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• Criteria for a programming language to be considered "mature"

  - by Giorgio

  I was recently reading an answer to this question, and I was struck by the statement "The language is mature". So I was wondering what we actually mean when we say that "A programming language is mature"? Normally, a programming language is initially developed out of a need, e.g. Try out / implement a new programming paradigm or a new combination of features that cannot be found in existing languages. Try to solve a problem or overcome a limitation of an existing language. Create a language for teaching programming. Create a language that solves a particular class of problems (e.g. concurrency). Create a language and an API for a special application field, e.g. the web (in this case the language might reuse a well-known paradigm, but the whole API must be new). Create a language to push your competitor out of the market (in this case the creator might want the new language to be very similar to an existing one, in order to attract developers to the new programming language and platform). Regardless of what the original motivation and scenario in which a language has been created, eventually some languages are considered mature. In my intuition, this means that the language has achieved (at least one of) its goals, e.g. "We can now use language X as a reliable tool for writing web applications." This is however a bit vague, so I wanted to ask what you consider the most important criteria (if any) that are applied when saying that a language is mature. IMPORTANT NOTE This question is (on purpose) language-agnostic because I am only interested in general criteria. Please write only language-agnostic answers and comments! I am not asking whether any specific "language X is mature" or "which programming languages can be considered mature", or whether "language X is more mature than language Y": please avoid posting any opinions or reference about any specific languages because these are out of the scope of this question. EDIT To make the question more precise, by criteria I mean such things as "tool support", "adoption by the industry", "stability", "rich API", "large user community", "successful application record", "standardization", "clean and uniform semantics", and so on.

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• StringBuffer behavior in LWJGL

  - by Michael Oberlin

  Okay, I've been programming in Java for about ten years, but am entirely new to LWJGL. I have a specific problem whilst attempting to create a text console. I have built a class meant to abstract input polling to it, which (in theory) captures key presses from the Keyboard object and appends them to a StringBuilder/StringBuffer, then retrieves the completed string after receiving the ENTER key. The problem is, after I trigger the String return (currently with ESCAPE), and attempt to print it to System.out, I consistently get a blank line. I can get an appropriate string length, and I can even sample a single character out of it and get complete accuracy, but it never prints the actual string. I could swear that LWJGL slipped some kind of thread-safety trick in while I wasn't looking. Here's my code: static volatile StringBuffer command = new StringBuffer(); @Override public void chain(InputPoller poller) { this.chain = poller; } @Override public synchronized void poll() { //basic testing for modifier keys, to be used later on boolean shift = false, alt = false, control = false, superkey = false; if(Keyboard.isKeyDown(Keyboard.KEY_LSHIFT) || Keyboard.isKeyDown(Keyboard.KEY_RSHIFT)) shift = true; if(Keyboard.isKeyDown(Keyboard.KEY_LMENU) || Keyboard.isKeyDown(Keyboard.KEY_RMENU)) alt = true; if(Keyboard.isKeyDown(Keyboard.KEY_LCONTROL) || Keyboard.isKeyDown(Keyboard.KEY_RCONTROL)) control = true; if(Keyboard.isKeyDown(Keyboard.KEY_LMETA) || Keyboard.isKeyDown(Keyboard.KEY_RMETA)) superkey = true; while(Keyboard.next()) if(Keyboard.getEventKeyState()) { command.append(Keyboard.getEventCharacter()); } if (Framework.isConsoleEnabled() && Keyboard.isKeyDown(Keyboard.KEY_ESCAPE)) { System.out.println("Escape down"); System.out.println(command.length() + " characters polled"); //works System.out.println(command.toString().length()); //works System.out.println(command.toString().charAt(4)); //works System.out.println(command.toString().toCharArray()); //blank line! System.out.println(command.toString()); //blank line! Framework.disableConsole(); } //TODO: Add command construction and console management after that } } Maybe the answer's obvious and I'm just feeling tired, but I need to walk away from this for a while. If anyone sees the issue, please let me know. This machine is running the latest release of Java 7 on Ubuntu 12.04, Mate desktop environment. Many thanks.

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• How can I create a flexible system for tiling a 2D RPG map?

  - by CptSupermrkt

  Using libgdx here. I've just finished learning some of the basics of creating a 2D environment and using an OrthographicCamera to view it. The tutorials I went through, however, hardcoded their tiled map in, and none made mention of how to do it any other way. By tiled map, I mean like Final Fantasy 1, where the world map is a grid of squares, each with a different texture. So for example, I've got a 6 tile x 6 tile map, using the following code: Array<Tile> tiles = new Array<Tile>(); tiles.add(new Tile(new Vector2(0,5), TileType.FOREST)); tiles.add(new Tile(new Vector2(1,5), TileType.FOREST)); tiles.add(new Tile(new Vector2(2,5), TileType.FOREST)); tiles.add(new Tile(new Vector2(3,5), TileType.GRASS)); tiles.add(new Tile(new Vector2(4,5), TileType.STONE)); tiles.add(new Tile(new Vector2(5,5), TileType.STONE)); //... x5 more times. Given the random nature of the environment, for loops don't really help as I have to start and finish a loop before I was able to do enough to make it worth setting up the loop. I can see how a loop might be helpful for like tiling an ocean or something, but not in the above case. The above code DOES get me my final desired output, however, if I were to decide I wanted to move a piece or swap two pieces out, oh boy, what a nightmare, even with just a 6x6 test piece, much less a 1000x1000 world map. There must be a better way of doing this. Someone on some post somewhere (can't find it now, of course) said to check out MapEditor. Looks legit. The question is, if that is the answer, how can I make something in MapEditor and have the output map plug in to a variable in my code? I need the tiles as objects in my code, because for example, I determine whether or not a tile is can be passed through or collided with based on my TileTyle enum variable. Are there alternative/language "native" (i.e. not using an outside tool) methods to doing this?

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• Cannot install "ATI/AMD proprietary FGLRX graphics driver" (SystemError)

  - by Fisherman John

  I have just installed a fresh copy of 12.04.1 64bit. I formatted my PC completely and enabled updates during the installation. After the installation was complete, I went on updating my software. However, when I wanted to install the additional drivers using the Additional Drivers tool (namely "ATI/AMD proprietary FGLRX graphics driver"), it gave me this error: SystemError: E:Unable to correct problems, you have held broken packages. The same error shows up if I try installing the post-release updates driver. Installing the drivers from the terminal results in this output: XXXXXX:~$ sudo apt-get install fglrx [sudo] password for XXXXX: Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: fglrx : Depends: lib32gcc1 but it is not going to be installed Depends: libc6-i386 but it is not going to be installed E: Unable to correct problems, you have held broken packages." I get this using "sudo apt-get update": http://pastebin.com/AWAtDXjY But "sudo apt-get install fglrx" still get me this error: http://pastebin.com/RYM55bVN & "sudo apt-get -f install fglrx" gives me this error: http://pastebin.com/xxekajvP Any help would be greatly appreciated. (Please note that I'm new to Linux, coming directly from Windows. I have tried Ubuntu twice or so before, but it was not for a long period of time. The drivers got installed smoothly the few times I've tried Ubuntu, but post-release updates never worked for me.) [I am going to work now, so I can only answer from my phone. Can't really test any new solutions you may give me until ~10 hours from now on. Maybe more.] @stonedsquirrel When I try to run that command, I get this error: "XXXXXX:~$ sudo apt-get install fglrx [sudo] password for XXXXX: Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: fglrx : Depends: lib32gcc1 but it is not going to be installed Depends: libc6-i386 but it is not going to be installed E: Unable to correct problems, you have held broken packages." ie. I get the same error. ( I am Fisherman John, dunno how to login & thereby respond to your comment again _ )

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• Unable to boot into 11.10 in normal (get a black screen) OR recovery (get just a flashing cursor, no cli)

  - by user1092284

  Okay, so I had a dual boot of Tango Studio (based on Ubuntu 10.04) and Windows XP. Yesterday I downloaded the .iso for Ubuntu 11.10 and attempted to install from a USB (my BIOS won't normally boot from USB but I had PLOP boot manager on a CD). I booted up Ubuntu from the USB and then from there formatted the partition with Tango on and installed Ubuntu 11.10. On booting up I came into Grub rescue mode. So I booted up from the USB again and used boot-repair to reinstall Grub. After this I would see the normal Grub menu, but on choosing Ubuntu I would come to a black screen. On choosing recovery mode it would begin starting normally with no obvious errors but instead of coming to a cli I would just get a blank screen with a flashing cursor on the top left, not accepting any input. I have since reformatted and reinstalled from a CD rather than USB and had the exact same problem. I used boot-repair again and the result is the same. Output of the most recent boot-repair is at http://paste.ubuntu.com/869805/ I have also tried editing the ubuntu grub entry and replacing quiet with text nomodeset as I saw in an answer to another question. This got me a bit further - I saw the purple ubuntu loading screen but still came to a blank screen after that. Anyway, in most of the other questions in which that is brought up the user is still able to boot into recovery, while I am not. Can anyone help? Thanks in advance, let me know if there's any more info I need to provide! EDIT FOR MORE INFO: I read something saying it's quiet splash that should be replaced with nomodeset. Earlier I had left splash in the line. So i tried it this way and it froze after displaying the following text: fsck from util-linux 2.19.1 mountall: Plymouth command failed mountall: Disconnected from Plymouth /dev/sda5:clean, 139359/1741488 files, 745830/6961125 blocks From a bit of googling it doesn't look like plymouth is essential, but I've checked and I do have the most current versions of mountall and plymouth installed so I don't know why there's a problem EDIT FOR MORE INFO AGAIN: I used dkpg --reconfigure plymouth cause I saw it mentioned in another forum and it still says plymouth command failed on boot

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• Simulate 'Shock absorbtion' with tire rubber in PhysX (2.8.x)

  - by Mungoid

  This is a kinda tricky question and I fear there is no easy enough solution, but I figured I'd hit SE up before giving up on it and just doing what I can. A machine I am working on has no suspension or shocks or springs of any sort in the real machine, so you would think that when it drives over bumps, it would shake like crazy but because its tires (6 of them) are quite large they seem to absorb a lot of shock from the bumps. Part of this is because the machine is around 30k lbs and it just smashes/compresses any bumps in the ground down (This is another issue im still working on) and the other part is that the tires seem to have a lot of flex to them with a lot of air as well. So my current task is to simulate shock absorption in physx without visibly separating the tires from the spindle/axle.. I have been messing with all kinds of NxMaterial, NxSpring, Joints, etc. and have had no luck getting this to work. The main problem is that the spindle attached to the tire is directly in the center and the axle is basically solidly attached to the chassis, so if i give it any spring or suspension travel, that spindle on the tires will move upwards or downwards, looking very odd because now its not any longer in the center of the tire. I tried giving it a higher restitution but that just makes it bouncy without any shock absorption. Another avenue I am messing with is to actively smooth the terrain in front of the tires so that before it hits a bumpy patch, that patch is smoothed and it doesn't bounce. The only issue with this is that it is pretty expensive to do with 6 tires, high tesselation of the terrain and other complex things going on at the same time in this simulation. I am still working on this but I am hoping to mix and match a few different aspects to get the best possible outcome. This is a bit of a complex issue so I'm not expecting anyone to have a definitive answer, just hoping someone may think of something I haven't =-) -Side note: Yes i know PhysX 2.8.x is quite outdated but we have to stick with it for this implementation. We are in the process of going to another physics engine but it is out of scope to apply that engine to this project.

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• How to implement a component based system for items in a web game.

  - by Landstander

  Reading several other questions and answers on using a component based system to define items I want to use one for the items and spells in a web game written in PHP. I'm just stuck on the implementation. I'm going to use a DB schema suggested in this series (part 5 describes the schema); http://t-machine.org/index.php/2007/09/03/entity-systems-are-the-future-of-mmog-development-part-1/ This means I'll have an items table with generic item properties, a table listing all of the components for an item and finally records in each component table used to make up the item. Assuming I can select the first two together in a single query, I'm still going to do N queries for each component type. I'm kind of fine with this because I can cache the data into memcache and check there first before doing any queries. I'll need to build up the items on every request they are used in so the implementation needs to be on the lean side even if they're pulled from memcache. But right there is where I feel confident about implementing a component system for my items ends. I figure I'd need to bring attributes and behaviors into the container from each component it uses. I'm just not sure how to do that effectively and not end up writing a lot of specialized code to deal with each component. For example an AttackComponent might need to know how to filter targets inside of a battle context and also maybe provide an attack behavior. That same item might also have a UsableComponent which allows the item to be used and apply some effect onto a different set of targets filtered differently from the same battle context. Then not every part of an item is an active part, an AttributeBonusComponent might need to only kick in when the item is in an equipped state or when displaying the item details page. Ultimately, how should I bring all of the components together into the container so when I use an item as a weapon I get the correct list of targets? Know when a weapon can also be used as an item? Or to apply the bonuses the item provides to a character object? I feel like I've gone too far down the rabbit hole and I can't grasp onto the simple solution in front of me. (If that makes any sense at all.) Likewise if I were to implement the best answer from here I feel like I'd have a lot of the same questions. How to model multiple "uses" (e.g. weapon) for usable-inventory/object/items (e.g. katana) within a relational database.

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• Java Grade Calculator program for class kepp geting the error "Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException." [migrated]

  - by user2880621

  this is my first question I've posted. I've used this site to look at other questions to help with similar problems I've had. After some cursory looking I couldn't find quite the answer I was looking for so I decided to finally succumb and create an account. I am fairly new to java, only a few weeks into my first class. Anyway, my project is to create a program which takes any amount of students and their grades, and then assign them a letter grade. The catch is, however, that it is on a sort of curve and the other grades' letter are dependent on the the highest. Anything equal to or 10 points below the best grade is an a, anything 11-20 points below is a b, and so on. I am to use an array, but I get this error when ran "Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException." I will go ahead and post my code down below. Thanks for any advice you may be able to give. package grade.calculator; import java.util.Scanner; /** * * @author nichol57 */ public class GradeCalculator { /** * @param args the command line arguments */ public static void main(String[] args) { Scanner input = new Scanner(System.in); System.out.println("Enter the number of students"); int number = input.nextInt(); double[]grades = new double [number]; for (int J = number; J >=0; J--) { System.out.println("Enter the students' grades"); grades[J] = input.nextDouble(); } double best = grades[0]; for (int J = 1; J < number; J++) { if (grades[J] >= best){ best = grades[J]; } } for (int J = 0;J < number; J++){ if (grades[J] >= best - 10){ System.out.println("Student " + J + " score is " + grades[J] + " and grade is " + "A"); } else if (grades[J] >= best - 20){ System.out.println("Student " + J + " score is " + grades[J] + " and grade is " + "B"); } else if (grades[J] >= best - 30) { System.out.println("Student " + J + " score is " + grades[J] + " and grade is " + "C"); } else if (grades[J] >= best - 40) { System.out.println("Student " + J + " score is " + grades[J] + " and grade is " + "D"); } else { System.out.println("Student " + J + " score is " + grades[J] + " and grade is " + "F"); } } // end for loop for output }// end main method }

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• How to synchronize the ball in a network pong game?

  - by Thaars

  I’m developing a multiplayer network pong game, my first game ever. The current state is, I’ve running the physic engine with the same configurations on the server and the clients. The own paddle movement is predicted and get just confirmed by the authoritative server. Is a difference detected between them, I correct the position at the client by interpolation. The opponent paddle is also interpolated 200ms to 100ms in the past, because the server is broadcasting snapshots every 100ms to each client. So far it works very well, but now I have to simulate the ball and have a problem to understanding the procedure. I’ve read Valve’s (and many other) articles about fast-paced multiplayer several times and understood their approach. Maybe I can compare my ball with their bullets, but their advantage is, the bullets are not visible. When I have to display the ball, and see my paddle in the present, the opponent in the past and the server is somewhere between it, how can I synchronize the ball over all instances and ensure, that it got ever hit by the paddle even if the paddle is fast moving? Currently my ball’s position is simply set by a server update, so it can happen, that the ball bounces back, even if the paddle is some pixel away (because of a delayed server position). Until now I’ve got no synced clock over all instances. I’m sending a client step index with each update to the server. If the server did his job, he sends the snapshot with the last step index of each client back to the clients. Now I’m looking for the stored position at the returned step index and compare them. Do I need a common clock to sync the ball? EDIT: I've tried to sync a common clock for the server and all clients with a timestamp. But I think it's better to use an own stepping instead of a timestamp (so I don't need to calculate with the ping and so on - and the timestamp will never be exact). The physics are running 60 times per second and now I use this for keeping them synchronized. Is that a good way? When the ball gets calculated by each client, the angle after bouncing can differ because of the different position of the paddles (the opponent is 200ms in the past). When the server is sending his ball position, velocity and angle (because he knows the position of each paddle and is authoritative), the ball could be in a very different position because of the different angles after bouncing (because the clients receive the server data after 100ms). How is it possible to interpolate such a huge difference? I posted this question some days ago at stackoverflow, but got no answer yet. Maybe this is the better place for this question.

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• "Whole-team" C++ features?

  - by Blaisorblade

  In C++, features like exceptions impact your whole program: you can either disable them in your whole program, or you need to deal with them throughout your code. As a famous article on C++ Report puts it: Counter-intuitively, the hard part of coding exceptions is not the explicit throws and catches. The really hard part of using exceptions is to write all the intervening code in such a way that an arbitrary exception can propagate from its throw site to its handler, arriving safely and without damaging other parts of the program along the way. Since even new throws exceptions, every function needs to provide basic exception safety — unless it only calls functions which guarantee throwing no exception — unless you disable exceptions altogether in your whole project. Hence, exceptions are a "whole-program" or "whole-team" feature, since they must be understood by everybody in a team using them. But not all C++ features are like that, as far as I know. A possible example is that if I don't get templates but I do not use them, I will still be able to write correct C++ — or will I not?. I can even call sort on an array of integers and enjoy its amazing speed advantage wrt. C's qsort (because no function pointer is called), without risking bugs — or not? It seems templates are not "whole-team". Are there other C++ features which impact code not directly using them, and are hence "whole-team"? I am especially interested in features not present in C. Update: I'm especially looking for features where there's no language-enforced sign you need to be aware of them. The first answer I got mentioned const-correctness, which is also whole-team, hence everybody needs to learn about it; however, AFAICS it will impact you only if you call a function which is marked const, and the compiler will prevent you from calling it on non-const objects, so you get something to google for. With exceptions, you don't even get that; moreover, they're always used as soon as you use new, hence exceptions are more "insidious". Since I can't phrase this as objectively, though, I will appreciate any whole-team feature. Appendix: Why this question is objective (if you wonder) C++ is a complex language, so many projects or coding guides try to select "simple" C++ features, and many people try to include or exclude some ones according to mostly subjective criteria. Questions about that get rightfully closed regularly here on SO. Above, instead, I defined (as precisely as possible) what a "whole-team" language feature is, provide an example (exceptions), together with extensive supporting evidence in the literature about C++, and ask for whole-team features in C++ beyond exceptions. Whether you should use "whole-team" features, or whether that's a relevant concept, might be subjective — but that only means the importance of this question is subjective, like always.

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• Building Enterprise Smartphone App &ndash; Part 3: Key Concerns

  - by Tim Murphy

  This is part 3 in a series of posts based on a talk I gave recently at the Chicago Information Technology Architects Group.  Feel free to leave feedback. Keys Concerns Of Smartphones In The Enterprise These are the factors that you need to be aware of and address in order to build successful enterprise smartphone applications.  Most of them have nothing to do with the application itself as you will see here. Managing Devices Managing devices is a factor that is going to effect how much your company will have to spend outside of developing the applications.  How will you track the devices within the corporation?  How often will you have to replace phones and as a consequence have to upgrade your applications to support new phones?  The devices can represent a significant investment of capital.  If these questions are not addressed you will find a number of hidden costs throughout the life of your solution. Purchase or BYOD We have seen the trend of Bring Your Own Device (BYOD) lately within the enterprise.  How many meetings have you been in where someone is on their personal iPad, iPhone, Android phone or Windows Phone?  The issue is if you can afford to support everyone's choice in device? That is a lot to take on even if you only support the current release of each platform. Do you go with the most popular device or do you pick a platform that best matches your current ecosystem and distribute company owned devices?  There is no easy answer here, but you should be able give some dollar value to both hardware and development costs related to platform coverage. Asset Tracking/Insurance Smartphones are devices that are easier to lose or have stolen than laptops and desktops. Not only do you have your normal asset management concerns but also assignment of financial responsibility. You also will need to insure them against damage and theft and add legal documents that spell out the responsibilities of the employees that use these devices. Personal vs. Corporate Data What happens when you terminate an employee?  How do you recover the device?  What happens when they have put personal data on the device?  These are all situation that can cause possible loss of corporate intellectual property or legal repercussions of reclaiming a device with personal data on it.  Policies need to be put in place that protect the company from being exposed to type of loss.  This can mean significant legal and procedural cost that you need to consider. Coming Up In the last installment of this series I will cover application development considerations. del.icio.us Tags: Smartphones,Enterprise Smartphone Apps,Architecture

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• How can I improve the battery life under 12.04 on my Inspiron 14z? [duplicate]

  - by cfogelberg

  This question already has an answer here: Tips to extend battery life for laptops and notebooks 24 answers How do I improve the battery life of my Inspiron 14z under Ubuntu 12.04? This laptop gets 4-5 hours of battery life using Windows (e.g. here). I've removed Windows, installed Ubuntu 12.04 and the initial battery life was only 2 hours. With some tweaks (described below) it's still only ~2.5 hours. For reference, the laptop is the latest model of the 14z: i5-3337U processor 32GB MSATA, 500GB HDD (5400rpm) AMD Radeon HD7570M graphics card I have put ext4 partitions on both the SSD and the HDD, and have mounted / to the SSD and /home to the HDD. I also put a 24gb linux swap partition at the start of the HDD, though I figure this won't be used all that much (the laptop has 8gb of RAM). After googling around and reading Ask Ubuntu and other sites extensively, I have done the following steps, and they have improved the battery life ~30 minutes (exact improvement not clear, but battery life is still nowhere near 4-5 hours). Installed Jupiter (and set Performance to "Power Saving") Installed laptop-mode-tools cat /proc/sys/vm/laptop_mode now outputs 5 (previously it output 0) But it's not clear that this will help: AskUbuntu question Turned down the brightness of my screen from full to 1/3 Other things I have heard about but have not tried for fear of frying the laptop or my linux install: Add "pcie_aspm=force" at the end of the line with "quiet splash" in /boot/grub/grub.cfg Enable ALPM, but it may already be enabled in 12.04? Enable i915 framebuffer compression Use a propietary driver for the graphics card? Turn off the graphics card? (what would happen if I relied on the internal Intel bridge?) Use TLP? Spin down the HDD more aggressively (howto, but I think laptop-mode-tools does this already) The only other thing I've noticed is that plastic just above the F5, F6 and F7 keys gets really hot. According to Jupiter my CPU temperature is only 69 celsius and the System Monitor shows CPU load at 7% so I don't think it's the CPU. Maybe it's the graphics card? Also, I've set up MongoDB and LAMP on the machine as well. When I run powertop MongoDB is high in the list, but I'm not sure if that's relevant to battery life because I'm not actually doing anything with MongoDB most of the time. Edit - Additional info as requested $ lspci -nnk | grep -iEA3 "(graphics|vga)" 00:02.0 VGA compatible controller [0300]: Intel Corporation Ivy Bridge Graphics Controller [8086:0166] (rev 09) Subsystem: Dell Device [1028:057f] Kernel driver in use: i915 Kernel modules: i915 -- 02:00.0 VGA compatible controller [0300]: Advanced Micro Devices [AMD] nee ATI Thames [Radeon 7500M/7600M Series] [1002:6841] Subsystem: Dell Device [1028:057f] Kernel driver in use: radeon Kernel modules: radeon

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• Ad-hoc reporting similar to Microstrategy/Pentaho - is OLAP really the only choice (is OLAP even sufficient)?

  - by TheBeefMightBeTough

  So I'm getting ready to develop an API in Java that will provide all dimensions, metrics, hierarchies, etc to a user such that they can pick and choose what they want (say, e.g., dimensions of Location (a store) and Weekly, and the metric Product Sales $), provide their choices to the api, and have it spit out an object that contains the answer to their question (the object would probably be a set of cells). I don't even believe there will be much drill up/down. The data warehouse the APIwill interface with is in a standard form (FACT tables, dimensions, star schema format). My question is, is an OLAP framework such as Mondrian the only way to achieve something akin to ad-hoc reporting? I can envisage a really large Cube (or VirtualCube) that contains most of the dimensions and metrics the user could ever want, which would give the illusion of ad-hoc reporting. The problem is that there is a ton of setup to do (so much XML) to get the framework to work with the data. Further it requires specific knowledge, such as MDX, and even moreso learning the framework peculiars (Mondrian API). Finally, I am not positive it will scale much better than simply making queries against a SQL database. OLAP to me feels like very old technology. Is performance really an issue anymore? The alternative I can think of would be dynamic SQL. If the existing tables in the data warehouse conform to a naming scheme (FACT_, DIM_, etc), or if a very simple config file/ database table containing config information existed that stored which tables are fact tables, which are dimensions, and what metrics are available, then couldn't the api read from that and assembly the appropriate sql query? Would this necessarily be harder than learning MDX, Mondrian (or another OLAP framework), and creating all the cubes? In general, I feel that OLAP is at the same time too powerful (supports drill up/down, complex functions) and outdated and am reluctant to base my architecture on it. However, I am unsure if the alternative(s), such as rolling my own ad-hoc reporting framework using dynamic SQL would remove any complexity while still fulfilling requirements, both functional and non-functional (e.g., scalability; some FACT tables have many millions of rows). I also wonder about other techniques (e.g., hive). Has anyone here tried to do ad-hoc reporting? Any advice? I expect this project to take a pretty long time (3 months min, but probably longer), so I just do not want to commit to an architecture without being absolutely sure of its pros and cons. Thanks so much.

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• EF Doesn't Like Same Named Tables

  - by Anthony Trudeau

  Originally posted on: http://geekswithblogs.net/tonyt/archive/2013/07/02/153327.aspxIt's another week and another restriction imposed by the Entity Framework (EF). Don't get me wrong. I like EF, but I don't like how it restricts you in different ways. At this point you may be asking yourself the question: how can you have more than one table with the same name?The answer is to have tables in different schemas. I do this to partition the data based on the area of concern. It allows security to be assigned conveniently. A lot of people don't use schemas. I love them. But this article isn't about schemas.In the situation I have two tables:Contact.PersonEmployee.PersonThe first contains the basic, more public information such as the name. The second contains mostly HR specific information. I then mapped these tables to two classes. I stuck to a Table per Class (TPC) mapping, because of problems I've had in the past implementing inheritance with EF. The following code gives you the basic contents of the classes.[Table("Person", Schema = "Employee")]public class Employee {   ...   public int PersonId { get; set; }   [ForeignKey("PersonId")]   public virtual Person Person { get; set; }}[Table("Person", Schema = "Contact")]public class Person {   [Key]   public int Id { get; set; }   ...}This seemingly simple scenario just doesn't work. The problem occurs when you try to add a Person to the DbContext. You get an InvalidOperationException with the following text:The entity types 'Employee' and 'Person' cannot share table 'People' because they are not in the same type hierarchy or do not have a valid one to one foreign key relationship with matching primary keys between them..This is interesting for a couple of reasons. First, there is no People table in my database. Second, I have used the SetInitializer method to stop a database from being created, so it shouldn't be thinking about new tables.The solution to my problem was to change the name of my Employee.Person table. I decided to name it Employee.Employee. It's not ideal, but it gets me past the EF limitation. I hope that this article will help someone else that has the same problem.

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• High traffic chat - how to check if there is new message and show it for all users

  - by user2633999

  I already had question about this but obviously it was not accepted very well, apparently too long when it's actually more information so you could have given me better answer. Ok, I will be much clearer now. Best possible logic to develop scalable chat in terms of stability, storing/reading messages on chat, updating chat on new message for all users etc.? I have most of this developed, the logic I think I miss is -- check if there is new message and show it for all users. I have this implemented but it crashes the site due to its traffic of 300k-400k people, so that's my main question. The chat is PHP based and uses Pusher (www.pusher.com) for instant messaging but it lacks what I need because it's more like a websocket. I'm using hardcoded files to keep messages (want to avoid database as much as possible). It's a no extension type of file, I'm sure you know. I'm getting crash with $fp = fopen(..., "w"); // pretend ... is the path and filename fwrite($fp, $msg); //hardcode the message fclose($fp); where $msg is the message itself. I'm having 1 file per message. I show last 150 messages = 150 file accesses and reads, yeah it's too much I guess. I have better logic now which I'm pursuing and that is 1 file with last 50-100 messages at all time. Sure it should be much better. How does it crash, that's the trickiest part because everything seems ordinary, believe me it is difficult to determine what exactly crashes the site, but in like 5 minutes when I try to open the site it's gone, then I put the old content without chat and is back online again. I'm having jquery post every 1 second to check if there is new message. I'm using timestamp in a special file where I keep the time last message was sent and if ((time() - time in file) <= 2) = reload last 150 messages including the last one. Too much input/output, write/read or however to say it I think is what crashes the site.

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• What's a good way to get an IT internship? [closed]

  - by user1419715

  I'm a second year CS student who's worked really hard to build and expand my skills. I've spent the past week now trying to find a place to volunteer (i.e. work for FREE) so I can get a little bit of in-the-door experience with web development. I have a portfolio with several decent projects, a handful of languages and other hard/soft skills that employers constantly say they're clamoring for. I can't even get people to take my calls. This is me offering to work for them for FREE, remember. I'm in a reputable program at a respected school, get decent grades and...yeah, I've worked really hard to be presentable. On the rare occassions I actually get to speak to somebody at a design firm they hedge and do everything they can to get me off the phone. Nobody's ever expressed even the slightest interest in taking me on. The answer to the experience problem is supposed to be "you need to spend a year or two building up a big portfolio of projects on your own" so that employers will be impressed. I've done that. Websites, standalone apps, etc.. Nobody will even look at my resume, though. Question: Why does there seem to be so little interest in taking on upaid interns in the world of IT? Update: Sorry you all think I'm too aggressive or angry. It wasn't my intent to be a jerk to people while asking them for their opinions. That said, how would you feel if employer after employer turned you down cold when you offered yourself to them without asking for remuneration? One can't even get an unpaid job in this economy now, it seems. How am I going about my search? I find web firms in my area and contact them via email with a brief sales pitch of myself and a resume attached. Then a couple of days later I follow up with a phone contact. Nobody--anywhere--is advertising for interns of any kind. If there were I'm sure there'd be about 500 resumes per position, even unpaid. I've had good experiences in the past with cold-calling firms for actual paid jobs in other industries (hiring is a pain in the ass process and a call like this can show initiative while reducing a busy employer's need to do all the hiring overhead work), so I thought volunteering would work at least as well. My skills are pretty good for a CS student and include the usual suspects: HTML/CSS/Javascript, Python, Java, C, C#/.Net etc etc. I made a point on my resume to tie each ability claim to a project as well. Oh, and regarding the "working for free still costs the employer money" argument: that's an excellent point I hadn't though of. But it means...what? I have to pay the employer for the privilege of working there now?

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• git commit –m “CodePlex now supports Git!”

  Finally, yes, CodePlex now supports Git! Git has been one of the top rated requests from the CodePlex community for some time: Admittedly, when we launched CodePlex, we never expected that at some point we would be running a source control system originally invented by Linus Torvalds to use for the Linux kernel. Though I would also say, nobody would have thought the open source ecosystem would be as important to Microsoft as it has become now. Giving CodePlex users what they ask for and supporting their open source efforts has always been important to us, and we have a long list of improvements planned, so stay tuned as we have more up our sleeves! Why Git? So why Git? CodePlex already has Mercurial for distributed version control and TFS (which also supports subversion clients) for centralized version control. The short answer is that the CodePlex community voted, loud and clear, that Git support was critical. Additionally, we just like it, we use Git on our team every day and making the DVCS workflows more available to the CodePlex community is just the right thing to do. Forks and Pull Requests One of the capabilities that distributed version control systems, such as Mercurial and Git, enable is the Fork and Pull Request workflow.  Just like with Mercurial, projects configured to use Git enable Forking the source and submitting contributions back via Pull Requests. The Fork/Pull Request workflow is a key accelerator to many open source projects and you will see improvements in our support coming later this year. More Choice With the addition of Git, now CodePlex has three options when it comes to Open Source project hosting. Projects can now select between TFS, Mercurial, and Git. Each developer has their own preferences, and for some, centralized version control makes more sense to them. For others, DVCS is the only way to go. We’re equally committed to supporting both these technologies for our users. You can get started today by creating a new project or contribute to an existing project by creating a fork. For help on getting started with Git on CodePlex, see our help documentation here. If you would like to switch your project to use Git, please contact us at CodePlex Support with your project information, and we will be happy to help you out. We're Listening CodePlex is your community, and we want to deliver the experiences you need to have a successful open source project. We want your ideas and feedback to make CodePlex a great development community.  The issue tracker on CodePlex is publicly available. Add suggestions or vote up existing suggestions. And you can always find us on Twitter, I’m @mgroves84; follow us to keep up to date with our latest releases: @codeplex

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• Are there software options (preferabbly .NET) for doing distance and speed analysis of footballers moving on video?

  - by Anonymous Type

  Editing Question for Clarity Thanks for feedback so far, very insightful. I'm not sure how far along this part of the software community is, and what if any libraries exist for me to leverage from. Heres what I'm trying to do. Problem: Take an existing video of a game of rugby league. The Rugby League field is 100 metres long, 70 metres wide, and has white line markings every 10 metres running along the width of the field, as well as along the sidelines. Each side has 13 players on the field. Players on each team have identical jerseys that normally constrast strongly against background colours (green/brown field colour) and the referee's colour (usually yellow) and the designated water runner (orange). All players have a unique number in thick white lettering on their backs for identification. Video is taken with a high definition camera. Currently only one camera is used (2D) and existing video does not contain a foreground object of fixed spatial dimensions (as suggested in one answer for comparision measurements, however I could add this to future filming sessions if it is worthwhile). The player's do not run in a straight line 50% of the time but will go sideways on on a diagonal to the play the ball. The distance measured always starts from the spot of the previous "tackle", which ends where the player stops forward movement. It is not always possible to determine the players number from the video (facing other direction, sunlight, others standing in the way of the camera). But this isn't important as the software could allow for manual inputting of unknown "runs" at a later point after analysis. Determine the distance between two points (i.e. where the player started his "run" and where he finished it). I'm guessing that this would be quite doable if I manually marked the start and end point in the video. But how would I use landmarks in the background to determine the distance (assuming the person taking the video has kept it from jerking around). Question: Do software packages or libraries exist that are specialised enough to assist with writing analysis software to determine a sports persons distance travelled based on video taken of the performance?

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• PHP or C++? I just want to choose a language and focus on it!

  - by user19177

  I love C++, but I feel I don't know if I should focus on web, so PHP, or C++. It's just an hard choice because right now I want to focus on one language and don't want to switch it a few months later. With C++ I'd program in SDL, while with PHP I don't know yet. I am not a very advanced programmer but I know basics of programming and can get going very well if determined. The problem is I just don't know.. I'm like OK! I'll go for C++! Then a minute later, wait what if I went with C#? Why this that.. ! I've read milion threads about C vs VB C# Python Ruby etc, all of them which I could find! It got me nowhere. The problem is probably I need to know something from some experts I guess.. I'm sure I'm not the only one who feels/felt like I do right now yeah? Uhm... I guess I might help you with some details so your answer may be easier to write! ( And also, if you want to say something else which is not related to PHP or C++, you can do that, I've just got to the conclusion that C++ and PHP are the ones that are worth it but yeah. C# I've discarded due to some stuff I read which says in future the projects I'd start now could just be useless and stuff like that.. ) Ok well : I'm 18 years old, and I program as hobby right now, but I do hope to go to a programming college in future. ( That would be in 2 years ). Hmm, I like programming games, and I'm mostly bothered by the fact "this language could be useless to what I need to do" ( I don't know how to explain this feeling! ) I don't know which other details I could add... I hope you guys can help me choose my path, this is really stressing me I'm wasting my time not doing anything right now because I don't know which language to use..! Thanks!

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• IndexOutOfRangeException on World.Step after enabling/disabling a Farseer physics body?

  - by WilHall

  Earlier, I posted a question asking how to swap fixtures on the fly in a 2D side-scroller using Farseer Physics Engine. The ultimate goal being that the player's physical body changes when the player is in different states (I.e. standing, walking, jumping, etc). After reading this answer, I changed my approach to the following: Create a physical body for each state when the player is loaded Save those bodies and their corresponding states in parallel lists Swap those physical bodies out when the player state changes (which causes an exception, see below) The following is my function to change states and swap physical bodies: new protected void SetState(object nState) { //If mBody == null, the player is being loaded for the first time if (mBody == null) { mBody = mBodies[mStates.IndexOf(nState)]; mBody.Enabled = true; } else { //Get the body for the given state Body nBody = mBodies[mStates.IndexOf(nState)]; //Enable the new body nBody.Enabled = true; //Disable the current body mBody.Enabled = false; //Copy the current body's attributes to the new one nBody.SetTransform(mBody.Position, mBody.Rotation); nBody.LinearVelocity = mBody.LinearVelocity; nBody.AngularVelocity = mBody.AngularVelocity; mBody = nBody; } base.SetState(nState); } Using the above method causes an IndexOutOfRangeException when calling World.Step: mWorld.Step(Math.Min((float)nGameTime.ElapsedGameTime.TotalSeconds, (1f / 30f))); I found that the problem is related to changing the .Enabled setting on a body. I tried the above function without setting .Enabled, and there was no error thrown. Turning on the debug views, I saw that the bodies were updating positions/rotations/etc properly when the state was changes, but since they were all enabled, they were just colliding wildly with each other. Does Enabling/Disabling a body remove it from the world's body list, which then causes the error because the list is shorter than expected? Update: For such a straightforward issue, I feel this question has not received enough attention. Has anyone else experienced this? Would anyone try a quick test case? I know this issue can be sidestepped - I.e. by not disabling a body during the simulation - but it seems strange that this issue would exist in the first place, especially when I see no mention of it in the documentation for farseer or box2d. I can't find any cases of the issue online where things are more or less kosher, like in my case. Any leads on this would be helpful.

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• Is it smart to take a year off from school to get experience?

  - by user134147

  firstly I apologize if this question is not appropriate for the site, but I've seen other similar (though slightly deviant) questions on this sight before and I know the people here are the most qualified to answer my question. Anyways, I'm currently between my sophomore and junior years at a 4 year university, and after a bit of deliberation I've decided on computer science as a major (BA, by the way, as a BS would require me to stay at least an extra year the way our program is set up). I've been interested now in programming for a few months and I've developed a passion for it in a very short time. I began learning C++, migrating to Java recently when I learned my school focuses on this language. Now, I should mention that the concept of higher education has never sat well with me, so part of my motivation for wanting to take time off is to truly challenge myself and see what I can accomplish when I actually try at something. The autodidact in me finds it difficult to focus on my passions while trying to keep a high GPA in unrelated classes. However, I understand the times we live in and therefore would plan to complete my degree after this year. So my question is whether or not the skills I learn in a year off from college could justify the time off from school. Unfortunately, I don't believe I know enough yet to gain any professional experience (internship, etc.) so I would mostly focus my time on learning Java and another language, possibly Wordpress (to gain an understanding of web programming concepts as I have not yet decided what field I want to get into, and to make some money to fund my off-year), and to delve into security concepts, which also interest me. I'm hoping I could work on projects, such as simple applications or contributions to open source software during this time to enhance my resume once I do finish school, so I can find a job out of college easier. I do not want to be the new hire who knows nothing beyond the concepts of his Java textbooks. Does anyone have any input about these thoughts of mine, or any ideas for where I should focus my studies or how high I might set the bar for my work? Thanks a lot everyone!

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• What is the right way to group this project into classes?

  - by sigil

  I originally asked this on SO, where it was closed and recommended that I ask it here instead. I'm trying to figure out how to group all the functions necessary for my project into classes. The goal of the project is to execute the following process: Get the user's FTP credentials (username & password). Check to make sure the credentials establish a valid connection to the FTP server. Query several Sharepoint lists and join the results of those queries to create a list of items that need to have action taken on them. Each item in the list has a folder. For each item: Zip the contents of the folder. Upload the folder to the FTP server using SFTP Update the item's Sharepoint data. Email the user an Excel report showing, e.g., Items without folder paths Items that failed to zip or upload Steps 2-5 are performed on a periodic basis; if step 2 returns an invalid connection, the user is alerted and the process returns to step 1. If at any point the user presses a certain key, the process terminates. I've defined the following set of classes, each of which is in its own .cs file: SFTP: file transfer processes DataHandler: Sharepoint data retrieval/querying/updating processes. Also makes and uploads the zip files. Exceptions: Not just one class, this is the .cs file where I have all of my exception classes. Report: Builds and sends the report. Program: The main class for running the program. I recognize that the DataHandler class is a god object, but I don't have a good idea of how to refactor it. I feel like it should be more fine-grained than just breaking it into Sharepoint, Zip, and Upload, but maybe that's it. Also, I haven't yet worked out how to combine the periodic behavior with the "wait for user input at any point in the process" part; I think that involves threads, which means other classes to manage the threads... I'm not that well-versed in design patterns, but is there one that fits this project well? If this is too big of a topic to neatly explain in an SO answer, I'll also accept a link to a good tutorial on what I'm trying to do here.

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• Ubuntu 11.04 is not opening

  - by Fortunate

  I am using Ubuntu 11.04 with Windows 7. Ubuntu was working nice but now when I choose Ubuntu 11.04 from boot loader, it is not opening. Just Purple screen is coming but then nothing change. I can't see login menu, it doesn't pass to the login menu. What should I do? Has anyone this problem? Thanks for your answer. I did the steps you wrote Frantique. But now I have a black screen and then nothing. When I choosed ubuntu 11.04 from bootloader, first purple screen is opening then after 1 second it is going to a black screen. And I have nothing again. I can't write anything. Just I have a black screen. It is not openining. Before those problems they work together nice. There aren't any errors. Lets I tell you what did I change: I installed docky, and theme of MACOSX. They were working nicely. And I tried to install a nice calendar. To do this installation I changed a litle bit the file sources.list. That calendar program was working succcesfully too, after installation. The theme MACOSX was working succesfully there weren't any problem. After some days maybe meeks I had that problem which I asked in the above. Now when I tried to update I have a lots of errors. Like: Failed to urls... can't access archive something... .... Failed to urls... can't access archive something... .... ..... Failed to urls... can't access archive something... I hope you will solve the problem. I want my MacOSXUbuntu back :)

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• Visual Studio 2010/2012 Context Menus and a Keyboard

  - by SergeyPopov

  As a software developer, I spend a lot of time using Visual Studio. I have to say that I completely satisfied with Visual Studio generally. Nevertheless, sometimes Visual Studio starts annoying me. One issue which poisoned my existence for a long time is that context menu behavior in VS2010 is a little different than it was in VS2005/2008. Unfortunately, in VS2012 this behavior remains the same as in VS2010. So, what is the issue? Working with Visual Studio, I use the keyboard in most cases. I also use the Apps key on the keyboard to open context menus in the code editor. Moreover, long time ago I am got used to using some key sequences, and press the keys without even thinking. In VS2008, a mouse pointer position didn’t affect context menu navigation if I used the keyboard. Every time I opened a context menu I was sure that, for example, the "Apps, Down, Down, Enter, Up, Enter" key sequence always invoke "Organize Usings > Remove and Sort" function. But in VS2010, this behavior has been changed. If a mouse pointer is located over an opened context menu, the menu item under the mouse pointer becomes selected immediately! So, now the "Apps, Down, Down, Enter, Up, Enter" key sequence will not lead to expected results all the time. In some cases, the result may be a little scary. If you are using Visual SVN extension, this key sequence may invoke "Revert whole file" function. Of course, this is not a fatal problem because "Undo" function restores all the changes, but this behavior strongly annoys me. In Visual Studio 2012, context menu behavior is a little different than in VS2010, but a mouse pointer position still affects the keyboard navigation in the context menu, and this behavior is still annoying. I tried to find the way how to change this behavior, but I didn’t manage to find the answer quickly. Then I decided to go right though, so I wrote a small utility which fixes this issue. This utility watches for Apps key, and if the key is pressed in Visual Studio, the utility moves the mouse pointer to the top of the screen before opening the context menu. You can find binaries and the source code of this utility here: http://code.google.com/p/vs-ctx-menu-fix/downloads/list This utility works fine in Windows 7 and Windows 8 x64. I wrote the first version in January, 2011; now I just added Visual Studio 2012 support. I hope you will find this utility useful! :)

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• XNA 4.0: 2D Camera Y and X are going in wrong direction

  - by Setheron

  I asked this question on stackoverflow but assumed this might be a better area to ask it as well for a more informed answer. My problem is that I am trying to create a camera class and have it so that my camera follows the proper RHS, however the Y axis seems to be inverted since on the screen the 0 starts at the top. Here is my Camera2D Class: class Camera2D { private Vector2 _position; private float _zoom; private float _rotation; private float _cameraSpeed; private Viewport _viewport; private Matrix _viewMatrix; private Matrix _viewMatrixIverse; public static float MinZoom = float.Epsilon; public static float MaxZoom = float.MaxValue; public Camera2D(Viewport viewport) { _viewMatrix = Matrix.Identity; _viewport = viewport; _cameraSpeed = 4.0f; _zoom = 1.0f; _rotation = 0.0f; _position = Vector2.Zero; } public void Move(Vector2 amount) { _position += amount; } public void Zoom(float amount) { _zoom += amount; _zoom = MathHelper.Clamp(_zoom, MaxZoom, MinZoom); UpdateViewTransform(); } public Vector2 Position { get { return _position; } set { _position = value; UpdateViewTransform(); } } public Matrix ViewMatrix { get { return _viewMatrix; } } private void UpdateViewTransform() { Matrix proj = Matrix.CreateTranslation(new Vector3(_viewport.Width * 0.5f, _viewport.Height * 0.5f, 0)) * Matrix.CreateScale(new Vector3(1f, 1f, 1f)); _viewMatrix = Matrix.CreateRotationZ(_rotation) * Matrix.CreateScale(new Vector3(_zoom, _zoom, 1.0f)) * Matrix.CreateTranslation(_position.X, _position.Y, 0.0f); _viewMatrix = proj * _viewMatrix; } } I test it using SpriteBatch in the following way: protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); Vector2 position = new Vector2(0, 0); // TODO: Add your drawing code here spriteBatch.Begin(SpriteSortMode.Immediate, BlendState.AlphaBlend, null, null, null, null, camera.ViewMatrix); Texture2D circle = CreateCircle(100); spriteBatch.Draw(circle, position, Color.Red); spriteBatch.End(); base.Draw(gameTime); }

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