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  • Questions about identifying the components in MVC

    - by luiscubal
    I'm currently developing an client-server application in node.js, Express, mustache and MySQL. However, I believe this question should be mostly language and framework agnostic. This is the first time I'm doing a real MVC application and I'm having trouble deciding exactly what means each component. (I've done web applications that could perhaps be called MVC before, but I wouldn't confidently refer to them as such) I have a server.js that ties the whole application together. It does initialization of all other components (including the database connection, and what I think are the "models" and the "views"), receiving HTTP requests and deciding which "views" to use. Does this mean that my server.js file is the controller? Or am I mixing code that doesn't belong there? What components should I break the server.js file into? Some examples of code that's in the server.js file: var connection = mysql.createConnection({ host : 'localhost', user : 'root', password : 'sqlrevenge', database : 'blog' }); //... app.get("/login", function (req, res) { //Function handles a GET request for login forms if (process.env.NODE_ENV == 'DEVELOPMENT') { mu.clearCache(); } session.session_from_request(connection, req, function (err, session) { if (err) { console.log('index.js session error', err); session = null; } login_view.html(res, user_model, post_model, session, mu); //I named my view functions "html" for the case I might want to add other output types (such as a JSON API), or should I opt for completely separate views then? }); }); I have another file that belongs named session.js. It receives a cookies object, reads the stored data to decide if it's a valid user session or not. It also includes a function named login that does change the value of cookies. First, I thought it would be part of the controller, since it kind of dealt with user input and supplied data to the models. Then, I thought that maybe it was a model since it dealt with the application data/database and the data it supplies is used by views. Now, I'm even wondering if it could be considered a View, since it outputs data (cookies are part of HTTP headers, which are output)

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  • Oracle JDeveloper 11gR2 Cookbook book review

    - by Chris Muir
    I recently received a free copy of Oracle JDeveloper 11gR2 Cookbook published by Packt Publishing for review. Readers of technical cookbooks would know this genre of text includes problems that developers will hit and the prescribed solutions, in this case for Oracle's Application Development Framework (ADF).  Books like this excel themselves on excellent coverage, a logical progress of solutions through out the book, and providing a readable narrative around the numerous steps and code. This book progresses well through ADF application assembly, ADF Business Components, the view layer, security, deployment and tuning.  Each recipe had a clear introduction and I especially enjoyed the "There's more" follow up sections for some recipes that leads the reader onto related ideas and issues the reader really needs to be aware of. Also worthy of comment having worked with ADF for over 5 years, there certainly was recipes and solutions I hadn't encountered before, this book gets bonus points for that. As a reviewer what negatives can I give this text? The book has cast it's net too wide by trying to cover "everything from design and construction, to deployment, testing, debugging and optimization."  ADF is such a large and sophistication technology, this book with 100 recipes barely scrapes the surface.  Don't expect all your ADF problems to be solved here. In turn there is inconsistency in the level of problems and solutions.  I felt at the beginning the book was pitching itself at advanced problems to solve (that's great for me), but then it introduces topics like building a static View Object or train.  These topics in my opinion are fairly simple and are covered by the Oracle documentation just as well, they shouldn't have been included here.  In conclusion, ADF beginners will find this book worthwhile as it will open your eyes to the wider problems and solutions required for ADF, and experts for just the fact they can point junior programmers at the book for certain problems and say "get on with it". Is there scope for more ADF tombs like this?  Yes!  I'd love to see a cookbook specializing on ADF Business Components (hint hint to budding authors).

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  • A sample Memento pattern: Is it correct?

    - by TheSilverBullet
    Following this query on memento pattern, I have tried to put my understanding to test. Memento pattern stands for three things: Saving state of the "memento" object for its successful retrieval Saving carefully each valid "state" of the memento Encapsulating the saved states from the change inducer so that each state remains unaltered Have I achieved these three with my design? Problem This is a zero player game where the program is initialized with a particular set up of chess pawns - the knight and queen. Then program then needs to keep adding set of pawns or knights and queens so that each pawn is "safe" for the next one move of every other pawn. The condition is that either both pawns should be placed, or none of them should be placed. The chessboard with the most number of non conflicting knights and queens should be returned. Implementation I have 4 classes for this: protected ChessBoard (the Memento) private int [][] ChessBoard; public void ChessBoard(); protected void SetChessBoard(); protected void GetChessBoard(int); public Pawn This is not related to memento. It holds info about the pawns public enum PawnType: int { Empty = 0, Queen = 1, Knight = 2, } //This returns a value that shown if the pawn can be placed safely public bool IsSafeToAddPawn(PawnType); public CareTaker This corresponds to caretaker of memento This is a double dimentional integer array that keeps a track of all states. The reason for having 2D array is to keep track of how many states are stored and which state is currently active. An example: 0 -2 1 -1 2 0 - This is current state. With second index 0/ 3 1 - This state has been saved, but has been undone private int [][]State; private ChessBoard [] MChessBoard; //This gets the chessboard at the position requested and assigns it to originator public ChessBoard GetChessBoard(int); //This overwrites the chessboard at given position public void SetChessBoard(ChessBoard, int); private int [][]State; public PlayGame (This is the originator) private bool status; private ChessBoard oChessBoard; //This sets the state of chessboard at position specified public SetChessBoard(ChessBoard, int); //This gets the state of chessboard at position specified public ChessBoard GetChessBoard(int); //This function tries to place both the pawns and returns the status of this attempt public bool PlacePawns(Pawn);

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  • Ray Intersecting Plane Formula in C++/DirectX

    - by user4585
    I'm developing a picking system that will use rays that intersect volumes and I'm having trouble with ray intersection versus a plane. I was able to figure out spheres fairly easily, but planes are giving me trouble. I've tried to understand various sources and get hung up on some of the variables used within their explanations. Here is a snippet of my code: bool Picking() { D3DXVECTOR3 vec; D3DXVECTOR3 vRayDir; D3DXVECTOR3 vRayOrig; D3DXVECTOR3 vROO, vROD; // vect ray obj orig, vec ray obj dir D3DXMATRIX m; D3DXMATRIX mInverse; D3DXMATRIX worldMat; // Obtain project matrix D3DXMATRIX pMatProj = CDirectXRenderer::GetInstance()->Director()->Proj(); // Obtain mouse position D3DXVECTOR3 pos = CGUIManager::GetInstance()->GUIObjectList.front().pos; // Get window width & height float w = CDirectXRenderer::GetInstance()->GetWidth(); float h = CDirectXRenderer::GetInstance()->GetHeight(); // Transform vector from screen to 3D space vec.x = (((2.0f * pos.x) / w) - 1.0f) / pMatProj._11; vec.y = -(((2.0f * pos.y) / h) - 1.0f) / pMatProj._22; vec.z = 1.0f; // Create a view inverse matrix D3DXMatrixInverse(&m, NULL, &CDirectXRenderer::GetInstance()->Director()->View()); // Determine our ray's direction vRayDir.x = vec.x * m._11 + vec.y * m._21 + vec.z * m._31; vRayDir.y = vec.x * m._12 + vec.y * m._22 + vec.z * m._32; vRayDir.z = vec.x * m._13 + vec.y * m._23 + vec.z * m._33; // Determine our ray's origin vRayOrig.x = m._41; vRayOrig.y = m._42; vRayOrig.z = m._43; D3DXMatrixIdentity(&worldMat); //worldMat = aliveActors[0]->GetTrans(); D3DXMatrixInverse(&mInverse, NULL, &worldMat); D3DXVec3TransformCoord(&vROO, &vRayOrig, &mInverse); D3DXVec3TransformNormal(&vROD, &vRayDir, &mInverse); D3DXVec3Normalize(&vROD, &vROD); When using this code I'm able to detect a ray intersection via a sphere, but I have questions when determining an intersection via a plane. First off should I be using my vRayOrig & vRayDir variables for the plane intersection tests or should I be using the new vectors that are created for use in object space? When looking at a site like this for example: http://www.tar.hu/gamealgorithms/ch22lev1sec2.html I'm curious as to what D is in the equation AX + BY + CZ + D = 0 and how does it factor in to determining a plane intersection? Any help will be appreciated, thanks.

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  • Editing /.config/dconf/user

    - by user86322
    I am having a problem with Gnome3 (actually, I have it set to fallback mode, or Gnome 2). I have two displays and I need an X screen (I used nvidia-xconfig and nvidia-settings to do this) for each screen. However, every time I either restart X or log in, Gnome seems to be adding the objects values under /gnome/gnome-panel/layouts (ex. first time I set the two separate X screens I had clock, then log out/in, there was clock and clock1 under objects, and then log out/in there were three, clock, clock1, clock2,.......log out/in, ............30 times....clock, clock1, clock2, ......clock 42.....!! The same thing goes for top-panels, menu-bars, etc.) After a while, I found out I could remove all those using the dconf-editor, going to /gnome/gnome-panel/layouts, removing all the repetitions under fields objects-id-list and top-id-list and leaving one value of each object. This is not a solution but at least allow me to keep using Linux without so much problem. However, the problem persists every time I restart X or log in. I now finally learned about "dconf" and where the user profile settings are located (~/.config/dconf/user) and one can use "dconf" to see the keys. In my case, I need to change/remove many keys (all those clocksX, workspace-X, menu-bar-X, etc., where goes from 1 to 42 and still counting) so it's really tedious and boring to be changing one by one using "dconf write". So I found "dconf dump", which actually allow me to dump everything into a .txt file and edit the file really quick (i.e, "dconf dump / >> dump_user.txt"). The problems? Two of them: How do I "load" back "dump_user.txt" I edited into the user profile? (I read somewhere there was a "dconf reload" but reload doesn't exist as a command under "dconf") How do I stop Gnome from keep adding more objects to my desktop environment every time I log in/restart X? NOTE: The problem doesn't occur when I set the displays to use TwinView feature (i.e., the desktop is extended/shared by both displays). However, for my case I need two separate X's. Any help/suggestion would be greatly appreciated. Thanks

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  • Making a Camera look at a target Vector

    - by Peteyslatts
    I have a camera that works as long as its stationary. Now I'm trying to create a child class of that camera class that will look at its target. The new addition to the class is a method called SetTarget(). The method takes in a Vector3 target. The camera wont move but I need it to rotate to look at the target. If I just set the target, and then call CreateLookAt() (which takes in position, target, and up), when the object gets far enough away and underneath the camera, it suddenly flips right side up. So I need to transform the up vector, which currently always stays at Vector3.Up. I feel like this has something to do with taking the angle between the old direction vector and the new one (which I know can be expressed by target - position). I feel like this is all really vague, so here's the code for my base camera class: public class BasicCamera : Microsoft.Xna.Framework.GameComponent { public Matrix view { get; protected set; } public Matrix projection { get; protected set; } public Vector3 position { get; protected set; } public Vector3 direction { get; protected set; } public Vector3 up { get; protected set; } public Vector3 side { get { return Vector3.Cross(up, direction); } protected set { } } public BasicCamera(Game game, Vector3 position, Vector3 target, Vector3 up) : base(game) { this.position = position; this.direction = target - position; this.up = up; CreateLookAt(); projection = Matrix.CreatePerspectiveFieldOfView( MathHelper.PiOver4, (float)Game.Window.ClientBounds.Width / (float)Game.Window.ClientBounds.Height, 1, 500); } public override void Update(GameTime gameTime) { // TODO: Add your update code here CreateLookAt(); base.Update(gameTime); } } And this is the code for the class that extends the above class to look at its target. class TargetedCamera : BasicCamera { public Vector3 target { get; protected set; } public TargetedCamera(Game game, Vector3 position, Vector3 target, Vector3 up) : base(game, position, target, up) { this.target = target; } public void SetTarget(Vector3 target) { direction = target - position; } protected override void CreateLookAt() { view = Matrix.CreateLookAt(position, target, up); } }

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  • OpenGL ES 2 jittery camera movement

    - by user16547
    First of all, I am aware that there's no camera in OpenGL (ES 2), but from my understanding proper manipulation of the projection matrix can simulate the concept of a camera. What I'm trying to do is make my camera follow my character. My game is 2D, btw. I think the principle is the following (take Super Mario Bros or Doodle Jump as reference - actually I'm trying to replicate the mechanics of the latter): when the caracter goes beyond the center of the screen (in the positive axis/direction), update the camera to be centred on the character. Else keep the camera still. I did accomplish that, however the camera movement is noticeably jittery and I ran out of ideas how to make it smoother. First of all, my game loop (following this article): private int TICKS_PER_SECOND = 30; private int SKIP_TICKS = 1000 / TICKS_PER_SECOND; private int MAX_FRAMESKIP = 5; @Override public void run() { loops = 0; if(firstLoop) { nextGameTick = SystemClock.elapsedRealtime(); firstLoop = false; } while(SystemClock.elapsedRealtime() > nextGameTick && loops < MAX_FRAMESKIP) { step(); nextGameTick += SKIP_TICKS; loops++; } interpolation = ( SystemClock.elapsedRealtime() + SKIP_TICKS - nextGameTick ) / (float)SKIP_TICKS; draw(); } And the following code deals with moving the camera. I was unsure whether to place it in step() or draw(), but it doesn't make a difference to my problem at the moment, as I tried both and neither seemed to fix it. center just represents the y coordinate of the centre of the screen at any time. Initially it is 0. The camera object is my own custom "camera" which basically is a class that just manipulates the view and projection matrices. if(character.getVerticalSpeed() >= 0) { //only update camera if going up float[] projectionMatrix = camera.getProjectionMatrix(); if( character.getY() > center) { center += character.getVerticalSpeed(); cameraBottom = center + camera.getBottom(); cameraTop = center + camera.getTop(); Matrix.orthoM(projectionMatrix, 0, camera.getLeft(), camera.getRight(), center + camera.getBottom(), center + camera.getTop(), camera.getNear(), camera.getFar()); } } Any thought about what I should try or what I am doing wrong? Update 1: I think I updated every value you can see on screen to check whether the jittery movement is affected by that, but nothing changed, so something must be fundamentally flawed with my approach/calculations.

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  • Who should control navigation in an MVVM application?

    - by SonOfPirate
    Example #1: I have a view displayed in my MVVM application (let's use Silverlight for the purposes of the discussion) and I click on a button that should take me to a new page. Example #2: That same view has another button that, when clicked, should open up a details view in a child window (dialog). We know that there will be Command objects exposed by our ViewModel bound to the buttons with methods that respond to the user's click. But, what then? How do we complete the action? Even if we use a so-called NavigationService, what are we telling it? To be more specific, in a traditional View-first model (like URL-based navigation schemes such as on the web or the SL built-in navigation framework) the Command objects would have to know what View to display next. That seems to cross the line when it comes to the separation of concerns promoted by the pattern. On the other hand, if the button wasn't wired to a Command object and behaved like a hyperlink, the navigation rules could be defined in the markup. But do we want the Views to control application flow and isn't navigation just another type of business logic? (I can say yes in some cases and no in others.) To me, the utopian implementation of the MVVM pattern (and I've heard others profess this) would be to have the ViewModel wired in such a way that the application can run headless (i.e. no Views). This provides the most surface area for code-based testing and makes the Views a true skin on the application. And my ViewModel shouldn't care if it displayed in the main window, a floating panel or a child window, should it? According to this apprach, it is up to some other mechanism at runtime to 'bind' what View should be displayed for each ViewModel. But what if we want to share a View with multiple ViewModels or vice versa? So given the need to manage the View-ViewModel relationship so we know what to display when along with the need to navigate between views, including displaying child windows / dialogs, how do we truly accomplish this in the MVVM pattern?

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  • Fixing a NoClassDefFoundError

    - by Chris Okyen
    I have some code: package ftc; import java.util.Scanner; public class Fer_To_Cel { public static void main(String[] argv) { // Scanner object to get the temp in degrees Farenheit Scanner keyboard = new Scanner(System.in); boolean isInt = true; // temporarily put as true in case the user enters a valid int the first time int degreesF = 0; // initialy set to 0 do { try { // Input the temperature text. System.out.print("\nPlease enter a temperature (integer number, no fractional part) in degrees Farenheit: "); degreesF = Integer.parseInt(keyboard.next()); // Get user input and Assign the far. temperature variable, which is casted from String to int. } // Let the user know in a user friendly notice that the value entered wasnt an int ( give int value range ) , and then give error log catch(java.lang.Exception e) { System.out.println("Sorry but you entered a non-int value ( needs to be between ( including ) -2,147,483,648 and 2,147,483,647 ).. \n"); e.printStackTrace(); isInt = false; } } while(!isInt); System.out.println(""); // print a new line. final int degreesC = (5*(degreesF-32)/9); // convert the degrees from F to C and store the resulting expression in degreesC // Print out a newline, then print what X degrees F is in Celcius. System.out.println("\n" + degreesF + " degrees Farenheit is " + degreesC + " degrees Celcius"); } } And The following error: C:\Program Files\Java\jdk1.7.0_06\bin>java Fer_To_Cel Exception in thread "main" java.lang.NoClassDefFoundError: Fer_To_Cel (wrong name: ftc/Fer_To_Cel) at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:791) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:14 at java.net.URLClassLoader.defineClass(URLClassLoader.java:449) at java.net.URLClassLoader.access$100(URLClassLoader.java:71) at java.net.URLClassLoader$1.run(URLClassLoader.java:361) at java.net.URLClassLoader$1.run(URLClassLoader.java:355) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:354) at java.lang.ClassLoader.loadClass(ClassLoader.java:423) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308) at java.lang.ClassLoader.loadClass(ClassLoader.java:356) at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:480) The code compiled without compile errors, but presented errors during execution. Which leads me to two questions. I know Errors can be termed Compiler, Runtime and Logic Errors, but the NoClassDefFoundError inherits java.lang.LinkageError. Does that make it a Linker error, being niether of the three types of errors I listed, If I am right this is the answer. For someone else who obtains the singular .java file and compiles it, would this be the only way to solve this problem? Or can I (should I ) do/have done something to fix this problem? Basically, based on a basis of programming, is this a fault of me as the writer? Could this be done once on, my half and be distributed and not needed be done again?

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  • Why is Double.Parse so slow?

    - by alexhildyard
    I was recently investigating a bottleneck in one of my applications, which read a CSV file from disk using a TextReader a line at a time, split the tokens, called Double.Parse on each one, then shunted the results into an object list. I was surprised to find it was actually the Double.Parse which seemed to be taking up most of the time.Googling turned up this, which is a little unfocused in places but throws out some excellent ideas:It makes more sense to work with binary format directly, rather than coerce strings into doublesThere is a significant performance improvement in composing doubles directly from the byte stream via long intermediariesString.Split is inefficient on fixed length recordsIn fact it turned out that my problem was more insidious and also more mundane -- a simple case of bad data in, bad data out. Since I had been serialising my Doubles as strings, when I inadvertently divided by zero and produced a "NaN", this of course was serialised as well without error. And because I was reading in using Double.Parse, these "NaN" fields were also (correctly) populating real Double objects without error. The issue is that Double.Parse("NaN") is incredibly slow. In fact, it is of the order of 2000x slower than parsing a valid double. For example, the code below gave me results of 357ms to parse 1000 NaNs, versus 15ms to parse 100,000 valid doubles.            const int invalid_iterations = 1000;            const int valid_iterations = invalid_iterations * 100;            const string invalid_string = "NaN";            const string valid_string = "3.14159265";            DateTime start = DateTime.Now;                        for (int i = 0; i < invalid_iterations; i++)            {                double invalid_double = Double.Parse(invalid_string);            }            Console.WriteLine(String.Format("{0} iterations of invalid double, time taken (ms): {1}",                invalid_iterations,                ((TimeSpan)DateTime.Now.Subtract(start)).Milliseconds            ));            start = DateTime.Now;            for (int i = 0; i < valid_iterations; i++)            {                double valid_double = Double.Parse(valid_string);            }            Console.WriteLine(String.Format("{0} iterations of valid double, time taken (ms): {1}",                valid_iterations,                ((TimeSpan)DateTime.Now.Subtract(start)).Milliseconds            )); I think the moral is to look at the context -- specifically the data -- as well as the code itself. Once I had corrected my data, the performance of Double.Parse was perfectly acceptable, and while clearly it could have been improved, it was now sufficient to my needs.

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  • Single Responsibility Principle Implementation

    - by Mike S
    In my spare time, I've been designing a CMS in order to learn more about actual software design and architecture, etc. Going through the SOLID principles, I already notice that ideas like "MVC", "DRY", and "KISS", pretty much fall right into place. That said, I'm still having problems deciding if one of two implementations is the best choice when it comes to the Single Responsibility Principle. Implementation #1: class User getName getPassword getEmail // etc... class UserManager create read update delete class Session start stop class Login main class Logout main class Register main The idea behind this implementation is that all user-based actions are separated out into different classes (creating a possible case of the aptly-named Ravioli Code), but following the SRP to a "tee", almost literally. But then I thought that it was a bit much, and came up with this next implementation class UserView extends View getLogin //Returns the html for the login screen getShortLogin //Returns the html for an inline login bar getLogout //Returns the html for a logout button getRegister //Returns the html for a register page // etc... as needed class UserModel extends DataModel implements IDataModel // Implements no new methods yet, outside of the interface methods // Haven't figured out anything special to go here at the moment // All CRUD operations are handled by DataModel // through methods implemented by the interface class UserControl extends Control implements IControl login logout register startSession stopSession class User extends DataObject getName getPassword getEmail // etc... This is obviously still very organized, and still very "single responsibility". The User class is a data object that I can manipulate data on and then pass to the UserModel to save it to the database. All the user data rendering (what the user will see) is handled by UserView and it's methods, and all the user actions are in one space in UserControl (plus some automated stuff required by the CMS to keep a user logged in or to ensure that they stay out.) I personally can't think of anything wrong with this implementation either. In my personal feelings I feel that both are effectively correct, but I can't decide which one would be easier to maintain and extend as life goes on (despite leaning towards Implementation #1.) So what about you guys? What are your opinions on this? Which one is better? What basics (or otherwise, nuances) of that principle have I missed in either design?

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  • Bullet Physics - Casting a ray straight down from a rigid body (first person camera)

    - by Hydrocity
    I've implemented a first person camera using Bullet--it's a rigid body with a capsule shape. I've only been using Bullet for a few days and physics engines are new to me. I use btRigidBody::setLinearVelocity() to move it and it collides perfectly with the world. The only problem is the Y-value moves freely, which I temporarily solved by setting the Y-value of the translation vector to zero before the body is moved. This works for all cases except when falling from a height. When the body drops off a tall object, you can still glide around since the translate vector's Y-value is being set to zero, until you stop moving and fall to the ground (the velocity is only set when moving). So to solve this I would like to try casting a ray down from the body to determine the Y-value of the world, and checking the difference between that value and the Y-value of the camera body, and disable or slow down movement if the difference is large enough. I'm a bit stuck on simply casting a ray and determining the Y-value of the world where it struck. I've implemented this callback: struct AllRayResultCallback : public btCollisionWorld::RayResultCallback{ AllRayResultCallback(const btVector3& rayFromWorld, const btVector3& rayToWorld) : m_rayFromWorld(rayFromWorld), m_rayToWorld(rayToWorld), m_closestHitFraction(1.0){} btVector3 m_rayFromWorld; btVector3 m_rayToWorld; btVector3 m_hitNormalWorld; btVector3 m_hitPointWorld; float m_closestHitFraction; virtual btScalar addSingleResult(btCollisionWorld::LocalRayResult& rayResult, bool normalInWorldSpace) { if(rayResult.m_hitFraction < m_closestHitFraction) m_closestHitFraction = rayResult.m_hitFraction; m_collisionObject = rayResult.m_collisionObject; if(normalInWorldSpace){ m_hitNormalWorld = rayResult.m_hitNormalLocal; } else{ m_hitNormalWorld = m_collisionObject->getWorldTransform().getBasis() * rayResult.m_hitNormalLocal; } m_hitPointWorld.setInterpolate3(m_rayFromWorld, m_rayToWorld, m_closestHitFraction); return 1.0f; } }; And in the movement function, I have this code: btVector3 from(pos.x, pos.y + 1000, pos.z); // pos is the camera's rigid body position btVector3 to(pos.x, 0, pos.z); // not sure if 0 is correct for Y AllRayResultCallback callback(from, to); Base::getSingletonPtr()->m_btWorld->rayTest(from, to, callback); So I have the callback.m_hitPointWorld vector, which seems to just show the position of the camera each frame. I've searched Google for examples of casting rays, as well as the Bullet documentation, and it's been hard to just find an example. An example is really all I need. Or perhaps there is some method in Bullet to keep the rigid body on the ground? I'm using Ogre3D as a rendering engine, and casting a ray down is quite straightforward with that, however I want to keep all the ray casting within Bullet for simplicity. Could anyone point me in the right direction? Thanks.

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  • Is it evil to model JSON responses to classes when they are mostly smilar?

    - by Aybe
    Here's the problem : While implementing a C# wrapper for an online API (Discogs) I've been faced to a dilemma : quite often the responses returned have mostly similar members and while modeling these responses to classes, some questions surfaces on which way to go would be the best. Example : Querying for a 'release' or a 'master' will return an object that contains an array of 'artist', however these 'artists' do not exactly have the same members. Currently I decided to represent these 'artists' as a single 'Artist' class, against having respective 'ReleaseArtist' and 'MasterArtist' classes which soon becomes very confusing even though another problem arises : when a category (master or release) does not return these members, they will be null. Though it might sound confusing as well I find it less confusing than the former situation as I've tackled the problem by simply not showing null members when visualizing these objects. Is this the right approach to follow ? An example of these differences : public class Artist { public List<Alias> Aliases { get; set; } public string DataQuality { get; set; } public List<Image> Images { get; set; } public string Name { get; set; } public List<string> NameVariations { get; set; } public string Profile { get; set; } public string Realname { get; set; } public string ReleasesUrl { get; set; } public string ResourceUrl { get; set; } public string Uri { get; set; } public List<string> Urls { get; set; } } public class ReleaseArtist { public string Join { get; set; } public string Name { get; set; } public string Anv { get; set; } public string Tracks { get; set; } public string Role { get; set; } public string ResourceUrl { get; set; } public int Id { get; set; } }

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  • How to handle encryption key conflicts when synchronizing data?

    - by Rafael
    Assume that there is data that gets synchronized between several devices. The data is protected with a symmetric encryption algorithm and a key. The key is stored on each device and encrypted with a password. When a user changes the password only the key gets re-encrypted. Under normal circumstances, when there is a good network connection to other peers, the current key gets synchronized and all data on the new device gets encrypted with the same key. But how to handle situations where a new device doesn’t have a network connection and e.g. creates its own new, but incompatible key? How to keep the usability as high as possible under such circumstances? The application could detect that there is no network and hence refuse to start. That’s very bad usability in my opinion, because the application isn’t functional at all in this case. I don’t consider this a solution. The application could ignore the missing network connection and create a new key. But what to do when the application gains a network connection? There will be several incompatible keys and some parts of the underlying data could only be encrypted with one key and other parts with another key. The situation would get worse if there would be more keys than just two and the application would’ve to ask every time for a password when another object that should get decrypted with another key would be needed. It is very messy and time consuming to try to re-encrypt all data that is encrypted with another key with a main key. What should be the main key at all in this case? The oldest key? The key with the most encrypted objects? What if the key got synchronized but not all objects that got encrypted with this particular key? How should the user know for which particular password the application asks and why it takes probably very long to re-encrypt the data? It’s very hard to describe encryption “issues” to users. So far I didn’t find an acceptable solution, nor some kind of generic strategy. Do you have some hints about a concrete strategy or some books / papers that describe synchronization of symmetrically encrypted data with keys that could cause conflicts?

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  • Quaternion based rotation and pivot position

    - by Michael IV
    I can't figure out how to perform matrix rotation using Quaternion while taking into account pivot position in OpenGL.What I am currently getting is rotation of the object around some point in the space and not a local pivot which is what I want. Here is the code [Using Java] Quaternion rotation method: public void rotateTo3(float xr, float yr, float zr) { _rotation.x = xr; _rotation.y = yr; _rotation.z = zr; Quaternion xrotQ = Glm.angleAxis((xr), Vec3.X_AXIS); Quaternion yrotQ = Glm.angleAxis((yr), Vec3.Y_AXIS); Quaternion zrotQ = Glm.angleAxis((zr), Vec3.Z_AXIS); xrotQ = Glm.normalize(xrotQ); yrotQ = Glm.normalize(yrotQ); zrotQ = Glm.normalize(zrotQ); Quaternion acumQuat; acumQuat = Quaternion.mul(xrotQ, yrotQ); acumQuat = Quaternion.mul(acumQuat, zrotQ); Mat4 rotMat = Glm.matCast(acumQuat); _model = new Mat4(1); scaleTo(_scaleX, _scaleY, _scaleZ); _model = Glm.translate(_model, new Vec3(_pivot.x, _pivot.y, 0)); _model =rotMat.mul(_model);//_model.mul(rotMat); //rotMat.mul(_model); _model = Glm.translate(_model, new Vec3(-_pivot.x, -_pivot.y, 0)); translateTo(_x, _y, _z); notifyTranformChange(); } Model matrix scale method: public void scaleTo(float x, float y, float z) { _model.set(0, x); _model.set(5, y); _model.set(10, z); _scaleX = x; _scaleY = y; _scaleZ = z; notifyTranformChange(); } Translate method: public void translateTo(float x, float y, float z) { _x = x - _pivot.x; _y = y - _pivot.y; _z = z; _position.x = _x; _position.y = _y; _position.z = _z; _model.set(12, _x); _model.set(13, _y); _model.set(14, _z); notifyTranformChange(); } But this method in which I don't use Quaternion works fine: public void rotate(Vec3 axis, float angleDegr) { _rotation.add(axis.scale(angleDegr)); // change to GLM: Mat4 backTr = new Mat4(1.0f); backTr = Glm.translate(backTr, new Vec3(_pivot.x, _pivot.y, 0)); backTr = Glm.rotate(backTr, angleDegr, axis); backTr = Glm.translate(backTr, new Vec3(-_pivot.x, -_pivot.y, 0)); _model =_model.mul(backTr);///backTr.mul(_model); notifyTranformChange(); }

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  • Contract / Project / Line-Item hierarchy design considerations

    - by Ryan
    We currently have an application that allows users to create a Contract. A contract can have 1 or more Project. A project can have 0 or more sub-projects (which can have their own sub-projects, and so on) as well as 1 or more Line. Lines can have any number of sub-lines (which can have their own sub-lines, and so on). Currently, our design contains circular references, and I'd like to get away from that. Currently, it looks a bit like this: public class Contract { public List<Project> Projects { get; set; } } public class Project { public Contract OwningContract { get; set; } public Project ParentProject { get; set; } public List<Project> SubProjects { get; set; } public List<Line> Lines { get; set; } } public class Line { public Project OwningProject { get; set; } public List ParentLine { get; set; } public List<Line> SubLines { get; set; } } We're using the M-V-VM "pattern" and use these Models (and their associated view models) to populate a large "edit" screen where users can modify their contracts and the properties on all of the objects. Where things start to get confusing for me is when we add, for example, a Cost property to the Line. The issue is reflecting at the highest level (the contract) changes made to the lowest level. Looking for some thoughts as to how to change this design to remove the circular references. One thought I had was that the contract would have a Dictionary<Guid, Project> which would contain ALL projects (regardless of their level in hierarchy). The Project would then have a Guid property called "Parent" which could be used to search the contract's dictionary for the parent object. THe same logic could be applied at the Line level. Thanks! Any help is appreciated.

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  • Create a kind of Interface c++ [migrated]

    - by Liuka
    I'm writing a little 2d rendering framework with managers for input and resources like textures and meshes (for 2d geometry models, like quads) and they are all contained in a class "engine" that interacts with them and with a directX class. So each class have some public methods like init or update. They are called by the engine class to render the resources, create them, but a lot of them should not be called by the user: //in pseudo c++ //the textures manager class class TManager { private: vector textures; .... public: init(); update(); renderTexture(); //called by the "engine class" loadtexture(); gettexture(); //called by the user } class Engine { private: Tmanager texManager; public: Init() { //initialize all the managers } Render(){...} Update(){...} Tmanager* GetTManager(){return &texManager;} //to get a pointer to the manager //if i want to create or get textures } In this way the user, calling Engine::GetTmanager will have access to all the public methods of Tmanager, including init update and rendertexture, that must be called only by Engine inside its init, render and update functions. So, is it a good idea to implement a user interface in the following way? //in pseudo c++ //the textures manager class class TManager { private: vector textures; .... public: init(); update(); renderTexture(); //called by the "engine class" friend class Tmanager_UserInterface; operator Tmanager_UserInterface*(){return reinterpret_cast<Tmanager_UserInterface*>(this)} } class Tmanager_UserInterface : private Tmanager { //delete constructor //in this class there will be only methods like: loadtexture(); gettexture(); } class Engine { private: Tmanager texManager; public: Init() Render() Update() Tmanager_UserInterface* GetTManager(){return texManager;} } //in main function //i need to load a texture //i always have access to Engine class engine-GetTmanger()-LoadTexture(...) //i can just access load and get texture; In this way i can implement several interface for each object, keeping visible only the functions i (and the user) will need. There are better ways to do the same?? Or is it just useless(i dont hide the "framework private functions" and the user will learn to dont call them)? Before i have used this method: class manager { public: //engine functions userfunction(); } class engine { private: manager m; public: init(){//call manager init function} manageruserfunciton() { //call manager::userfunction() } } in this way i have no access to the manager class but it's a bad way because if i add a new feature to the manager i need to add a new method in the engine class and it takes a lot of time. sorry for the bad english.

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  • Behaviour Trees with irregular updates

    - by Robominister
    I'm interested in behaviour trees that aren't iterated every game tick, but every so often. (Edit: the tree could specify how many frames within the main game loop to wait before running its tick function again). Every theoretical implementation I have seen of behaviour trees talks of the tree search being carried out every game update - which seems necessary, because a leaf node (eg a behaviour, like 'return to base') needs to be constantly checked to see if is still running, failed or completed. Can anyone suggest how I might start implementing a tree that isnt run every tick, or point me in the direction of good material specific to this case (I am struggling to find anything)? My thoughts so far: action leaf nodes (when they start) must only push some kind of action object onto a list for an entity, rather than directly calling any code that makes the entity do something. The list of actions for the entity would be run every frame (update any that need to run, pop any that have completed from the list). the return state from a given action must be fed back into the tree, so that when we run the tree iteration again (and reach the same action leaf node - so the tree has so far determined that we ought to still be trying this action) - that the action has completed, or is still running etc. If my actual action code is running from an action list on an entity, then I possibly need to cancel previously running actions in the list - i am thinking that I can just delete the entire stack of queued up actions. I've seen the idea of ActionLists which block lower priority actions when a higher priority one is added, but this seems like very close logic to behaviour trees, and I dont want to be duplicating behaviour. This leaves me with some questions 1) How would I feed the action return state back into the tree? Its obvious I need to store some information relating to 'currently executing actions' on the entity, and check that in the tree tick, but I can't imagine how. 2) Does having a seperate behaviour tree (for deciding behaviour) and action list (for carrying out actual queued up actions) sound like a reasonable approach? 3) Is the approach of updating a behaviour tree irregularly actually used by anyone? It seems like a nice idea for budgeting ai search time when you have a lot of ai entities to process. (Edit) - I am also thinking about storing a single instance of a given behaviour tree in memory, and providing it by reference to any entity that uses it. So any information about what action was last selected for execution on an entity must be stored in a data context relative to the entity (which the tree can check). (I am probably answering my own questions as i go!) I hope I have expressed my questions adequately! Thanks in advance for any help :)

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  • C# OpenGL problem with animation

    - by user3696303
    there is a program that simulates a small satellite and requires that a rotation animation of the satellite along the three axes. But when you try to write an animation problem during compilation: the program simply closes (shutdown occurs when swapbuffers, mainloop, redisplay), when you write the easiest programs have the same problem arose. Trying to catch exception by try-catch but here is not exception. How to solve this? I suffer with this a few days. Work in c# visual studio 2008 framework namespace WindowsFormsApplication6 { public partial class Form1 : Form { public Form1() { try { InitializeComponent(); AnT1.InitializeContexts(); } catch(Exception) { Glut.glutDisplayFunc(Draw); Glut.glutTimerFunc(50, Timer, 0); Glut.glutMainLoop(); } } void Timer(int Unused) { Glut.glutPostRedisplay(); Glut.glutTimerFunc(50, Timer, 0); } private void AnT1_Load(object sender, EventArgs e) { Glut.glutInit(); Glut.glutInitDisplayMode(Glut.GLUT_RGB | Glut.GLUT_DOUBLE | Glut.GLUT_DEPTH); Gl.glClearColor(255, 255, 255, 1); Gl.glViewport(0, 0, AnT1.Width, AnT1.Height); Gl.glMatrixMode(Gl.GL_PROJECTION); Gl.glLoadIdentity(); Glu.gluPerspective(45, (float)AnT1.Width / (float)AnT1.Height, 0.1, 200); Gl.glMatrixMode(Gl.GL_MODELVIEW); Gl.glLoadIdentity(); Gl.glEnable(Gl.GL_DEPTH_TEST); Gl.glClear(Gl.GL_COLOR_BUFFER_BIT | Gl.GL_DEPTH_BUFFER_BIT); Gl.glPushMatrix(); double xy = 0.2; Gl.glTranslated(xy, 0, 0); xy += 0.2; Draw(); Glut.glutSwapBuffers(); Glut.glutPostRedisplay(); Gl.glPushMatrix(); Draw(); Gl.glPopMatrix(); } void Draw() { Gl.glLoadIdentity(); Gl.glColor3f(0.502f, 0.502f, 0.502f); Gl.glTranslated(-1, 0, -6); Gl.glRotated(95, 1, 0, 0); Glut.glutSolidCylinder(0.7, 2, 60, 60); Gl.glLoadIdentity(); Gl.glColor3f(0, 0, 0); Gl.glTranslated(-1, 0, -6); Gl.glRotated(95, 1, 0, 0); Glut.glutWireCylinder(0.7, 2, 20, 20); } } }

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  • SFX Played Once per Collision or Hit

    - by David Dimalanta
    I have a question about using Box2D (engine for LibGDX used to make realistic physics). I observed on the code that I've made for the physics here below: @Override public boolean touchUp(int screenX, int screenY, int pointer, int button) { // TODO Touch Up Event if(is_Next_Fruit_Touched) { BodyEditorLoader Fruit_Loader = new BodyEditorLoader(Gdx.files.internal("Shape_Physics/Fruity Physics.json")); Fruit_BD.type = BodyType.DynamicBody; Fruit_BD.position.set(x, y); FixtureDef Fruit_FD = new FixtureDef(); // --> Allows you to make the object's physics. Fruit_FD.density = 1.0f; Fruit_FD.friction = 0.7f; Fruit_FD.restitution = 0.2f; MassData mass = new MassData(); mass.mass = 5f; Fruit_Body[n] = world.createBody(Fruit_BD); Fruit_Body[n].setActive(true); // --> Let your dragon fall. Fruit_Body[n].setMassData(mass); Fruit_Body[n].setGravityScale(1.0f); System.out.println("Eggs... " + n); Fruit_Loader.attachFixture(Fruit_Body[n], Body, Fruit_FD, Fruit_IMG.getWidth()); Fruit_Origin = Fruit_Loader.getOrigin(Body, Fruit_IMG.getWidth()).cpy(); is_Next_Fruit_Touched = false; up = y; Gdx.app.log("Initial Y-coordinate", "Y at " + up); //Once it's touched, the next fruit will set to drag. if(n < 50) { n++; }else{ System.exit(0); } } return true; } Now, I'm thinking which part o line should I implement for the sound effects. My objectives to make SFX played once for every collision (Or should I say "SFX played once per collision"?) on the following: SFX played once if they hit on the objects of its kind. (e.g. apple vs. apple) SFX played once on a different sound when it hit on the ground. (e.g. apple land on the mud) Take note that I'm using Box2D for the Java programming version thanks to LibGDX via Box2D engine and I edited the physics body using Physics Body Editor before I implement it to code. I tried to check every available methods for body, fixture definition, or body definition to code for the SFX when hit but it seems only for the gravity and weight. Is there possibly available on the document for SFX played when collision happens if possible?

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  • How to keep a data structure synchronized over a network?

    - by David Gouveia
    Context In the game I'm working on (a sort of a point and click graphic adventure), pretty much everything that happens in the game world is controlled by an action manager that is structured a bit like: So for instance if the result of examining an object should make the character say hello, walk a bit and then sit down, I simply spawn the following code: var actionGroup = actionManager.CreateGroup(); actionGroup.Add(new TalkAction("Guybrush", "Hello there!"); actionGroup.Add(new WalkAction("Guybrush", new Vector2(300, 300)); actionGroup.Add(new SetAnimationAction("Guybrush", "Sit")); This creates a new action group (an entire line in the image above) and adds it to the manager. All of the groups are executed in parallel, but actions within each group are chained together so that the second one only starts after the first one finishes. When the last action in a group finishes, the group is destroyed. Problem Now I need to replicate this information across a network, so that in a multiplayer session, all players see the same thing. Serializing the individual actions is not the problem. But I'm an absolute beginner when it comes to networking and I have a few questions. I think for the sake of simplicity in this discussion we can abstract the action manager component to being simply: var actionManager = new List<List<string>>(); How should I proceed to keep the contents of the above data structure syncronized between all players? Besides the core question, I'm also having a few other concerns related to it (i.e. all possible implications of the same problem above): If I use a server/client architecture (with one of the players acting as both a server and a client), and one of the clients has spawned a group of actions, should he add them directly to the manager, or only send a request to the server, which in turn will order every client to add that group? What about packet losses and the like? The game is deterministic, but I'm thinking that any discrepancy in the sequence of actions executed in a client could lead to inconsistent states of the world. How do I safeguard against that sort of problem? What if I add too many actions at once, won't that cause problems for the connection? Any way to alleviate that?

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  • ssao implementation

    - by Irbis
    I try to implement a ssao based on this tutorial: link I use a deferred rendering and world coordinates for shading calculations. When saving gbuffer a vertex shader output looks like this: worldPosition = vec3(ModelMatrix * vec4(inPosition, 1.0)); normal = normalize(normalModelMatrix * inNormal); gl_Position = ProjectionMatrix * ViewMatrix * ModelMatrix * vec4(inPosition, 1.0); Next for a ssao calculations I render a scene as a full screen quad and I save an occlusion parameter in a texture. (Vertex positions in the world space: link Normals in the world space: link) SSAO implementation: subroutine (RenderPassType) void ssao() { vec2 texCoord = CalcTexCoord(); vec3 worldPos = texture(texture0, texCoord).xyz; vec3 normal = normalize(texture(texture1, texCoord).xyz); vec2 noiseScale = vec2(screenSize.x / 4, screenSize.y / 4); vec3 rvec = texture(texture2, texCoord * noiseScale).xyz; vec3 tangent = normalize(rvec - normal * dot(rvec, normal)); vec3 bitangent = cross(normal, tangent); mat3 tbn = mat3(tangent, bitangent, normal); float occlusion = 0.0; float radius = 4.0; for (int i = 0; i < kernelSize; ++i) { vec3 pix = tbn * kernel[i]; pix = pix * radius + worldPos; vec4 offset = vec4(pix, 1.0); offset = ProjectionMatrix * ViewMatrix * offset; offset.xy /= offset.w; offset.xy = offset.xy * 0.5 + 0.5; float sample_depth = texture(texture0, offset.xy).z; float range_check = abs(worldPos.z - sample_depth) < radius ? 1.0 : 0.0; occlusion += (sample_depth <= pix.z ? 1.0 : 0.0); } outputColor = vec4(occlusion, occlusion, occlusion, 1); } That code gives following results: camera looking towards -z world space: link camera looking towards +z world space: link I wonder if it is possible to use world coordinates in the above code ? When I move camera I get different results because world space positions don't change. Can I treat worldPos.z as a linear depth ? What should I change to get a correct results ? I except the white areas in place of occlusion, so the ground should has the white areas only near to the object.

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  • root issues in softwarecenter, synaptic and update manager

    - by user188977
    i have a notebook samsung ativ 2 and ubuntu 12.04 precise, cinnamon desktop. after logging in today my update manager, synaptic and ubuntu softwarecenter stopped working. synaptic i can only launch from terminal the others from panel.when choosing to update, nothing happens. same thing when trying to install programms from syn. or softw.center.when launching softwarec. from terminal i get: marcus@ddddddddd:~$ software-center 2013-11-10 22:30:46,206 - softwarecenter.ui.gtk3.app - INFO - setting up proxy 'None' 2013-11-10 22:30:46,217 - softwarecenter.db.database - INFO - open() database: path=None use_axi=True use_agent=True (software-center:4772): Gtk-WARNING **: Theme parsing error: softwarecenter.css:34:20: Not using units is deprecated. Assuming 'px'. (software-center:4772): Gtk-WARNING **: Theme parsing error: softwarecenter.css:34:22: Not using units is deprecated. Assuming 'px'. (software-center:4772): Gtk-WARNING **: Theme parsing error: softwarecenter.css:56:20: Not using units is deprecated. Assuming 'px'. (software-center:4772): Gtk-WARNING **: Theme parsing error: softwarecenter.css:56:22: Not using units is deprecated. Assuming 'px'. (software-center:4772): Gtk-WARNING **: Theme parsing error: softwarecenter.css:60:20: Not using units is deprecated. Assuming 'px'. (software-center:4772): Gtk-WARNING **: Theme parsing error: softwarecenter.css:60:22: Not using units is deprecated. Assuming 'px'. 2013-11-10 22:30:46,977 - softwarecenter.backend.reviews - WARNING - Could not get usefulness from server, no username in config file 2013-11-10 22:30:47,320 - softwarecenter.ui.gtk3.app - INFO - show_available_packages: search_text is '', app is None. 2013-11-10 22:30:48,057 - softwarecenter.db.pkginfo_impl.aptcache - INFO - aptcache.open() 2013-11-10 22:31:00,646 - softwarecenter.fixme - WARNING - logs to the root logger: '('/usr/share/software-center/softwarecenter/utils.py', 201, 'get_title_from_html')' 2013-11-10 22:31:00,645 - root - WARNING - failed to parse: '<div style="background-color: #161513; width:1680px; height:200px;">  <div style="background: url('/site_media/exhibits/2013/09/AAMFP_Leaderboard_700x200_1.jpg') top left no-repeat; width:700px; height:200px;"></div> </div>' ('ascii' codec can't encode character u'\xa0' in position 70: ordinal not in range(128)) 2013-11-10 22:31:02,268 - softwarecenter.db.update - INFO - skipping region restricted app: 'Comentarios Web' (not whitelisted) 2013-11-10 22:31:02,769 - softwarecenter.db.update - INFO - skipping region restricted app: 'reEarCandy' (not whitelisted) 2013-11-10 22:31:04,821 - softwarecenter.db.update - INFO - skipping region restricted app: 'Flaggame' (not whitelisted) 2013-11-10 22:31:05,622 - softwarecenter.db.update - INFO - skipping region restricted app: 'Bulleti d'esquerra de Calonge i Sant Antoni ' (not whitelisted) 2013-11-10 22:31:08,352 - softwarecenter.ui.gtk3.app - INFO - software-center-agent finished with status 0 2013-11-10 22:31:08,353 - softwarecenter.db.database - INFO - reopen() database 2013-11-10 22:31:08,353 - softwarecenter.db.database - INFO - open() database: path=None use_axi=True use_agent=True 2013-11-10 22:33:32,319 - softwarecenter.backend - WARNING - _on_trans_error: org.freedesktop.PolicyKit.Error.Failed: ('system-bus-name', {'name': ':1.72'}): org.debian.apt.install-or-remove-packages 2013-11-10 22:36:01,818 - softwarecenter.backend - WARNING - daemon dies, ignoring: <AptTransaction object at 0x48e4b40 (aptdaemon+client+AptTransaction at 0x645aaa0)> exit-failed 2013-11-10 22:36:01,820 - softwarecenter.db.pkginfo_impl.aptcache - INFO - aptcache.open()

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  • Antenna Aligner Part 5: Devil is in the detail

    - by Chris George
    "The first 90% of a project takes 90% of the time and the last 10% takes the another 200%"  (excerpt from onista) Now that I have a working app (more or less), it's time to make it pretty and slick. I can't stress enough how useful it is to get other people using your software, and my simple app is no exception. I handed my iPhone to a couple of my colleagues at Red Gate and asked them to use it and give me feedback. Immediately it became apparent that the delay between the list page being shown and the list being drawn was too long, and everyone who tried the app clicked on the "Recalculate" button before it had finished. Similarly, selecting a transmitter heralded a delay before the compass page appeared with similar consequences. All users expected there to be some sort of feedback/spinny etc. to show them it is actually doing something. In a similar vein although for opposite reasons, clicking the Recalculate button did indeed recalculate the available transmitters and redraw them, but it did this too fast! One or two users commented that they didn't know if it had done anything. All of these issues resulted in similar solutions; implement a waiting spinny. Thankfully, jquery mobile has one built in, primarily used for ajax operations. Not wishing to bore you with the many many iterations I went through trying to get this to work, I'll just give you my solution! (Seriously, I was working on this most evenings for at least a week!) The final solution for the recalculate problem came in the form of the code below. $(document).on("click", ".show-page-loading-msg", function () {            var $this = $(this),                theme = $this.jqmData("theme") ||                        $.mobile.loadingMessageTheme;            $.mobile.showPageLoadingMsg(theme, "recalculating", false);            setTimeout(function ()                           { $.mobile.hidePageLoadingMsg(); }, 2000);            getLocationData();        })        .on("click", ".hide-page-loading-msg", function () {              $.mobile.hidePageLoadingMsg();        }); The spinny is activated by setting the class of a button (for example) to the 'show-page-loading-msg' class. &lt;a data-role="button" class="show-page-loading-msg"Recalculate This means the code above is fired, calling the showPageLoadingMsg on the document.mobile object. Then, after a 2 second timeout, it calls the hidePageLoadingMsg() function. Supposedly, it should show "recalculating" underneath the spinny, but I've not got that to work. I'm wondering if there is a problem with the jquery mobile implementation. Anyway, it doesn't really matter, it's the principle I'm after, and I now have spinnys!

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  • C# Dev - I've tried Lisps, but I don't get it.

    - by Jonathan Mitchem
    After a few months of learning about and playing with lisps, both CL and a bit of Clojure, I'm still not seeing a compelling reason to write anything in it instead of C#. I would really like some compelling reasons, or for someone to point out that I'm missing something really big. The strengths of a Lisp (per my research): Compact, expressive notation - More so than C#, yes... but I seem to be able to express those ideas in C# too. Implicit support for functional programming - C# with LINQ extension methods: mapcar = .Select( lambda ) mapcan = .Select( lambda ).Aggregate( (a,b) = a.Union(b) ) car/first = .First() cdr/rest = .Skip(1) .... etc. Lambda and higher-order function support - C# has this, and the syntax is arguably simpler: "(lambda (x) ( body ))" versus "x = ( body )" "#(" with "%", "%1", "%2" is nice in Clojure Method dispatch separated from the objects - C# has this through extension methods Multimethod dispatch - C# does not have this natively, but I could implement it as a function call in a few hours Code is Data (and Macros) - Maybe I haven't "gotten" macros, but I haven't seen a single example where the idea of a macro couldn't be implemented as a function; it doesn't change the "language", but I'm not sure that's a strength DSLs - Can only do it through function composition... but it works Untyped "exploratory" programming - for structs/classes, C#'s autoproperties and "object" work quite well, and you can easily escalate into stronger typing as you go along Runs on non-Windows hardware - Yeah, so? Outside of college, I've only known one person who doesn't run Windows at home, or at least a VM of Windows on *nix/Mac. (Then again, maybe this is more important than I thought and I've just been brainwashed...) The REPL for bottom-up design - Ok, I admit this is really really nice, and I miss it in C#. Things I'm missing in a Lisp (due to a mix of C#, .NET, Visual Studio, Resharper): Namespaces. Even with static methods, I like to tie them to a "class" to categorize their context (Clojure seems to have this, CL doesn't seem to.) Great compile and design-time support the type system allows me to determine "correctness" of the datastructures I pass around anything misspelled is underlined realtime; I don't have to wait until runtime to know code improvements (such as using an FP approach instead of an imperative one) are autosuggested GUI development tools: WinForms and WPF (I know Clojure has access to the Java GUI libraries, but they're entirely foreign to me.) GUI Debugging tools: breakpoints, step-in, step-over, value inspectors (text, xml, custom), watches, debug-by-thread, conditional breakpoints, call-stack window with the ability to jump to the code at any level in the stack (To be fair, my stint with Emacs+Slime seemed to provide some of this, but I'm partial to the VS GUI-driven approach) I really like the hype surrounding Lisps and I gave it a chance. But is there anything I can do in a Lisp that I can't do as well in C#? It might be a bit more verbose in C#, but I also have autocomplete. What am I missing? Why should I use Clojure/CL?

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