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  • The performance implications of IEnumerable vs. IQueryable

    It all started innocently enough. I was implementing a "Older Posts/Newer Posts" feature for my new web site and was writing code like this:IEnumerable<Post> FilterByCategory(IEnumerable<Post> posts, string category) {  if( !string.IsNullOrEmpty(category) ) { return posts.Where(p => p.Category.Contains(category)); }}...  var posts = FilterByCategory(db.Posts, category);  int count = posts.Count();... The "db" was an EF object context object, but it could just as...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • The performance implications of IEnumerable vs. IQueryable

    It all started innocently enough. I was implementing a "Older Posts/Newer Posts" feature for my new web site and was writing code like this:IEnumerable<Post> FilterByCategory(IEnumerable<Post> posts, string category) {  if( !string.IsNullOrEmpty(category) ) { return posts.Where(p => p.Category.Contains(category)); }}...  var posts = FilterByCategory(db.Posts, category);  int count = posts.Count();... The "db" was an EF object context object, but it could just as...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Identify "non-secure" content IE warns about [on hold]

    - by Doug Harris
    As many know, if you serve a page over https and the content loads resources (images, stylesheets, js, SWF objects, etc) over http, older versions of Internet Explorer will show the user a warning saying "This page contains both secure and non-secure items". This is discomforting to many non-technical users. Usually, I can look at the HTML source and identify which item(s) are triggering this error. Sometimes a Flash object will load something else or some embedded javascript will put a new object in the DOM and trigger this. What tools are good for quickly tracking down the source of the warning?

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  • Equation / formula to determine an objects position on an ellipitcal path

    - by David Murphy
    I'm making a space game, as such I need objects to follow an elliptical path (orbit). I've worked out how to calculate all the important aspects of my orbits, the only remaining thing is how to have an object follow it. My Orbit class contains the major, minor (and by extension semi-major,semi-minor) lengths. The focii radius, area and circumference even. What is the equation to determine an objects x/y position (only need 2D) on an ellipse with a certain speed after a period of time. Basically, every frame I want to update the position based on the amount of elapsed time. I would like to have the speed along the path speed up and slow down according to the distance from the object it's orbiting, but not sure how to factor this in to the above given that at any point in time the speed has changed from it's previous speed. EDIT I can't answer my own question. But I found the question and answer is already on stackexchange: Kepler orbit : get position on the orbit over time

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  • HTML5 - check if font has loaded

    - by espais
    At present I load my font for my game in with @font-face For instance: @font-face { font-family: 'Orbitron'; src: url('res/orbitron-medium.ttf'); } and then reference it throughout my JS implementation as such: ctx.font = "12pt Orbitron"; where ctx is my 2d context from the canvas. However, I notice a certain lag time while the font is downloaded to the user. Is there a way I can use a default font until it is loaded in?

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  • Securing the Tabular BI Semantic Model

    This paper introduces the security model for tabular BI semantic models in SQL Server 2012. You will learn how to create roles, implement dynamic security, configure impersonation settings, manage roles, and choose a method for connecting to models that works in your network security context. New! SQL Monitor 3.0 Red Gate's multi-server performance monitoring and alerting tool gets results from Day One.Simple to install and easy to use – download a free trial today.

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  • Using Instance Nodes, worth it?

    - by Twitch
    I am making a 2d game where there are various environments with lots and lots of objects. There is a forest scene with like 1200 objects in total(trees mainly), of which around 100 are visible on the camera at any given time, as you move through the level. These are comprised of around 20 different kind of trees and other props. Each object is usually 2-6 triangles with a transparent texture. My developer asked me to replace each object in the scene with a node, and keeping only a minimal amount of actual objects which would be 300+ or so(?), since there are a few modified unique meshes. So he can instantiate the actual objects to keep the game light. Is this actually effective? And if so how much? I 've read about draw calls and such and I suppose that if I combine each texture (10 kinds of trees) in 1 mesh it will have the same effect?

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  • Making a collision detection system

    - by Sri Harsha Chilakapati
    I'm very new to game development (just started 3 months ago) and I've learning through creating a game engine. It's located here. In terms of collision, I know only brutefoce detection, in which case, the game slows down if there are a number of objects. So my question is How should I program the collisions? I want them to happen automatically for every object and call the object's collision(GObject other) method on each collision. Are there any new algorithms which can make this fast? If so, can anybody6 sh6ed some light on this topic? And I think of making it like the game maker Thanks

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  • Manual memory allocation and purity

    - by Eonil
    Language like Haskell have concept of purity. In pure function, I can't mutate any state globally. Anyway Haskell fully abstracts memory management, so memory allocation is not a problem here. But if languages can handle memory directly like C++, it's very ambiguous to me. In these languages, memory allocation makes visible mutation. But if I treat making new object as impure action, actually, almost nothing can be pure. So purity concept becomes almost useless. How should I handle purity in languages have memory as visible global object?

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  • What is going on in this SAT/vector projection code?

    - by ssb
    I'm looking at the example XNA SAT collision code presented here: http://www.xnadevelopment.com/tutorials/rotatedrectanglecollisions/rotatedrectanglecollisions.shtml See the following code: private int GenerateScalar(Vector2 theRectangleCorner, Vector2 theAxis) { //Using the formula for Vector projection. Take the corner being passed in //and project it onto the given Axis float aNumerator = (theRectangleCorner.X * theAxis.X) + (theRectangleCorner.Y * theAxis.Y); float aDenominator = (theAxis.X * theAxis.X) + (theAxis.Y * theAxis.Y); float aDivisionResult = aNumerator / aDenominator; Vector2 aCornerProjected = new Vector2(aDivisionResult * theAxis.X, aDivisionResult * theAxis.Y); //Now that we have our projected Vector, calculate a scalar of that projection //that can be used to more easily do comparisons float aScalar = (theAxis.X * aCornerProjected.X) + (theAxis.Y * aCornerProjected.Y); return (int)aScalar; } I think the problems I'm having with this come mostly from translating physics concepts into data structures. For example, earlier in the code there is a calculation of the axes to be used, and these are stored as Vector2, and they are found by subtracting one point from another, however these points are also stored as Vector2s. So are the axes being stored as slopes in a single Vector2? Next, what exactly does the Vector2 produced by the vector projection code represent? That is, I know it represents the projected vector, but as it pertains to a Vector2, what does this represent? A point on a line? Finally, what does the scalar at the end actually represent? It's fine to tell me that you're getting a scalar value of the projected vector, but none of the information I can find online seems to tell me about a scalar of a vector as it's used in this context. I don't see angles or magnitudes with these vectors so I'm a little disoriented when it comes to thinking in terms of physics. If this final scalar calculation is just a dot product, how is that directly applicable to SAT from here on? Is this what I use to calculate maximum/minimum values for overlap? I guess I'm just having trouble figuring out exactly what the dot product is representing in this particular context. Clearly I'm not quite up to date on my elementary physics, but any explanations would be greatly appreciated.

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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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  • Do programmers have a higher IQ? [closed]

    - by Laurent Pireyn
    Do programmers have a higher intellectual quotient than the average 100? Has anybody conducted studies on that topic? Don't get me wrong! I consider IQ as a limited measure that only evaluates the analytical part of one's intelligence. Furthermore, I think that intelligence is only one among many characteristics, and that it should not be used to judge or discriminate people. My question should be read in that context.

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  • What Design Pattern is seperating transform converters

    - by RevMoon
    For converting a Java object model into XML I am using the following design: For different types of objects (e.g. primitive types, collections, null, etc.) I define each its own converter, which acts appropriate with respect to the given type. This way it can easily extended without adding code to a huge if-else-then construct. The converters are chosen by a method which tests whether the object is convertable at all and by using a priority ordering. The priority ordering is important so let's say a List is not converted by the POJO converter, even though it is convertable as such it would be more appropriate to use the collection converter. What design pattern is that? I can only think of a similarity to the command pattern.

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  • Is the escaping provided by the Google-Gson library enough to ensure a safe JSON payload?

    - by Lifetime_Learner
    I am currently using the Google-Gson library to convert Java objects into JSON inside a web service. Once the object has been converted to JSON, it is returned to the client to be converted into a JSON object using the JavaScript eval() function. Is the character escaping provided by the Gson library enough to ensure that nothing nasty will happen when I run the eval() function on the JSON payload? Do I need to HTML Encode the Strings in the Java Objects before passing them to the Gson library? Are there any other security concerns that I should be aware of?

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  • Adding a small slide when player releases left/right key

    - by Dave
    the aim is for the player object to slow down and stop instead of just stopping dead. The following codes works ok when the player is not jumping, but gets stuck in an object if the player is in the air when they do it. Left Key released event: if hsp = 0 exit; hspeed = -3; friction = 0.20; if obj_Player.hspeed = 0 { hspeed = 0; } Right key released event: if hsp = 0 exit; hspeed = +3; friction = 0.20; if obj_Player.hspeed = 0 { hspeed = 0; } and here's the horizontal collision code for interest: if (place_meeting(x+hsp,y,obj_bound)) { while(!place_meeting(x+sign(hsp),y,obj_bound)) { x += sign(hsp); } hsp = 0; } x += hsp; Any help would be much appreciated. Thanks.

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  • Should I use the factory design pattern for every class?

    - by Frog
    I've been writing a website in PHP. As the code becomes more complex, I keep finding problems that can be solved using the factory design pattern. For example: I've a got a class Page which has subclasses HTMLPage, XMLPage, etc. Depending on some input I need to return an object of either one of these classes. I use the factory design pattern to do this. But as I encounter this problem in more classes, I keep having to change code which still initiates an object using its constructor. So now I'm wondering: is it a good idea to change all code so that it uses the factory design pattern? Or are there big drawbacks? I'm currently in a position to change this, so your answers would be really helpful.

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  • Is there a name for this use of the State design pattern?

    - by Chris C
    I'm looking to see if there is a particular name for this style of programming a certain kind of behavior into a program. Said program runs in real time, in an update loop, and the program uses the State design pattern to do some work, but it's the specific way it does the work that I want to know about. Here's how it's used. - Object Foo constructed, with concrete StateA object in it - First loop runs --- Foo.Run function calls StateA.Bar --- in StateA.Bar replace Foo's state to StateB - Second loop runs --- Foo.Run calls StateB.Bar - Third loop runs --- Foo.Run calls StateB.Bar - Fourth loop --- etc. So in short, Foo doesn't have an explicit Initialize function. It will just have Run, but Run will do something unique in the first frame to initialize something for Foo and then replace it with a different action that will repeat in all the frames following it- thus not needing to check if Foo's already initialized. It's just a "press start and go" action. What would you call implementing this type of behavior?

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  • Are these non-standard applications of rendering practical in games?

    - by maul
    I've recently got into 3D and I came up with a few different "tricky" rendering techniques. Unfortunately I don't have the time to work on this myself, but I'd like to know if these are known methods and if they can be used in practice. Hybrid rendering Now I know that ray-tracing is still not fast enough for real-time rendering, at least on home computers. I also know that hybrid rendering (a combination of rasterization and ray-tracing) is a well known theory. However I had the following idea: one could separate a scene into "important" and "not important" objects. First you render the "not important" objects using traditional rasterization. In this pass you also render the "important" objects using a special shader that simply marks these parts on the image using a special color, or some stencil/depth buffer trickery. Then in the second pass you read back the results of the first pass and start ray tracing, but only from the pixels that were marked by the "important" object's shader. This would allow you to only ray-trace exactly what you need to. Could this be fast enough for real-time effects? Rendered physics I'm specifically talking about bullet physics - intersection of a very small object (point/bullet) that travels across a straight line with other, relatively slow-moving, fairly constant objects. More specifically: hit detection. My idea is that you could render the scene from the point of view of the gun (or the bullet). Every object in the scene would draw a different color. You only need to render a 1x1 pixel window - the center of the screen (again, from the gun's point of view). Then you simply check that central pixel and the color tells you what you hit. This is pixel-perfect hit detection based on the graphical representation of objects, which is not common in games. Afaik traditional OpenGL "picking" is a similar method. This could be extended in a few ways: For larger (non-bullet) objects you render a larger portion of the screen. If you put a special-colored plane in the middle of the scene (exactly where the bullet will be after the current frame) you get a method that works as the traditional slow-moving iterative physics test as well. You could simulate objects that the bullet can pass through (with decreased velocity) using alpha blending or some similar trick. So are these techniques in use anywhere, and/or are they practical at all?

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  • Ubuntu ONE (Windows BETA) locks up - What to do?

    - by Zusch
    OS: Windows XP SP3 Hardware: Dell Precision M4400 (Laptop) CPU: Core2Duo T9600 Mem: 4 GB Installer- setup, first start and account- setup of UbuntuONE Windows client passed with no problems. After restart of UbuntuONE, the CPU- usage shows 50% (100% core usage). Exit- command (from context-menu) hides the trayicon, but the program is still working excessive in background (50% cpu- / 50 MB memory- usage), until UbuntuOneClient.exe is killed by the taskmanager. What's going on ?

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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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  • How do I succesfully compile Slingshot?

    - by Tigull
    I've been trying to compile Slingshot for a preview of Elementary OS. Even after replacing Gtk.Stock.CLEAR and Gtk.Stock.add with Gtk.STOCK_CLEAR and Gtk.Stock_add in slingshot/widget/entries .vala I still get the following error when executing sudo ./build_run: frontend/widgets/Entries.vala:130.13-130.25: error: The name `Stock_add' does not exist in the context of `Gtk' Gtk.Stock_add ({stock_item}); ^^^^^^^^^^^^^ Compilation failed: 1 error(s), 0 warning(s) mv: cannot stat `slingshot': No such file or directory ./build_run: 7: slingshot: not found I haven't found yet a soulution, therefore any help is appreciated, thanks!

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  • XNA Monogame GameState Management not deserilaizing

    - by Pectus Excavatum
    I am having some trouble serializing/deserializing in a little game I am doing to teach myself monogame. Basically, I am using the gamestatemnanagement resources common to monogame (screen manager etc). Then I am serializing my screen manager component and all associated screens in the OnDeactivated method: protected override void OnDeactivated(Object sender, EventArgs args) { foreach (GameplayScreen screen in mScreenManager.GetScreens()) { DataManager.SaveData(screen.Level.LevelData); } mScreenManager.SerializeState(); } The Save data bit is to do with something else. Then I then override OnActivated to de serialize protected override void OnActivated(Object sender, EventArgs args) { //System.Diagnostics.Debug.WriteLine("here activating"); mScreenManager.DeserializeState(); } However, when this runs it just loads a blank screen - it goes into the game initialize and the game draw method, but doesnt go down into the screens initialize or draw methods. I have no idea why this might be - any help would be greatly appreciated. I am not the only one who has encountered this - I found this post also - https://monogame.codeplex.com/discussions/391117

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  • Houston We have a Problem with Silverlight Client OM&hellip;

    - by MOSSLover
    So I was playing around with NavigationNodeCollection, which is basically like SPNavigationNodeCollection just to make sure it worked without a hitch…Here is a little sample snippet of what should work: Unfortunately, you get a nice little javascript error that does not allow you to access the child nodes.  I tried a foreach() loop that gets a NavigationNode for each parent then loops through the NavigationNode.Children that did not work either.  I threw in two ExecuteQueryAsync statements thinking that would help, unfortunately adding a second statement provides no different results.  This appears to be a bug in the Silverlight Client Object Model.  I reported the error.  Hopefully, we get a fix by RTM so that we can use the easier method to get items into Silverlight, otherwise it’s back to WCF and cross domain policies.  We all love cross domain policies right? Technorati Tags: Client Object Model,SharePoint 2010,Silverlight

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