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• Sql Server differential backup : Simple vs Full recovery model

  - by MaxiWheat

  I need to better understand the backup process under SQL Server 2008. Since drive space is a kind of matter for us and we want to have a better disaster recovery solution, I decided that we will implement differential backups throughout the day (every hour). Am I right to think that if I keep the recovery model of my databases to Simple, the differential backup will be almost the same size as Full Backup (too big to make one every hour) ? I already tried to switch to Full recovery and it seemed to have fixed the issue (differential backups were way smaller). I heard that the recovery model must be set to Full to use Log backups (to the minute recovery etc., but we don't need that) but never about differential backups. So, is the recovery model really having an impact on differential backups or am I missing something ? Thank you

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• Version control and branching when using Oracle

  - by Ed Woodcock

  Hi folks: At work we're using Oracle and C#/ASP.net to handle a customer's website, this site is very large-scale so the database is very large. We use Perforce for our version control, and tack create or replace scripts to FogBugz cases whenever a database change, which has been fine until now, as we are now at a point where five developers are working on five expansions for the system, each on a seperate Perforce branch. Unfortunately, we cannot get duplicate databases, due to the database size, so everyone is still working from the same one. This is obviously a cause of problems: only ten minutes ago we had a bit of an issue where a stored procedure change for a branch propagated over to the Pre-Production server and caused a large number of crashes for the testers. Ideally, we would like a way to track these changes without having to manually keep track of them through FogBugz. My question is: how do you lot handle this situation? I'm sure there must be a good way by now to handle versioning, or at least tracking changes, in an Oracle database.

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• Am I misunderstanding chown and chmod?

  - by isomorphismes

  I want to either extend the size of my guest partition or figure out how to copy stuff from the guest partition to my normal /home directory. (Because of some other problems I can only run Xorg as guest, but I can log into virtual console as myself or root.) Here's the motivation: I want to torrent a large file. It's larger than my guest filesystem. But I have plenty of space on my real drive, I just can't log into it graphically. So I tried to set up a "pipe" to get the file out of the tmpfs. I did: su -u myself #catch mkdir ~/receiver_dir sudo su cd /tmp/guest-lkj567UIO/ #throw ln -s mario_pipe /home/myself/receiver_dir chown -R guest-lkj567UIO /home/myself/receiver_dir chown -R guest-lkj567UIO /tmp/guest-lkj567UIO/mario_pipe chmod -R a+rw /home/myself/receiver_dir chmod -R a+rw /tmp/guest-lkj567UIO/mario_pipe su -u guest-lkj567UIO cd /tmp/guest-lkj567UIO cd mario_pipe touch something #success! However, when I try to torrent to /tmp/guest-lkj567UIO/mario_pipe, Transmission says I don't have write permissions. But it looks like I just wrote there? And that everybody (a+rw) can write there in fact? Maybe this indicates I don't actually understand chown and chmod but nothing from their man pages pops out.

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• How do I prevent other dynamic bodies from affecting the player's velocity with Box2D?

  - by Milo

  I'm working on my player object for my game. PhysicsBodyDef def; def.fixedRotation = true; def.density = 1.0f; def.position = Vec2(200.0f, 200.0f); def.isDynamic = true; def.size = Vec2(50.0f,200.0f); m_player.init(def,&m_physicsEngine.getWorld()); This is how he moves: b2Vec2 vel = getBody()->GetLinearVelocity(); float desiredVel = 0; if (m_keys[ALLEGRO_KEY_A] || m_keys[ALLEGRO_KEY_LEFT]) { desiredVel = -5; } else if (m_keys[ALLEGRO_KEY_D] || m_keys[ALLEGRO_KEY_RIGHT]) { desiredVel = 5; } else { desiredVel = 0; } float velChange = desiredVel - vel.x; float impulse = getBody()->GetMass() * velChange; //disregard time factor getBody()->ApplyLinearImpulse( b2Vec2(impulse,0), getBody()->GetWorldCenter(),true); This creates a few problems. First, to move the player at a constant speed he must be given a high velocity. The problem with this is if he just comes in contact with a small box, he makes it move a lot. Now, I can fix this by lowering his density, but then comes my main issue: I need other objects to be able to run into him, but when they do, he should be like a static wall and not move. I'm not sure how to do that without high density. I cannot use collision groups since I still need him to be solid toward other dynamic things. How can this be done? Essentially, how do I prevent other dynamic bodies from affecting the player's velocity?

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• Transfer files using ssh

  - by zozo

  Good day to all. I am using ssh (winSCP) to transfer some files from a server to my workstation. The problem is that at some files I get disconnected. Always same files. I am the owner of the directory so I guess the file permissions is not a problem. (Also I set the permissions to 777). Is there a size limit or something like that? Thank you for your time. Protocol is SFTP, server is 32bit machine. Files are 100MB tops. Added: Worked with filezilla using ftp. This temporarily fix the problem but is not exactly a solution since maybe next time I won't have root access to create a ftp account

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• Cost effective way to provide static media content

  - by james

  I'd like to be able to deliver around 50MB of static content, either in about 30 individual files up to 10MB or grouped into 3 compressed files, around 5k to 20k times a day. Ideally I'd like to put some sort of very basic security around providing the data to ensure that a request is from the expected source, but if tossing the security for a big reduction in price is possible then it's an option. Does anyone have any suggestions other than what I've found: Google AppEngine is $0.12/GB & I believe has a file size limit of 10MB so I'd have to break the data up a bit. So a rough calculation would seem to be that this would cost me about $30 to $120 a day. Or I've seen something like what seems to be just public static content delivery with no type of logic capabilities like Usenet.nl at what I think calculates to about $0.025/GB which would cost me about $6 to $25 a day. Any idea if I'm going about these calculations right & if there might be a better option for just static content on a decently high volume delivery? Again some basic security would be great but if cost is greatly reduced without it then I'm up for that.

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• Flickering when accessing texture by offset

  - by TravisG

  I have this simple compute shader that basically just takes the input from one image and writes it to another. Both images are 128/128/128 in size and glDispatchCompute is called with (128/8,128/8,128/8). The source images are cleared to 0 before this compute shader is executed, so no undefined values should be floating around in there. (I have the appropriate memory barrier on the C++ side set before the 3D texture is accessed). This version works fine: #version 430 layout (location = 0, rgba16f) uniform image3D ping; layout (location = 1, rgba16f) uniform image3D pong; layout (local_size_x = 8, local_size_y = 8, local_size_z = 8) in; void main() { ivec3 sampleCoord = gl_GlobalInvocationID.xyz; imageStore(pong, imageLoad(ping,sampleCoord)); } Reading values from pong shows that it's just a copy, as intended. However, when I load data from ping with an offset: #version 430 layout (location = 0, rgba16f) uniform image3D ping; layout (location = 1, rgba16f) uniform image3D pong; layout (local_size_x = 8, local_size_y = 8, local_size_z = 8) in; void main() { ivec3 sampleCoord = gl_GlobalInvocationID.xyz; imageStore(pong, imageLoad(ping,sampleCoord+ivec3(1,0,0))); } The data that is written to pong seems to depend on the order of execution of the threads within the work groups, which makes no sense to me. When reading from the pong texture, visible flickering occurs in some spots on the texture. What am I doing wrong here?

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• How do I get meaningful error messages in IIS7?

  - by Petras

  I have a classic ASP website that is crashing in IIS7. It is crashing because IIS doesn't allow file uploads greater than a certain size. I know this because files below about 200k work fine. I removed the Status Code 500 error in IIS but I still don't get a file name and the line where my code failed as I do when running locally. Instead I get: "The page cannot be displayed because an internal server error has occurred. If you are the system administrator please click here to find out more about this error." How do I get a file name and the line where my code failed? Here are my IIS settings:

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• Caching DNS server (bind9.2) CPU usage is so so so high.

  - by Gk

  Hi, I have a caching-only dns server which get ~3k queries per second. Here is specs: Xeon dual-core 2,8GHz 4GB of RAM Centos 5x (kernel 2.6.18-164.15.1.el5PAE) bind 9.4.2 rndc status: recursive clients: 666/4900/5000 About 300 new queries (not in cache) per second. Bind always uses 100% on one core on single-thread config. After I recompiled it to multi-thread, it uses nearly 200% on two core :( No iowait, only sys and user. I searched around but didn't see any info about how bind use CPU. Why does it become bottleneck? One more thing, here is RAM usage: cat /proc/meminfo MemTotal: 4147876 kB MemFree: 1863972 kB Buffers: 143632 kB Cached: 372792 kB SwapCached: 0 kB Active: 1916804 kB Inactive: 276056 kB I've set max-cache-size to 0 to make sure bind can use as much RAM as it want, but it always stop at ~2GB. Since every second we got not cached queries so theoretically RAM must be exhausted but it wasn't. Do you have any idea? TIA, -Gk

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• Incremental backup up from a remote ftp box to a Windows server

  - by user65712

  I need to backup a website to a Windows server every week and I only have access to remote FTP. I'd like to use an incremental backup program so that I can just copy the files every week on a schedule and not worry too much about the size of the backups becoming an issue. Unfortunately, I can't find a Windows program that will automatically make incremental backups of specific FTP folders and files, as most programs are designed to backup to FTP, not from it. Are there any applications that can do this? I also have a Ubuntu 10.04 box I could use to relay the site to the Windows server if I needed to run Linux programs, but I would prefer a Windows-only solution over a Linux/Windows one, and a combined Linux/Windows solution over not having it work at all.

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• MiniMax not working properly(for checkers game)

  - by engineer

  I am creating a checkers game but My miniMax is not functioning properly,it is always switching between two positions for its move(index 20 and 17).Here is my code: public double MiniMax(int[] board, int depth, int turn, int red_best, int black_best) { int source; int dest; double MAX_SCORE=-INFINITY,newScore; int MAX_DEPTH=3; int[] newBoard=new int[32]; generateMoves(board,turn); System.arraycopy(board, 0, newBoard, 0, 32); if(depth==MAX_DEPTH) { return Evaluation(turn,board);} for(int z=0;z<possibleMoves.size();z+=2){ source=Integer.parseInt(possibleMoves.elementAt(z).toString()); System.out.println("SOURCE= "+source); dest=Integer.parseInt(possibleMoves.elementAt(z+1).toString());//(int[])possibleMoves.elementAt(z+1); System.out.println("DEST = "+dest); applyMove(newBoard,source,dest); newScore=MiniMax(newBoard,depth+1,opponent(turn),red_best, black_best); if(newScore>MAX_SCORE) {MAX_SCORE=newScore;maxSource=source; maxDest=dest;}//maxSource and maxDest will be used to perform the move. if (MAX_SCORE > black_best) { if (MAX_SCORE >= red_best) break; /* alpha_beta cutoff */ else black_best = (int) MAX_SCORE; //the_score } if (MAX_SCORE < red_best) { if (MAX_SCORE<= black_best) break; /* alpha_beta cutoff */ else red_best = (int) MAX_SCORE; //the_score } }//for ends return MAX_SCORE; } //end minimax I am unable to find out the logical mistake. Any idea what's going wrong?

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• How to mange big amount users at server side?

  - by Rami

  I built a social android application in which users can see other users around them by gps location. at the beginning thing went well as i had low number of users, But now that I have increasing number of users (about 1500 +100 every day) I revealed a major problem in my design. In my Google App Engine servlet I have static HashMap that holding all the users profiles objects, currenty 1500 and this number will increase as more users register. Why I'm doing it Every user that requesting for the users around him compares his gps with other users and check if they are in his 10km radius, this happens every 5 min on average. That is why I can't get the users from db every time because GAE read/write operation quota will tare me apart. The problem with this desgin is As the number of users increased the Hashmap turns to null every 4-6 hours, I thing that this time is getting shorten but I'm not sure. I'm fixing this by reloading the users from the db every time I detect that it became null, But this causes DOS to my users for 30 sec, So I'm looking for better solution. I'm guessing that it happens because the size of the hashmap, Am I right? I have been advised to use spatial database, but that mean that I can't work with GAE any more and that mean that I need to build my big server all over again and lose my existing DB. Is there something I can do with the existing tools? Thanks.

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• Worst SysAdmin Accident

  - by Ward

  In line with the question about Best sysadmin accident, what's the worst accident you've been involved in? Unlike the previous question, I mean "worst" in the sense of most system damage or actual harm to people. I'll start with mine: We have two remote wiring closets that are at the end of a 100-foot corridor which has a metal grate for the floor. After we had Cat6 cable installed, the contractors cleaned up all the debris that dropped through the grating to the concrete 3 feet below. A co-worker and I entered the corridor to check on the progress one day but were distracted and didn't notice that a piece of grating had been moved aside. My buddy stepped into air and his chest slammed into the steel crossbar. He was winded and sore enough to take a couple days off, but luckily the steel beam had rounded edges and the size of the opening was such that he didn't smack his head into it or the floor below. Obviously we learned that areas where the floor is partially removed need to be flagged.

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• Microsoft Outlook 2007 Plain Text/HTML message behaviour?

  - by goldenmean

  I use MS Outlook as email client. When I receive email from certain email addresses(sender within my company/domain itself), and I use the reply button option to reply it, all the menus like - Font type, Font size, Text color, Bold, Italics, Text indentation, Bullets, numbering, are disabled. It doesn't allow me to use any of the above features. This happens only for some email id's where I receive mail from. Not all. Then when I checked in the message properties, it was Plain Text , rather than HTML. But shouldn't outlook allow me the formatting of the messages I reply/compose based on My settings which are HTML? How can I enable to have Rich text formatting enabled while I reply to a text mail?

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• JVM memory initializazion error after windows update

  - by gianni

  We have three Windows Server 2003 with 2 GB RAM. Server1 tomcat 5.5.25 jvm version SUN 1.6.0_11-b03 Server2 tomcat 5.5.25 jvm version SUN 1.6.0_14-b08 Server3 tomcat 6.0.18 jvm version SUN 1.6.0_14-b08 For the three servers JVM parameters are: -XX:MaxPermSize=256m -Dcatalina.base=C:\Programmi\Apache Group\apache-tomcat-5.5.25 -Dcatalina.home=C:\Programmi\Apache Group\apache-tomcat-5.5.25 -Djava.endorsed.dirs=C:\Programmi\Apache Group\apache-tomcat-5.5.25\common\endorsed -Djava.io.tmpdir=C:\Programmi\Apache Group\apache-tomcat-5.5.25\temp vfprintf -Xms512m -Xmx1024m For some months everithing worked fine. Last friday we installed some windows updates. After the reboot tomcat doesnt start with error: Error occurred during initialization of VM Could not reserve enough space for object heap We reduced the parameter -Xmx1024m to -Xmx768m and now tomcat starts. But we need greater max heap size What happened to our servers ? Thanks in advance.

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• Why are my videos playing speeded up with no audio, but work fine if I log in as a guest?

  - by Martins Kruze

  Since the start of this week I have been experiencing a glitch in the multimedia on my Samsung R518 laptop. I have 2 problems: Videos in every player are speeded up around 2 or 4 times (including youtube.com (both HTML5 and flash variants), any other video on the web and videos on my laptop played by Totem Media Player), exception is VLC player, but 2nd problem does concern even that. There is no sound - simple as that (with or without headphones plugged in). These all problems are now, and has not seen before, I upgraded to Ubuntu 10.10 after it was possible, and from start I didn't have anything from this - it just started in this week. I haven't even putted new software in. I have more or less solved the question (kind of) - I just logged in as a guest - and it all works, but when I make a new user - it does not. Please help me. Some stats below: sudo lshw -c sound *-multimedia description: Audio device product: RV710/730 vendor: ATI Technologies Inc physical id: 0.1 bus info: pci@0000:01:00.1 version: 00 width: 32 bits clock: 33MHz capabilities: pm pciexpress msi bus_master cap_list configuration: driver=HDA Intel latency=0 resources: irq:48 memory:cfeec000-cfeeffff *-multimedia description: Audio device product: 82801I (ICH9 Family) HD Audio Controller vendor: Intel Corporation physical id: 1b bus info: pci@0000:00:1b.0 version: 03 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list configuration: driver=HDA Intel latency=0 resources: irq:47 memory:fc200000-fc203fff sudo lshw -c video *-display description: VGA compatible controller product: M92 LP [Mobility Radeon HD 4300 Series] vendor: ATI Technologies Inc physical id: 0 bus info: pci@0000:01:00.0 version: 00 width: 32 bits clock: 33MHz capabilities: pm pciexpress msi vga_controller bus_master cap_list rom configuration: driver=radeon latency=0 resources: irq:46 memory:d0000000-dfffffff ioport:2000(size=256) memory:cfef0000-cfefffff memory:cfe00000-cfe1ffff

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• Character movement on a 2D tile map

  - by Chris Morris

  I'm working at making a HTML5 game. Top down, closest thing I can equate it to is the gameboy zeldas, but open world and no rooms. What I have so far is a procedurally generated map in a multi dimensional array. And a starting position on the map. Along with this I have an array of movable and non movable tile ID's. I also have a class for my player and have him being rendered out in the center of the starting tile. My problem however is getting the movement sorted out for the player. I want to be able to have the character free move around the map (pixel by pixel essentially) ontop of this 2D generated world. Ideally this would allow the user to move around the walk able area of the canvas. this is simple enough for me to do, but I am having problems now moving the world. If the user is 20% from the edge of the screen i want the world to start panning in the direction the player is heading. But I'm rather lacking in ideas of how to do this. I've looked around for some tutorials, but am coming up blank on ideas of how to generate the playable area (zoomed in) and to then move this generated area under the player when they reach near the end of the screen. My current idea was to generate a certain amount of tiles full size to fill the screen and place the player i the middle. Then when the user approaches the edge of the screen start generating the tiles offset by the distance moved and the direction. I can kind of see this working but I really have no idea if this is the best or easiest to code of methods for generating the world. sorry for the lack of code but I'm still just in the theory stages of working this all out.

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• How does one rein in the complexities of web development ?

  - by Rahul

  I have been a server-side programmer for most of my career and have only recently started spending more time on web development. I am amazed at the number of things I need to master in order to write a decent web application. Just to list down a few tools/technologies I need to learn, Server side programming language (Java/JSP, ASP, PHP, Ruby or something else) A decent web framework (for any medium to big size application). HTML & CSS Javascript Javascript library (JQuery/ExtJS etc. primarily for AJAX). Good to know even if not necessary. At least a basic knowledge of web design - layouts, colors, fonts etc. A good understanding of web security. A good understanding of Performance/scalability issues. Testing, browser compatibility issues etc. The list goes on. So, my question to seasoned web developers is - How do you guys manage to learn and keep yourself updated on so many things? While developing a web application, how do you handle the complexities involved in these areas and yet manage to write an application that is well designed, user friendly, secure, performant and scalable. As a web developer, does one have to be a jack of all trades or should one specialize in one or two areas and leave the rest to other members of the team ?

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• How do I create an encrypted file system inside a file?

  - by darent

  Recently i've found this interesting tutorial: http://flossstuff.wordpress.com/2011/08/07/using-a-file-as-a-storage-device/ It explains how to create an empty file, format it as ext4, and mount it as a device. I'd like to know if it can be created as an encrypted ext4 file system. I've tried using palimpsest (the disk utility found in System menu) to format the already created file system but it doesn't works as it detects the file system being used. If I try to unmount the file system, it won't work neither because it doesn't detect the device (since it's not a real device like a hardrive or a usb drive). So my question is, is there an option to create the file system encrypted from the begining? I've used these commands: Create an empty file 200Mb size: dd if=/dev/zero of=/path/to/file bs=1M count=200 Make it ext4: mkfs -t ext4 file Mount it in a folder inside my home: sudo mount -o loop file /path/to/mount_point Is there any way the mkfs command creates the ext4 encrypted asking for a decryption password? I'm planing to use this as a way to encrypt files inside Dropbox. Thanks for your time.

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• df shows partition as full, but du shows it as only 25% full

  - by Jakobud

  I have a humble linux server to do some stuff for me. I only have an old 16gig drive in it. df -h Filesystem Size Used Avail Use% Mounted on /dev/md1 16G 16G 0 100% / /dev/md0 121M 14M 101M 13% /boot tmpfs 502M 0 502M 0% /dev/shm but when I do: du -sh / 3.5G / So one says that my 16G drive is full. The other says only 3.5G is used. Why the discrepancy? I cannot write any new files as it says the drive is indeed full. But if I can't find the files taking up all the space on the file-system, how can I delete them to free up space?

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• What are the hard and fast rules for Cache Control?

  - by Metalshark

  Confession: sites I maintain have different rules for Cache Control mostly based on the default configuration of the server followed up with recommendations from the Page Speed & Y-Slow Firefox plug-ins and the Network Resources view in Google's Speed Tracer. Cache-Control is set to private/public depending on what they say to do, ETag's/Last-Modified headers are only tinkered with if Y-Slow suggests there is something wrong and Vary-Accept-Encoding seems necessary when manually gziping files for Amazon CloudFront. When reading through the material on the different options and what they do there seems to be conflicting information, rules for broken proxies and cargo cult configurations. Any of the official information provided by the analysis tools mentioned above is quite inaccessible as it deals with each topic individually instead of as a unified strategy (so there is no cross-referencing of techniques). For example, it seems to make no sense that the speed analysis tools rate a site with ETag's the same as a site without them if they are meant to help with caching. What are the hard and fast rules for a platform agnostic Cache Control strategy? EDIT: A link through Jeff Atwood's article explains Caching in superb depth. For the record though here are the hard and fast rules: If the file is Compressed using GZIP, etc - use "cache-control: private" as a proxy may return the compressed version to a client that does not support it (the browser cache will hold files marked this way though). Also remember to include a "Vary: Accept-Encoding" to say that it is compressible. Use Last-Modified in conjunction with ETag - belt and braces usage provides both validators, whilst ETag is based on file contents instead of modification time alone, using both covers all bases. NOTE: AOL's PageTest has a carte blanche approach against ETags for some reason. If you are using Apache on more than one server to host the same content then remove the implicitly declared inode from ETags by excluding it from the FileETag directive (i.e. "FileETag MTime Size") unless you are genuinely using the same live filesystem. Use "cache-control: public" wherever you can - this means that proxy servers (and the browser cache) will return your content even if the rest of the page needs HTTP authentication, etc.

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• Rule of thumb for cost vs. savings for code re-use

  - by Styler

  Is it a good rule of thumb to always write code for the intent of re-using it somewhere down the road? Or, depending on the size of the component you are writing, is it better practice to design it for re-use when it makes sense with regards to time spent on it. What is a good rule of thumb for spending extra time on analysis and design on project components that have "some probability" of being needed later down the road for other things that may or may need this part. For example, if I have the need for project X to do things A, and B. A definitely needs to be written for re-use because it just makes sense to do so. B is very project specific at the moment, and I can hack it all together in a couple days to finish the project on time and give everyone kudos for being a great team, etc. Or if we say, lets spend a whole friggin' 2 weeks figuring out what project Y/Z might need this thing for and spend a load of extra time on on part B because someday we might need to use it on project Y/Z (where the savings will be realized). I'd imagine a perfect world situation would be a nicely crafted combination of project specific vs. re-use architected components given the project. However some code shops might feel it would be a great idea to write everything for the intention of using it at some point down the road.

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• How many copies are needed to enlarge an array?

  - by user10326

  I am reading an analysis on dynamic arrays (from the Skiena's algorithm manual). I.e. when we have an array structure and each time we are out of space we allocate a new array of double the size of the original. It describes the waste that occurs when the array has to be resized. It says that (n/2)+1 through n will be moved at most once or not at all. This is clear. Then by describing that half the elements move once, a quarter of the elements twice, and so on, the total number of movements M is given by: This seems to me that it adds more copies than actually happen. E.g. if we have the following: array of 1 element +--+ |a | +--+ double the array (2 elements) +--++--+ |a ||b | +--++--+ double the array (4 elements) +--++--++--++--+ |a ||b ||c ||c | +--++--++--++--+ double the array (8 elements) +--++--++--++--++--++--++--++--+ |a ||b ||c ||c ||x ||x ||x ||x | +--++--++--++--++--++--++--++--+ double the array (16 elements) +--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--+ |a ||b ||c ||c ||x ||x ||x ||x || || || || || || || || | +--++--++--++--++--++--++--++--++--++--++--++--++--++--++--++--+ We have the x element copied 4 times, c element copied 4 times, b element copied 4 times and a element copied 5 times so total is 4+4+4+5 = 17 copies/movements. But according to formula we should have 1*(16/2)+2*(16/4)+3*(16/8)+4*(16/16)= 8+8+6+4=26 copies of elements for the enlargement of the array to 16 elements. Is this some mistake or the aim of the formula is to provide a rough upper limit approximation? Or am I missunderstanding something here?

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• XNA texture stretching at extreme coordinates

  - by Shaun Hamman

  I was toying around with infinitely scrolling 2D textures using the XNA framework and came across a rather strange observation. Using the basic draw code: spriteBatch.Begin(SpriteSortMode.Deferred, null, SamplerState.PointWrap, null, null); spriteBatch.Draw(texture, Vector2.Zero, sourceRect, Color.White, 0.0f, Vector2.Zero, 2.0f, SpriteEffects.None, 1.0f); spriteBatch.End(); with a small 32x32 texture and a sourceRect defined as: sourceRect = new Rectangle(0, 0, Window.ClientBounds.Width, Window.ClientBounds.Height); I was able to scroll the texture across the window infinitely by changing the X and Y coordinates of the sourceRect. Playing with different coordinate locations, I noticed that if I made either of the coordinates too large, the texture no longer drew and was instead replaced by either a flat color or alternating bands of color. Tracing the coordinates back down, I found the following at around (0, -16,777,000): As you can see, the texture in the top half of the image is stretched vertically. My question is why is this occurring? Certainly I can do things like bind the x/y position to some low multiple of 32 to give the same effect without this occurring, so fixing it isn't an issue, but I'm curious about why this happens. My initial thought was perhaps it was overflowing the coordinate value or some such thing, but looking at a data type size chart, the next closest below is an unsigned short with a range of about 32,000, and above is an unsigned int with a range of around 2,000,000,000 so that isn't likely the cause.

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• Logic that can traverse all possible layouts, but not checking every combination of identical pieces?

  - by George Bailey

  Suppose we have a grid of arbitrary size, which is filled by blocks of various widths and heights. There are many 2x2 blocks (meaning they take a total of 4 cells in the grid) and many 3x3 blocks, as well as some 5x4, 4x5, 2x3, etc. I was hoping I could set up a program that would look at all possible layouts, and rank them, and find the best one. Simply it would look at all possible positions of these blocks, and see what setup is the best rank. (the rank based on how many of these can be connected by a roadway system of 1x1 road blocks, and how many squares can be left empty after this is done. - wanting to fit the most blocks as possible with the least roads.) My question, is how should I traverse all the possibilities? I could take all the blocks and try them one at a time, but since all 2x2 blocks are equal, and there are a couple dozen of them, there is no point in trying every combination there, as in the following AA BBB AA BBB CCBBB CCEEE DD EEE DD EEE is exactly the same as CC EEE CC EEE AAEEE AABBB DD BBB DD BBB You notice that there are 2 3x3 blocks and 3 2x2 blocks in my two examples. Based on the model I have now, the computer would try both of these combinations, as well as many others. The problem is that it is going to try every single possible variation of my couple dozen 2x2 blocks. And that is sorely inefficient. Is there a reasonable way to take out this duplicated work, somehow getting the computer program to treat all 2x2 blocks as equal/identical, instead of one requiring rearranging/swapping of these identical blocks? Can this be done?

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