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• How can I gather client's data on Google App Engine without using Datastore/Backend Instances too much?

  - by ruslan

  One of the projects I'm working on is online survey engine. It's my first big commercial project on Google App Engine. I need your advice on how to collect stats and efficiently record them in DataStore without bankrupting me. Initial requirements are: After user finishes survey client sends list of pairs [ID (int) + PercentHit (double)]. This list shows how close answers of this user match predefined answers of reference answerers (which identified by IDs). I call them "target IDs". Creator of the survey wants to see aggregated % for given IDs for last hour, particular timeframe or from the beginning of the survey. Some surveys may have thousands of target/reference answerers. So I created entity public class HitsStatsDO implements Serializable { @Id transient private Long id; transient private Long version = (long) 0; transient private Long startDate; @Parent transient private Key parent; // fake parent which contains target id @Transient int targetId; private double avgPercent; private long hitCount; } But writing HitsStatsDO for each target from each user would give a lot of data. For instance I had a survey with 3000 targets which was answered by ~4 million people within one week with 300K people taking survey in first day. Even if we assume they were answering it evenly for 24 hours it would give us ~1040 writes/second. Obviously it hits concurrent writes limit of Datastore. I decided I'll collect data for one hour and save that, that's why there are avgPercent and hitCount in HitsStatsDO. GAE instances are stateless so I had to use dynamic backend instance. There I have something like this: // Contains stats for one hour private class Shard { ReadWriteLock lock = new ReentrantReadWriteLock(); Map<Integer, HitsStatsDO> map = new HashMap<Integer, HitsStatsDO>(); // Key is target ID public void saveToDatastore(); public void updateStats(Long startDate, Map<Integer, Double> hits); } and map with shard for current hour and previous hour (which doesn't stay here for long) private HashMap<Long, Shard> shards = new HashMap<Long, Shard>(); // Key is HitsStatsDO.startDate So once per hour I dump Shard for previous hour to Datastore. Plus I have class LifetimeStats which keeps Map<Integer, HitsStatsDO> in memcached where map-key is target ID. Also in my backend shutdown hook method I dump stats for unfinished hour to Datastore. There is only one major issue here - I have only ONE backend instance :) It raises following questions on which I'd like to hear your opinion: Can I do this without using backend instance ? What if one instance is not enough ? How can I split data between multiple dynamic backend instances? It hard because I don't know how many I have because Google creates new one as load increases. I know I can launch exact number of resident backend instances. But how many ? 2, 5, 10 ? What if I have no load at all for a week. Constantly running 10 backend instances is too expensive. What do I do with data from clients while backend instance is dead/restarting?

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• JOGL2 test compiles, but doesn't execute - help?

  - by Chuchinyi

  I have a problem with JOGL2. My JOGL2Template.java compiles fine, but executing it results in the following error: D:\java\java\jogl>javac JOGL2Template.java <== compile ok D:\java\java\jogl>java JOGL2Template <== execute error Exception in thread "main" java.lang.ExceptionInInitializerError at javax.media.opengl.GLProfile.<clinit>(GLProfile.java:1176) at JOGL2Template.<init>(JOGL2Template.java:24) at JOGL2Template.main(JOGL2Template.java:57) Caused by: java.lang.SecurityException: no certificate for gluegen-rt.dll in D:\ java\lib\gluegen-rt-natives-windows-i586.jar at com.jogamp.common.util.JarUtil.validateCertificate(JarUtil.java:350) at com.jogamp.common.util.JarUtil.validateCertificates(JarUtil.java:324) at com.jogamp.common.util.cache.TempJarCache.validateCertificates(TempJa rCache.java:328) at com.jogamp.common.util.cache.TempJarCache.bootstrapNativeLib(TempJarC ache.java:283) at com.jogamp.common.os.Platform$3.run(Platform.java:308) at java.security.AccessController.doPrivileged(Native Method) at com.jogamp.common.os.Platform.loadGlueGenRTImpl(Platform.java:298) at com.jogamp.common.os.Platform.<clinit>(Platform.java:207) ... 3 more Here is the JOGL2Template.java source code: import java.awt.Dimension; import java.awt.Frame; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import javax.media.opengl.GLAutoDrawable; import javax.media.opengl.GLCapabilities; import javax.media.opengl.GLEventListener; import javax.media.opengl.GLProfile; import javax.media.opengl.awt.GLCanvas; import com.jogamp.opengl.util.FPSAnimator; import javax.swing.JFrame; /* * JOGL 2.0 Program Template For AWT applications */ public class JOGL2Template extends JFrame implements GLEventListener { private static final int CANVAS_WIDTH = 640; // Width of the drawable private static final int CANVAS_HEIGHT = 480; // Height of the drawable private static final int FPS = 60; // Animator's target frames per second // Constructor to create profile, caps, drawable, animator, and initialize Frame public JOGL2Template() { // Get the default OpenGL profile that best reflect your running platform. GLProfile glp = GLProfile.getDefault(); // Specifies a set of OpenGL capabilities, based on your profile. GLCapabilities caps = new GLCapabilities(glp); // Allocate a GLDrawable, based on your OpenGL capabilities. GLCanvas canvas = new GLCanvas(caps); canvas.setPreferredSize(new Dimension(CANVAS_WIDTH, CANVAS_HEIGHT)); canvas.addGLEventListener(this); // Create a animator that drives canvas' display() at 60 fps. final FPSAnimator animator = new FPSAnimator(canvas, FPS); addWindowListener(new WindowAdapter() { // For the close button @Override public void windowClosing(WindowEvent e) { // Use a dedicate thread to run the stop() to ensure that the // animator stops before program exits. new Thread() { @Override public void run() { animator.stop(); System.exit(0); } }.start(); } }); add(canvas); pack(); setTitle("OpenGL 2 Test"); setVisible(true); animator.start(); // Start the animator } public static void main(String[] args) { new JOGL2Template(); } @Override public void init(GLAutoDrawable drawable) { // Your OpenGL codes to perform one-time initialization tasks // such as setting up of lights and display lists. } @Override public void display(GLAutoDrawable drawable) { // Your OpenGL graphic rendering codes for each refresh. } @Override public void reshape(GLAutoDrawable drawable, int x, int y, int w, int h) { // Your OpenGL codes to set up the view port, projection mode and view volume. } @Override public void dispose(GLAutoDrawable drawable) { // Hardly used. } } Any ideas what might be the cause of these errors?

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• The Future of Air Travel: Intelligence and Automation

  - by BobEvans

  Remember those white-knuckle flights through stormy weather where unexpected plunges in altitude result in near-permanent relocations of major internal organs? Perhaps there’s a better way, according to a recent Wall Street Journal article: “Pilots of a Honeywell International Inc. test plane stayed on their initial flight path, relying on the company's latest onboard radar technology to steer through the worst of the weather. The specially outfitted Boeing 757 barely shuddered as it gingerly skirted some of the most ferocious storm cells over Fort Walton Beach and then climbed above the rest in zero visibility.” Or how about the multifaceted check-in process, which might not wreak havoc on liver location but nevertheless makes you wonder if you’ve been trapped in some sort of covert psychological-stress test? Another WSJ article, called “The Self-Service Airport,” says there’s reason for hope there as well: “Airlines are laying the groundwork for the next big step in the airport experience: a trip from the curb to the plane without interacting with a single airline employee. At the airport of the near future, ‘your first interaction could be with a flight attendant,’ said Ben Minicucci, chief operating officer of Alaska Airlines, a unit of Alaska Air Group Inc.” And in the topsy-turvy world of air travel, it’s not just the passengers who’ve been experiencing bumpy rides: the airlines themselves are grappling with a range of challenges—some beyond their control, some not—that make profitability increasingly elusive in spite of heavy demand for their services. A recent piece in The Economist illustrates one of the mega-challenges confronting the airline industry via a striking set of contrasting and very large numbers: while the airlines pay $7 billion per year to third-party computerized reservation services, the airlines themselves earn a collective profit of only $3 billion per year. In that context, the anecdotes above point unmistakably to the future that airlines must pursue if they hope to be able to manage some of the factors outside of their control (e.g., weather) as well as all of those within their control (operating expenses, end-to-end visibility, safety, load optimization, etc.): more intelligence, more automation, more interconnectedness, and more real-time awareness of every facet of their operations. Those moves will benefit both passengers and the air carriers, says the WSJ piece on The Self-Service Airport: “Airlines say the advanced technology will quicken the airport experience for seasoned travelers—shaving a minute or two from the checked-baggage process alone—while freeing airline employees to focus on fliers with questions. ‘It's more about throughput with the resources you have than getting rid of humans,’ said Andrew O'Connor, director of airport solutions at Geneva-based airline IT provider SITA.” Oracle’s attempting to help airlines gain control over these challenges by blending together a range of its technologies into a solution called the Oracle Airline Data Model, which suggests the following steps: • To retain and grow their customer base, airlines need to focus on the customer experience. • To personalize and differentiate the customer experience, airlines need to effectively manage their passenger data. • The Oracle Airline Data Model can help airlines jump-start their customer-experience initiatives by consolidating passenger data into a customer data hub that drives realtime business intelligence and strategic customer insight. • Oracle’s Airline Data Model brings together multiple types of data that can jumpstart your data-warehousing project with rich out-of-the-box functionality. • Oracle’s Intelligent Warehouse for Airlines brings together the powerful capabilities of Oracle Exadata and the Oracle Airline Data Model to give you real-time strategic insights into passenger demand, revenues, sales channels and your flight network. The airline industry aside, the bullet points above offer a broad strategic outline for just about any industry because the customer experience is becoming pre-eminent in each and there is simply no way to deliver world-class customer experiences unless a company can capture, manage, and analyze all of the relevant data in real-time. I’ll leave you with two thoughts from the WSJ article about the new in-flight radar system from Honeywell: first, studies show that a single episode of serious turbulence can wrack up $150,000 in additional costs for an airline—so, it certainly behooves the carriers to gain the intelligence to avoid turbulence as much as possible. And second, it’s back to that top-priority customer-experience thing and the value that ever-increasing levels of intelligence can deliver. As the article says: “In the cabin, reporters watched screens showing the most intense parts of the nearly 10-mile wide storm, which churned some 7,000 feet below, in vibrant red and other colors. The screens also were filled with tiny symbols depicting likely locations of lightning and hail, which can damage planes and wreak havoc on the nerves of white-knuckle flyers.”  (Bob Evans is senior vice-president, communications, for Oracle.)  

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• Where Twitter Stands Heading Into 2013

  - by Mike Stiles

  As Twitter continued throughout 2012 to be a stage on which global politics and culture played itself out, the company itself underwent some adjustments that give us a good indication of what users and brands can expect from the platform in 2013. The power of the network did anything but fade. Celebrities continued to use it to connect one-on-one. Even the Pope signed on this year. It continued to fuel revolutions. It played an exponentially large factor in this US Presidential election. And around the world, the freedom to speak was challenged as users were fired, sued, sometimes even jailed for their tweets. Expect more of the same in 2013, as Twitter has entrenched itself, for individuals, causes and brands, as the fastest, easiest, most efficient way to message the masses so some measure of impact can come from it. It’s changed everything, and it’s not finished. These fun facts reveal the position of strength with which Twitter enters 2013: It now generates a billion tweets every 2.5 days It has 500 million+ users The average Twitter user has tweeted 307 times 32% of everyone using the Internet uses Twitter It’s expected to bring in $540 million in ad revenue by 2014 11 new accounts are created every second High-level Executive Summary: people love it, people use it, and they’re going to keep loving and using it. Whether or not outside developers love it is a different matter. 2012 marked a shift from welcoming the third party support that played at least some role in Twitter being so warmly embraced, to discouraging anything that replicates what Twitter can do itself…or plans to do itself. It’s not the open playground it once was. Now Twitter must spend 2013 proving it can innovate in-house and keep us just as entranced. Likewise, Twitter is distancing itself from Facebook. Images from the #1 platform’s Instagram don’t work on Twitter anymore, and Twitter’s rolling out their own photo filter product. Where the two have lived in a “plenty of room for everybody” symbiosis up to now, 2013 could see the giants ramping up a full-on rivalry. Twitter is exhibiting a deliberate strategy. Updates have centered on more visually appealing search results, and making finding and sharing content easier. Deals have been cut with some media entities so their content stands out. CEO Dick Costolo has said tweets aren’t the attraction, they’re what leads you to content. Twitter aims to be a key distributor of media and info. Add the addition of former News Corp. President Peter Chernin to the board, and their hashtag landing page experience for events, and their media behemoth ambitions get pretty clear. There are challenges ahead and Costolo has also laid those out; entry into China, figuring out how to have Twitter deliver both comprehensive and relevant, targeted experiences, and the visualization of big data. What does this mean for corporations? They can expect a more media-rich evolution and growing emphases on imagery. They can expect more opportunities to create great media content and leverage Twitter for its distribution. And they can expect new ways to surface in searches. Are brands diving in? 56% of customer tweets to companies get completely and totally ignored. Ugh. A study Twitter recently conducted with Compete shows people who see tweets from retailers are more likely to buy a product. And, the more retailer tweets they see, the more likely they are to purchase on the retail site. As more of those tweets point to engaging media content from the brand, the results should get even better. Twitter appears ready for 2013. Enterprise brands have some work to do. @mikestilesPhoto Stuart Miles, freedigitalphotos.net

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• Consumer Oriented Search In Oracle Endeca Information Discovery – Part 1

  - by Bob Zurek

  Information Discovery, a core capability of Oracle Endeca Information Discovery, enables business users to rapidly search, discover and navigate through a wide variety of big data including structured, unstructured and semi-structured data. One of the key capabilities, among many, that differentiate our solution from others in the Information Discovery market is our deep support for search across this growing amount of varied big data. Our method and approach is very different than classic simple keyword search that is found in may information discovery solutions. In this first part of a series on the topic of search, I will walk you through many of the key capabilities that go beyond the simple search box that you might experience in products where search was clearly an afterthought or attempt to catch up to our core capabilities in this area. Lets explore. The core data management solution of Oracle Endeca Information Discovery is the Endeca Server, a hybrid search-analytical database that his highly scalable and column-oriented in nature. We will talk in more technical detail about the capabilities of the Endeca Server in future blog posts as this post is intended to give you a feel for the deep search capabilities that are an integral part of the Endeca Server. The Endeca Server provides best-of-breed search features aw well as a new class of features that are the first to be designed around the requirement to bridge structured, semi-structured and unstructured big data. Some of the key features of search include type a heads, automatic alphanumeric spell corrections, positional search, Booleans, wildcarding, natural language, and category search and query classification dialogs. This is just a subset of the advanced search capabilities found in Oracle Endeca Information Discovery. Search is an important feature that makes it possible for business users to explore on the diverse data sets the Endeca Server can hold at any one time. The search capabilities in the Endeca server differ from other Information Discovery products with simple “search boxes” in the following ways: The Endeca Server Supports Exploratory Search.  Enterprise data frequently requires the user to explore content through an ad hoc dialog, with guidance that helps them succeed. This has implications for how to design search features. Traditional search doesn’t assume a dialog, and so it uses relevance ranking to get its best guess to the top of the results list. It calculates many relevance factors for each query, like word frequency, distance, and meaning, and then reduces those many factors to a single score based on a proprietary “black box” formula. But how can a business users, searching, act on the information that the document is say only 38.1% relevant? In contrast, exploratory search gives users the opportunity to clarify what is relevant to them through refinements and summaries. This approach has received consumer endorsement through popular ecommerce sites where guided navigation across a broad range of products has helped consumers better discover choices that meet their, sometimes undetermined requirements. This same model exists in Oracle Endeca Information Discovery. In fact, the Endeca Server powers many of the most popular e-commerce sites in the world. The Endeca Server Supports Cascading Relevance. Traditional approaches of search reduce many relevance weights to a single score. This means that if a result with a good title match gets a similar score to one with an exact phrase match, they’ll appear next to each other in a list. But a user can’t deduce from their score why each got it’s ranking, even though that information could be valuable. Oracle Endeca Information Discovery takes a different approach. The Endeca Server stratifies results by a primary relevance strategy, and then breaks ties within a strata by ordering them with a secondary strategy, and so on. Application managers get the explicit means to compose these strategies based on their knowledge of their own domain. This approach gives both business users and managers a deterministic way to set and understand relevance. Now that you have an understanding of two of the core search capabilities in Oracle Endeca Information Discovery, our next blog post on this topic will discuss more advanced features including set search, second-order relevance as well as an understanding of faceted search mechanisms that include queries and filters.  

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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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• Mastering snow and Java development at jDays in Gothenburg

  - by JavaCecilia

  Last weekend, I took the train from Stockholm to Gothenburg to attend and present at the new Java developer conference jDays. It was professionally arranged in the Swedish exhibition hall close to the amusement park Liseberg and we got a great deal out of the top-level presenters and hallway discussions. Understanding and Improving Your Java Process Our main purpose was to spread information on JVM and our monitoring tools for Java processes, so I held a crash course in the most important terms and concepts if you want to affect the performance of your Java process. From the beginning - the JVM specification to interpretation of heap usage graphs. For correct analysis, you also need to understand something about process memory - you need space for the Java heap (-Xms for initial size and -Xmx for max heap size), but the process memory also contain the thread stacks (to a size of -Xss), JVM internal data structures used for keeping track of Java objects on the heap, method compilation/optimization, native libraries, etc. If you get long pause times, make sure to monitor your application, see the allocation rate and frequency of pause times.My colleague Klara Ward then held a presentation on the Java Mission Control product, the profiling and diagnostics tools suite for HotSpot, coming soon. The room was packed and very appreciated, Klara demonstrated four different scenarios, e.g. how to diagnose and fix latencies due to lock contention for logging.My German colleague, OpenJDK ambassador Dalibor Topic travelled to Sweden to do the second keynote on "Make the Future Java". He let us in on the coming features and roadmaps of Java, now delivering major versions on a two-year schedule (Java 7 2011, Java 8 2013, etc). Also letting us in on where to download early versions of 8, to report problems early on. Software Development in teams Being a scout leader, I'm drilled in different team building and workshop techniques, creating strong groups - of course, I had to attend Henrik Berglund's session on building successful teams. He spoke about the importance of clear goals, autonomy and agreed processes. Thomas Sundberg ended the conference by doing live remote pair programming with Alex in Rumania and a concrete tips for people wanting to try it out (for local collaboration, remember to wash and change clothes). Memory Master Keynote The conference keynote was delivered by the Swedish memory master Mattias Ribbing, showing off by remembering the order of a deck of cards he'd seen once. He made it interactive by forcing the audience to learn a memory mastering technique of remembering ten ordered things by heart, asking us to shout out the order backwards and we made it! I desperately need this - bought the book, will get back on the subject. Continuous Delivery The most impressive presenter was Axel Fontaine on Continuous Delivery. Very well prepared slides with key images of his message and moved about the stage like a rock star. The topic is of course highly interesting, how to create an infrastructure enabling immediate feedback to developers and ability to release your product several times per day. Tomek Kaczanowski delivered a funny and useful presentation on good and bad tests, providing comic relief with poorly written tests and the useful rules of thumb how to rewrite them. To conclude, we had a great time and hope to see you at jDays next year :)

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• Numerically stable(ish) method of getting Y-intercept of mouse position?

  - by Fraser

  I'm trying to unproject the mouse position to get the position on the X-Z plane of a ray cast from the mouse. The camera is fully controllable by the user. Right now, the algorithm I'm using is... Unproject the mouse into the camera to get the ray: Vector3 p1 = Vector3.Unproject(new Vector3(x, y, 0), 0, 0, width, height, nearPlane, farPlane, viewProj; Vector3 p2 = Vector3.Unproject(new Vector3(x, y, 1), 0, 0, width, height, nearPlane, farPlane, viewProj); Vector3 dir = p2 - p1; dir.Normalize(); Ray ray = Ray(p1, dir); Then get the Y-intercept by using algebra: float t = -ray.Position.Y / ray.Direction.Y; Vector3 p = ray.Position + t * ray.Direction; The problem is that the projected position is "jumpy". As I make small adjustments to the mouse position, the projected point moves in strange ways. For example, if I move the mouse one pixel up, it will sometimes move the projected position down, but when I move it a second pixel, the project position will jump back to the mouse's location. The projected location is always close to where it should be, but it does not smoothly follow a moving mouse. The problem intensifies as I zoom the camera out. I believe the problem is caused by numeric instability. I can make minor improvements to this by doing some computations at double precision, and possibly abusing the fact that floating point calculations are done at 80-bit precision on x86, however before I start micro-optimizing this and getting deep into how the CLR handles floating point, I was wondering if there's an algorithmic change I can do to improve this? EDIT: A little snooping around in .NET Reflector on SlimDX.dll: public static Vector3 Unproject(Vector3 vector, float x, float y, float width, float height, float minZ, float maxZ, Matrix worldViewProjection) { Vector3 coordinate = new Vector3(); Matrix result = new Matrix(); Matrix.Invert(ref worldViewProjection, out result); coordinate.X = (float) ((((vector.X - x) / ((double) width)) * 2.0) - 1.0); coordinate.Y = (float) -((((vector.Y - y) / ((double) height)) * 2.0) - 1.0); coordinate.Z = (vector.Z - minZ) / (maxZ - minZ); TransformCoordinate(ref coordinate, ref result, out coordinate); return coordinate; } // ... public static void TransformCoordinate(ref Vector3 coordinate, ref Matrix transformation, out Vector3 result) { Vector3 vector; Vector4 vector2 = new Vector4 { X = (((coordinate.Y * transformation.M21) + (coordinate.X * transformation.M11)) + (coordinate.Z * transformation.M31)) + transformation.M41, Y = (((coordinate.Y * transformation.M22) + (coordinate.X * transformation.M12)) + (coordinate.Z * transformation.M32)) + transformation.M42, Z = (((coordinate.Y * transformation.M23) + (coordinate.X * transformation.M13)) + (coordinate.Z * transformation.M33)) + transformation.M43 }; float num = (float) (1.0 / ((((transformation.M24 * coordinate.Y) + (transformation.M14 * coordinate.X)) + (coordinate.Z * transformation.M34)) + transformation.M44)); vector2.W = num; vector.X = vector2.X * num; vector.Y = vector2.Y * num; vector.Z = vector2.Z * num; result = vector; } ...which seems to be a pretty standard method of unprojecting a point from a projection matrix, however this serves to introduce another point of possible instability. Still, I'd like to stick with the SlimDX Unproject routine rather than writing my own unless it's really necessary.

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• Simple Merging Of PDF Documents with iTextSharp 5.4.5.0

  - by Mladen Prajdic

  As we were working on our first SQL Saturday in Slovenia, we came to a point when we had to print out the so-called SpeedPASS's for attendees. This SpeedPASS file is a PDF and contains thier raffle, lunch and admission tickets. The problem is we have to download one PDF per attendee and print that out. And printing more than 10 docs at once is a pain. So I decided to make a little console app that would merge multiple PDF files into a single file that would be much easier to print. I used an open source PDF manipulation library called iTextSharp version 5.4.5.0 This is a console program I used. It’s brilliantly named MergeSpeedPASS. It only has two methods and is really short. Don't let the name fool you It can be used to merge any PDF files. The first parameter is the name of the target PDF file that will be created. The second parameter is the directory containing PDF files to be merged into a single file. using iTextSharp.text; using iTextSharp.text.pdf; using System; using System.IO; namespace MergeSpeedPASS { class Program { static void Main(string[] args) { if (args.Length == 0 || args[0] == "-h" || args[0] == "/h") { Console.WriteLine("Welcome to MergeSpeedPASS. Created by Mladen Prajdic. Uses iTextSharp 5.4.5.0."); Console.WriteLine("Tool to create a single SpeedPASS PDF from all downloaded generated PDFs."); Console.WriteLine(""); Console.WriteLine("Example: MergeSpeedPASS.exe targetFileName sourceDir"); Console.WriteLine(" targetFileName = name of the new merged PDF file. Must include .pdf extension."); Console.WriteLine(" sourceDir = path to the dir containing downloaded attendee SpeedPASS PDFs"); Console.WriteLine(""); Console.WriteLine(@"Example: MergeSpeedPASS.exe MergedSpeedPASS.pdf d:\Downloads\SQLSaturdaySpeedPASSFiles"); } else if (args.Length == 2) CreateMergedPDF(args[0], args[1]); Console.WriteLine(""); Console.WriteLine("Press any key to exit..."); Console.Read(); } static void CreateMergedPDF(string targetPDF, string sourceDir) { using (FileStream stream = new FileStream(targetPDF, FileMode.Create)) { Document pdfDoc = new Document(PageSize.A4); PdfCopy pdf = new PdfCopy(pdfDoc, stream); pdfDoc.Open(); var files = Directory.GetFiles(sourceDir); Console.WriteLine("Merging files count: " + files.Length); int i = 1; foreach (string file in files) { Console.WriteLine(i + ". Adding: " + file); pdf.AddDocument(new PdfReader(file)); i++; } if (pdfDoc != null) pdfDoc.Close(); Console.WriteLine("SpeedPASS PDF merge complete."); } } } } Hope it helps you and have fun.

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• Drawing texture does not work anymore with a small amount of triangles

  - by Paul

  When i draw lines, the vertices are well connected. But when i draw the texture inside the triangles, it only works with i<4 in the for loop, otherwise with i<5 for example, there is a EXC_BAD_ACCESS message, at @synthesize textureImage = _textureImage. I don't understand why. (The generatePolygons method seems to work fine as i tried to draw lines with many vertices as in the second image below. And textureImage remains the same for i<4 or i<5 : it's a 512px square image). Here are the images : What i want to achieve is to put the red points and connect them to the y-axis (the green points) and color the area (the green triangles) : If i only draw lines, it works fine : Then with a texture color, it works for i<4 in the loop (the red points in my first image, plus the fifth one to connect the last y) : But then, if i set i<5, the debug tool says EXC_BAD_ACCESS at the synthesize of _textureImage. Here is my code : I set a texture color in HelloWordLayer.mm with : CCSprite *textureImage = [self spriteWithColor:color3 textureSize:512]; _terrain.textureImage = textureImage; Then in the class Terrain, i create the vertices and put the texture in the draw method : @implementation Terrain @synthesize textureImage = _textureImage; //EXC_BAD_ACCESS for i<5 - (void)generatePath2{ CGSize winSize = [CCDirector sharedDirector].winSize; float x = 40; float y = 0; for(int i = 0; i < kMaxKeyPoints+1; ++i) { _hillKeyPoints[i] = CGPointMake(x, y); x = 150 + (random() % (int) 30); y += 30; } } -(void)generatePolygons{ _nPolyVertices = 0; float x1 = 0; float y1 = 0; int keyPoints = 0; for (int i=0; i<4; i++){ /* HERE : 4 = OK / 5 = crash */ //V0: at (0,0) _polyVertices[_nPolyVertices] = CGPointMake(x1, y1); _polyTexCoords[_nPolyVertices++] = CGPointMake(x1, y1); //V1: to the first "point" _polyVertices[_nPolyVertices] = CGPointMake(_hillKeyPoints[keyPoints].x, _hillKeyPoints[keyPoints].y); _polyTexCoords[_nPolyVertices++] = CGPointMake(_hillKeyPoints[keyPoints].x, _hillKeyPoints[keyPoints].y); keyPoints++; //from point at index 0 to 1 //V2, same y as point n°2: _polyVertices[_nPolyVertices] = CGPointMake(0, _hillKeyPoints[keyPoints].y); _polyTexCoords[_nPolyVertices++] = CGPointMake(0, _hillKeyPoints[keyPoints].y); //V1 again _polyVertices[_nPolyVertices] = _polyVertices[_nPolyVertices-2]; _polyTexCoords[_nPolyVertices++] = _polyVertices[_nPolyVertices-2]; //V2 again _polyVertices[_nPolyVertices] = _polyVertices[_nPolyVertices-2]; _polyTexCoords[_nPolyVertices++] = _polyVertices[_nPolyVertices-2]; //V3 = same x,y as point at index 1 _polyVertices[_nPolyVertices] = CGPointMake(_hillKeyPoints[keyPoints].x, _hillKeyPoints[keyPoints].y); _polyTexCoords[_nPolyVertices] = CGPointMake(_hillKeyPoints[keyPoints].x, _hillKeyPoints[keyPoints].y); y1 = _polyVertices[_nPolyVertices].y; _nPolyVertices++; } } - (id)init { if ((self = [super init])) { [self generatePath2]; [self generatePolygons]; } return self; } - (void) draw { //glDisable(GL_TEXTURE_2D); glDisableClientState(GL_COLOR_ARRAY); glDisableClientState(GL_TEXTURE_COORD_ARRAY); glBindTexture(GL_TEXTURE_2D, _textureImage.texture.name); glColor4f(1, 1, 1, 1); glVertexPointer(2, GL_FLOAT, 0, _polyVertices); glTexCoordPointer(2, GL_FLOAT, 0, _polyTexCoords); glDrawArrays(GL_TRIANGLE_STRIP, 0, (GLsizei)_nPolyVertices); glColor4f(1, 1, 1, 1); for(int i = 1; i < 40; ++i) { ccDrawLine(_polyVertices[i-1], _polyVertices[i]); } // restore default GL states glEnable(GL_TEXTURE_2D); glEnableClientState(GL_COLOR_ARRAY); glEnableClientState(GL_TEXTURE_COORD_ARRAY); } Do you see anything wrong in this code? Thanks for your help

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• X server with nvidia driver crashing: 12.04

  - by Raster

  My X server consistently crashes. It seems like this is happening when the X server is idle. This behaviour is new with 12.04. This is only happening on the second display of a multiseat system. Is there a configuration change I can make to stop this? X.Org X Server 1.11.3 Release Date: 2011-12-16 X Protocol Version 11, Revision 0 Build Operating System: Linux 2.6.42-26-generic x86_64 Ubuntu Current Operating System: Linux Desktop 3.2.0-29-generic #46-Ubuntu SMP Fri Jul 27 17:03:23 UTC 2012 x86_64 Kernel command line: BOOT_IMAGE=/vmlinuz-3.2.0-29-generic root=/dev/mapper/Group1-Root ro ramdisk_size=512000 quiet splash vt.handoff=7 Build Date: 04 August 2012 01:51:23AM xorg-server 2:1.11.4-0ubuntu10.7 (For technical support please see http://www.ubuntu.com/support) Current version of pixman: 0.24.4 Before reporting problems, check http://wiki.x.org to make sure that you have the latest version. Markers: (--) probed, (**) from config file, (==) default setting, (++) from command line, (!!) notice, (II) informational, (WW) warning, (EE) error, (NI) not implemented, (??) unknown. (==) Log file: "/var/log/Xorg.1.log", Time: Sun Sep 2 22:37:06 2012 (==) Using config file: "/etc/X11/xorg.conf" (==) Using system config directory "/usr/share/X11/xorg.conf.d" Backtrace: 0: /usr/bin/X (xorg_backtrace+0x26) [0x7fcee86be846] 1: /usr/bin/X (0x7fcee8536000+0x18c6ea) [0x7fcee86c26ea] 2: /lib/x86_64-linux-gnu/libpthread.so.0 (0x7fcee785c000+0xfcb0) [0x7fcee786bcb0] 3: /usr/lib/x86_64-linux-gnu/xorg/extra-modules/nvidia_drv.so (0x7fcee14ba000+0x902a9) [0x7fcee154a2a9] 4: /usr/lib/x86_64-linux-gnu/xorg/extra-modules/nvidia_drv.so (0x7fcee14ba000+0xfd5e7) [0x7fcee15b75e7] 5: /usr/lib/x86_64-linux-gnu/xorg/extra-modules/nvidia_drv.so (0x7fcee14ba000+0x4d6b92) [0x7fcee1990b92] 6: /usr/lib/x86_64-linux-gnu/xorg/extra-modules/nvidia_drv.so (0x7fcee14ba000+0x4d74d5) [0x7fcee19914d5] 7: /usr/lib/x86_64-linux-gnu/xorg/extra-modules/nvidia_drv.so (0x7fcee14ba000+0x4d767d) [0x7fcee199167d] 8: /usr/bin/X (0x7fcee8536000+0x1196ec) [0x7fcee864f6ec] 9: /usr/bin/X (0x7fcee8536000+0xe8ad5) [0x7fcee861ead5] 10: /usr/bin/X (0x7fcee8536000+0xe9d45) [0x7fcee861fd45] /etc/X11/xorg.conf Section "ServerLayout" Identifier "Desktop" Screen 0 "DesktopScreen" 0 0 InputDevice "DesktopMouse" "CorePointer" InputDevice "DesktopKeyboard" "CoreKeyboard" Option "AutoAddDevices" "false" Option "AllowEmptyInput" "true" Option "AutoEnableDevices" "false" EndSection Section "ServerLayout" Identifier "Desktop2" Screen 1 "Desktop2Screen" 0 0 InputDevice "Desktop2Mouse" "CorePointer" InputDevice "Desktop2Keyboard" "CoreKeyboard" Option "AutoAddDevices" "false" Option "AllowEmptyInput" "true" Option "AutoEnableDevices" "false" EndSection Section "Module" Load "dbe" Load "extmod" Load "type1" Load "freetype" Load "glx" EndSection Section "Files" EndSection Section "ServerFlags" Option "AutoAddDevices" "false" Option "AutoEnableDevices" "false" Option "AllowMouseOpenFail" "on" Option "AllowEmptyInput" "on" Option "ZapWarning" "on" Option "HandleSepcialKeys" "off" # Zapping on Option "DRI2" "on" Option "Xinerama" "0" EndSection # Desktop Mouse Section "InputDevice" Identifier "DesktopMouse" Driver "evdev" Option "Device" "/dev/input/event3" Option "Protocol" "auto" Option "GrabDevice" "on" Option "Emulate3Buttons" "no" Option "Buttons" "5" Option "ZAxisMapping" "4 5" Option "SendCoreEvents" "true" EndSection # Desktop2 Mouse Section "InputDevice" Identifier "Desktop2Mouse" Driver "evdev" Option "Device" "/dev/input/event5" Option "Protocol" "auto" Option "GrabDevice" "on" Option "Emulate3Buttons" "no" Option "Buttons" "5" Option "ZAxisMapping" "4 5" Option "SendCoreEvents" "true" EndSection Section "InputDevice" Identifier "DesktopKeyboard" Driver "evdev" Option "Device" "/dev/input/event4" Option "XkbRules" "xorg" Option "XkbModel" "105" Option "XkbLayout" "us" Option "Protocol" "Standard" Option "GrabDevice" "on" EndSection Section "InputDevice" Identifier "Desktop2Keyboard" Driver "evdev" Option "Device" "/dev/input/event6" Option "XkbRules" "xorg" Option "XkbModel" "105" Option "XkbLayout" "us" Option "Protocol" "Standard" Option "GrabDevice" "on" EndSection Section "Monitor" Identifier "Desktop2Monitor" VendorName "Acer" ModelName "Acer G235H" HorizSync 30.0 - 83.0 VertRefresh 56.0 - 75.0 Option "DPMS" EndSection Section "Monitor" Identifier "DesktopMonitor" VendorName "Acer" ModelName "Acer H213H" HorizSync 30.0 - 83.0 VertRefresh 56.0 - 75.0 Option "DPMS" EndSection Section "Device" Identifier "EVGACard" Driver "nvidia" VendorName "NVIDIA Corporation" BoardName "GeForce GTX 560 Ti" Option "Coolbits" "1" BusID "PCI:2:0:0" Screen 0 EndSection Section "Device" Identifier "XFXCard" Driver "nvidia" VendorName "NVIDIA Corporation" BoardName "GeForce GTX 9800" Option "Coolbits" "1" BusID "PCI:5:0:0" Screen 0 EndSection Section "Screen" Identifier "DesktopScreen" Device "EVGACard" Monitor "DesktopMonitor" DefaultDepth 24 SubSection "Display" Depth 24 EndSubSection EndSection Section "Screen" Identifier "Desktop2Screen" Device "XFXCard" Monitor "Desktop2Monitor" DefaultDepth 24 SubSection "Display" Depth 24 EndSubSection EndSection

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• My 2D collision code does not work as expected. How do I fix it?

  - by farmdve

  I have a simple 2D game with a tile-based map. I am new to game development, I followed the LazyFoo tutorials on SDL. The tiles are in a bmp file, but each tile inside it corresponds to an internal number of the type of tile(color, or wall). The game is simple, but the code is a lot so I can only post snippets. // Player moved out of the map if((player.box.x < 0)) player.box.x += GetVelocity(player, 0); if((player.box.y < 0)) player.box.y += GetVelocity(player, 1); if((player.box.x > (LEVEL_WIDTH - DOT_WIDTH))) player.box.x -= GetVelocity(player, 0); if((player.box.y > (LEVEL_HEIGHT - DOT_HEIGHT))) player.box.y -= GetVelocity(player, 1); // Now that we are here, we check for collisions if(touches_wall(player.box)) { if(player.box.x < player.prev_x) { player.box.x += GetVelocity(player, 0); } if(player.box.x > player.prev_x) { player.box.x -= GetVelocity(player, 0); } if(player.box.y < player.prev_y) { player.box.y += GetVelocity(player, 1); } if(player.box.y > player.prev_y) { player.box.y -= GetVelocity(player, 1); } } player.prev_x = player.box.x; player.prev_y = player.box.y; Let me explain, player is a structure with the following contents typedef struct { Rectangle box; //Player position on a map(tile or whatever). int prev_x, prev_y; // Previous positions int key_press[3]; // Stores which key was pressed/released. Limited to three keys. E.g Left,right and perhaps jump if possible in 2D int velX, velY; // Velocity for X and Y coordinate. //Health int health; bool main_character; uint32_t jump_ticks; } Player; And Rectangle is just a typedef of SDL_Rect. GetVelocity is a function that according to the second argument, returns the velocity for the X or Y axis. This code I have basically works, however inside the if(touches_wall(player.box)) if statement, I have 4 more. These 4 if statements are responsible for detecting collision on all 4 sides(up,down,left,right). However, they also act as a block for any other movement. Example: I move down the object and collide with the wall, as I continue to move down and still collide with the wall, I wish to move left or right, which is indeed possible(not to mention in 3D games), but remember the 4 if statements? They are preventing me from moving anywhere. The original code on the LazyFoo Productions website has no problems, but it was written in C++, so I had to rewrite most of it to work, which is probably where the problem comes from. I also use a different method of moving, than the one in the examples. Of course, that was just an example. I wish to be able to move no matter at which wall I collide. Before this bit of code, I had another one that had more logic in there, but it was flawed.

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• Fetching Partition Information

  - by Mike Femenella

  For a recent SSIS package at work I needed to determine the distinct values in a partition, the number of rows in each partition and the file group name on which each partition resided in order to come up with a grouping mechanism. Of course sys.partitions comes to mind for some of that but there are a few other tables you need to link to in order to grab the information required. The table I’m working on contains 8.8 billion rows. Finding the distinct partition keys from this table was not a fast operation. My original solution was to create  a temporary table, grab the distinct values for the partitioned column, then update via sys.partitions for the rows and the $partition function for the partitionid and finally look back to the sys.filegroups table for the filegroup names. It wasn’t pretty, it could take up to 15 minutes to return the results. The primary issue is pulling distinct values from the table. Queries for distinct against 8.8 billion rows don’t go quickly. A few beers into a conversation with a friend and we ended up talking about work which led to a conversation about the task described above. The solution was already built in SQL Server, just needed to pull it together. The first table I needed was sys.partition_range_values. This contains one row for each range boundary value for a partition function. In my case I have a partition function which uses dayid values. For example July 4th would be represented as an int, 20130704. This table lists out all of the dayid values which were defined in the function. This eliminated the need to query my source table for distinct dayid values, everything I needed was already built in here for me. The only caveat was that in my SSIS package I needed to create a bucket for any dayid values that were out of bounds for my function. For example if my function handled 20130501 through 20130704 and I had day values of 20130401 or 20130705 in my table, these would not be listed in sys.partition_range_values. I just created an “everything else” bucket in my ssis package just in case I had any dayid values unaccounted for. To get the number of rows for a partition is very easy. The sys.partitions table contains values for each partition. Easy enough to achieve by querying for the object_id and index value of 1 (the clustered index) The final piece of information was the filegroup name. There are 2 options available to get the filegroup name, sys.data_spaces or sys.filegroups. For my query I chose sys.filegroups but really it’s a matter of preference and data needs. In order to bridge between sys.partitions table and either sys.data_spaces or sys.filegroups you need to get the container_id. This can be done by joining sys.allocation_units.container_id to the sys.partitions.hobt_id. sys.allocation_units contains the field data_space_id which then lets you join in either sys.data_spaces or sys.file_groups. The end result is the query below, which typically executes for me in under 1 second. I’ve included the join to sys.filegroups and to sys.dataspaces, and I’ve  just commented out the join sys.filegroups. As I mentioned above, this shaves a good 10-15 minutes off of my original ssis package and is a really easy tweak to get a boost in my ETL time. Enjoy.

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• Package management system corrupted. Cannot install or remove packages. U12.04LTS

  - by user271490

  Having read other posts, I believe that this may be less about samba than about update system. Below is the log file of the failed installation of Samba. I have been trying without success to install/outstall samba so that I could install anything else ... I cannot either install or remove samba using either update-manager or apt-get (nor indeed Software Centre). One of the errors that I have had to correct is the presence after "removal" (failed) of /usr/share/system-config-samba directory which finally allowed itself to be deleted. That, however was then ... I have U12.04LTS. running on release 63 because I allowed the upgrade to 64 this morning which fell over - no output to monitor - obviously even less support for my graphic chip than I am suffering already (see other posts in this forum). According to my interpretation of the dpkg returned errors there may be some problem with the package files, but if this is the case then it is on servers 'main', 'nantes uni fr' and 'best fr' at the very least if not everywhere. The suggestions offered at Package operation failed and elsewhere have not worked for me. This linked post suggests that a similar error is present in other packages, or that the error is in the 'update system' I have tried ... sudo apt-get remove samba ... autoremove ... install samba ... clean ... update -f all of the above In update-manager I have tried the "reload packages list" which fails to terminate because of the error. I have tried to install and remove samba from the software centre ... :( I am at a loss ... I need help, please! Firstly to recover my apt-get/update-manager/Software Centre so that I can at least carry on with my continuing installation - up to communicating with home network hence need for samba - which brings me to my second requirement ... samba. PS is the issue about "MaxReports" associated or apart? UPDATE! Being heartily sick of restarting FF every 5 seconds I thought I'd try again with Chromium ... and got the same errors from dpkg about corrupt compressed package - coincidence? Of course this was no longer in clipboard when I got here because apport has just errored ... AAARRRGGGH!!! Why does every error clear the clipboard? Thanks for any and all help!! installArchives() failed: Preconfiguring packages ... ... snip (Reading database ... ... snip (Reading database ... 184858 files and directories currently installed.) Unpacking samba (from .../samba_2%3a3.6.3-2ubuntu2.10_i386.deb) ... dpkg-deb (subprocess): data: internal gzip read error: ': data error' dpkg-deb: error: subprocess returned error exit status 2 dpkg: error processing /var/cache/apt/archives/samba_2%3a3.6.3-2ubuntu2.10_i386.deb (--unpack): subprocess dpkg-deb --fsys-tarfile returned error exit status 2 No apport report written because MaxReports is reached already Selecting previously unselected package system-config-samba. Unpacking system-config-samba (from .../system-config-samba_1.2.63-0ubuntu5_all.deb) ... Processing triggers for ureadahead ... ureadahead will be reprofiled on next reboot Processing triggers for ufw ... Processing triggers for man-db ... Processing triggers for bamfdaemon ... Rebuilding /usr/share/applications/bamf.index... Processing triggers for desktop-file-utils ... Processing triggers for gnome-menus ... Processing triggers for hicolor-icon-theme ... Errors were encountered while processing: /var/cache/apt/archives/samba_2%3a3.6.3-2ubuntu2.10_i386.deb Error in function: dpkg: dependency problems prevent configuration of system-config-samba: system-config-samba depends on samba; however: Package samba is not installed. dpkg: error processing system-config-samba (--configure): dependency problems - leaving unconfigured

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• Graphics trouble after resuming from hibernate or suspend

  - by Voyagerfan5761

  I have a Dell Inspiron 2650 (with NVidia graphics, using nouveau drivers) that I'm using to try out Ubuntu. It's all great, except that Hibernate and Suspend aren't usable. Yes, I know that questions about power-save issues are rampant in the Linux support universe, but it seems that every time I find a solution it's for a very specific hardware combination and doesn't apply to me. So anyway, here goes. When I resume from either power-saving mode, I'll get graphics problems anywhere on the range from a few scattered random-colored pixels that won't change; all the way to full-screen patterns that don't change as I move the mouse, hit keys on the keyboard, or even bring up the shutdown dialog using the power button. Those full-screen issues (which may involve stripes with random pixels, partial black screen, or both) always end in me forcing the machine to shut down by holding the power button. I haven't done much testing yet to determine what severity level is most commonly associated with each mode, but I do avoid using either power-save option because of these issues. I'll add info on my hardware as I can gather it (no home internet connection, and this laptop is tethered to my desk by a dead battery and casing degradation). Please feel free to request something specific in the question comments. Hardware Info See this hardinfo report for my system's hardware configuration. (No, my username is not "myuser"; I sanitized hardinfo's output before publishing it.) Screenshots These screenshots are from a relatively mild occurrence, which happened after the second hibernation I took that session. The first one worked great, though I used the wireless card and Firefox heavily between the two hibernation attempts. Take a look at what happened when I opened my home directory in Nautilus and scrolled it: See below for the situations I've tested so far. The real trouble comes when the machine resumes to an unusable state; in such cases I can't even unlock the screen or properly reboot, much less take a screenshot. I have a hunch that putting a CD in the drive will cause such major failures, and I will try that at some point; see related question. Situations Tested Maverick (10.10) Suspend Seems to suspend nicely with nothing running Seems to suspend nicely with flash drive plugged in On resume from suspend with no flash drive, Terminal and gedit running: Funky graphics on top of log output, then blank screen with pixelated cursor; no response to power button (normally will shutdown 60 seconds later) Hibernate Seems to hibernate nicely with nothing running Seems to hibernate nicely with a few apps (Terminal, Mouse preferences) running Seems to not hibernate when flash drive plugged in Seems to not hibernate when System Monitor is running Have encountered failed hibernation (after several hours and one successful hibernate/thaw cycle) with no external media connected and no programs running except normal background stuff Natty LiveCD (11.04_2010-12-22) When I tested it, Natty wouldn't stay logged in. It played part of the login sound and then [ OK ] appeared in the top right corner (white-on-black terminal text) for a few seconds. Then it kicked me back to the Unlock screen. It did that four times before I gave up and just tested suspend from the Unlock screen. Suspend Resumed to vertical gray and black lines 2px (?) wide, then shifted to vertical "jail bars" of black over a black screen with above-described random pixels and mouse pointer. No apparent response to input from mouse (clicking randomly). Keyboard and touchpad unrecognized.

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• Need help partitioning when reinstalling Ubuntu 14.04

  - by Chris M.

  I upgraded to 14.04 about a month ago on my HP Mini netbook (about 16 GB hard disk). A few days ago the system crashed (I don't know why but I was using internet at the time). When I restarted the computer, Ubuntu would not load. Instead, I got a message from the BIOS saying Reboot and Select proper Boot device or Insert Boot Media in selected Boot device and press a key I took this to mean that I needed to reinstall 14.04. When I try to reinstall Ubuntu from the USB stick, I choose "Erase disk and install Ubuntu" but then I get a message: Some of the partitions you created are too small. Please make the following partitions at least this large: / 3.3 GB If you do not go back to the partitioner and increase the size of these partitions, the installation may fail. At first I hit Continue to see if it would install anyway, and it gave the message: The attempt to mount a file system with type ext4 in SCSI1 (0,0,0), partition # 1 (sda) at / failed. You may resume partitioning from the partitioning menu. The second time I hit Go Back, and it took me to the following partitioning table: Device Type Mount Point Format Size Used System /dev/sda /dev/sda1 ext4 (checked) 3228 MB Unknown /dev/sda5 swap (not checked) 1063 MB Unknown + - Change New Partition Table... Revert Device for boot loader installation: /dev/sda ATA JM Loader 001 (4.3 GB) At this point I'm not sure what to do. I've never partitioned my hard drive before and I don't want to screw things up. (I'm not particularly tech savvy.) Can you instruct me what I should do. (P.S. I'm afraid the table might not appear as I typed it in.) Results from fdisk: ubuntu@ubuntu:~$ sudo fdisk -l Disk /dev/sda: 4294 MB, 4294967296 bytes 255 heads, 63 sectors/track, 522 cylinders, total 8388608 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/sda doesn't contain a valid partition table Disk /dev/sdb: 7860 MB, 7860125696 bytes 155 heads, 31 sectors/track, 3194 cylinders, total 15351808 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0009a565 Device Boot Start End Blocks Id System /dev/sdb1 * 2768 15351807 7674520 b W95 FAT32 ubuntu@ubuntu:~$ Here is what it displays when I open the Disks utility (I tried the screenshot terminal command you suggested but it didn't seem to do anything): 4.3 GB Hard Disk /dev/sda Model: JM Loader 001 (01000001) Size: 4.3 GB (4,294,967,296 bytes) Serial Number: 01234123412341234 Assessment: SMART is not supported Volumes Size: 4.3 GB (4,294,967,296 bytes) Device: /dev/sda Contents: Unknown (There is a button in the utility that when you click it gives the following options: Format... Create Disk Image... Restore Disk Image... Benchmark but SMART Data & Self-Tests... is dimmed out) When I hit F9 Change Boot Device Order, it shows the hard drive as: SATA:PM-JM Loader 001 When I hit F10 to get me into the BIOS Setup Utility, under Diagnostic it shows: Primary Hard Disk Self Test Not Support NetworkManager Tool State: disconnected Device: eth0 Type: Wired Driver: atl1c State: unavailable Default: no HW Address: 00:26:55:B0:7F:0C Capabilities: Carrier Detect: yes Wired Properties Carrier: off When I run command lshw -C network, I get: WARNING: you should run this program as super-user. *-network description: Network controller product: BCM4312 802.11b/g LP-PHY vendor: Broadcom Corporation physical id: 0 bus info: pci@0000:01:00.0 version: 01 width: 64 bits clock: 33MHz capabilities: bus_master cap_list configuration: driver=b43-pci-bridge latency=0 resources: irq:16 memory:feafc000-feafffff *-network description: Ethernet interface product: AR8132 Fast Ethernet vendor: Qualcomm Atheros physical id: 0 bus info: pci@0000:02:00.0 logical name: eth0 version: c0 serial: 00:26:55:b0:7f:0c capacity: 100Mbit/s width: 64 bits clock: 33MHz capabilities: bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=atl1c driverversion=1.0.1.1-NAPI latency=0 link=no multicast=yes port=twisted pair resources: irq:43 memory:febc0000-febfffff ioport:ec80(size=128) WARNING: output may be incomplete or inaccurate, you should run this program as super-user.

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• Public Sector FMW Customer Tech Day in Reston, Tuesday Oct 7th

  - by BPMWarrior

  Have your heard? There is another PS FMW Customer Tech Day scheduled in the Oracle Reston office!                                                                                          Fusion Middleware Customer Tech Day                                                          October 7, 2014                                   Please join Oracle & Sofbang on Tuesday October 7th for our second Public Sector Oracle Fusion Middleware (OFMW) Customer Tech Day in Reston.   This Tech Day is designed with you the customer in mind. Come learn and share with other customers. This event will be centered on Mobility, App Advantage, WebCenter, SOA, BPM, Security and FMWaaS.   Sofbang enables customers to create, integrate and run agile intelligent business applications leveraging Oracle Fusion Middleware. Based out of Chicago, IL, Sofbang is recognized as an Oracle Platinum level Partner in the Oracle Partner Network. For more information on Sofbang, please visit www.sofbang.com   To confirm your attendance at this Event or for more information, please email [email protected]                                              

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• Investigating on xVelocity (VertiPaq) column size

  - by Marco Russo (SQLBI)

    In January I published an article about how to optimize high cardinality columns in VertiPaq. In the meantime, VertiPaq has been rebranded to xVelocity: the official name is now “xVelocity in-memory analytics engine (VertiPaq)” but using xVelocity and VertiPaq when we talk about Analysis Services has the same meaning. In this post I’ll show how to investigate on columns size of an existing Tabular database so that you can find the most important columns to be optimized. A first approach can be looking in the DataDir of Analysis Services and look for the folder containing the database. Then, look for the biggest files in all subfolders and you will find the name of a file that contains the name of the most expensive column. However, this heuristic process is not very optimized. A better approach is using a DMV that provides the exact information. For example, by using the following query (open SSMS, open an MDX query on the database you are interested to and execute it) you will see all database objects sorted by used size in a descending way. SELECT * FROM $SYSTEM.DISCOVER_STORAGE_TABLE_COLUMN_SEGMENTS ORDER BY used_size DESC You can look at the first rows in order to understand what are the most expensive columns in your tabular model. The interesting data provided are: TABLE_ID: it is the name of the object – it can be also a dictionary or an index COLUMN_ID: it is the column name the object belongs to – you can also see ID_TO_POS and POS_TO_ID in case they refer to internal indexes RECORDS_COUNT: it is the number of rows in the column USED_SIZE: it is the used memory for the object By looking at the ration between USED_SIZE and RECORDS_COUNT you can understand what you can do in order to optimize your tabular model. Your options are: Remove the column. Yes, if it contains data you will never use in a query, simply remove the column from the tabular model Change granularity. If you are tracking time and you included milliseconds but seconds would be enough, round the data source column to the nearest second. If you have a floating point number but two decimals are good enough (i.e. the temperature), round the number to the nearest decimal is relevant to you. Split the column. Create two or more columns that have to be combined together in order to produce the original value. This technique is described in VertiPaq optimization article. Sort the table by that column. When you read the data source, you might consider sorting data by this column, so that the compression will be more efficient. However, this technique works better on columns that don’t have too many distinct values and you will probably move the problem to another column. Sorting data starting from the lower density columns (those with a few number of distinct values) and going to higher density columns (those with high cardinality) is the technique that provides the best compression ratio. After the optimization you should be able to reduce the used size and improve the count/size ration you measured before. If you are interested in a longer discussion about internal storage in VertiPaq and you want understand why this approach can save you space (and time), you can attend my 24 Hours of PASS session “VertiPaq Under the Hood” on March 21 at 08:00 GMT.

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• Head in the Clouds

  - by Tony Davis

  We're just past the second anniversary of the launch of Windows Azure. A couple of years' experience with Azure in the industry has provided some obvious success stories, but has deflated some of the initial marketing hyperbole. As a general principle, Azure seems to work well in providing a Service-Oriented Architecture for services in enterprises that suffer wide fluctuations in demand. Instead of being obliged to provide hardware sufficient for the occasional peaks in demand, one can hire capacity only when it is needed, and the cost of hosting an application is no longer a capital cost. It enables companies to avoid having to scale out hardware for peak periods only to see it underused for the rest of the time. A customer-facing application such as a concert ticketing system, which suffers high demand in short, predictable bursts of activity, is a great example of an application that would work well in Azure. However, moving existing applications to Azure isn't something to be done on impulse. Unless your application is .NET-based, and consists of 'stateless' components that communicate via queues, you are probably in for a lot of redevelopment work. It makes most sense for IT departments who are already deep in this .NET mindset, and who also want 'grown-up' methods of staging, testing, and deployment. Azure fits well with this culture and offers, as a bonus, good Visual Studio integration. The most-commonly stated barrier to porting these applications to Azure is the problem of reconciling the use of the cloud with legislation for data privacy and security. Putting databases in the cloud is a sticky issue for many and impossible for some due to compliance and security issues, the need for direct control over data, and so on. In the face of feedback from the early adopters of Azure, Microsoft has broadened the architectural choices to cater for a wide range of requirements. As well as SQL Azure Database (SAD) and Azure storage, the unstructured 'BLOB and Entity-Attribute-Value' NoSQL storage alternative (which equates more closely with folders and files than a database), Windows Azure offers a wide range of storage options including use of services such as oData: developers who are programming for Windows Azure can simply choose the one most appropriate for their needs. Secondly, and crucially, the Windows Azure architecture allows you the freedom to produce hybrid applications, where only those parts that need cloud-based hosting are deployed to Azure, whereas those parts that must unavoidably be hosted in a corporate datacenter can stay there. By using a hybrid architecture, it will seldom, if ever, be necessary to move an entire application to the cloud, along with personal and financial data. For example that we could port to Azure only put those parts of our ticketing application that capture and process tickets orders. Once an order is captured, the financial side can be processed in our own data center. In short, Windows Azure seems to be a very effective way of providing services that are subject to wide but predictable fluctuations in demand. Have you come to the same conclusions, or do you think I've got it wrong? If you've had experience with Azure, would you recommend it? It would be great to hear from you. Cheers, Tony.

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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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• Why won't my Broadcom BCM4312 LP-PHY work with the STA driver?

  - by Jackson Taylor

  I tried the steps here for a 4312: https://help.ubuntu.com/community/WifiDocs/Driver/bcm43xx Both of these: sudo modprobe -r b43 ssb wl sudo modprobe wl return: FATAL: Module wl not found. FATAL: Error running install command for wl (this one is only for the second one actually) I tried the broadcom-sta, didn't work. What's confusing is down below in the next steps for STA with internet access it says to use the bcmwl one. So I install that and it succeeds but with some errors: sudo apt-get install bcmwl-kernel-source Reading package lists... Done Building dependency tree Reading state information... Done The following package was automatically installed and is no longer required: module-assistant Use 'apt-get autoremove' to remove it. The following NEW packages will be installed: bcmwl-kernel-source 0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded. Need to get 0 B/1,181 kB of archives. After this operation, 3,609 kB of additional disk space will be used. Selecting previously unselected package bcmwl-kernel-source. (Reading database ... 168005 files and directories currently installed.) Unpacking bcmwl-kernel-source (from .../bcmwl-kernel-source_5.100.82.112+bdcom-0ubuntu3_amd64.deb) ... Setting up bcmwl-kernel-source (5.100.82.112+bdcom-0ubuntu3) ... Loading new bcmwl-5.100.82.112+bdcom DKMS files... Building only for 3.5.0-21-generic Building for architecture x86_64 Module build for the currently running kernel was skipped since the kernel source for this kernel does not seem to be installed. ERROR: Module b43 does not exist in /proc/modules ERROR: Module b43legacy does not exist in /proc/modules ERROR: Module ssb does not exist in /proc/modules ERROR: Module bcm43xx does not exist in /proc/modules ERROR: Module brcm80211 does not exist in /proc/modules ERROR: Module brcmfmac does not exist in /proc/modules ERROR: Module brcmsmac does not exist in /proc/modules ERROR: Module bcma does not exist in /proc/modules FATAL: Module wl not found. FATAL: Error running install command for wl update-initramfs: deferring update (trigger activated) Processing triggers for initramfs-tools ... update-initramfs: Generating /boot/initrd.img-3.5.0-21-generic jtaylor991@jtaylor991-whiteHP:~$ sudo modprobe wl FATAL: Module wl not found. FATAL: Error running install command for wl Then I do the modprobe wl commands listed above and it gives the above listed errors. It didn't work with the broadcom-sta driver either. I installed the b43 ones but nothing happened, and I don't know why so those are still installed. firmware-b43legacy-installer, b43-fwcutter and firmware-b43-lpphy-installer (yes it is a LP-PHY) are currently installed. If I go into System Settings Software Sources Additional Drivers it says "Using Broadcom 802.11 Linux STA wireless driver source from bcmwl-kernel-source (proprietary) But bcmwl-kernel-source isn't installed. I could try again but I remember rebooting and it still said this. What's funny is it found wireless networks during the Ubuntu setup/installation, I don't remember if I got it to connect or not though. I think it kept asking for a password when I put it in (yes it was right I showed password and looked at it) so I just ignored it. But right now the Enable Wireless option in the top right is just gone, it's just Enable Networking and I'm on ethernet on this HP Pavilion dv4-1435dx right here. If I run rfkill list it shows: 0: hp-wifi: Wireless LAN Soft blocked: no Hard blocked: no It was hard blocked at the beginning but unblocking it makes no change. Also it's a touch sensitive button, and it appears to be always orange no matter if it's enabled or not because when I touch it the hard blocked changes between yes and no in rfkill list. I think it was blue for a minute at one point. What is going on?!?! Help me! Lol, thanks for any and all of your time guys. Oh yeah this is Ubuntu 12.10 fresh install.

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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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• Identity in .NET 4.5&ndash;Part 2: Claims Transformation in ASP.NET (Beta 1)

  - by Your DisplayName here!

  In my last post I described how every identity in .NET 4.5 is now claims-based. If you are coming from WIF you might think, great – how do I transform those claims? Sidebar: What is claims transformation? One of the most essential features of WIF (and .NET 4.5) is the ability to transform credentials (or tokens) to claims. During that process the “low level” token details are turned into claims. An example would be a Windows token – it contains things like the name of the user and to which groups he belongs to. That information will be surfaced as claims of type Name and GroupSid. Forms users will be represented as a Name claim (all the other claims that WIF provided for FormsIdentity are gone in 4.5). The issue here is, that your applications typically don’t care about those low level details, but rather about “what’s the purchase limit of alice”. The process of turning the low level claims into application specific ones is called claims transformation. In pre-claims times this would have been done by a combination of Forms Authentication extensibility, role manager and maybe ASP.NET profile. With claims transformation all your identity gathering code is in one place (and the outcome can be cached in a single place as opposed to multiple ones). The structural class to do claims transformation is called ClaimsAuthenticationManager. This class has two purposes – first looking at the incoming (low level) principal and making sure all required information about the user is present. This is your first chance to reject a request. And second – modeling identity information in a way it is relevant for the application (see also here). This class gets called (when present) during the pipeline when using WS-Federation. But not when using the standard .NET principals. I am not sure why – maybe because it is beta 1. Anyhow, a number of people asked me about it, and the following is a little HTTP module that brings that feature back in 4.5. public class ClaimsTransformationHttpModule : IHttpModule {     public void Dispose()     { }     public void Init(HttpApplication context)     {         context.PostAuthenticateRequest += Context_PostAuthenticateRequest;     }     void Context_PostAuthenticateRequest(object sender, EventArgs e)     {         var context = ((HttpApplication)sender).Context;         // no need to call transformation if session already exists         if (FederatedAuthentication.SessionAuthenticationModule != null &&             FederatedAuthentication.SessionAuthenticationModule.ContainsSessionTokenCookie(context.Request.Cookies))         {             return;         }         var transformer = FederatedAuthentication.FederationConfiguration.IdentityConfiguration.ClaimsAuthenticationManager;         if (transformer != null)         {             var transformedPrincipal = transformer.Authenticate(context.Request.RawUrl, context.User as ClaimsPrincipal);             context.User = transformedPrincipal;             Thread.CurrentPrincipal = transformedPrincipal;         }     } } HTH

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• Omni-directional light shadow mapping with cubemaps in WebGL

  - by Winged

  First of all I must say, that I have read a lot of posts describing an usage of cubemaps, but I'm still confused about how to use them. My goal is to achieve a simple omni-directional (point) light type shading in my WebGL application. I know that there is a lot more techniques (like using Two-Hemispheres or Camera Space Shadow Mapping) which are way more efficient, but for an educational purpose cubemaps are my primary goal. Till now, I have adapted a simple shadow mapping which works with spotlights (with one exception: I don't know how to cut off the glitchy part beyond the reach of a single shadow map texture): glitchy shadow mapping<<< So for now, this is how I understand the usage of cubemaps in shadow mapping: Setup a framebuffer (in case of cubemaps - 6 framebuffers; 6 instead of 1 because every usage of framebufferTexture2D slows down an execution which is nicely described here <<<) and a texture cubemap. Also in WebGL depth components are not well supported, so I need to render it to RGBA first. this.texture = gl.createTexture(); gl.bindTexture(gl.TEXTURE_CUBE_MAP, this.texture); gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MIN_FILTER, gl.LINEAR); gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MAG_FILTER, gl.LINEAR); for (var face = 0; face < 6; face++) gl.texImage2D(gl.TEXTURE_CUBE_MAP_POSITIVE_X + face, 0, gl.RGBA, this.size, this.size, 0, gl.RGBA, gl.UNSIGNED_BYTE, null); gl.bindTexture(gl.TEXTURE_CUBE_MAP, null); this.framebuffer = []; for (face = 0; face < 6; face++) { this.framebuffer[face] = gl.createFramebuffer(); gl.bindFramebuffer(gl.FRAMEBUFFER, this.framebuffer[face]); gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_CUBE_MAP_POSITIVE_X + face, this.texture, 0); gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, this.depthbuffer); var e = gl.checkFramebufferStatus(gl.FRAMEBUFFER); // Check for errors if (e !== gl.FRAMEBUFFER_COMPLETE) throw "Cubemap framebuffer object is incomplete: " + e.toString(); } Setup the light and the camera (I'm not sure if should I store all of 6 view matrices and send them to shaders later, or is there a way to do it with just one view matrix). Render the scene 6 times from the light's position, each time in another direction (X, -X, Y, -Y, Z, -Z) for (var face = 0; face < 6; face++) { gl.bindFramebuffer(gl.FRAMEBUFFER, shadow.buffer.framebuffer[face]); gl.viewport(0, 0, shadow.buffer.size, shadow.buffer.size); gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT); camera.lookAt( light.position.add( cubeMapDirections[face] ) ); scene.draw(shadow.program); } In a second pass, calculate the projection a a current vertex using light's projection and view matrix. Now I don't know If should I calculate 6 of them, because of 6 faces of a cubemap. ScaleMatrix pushes the projected vertex into the 0.0 - 1.0 region. vDepthPosition = ScaleMatrix * uPMatrixFromLight * uVMatrixFromLight * vWorldVertex; In a fragment shader calculate the distance between the current vertex and the light position and check if it's deeper then the depth information read from earlier rendered shadow map. I know how to do it with a 2D Texture, but I have no idea how should I use cubemap texture here. I have read that texture lookups into cubemaps are performed by a normal vector instead of a UV coordinate. What vector should I use? Just a normalized vector pointing to the current vertex? For now, my code for this part looks like this (not working yet): float shadow = 1.0; vec3 depth = vDepthPosition.xyz / vDepthPosition.w; depth.z = length(vWorldVertex.xyz - uLightPosition) * linearDepthConstant; float shadowDepth = unpack(textureCube(uDepthMapSampler, vWorldVertex.xyz)); if (depth.z > shadowDepth) shadow = 0.5; Could you give me some hints or examples (preferably in WebGL code) how I should build it?

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• Cloud Computing Pricing - It's like a Hotel

  - by BuckWoody

  I normally don't go into the economics or pricing side of Distributed Computing, but I've had a few friends that have been surprised by a bill lately and I wanted to quickly address at least one aspect of it. Most folks are used to buying software and owning it outright - like buying a car. We pay a lot for the car, and then we use it whenever we want. We think of the "cloud" services as a taxi - we'll just pay for the ride we take an no more. But it's not quite like that. It's actually more like a hotel. When you subscribe to Azure using a free offering like the MSDN subscription, you don't have to pay anything for the service. But when you create an instance of a Web or Compute Role, Storage, that sort of thing, you can think of the idea of checking into a hotel room. You get the key, you pay for the room. For Azure, using bandwidth, CPU and so on is billed just like it states in the Azure Portal. so in effect there is a cost for the service and then a cost to use it, like water or power or any other utility. Where this bit some folks is that they created an instance, played around with it, and then left it running. No one was using it, no one was on - so they thought they wouldn't be charged. But they were. It wasn't much, but it was a surprise.They had the hotel room key, but they weren't in the room, so to speak. To add to their frustration, they had to talk to someone on the phone to cancel the account. I understand the frustration. Although we have all this spelled out in the sign up area, not everyone has the time to read through all that. I get that. So why not make this easier? As an explanation, we bill for that time because the instance is still running, and we have to tie up resources to be available the second you want them, and that costs money. As far as being able to cancel from the portal, that's also something that needs to be clearer. You may not be aware that you can spin up instances using code - and so cancelling from the Portal would allow you to do the same thing. Since a mistake in code could erase all of your instances and the account, we make you call to make sure you're you and you really want to take it down. Not a perfect system by any means, but we'll evolve this as time goes on. For now, I wanted to make sure you're aware of what you should do. By the way, you don't have to cancel your whole account not to be billed. Just delete the instance from the portal and you won't be charged. You don't have to call anyone for that. And just FYI - you can download the SDK for Azure and never even hit the online version at all for learning and playing around. No sign-up, no credit card, PO, nothing like that. In fact, that's how I demo Azure all the time. Everything runs right on your laptop in an emulated environment.  

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