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• XNA Multiplayer Games and Networking

  - by JoshReuben

  ·        XNA communication must by default be lightweight – if you are syncing game state between players from the Game.Update method, you must minimize traffic. That game loop may be firing 60 times a second and player 5 needs to know if his tank has collided with any player 3 and the angle of that gun turret. There are no WCF ServiceContract / DataContract niceties here, but at the same time the XNA networking stack simplifies the details. The payload must be simplistic - just an ordered set of numbers that you would map to meaningful enum values upon deserialization.   Overview ·        XNA allows you to create and join multiplayer game sessions, to manage game state across clients, and to interact with the friends list ·        Dependency on Gamer Services - to receive notifications such as sign-in status changes and game invitations ·        two types of online multiplayer games: system link game sessions (LAN) and LIVE sessions (WAN). ·        Minimum dev requirements: 1 Xbox 360 console + Creators Club membership to test network code - run 1 instance of game on Xbox 360, and 1 on a Windows-based computer   Network Sessions ·        A network session is made up of players in a game + up to 8 arbitrary integer properties describing the session ·        create custom enums – (e.g. GameMode, SkillLevel) as keys in NetworkSessionProperties collection ·        Player state: lobby, in-play   Session Types ·        local session - for split-screen gaming - requires no network traffic. ·        system link session - connects multiple gaming machines over a local subnet. ·        Xbox LIVE multiplayer session - occurs on the Internet. Ranked or unranked   Session Updates ·        NetworkSession class Update method - must be called once per frame. ·        performs the following actions: o   Sends the network packets. o   Changes the session state. o   Raises the managed events for any significant state changes. o   Returns the incoming packet data. ·        synchronize the session à packet-received and state-change events à no threading issues   Session Config ·        Session host - gaming machine that creates the session. XNA handles host migration ·        NetworkSession properties: AllowJoinInProgress , AllowHostMigration ·        NetworkSession groups: AllGamers, LocalGamers, RemoteGamers   Subscribe to NetworkSession events ·        GamerJoined ·        GamerLeft ·        GameStarted ·        GameEnded – use to return to lobby ·        SessionEnded – use to return to title screen   Create a Session session = NetworkSession.Create(         NetworkSessionType.SystemLink,         maximumLocalPlayers,         maximumGamers,         privateGamerSlots,         sessionProperties );   Start a Session if (session.IsHost) {     if (session.IsEveryoneReady)     {        session.StartGame();        foreach (var gamer in SignedInGamer.SignedInGamers)        {             gamer.Presence.PresenceMode =                 GamerPresenceMode.InCombat;   Find a Network Session AvailableNetworkSessionCollection availableSessions = NetworkSession.Find(     NetworkSessionType.SystemLink,       maximumLocalPlayers,     networkSessionProperties); availableSessions.AllowJoinInProgress = true;   Join a Network Session NetworkSession session = NetworkSession.Join(     availableSessions[selectedSessionIndex]);   Sending Network Data var packetWriter = new PacketWriter(); foreach (LocalNetworkGamer gamer in session.LocalGamers) {     // Get the tank associated with this player.     Tank myTank = gamer.Tag as Tank;     // Write the data.     packetWriter.Write(myTank.Position);     packetWriter.Write(myTank.TankRotation);     packetWriter.Write(myTank.TurretRotation);     packetWriter.Write(myTank.IsFiring);     packetWriter.Write(myTank.Health);       // Send it to everyone.     gamer.SendData(packetWriter, SendDataOptions.None);     }   Receiving Network Data foreach (LocalNetworkGamer gamer in session.LocalGamers) {     // Keep reading while packets are available.     while (gamer.IsDataAvailable)     {         NetworkGamer sender;          // Read a single packet.         gamer.ReceiveData(packetReader, out sender);          if (!sender.IsLocal)         {             // Get the tank associated with this packet.             Tank remoteTank = sender.Tag as Tank;              // Read the data and apply it to the tank.             remoteTank.Position = packetReader.ReadVector2();             …   End a Session if (session.AllGamers.Count == 1)         {             session.EndGame();             session.Update();         }   Performance •        Aim to minimize payload, reliable in order messages •        Send Data Options: o   Unreliable, out of order -(SendDataOptions.None) o   Unreliable, in order (SendDataOptions.InOrder) o   Reliable, out of order (SendDataOptions.Reliable) o   Reliable, in order (SendDataOptions.ReliableInOrder) o   Chat data (SendDataOptions.Chat) •        Simulate: NetworkSession.SimulatedLatency , NetworkSession.SimulatedPacketLoss •        Voice support – NetworkGamer properties: HasVoice ,IsTalking , IsMutedByLocalUser

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• Building Tag Cloud Declarative ADF Component

  - by Arunkumar Ramamoorthy

  When building a website, there could a requirement to add a tag cloud to let the users know the popular tags (or terms) used in the site. In this blog, we would build a simple declarative component to be used as tag cloud in the page. To start with, we would first create the declarative component, which could display the tag cloud. We will do that by creating a new custom application from the new gallery. Give a name for the app and the project and from the new gallery, let us create a new ADF Declarative Component We need to specify the name for the declarative component, attributes in it etc. as follows For displaying the tags as cloud, we need to pass the content to this component. So, we will create an attribute to hold the values for the tag. Let us name it as "value" and make it as java.lang.String  type. Once after this, to hold the component, we need to create a tag library. This can be done by clicking on the Add Tag Library button. Clicking on OK buttons in all the open dialogs would create a declarative component for us. Now, we need to display the tag cloud based on the value passed to the component. To do that, we assume that the value is a Tree Binding and has two attributes in it, say "Name" and "Weight". To make a tag cloud, we would put together the "Name" in a loop and set it's font size based on the "Weight". After putting our logic to work, here is how the source look Attributes added to the declarative components can be retrieved by using #{attrs.<attribute_name>}. Now, we need to deploy this project as ADF Library Jar file, so that this can be distributed to the consuming applications. We'll select ADF Library Jar as type and create the profile. We would be getting the jar file after deployment. To test the functionality, we could create a simple Fusion Web Application. To add our custom component to the consuming application, we can create a file system connection pointing to the location where the jar file is and add it or, add through the project properties of the ViewController project. Now, our custom component has been added to the consuming application. We could test that by creating a VO in the model project with a query like, select 'Faces' as Name,25 as Weight from dual union all select 'ADF', 15 from dual  union all select 'ADFdi', 30 from dual union all select 'BC4J', 20 from dual union all select 'EJB', 40 from dual union all select 'WS', 35 from dual Add this VO to the AppModule, so that it would be exposed to the data control. Then, we could create a jspx page, and add a tree binding to the VO created. We can now see our Tag Cloud declarative component is available in the component palette.  It can be inserted from the component palette to our page and set it's value property to CollectionModel of the tree binding created. Now that we've created the Declarative component and added that to our page successfully, we can run the page to see how it looks. As per the query, the Tags are displayed in different fonts, based on their weight.

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• Extrapolation breaks collision detection

  - by user22241

  Before applying extrapolation to my sprite's movement, my collision worked perfectly. However, after applying extrapolation to my sprite's movement (to smooth things out), the collision no longer works. This is how things worked before extrapolation: However, after I implement my extrapolation, the collision routine breaks. I am assuming this is because it is acting upon the new coordinate that has been produced by the extrapolation routine (which is situated in my render call ). After I apply my extrapolation How to correct this behaviour? I've tried puting an extra collision check just after extrapolation - this does seem to clear up a lot of the problems but I've ruled this out because putting logic into my rendering is out of the question. I've also tried making a copy of the spritesX position, extrapolating that and drawing using that rather than the original, thus leaving the original intact for the logic to pick up on - this seems a better option, but it still produces some weird effects when colliding with walls. I'm pretty sure this also isn't the correct way to deal with this. I've found a couple of similar questions on here but the answers haven't helped me. This is my extrapolation code: public void onDrawFrame(GL10 gl) { //Set/Re-set loop back to 0 to start counting again loops=0; while(System.currentTimeMillis() > nextGameTick && loops < maxFrameskip){ SceneManager.getInstance().getCurrentScene().updateLogic(); nextGameTick+=skipTicks; timeCorrection += (1000d/ticksPerSecond) % 1; nextGameTick+=timeCorrection; timeCorrection %=1; loops++; tics++; } extrapolation = (float)(System.currentTimeMillis() + skipTicks - nextGameTick) / (float)skipTicks; render(extrapolation); } Applying extrapolation render(float extrapolation){ //This example shows extrapolation for X axis only. Y position (spriteScreenY is assumed to be valid) extrapolatedPosX = spriteGridX+(SpriteXVelocity*dt)*extrapolation; spriteScreenPosX = extrapolationPosX * screenWidth; drawSprite(spriteScreenX, spriteScreenY); } Edit As I mentioned above, I have tried making a copy of the sprite's coordinates specifically to draw with.... this has it's own problems. Firstly, regardless of the copying, when the sprite is moving, it's super-smooth, when it stops, it's wobbling slightly left/right - as it's still extrapolating it's position based on the time. Is this normal behavior and can we 'turn it off' when the sprite stops? I've tried having flags for left / right and only extrapolating if either of these is enabled. I've also tried copying the last and current positions to see if there is any difference. However, as far as collision goes, these don't help. If the user is pressing say, the right button and the sprite is moving right, when it hits a wall, if the user continues to hold the right button down, the sprite will keep animating to the right, while being stopped by the wall (therefore not actually moving), however because the right flag is still set and also because the collision routine is constantly moving the sprite out of the wall, it still appear to the code (not the player) that the sprite is still moving, and therefore extrapolation continues. So what the player would see, is the sprite 'static' (yes, it's animating, but it's not actually moving across the screen), and every now and then it shakes violently as the extrapolation attempts to do it's thing....... Hope this help

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• Animation Trouble with Java Swing Timer - Also, JFrame Will Not Exit_On_Close

  - by forgotton_semicolon

  So, I am using a Java Swing Timer because putting the animation code in a run() method of a Thread subclass caused an insane amount of flickering that is really a terrible experience for any video game player. Can anyone give me any tips on: Why there is no animation... Why the JFrame will not close when it is coded to Exit_On_Close 2 times My code is here: import java.awt.; import java.awt.event.; import javax.swing.*; import java.net.URL; //////////////////////////////////////////////////////////////// TFQ public class TFQ extends JFrame { DrawingsInSpace dis; //========================================================== constructor public TFQ() { dis = new DrawingsInSpace(); JPanel content = new JPanel(); content.setLayout(new FlowLayout()); this.setContentPane(dis); this.setDefaultCloseOperation(EXIT_ON_CLOSE); this.setTitle("Plasma_Orbs_Off_Orion"); this.setSize(500,500); this.pack(); //... Create timer which calls action listener every second.. // Use full package qualification for javax.swing.Timer // to avoid potential conflicts with java.util.Timer. javax.swing.Timer t = new javax.swing.Timer(500, new TimePhaseListener()); t.start(); } /////////////////////////////////////////////// inner class Listener thing class TimePhaseListener implements ActionListener, KeyListener { // counter int total; // loop control boolean Its_a_go = true; //position of our matrix int tf = -400; //sprite directions int Sprite_Direction; final int RIGHT = 1; final int LEFT = 2; //for obstacle Rectangle mega_obstacle = new Rectangle(200, 0, 20, HEIGHT); public void actionPerformed(ActionEvent e) { //... Whenever this is called, repaint the screen dis.repaint(); addKeyListener(this); while (Its_a_go) { try { dis.repaint(); if(Sprite_Direction == RIGHT) { dis.matrix.x += 2; } // end if i think if(Sprite_Direction == LEFT) { dis.matrix.x -= 2; } } catch(Exception ex) { System.out.println(ex); } } // end while i think } // end actionPerformed @Override public void keyPressed(KeyEvent arg0) { // TODO Auto-generated method stub } @Override public void keyReleased(KeyEvent arg0) { // TODO Auto-generated method stub } @Override public void keyTyped(KeyEvent event) { // TODO Auto-generated method stub if (event.getKeyChar()=='f'){ Sprite_Direction = RIGHT; System.out.println("matrix should be animating now "); System.out.println("current matrix position = " + dis.matrix.x); } if (event.getKeyChar()=='d') { Sprite_Direction = LEFT; System.out.println("matrix should be going in reverse"); System.out.println("current matrix position = " + dis.matrix.x); } } } //================================================================= main public static void main(String[] args) { JFrame SafetyPins = new TFQ(); SafetyPins.setVisible(true); SafetyPins.setSize(500,500); SafetyPins.setResizable(true); SafetyPins.setLocationRelativeTo(null); SafetyPins.setDefaultCloseOperation(EXIT_ON_CLOSE); } } class DrawingsInSpace extends JPanel { URL url1_plasma_orbs; URL url2_matrix; Image img1_plasma_orbs; Image img2_matrix; // for the plasma_orbs Rectangle bbb = new Rectangle(0,0, 0, 0); // for the matrix Rectangle matrix = new Rectangle(-400, 60, 430, 200); public DrawingsInSpace() { //load URLs try { url1_plasma_orbs = this.getClass().getResource("plasma_orbs.png"); url2_matrix = this.getClass().getResource("matrix.png"); } catch(Exception e) { System.out.println(e); } // attach the URLs to the images img1_plasma_orbs = Toolkit.getDefaultToolkit().getImage(url1_plasma_orbs); img2_matrix = Toolkit.getDefaultToolkit().getImage(url2_matrix); } public void paintComponent(Graphics g) { super.paintComponent(g); // draw the plasma_orbs g.drawImage(img1_plasma_orbs, bbb.x, bbb.y,this); //draw the matrix g.drawImage(img2_matrix, matrix.x, matrix.y, this); } } // end class enter code here

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• Strategies for invoking subclass methods on generic objects

  - by Brad Patton

  I've run into this issue in a number of places and have solved it a bunch of different ways but looking for other solutions or opinions on how to address. The scenario is when you have a collection of objects all based off of the same superclass but you want to perform certain actions based only on instances of some of the subclasses. One contrived example of this might be an HTML document made up of elements. You could have a superclass named HTMLELement and subclasses of Headings, Paragraphs, Images, Comments, etc. To invoke a common action across all of the objects you declare a virtual method in the superclass and specific implementations in all of the subclasses. So to render the document you could loop all of the different objects in the document and call a common Render() method on each instance. It's the case where again using the same generic objects in the collection I want to perform different actions for instances of specific subclass (or set of subclasses). For example (an remember this is just an example) when iterating over the collection, elements with external links need to be downloaded (e.g. JS, CSS, images) and some might require additional parsing (JS, CSS). What's the best way to handle those special cases. Some of the strategies I've used or seen used include: Virtual methods in the base class. So in the base class you have a virtual LoadExternalContent() method that does nothing and then override it in the specific subclasses that need to implement it. The benefit being that in the calling code there is no object testing you send the same message to each object and let most of them ignore it. Two downsides that I can think of. First it can make the base class very cluttered with methods that have nothing to do with most of the hierarchy. Second it assumes all of the work can be done in the called method and doesn't handle the case where there might be additional context specific actions in the calling code (i.e. you want to do something in the UI and not the model). Have methods on the class to uniquely identify the objects. This could include methods like ClassName() which return a string with the class name or other return values like enums or booleans (IsImage()). The benefit is that the calling code can use if or switch statements to filter objects to perform class specific actions. The downside is that for every new class you need to implement these methods and can look cluttered. Also performance could be less than some of the other options. Use language features to identify objects. This includes reflection and language operators to identify the objects. For example in C# there is the is operator that returns true if the instance matches the specified class. The benefit is no additional code to implement in your object hierarchy. The only downside seems to be the lack of using something like a switch statement and the fact that your calling code is a little more cluttered. Are there other strategies I am missing? Thoughts on best approaches?

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• Deliberate Practice

  - by Jeff Foster

  It’s easy to assume, as software engineers, that there is little need to “practice” writing code. After all, we write code all day long! Just by writing a little each day, we’re constantly learning and getting better, right? Unfortunately, that’s just not true. Of course, developers do improve with experience. Each time we encounter a problem we’re more likely to avoid it next time. If we’re in a team that deploys software early and often, we hone and improve the deployment process each time we practice it. However, not all practice makes perfect. To develop true expertise requires a particular type of practice, deliberate practice, the only goal of which is to make us better programmers. Everyday software development has other constraints and goals, not least the pressure to deliver. We rarely get the chance in the course of a “sprint” to experiment with potential solutions that are outside our current comfort zone. However, if we believe that software is a craft then it’s our duty to strive continuously to raise the standard of software development. This requires specific and sustained efforts to get better at something we currently can’t do well (from Harvard Business Review July/August 2007). One interesting way to introduce deliberate practice, in a sustainable way, is the code kata. The term kata derives from martial arts and refers to a set of movements practiced either solo or in pairs. One of the better-known examples is the Bowling Game kata by Bob Martin, the goal of which is simply to write some code to do the scoring for 10-pin bowling. It sounds too easy, right? What could we possibly learn from such a simple example? Trust me, though, that it’s not as simple as five minutes of typing and a solution. Of course, we can reach a solution in a short time, but the important thing about code katas is that we explore each technique fully and in a controlled way. We tackle the same problem multiple times, using different techniques and making different decisions, understanding the ramifications of each one, and exploring edge cases. The short feedback loop optimizes opportunities to learn. Another good example is Conway’s Game of Life. It’s a simple problem to solve, but try solving it in a functional style. If you’re used to mutability, solving the problem without mutating state will push you outside of your comfort zone. Similarly, if you try to solve it with the focus of “tell-don’t-ask“, how will the responsibilities of each object change? As software engineers, we don’t get enough opportunities to explore new ideas. In the middle of a development cycle, we can’t suddenly start experimenting on the team’s code base. Code katas offer an opportunity to explore new techniques in a safe environment. If you’re still skeptical, my challenge to you is simply to try it out. Convince a willing colleague to pair with you and work through a kata or two. It only takes an hour and I’m willing to bet you learn a few new things each time. The next step is to make it a sustainable team practice. Start with an hour every Friday afternoon (after all who wants to commit code to production just before they leave for the weekend?) for month and see how that works out. Finally, consider signing up for the Global Day of Code Retreat. It’s like a daylong code kata, it’s on December 8th and there’s probably an event in your area!

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• Making AI jump on a spot effectively

  - by Pasquale Sada

  How to calculate, in 3D environment, the closest point, from which an AI character can jump onto a platform? Setup I have an initial velocity V(Vx,Vy,VZ) and a spot where the character stands still at S(Sx,Sy,Sz). What I'm trying to achieve is a successful jump on a spot E(Ex,Ey,Ez) where you have clicked on(only lower or higher spot, because I've in place a simple steering behavior for even terrains). There are no obstacles around. I've implemented a formula that can make him jump in a precise way on a spot but you need to declare an angle: the problem arise when the selected spot is straight above your head. It' pretty lame that the char hang there and can reach a thing that is 1cm above is head. I'll share the code I'm using: Vector3 dir = target - transform.position; // get target direction float h = dir.y; // get height difference dir.y = 0; // retain only the horizontal direction float dist = dir.magnitude ; // get horizontal distance float a = angle * Mathf.Deg2Rad; // convert angle to radians dir.y = dist * Mathf.Tan(a); // set dir to the elevation angle dist += h / Mathf.Tan(a); // correct for small height differences // calculate the velocity magnitude float vel = Mathf.Sqrt(dist * Physics.gravity.magnitude / Mathf.Sin(2 *a)); return vel * dir.normalized; Ended up using the lowest angle (20 degree) and checking for collision on the trajectory. If found any increase the angle. Here some code (to improve the code maybe must stop the check at the highest point of the curve): Vector3 BallisticVel(Vector3 target, float angle) { Vector3 dir = target - transform.position; // get target direction float h = dir.y; // get height difference dir.y = 0; // retain only the horizontal direction float dist = dir.magnitude ; // get horizontal distance float a = angle * Mathf.Deg2Rad; // convert angle to radians dir.y = dist * Mathf.Tan(a); // set dir to the elevation angle dist += h / Mathf.Tan(a); // correct for small height differences // calculate the velocity magnitude float vel = Mathf.Sqrt(dist * Physics.gravity.magnitude / Mathf.Sin(2 * a)); return vel * dir.normalized; } Vector3 TrajectoryPoint(Vector3 startingPosition, Vector3 startingVelocity, float n ) { float t = 1/60 ; // seconds per time step Vector3 stepVelocity = t * startingVelocity; // m/s Vector3 stepGravity = t * t * Physics.gravity; // m/s/s return startingPosition + n * stepVelocity + 0.5f * (n*n+n) * stepGravity; } bool CheckTrajectory(Vector3 startingPosition,Vector3 target, float angle_jump) { Debug.Log("checking"); if(angle_jump < 80f) { Debug.Log("if"); Vector3 startingVelocity = BallisticVel(target, angle_jump); for (int i = 0; i < 180; i++) { //Debug.Log(i); Vector3 trajectoryPosition = TrajectoryPoint( startingPosition, startingVelocity, i ); if(Physics.Raycast(trajectoryPosition,Vector3.forward,safeDistance)) { angle_jump += 10; break; // restart loop with the new angle } else continue; } return true; JumpVelocity = BallisticVel(target, angle_jump); } return false; }

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• Antenna Aligner Part 4: Role'ing in the deep

  - by Chris George

  Since last time I've been trying to sort out the general workflow of the app. It's fundamentally not hard, there is a list of transmitters, you select a transmitter and it shows the compass view. Having done quite a bit of ajax/asp.net/html in the past, I immediately started off by creating two divs within my 'page', one for the list, one for the compass. Then using the onClick event in the list, this will switch the display attribute on the divs. This seemed to work, but did lead to some dodgy transitional redrawing artefacts which I was not happy with. So after some Googling I realised I was doing it all wrong! JQuery mobile has the concept of giving an object in html a data-role. By giving a div the attribute data-role="page" it is then treated as a separate page on the mobile device. Within the code, this is referenced like a html anchor in the form #mypage. Using this system, page transitions such as fade or slide are automatically applied which adds to the whole authenticity of the app! Here is a simple example: . <a href="#'compasspage">compass</a> . <div data-role="page" id="compasspage" data-add-back-btn="true"> But I don't want just a static link, I want to dynamically create my list, and get each list elements to switch to the compass page with the right information. So here is the jquery that I used to dynamically inject new <li> rows into the <ul> block. $('ul').append($('<li/>', {    //here appendin `<li>`     'data-role': "list-divider" }).append($('<a/>', {    //here appending `<a>` into `<li>`     'href': '#compasspage',     'data-transition': 'none',     'onclick': 'selectTx(' + i + ')',     'html': buttonHtml }))); $('ul').listview('refresh'); This is called within a for loop so the first 5 appropriate transmitters are used. There are several things of interest to note here. Firstly, I could not find a more elegant way to tell the target page which transmitter I've clicked on, so I have used the onclick event as well as the href attribute. The onclick event fires 'selectTx' which simply sets a global member variable to the specific index number I've clicked on. Yes it's not nice, but it works. Secondly, the data-transition attribute is set to 'none'. I wanted the transition between the pages to be a whooshy slidey effect. However this worked going to the compass page, but returning to the list page gave some undesirable visual artefacts (flickering, redrawing etc.). So I decided to remove the transitions all together, which was a shame. Thirdly, rather than embedding loads of html into the append command, I removed this out into a variable 'buttonHtml'. Doing this really tidied up my code. Until next time!

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• libgdx draw issue and animation

  - by johnny-b

  it seems as though i cannot get the draw method to work??? it seems as though the bullet.draw(batcher) does not work and i cannot understand why as the bullet is a sprite. i have made a Sprite[] and added them as animation. could that be it? i tried batcher.draw(AssetLoader.bulletAnimation.getKeyFrame(runTime), bullet.getX(), bullet.getY(), bullet.getOriginX() / 2, bullet.getOriginY() / 2, bullet.getWidth(), bullet.getHeight(), 1, 1, bullet.getRotation()); but that dont work, the only way it draws is this batcher.draw(AssetLoader.bulletAnimation.getKeyFrame(runTime), bullet.getX(), bullet.getY()); below is the code. // this is in a Asset Class texture = new Texture(Gdx.files.internal("SpriteN1.png")); texture.setFilter(TextureFilter.Nearest, TextureFilter.Nearest); bullet1 = new Sprite(texture, 380, 350, 45, 20); bullet1.flip(false, true); bullet2 = new Sprite(texture, 425, 350, 45, 20); bullet2.flip(false, true); Sprite[] bullets = { bullet1, bullet2 }; bulletAnimation = new Animation(0.06f, bullets); bulletAnimation.setPlayMode(Animation.PlayMode.LOOP); // this is the GameRender class public class GameRender() { private Bullet bullet; private Ball ball; public GameRenderer(GameWorld world) { myWorld = world; cam = new OrthographicCamera(); cam.setToOrtho(true, 480, 320); batcher = new SpriteBatch(); // Attach batcher to camera batcher.setProjectionMatrix(cam.combined); shapeRenderer = new ShapeRenderer(); shapeRenderer.setProjectionMatrix(cam.combined); // Call helper methods to initialize instance variables initGameObjects(); initAssets(); } private void initGameObjects() { ball = GameWorld.getBall(); bullet = myWorld.getBullet(); scroller = myWorld.getScroller(); } private void initAssets() { ballAnimation = AssetLoader.ballAnimation; bulletAnimation = AssetLoader.bulletAnimation; } public void render(float runTime) { Gdx.gl.glClearColor(0, 0, 0, 1); Gdx.gl.glClear(GL30.GL_COLOR_BUFFER_BIT); batcher.begin(); // Disable transparency // This is good for performance when drawing images that do not require // transparency. batcher.disableBlending(); // The ball needs transparency, so we enable that again. batcher.enableBlending(); batcher.draw(AssetLoader.ballAnimation.getKeyFrame(runTime), ball.getX(), ball.getY(), ball.getWidth(), ball.getHeight()); batcher.draw(AssetLoader.bulletAnimation.getKeyFrame(runTime), bullet.getX(), bullet.getY()); // End SpriteBatch batcher.end(); } } // this is the gameworld class public class GameWorld { public static Ball ball; private Bullet bullet; private ScrollHandler scroller; public GameWorld() { ball = new Ball(480, 273, 32, 32); bullet = new Bullet(10, 10); scroller = new ScrollHandler(0); } public void update(float delta) { ball.update(delta); bullet.update(delta); scroller.update(delta); } public static Ball getBall() { return ball; } public ScrollHandler getScroller() { return scroller; } public Bullet getBullet() { return bullet; } } is there anyway so make the sprite work?

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• Introduction to WebCenter Personalization: &ldquo;The Conductor&rdquo;

  - by Steve Pepper

  There are some new faces in the town of WebCenter with the latest 11g PS3 release.  A new component has introduced itself as "Oracle WebCenter Personalization", a.k.a WCP, to simplify delivery of a personalized experience and content to end users.  This posting reviews one of the primary components within WCP: "The Conductor". The Conductor: This ain't just an ordinary cloud... One of the founding principals behind WebCenter Personalization was to provide an open client-side API that remains independent of the technology invoking it, in addition to independence from the architecture running it.  The Conductor delivers this, and much, much more. The Conductor is the engine behind WebCenter Personalization that allows flow-based documents, called "Scenarios", to be managed and executed on the server-side through a well published and RESTful api.      The Conductor also supports an extensible model for custom provider integration that can be easily invoked within a Scenario to promote seamless integration with existing business assets. Introducing the Scenario Conductor Scenarios are declarative offline-authored documents using the custom Personalization JDeveloper bundle included with WebCenter.  A Scenario contains one (or more) statements that can: Create variables that are scoped to the current execution context Iterate over collections, or loop until a specific condition is met Execute one or more statements when a condition is met Invoke other scenarios that exist within the same namespace Invoke a data provider that integrates with custom applications Once a variable is assigned within the Scenario's execution context, it can be referenced anywhere within the same Scenario using the common Expression Language syntax used in J2EE web containers. Scenarios are then published and tested to the Integrated WebLogic Server domain, or published remotely to other domains running WebCenter Personalization. Various Client-side Models The Conductor server API is built upon RESTful services that support a wide variety of clients able to communicate over HTTP.  The Conductor supports the following client-side models: REST:  Popular browser-based languages can be used to manage and execute Conductor Scenarios.  There are other public methods to retrieve configured provider metadata that can be used by custom applications. The Conductor currently supports XML and JSON for it's API syntax. Java: WebCenter Personalization delivers a robust and light-weight java client with the popular Jersey framework as it's foundation.  It has never been easier to write a remote java client to manage remote RESTful services. Expression Language (EL): Allow the results of Scenario execution to control your user interface or embed personalized content using the session-scoped managed bean.  The EL client can also be used in straight JSP pages with minimal configuration. Extensible Provider Framework The Conductor supports a pluggable provider framework for integrating custom code with Scenario execution.  There are two types of providers supported by the Conductor: Function Provider: Function Providers are simple java annotated classes with static methods that are meant to be served as utilities.  Some common uses would include: object creation or instantiation, data transformation, and the like.  Function Providers can be invoked using the common EL syntax from variable assignments, conditions, and loops. For example:  ${myUtilityClass:doStuff(arg1,arg2))} If you are familiar with EL Functions, Function Providers are based on the same concept. Data Provider: Like Function Providers, Data Providers are annotated java classes, but they must adhere to a much more strict object model.  Data Providers have access to a wealth of Conductor services, such as: Access to namespace-scoped configuration API that can be managed by Oracle Enterprise Manager, Scenario execution context for expression resolution, and more.  Oracle ships with three out-of-the-box data providers that supports integration with: Standardized Content Servers(CMIS),  Federated Profile Properties through the Properties Service, and WebCenter Activity Graph. Useful References If you are looking to immediately get started writing your own application using WebCenter Personalization Services, you will find the following references helpful in getting you on your way: Personalizing WebCenter Applications Authoring Personalized Scenarios in JDeveloper Using Personalization APIs Externally Implementing and Calling Function Providers Implementing and Calling Data Providers

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• Multithreading 2D gravity calculations

  - by Postman

  I'm building a space exploration game and I've currently started working on gravity ( In C# with XNA). The gravity still needs tweaking, but before I can do that, I need to address some performance issues with my physics calculations. This is using 100 objects, normally rendering 1000 of them with no physics calculations gets well over 300 FPS (which is my FPS cap), but any more than 10 or so objects brings the game (and the single thread it runs on) to its knees when doing physics calculations. I checked my thread usage and the first thread was killing itself from all the work, so I figured I just needed to do the physics calculation on another thread. However when I try to run the Gravity.cs class's Update method on another thread, even if Gravity's Update method has nothing in it, the game is still down to 2 FPS. Gravity.cs public void Update() { foreach (KeyValuePair<string, Entity> e in entityEngine.Entities) { Vector2 Force = new Vector2(); foreach (KeyValuePair<string, Entity> e2 in entityEngine.Entities) { if (e2.Key != e.Key) { float distance = Vector2.Distance(entityEngine.Entities[e.Key].Position, entityEngine.Entities[e2.Key].Position); if (distance > (entityEngine.Entities[e.Key].Texture.Width / 2 + entityEngine.Entities[e2.Key].Texture.Width / 2)) { double angle = Math.Atan2(entityEngine.Entities[e2.Key].Position.Y - entityEngine.Entities[e.Key].Position.Y, entityEngine.Entities[e2.Key].Position.X - entityEngine.Entities[e.Key].Position.X); float mult = 0.1f * (entityEngine.Entities[e.Key].Mass * entityEngine.Entities[e2.Key].Mass) / distance * distance; Vector2 VecForce = new Vector2((float)Math.Cos(angle), (float)Math.Sin(angle)); VecForce.Normalize(); Force = Vector2.Add(Force, VecForce * mult); } } } entityEngine.Entities[e.Key].Position += Force; } } Yeah, I know. It's a nested foreach loop, but I don't know how else to do the gravity calculation, and this seems to work, it's just so intensive that it needs its own thread. (Even if someone knows a super efficient way to do these calculations, I'd still like to know how I COULD do it on multiple threads instead) EntityEngine.cs (manages an instance of Gravity.cs) public class EntityEngine { public Dictionary<string, Entity> Entities = new Dictionary<string, Entity>(); public Gravity gravity; private Thread T; public EntityEngine() { gravity = new Gravity(this); } public void Update() { foreach (KeyValuePair<string, Entity> e in Entities) { Entities[e.Key].Update(); } T = new Thread(new ThreadStart(gravity.Update)); T.IsBackground = true; T.Start(); } } EntityEngine is created in Game1.cs, and its Update() method is called within Game1.cs. I need my physics calculation in Gravity.cs to run every time the game updates, in a separate thread so that the calculation doesn't slow the game down to horribly low (0-2) FPS. How would I go about making this threading work? (any suggestions for an improved Planetary Gravity system are welcome if anyone has them) I'm also not looking for a lesson in why I shouldn't use threading or the dangers of using it incorrectly, I'm looking for a straight answer on how to do it. I've already spent an hour googling this very question with little results that I understood or were helpful. I don't mean to come off rude, but it always seems hard as a programming noob to get a straight meaningful answer, I usually rather get an answer so complex I'd easily be able to solve my issue if I understood it, or someone saying why I shouldn't do what I want to do and offering no alternatives (that are helpful). Thank you for the help!

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• Non-blocking I/O using Servlet 3.1: Scalable applications using Java EE 7 (TOTD #188)

  - by arungupta

  Servlet 3.0 allowed asynchronous request processing but only traditional I/O was permitted. This can restrict scalability of your applications. In a typical application, ServletInputStream is read in a while loop. public class TestServlet extends HttpServlet {    protected void doGet(HttpServletRequest request, HttpServletResponse response)         throws IOException, ServletException {     ServletInputStream input = request.getInputStream();       byte[] b = new byte[1024];       int len = -1;       while ((len = input.read(b)) != -1) {          . . .        }   }} If the incoming data is blocking or streamed slower than the server can read then the server thread is waiting for that data. The same can happen if the data is written to ServletOutputStream. This is resolved in Servet 3.1 (JSR 340, to be released as part Java EE 7) by adding event listeners - ReadListener and WriteListener interfaces. These are then registered using ServletInputStream.setReadListener and ServletOutputStream.setWriteListener. The listeners have callback methods that are invoked when the content is available to be read or can be written without blocking. The updated doGet in our case will look like: AsyncContext context = request.startAsync();ServletInputStream input = request.getInputStream();input.setReadListener(new MyReadListener(input, context)); Invoking setXXXListener methods indicate that non-blocking I/O is used instead of the traditional I/O. At most one ReadListener can be registered on ServletIntputStream and similarly at most one WriteListener can be registered on ServletOutputStream. ServletInputStream.isReady and ServletInputStream.isFinished are new methods to check the status of non-blocking I/O read. ServletOutputStream.canWrite is a new method to check if data can be written without blocking.  MyReadListener implementation looks like: @Overridepublic void onDataAvailable() { try { StringBuilder sb = new StringBuilder(); int len = -1; byte b[] = new byte[1024]; while (input.isReady() && (len = input.read(b)) != -1) { String data = new String(b, 0, len); System.out.println("--> " + data); } } catch (IOException ex) { Logger.getLogger(MyReadListener.class.getName()).log(Level.SEVERE, null, ex); }}@Overridepublic void onAllDataRead() { System.out.println("onAllDataRead"); context.complete();}@Overridepublic void onError(Throwable t) { t.printStackTrace(); context.complete();} This implementation has three callbacks: onDataAvailable callback method is called whenever data can be read without blocking onAllDataRead callback method is invoked data for the current request is completely read. onError callback is invoked if there is an error processing the request. Notice, context.complete() is called in onAllDataRead and onError to signal the completion of data read. For now, the first chunk of available data need to be read in the doGet or service method of the Servlet. Rest of the data can be read in a non-blocking way using ReadListener after that. This is going to get cleaned up where all data read can happen in ReadListener only. The sample explained above can be downloaded from here and works with GlassFish 4.0 build 64 and onwards. The slides and a complete re-run of What's new in Servlet 3.1: An Overview session at JavaOne is available here. Here are some more references for you: Java EE 7 Specification Status Servlet Specification Project JSR Expert Group Discussion Archive Servlet 3.1 Javadocs

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• Bowing to User Experience

  As a consumer of geeky news it is hard to check my Google Reader without running into two or three posts about Apples iPad and in particular the changes to the developer guidelines which seemingly restrict developers to using Apples Xcode tool and Objective-C language for iPad apps. One of the alternatives to Objective-C affected, is MonoTouch, an option with some appeal to me as it is based on the Mono implementation of C#. Seemingly restricted is the key word here, as far as I can tell, no official announcement has been made about its fate. For more details around MonoTouch for iPhone OS, check out Miguel de Icazas post: http://tirania.org/blog/archive/2010/Apr-28.html. These restrictions have provoked some outrage as the perception is that Apple is arrogantly restricting developers freedom to create applications as they choose and perhaps unwittingly shortchanging iPhone/iPad users who wont benefit from these now never-to-be-made great applications. Apples response has mostly been to say they are concentrating on providing a certain user experience to their customers, and to do this, they insist everyone uses the tools they approve. Which isnt a surprising line of reasoning given Apple restricts the hardware used and content of the apps already. The vogue term for this approach is curated, as in a benevolent museum director selecting only the finest artifacts for display or a wise gardener arranging the plants in a garden just so. If this is what a curated experience is like it is hard to argue that consumers are not responding. My iPhone is probably the most satisfying piece of technology I own. Coming from the Razr, it really was an revolution in how the form factor, interface and user experience all tied together. While the curated approach reinvented the smart phone genre, it is easy to forget that this is not a new approach for Apple. Macbooks and Macs are Apple hardware that run Apple software. And theyve been successful, but not quite in the same way as the iPhone or iPad (based on early indications). Why not? Well a curated approach can only be wildly successful if the curator a) makes the right choices and b) offers choices that no one else has. Although its advantages are eroding, the iPhone was different from other phones, a unique, focused, touch-centric experience. The iPad is an attempt to define another category of computing. Macs and Macbooks are great devices, but are not fundamentally a different user experience than a PC, you still have windows, file folders, mouse and keyboard, and similar applications. So the big question for Apple is can they hold on to their market advantage, continuing innovating in user experience and stay on top? Or are they going be like Xerox, and the rest of the world says thank you for the windows metaphor, now let me implement that better? It will be exciting to watch, with Android already a viable competitor and Microsoft readying Windows Phone 7. And to close the loop back to the restrictions on developing for iPhone OS. At this point the main target appears to be Adobe and Adobe Flash. Apples calculation is that a) they dont need those developers or b) the developers they want will learn Apples stuff anyway. My guess is that they are correct; that as much as I like the idea of developers having more options, I am not going to buy a competitors product to spite Apple unless that product is just as usable. For a non-technical consumer, I dont know that this conversation even factors into the buying decision. If it did, wed be talking about how Microsoft is trying to retake a slice of market share from the behemoth that is Linux.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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• Creating a voxel world with 3D arrays using threads

  - by Sean M.

  I am making a voxel game (a bit like Minecraft) in C++(11), and I've come across an issue with creating a world efficiently. In my program, I have a World class, which holds a 3D array of Region class pointers. When I initialize the world, I give it a width, height, and depth so it knows how large of a world to create. Each Region is split up into a 32x32x32 area of blocks, so as you may guess, it takes a while to initialize the world once the world gets to be above 8x4x8 Regions. In order to alleviate this issue, I thought that using threads to generate different levels of the world concurrently would make it go faster. Having not used threads much before this, and being still relatively new to C++, I'm not entirely sure how to go about implementing one thread per level (level being a xz plane with a height of 1), when there is a variable number of levels. I tried this: for(int i = 0; i < height; i++) { std::thread th(std::bind(&World::load, this, width, height, depth)); th.join(); } Where load() just loads all Regions at height "height". But that executes the threads one at a time (which makes sense, looking back), and that of course takes as long as generating all Regions in one loop. I then tried: std::thread t1(std::bind(&World::load, this, w, h1, h2 - 1, d)); std::thread t2(std::bind(&World::load, this, w, h2, h3 - 1, d)); std::thread t3(std::bind(&World::load, this, w, h3, h4 - 1, d)); std::thread t4(std::bind(&World::load, this, w, h4, h - 1, d)); t1.join(); t2.join(); t3.join(); t4.join(); This works in that the world loads about 3-3.5 times faster, but this forces the height to be a multiple of 4, and it also gives the same exact VAO object to every single Region, which need individual VAOs in order to render properly. The VAO of each Region is set in the constructor, so I'm assuming that somehow the VAO number is not thread safe or something (again, unfamiliar with threads). So basically, my question is two one-part: How to I implement a variable number of threads that all execute at the same time, and force the main thread to wait for them using join() without stopping the other threads? How do I make the VAO objects thread safe, so when a bunch of Regions are being created at the same time across multiple threads, they don't all get the exact same VAO? Turns out it has to do with GL contexts not working across multiple threads. I moved the VAO/VBO creation back to the main thread. Fixed! Here is the code for block.h/.cpp, region.h/.cpp, and CVBObject.h/.cpp which controls VBOs and VAOs, in case you need it. If you need to see anything else just ask. EDIT: Also, I'd prefer not to have answers that are like "you should have used boost". I'm trying to do this without boost to get used to threads before moving onto other libraries.

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• Class design issue

  - by user2865206

  I'm new to OOP and a lot of times I become stumped in situations similar to this example: Task: Generate an XML document that contains information about a person. Assume the information is readily available in a database. Here is an example of the structure: <Person> <Name>John Doe</Name> <Age>21</Age> <Address> <Street>100 Main St.</Street> <City>Sylvania</City> <State>OH</State> </Address> <Relatives> <Parents> <Mother> <Name>Jane Doe</Name> </Mother> <Father> <Name>John Doe Sr.</Name> </Father> </Parents> <Siblings> <Brother> <Name>Jeff Doe</Name> </Brother> <Brother> <Name>Steven Doe</Name> </Brother> </Siblings> </Relatives> </Person> Ok lets create a class for each tag (ie: Person, Name, Age, Address) Lets assume each class is only responsible for itself and the elements directly contained Each class will know (have defined by default) the classes that are directly contained within them Each class will have a process() function that will add itself and its childeren to the XML document we are creating When a child is drawn, as in the previous line, we will have them call process() as well Now we are in a recursive loop where each object draws their childeren until all are drawn But what if only some of the tags need to be drawn, and the rest are optional? Some are optional based on if the data exists (if we have it, we must draw it), and some are optional based on the preferences of the user generating the document How do we make sure each object has the data it needs to draw itself and it's childeren? We can pass down a massive array through every object, but that seems shitty doesnt it? We could have each object query the database for it, but thats a lot of queries, and how does it know what it's query is? What if we want to get rid of a tag later? There is no way to reference them. I've been thinking about this for 20 hours now. I feel like I am misunderstanding a design principle or am just approaching this all wrong. How would you go about programming something like this? I suppose this problem could apply to any senario where there are classes that create other classes, but the classes created need information to run. How do I get the information to them in a way that doesn't seem fucky? Thanks for all of your time, this has been kicking my ass.

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• Intern Screening - Software 'Quiz'

  - by Jeremy1026

  I am in charge of selecting a new software development intern for a company that I work with. I wanted to throw a little 'quiz' at the applicants before moving forth with interviews so as to weed out the group a little bit to find some people that can demonstrate some skill. I put together the following quiz to send to applicants, it focuses only on PHP, but that is because that is what about 95% of the work will be done in. I'm hoping to get some feedback on A. if its a good idea to send this to applicants and B. if it can be improved upon. # 1. FizzBuzz # Write a small application that does the following: # Counts from 1 to 100 # For multiples of 3 output "Fizz" # For multiples of 5 output "Buzz" # For multiples of 3 and 5 output "FizzBuzz" # For numbers that are not multiples of 3 nor 5 output the number. <?php ?> # 2. Arrays # Create a multi-dimensional array that contains # keys for 'id', 'lot', 'car_model', 'color', 'price'. # Insert three sets of data into the array. <?php ?> # 3. Comparisons # Without executing the code, tell if the expressions # below will return true or false. <?php if ((strpos("a","abcdefg")) == TRUE) echo "True"; else echo "False"; //True or False? if ((012 / 4) == 3) echo "True"; else echo "False"; //True or False? if (strcasecmp("abc","ABC") == 0) echo "True"; else echo "False"; //True or False? ?> # 4. Bug Checking # The code below is flawed. Fix it so that the code # runs properly without producing any Errors, Warnings # or Notices, and returns the proper value. <?php //Determine how many parts are needed to create a 3D pyramid. function find_3d_pyramid($rows) { //Loop through each row. for ($i = 0; $i < $rows; $i++) { $lastRow++; //Append the latest row to the running total. $total = $total + (pow($lastRow,3)); } //Return the total. return $total; } $i = 3; echo "A pyramid consisting of $i rows will have a total of ".find_3d_pyramid($i)." pieces."; ?> # 5. Quick Examples # Create a small example to complete the task # for each of the following problems. # Create an md5 hash of "Hello World"; # Replace all occurances of "_" with "-" in the string "Welcome_to_the_universe." # Get the current date and time, in the following format, YYYY/MM/DD HH:MM:SS AM/PM # Find the sum, average, and median of the following set of numbers. 1, 3, 5, 6, 7, 9, 10. # Randomly roll a six-sided die 5 times. Store the 5 rolls into an array. <?php ?>

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• Resolving collisions between dynamic game objects

  - by TheBroodian

  I've been building a 2D platformer for some time now, I'm getting to the point where I am adding dynamic objects to the stage for testing. This has prompted me to consider how I would like my character and other objects to behave when they collide. A typical staple in many 2D platformer type games is that the player takes damage upon touching an enemy, and then essentially becomes able to pass through enemies during a period of invulnerability, and at the same time, enemies are able to pass through eachother freely. I personally don't want to take this approach, it feels strange to me that the player should receive arbitrary damage for harmless contact to an enemy, despite whether the enemy is attacking or not, and I would like my enemies' interactions between each other (and my player) to be a little more organic, so to speak. In my head I sort of have this idea where a game object (player, or non player) would be able to push other game objects around by manner of 'pushing' each other out of one anothers' bounding boxes if there is an intersection, and maybe correlate the repelling force to how much their bounding boxes are intersecting. The problem I'm experiencing is I have no idea what the math might look like for something like this? I'll show what work I've done so far, it sort of works, but it's jittery, and generally not quite what I would pass in a functional game: //Clears the anti-duplicate buffer collisionRecord.Clear(); //pick a thing foreach (GameObject entity in entities) { //pick another thing foreach (GameObject subject in entities) { //check to make sure both things aren't the same thing if (!ReferenceEquals(entity, subject)) { //check to see if thing2 is in semi-near proximity to thing1 if (entity.WideProximityArea.Intersects(subject.CollisionRectangle) || entity.WideProximityArea.Contains(subject.CollisionRectangle)) { //check to see if thing2 and thing1 are colliding. if (entity.CollisionRectangle.Intersects(subject.CollisionRectangle) || entity.CollisionRectangle.Contains(subject.CollisionRectangle) || subject.CollisionRectangle.Contains(entity.CollisionRectangle)) { //check if we've already resolved their collision or not. if (!collisionRecord.ContainsKey(entity.GetHashCode())) { //more duplicate resolution checking. if (!collisionRecord.ContainsKey(subject.GetHashCode())) { //if thing1 is traveling right... if (entity.Velocity.X > 0) { //if it isn't too far to the right... if (subject.CollisionRectangle.Contains(new Microsoft.Xna.Framework.Rectangle(entity.CollisionRectangle.Right, entity.CollisionRectangle.Y, 1, entity.CollisionRectangle.Height)) || subject.CollisionRectangle.Intersects(new Microsoft.Xna.Framework.Rectangle(entity.CollisionRectangle.Right, entity.CollisionRectangle.Y, 1, entity.CollisionRectangle.Height))) { //Find how deep thing1 is intersecting thing2's collision box; float offset = entity.CollisionRectangle.Right - subject.CollisionRectangle.Left; //Move both things in opposite directions half the length of the intersection, pushing thing1 to the left, and thing2 to the right. entity.Velocities.Add(new Vector2(-(((offset * 4) * (float)gameTime.ElapsedGameTime.TotalMilliseconds)), 0)); subject.Velocities.Add(new Vector2((((offset * 4) * (float)gameTime.ElapsedGameTime.TotalMilliseconds)), 0)); } } //if thing1 is traveling left... if (entity.Velocity.X < 0) { //if thing1 isn't too far left... if (entity.CollisionRectangle.Contains(new Microsoft.Xna.Framework.Rectangle(subject.CollisionRectangle.Right, subject.CollisionRectangle.Y, 1, subject.CollisionRectangle.Height)) || entity.CollisionRectangle.Intersects(new Microsoft.Xna.Framework.Rectangle(subject.CollisionRectangle.Right, subject.CollisionRectangle.Y, 1, subject.CollisionRectangle.Height))) { //Find how deep thing1 is intersecting thing2's collision box; float offset = subject.CollisionRectangle.Right - entity.CollisionRectangle.Left; //Move both things in opposite directions half the length of the intersection, pushing thing1 to the right, and thing2 to the left. entity.Velocities.Add(new Vector2((((offset * 4) * (float)gameTime.ElapsedGameTime.TotalMilliseconds)), 0)); subject.Velocities.Add(new Vector2(-(((offset * 4) * (float)gameTime.ElapsedGameTime.TotalMilliseconds)), 0)); } } //Make record that thing1 and thing2 have interacted and the collision has been solved, so that if thing2 is picked next in the foreach loop, it isn't checked against thing1 a second time before the next update. collisionRecord.Add(entity.GetHashCode(), subject.GetHashCode()); } } } } } } } } One of the biggest issues with my code aside from the jitteriness is that if one character were to land on top of another character, it very suddenly and abruptly resolves the collision, whereas I would like a more subtle and gradual resolution. Any thoughts or ideas are incredibly welcome and helpful.

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• Application using JOGL stays in Limbo when closing

  - by Roy T.

  I'm writing a game using Java and OpenGL using the JOGL bindings. I noticed that my game doesn't terminate properly when closing the window even though I've set the closing operation of the JFrame to EXIT_ON_CLOSE. I couldn't track down where the problem was so I've made a small reproduction case. Note that on some computers the program terminates normally when closing the window but on other computers (notably my own) something in the JVM keeps lingering, this causes the JFrame to never be disposed and the application to never exit. I haven't found something in common between the computers that had difficulty terminating. All computers had Windows 7, Java 7 and the same version of JOGL and some terminated normally while others had this problem. The test case is as follows: public class App extends JFrame implements GLEventListener { private GLCanvas canvas; @Override public void display(GLAutoDrawable drawable) { GL3 gl = drawable.getGL().getGL3(); gl.glClearColor(0.0f, 0.0f, 0.0f, 0.0f); gl.glClear(GL3.GL_COLOR_BUFFER_BIT); gl.glFlush(); } // The overrides for dispose (the OpenGL one), init and reshape are empty public App(String title, boolean full_screen, int width, int height) { //snipped setting the width and height of the JFRAME GLProfile profile = GLProfile.get(GLProfile.GL3); GLCapabilities capabilities = new GLCapabilities(profile); canvas = new GLCanvas(capabilities); canvas.addGLEventListener(this); canvas.setSize(getWidth(), getHeight()); add(canvas); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //!!! setVisible(true); } @Override public void dispose() { System.out.println("HELP"); // } public static void main( String[] args ) { new App("gltut 01", false, 1280, 720); } } As you can see this doesn't do much more than adding a GLCanvas to the frame and registering the main class as the GLEventListener. So what keeps lingering? I'm not sure. I've made some screenshots. The application running normally. The application after the JFrame is closed, note that the JVM still hasn't exited or printed a return code. The application after it was force closed. Note the return code -1, so it wasnt just the JVM standing by or something the application really hadn't exited yet. So what is keeping the application in Limbo? Might it be the circular reference between the GLCanvas and the JFrame? I thought the GC could figure that out. If so how should I deal with that when I want to exit? Is there any other clean-up required when using JOGL? I've tried searching but it doesn't seem to be necessary. Edit, to clarify: there are 2 dispose functions dispose(GLAutoDrawable arg) which is a member of GLEventListener and dispose() which is a member of JFrame. The first one is called correctly (but I wouldn't know what to there, destroying the GLAutoDrawable or the GLCanvas gives an infinite exception loop) the second one is never called.

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• Why does OpenGL seem to ignore my glBindTexture call?

  - by Killrazor

  I'm having problems making a simple sprite rendering. I load 2 different textures. Then, I bind these textures and draw 2 squares, one with each texture. But only the texture of the first rendered object is drawn in both squares. Its like if I'd only use a texture or as if glBindTexture don't work properly. I know that GL is a state machine, but I think that you only need to change active texture with glBindTexture. I load texture with this method: bool CTexture::generate( utils::CImageBuff* img ) { assert(img); m_image = img; CHECKGL(glGenTextures(1,&m_textureID)); CHECKGL(glBindTexture(GL_TEXTURE_2D,m_textureID)); CHECKGL(glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR)); CHECKGL(glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR)); //CHECKGL(glTexImage2D(GL_TEXTURE_2D,0,img->getBpp(),img->getWitdh(),img->getHeight(),0,img->getFormat(),GL_UNSIGNED_BYTE,img->getImgData())); CHECKGL(glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, img->getWitdh(), img->getHeight(), 0, GL_RGBA, GL_UNSIGNED_BYTE, img->getImgData())); return true; } And I bind textures with this function: void CTexture::bind() { CHECKGL(glBindTexture(GL_TEXTURE_2D,m_textureID)); } Also, I draw sprites with this method void CSprite2D::render() { CHECKGL(glLoadIdentity()); CHECKGL(glEnable(GL_TEXTURE_2D)); CHECKGL(glEnable(GL_BLEND)); CHECKGL(glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)); m_texture->bind(); CHECKGL(glPushMatrix()); CHECKGL(glBegin(GL_QUADS)); CHECKGL(glTexCoord2f(m_textureAreaStart.s,m_textureAreaStart.t)); // 0,0 by default CHECKGL(glVertex3i(m_position.x,m_position.y,0)); CHECKGL(glTexCoord2f(m_textureAreaEnd.s,m_textureAreaStart.t)); // 1,0 by default CHECKGL(glVertex3i( m_position.x + m_dimensions.x, m_position.y, 0)); CHECKGL(glTexCoord2f(m_textureAreaEnd.s, m_textureAreaEnd.t)); // 1,1 by default CHECKGL(glVertex3i( m_position.x + m_dimensions.x, m_position.y + m_dimensions.y, 0)); CHECKGL(glTexCoord2f(m_textureAreaStart.s, m_textureAreaEnd.t)); // 0,1 by default CHECKGL(glVertex3i( m_position.x, m_position.y + m_dimensions.y,0)); CHECKGL(glPopMatrix()); CHECKGL(glDisable(GL_BLEND)); } Edit: I bring also the check error code: int CheckGLError(const char *GLcall, const char *file, int line) { GLenum errCode; //avoids infinite loop int errorCount = 0; while ( (errCode=glGetError()) != GL_NO_ERROR && ++errorCount < 3000) { utils::globalLogPtr log = utils::CGLogFactory::getLogInstance(); const GLubyte *errString; errString = gluErrorString(errCode); std::stringstream ss; ss << "In "<< __FILE__<<"("<< __LINE__<<") "<<"GL error with code: " << errCode<<" at file " << file << ", line " << line << " with message: " << errString << "\n"; log->addMessage(ss.str(),ZEL_APPENDER_GL,utils::LOGLEVEL_ERROR); } return 0; }

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• Making user input/math on data fast, unlike excel type programs

  - by proGrammar

  I'm creating a research platform solely for myself to do some research on data. Programs like excel are terribly slow for me so I'm trying to come up with another solution. Originally I used excel. A1 was the cell that contained the data and all other cells in use calculated something on A1, or on other cells, that all could be in the end traced to A1. A1 was like an element of an array, I then I incremented it to go through all my data. This was way too slow. So the only other option I found originally was to hand code in c# the calculations inside a loop. Then I simply recompiled each time I changed my math. This was terribly slow to do and I had to order everything correctly so things would update correctly (dependencies). I could have also used events, but hand coding events for each cell like calculation would also be very slow. Next I created an application to read Excel and to perfectly imitate it. Which is what I now use. Basically I write formulas onto a fraction of my data to get live results inside excel. Then my program reads excel, writes another c# program, compiles it, and runs that program which runs my excel created formulas through a lot more data a whole lot faster. The advantage being my application dependency sorts everything (or I could use events) so I don't have to (like excel does) And of course the speed. But now its not a single application anymore. Instead its 2 applications, one which only reads my formulas and writes another program. The other one being the result which only lives for a short while before I do other runs through my data with different formulas / settings. So I can't see multiple results at one time without introducing even more programs like a database or at least having the 2 applications talking to each other. My idea was to have a dll that would be written, compiled, loaded, and unloaded again and again. So a self-updating program, sort of. But apparently that's not possible without another appdomain which means data has to be marshaled to be moved between the appdomains. Which would slow things down, not for summaries, but for other stuff I need to do with all my data. I'm also forgetting to mention a huge problem with restarting an application again and again which is having to reload ALL my data into memory again and again. But its still a whole lot faster than excel. I'm really super puzzled as to what people do when they want to research data fast. I'm completely unable to have a program accept user input and having it fast. My understanding is that it would have to do things like excel which is to evaluate strings again and again. So my only option is to repeatedly compile applications. Do I have a correct understanding on computer science? I've only just began programming, and didn't think I would have to learn much to do some simple math on data. My understanding is its either compiling my user defined stuff to a program or evaluating them from a string or something stupid again and again. And my only option is to probably switch operating systems or something to be able to have a program compile and run itself without stopping (writing/compiling dll, loading dll to program, unloading, and repeating). Can someone give me some idea on how computers work? Is anything better possible? Like a running program, that can accept user input and compile it and then unload it later? I mean heck operating systems dont need to be RESTARTED with every change to user input. What is this the cave man days? Sorry, it's just so super frustrating not knowing what one can do, and can't do. If only I could understand and learn this stuff fast enough.

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• How can I make this script output each categories item per category [closed]

  - by Duice352

  Ok so here is the deal currently this script outputs all the products in a parent category as well as the products in the child categories. What i would like to do is seperate the output based on child categories. All the child categories are in the array $children and the string $childs. The parent category is the first array element of $children with the following ones being the actual children. The category names are stored in the database $result as " $cat_name ". I want to first Display the cat_name then the products that fall in that category and then display the next child cat_name and items, ect. Any suggestions of how to manipulate the while loop that cylcles through the rows? <?php $productsPerRow = 3; $productsPerPage = 15; //$productList = getProductList($catId); $children = array_merge(array($catId), getChildCategories(NULL, $catId)); $childs = ' (' . implode(', ', $children) . ')'; $sql = "SELECT pd_id, pd_name, pd_price, pd_thumbnail, pd_qty, c.cat_id, c.cat_name FROM tbl_product pd, tbl_category c WHERE pd.cat_id = c.cat_id AND pd.cat_id IN $childs ORDER BY pd_name"; $result = dbQuery(getPagingQuery($sql, $productsPerPage)); $pagingLink = getPagingLink($sql, $productsPerPage, "c=$catId"); $numProduct = dbNumRows($result); // the product images are arranged in a table. to make sure // each image gets equal space set the cell width here $columnWidth = (int)(100 / $productsPerRow); ?> <p><?php if(isset($_GET['m'])){echo "You must select a model first! After you select your model you can customize your dragster parts.";} ?> </p> <p align="center"><?php echo $pagingLink; ?></p> <table width="100%" border="0" cellspacing="0" cellpadding="20"> <?php if ($numProduct > 0 ) { $i = 0; while ($row = dbFetchAssoc($result)) { extract($row); if ($pd_thumbnail) { $pd_thumbnail = WEB_ROOT . 'images/product/' .$pd_thumbnail; } else { $pd_thumbnail = 'images/no-image-small.png'; } if ($i % $productsPerRow == 0) { echo '<tr>'; } // format how we display the price $pd_price = displayAmount($pd_price); echo "<td width=\"$columnWidth%\" align=\"center\"><a href=\"" . $_SERVER['PHP_SELF'] . "?c=$catId&p=$pd_id" . "\"><img src=\"$pd_thumbnail\" border=\"0\"><br>$pd_name</a><br>Price : $pd_price <br> $cat_id - $cat_name"; // if the product is no longer in stock, tell the customer if ($pd_qty <= 0) { echo "<br>Out Of Stock"; } echo "</td>\r\n"; if ($i % $productsPerRow == $productsPerRow - 1) { echo '</tr>'; } $i += 1; } if ($i % $productsPerRow > 0) { echo '<td colspan="' . ($productsPerRow - ($i % $productsPerRow)) . '">&nbsp;</td>'; }

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• Using Diskpart in a PowerShell script won't allow script to reuse drive letter

  - by Kyle

  I built a script that mounts (attach) a VHD using Diskpart, cleans out some system files and then unmounts (detach) it. It uses a foreach loop and is suppose to clean multiple VHD using the same drive letter. However, after the 1st VHD it fails. I also noticed that when I try to manually attach a VHD with diskpart, diskpart succeeds, the Disk Manager shows the disk with the correct drive letter, but within the same PoSH instance I can not connect (set-location) to that drive. If I do a manual diskpart when I 1st open PoSH I can attach and detach all I want and I get the drive letter every time. Is there something I need to do to reset diskpart in the script? Here's a snippet of the script I'm using. function Mount-VHD { [CmdletBinding()] param ( [Parameter(Position=0,Mandatory=$true,ValueFromPipeline=$false)] [string]$Path, [Parameter(Position=1,Mandatory=$false,ValueFromPipeline=$false)] [string]$DL, [string]$DiskpartScript = "$env:SystemDrive\DiskpartScript.txt", [switch]$Rescan ) begin { function InvokeDiskpart { Diskpart.exe /s $DiskpartScript } ## Validate Operating System Version ## if (Get-WmiObject win32_OperatingSystem -Filter "Version < '6.1'") {throw "The script operation requires at least Windows 7 or Windows Server 2008 R2."} } process{ ## Diskpart Script Content ## Here-String statement purposefully not indented ## @" $(if ($Rescan) {'Rescan'}) Select VDisk File="$Path" `nAttach VDisk Exit "@ | Out-File -FilePath $DiskpartScript -Encoding ASCII -Force InvokeDiskpart Start-Sleep -Seconds 3 @" Select VDisk File="$Path"`nSelect partition 1 `nAssign Letter="$DL" Exit "@ | Out-File -FilePath $DiskpartScript -Encoding ASCII -Force InvokeDiskpart } end { Remove-Item -Path $DiskpartScript -Force ; "" Write-Host "The VHD ""$Path"" has been successfully mounted." ; "" } } function Dismount-VHD { [CmdletBinding()] param ( [Parameter(Position=0,Mandatory=$true,ValueFromPipeline=$false)] [string]$Path, [switch]$Remove, [switch]$NoConfirm, [string]$DiskpartScript = "$env:SystemDrive\DiskpartScript.txt", [switch]$Rescan ) begin { function InvokeDiskpart { Diskpart.exe /s $DiskpartScript } function RemoveVHD { switch ($NoConfirm) { $false { ## Prompt for confirmation to delete the VHD file ## "" ; Write-Warning "Are you sure you want to delete the file ""$Path""?" $Prompt = Read-Host "Type ""YES"" to continue or anything else to break" if ($Prompt -ceq 'YES') { Remove-Item -Path $Path -Force "" ; Write-Host "VHD ""$Path"" deleted!" ; "" } else { "" ; Write-Host "Script terminated without deleting the VHD file." ; "" } } $true { ## Confirmation prompt suppressed ## Remove-Item -Path $Path -Force "" ; Write-Host "VHD ""$Path"" deleted!" ; "" } } } ## Validate Operating System Version ## if (Get-WmiObject win32_OperatingSystem -Filter "Version < '6.1'") {throw "The script operation requires at least Windows 7 or Windows Server 2008 R2."} } process{ ## DiskPart Script Content ## Here-String statement purposefully not indented ## @" $(if ($Rescan) {'Rescan'}) Select VDisk File="$Path"`nDetach VDisk Exit "@ | Out-File -FilePath $DiskpartScript -Encoding ASCII -Force InvokeDiskpart Start-Sleep -Seconds 10 } end { if ($Remove) {RemoveVHD} Remove-Item -Path $DiskpartScript -Force ; "" } }

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• Ububtu server 12.04 auto installation freezes at kickseeding running if ks.cfg has post scripts

  - by john206

  I'm trying to make a custom Ubuntu Server iso file. Kickstart file (ks.cfg) runs smooth when there is no %post in the file and Ubuntu installs correctly with ks configuration. Installation finishes installing base, apt, grub and It echos: Kickseed Running... and it freezes @ 0% I thought may be apt-get update doesnt work in ks file, I tried to install other apps like apache2 but no luck I have created dozen iso images and installed them in Virtual Box.I have been googling for 3 days and checked out ubuntu forums but haven't figured out the issue. I appreciate your help. This is how I made the iso image. My ks.file and txt.cfg files located in isolinux directory: root@ubuntu:/home/work mount -o loop ubuntu-12.04-amd64.iso original-iso/ rsync -a original-iso/ custom-iso/ cp ks.cfg custom-iso/isolinux/ cp txt.cfg custom-iso/isolinux/ chmod -R 777 custom-iso/ #Creating Iso image mkisofs -D -r -V “$IMAGE_NAME” -cache-inodes -J -l -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -o ~/ubuntu-12.04-alternate-custom-amd64.iso custom-iso/ ks.cfg #Generated by Kickstart Configurator #platform=AMD64 or Intel EM64T #System language lang en_US #Language modules to install langsupport en_US #System keyboard keyboard us #System mouse mouse #System timezone timezone America/Los_Angeles #Root password rootpw --iscrypted somethingsomething #Initial user user ubuntu --fullname "ubuntu" --iscrypted --password somethingsomething. #Reboot after installation reboot #Use text mode install text #Install OS instead of upgrade install #Use CDROM installation media cdrom #System bootloader configuration bootloader --location=mbr #Clear the Master Boot Record zerombr yes #Partition clearing information clearpart --all --initlabel #Disk partitioning information part /boot --size 128 --fstype=ext3 --asprimary part / --size 512 --fstype=ext3 --asprimary part swap --size 512 part /tmp --size 512 --fstype=ext3 part /var --size 512 --fstype=ext3 part /usr --size 4096 --fstype=ext3 part /home --size 2048 --fstype=ext3 #System authorization infomation auth --useshadow --enablemd5 #Network information network --bootproto=dhcp --device=eth0 #Firewall configuration firewall --disabled --http --ftp --ssh #X Window System configuration information xconfig --depth=32 --resolution=1024x768 --defaultdesktop=GNOME %post apt-get update mkdir /home/user txt.cfg default autoinstall label autoinstall menu label ^Install Custom Ubuntu Server kernel /install/vmlinuz append file=/cdrom/preseed/ubuntu-server.seed initrd=/install/initrd.gz quiet ks=cdrom:/isolinux/ks.cfg -- label install menu label ^Install Ubuntu Server kernel /install/vmlinuz append file=/cdrom/preseed/ubuntu-server.seed vga=788 initrd=/install/initrd.gz quiet -- label cloud menu label ^Multiple server install with MAAS kernel /install/vmlinuz append modules=maas-enlist-udeb vga=788 initrd=/install/initrd.gz quiet -- label check menu label ^Check disc for defects kernel /install/vmlinuz append MENU=/bin/cdrom-checker-menu vga=788 initrd=/install/initrd.gz quiet -- label memtest menu label Test ^memory kernel /install/mt86plus label hd menu label ^Boot from first hard disk localboot 0x80

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• Secure ldap problem

  - by neverland

  I have tried to config my openldap to have secure connection by using openssl on Debian5. By the way, I got trouble during the below command. ldap:/etc/ldap# slapd -h 'ldap:// ldaps://' -d1 >>> slap_listener(ldaps://) connection_get(15): got connid=7 connection_read(15): checking for input on id=7 connection_get(15): got connid=7 connection_read(15): checking for input on id=7 connection_get(15): got connid=7 connection_read(15): checking for input on id=7 connection_get(15): got connid=7 connection_read(15): checking for input on id=7 connection_read(15): unable to get TLS client DN, error=49 id=7 connection_get(15): got connid=7 connection_read(15): checking for input on id=7 ber_get_next ber_get_next on fd 15 failed errno=0 (Success) connection_closing: readying conn=7 sd=15 for close connection_close: conn=7 sd=15 Then I have search for "unable to get TLS client DN, error=49 id=7" but it seems no where has a good solution to this yet. Please help. Thanks # Well, I try to fix something to get it work but now I got this ldap:~# slapd -d 256 -f /etc/openldap/slapd.conf @(#) $OpenLDAP: slapd 2.4.11 (Nov 26 2009 09:17:06) $ root@SD6-Casa:/tmp/buildd/openldap-2.4.11/debian/build/servers/slapd could not stat config file "/etc/openldap/slapd.conf": No such file or directory (2) slapd stopped. connections_destroy: nothing to destroy. What should I do now? log : ldap:~# /etc/init.d/slapd start Starting OpenLDAP: slapd - failed. The operation failed but no output was produced. For hints on what went wrong please refer to the system's logfiles (e.g. /var/log/syslog) or try running the daemon in Debug mode like via "slapd -d 16383" (warning: this will create copious output). Below, you can find the command line options used by this script to run slapd. Do not forget to specify those options if you want to look to debugging output: slapd -h 'ldaps:///' -g openldap -u openldap -f /etc/ldap/slapd.conf ldap:~# tail /var/log/messages Feb 8 16:53:27 ldap kernel: [ 123.582757] intel8x0_measure_ac97_clock: measured 57614 usecs Feb 8 16:53:27 ldap kernel: [ 123.582801] intel8x0: measured clock 172041 rejected Feb 8 16:53:27 ldap kernel: [ 123.582825] intel8x0: clocking to 48000 Feb 8 16:53:27 ldap kernel: [ 131.469687] Adding 240932k swap on /dev/hda5. Priority:-1 extents:1 across:240932k Feb 8 16:53:27 ldap kernel: [ 133.432131] EXT3 FS on hda1, internal journal Feb 8 16:53:27 ldap kernel: [ 135.478218] loop: module loaded Feb 8 16:53:27 ldap kernel: [ 141.348104] eth0: link up, 100Mbps, full-duplex Feb 8 16:53:27 ldap rsyslogd: [origin software="rsyslogd" swVersion="3.18.6" x-pid="1705" x-info="http://www.rsyslog.com"] restart Feb 8 16:53:34 ldap kernel: [ 159.217171] NET: Registered protocol family 10 Feb 8 16:53:34 ldap kernel: [ 159.220083] lo: Disabled Privacy Extensions

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• Excel on Mac Mini OS X Version 10.7.2 - Create text file named after a cell containing other cell data from other cells

  - by user143041

  I tried using the code below for the Excel program on my `Mac Mini using the OS X Version 10.7.2 and it keeps saying Error due to file name / path: (The Excel fiel I am creating is going to be a template with my formulas and macros installed which will be used over and over). Sub CreateFile() Do While Not IsEmpty(ActiveCell.Offset(0, 1)) MyFile = ActiveCell.Value & ".txt" fnum = FreeFile() Open MyFile For Output As fnum Print #fnum, ActiveCell.Offset(0, 1) & " " & ActiveCell.Offset(0, 2) Close #fnum ActiveCell.Offset(1, 0).Select Loop End Sub What Im trying to do: 1st Objective I would like to have the following data to be used to create a text file. A:A is what I need the name of the file to be. B:2 is the content I need in the text file. So, A2 - "repair-video-game-Glassboro-NJ-08028.txt" is the file name and B2 to be the content in the file. Next, A3 is the file name and B3 is the content for the file, etc. ONCE the content reads what is in cell A16 and B16 (length will vary), the file creation should stop, if not then I can delete the additional files created. This sheet will never change. Is there a way to establish the excel macro to always go to this sheet instead of have to select it with the mouse to identify the starting point? 2nd Objective I would like to have the following data to be used to create a text file. A:1 is what I need the name of the file to be. B:B is the content I want in the file. So, A2 - is the file name "geo-sitemap.xml" and B:B to be the content in the file (ignore the .xml file extension in the photo). ONCE the content cell reads what is in cell "B16" (length will vary), the file creation should stop, if not then I can adjust the cells that have need content (formulated content you see in the image is preset for 500 rows). This sheet will never change. Is there a way to establish the excel macro to always go to this sheet instead of have to select it with the mouse to identify the starting point? I can Provide the content in the cells that are filled in by excel formulas that are not not to be included in the .txt files. It is ok if it is not possible. I can delete the extra cells that are not populated (based on the data sheet). Please let me know if you need any more additional information or clarity and I will be happy to provide it. I really appreciate your help! Thank you

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