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  • How do I limit the game loop?

    - by user1758938
    How do I make a game update at a consistent speed? For example, this would loop too fast: while(true) { GetInput(); Render(); } This just wont work (hard to explain): while(true) { GetInput(); Render(); Sleep(16); } How do I sync my game to a certain framerate and still have input and functions going at a consistent rate?

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  • How to define AUTHPARAMS in Amazon EC2 API call

    - by The Joker
    I am trying to make an API call to EC2. I want to add my IP address to the security group. https://ec2.amazonaws.com/ ?Action=AuthorizeSecurityGroupIngress &GroupName=grppp20 &GroupId=sg-b2z982mq &IpPermissions.1.IpProtocol=tcp &IpPermissions.1.FromPort=3389 &IpPermissions.1.ToPort=3389 &IpPermissions.1.IpRanges.1.CidrIp=22.951.17.728/32 &&AWSAccessKeyId=AOPLDRACULALK6U7A And i get the following error. AWS was not able to validate the provided access credentials I have a secret access key & a username. I searched internet & found that we have to make a signature of the secret key & use it in the request instead of adding it directly. Can anyone tell me how to make a signature of my AWS secret key & how to use them with my API call? Let my secret key be: 2WwRiQzBs7RTFG4545PIOJ7812CXZ Username: thejoker

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  • Document-oriented vs Column-oriented database fit

    - by user1007922
    I have a data-intensive application that desperately needs a database make-over. The general data model: There are records with RIDs, grouped together by group IDs (GID). The records have arbitrary data fields, (maybe 5-15) with a few of them mandatory and the rest optional, and thus sparse. The general use model: There are LOTS and LOTS of Writes. Millions to Billions of records are stored. Very often, they are associated with new GIDs, but sometimes, they are associated with existing GIDs. There aren't as many reads, but when they happen, they need to be pretty fast or at least constant speed regardless of the database size. And when the reads happen, it will need to retrieve all the records/RIDs with a certain GID. I don't have a need to search by the record field values. Primarily, I will need to query by the GID and maybe RID. What database implementation should I use? I did some initial research between document-oriented and column-oriented databases and it seems the document-oriented ones are a good fit, model-wise. I could store all the records together under the same document key using the GID. But I don't really have any use for their ability to search the document contents itself. I like the simplicity and scalability of column-oriented databases like Cassandra, but how should I model my data in this paradigm for optimal performance? Should my key be the GID and should I create a column for each record/RID? (there maybe thousands or hundreds of thousands of records in a group/GID). Or should my key be the RID and ensure each row has a column for the GID value? What results in faster writes and reads under this model?

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  • Multi threaded game - updating, rendering, and how to split them

    - by CodeBunny
    From the StackOverflow post (it was recommended I move this): So, I'm working on a game engine, and I've made pretty good progress. However, my engine is single-threaded, and the advantages of splitting updating and rendering into separate threads sounds like a very good idea. How should I do this? Single threaded game engines are (conceptually) very easy to make, you have a loop where you update - render - sleep - repeat. However, I can't think of a good way to break updating and rendering apart, especially if I change their update rates (say I go through the update loop 25x a second, and have 60fps for rendering) - what if I begin updating halfway through a render loop, or vice versa?

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  • What would a start-to-finish development procedure would look like?

    - by Tom Busby
    I have a problem that my developer friends share. We recently left university and find ourselves either end up working for a firm which already has good procedures (TDD, automated testing, proper agile development, etc) or working for a firm which doesn't. I want to learn some of these vital skills and get a grip on what a complete start-to-finish development procedure would look like. What differences would be between a smaller project, and a long term project with many team members.

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  • How do I build a 2D physics engine?

    - by Vish
    The most advanced games I've made are a 8-ball pool game made with the physics engine Box2dFlashAS3 and a platform game with levels. When I did platform games, I've always wished to know how to make an engine, so that I could re-use it. When I see games that have slopes, curved slopes, perfect gravity and real-life physics, I've always wished I knew how to code the engine. Please suggest techniques and articles for whatever relevant knowledge-base is necessary.

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  • Sharp Architecture 1.9.5 Released

    - by AlecWhittington
    The S#arp Architecture team is proud to announce the release of version 1.9.5. This version has had the following changes: Upgraded to MVC 3 RTM Solution upgraded to .NET 4 Implementation of IDependencyResolver provided, but not implemented This marks the last scheduled release of 1.X for S#arp Architecture . The team is working hard to get the 2.0 release out the door and we hope to have a preview of that coming soon. With regards to IDependencyResolver, we have provided an implementation, but have...(read more)

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  • Testing for Auto Save and Load Game

    - by David Dimalanta
    I'm trying to make a simple app that will test the save and load state. Is it a good idea to make an app that has an auto save and load game every time the newbies open the first app then continues it on the other day? I'm trying to make a simple app with a simple moving block sprite, starting at the center coordinate. Once I moved the sprite to the top by touch n' drag, I touch the back key to close the app. I expected that once I re-open the app and the block sprite is still at the top. But instead, it goes back to the center instead. Where can I find more ways to use the preferences or manipulating by telling the dispose method to dispose only specific wastes but not the important records (fastest time, last time where the sprite is located via coordinates, etc.). Is there really an easy way or it has no shortcuts but most effective way? I need help to expand more ideas. Thank you. Here are the following links that I'm trying to figure it out how to use them: http://www.youtube.com/watch?v=gER5GGQYzGc http://www.badlogicgames.com/wordpress/?p=1585 http://www.youtube.com/watch?v=t0PtLexfBCA&feature=relmfu Take note that these links above are codes. But I'm not looking answers for code but to look how to start or figure it out how to use them. Tell me if I'm wrong.

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  • Can I use a genetic algorithm for balancing character builds?

    - by Renan Malke Stigliani
    I'm starting to build a online PVP (duel like, one-on-one) game, where there is leveling, skill points, special attacks and all the common stuff. Since I have never done anything like this, I'm still thinking about the math behind the levels/skills/specials balance. So I thought a good way of testing the best builds/combos, would be to implement a Genetic Algorithm. It'd be like this: Generate a big group of random characters Make them fight, level them up accordingly to their victories(more XP)/losses(less XP) Mate the winners, crossing their builds, to try and make even better characters Add some more random chars, emulating new players Repeat the process for some time, or util I find some chars who can beat everyone's butt I could then play with the math and try to find better balances to make sure that the top x% of chars would be a mix of various build types. So, is it a good idea, or is there some other, easier method to do the balancing?

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  • In retrospect, has it been a good idea to use three-valued logic for SQL NULL comparisons?

    - by Heinzi
    In SQL, NULL means "unknown value". Thus, every comparison with NULL yields NULL (unknown) rather than TRUE or FALSE. From a conceptional point of view, this three-valued logic makes sense. From a practical point of view, every learner of SQL has, one time or another, made the classic WHERE myField = NULL mistake or learned the hard way that NOT IN does not do what one would expect when NULL values are present. It is my impression (please correct me if I am wrong) that the cases where this three-valued logic helps (e.g. WHERE myField IS NOT NULL AND myField <> 2 can be shortened to WHERE myField <> 2) are rare and, in those cases, people tend to use the longer version anyway for clarity, just like you would add a comment when using a clever, non-obvious hack. Is there some obvious advantage that I am missing? Or is there a general consensus among the development community that this has been a mistake?

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  • Are CQRS/DDD/Event Sourcing and REST compatible?

    - by Robin Green
    REST seems to promote the idea of a canonical URL for a resource, and PUTing/POSTing back a modified representation of that resource in order to change it. However, with CQRS - Command Query Responsibility Segregation - one can theoretically have a completely different "API" for reading and for writing, which seems to conflict with the REST ideal of one URL for a resource, and no RPC-style "verbs inside the request body". DDD and Event Sourcing sometimes go together with CQRS, which is why I mention them in this question. So, can CQRS be used together with REST? Or is it against the REST way of doing things? What about DDD? And Event Sourcing? Can they be used with REST?

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  • What happened to Alan Cooper's Unified File Model?

    - by PAUL Mansour
    For a long time Alan Cooper (in the 3 versions of his book "About Face") has been promoting a "unified file model" to, among other things, dispense with what he calls the most idiotic message box ever invented - the one the pops up when hit the close button on an app or form saying "Do you want to discard your changes?" I like the idea and his arguments, but also have the knee-jerk reaction against it that most seasoned programmers and users have. While Cooper's book seems quite popular and respected, there is remarkably little discussion of this particular issue on the Web that I can find. Petter Hesselberg, the author of "Programming Industrial Strength Windows" mentions it but that seems about it. I have an opportunity to implement this in the (desktop) project I am working on, but face resistance by customers and co-workers, who are of course familiar with the MS Word and Excel way of doing things. I'm in a position to override their objections, but am not sure if I should. My questions are: Are there any good discussions of this that I have failed to find? Is anyone doing this in their apps? Is it a good idea that it is unfortunately not practical to implement until, say, Microsoft does it?

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  • Multi-module web project with Spring and Maven

    - by Johan Sjöberg
    Assume we have a few projects, each containing some web resources (e.g., html pages). parent.pom +- web (war) +- web-plugin-1 (jar) +- web-plugin-2 (jar) ... Let's say web is the deployable war project which depends on the known, but selectable, set of plugins. What is a good way to setup this using Spring and maven? Let the plugins be war projects and use mavens poor support for importing other war projects Put all web-resource for all plugins in the web project Add all web-resources to the classpath of all jar web-plugin-* dependencie and let spring read files from respective classpath? Other? I've previously come from using #1, but the copy-paste semantics of war dependencies in maven is horrible.

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  • Converting 2D Physics to 3D.

    - by static void main
    I'm new to game physics and I am trying to adapt a simple 2D ball simulation for a 3D simulation with the Java3D library. I have this problem: Two things: 1) I noted down the values generated by the engine: X/Y are too high and minX/minY/maxY/maxX values are causing trouble. Sometimes the balls are drawing but not moving Sometimes they are going out of the panel Sometimes they're moving on little area Sometimes they just stick at one place... 2) I'm unable to select/define/set the default correct/suitable values considering the 3D graphics scaling/resolution while they are set with respect to 2D screen coordinates, that is my only problem. Please help. This is the code: public class Ball extends GameObject { private float x, y; // Ball's center (x, y) private float speedX, speedY; // Ball's speed per step in x and y private float radius; // Ball's radius // Collision detected by collision detection and response algorithm? boolean collisionDetected = false; // If collision detected, the next state of the ball. // Otherwise, meaningless. private float nextX, nextY; private float nextSpeedX, nextSpeedY; private static final float BOX_WIDTH = 640; private static final float BOX_HEIGHT = 480; /** * Constructor The velocity is specified in polar coordinates of speed and * moveAngle (for user friendliness), in Graphics coordinates with an * inverted y-axis. */ public Ball(String name1,float x, float y, float radius, float speed, float angleInDegree, Color color) { this.x = x; this.y = y; // Convert velocity from polar to rectangular x and y. this.speedX = speed * (float) Math.cos(Math.toRadians(angleInDegree)); this.speedY = speed * (float) Math.sin(Math.toRadians(angleInDegree)); this.radius = radius; } public void move() { if (collisionDetected) { // Collision detected, use the values computed. x = nextX; y = nextY; speedX = nextSpeedX; speedY = nextSpeedY; } else { // No collision, move one step and no change in speed. x += speedX; y += speedY; } collisionDetected = false; // Clear the flag for the next step } public void collideWith() { // Get the ball's bounds, offset by the radius of the ball float minX = 0.0f + radius; float minY = 0.0f + radius; float maxX = 0.0f + BOX_WIDTH - 1.0f - radius; float maxY = 0.0f + BOX_HEIGHT - 1.0f - radius; double gravAmount = 0.9811111f; double gravDir = (90 / 57.2960285258); // Try moving one full step nextX = x + speedX; nextY = y + speedY; System.out.println("In serializedBall in collision."); // If collision detected. Reflect on the x or/and y axis // and place the ball at the point of impact. if (speedX != 0) { if (nextX > maxX) { // Check maximum-X bound collisionDetected = true; nextSpeedX = -speedX; // Reflect nextSpeedY = speedY; // Same nextX = maxX; nextY = (maxX - x) * speedY / speedX + y; // speedX non-zero } else if (nextX < minX) { // Check minimum-X bound collisionDetected = true; nextSpeedX = -speedX; // Reflect nextSpeedY = speedY; // Same nextX = minX; nextY = (minX - x) * speedY / speedX + y; // speedX non-zero } } // In case the ball runs over both the borders. if (speedY != 0) { if (nextY > maxY) { // Check maximum-Y bound collisionDetected = true; nextSpeedX = speedX; // Same nextSpeedY = -speedY; // Reflect nextY = maxY; nextX = (maxY - y) * speedX / speedY + x; // speedY non-zero } else if (nextY < minY) { // Check minimum-Y bound collisionDetected = true; nextSpeedX = speedX; // Same nextSpeedY = -speedY; // Reflect nextY = minY; nextX = (minY - y) * speedX / speedY + x; // speedY non-zero } } speedX += Math.cos(gravDir) * gravAmount; speedY += Math.sin(gravDir) * gravAmount; } public float getSpeed() { return (float) Math.sqrt(speedX * speedX + speedY * speedY); } public float getMoveAngle() { return (float) Math.toDegrees(Math.atan2(speedY, speedX)); } public float getRadius() { return radius; } public float getX() { return x; } public float getY() { return y; } public void setX(float f) { x = f; } public void setY(float f) { y = f; } } Here's how I'm drawing the balls: public class 3DMovingBodies extends Applet implements Runnable { private static final int BOX_WIDTH = 800; private static final int BOX_HEIGHT = 600; private int currentNumBalls = 1; // number currently active private volatile boolean playing; private long mFrameDelay; private JFrame frame; private int currentFrameRate; private Ball[] ball = new Ball[currentNumBalls]; private Random rand; private Sphere[] sphere = new Sphere[currentNumBalls]; private Transform3D[] trans = new Transform3D[currentNumBalls]; private TransformGroup[] objTrans = new TransformGroup[currentNumBalls]; public 3DMovingBodies() { rand = new Random(); float angleInDegree = rand.nextInt(360); setLayout(new BorderLayout()); GraphicsConfiguration config = SimpleUniverse .getPreferredConfiguration(); Canvas3D c = new Canvas3D(config); add("Center", c); ball[0] = new Ball(0.5f, 0.0f, 0.5f, 0.4f, angleInDegree, Color.yellow); // ball[1] = new Ball(1.0f, 0.0f, 0.25f, 0.8f, angleInDegree, // Color.yellow); // ball[2] = new Ball(0.0f, 1.0f, 0.15f, 0.11f, angleInDegree, // Color.yellow); trans[0] = new Transform3D(); // trans[1] = new Transform3D(); // trans[2] = new Transform3D(); sphere[0] = new Sphere(0.5f); // sphere[1] = new Sphere(0.25f); // sphere[2] = new Sphere(0.15f); // Create a simple scene and attach it to the virtual universe BranchGroup scene = createSceneGraph(); SimpleUniverse u = new SimpleUniverse(c); u.getViewingPlatform().setNominalViewingTransform(); u.addBranchGraph(scene); startSimulation(); } public BranchGroup createSceneGraph() { // Create the root of the branch graph BranchGroup objRoot = new BranchGroup(); for (int i = 0; i < currentNumBalls; i++) { // Create a simple shape leaf node, add it to the scene graph. objTrans[i] = new TransformGroup(); objTrans[i].setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE); Transform3D pos1 = new Transform3D(); pos1.setTranslation(randomPos()); objTrans[i].setTransform(pos1); objTrans[i].addChild(sphere[i]); objRoot.addChild(objTrans[i]); } BoundingSphere bounds = new BoundingSphere(new Point3d(0.0, 0.0, 0.0), 100.0); Color3f light1Color = new Color3f(1.0f, 0.0f, 0.2f); Vector3f light1Direction = new Vector3f(4.0f, -7.0f, -12.0f); DirectionalLight light1 = new DirectionalLight(light1Color, light1Direction); light1.setInfluencingBounds(bounds); objRoot.addChild(light1); // Set up the ambient light Color3f ambientColor = new Color3f(1.0f, 1.0f, 1.0f); AmbientLight ambientLightNode = new AmbientLight(ambientColor); ambientLightNode.setInfluencingBounds(bounds); objRoot.addChild(ambientLightNode); return objRoot; } public void startSimulation() { playing = true; Thread t = new Thread(this); t.start(); } public void stop() { playing = false; } public void run() { long previousTime = System.currentTimeMillis(); long currentTime = previousTime; long elapsedTime; long totalElapsedTime = 0; int frameCount = 0; while (true) { currentTime = System.currentTimeMillis(); elapsedTime = (currentTime - previousTime); // elapsed time in // seconds totalElapsedTime += elapsedTime; if (totalElapsedTime > 1000) { currentFrameRate = frameCount; frameCount = 0; totalElapsedTime = 0; } for (int i = 0; i < currentNumBalls; i++) { ball[i].move(); ball[i].collideWith(); drawworld(); } try { Thread.sleep(88); } catch (Exception e) { e.printStackTrace(); } previousTime = currentTime; frameCount++; } } public void drawworld() { for (int i = 0; i < currentNumBalls; i++) { printTG(objTrans[i], "SteerTG"); trans[i].setTranslation(new Vector3f(ball[i].getX(), ball[i].getY(), 0.0f)); objTrans[i].setTransform(trans[i]); } } private Vector3f randomPos() /* * Return a random position vector. The numbers are hardwired to be within * the confines of the box. */ { Vector3f pos = new Vector3f(); pos.x = rand.nextFloat() * 5.0f - 2.5f; // -2.5 to 2.5 pos.y = rand.nextFloat() * 2.0f + 0.5f; // 0.5 to 2.5 pos.z = rand.nextFloat() * 5.0f - 2.5f; // -2.5 to 2.5 return pos; } // end of randomPos() public static void main(String[] args) { System.out.println("Program Started"); 3DMovingBodiesbb = new 3DMovingBodies(); bb.addKeyListener(bb); MainFrame mf = new MainFrame(bb, 600, 400); } }

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  • Real-Time Strategy Gameplay

    - by Ahmad Alkhawaja
    I am working on building a HTML5 RTS game, and my current state is that I am building the Campaign mode of the game, and want to define the gameplay (The Scoring, Unit Behaviors/Attributes). I am searching for links/articles/books about how to define the gameplay, for me this: The scoring Figuring out levels of control (in any RTS game, there is units, individuals and squads) Unit action/attributes/properties point timing (how long it will take to play?) Achievements ..etc I want to see how they usually define these areas in RTS games, I expect to see general document discussing this concept that I can use to build the gameplay. Any idea? Is my question clear or I need to provide more details?

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  • Perpendicularity of a normal and a velocity?

    - by Milo
    I'm trying to fake angular velocity on my vehicle when it hits a wall by getting the dot product of the normal of the edge the car is hitting and the vehicle's velocity: Vector2D normVel = new Vector2D(); normVel.equals(vehicle.getVelocity()); normVel.normalize(); float dot = normVel.dot(outNorm); dot = -dot; vehicle.setAngularVelocity(vehicle.getAngularVelocity() + (dot * vehicle.getVelocity().length() * 0.01f)); outNorm is the normal of the wall. The problem is it only works half the time. It seems no matter what, the car always goes clockwise. If the car should head clockwise: -------------------------------------- / / I want the angular velocity to be positive, otherwise if it needs to go CCW: -------------------------------------- \ \ Then the angular velocity should be negative... What should I change to achieve this? Thanks Hmmm... Im not sure why this is not working... for(int i = 0; i < buildings.size(); ++i) { e = buildings.get(i); ArrayList<Vector2D> colPts = vehicle.getRect().getCollsionPoints(e.getRect()); float dist = OBB2D.collisionResponse(vehicle.getRect(), e.getRect(), outNorm); for(int u = 0; u < colPts.size(); ++u) { Vector2D p = colPts.get(u).subtract(vehicle.getRect().getCenter()); vehicle.setTorque(vehicle.getTorque() + p.cross(outNorm)); }

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  • Separating physics and game logic from UI code

    - by futlib
    I'm working on a simple block-based puzzle game. The game play consists pretty much of moving blocks around in the game area, so it's a trivial physics simulation. My implementation, however, is in my opinion far from ideal and I'm wondering if you can give me any pointers on how to do it better. I've split the code up into two areas: Game logic and UI, as I did with a lot of puzzle games: The game logic is responsible for the general rules of the game (e.g. the formal rule system in chess) The UI displays the game area and pieces (e.g. chess board and pieces) and is responsible for animations (e.g. animated movement of chess pieces) The game logic represents the game state as a logical grid, where each unit is one cell's width/height on the grid. So for a grid of width 6, you can move a block of width 2 four times until it collides with the boundary. The UI takes this grid, and draws it by converting logical sizes into pixel sizes (that is, multiplies it by a constant). However, since the game has hardly any game logic, my game logic layer [1] doesn't have much to do except collision detection. Here's how it works: Player starts to drag a piece UI asks game logic for the legal movement area of that piece and lets the player drag it within that area Player lets go of a piece UI snaps the piece to the grid (so that it is at a valid logical position) UI tells game logic the new logical position (via mutator methods, which I'd rather avoid) I'm not quite happy with that: I'm writing unit tests for my game logic layer, but not the UI, and it turned out all the tricky code is in the UI: Stopping the piece from colliding with others or the boundary and snapping it to the grid. I don't like the fact that the UI tells the game logic about the new state, I would rather have it call a movePieceLeft() method or something like that, as in my other games, but I didn't get far with that approach, because the game logic knows nothing about the dragging and snapping that's possible in the UI. I think the best thing to do would be to get rid of my game logic layer and implement a physics layer instead. I've got a few questions regarding that: Is such a physics layer common, or is it more typical to have the game logic layer do this? Would the snapping to grid and piece dragging code belong to the UI or the physics layer? Would such a physics layer typically work with pixel sizes or with some kind of logical unit, like my game logic layer? I've seen event-based collision detection in a game's code base once, that is, the player would just drag the piece, the UI would render that obediently and notify the physics system, and the physics system would call a onCollision() method on the piece once a collision is detected. What is more common? This approach or asking for the legal movement area first? [1] layer is probably not the right word for what I mean, but subsystem sounds overblown and class is misguiding, because each layer can consist of several classes.

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  • Rendering another screen on top of main game screen in fullscreen mode

    - by wolf
    my game runs in fullscreen mode and uses active rendering. The graphics are drawn on the fullscreen window in each game loop: public void render() { Window w = screen.getFullScreenWindow(); Graphics2D g = screen.getGraphics(); renderer.render(g, level, w.getWidth(), w.getHeight()); g.dispose(); screen.update(); } This is the screen.update() method: public void update(){ Window w = device.getFullScreenWindow(); if(w != null){ BufferStrategy s = w.getBufferStrategy(); if(!s.contentsLost()){ s.show(); } } } I want to display another screen on my main game screen (menu, inventory etc). Lets say I have a JPanel inventory, which has a grid of inventory cells (manually drawn) and some Swing components like JPopupMenu. So i tried adding that to my window and repainting it in the game loop, which worked okay most of the time... but sometimes the panel wouldn't get displayed. Blindly moving things around in the inventory worked, but it just didn't display. When i alt-tabbed out and back again, it displayed properly. I also tried drawing the rest of the inventory on my full screen window and using a JPanel to display only the buttons and popupmenus. The inventory displayed properly, but the Swing components keep flickering. I'm guessing this is because I don't know how to combine active and passive rendering. public void render() { Graphics2D g = screen.getGraphics(); invManager.render(g); g.dispose(); screen.update(); invPanel.repaint(); } Should i use something else instead of a JPanel? I don't really need active rendering for these screens, but I don't understand why they sometimes just don't display. Or maybe I should just make my own custom components instead of using Swing? I also read somewhere that using multiple panels/frames in a game is bad practice so should I draw everything on one window/frame/panel? If I CAN use JPanels for this, should I add and remove them every time the inventory is toggled? Or just change their visibility?

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  • The Unspoken - The Why of GC Ergonomics

    - by jonthecollector
    Do you use GC ergonomics, -XX:+UseAdaptiveSizePolicy, with the UseParallelGC collector? The jist of GC ergonomics for that collector is that it tries to grow or shrink the heap to meet a specified goal. The goals that you can choose are maximum pause time and/or throughput. Don't get too excited there. I'm speaking about UseParallelGC (the throughput collector) so there are definite limits to what pause goals can be achieved. When you say out loud "I don't care about pause times, give me the best throughput I can get" and then say to yourself "Well, maybe 10 seconds really is too long", then think about a pause time goal. By default there is no pause time goal and the throughput goal is high (98% of the time doing application work and 2% of the time doing GC work). You can get more details on this in my very first blog. GC ergonomics The UseG1GC has its own version of GC ergonomics, but I'll be talking only about the UseParallelGC version. If you use this option and wanted to know what it (GC ergonomics) was thinking, try -XX:AdaptiveSizePolicyOutputInterval=1 This will print out information every i-th GC (above i is 1) about what the GC ergonomics to trying to do. For example, UseAdaptiveSizePolicy actions to meet *** throughput goal *** GC overhead (%) Young generation: 16.10 (attempted to grow) Tenured generation: 4.67 (attempted to grow) Tenuring threshold: (attempted to decrease to balance GC costs) = 1 GC ergonomics tries to meet (in order) Pause time goal Throughput goal Minimum footprint The first line says that it's trying to meet the throughput goal. UseAdaptiveSizePolicy actions to meet *** throughput goal *** This run has the default pause time goal (i.e., no pause time goal) so it is trying to reach a 98% throughput. The lines Young generation: 16.10 (attempted to grow) Tenured generation: 4.67 (attempted to grow) say that we're currently spending about 16% of the time doing young GC's and about 5% of the time doing full GC's. These percentages are a decaying, weighted average (earlier contributions to the average are given less weight). The source code is available as part of the OpenJDK so you can take a look at it if you want the exact definition. GC ergonomics is trying to increase the throughput by growing the heap (so says the "attempted to grow"). The last line Tenuring threshold: (attempted to decrease to balance GC costs) = 1 says that the ergonomics is trying to balance the GC times between young GC's and full GC's by decreasing the tenuring threshold. During a young collection the younger objects are copied to the survivor spaces while the older objects are copied to the tenured generation. Younger and older are defined by the tenuring threshold. If the tenuring threshold hold is 4, an object that has survived fewer than 4 young collections (and has remained in the young generation by being copied to the part of the young generation called a survivor space) it is younger and copied again to a survivor space. If it has survived 4 or more young collections, it is older and gets copied to the tenured generation. A lower tenuring threshold moves objects more eagerly to the tenured generation and, conversely a higher tenuring threshold keeps copying objects between survivor spaces longer. The tenuring threshold varies dynamically with the UseParallelGC collector. That is different than our other collectors which have a static tenuring threshold. GC ergonomics tries to balance the amount of work done by the young GC's and the full GC's by varying the tenuring threshold. Want more work done in the young GC's? Keep objects longer in the survivor spaces by increasing the tenuring threshold. This is an example of the output when GC ergonomics is trying to achieve a pause time goal UseAdaptiveSizePolicy actions to meet *** pause time goal *** GC overhead (%) Young generation: 20.74 (no change) Tenured generation: 31.70 (attempted to shrink) The pause goal was set at 50 millisecs and the last GC was 0.415: [Full GC (Ergonomics) [PSYoungGen: 2048K-0K(26624K)] [ParOldGen: 26095K-9711K(28992K)] 28143K-9711K(55616K), [Metaspace: 1719K-1719K(2473K/6528K)], 0.0758940 secs] [Times: user=0.28 sys=0.00, real=0.08 secs] The full collection took about 76 millisecs so GC ergonomics wants to shrink the tenured generation to reduce that pause time. The previous young GC was 0.346: [GC (Allocation Failure) [PSYoungGen: 26624K-2048K(26624K)] 40547K-22223K(56768K), 0.0136501 secs] [Times: user=0.06 sys=0.00, real=0.02 secs] so the pause time there was about 14 millisecs so no changes are needed. If trying to meet a pause time goal, the generations are typically shrunk. With a pause time goal in play, watch the GC overhead numbers and you will usually see the cost of setting a pause time goal (i.e., throughput goes down). If the pause goal is too low, you won't achieve your pause time goal and you will spend all your time doing GC. GC ergonomics is meant to be simple because it is meant to be used by anyone. It was not meant to be mysterious and so this output was added. If you don't like what GC ergonomics is doing, you can turn it off with -XX:-UseAdaptiveSizePolicy, but be pre-warned that you have to manage the size of the generations explicitly. If UseAdaptiveSizePolicy is turned off, the heap does not grow. The size of the heap (and the generations) at the start of execution is always the size of the heap. I don't like that and tried to fix it once (with some help from an OpenJDK contributor) but it unfortunately never made it out the door. I still have hope though. Just a side note. With the default throughput goal of 98% the heap often grows to it's maximum value and stays there. Definitely reduce the throughput goal if footprint is important. Start with -XX:GCTimeRatio=4 for a more modest throughput goal (%20 of the time spent in GC). A higher value means a smaller amount of time in GC (as the throughput goal).

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  • storing map template in database

    - by Timigen
    I am working on an application that displays choropleth maps. These maps are of all different types, some display state by county, country by state/province, or world by country. How should I handle storing the map information in the database? My Thoughts: I won't need to do queries to find POI inside a region, so I don't think there is a need to use spatial datatypes. I am considering storing a map as a geoJSON object (I am using JS mapping library that accepts geoJSON). The only issue is what if I want a map of the US northeast. Then I would have geoJSON for the US and a separate one for the US northeast, which would be redundant. Would it make sense to have a shape database where I had each state then when I needed a map of the US I could query for each state, and when I needed a map of the US Northeast I could again query for what I need? Note: I am not concerned with storing the data for each region, just the region itself. I will query for the data on the fly for the specific region.

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  • What's the term for re-implementing an old API in terms of a newer API

    - by dodgy_coder
    The reason for doing it is to solve the case when a newer API is no longer backwards compatible with an older API. To explain, just say that there is an old API v1.0. The maker of this API decides it is broken and works on a new API v1.1 that intentionally breaks compatibility with the old API v1.0. Now, any programs written against the old API cannot be recompiled as-is with the new API. Then lets say there is a large app written against the old API and the developer doesn't have access to the source code. A solution would be to re-implement a "custom" old API v1.0 in terms of the new API v1.1 calls. So the "custom" v1.0 API is actually keeping the same interface/methods as the v1.0 API but inside its implementation it is actually making calls to the new API v1.1 methods. So the large app can be then compiled and linked against the "custom" v1.0 API and the new v1.1 API without any major source code changes. Is there a term for this practice? There's a recent example of this happening in Jamie Zawinski's port of XScreenSaver to the iPhone - he re-implemented the OpenGL 1.3 API in terms of the OpenGL ES 1.1 API. In this case, OpenGL 1.3 represents the "old" API and OpenGL ES 1.1 represents the "new" API.

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  • Latest DSTv15 Timezone Patches Available for E-Business Suite

    - by Steven Chan
    If your E-Business Suite Release 11i or 12 environment is configured to support Daylight Saving Time (DST) or international time zones, it's important to keep your timezone definition files up-to-date. They were last changed in July 2010 and released as DSTv14. DSTv15 is now available and certified with Oracle E-Business Suite Release 11i and 12. Is Your Apps Environment Affected?When a country or region changes DST rules or their time zone definitions, your Oracle E-Business Suite environment will require patching if:Your Oracle E-Business Suite environment is located in the affected country or region ORYour Oracle E-Business Suite environment is located outside the affected country or region but you conduct business or have customers or suppliers in the affected country or region We last discussed the DSTv14 patches on this blog. The latest "DSTv15" timezone definition file is cumulative and includes all DST changes released in earlier time zone definition files. DSTv15 includes changes to the following timezones since the DSTv14 release:Africa/Cairo 2010 2010Egypt 2010 2010America/Bahia_Banderas 2010 2010Asia/Amman 2002Asia/Gaza 2010 2010Europe/Helsinki 1981 1982Pacific/Fiji 2011Pacific/Apia 2011Hongkong 1977 1977Asia/Hong_Kong 1977 1977Europe/Mariehamn 1981 1982

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  • Ways to ensure unique instances of a class?

    - by Peanut
    I'm looking for different ways to ensure that each instance of a given class is a uniquely identifiable instance. For example, I have a Name class with the field name. Once I have a Name object with name initialised to John Smith I don't want to be able to instantiate a different Name object also with the name as John Smith, or if instantiation does take place I want a reference to the orginal object to be passed back rather than a new object. I'm aware that one way of doing this is to have a static factory that holds a Map of all the current Name objects and the factory checks that an object with John Smith as the name doesn't already exist before passing back a reference to a Name object. Another way I could think of off the top of my head is having a static Map in the Name class and when the constructor is called throwing an exception if the value passed in for name is already in use in another object, however I'm aware throwing exceptions in a constructor is generally a bad idea. Are there other ways of achieving this?

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