons. Detection is using separating-axis test, with a SKIN, meaning closest points between two polygons is detected and determined if their distance is less than SKIN. To resolve collision, simultaneous impulse-based method is used. It is solved using iterative solver (PGS-solver) as in Erin Catto's paper. Error-correction is implemented using Baumgarte's stabilization (you can refer to either paper for this) using J V = beta/dt*overlap, J is the Jacobian for the constraints, V the matrix containing the velocities of the bodies, beta an error-correction parameter that is better be < 1, dt the time-step taken by the engine, and overlap, the overlap between the bodies (true overlap, so SKIN is ignored). However, it is still less stable than I expected :s I tried to stack hexagons (or squares, doesn't really matter), and even with only 4 to 5 of them, they hardly stand still! Also note that I am not looking for a sleeping scheme. But I would settle if you have any explicit scheme to handle resting contacts. That said, I would be more than happy if you have a way of treating it generally (as continuous collision, instead of explicitly as a special state). Ideas I have: I would try adding a damping term (proportional to velocity) to the Baumgarte. Is this a good idea in general? If not I would not want to waste my time trying to tune the parameter hoping it magically works. Ideas I have tried: Using simultaneous position based error correction as described in the paper in section 5.3.2, turned out to be worse than the current scheme. If you want to know the parameters I used: Hexagons, side 50 (pixels) gravity 2400 (pixels/sec^2) time-step 1/60 (sec) beta 0.1 restitution 0 to 0.2 coeff. of friction 0.2 PGS iteration 10 initial separation 10 (pixels) mass 1 (unit is irrelevant for now, i modified velocity directly<-impulse method) inertia 1/1000 Thanks in advance! I really appreciate any help from you guys!! :)

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• JDK 8u20 Documentation Updates

  - by joni g.

  JDK 8u20 has been released and is available from the Java Downloads page. See the JDK 8u20 Update Release Notes for details. Highlights for this release: The Medium security level has been removed. Now only High and Very High levels are available. Applets that do not conform with the latest security practices can still be authorized to run by adding the sites that host them to the Exception Site List. See Security for more information. The javafxpackager tool has been renamed to javapackager, and supports both Java and JavaFX applications. The -B option has been added to the javapackager deploy command to enable arguments to be passed to the bundlers that are used to create self-contained applications. See javapackager for Windows or Linux and OS X for information. The <fx:bundleArgument> helper parameter argument has been added to enable arguments to be passed to the bundlers when using ant tasks. See JavaFX Ant Task Reference for more information. A new attribute is available for JAR file manifests. The Entry-Point attribute is used to identify the classes that are allowed to be used as entry points to your application. See Entry-Point Attribute for more information. A new Microsoft Windows Installer (MSI) Enterprise JRE Installer, which enables users to install the JRE across the enterprise, is available for Java SE Advanced or Java SE Suite licensees. See Downloading the Installer in JRE Installation For Microsoft Windows for more information. The following new configuration parameters are added to the installation process to support commercial features, for use by Java SE Advanced or Java SE Suite licensees only: USAGETRACKERCFG= DEPLOYMENT_RULE_SET= See Installing With a Configuration File for more information about these and other installer parameters. Documentation highlights: New Troubleshooting Guide combines and replaces the Desktop Technologies Troubleshooting Guide and the HotSpot Virtual Machine Troubleshooting Guide to provide a single location for diagnosing and solving problems that might occur with Java Client applications. New Deployment Guide combines and replaces the JavaFX Deployment Guide and the Java Rich Internet Applications Guide to provide a single location for information about the Java packaging tools, creating self-contained applications, and deploying Java and JavaFX applications. New Garbage Collection Tuning Guide describes the garbage collectors included with the Java HotSpot VM and helps you choose which one to use. The Java Tutorials have a new look.

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• How to chain actions/animations together and delay their execution?

  - by codinghands

  I'm trying to build a simple game with a number of screens - 'TitleScreen', 'LoadingScreen', 'PlayScreen', 'HighScoreScreen' - each of which has it's own draw & update logic methods, sprites, other useful fields, etc. This works well for me as a game dev beginner, and it runs. However, on my 'PlayScreen' I want to run some animations before the player gets control - dropping in some artwork, playing some sound effects, generally prettifying things a little. However, I'm not sure what the best way to chain animations / sound effects / other timed general events is. I could make an intermediary screen, 'PrePlayScreen', which simply has all of this hardcoded like so: Update(){ Animation anim1 = new Animation(.....); Animation anim2 = new Animation(.....); anim1.Run(); if(anim1.State == AnimationState.Complete) anim2.Run(); if(anim2.State == AnimationState.Complete) // Load 'PlayScreen' screen } But this doesn't seem so great - surely their must be a better way? I then thought, 'Hey - an AnimationManager! That'd be awesome!'. But then that creeping OOP panic set in as I thought about it some more. If I create the Animation in my Screen, then add it to the AnimationManager (which may or may not be a GameComponent hooked up to Update/Draw), how can I get 'back' to it? To signal commands like start / end / repeat? I'd still need to keep a reference to the object in my Screen so that I could still communicate with it once it's buried in the bosom of a List in my AnimationManager. This seems bad. I've also tried using events - call 'Update' on all the animations in the PlayScreen update loop, but crucially all of the animations have a bool flag ('Active') which determines whether they should begin. The first animation has this set to 'true', all others 'false'. On completion the first animation raises an event, which sets animation 2's bool flag to true (and so it then runs). Once animation 2 is complete another 'anim complete' event is raised, and the screen state changes. Considering the game I'm making is basically as simple as it gets I know I'm overthinking this... it's just the paradigm shift from web - game development is making me break out in a serious case of the stupids.

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• Flattening System.Web.UI ControlCollection

  - by evovision

  Hi,   Sometimes one may need to get a list of child controls inside specific container and don't care about the underlying hierarchy.   The result is beautifully achieved using this extension method:   using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;    public static class ControlCollectionExtensionMethods    {        public static IEnumerable<Control> FlattenedList(this ControlCollection controls)        {            foreach (Control ctrl in controls)            {                  // return parent control                   yield return ctrl;                              // and dive into child collection                   foreach (Control child in ctrl.Controls.FlattenedList())                         yield return child;            }        }    }   P.S.: don't forget about namespaces when using it in your code, if above class is wrapped into namespace, for example: Sample, the source code file with calling code must explicitly reference it: using Sample;

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