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• Ubuntu 12.04 Automounting ntfs partition

  - by kuzyt

  Ive looked everywhere to fix this problem but I cant seem to figure out why its doing this. I have the following /etc/fstab entry to mount a ntfs partition using ntfs-3g. UUID=01CD842715EC2180 /media/mediahd02 ntfs defaults,user,noexec,uid=1000,gid=1000,dmask=007,fmask=117 0 2 The volume label for this partition is "MEDIA02" So I have had no problems with the fstab mounting. The problem however is that it automounts again using MEDIA02 label. I'm not sure automounting is the right term for this as its just an empty directory. Deleting this directory and rebooting is causing it to appear again. So listing /media I see both MEDIA02 & mediahd02 htpc@htpc:~$ cat /etc/fstab # /etc/fstab: static file system information. # # Use 'blkid' to print the universally unique identifier for a # device; this may be used with UUID= as a more robust way to name devices # that works even if disks are added and removed. See fstab(5). # # <file system> <mount point> <type> <options> <dump> <pass> proc /proc proc nodev,noexec,nosuid 0 0 # / was on /dev/sdf1 during installation UUID=ec027544-b0e7-4145-99a4-905543a9781a / ext4 errors=remount-ro,noatime,discard 0 1 # swap was on /dev/sdf5 during installation UUID=1794409e-723f-41ac-9f31-ae059f377613 none swap sw 0 0 # Added all the lines below this tmpfs /tmp tmpfs defaults,noatime,mode=1777 0 0 UUID=0F70-3B06 /media/mediahd01 vfat defaults,user,noexec,uid=1000,gid=1000,dmask=007,fmask=117 0 2 UUID=01CD842715EC2180 /media/mediahd02 ntfs defaults,user,noexec,uid=1000,gid=1000,dmask=007,fmask=117 0 2 htpc@htpc:~$ cat /etc/mtab /dev/sdc1 / ext4 rw,noatime,errors=remount-ro,discard 0 0 proc /proc proc rw,noexec,nosuid,nodev 0 0 sysfs /sys sysfs rw,noexec,nosuid,nodev 0 0 none /sys/fs/fuse/connections fusectl rw 0 0 none /sys/kernel/debug debugfs rw 0 0 none /sys/kernel/security securityfs rw 0 0 udev /dev devtmpfs rw,mode=0755 0 0 devpts /dev/pts devpts rw,noexec,nosuid,gid=5,mode=0620 0 0 tmpfs /tmp tmpfs rw,noatime,mode=1777 0 0 tmpfs /run tmpfs rw,noexec,nosuid,size=10%,mode=0755 0 0 none /run/lock tmpfs rw,noexec,nosuid,nodev,size=5242880 0 0 none /run/shm tmpfs rw,nosuid,nodev 0 0 /dev/sdc1 /media/usbhd-sdc1 ext4 rw,relatime 0 0 /dev/sdb1 /media/mediahd02 fuseblk rw,noexec,nosuid,nodev,allow_other,default_permissions,blksize=4096 0 0 /dev/sda5 /media/mediahd01 vfat rw,noexec,nosuid,nodev,uid=1000,gid=1000,dmask=007,fmask=117 0 0 /dev/sdh1 /media/Windows_7 fuseblk rw,nosuid,nodev,allow_other,blksize=4096 0 0 Can someone shed some light as to why its doing this ?

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• Playing with F#

  - by mroberts

  Project Euler is a awesome site.   When working with a new language it can be tricky to find problems that need solving, that are more complex than "Hello World" and simpler than a full blown application. Project Euler gives use just that, cool and thought provoking problems that usually don't take days to solve.  I've solved a number of questions with C# and some with Java.  BTW, I used Java because it had BigInteger support before .Net. A couple weeks ago, back when winter had a firm grip on Columbus, OH, I began playing (researching) with F#.  I began with Problem #1 from Project Euler.  I started by looking at my solution in C#. Here is my solution in C#. 1: using System; 2: using System.Collections.Generic; 3:   4: namespace Problem001 5: { 6: class Program 7: { 8: static void Main(string[] args) 9: { 10: List<int> values = new List<int>(); 11:   12: for (int i = 1; i < 1000; i++) 13: { 14: if (i % 3 == 0 || i % 5 == 0) 15: values.Add(i); 16: } 17: int total = 0; 18:   19: values.ForEach(v => total += v); 20:   21: Console.WriteLine(total); 22: Console.ReadKey(); 23: } 24: } 25: }   Now, after much tweaking and learning, here is my solution in F#.   1: open System 2:   3: let calc n = 4: [1..n] 5: |> List.map (fun x -> if (x % 3 = 0 || x % 5 = 0) then x else 0) 6: |> List.sum 7:   8: let main() = 9: calc 999 10: |> printfn "result = %d" 11: Console.ReadKey(true) |> ignore 12:   13: main() Just this little example highlights some cool things about F#. Type inference. F# infers the type of a value.  In the C# code above we declare a number of variables, the list, and a couple ints.  F# does not require this, it infers the calc (a function) accepts a int and returns a int. Great built in functionality for Lists.  List.map for example. BTW, I don’t think I’m spilling the beans by giving away the code for Problem 1.  It by far is the easiest question, IMHO, solved by 92,000+ people. Next I’ll look into writing a class library with F#.

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• Oracle JDeveloper 11gR2 Cookbook book review

  - by Chris Muir

  I recently received a free copy of Oracle JDeveloper 11gR2 Cookbook published by Packt Publishing for review. Readers of technical cookbooks would know this genre of text includes problems that developers will hit and the prescribed solutions, in this case for Oracle's Application Development Framework (ADF).  Books like this excel themselves on excellent coverage, a logical progress of solutions through out the book, and providing a readable narrative around the numerous steps and code. This book progresses well through ADF application assembly, ADF Business Components, the view layer, security, deployment and tuning.  Each recipe had a clear introduction and I especially enjoyed the "There's more" follow up sections for some recipes that leads the reader onto related ideas and issues the reader really needs to be aware of. Also worthy of comment having worked with ADF for over 5 years, there certainly was recipes and solutions I hadn't encountered before, this book gets bonus points for that. As a reviewer what negatives can I give this text? The book has cast it's net too wide by trying to cover "everything from design and construction, to deployment, testing, debugging and optimization."  ADF is such a large and sophistication technology, this book with 100 recipes barely scrapes the surface.  Don't expect all your ADF problems to be solved here. In turn there is inconsistency in the level of problems and solutions.  I felt at the beginning the book was pitching itself at advanced problems to solve (that's great for me), but then it introduces topics like building a static View Object or train.  These topics in my opinion are fairly simple and are covered by the Oracle documentation just as well, they shouldn't have been included here.  In conclusion, ADF beginners will find this book worthwhile as it will open your eyes to the wider problems and solutions required for ADF, and experts for just the fact they can point junior programmers at the book for certain problems and say "get on with it". Is there scope for more ADF tombs like this?  Yes!  I'd love to see a cookbook specializing on ADF Business Components (hint hint to budding authors).

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• Unable to Mount an external hard drive (NTFS)

  - by Mediterran81

  Ubuntu 11.10. When I plug my external Drive Western Digital MyPassport (500Go NTFS) I named WD. I get the following error: Unable to mount WD Error mounting: mount exited with exit code 1: helper failed with: mount: according to mtab, /dev/sdb1 is already mounted on /media/WD mount failed I have no problem with the internal NTFS partitions that auto-mounts on startup (ntfs-config does that). If I plug the WD before I boot Ubuntu, upon login, it's recognized and I can access without no problem. But if I remove it using (Safely remove) and then replug it, I get the error above. Here is my fstab: # /etc/fstab: static file system information. # # <file system> <mount point> <type> <options> <dump> <pass> proc /proc proc nodev,noexec,nosuid 0 0 #Entry for /dev/sda5 : UUID=24540d0f-5803-493c-ace9-e3b3c0cedb26 / ext4 errors=remount-ro 0 1 #Entry for /dev/sda3 : UUID=E4C43F7EC43F51D2 /media/OS ntfs-3g defaults,locale=en_US.UTF-8 0 0 #Entry for /dev/sda2 : UUID=6A0070F10070C61B /media/RECOVERY ntfs-3g defaults,locale=en_US.UTF-8 0 0 #Entry for /dev/sdb1 : UUID=EA6854D268549F5F /media/WD ntfs-3g defaults,nosuid,nodev,locale=en_US.UTF-8 0 0 #Entry for /dev/sda6 : UUID=ed077c52-c50e-406c-9120-9cb6f86ec204 none swap sw 0 0 Here is my mtab /dev/sda5 / ext4 rw,errors=remount-ro,commit=0 0 0 proc /proc proc rw,noexec,nosuid,nodev 0 0 sysfs /sys sysfs rw,noexec,nosuid,nodev 0 0 fusectl /sys/fs/fuse/connections fusectl rw 0 0 none /sys/kernel/debug debugfs rw 0 0 none /sys/kernel/security securityfs rw 0 0 udev /dev devtmpfs rw,mode=0755 0 0 devpts /dev/pts devpts rw,noexec,nosuid,gid=5,mode=0620 0 0 tmpfs /run tmpfs rw,noexec,nosuid,size=10%,mode=0755 0 0 none /run/lock tmpfs rw,noexec,nosuid,nodev,size=5242880 0 0 none /run/shm tmpfs rw,nosuid,nodev 0 0 /dev/sda3 /media/OS fuseblk rw,nosuid,nodev,allow_other,blksize=4096 0 0 /dev/sda2 /media/RECOVERY fuseblk rw,nosuid,nodev,allow_other,blksize=4096 0 0 /dev/sdb1 /media/WD fuseblk rw,nosuid,nodev,allow_other,blksize=4096 0 0 binfmt_misc /proc/sys/fs/binfmt_misc binfmt_misc rw,noexec,nosuid,nodev 0 0 gvfs-fuse-daemon /home/hanine/.gvfs fuse.gvfs-fuse-daemon rw,nosuid,nodev,user=hanine 0 0 Appearently it cannot be mounted because upon login, it finds that it is already mounted. Some sort of conflict. Does anyone have a clue on how to solve this. Thanks.

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• No client internet access when setting up these iptables rules

  - by Siriss

  I have read many other posts but cannot figure this out. eth0 is my external connected to a Comcast modem. The server has internet access with no issues. eth1 is internal and running DHCP for the clients. I have DHCP working just fine, all my clients can get an IP and ping the server but they cannot access the internet. I am using ISC-DHCP-SERVER and have set /etc/default/isc-dhcp-server to INTERFACE="eht1" Here is my dhcpd.conf file located in /etc/dhcp/dhcpd.conf ddns-update-style interim; ignore client-updates; subnet 10.0.10.0 netmask 255.255.255.0 { range 10.0.10.10 10.0.10.200; option routers 10.0.10.2; option subnet-mask 255.255.255.0; option domain-name-servers 208.67.222.222, 208.67.220.220; #OpenDNS # option domain-name "example.com"; default-lease-time 21600; max-lease-time 43200; authoritative; } I have made the *net.ipv4.ip_forward=1* change in /etc/sysctl.conf here is my interfaces file: auto lo iface lo inet loopback auto eth0 iface eth0 inet dhcp iface eth1 inet static address 10.0.10.2 netmask 255.255.255.0 network 10.0.10.0 auto eth1 And finally- here is my iptables.conf file: # Firewall configuration written by system-config-firewall # Manual customization of this file is not recommended. *nat :PREROUTING ACCEPT [0:0] :OUTPUT ACCEPT [0:0] :POSTROUTING ACCEPT [0:0] -A POSTROUTING -s 10.0.10.0/24 -o eth0 -j MASQUERADE #-A PREROUTING -i eth0 -p tcp --dport 59668 -j DNAT --to-destination 10.0.10.2:59668 COMMIT *filter :INPUT ACCEPT [0:0] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [0:0] -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT -A INPUT -p icmp -j ACCEPT -A INPUT -i lo -j ACCEPT -A INPUT -i eth1 -j ACCEPT -A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT -A INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT -A INPUT -m state --state NEW -m tcp -p tcp --dport 443 -j ACCEPT -A INPUT -m state --state NEW -m tcp -p tcp --dport 53 -j ACCEPT -A INPUT -m state --state NEW -m udp -p udp --dport 53 -j ACCEPT -A FORWARD -s 10.0.10.0/24 -o eth0 -j ACCEPT -A FORWARD -d 10.0.10.0/24 -m state --state ESTABLISHED,RELATED -i eth0 -j ACCEPT -A FORWARD -p icmp -j ACCEPT -A FORWARD -i lo -j ACCEPT -A FORWARD -i eth1 -j ACCEPT #-A FORWARD -i eth0 -m state --state NEW -m tcp -p tcp -d 10.0.10.2 --dport 59668 -j ACCEPT -A INPUT -j REJECT --reject-with icmp-host-prohibited -A FORWARD -j REJECT --reject-with icmp-host-prohibited COMMIT I am completely stuck. I cannot figure out why the clients cannot access the internet. Am I missing a service? Is a service not running? Any help would be greatly appreciated. I tried to be as thorough as possible but please let me know if I have missed something. Thank you!

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• Server-infrastructure recommendations

  - by Tim van Elsloo

  Here's the thing: I need a cheap, fast, reliable infrastructure that can dynamically scale (like Amazon S3: cloud-storage). I'm thinking of 3 different type of 'servers'. Application-server Should be able to run CentOS (or another light Linux-distr.) Should be able to run Apache Should be able to run PHP Should be able to run GD (so it does rely on it's cpu). Should be extremely reliable and fast. Database-server Should be able to run MySQL Should be able to... well, do nothing else :P. Should be extremely reliable and fast. Storage-server Should be able to run some kind of file-transfer-deamon (like FTP, CouchDB, etc.) Should be able to do nothing else. Should be extremely reliable and fast. So technically, by transferring all static data to 2 different servers/services, the application-server can totally focus on the webpages. My questions: What services do you recommend? Which is cheaper, faster and more reliable: using my own server, or using some cloud-storage/cloud-computing-service (like Amazon S3, CloudFiles, etc.)? How can I prevent bandwidth abuse (such as dos-attacks causing the bill to be extremely high)? What's the difference between "including CDN" and "excluding CDN"? It seems the price doesn't differ at CloudFiles? Do you have to pay "including CDN" + "excluding CDN" when you decide to enable the delivery-network? Or have you only got to pay "including CDN"? Should I use my own nameserver too or can I use my domain-hoster's nameservers? What are the minimum software specifications of a nameserver. Can I write some software myself? Does anyone have a good protocol-description? I hope you can answer my questions. Answers I shouldn't write my own nameserver-software. Instead, I should use something like bind. (http://osspro.com/2010/05/04/linux-create-your-own-domain-name-server-dns/).

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• C# Dev - I've tried Lisps, but I don't get it.

  - by Jonathan Mitchem

  After a few months of learning about and playing with lisps, both CL and a bit of Clojure, I'm still not seeing a compelling reason to write anything in it instead of C#. I would really like some compelling reasons, or for someone to point out that I'm missing something really big. The strengths of a Lisp (per my research): Compact, expressive notation - More so than C#, yes... but I seem to be able to express those ideas in C# too. Implicit support for functional programming - C# with LINQ extension methods: mapcar = .Select( lambda ) mapcan = .Select( lambda ).Aggregate( (a,b) = a.Union(b) ) car/first = .First() cdr/rest = .Skip(1) .... etc. Lambda and higher-order function support - C# has this, and the syntax is arguably simpler: "(lambda (x) ( body ))" versus "x = ( body )" "#(" with "%", "%1", "%2" is nice in Clojure Method dispatch separated from the objects - C# has this through extension methods Multimethod dispatch - C# does not have this natively, but I could implement it as a function call in a few hours Code is Data (and Macros) - Maybe I haven't "gotten" macros, but I haven't seen a single example where the idea of a macro couldn't be implemented as a function; it doesn't change the "language", but I'm not sure that's a strength DSLs - Can only do it through function composition... but it works Untyped "exploratory" programming - for structs/classes, C#'s autoproperties and "object" work quite well, and you can easily escalate into stronger typing as you go along Runs on non-Windows hardware - Yeah, so? Outside of college, I've only known one person who doesn't run Windows at home, or at least a VM of Windows on *nix/Mac. (Then again, maybe this is more important than I thought and I've just been brainwashed...) The REPL for bottom-up design - Ok, I admit this is really really nice, and I miss it in C#. Things I'm missing in a Lisp (due to a mix of C#, .NET, Visual Studio, Resharper): Namespaces. Even with static methods, I like to tie them to a "class" to categorize their context (Clojure seems to have this, CL doesn't seem to.) Great compile and design-time support the type system allows me to determine "correctness" of the datastructures I pass around anything misspelled is underlined realtime; I don't have to wait until runtime to know code improvements (such as using an FP approach instead of an imperative one) are autosuggested GUI development tools: WinForms and WPF (I know Clojure has access to the Java GUI libraries, but they're entirely foreign to me.) GUI Debugging tools: breakpoints, step-in, step-over, value inspectors (text, xml, custom), watches, debug-by-thread, conditional breakpoints, call-stack window with the ability to jump to the code at any level in the stack (To be fair, my stint with Emacs+Slime seemed to provide some of this, but I'm partial to the VS GUI-driven approach) I really like the hype surrounding Lisps and I gave it a chance. But is there anything I can do in a Lisp that I can't do as well in C#? It might be a bit more verbose in C#, but I also have autocomplete. What am I missing? Why should I use Clojure/CL?

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• Wired and Wireless Network Issues with PPPoE

  - by user9054

  down vote favorite Hi Friends, I have got this issue with Ubuntu 10.10. I have been with ubuntu 8.04 and then decided to try out ubuntu 10.10 . I booted with a LiveCD and was able to configure the wireless network painlessly using the livecd. So happily i installed ubuntu 10.10. As soon as ubuntu came up it detected the wireless network and i was able to assign a static IP to eth1 (i dont use DHCP option on my ADSL router) and enter a wap key and use pppoeconf to configure the dialer. The net was on and i was able to surf the net. All hunky dory so far. However on the next boot the fun started. It did not detect the wireless network. I could not see the network manager icon in the systray. I used ifconfig and saw that the entry for eth1 was missing. I used ifup eth1 and it said that eth1 was already up . Then i installed wifi-radar. Wifi-Radar detected the wireless network. I configured wifi-radar for the detected wireless network , set the wap driver as wext and used the manual IP settings. However on clicking connect wifi-radar started looking for a DHCP IP , needless to say it failed. For the love of god i cannot understand why wifi-radar is using DHCP when i have specified manual settings . Next i decided to use the wired network to surf the net looking for a solution . So i plugged in the network cable from my modem , it detected the plugged in connection , i configured eth0 , used pppoeconf and connected to the net. Then i foolishly decided to reboot my PC. And wonders of wonders , the same problem appeared. I cannot see eth0 in my ifconfig anymore. I used pon to start the dsl-provider connection and it said something about network error or something . Now my ifconfig shows only lo , both eth0 and eth1 have disappeared. Can anybody help me on this ? Is it a problem with ipv6 , if so how do you disable ipv6 on ubuntu 10.10 ? OR is this is a known issue with ubuntu 10.10 ? PS : 1) i tried linux mint 10 and had the same issue. On rebooting wireless network was not getting detected . 2) i have made myself the administrator so that there is no issue of rights or anything. Any help is appreciated.

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• Wrapping REST based Web Service

  - by PaulPerry

  I am designing a system that will be running online under Microsoft Windows Azure. One component is a REST based web service which will really be a wrapper (using proxy pattern) which calls the REST web services of a business partner, which has to do with BLOB storage (note: we are not using azure storage). The majority of the functionality will be taking a request, calling our partner web service, receiving the request and then passing that back to the client. There are a number of reasons for doing this, but one of the big ones is that we are going to support three clients: our desktop application (win and mac), mobile apps (iOS), and a web front end. Having a single API which we then send to our partner protects us if that partner ever changes. I want our service to support both JSON and XML for the data transfer format, JSON for web and probably XML for the desktop and mobile (we already have an XML parser in those products). Our partner also supports both of these formats. I was planning on using ASP.NET MVC 4 with the Web API. As I design this, the thing that concerns me is the static type checking of C#. What if the partner adds or removes elements from the data? We can probably defensively code for that, but I still feel some concern. Also, we have to do a fair amount of tedious coding, to setup our API and then to turn around and call our partner’s API. There probably is not much choice on it though. But, in the back of my mind I wonder if maybe a more dynamic language would be a better choice. I want to reach out and see if anybody has had to do this before, what technology solutions they have used to (I am not attached to this one, these days Azure can host other technologies), and if anybody who has done something like this can point out any issues that came up. Thanks! Researching the issue seems to only find solutions which focus on connecting a SOAP web service over a proxy server, and not what I am referring to here. Note: Cross posted (by suggestion) from http://stackoverflow.com/questions/11906802/wrapping-rest-based-web-service Thank you!

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• Why won't my vertex buffer render in GLFW3?

  - by sm81095

  I have started to try to learn OpenGL, and I decided to use GLFW to assist in window creation. The problem is, since GLFW3 is so new, there are no tutorials on it or how to use it with modern OpenGL (3.3, specifically). Using the GLFW3 tutorial found on the website, which uses older OpenGL rendering (glBegin(GL_TRIANGLES), glVertex3f(), and such), I can get a triangle to render to the screen. The problem is, using new OpenGL, I can't get the same triangle to render to the screen. I am new to OpenGL, and GLFW3 is new to most people, so I may be completely missing something obvious, but here is my code: static const GLuint g_vertex_buffer_data[] = { -1.0f, -1.0f, 0.0f, 1.0f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f }; int main(void) { GLFWwindow* window; if(!glfwInit()) { fprintf(stderr, "Failed to initialize GLFW."); return -1; } glfwWindowHint(GLFW_SAMPLES, 4); glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3); glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); window = glfwCreateWindow(800, 600, "Test Window", NULL, NULL); if(!window) { glfwTerminate(); fprintf(stderr, "Failed to create a GLFW window"); return -1; } glfwMakeContextCurrent(window); glewExperimental = GL_TRUE; GLenum err = glewInit(); if(err != GLEW_OK) { glfwTerminate(); fprintf(stderr, "Failed to initialize GLEW"); fprintf(stderr, (char*)glewGetErrorString(err)); return -1; } GLuint VertexArrayID; glGenVertexArrays(1, &VertexArrayID); glBindVertexArray(VertexArrayID); GLuint programID = LoadShaders("SimpleVertexShader.glsl", "SimpleFragmentShader.glsl"); GLuint vertexBuffer; glGenBuffers(1, &vertexBuffer); glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer); glBufferData(GL_ARRAY_BUFFER, sizeof(g_vertex_buffer_data), g_vertex_buffer_data, GL_STATIC_DRAW); while(!glfwWindowShouldClose(window)) { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glUseProgram(programID); glEnableVertexAttribArray(0); glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer); glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, (void*)0); glDrawArrays(GL_TRIANGLES, 0, 3); glDisableVertexAttribArray(0); glfwSwapBuffers(window); glfwPollEvents(); } glDeleteBuffers(1, &vertexBuffer); glDeleteProgram(programID); glfwDestroyWindow(window); glfwTerminate(); exit(EXIT_SUCCESS); } I know it is not my shaders, they are super simple and I've checked them against GLFW 2.7 so I know that they work. I'm assuming that I've missed something crucial to using the OpenGL context with GLFW3, so any help locating the problem would be greatly appreciated.

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• cloud programming for OpenStack in C / C++

  - by Basile Starynkevitch

  (Sorry for such a fuzzy question, I am very newbie to cloud programming) I am interested in designing (and developing) a (free software) program in C or C++ (probably, most of it being meta-programmed, i.e. part of the C code code being generated). I am still in the thinking / designing phase. And I might perhaps give up. For reference, I am the main architect and implementor of GCC MELT, a domain specific language to extend the GCC compiler (the MELT language is translated to C/C++ and is bootstrapped: the MELT to C/C++ translator being written in MELT). And I am dreaming of extending it with some cloud computing abilities. But I am a newbie in cloud computing. (I am only interested in free-software, GPLv3 friendly, based cloud computing, which probably means openstack). I believe that "compiling on the cloud with some enhanced GCC" could make sense (for super-optimizations or static analysis of e.g. an entire Linux distribution, or at least a massive GCC compiled free software like Qt, GCC itself, or the Linux kernel). I'm dreaming of a MELT specific monitoring program which would store, communicate, and and enhance GCC compilation (extended by MELT). So the picture would be that each GCC process (actually the cc1 or cc1plus started by the gcc driver, suitably extended by some MELT extension) would communicate with some monitor. That "monitoring/persisting" program would run "on the cloud" (and probably manage some information produced by GCC e.g. on NoSQL bases). So, how should some (yet to be written) C program (some Linux daemon) be designed to be cloud-friendly? So far, I understood that it should provide some Web service, probably thru a RESTful service, so should use an HTTP server library like onion. And that OpenStack is able to start (e.g. a dozen of) such services. But I don't have a clear picture of what OpenStack brings. So far, I noticed the ability to manage (and distribute) virtual machines (with some Python API). It is less clear how can it distribute some ELF executable, how can it start it, etc. Do you have any references or examples of C / C++ programming on the cloud? How should a "cloud-friendly" (actually, OpenStack friendly) C/C++ server application be designed?

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• OpenGL VertexBuffer won'e render in GLFW3

  - by sm81095

  So I have started to try to learn OpenGL, and I decided to use GLFW to assist in window creation. The problem is, since GLFW3 is so new, there are no tutorials on it yet and how to use it with modern OpenGL (3.3, specifically). Using the GLFW3 tutorial found on the website, which uses older OpenGL rendering (glBegin(GL_TRIANGLES), glVertex3f()), and such, I can get a triangle to render to the screen. The problem is, using new OpenGL, I can't get the same triangle to render to the screen. I am new to OpenGL, and GLFW3 is new to most people, so I may be completely missing something obvious, but here is my code: static const GLuint g_vertex_buffer_data[] = { -1.0f, -1.0f, 0.0f, 1.0f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f }; int main(void) { GLFWwindow* window; if(!glfwInit()) { fprintf(stderr, "Failed to initialize GLFW."); return -1; } glfwWindowHint(GLFW_SAMPLES, 4); glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3); glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); window = glfwCreateWindow(800, 600, "Test Window", NULL, NULL); if(!window) { glfwTerminate(); fprintf(stderr, "Failed to create a GLFW window"); return -1; } glfwMakeContextCurrent(window); glewExperimental = GL_TRUE; GLenum err = glewInit(); if(err != GLEW_OK) { glfwTerminate(); fprintf(stderr, "Failed to initialize GLEW"); fprintf(stderr, (char*)glewGetErrorString(err)); return -1; } GLuint VertexArrayID; glGenVertexArrays(1, &VertexArrayID); glBindVertexArray(VertexArrayID); GLuint programID = LoadShaders("SimpleVertexShader.glsl", "SimpleFragmentShader.glsl"); GLuint vertexBuffer; glGenBuffers(1, &vertexBuffer); glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer); glBufferData(GL_ARRAY_BUFFER, sizeof(g_vertex_buffer_data), g_vertex_buffer_data, GL_STATIC_DRAW); while(!glfwWindowShouldClose(window)) { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glUseProgram(programID); glEnableVertexAttribArray(0); glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer); glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, (void*)0); glDrawArrays(GL_TRIANGLES, 0, 3); glDisableVertexAttribArray(0); glfwSwapBuffers(window); glfwPollEvents(); } glDeleteBuffers(1, &vertexBuffer); glDeleteProgram(programID); glfwDestroyWindow(window); glfwTerminate(); exit(EXIT_SUCCESS); } I know it is not my shaders, they are super simple and I've checked them against GLFW 2.7 so I know that they work. I'm assuming that I've missed something crucial to using the OpenGL context with GLFW3, so any help locating the problem would be greatly appreciated.

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• Data Transformation Pipeline

  - by davenewza

  I have create some kind of data pipeline to transform coordinate data into more useful information. Here is the shell of pipeline: public class PositionPipeline { protected List<IPipelineComponent> components; public PositionPipeline() { components = new List<IPipelineComponent>(); } public PositionPipelineEntity Process(Position position) { foreach (var component in components) { position = component.Execute(position); } return position; } public PositionPipeline RegisterComponent(IPipelineComponent component) { components.Add(component); return this; } } Every IPipelineComponent accepts and returns the same type - a PositionPipelineEntity. Code: public interface IPipelineComponent { PositionPipelineEntity Execute(PositionPipelineEntity position); } The PositionPipelineEntity needs to have many properties, many which are unused in certain components and required in others. Some properties will also have become redundant at the end of the pipeline. For example, these components could be executed: TransformCoordinatesComponent: Parse the raw coordinate data into a Coordinate type. DetermineCountryComponent: Determine and stores country code. DetermineOnRoadComponent: Determine and store whether coordinate is on a road. Code: pipeline .RegisterComponent(new TransformCoordinatesComponent()) .RegisterComponent(new DetermineCountryComponent()) .RegisterComponent(new DetermineOnRoadComponent()); pipeline.Process(positionPipelineEntity); The PositionPipelineEntity type: public class PositionPipelineEntity { // Only relevant to the TransformCoordinatesComponent public decimal RawCoordinateLatitude { get; set; } // Only relevant to the TransformCoordinatesComponent public decimal RawCoordinateLongitude { get; set; } // Required by all components after TransformCoordinatesComponent public Coordinate CoordinateLatitude { get; set; } // Required by all components after TransformCoordinatesComponent public Coordinate CoordinateLongitude { get; set; } // Set in DetermineCountryComponent, not required anywhere. // Requires CoordinateLatitude and CoordinateLongitude (TransformCoordinatesComponent) public string CountryCode { get; set; } // Set in DetermineOnRoadComponent, not required anywhere. // Requires CoordinateLatitude and CoordinateLongitude (TransformCoordinatesComponent) public bool OnRoad { get; set; } } Problems: I'm very concerned about the dependency that a component has on properties. The way to solve this would be to create specific types for each component. The problem then is that I cannot chain them together like this. The other problem is the order of components in the pipeline matters. There is some dependency. The current structure does not provide any static or runtime checking for such a thing. Any feedback would be appreciated.

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• Drawing a texture at the end of a trace (crosshair?) UDK

  - by Dave Voyles

  I'm trying to draw a crosshair at the end of my trace. If my crosshair does not hit a pawn or static mesh (ex, just a skybox) then the crosshair stays locked on a certain point at that actor - I want to say its origin. Ex: Run across a pawn, then it turns yellow and stays on that pawn. If it runs across the skybox, then it stays at one point on the box. Weird? How can I get my crosshair to stay consistent? I've included two images for reference, to help illustrate. Note: The wrench is actually my crosshair. The "X" is just a debug crosshair. Ignore that. /// Image 1 /// /// Image 2 /// /*************************************************************************** * Draws the crosshair ***************************************************************************/ function bool CheckCrosshairOnFriendly() { local float CrosshairSize; local vector HitLocation, HitNormal, StartTrace, EndTrace, ScreenPos; local actor HitActor; local MyWeapon W; local Pawn MyPawnOwner; /** Sets the PawnOwner */ MyPawnOwner = Pawn(PlayerOwner.ViewTarget); /** Sets the Weapon */ W = MyWeapon(MyPawnOwner.Weapon); /** If we don't have an owner, then get out of the function */ if ( MyPawnOwner == None ) { return false; } /** If we have a weapon... */ if ( W != None) { /** Values for the trace */ StartTrace = W.InstantFireStartTrace(); EndTrace = StartTrace + W.MaxRange() * vector(PlayerOwner.Rotation); HitActor = MyPawnOwner.Trace(HitLocation, HitNormal, EndTrace, StartTrace, true, vect(0,0,0),, TRACEFLAG_Bullet); DrawDebugLine(StartTrace, EndTrace, 100,100,100,); /** Projection for the crosshair to convert 3d coords into 2d */ ScreenPos = Canvas.Project(HitLocation); /** If we haven't hit any actors... */ if ( Pawn(HitActor) == None ) { HitActor = (HitActor == None) ? None : Pawn(HitActor.Base); } } /** If our trace hits a pawn... */ if ((Pawn(HitActor) == None)) { /** Draws the crosshair for no one - Grey*/ CrosshairSize = 28 * (Canvas.ClipY / 768) * (Canvas.ClipX /1024); Canvas.SetDrawColor(100,100,128,255); Canvas.SetPos(ScreenPos.X - (CrosshairSize * 0.5f), ScreenPos.Y -(CrosshairSize * 0.5f)); Canvas.DrawTile(class'UTHUD'.default.AltHudTexture, CrosshairSize, CrosshairSize, 600, 262, 28, 27); return false; } /** Draws the crosshair for friendlies - Yellow */ CrosshairSize = 28 * (Canvas.ClipY / 768) * (Canvas.ClipX /1024); Canvas.SetDrawColor(255,255,128,255); Canvas.SetPos(ScreenPos.X - (CrosshairSize * 0.5f), ScreenPos.Y -(CrosshairSize * 0.5f)); Canvas.DrawTile(class'UTHUD'.default.AltHudTexture, CrosshairSize, CrosshairSize, 600, 262, 28, 27); return true; }

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• Isometric layer moving inside map

  - by gronzzz

  i'm created isometric map and now trying to limit layer moving. Main idea, that i have left bottom, right bottom, left top, right top points, that camera can not move outside, so player will not see map out of bounds. But i can not understand algorithm of how to do that. It's my layer scale/moving code. - (void)touchBegan:(UITouch *)touch withEvent:(UIEvent *)event { _isTouchBegin = YES; } - (void)touchMoved:(UITouch *)touch withEvent:(UIEvent *)event { NSArray *allTouches = [[event allTouches] allObjects]; UITouch *touchOne = [allTouches objectAtIndex:0]; CGPoint touchLocationOne = [touchOne locationInView: [touchOne view]]; CGPoint previousLocationOne = [touchOne previousLocationInView: [touchOne view]]; // Scaling if ([allTouches count] == 2) { _isDragging = NO; UITouch *touchTwo = [allTouches objectAtIndex:1]; CGPoint touchLocationTwo = [touchTwo locationInView: [touchTwo view]]; CGPoint previousLocationTwo = [touchTwo previousLocationInView: [touchTwo view]]; CGFloat currentDistance = sqrt( pow(touchLocationOne.x - touchLocationTwo.x, 2.0f) + pow(touchLocationOne.y - touchLocationTwo.y, 2.0f)); CGFloat previousDistance = sqrt( pow(previousLocationOne.x - previousLocationTwo.x, 2.0f) + pow(previousLocationOne.y - previousLocationTwo.y, 2.0f)); CGFloat distanceDelta = currentDistance - previousDistance; CGPoint pinchCenter = ccpMidpoint(touchLocationOne, touchLocationTwo); pinchCenter = [self convertToNodeSpace:pinchCenter]; CGFloat predictionScale = self.scale + (distanceDelta * PINCH_ZOOM_MULTIPLIER); if([self predictionScaleInBounds:predictionScale]) { [self scale:predictionScale scaleCenter:pinchCenter]; } } else { // Dragging _isDragging = YES; CGPoint previous = [[CCDirector sharedDirector] convertToGL:previousLocationOne]; CGPoint current = [[CCDirector sharedDirector] convertToGL:touchLocationOne]; CGPoint delta = ccpSub(current, previous); self.position = ccpAdd(self.position, delta); } } - (void)touchEnded:(UITouch *)touch withEvent:(UIEvent *)event { _isDragging = NO; _isTouchBegin = NO; // Check if i need to bounce _touchLoc = [touch locationInNode:self]; } #pragma mark - Update - (void)update:(CCTime)delta { CGPoint position = self.position; float scale = self.scale; static float friction = 0.92f; //0.96f; if(_isDragging && !_isScaleBounce) { _velocity = ccp((position.x - _lastPos.x)/2, (position.y - _lastPos.y)/2); _lastPos = position; } else { _velocity = ccp(_velocity.x * friction, _velocity.y *friction); position = ccpAdd(position, _velocity); self.position = position; } if (_isScaleBounce && !_isTouchBegin) { float min = fabsf(self.scale - MIN_SCALE); float max = fabsf(self.scale - MAX_SCALE); int dif = max > min ? 1 : -1; if ((scale > MAX_SCALE - SCALE_BOUNCE_AREA) || (scale < MIN_SCALE + SCALE_BOUNCE_AREA)) { CGFloat newSscale = scale + dif * (delta * friction); [self scale:newSscale scaleCenter:_touchLoc]; } else { _isScaleBounce = NO; } } }

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• Gettings Terms asscoiated to a Specific list item

  - by Gino Abraham

  I had a fancy requirement where i had to get all tags associated to a document set in a document library. The normal tag could webpart was not working when i add it to the document set home page, so planned a custom webpart. Was checking in net to find a straight forward way to achieve this, but was not lucky enough to get something. Since i didnt get any samples in net, i looked into Microsoft.Sharerpoint.Portal.Webcontrols and found a solution.The socialdataframemanager control in 14Hive/Template/layouts/SocialDataFrame.aspx directed me to the solution. You can get the dll from ISAPI folder. Following Code snippet can get all Terms associated to the List Item given that you have list name and id for the list item. using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.SharePoint; using Microsoft.Office.Server.SocialData; namespace TagChecker { class Program { static void Main(string[] args) { // Your site url string siteUrl = http://contoso; // List Name string listName = "DocumentLibrary1"; // List Item Id for which you want to get all terms int listItemId = 35; using (SPSite site = new SPSite(siteUrl)) { using(SPWeb web = site.OpenWeb()) { SPListItem listItem = web.Lists[listName].GetItemById(listItemId); string url = string.Empty; // Based on the list type the url would be formed. Code Sniffed from Micosoft dlls :) if (listItem.ParentList.BaseType == SPBaseType.DocumentLibrary) { url = listItem.Web.Url.TrimEnd(new char[] { '/' }) + "/" + listItem.Url.TrimStart(new char[] { '/' }); } else if (SPFileSystemObjectType.Folder == listItem.FileSystemObjectType) { url = listItem.Web.Url.TrimEnd(new char[] { '/' }) + "/" + listItem.Folder.Url.TrimStart(new char[] { '/' }); } else { url = listItem.Web.Url.TrimEnd(new char[] { '/' }) + "/" + listItem.ParentList.Forms[PAGETYPE.PAGE_DISPLAYFORM].Url.TrimStart(new char[] { '/' }) + "?ID=" + listItem.ID.ToString(); } SPServiceContext serviceContext = SPServiceContext.GetContext(site); Uri uri = new Uri(url); SocialTagManager mgr = new SocialTagManager(serviceContext); SocialTerm[] terms = mgr.GetTerms(uri); foreach (SocialTerm term in terms) { Console.WriteLine(term.Term.Labels[0].Value ); } } } Console.Read(); } } } Reference dlls added are Microsoft.Sharepoint , Microsoft.Sharepoint.Taxonomy, Microsoft.office.server, Microsoft.Office.Server.UserProfiles from ISAPI folder. This logic can be used to make a custom tag cloud webpart by taking code from OOB tag cloud, so taht you can have you webpart anywhere in the site and still get Tags added to a specifc libdary/List. Hope this helps some one.

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• How to Overcome or fix MIXED_DML_OPERATION error in Salesforce APEX without future method ?

  - by sathya

  How to Overcome or fix MIXED_DML_OPERATION error in Salesforce APEX without future method ?MIXED_DML_OPERATION :-one of the worst issues we have ever faced :)While trying to perform DML operation on a setup object and non-setup object in a single action you will face this error.Following are the solutions I tried and the final one worked out :-1. perform the 1st objects DML on normal apex method. Then Call the 2nd objects DML through a future method.    Drawback :- You cant get a response from the future method as its context is different and because its executing asynchronously and that its static.2. Tried the following option but it didnt work :-    1. perform the dml operation on the normal apex method.    2. tried calling the 2nd dml from trigger thinking that it would be in a different context. But it didnt work.    3. Some suggestions were given in some blogs that we could try System.runas()   Unfortunately that works only for test class.   4. Finally achieved it with response synchronously through the following solution :-    a. Created 2 apex:commandbuttons :-        1. <apex:commandButton value="Save and Send Activation Email" action="{!CreateContact}"  rerender="junkpanel" oncomplete="callSimulateUserSave()">            Note :- Oncomplete will not work if you dont have a rerender attribute. So just try refreshing a junk panel.        2. <apex:commandButton value="SimulateUserSave" id="SimulateUserSave" action="{!SaveUser}"  style="display:none;margin-left:5px;"/>        Have a junk panel as well just for rerendering  :-        <apex:outputPanel id="junkpanel"></apex:outputPanel>    b. Created this javascript function which is called from first button's oncomplete and clicks the second button :-                function callSimulateUserSave()                {                    // Specify the id of the button that needs to be clicked. This id is based on the Apex Component Hierarchy.                    // You will not get this value if you dont have the id attribute in the button which needs to be clicked from javascript                    // If you have any doubt in getting this value. Just hover over the button using Chrome developer tools to get the id.                    // But it will show like theForm:SimulateUserSave but you need to replace the colon with a dot here.                    // Note :- I have given display:none in the style of the second button to make sure that, it is not visible for the user.                    var mybtn=document.getElementById('{!$Component.theForm.SimulateUserSave}');                                    mybtn.click();                }    c. Apex Methods CreateContact and SaveUser are the pagereference methods which contains the code to create contact and user respectively.       After inserting the user inside the second apex method you can just set some public Properties in the page,        for ex:- created userid to get the user details and display in the page to show the acknowledgement to the users that the User is created.

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• Styling Windows Phone Silverlight Applications

  - by Tim Murphy

  If you have not developed with styles in Silverlight/XAML then it can be challenging and resources can be sparse depending on how deep you get.  One thing that you need to understand is what level you can apply styles and how much they can cascade.  What I am finding is that this doesn’t go to the level that we are used to in HTML and CSS. While styles can be defined at a page level if you want to share styles throughout your application they should be defined in the App.xaml file.  This is of course analogous to placing a style in your HTML file versus an external CSS file.  This is the type of style I will concentrate on in this post. The first thing to look it how styles associate to elements.  TargetType defines the object type that your style will apply to.  In the example below the style is targeting the TextBlock object type. <Style x:Key="TextBlockSmallGray" TargetType="TextBlock"> Next we use a Setter which allows you to apply values for specific attributes of the target object type.  The setters can be a simple value or complex.  The first example here is simply applying a color to the background property of the target. <Setter Property="Background" Value="White"/> The second setter example here is for the same property, but we are applying a the definition of a LinearGradientBrush. <Setter Property="Background"> <Setter.Value> <LinearGradientBrush> <GradientStop Offset="0" Color="Black"/> <GradientStop Offset="1" Color="White"/> </LinearGradientBrush> </Setter.Value> </Setter> The last thing I want to cover here is that you can leverage the system styles and then override or extend them.  The BasedOn attribute of the Style tag allows this sort of inheritance.  In the example below I am going to start with the PhoneTextTitleStyle and then override properties as needed. <Style x:Key="TextBlockTitle" BasedOn="{StaticResource PhoneTextTitle1Style}" TargetType="TextBlock"> So now that we have our styles defined applying it is fairly straight forward.  Add the style name as a static resource to the style property of the element in your page and off you go. <Grid x:Name="LayoutRoot" Style="{StaticResource PageGridStyle}"> So this is one step in creating consistency in your application’s look.  In future posts I will dig a little deeper. del.icio.us Tags: windows phone 7,mobile development,windows phone 7 development,.NET,software development,design,UX

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• Fixing a NoClassDefFoundError

  - by Chris Okyen

  I have some code: package ftc; import java.util.Scanner; public class Fer_To_Cel { public static void main(String[] argv) { // Scanner object to get the temp in degrees Farenheit Scanner keyboard = new Scanner(System.in); boolean isInt = true; // temporarily put as true in case the user enters a valid int the first time int degreesF = 0; // initialy set to 0 do { try { // Input the temperature text. System.out.print("\nPlease enter a temperature (integer number, no fractional part) in degrees Farenheit: "); degreesF = Integer.parseInt(keyboard.next()); // Get user input and Assign the far. temperature variable, which is casted from String to int. } // Let the user know in a user friendly notice that the value entered wasnt an int ( give int value range ) , and then give error log catch(java.lang.Exception e) { System.out.println("Sorry but you entered a non-int value ( needs to be between ( including ) -2,147,483,648 and 2,147,483,647 ).. \n"); e.printStackTrace(); isInt = false; } } while(!isInt); System.out.println(""); // print a new line. final int degreesC = (5*(degreesF-32)/9); // convert the degrees from F to C and store the resulting expression in degreesC // Print out a newline, then print what X degrees F is in Celcius. System.out.println("\n" + degreesF + " degrees Farenheit is " + degreesC + " degrees Celcius"); } } And The following error: C:\Program Files\Java\jdk1.7.0_06\bin>java Fer_To_Cel Exception in thread "main" java.lang.NoClassDefFoundError: Fer_To_Cel (wrong name: ftc/Fer_To_Cel) at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:791) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:14 at java.net.URLClassLoader.defineClass(URLClassLoader.java:449) at java.net.URLClassLoader.access$100(URLClassLoader.java:71) at java.net.URLClassLoader$1.run(URLClassLoader.java:361) at java.net.URLClassLoader$1.run(URLClassLoader.java:355) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:354) at java.lang.ClassLoader.loadClass(ClassLoader.java:423) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308) at java.lang.ClassLoader.loadClass(ClassLoader.java:356) at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:480) The code compiled without compile errors, but presented errors during execution. Which leads me to two questions. I know Errors can be termed Compiler, Runtime and Logic Errors, but the NoClassDefFoundError inherits java.lang.LinkageError. Does that make it a Linker error, being niether of the three types of errors I listed, If I am right this is the answer. For someone else who obtains the singular .java file and compiles it, would this be the only way to solve this problem? Or can I (should I ) do/have done something to fix this problem? Basically, based on a basis of programming, is this a fault of me as the writer? Could this be done once on, my half and be distributed and not needed be done again?

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• Software Tuned to Humanity

  - by Phil Factor

  I learned a great deal from a cynical old programmer who once told me that the ideal length of time for a compiler to do its work was the same time it took to roll a cigarette. For development work, this is oh so true. After intently looking at the editing window for an hour or so, it was a relief to look up, stretch, focus the eyes on something else, and roll the possibly-metaphorical cigarette. This was software tuned to humanity. Likewise, a user’s perception of the “ideal” time that an application will take to move from frame to frame, to retrieve information, or to process their input has remained remarkably static for about thirty years, at around 200 ms. Anything else appears, and always has, to be either fast or slow. This could explain why commercial applications, unlike games, simulations and communications, aren’t noticeably faster now than they were when I started programming in the Seventies. Sure, they do a great deal more, but the SLAs that I negotiated in the 1980s for application performance are very similar to what they are nowadays. To prove to myself that this wasn’t just some rose-tinted misperception on my part, I cranked up a Z80-based Jonos CP/M machine (1985) in the roof-space. Within 20 seconds from cold, it had loaded Wordstar and I was ready to write. OK, I got it wrong: some things were faster 30 years ago. Sure, I’d now have had all sorts of animations, wizzy graphics, and other comforting features, but it seems a pity that we have used all that extra CPU and memory to increase the scope of what we develop, and the graphical prettiness, but not to speed the processes needed to complete a business procedure. Never mind the weight, the response time’s great! To achieve 200 ms response times on a Z80, or similar, performance considerations influenced everything one did as a developer. If it meant writing an entire application in assembly code, applying every smart algorithm, and shortcut imaginable to get the application to perform to spec, then so be it. As a result, I’m a dyed-in-the-wool performance freak and find it difficult to change my habits. Conversely, many developers now seem to feel quite differently. While all will acknowledge that performance is important, it’s no longer the virtue is once was, and other factors such as user-experience now take precedence. Am I wrong? If not, then perhaps we need a new school of development technique to rival Agile, dedicated once again to producing applications that smoke the rear wheels rather than pootle elegantly to the shops; that forgo skeuomorphism, cute animation, or architectural elegance in favor of the smell of hot rubber. I struggle to name an application I use that is truly notable for its blistering performance, and would dearly love one to do my everyday work – just as long as it doesn’t go faster than my brain.

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• Per-pixel collision detection - why does XNA transform matrix return NaN when adding scaling?

  - by JasperS

  I looked at the TransformCollision sample on MSDN and added the Matrix.CreateTranslation part to a property in my collision detection code but I wanted to add scaling. The code works fine when I leave scaling commented out but when I add it and then do a Matrix.Invert() on the created translation matrix the result is NaN ({NaN,NaN,NaN},{NaN,NaN,NaN},...) Can anyone tell me why this is happening please? Here's the code from the sample: // Build the block's transform Matrix blockTransform = Matrix.CreateTranslation(new Vector3(-blockOrigin, 0.0f)) * // Matrix.CreateScale(block.Scale) * would go here Matrix.CreateRotationZ(blocks[i].Rotation) * Matrix.CreateTranslation(new Vector3(blocks[i].Position, 0.0f)); public static bool IntersectPixels( Matrix transformA, int widthA, int heightA, Color[] dataA, Matrix transformB, int widthB, int heightB, Color[] dataB) { // Calculate a matrix which transforms from A's local space into // world space and then into B's local space Matrix transformAToB = transformA * Matrix.Invert(transformB); // When a point moves in A's local space, it moves in B's local space with a // fixed direction and distance proportional to the movement in A. // This algorithm steps through A one pixel at a time along A's X and Y axes // Calculate the analogous steps in B: Vector2 stepX = Vector2.TransformNormal(Vector2.UnitX, transformAToB); Vector2 stepY = Vector2.TransformNormal(Vector2.UnitY, transformAToB); // Calculate the top left corner of A in B's local space // This variable will be reused to keep track of the start of each row Vector2 yPosInB = Vector2.Transform(Vector2.Zero, transformAToB); // For each row of pixels in A for (int yA = 0; yA < heightA; yA++) { // Start at the beginning of the row Vector2 posInB = yPosInB; // For each pixel in this row for (int xA = 0; xA < widthA; xA++) { // Round to the nearest pixel int xB = (int)Math.Round(posInB.X); int yB = (int)Math.Round(posInB.Y); // If the pixel lies within the bounds of B if (0 <= xB && xB < widthB && 0 <= yB && yB < heightB) { // Get the colors of the overlapping pixels Color colorA = dataA[xA + yA * widthA]; Color colorB = dataB[xB + yB * widthB]; // If both pixels are not completely transparent, if (colorA.A != 0 && colorB.A != 0) { // then an intersection has been found return true; } } // Move to the next pixel in the row posInB += stepX; } // Move to the next row yPosInB += stepY; } // No intersection found return false; }

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• Duplicate ping response when running Ubuntu as virtual machine (VMWare)

  - by Stonerain

  I have the following setup: My router - 192.168.0.1 My host computer (Windows 7) - 192.168.0.3 And Ubuntu is running as virtual machine on the host. VMWare network settings is Bridged mode. I've modified Ubuntu network settings in /etc/netowrk/interfaces, set the following config: iface eth0 inet static address 192.168.0.220 netmask 255.255.255.0 network 192.168.0.0 broadcast 192.168.0.255 gateway 192.168.0.1 Internet works correctly, I can install packages. But it gets weird if I try to ping something I get this: PING belpak.by (193.232.248.80) 56(84) bytes of data. From 192.168.0.1 icmp_seq=1 Time to live exceeded From 192.168.0.1 icmp_seq=1 Time to live exceeded From 192.168.0.1 icmp_seq=1 Time to live exceeded From 192.168.0.1 icmp_seq=1 Time to live exceeded From 192.168.0.1 icmp_seq=1 Time to live exceeded 64 bytes from belhost.by (193.232.248.80): icmp_seq=1 ttl=250 time=17.0 ms 64 bytes from belhost.by (193.232.248.80): icmp_seq=1 ttl=249 time=17.0 ms (DUP! ) 64 bytes from belhost.by (193.232.248.80): icmp_seq=1 ttl=248 time=17.0 ms (DUP! ) 64 bytes from belhost.by (193.232.248.80): icmp_seq=1 ttl=247 time=17.0 ms (DUP! ) 64 bytes from belhost.by (193.232.248.80): icmp_seq=1 ttl=246 time=17.0 ms (DUP! ) ^CFrom 192.168.0.1 icmp_seq=2 Time to live exceeded --- belpak.by ping statistics --- 2 packets transmitted, 1 received, +4 duplicates, +6 errors, 50% packet loss, ti me 999ms rtt min/avg/max/mdev = 17.023/17.041/17.048/0.117 ms I think even more interesting are the results of pinging the router itself: stonerain@ubuntu:~$ ping 192.168.0.1 -c 1 PING 192.168.0.1 (192.168.0.1) 56(84) bytes of data. From 192.168.0.3: icmp_seq=1 Redirect Network(New nexthop: 192.168.0.1) 64 bytes from 192.168.0.1: icmp_seq=1 ttl=254 time=6.64 ms --- 192.168.0.1 ping statistics --- 1 packets transmitted, 1 received, 0% packet loss, time 0ms rtt min/avg/max/mdev = 6.644/6.644/6.644/0.000 ms But if I set -c 2: ... 64 bytes from 192.168.0.1: icmp_seq=1 ttl=252 time=13.5 ms (DUP!) 64 bytes from 192.168.0.1: icmp_seq=1 ttl=251 time=13.5 ms (DUP!) 64 bytes from 192.168.0.1: icmp_seq=1 ttl=254 time=13.5 ms (DUP!) 64 bytes from 192.168.0.1: icmp_seq=1 ttl=253 time=13.5 ms (DUP!) 64 bytes from 192.168.0.1: icmp_seq=1 ttl=252 time=13.5 ms (DUP!) 64 bytes from 192.168.0.1: icmp_seq=1 ttl=251 time=13.5 ms (DUP!) From 192.168.0.3: icmp_seq=2 Redirect Network(New nexthop: 192.168.0.1) 64 bytes from 192.168.0.1: icmp_seq=2 ttl=254 time=7.87 ms --- 192.168.0.1 ping statistics --- 2 packets transmitted, 2 received, +256 duplicates, 0% packet loss, time 1002ms rtt min/avg/max/mdev = 6.666/10.141/13.556/2.410 ms Pinging host machine on the other hand works absolutely correctly: no DUPs, no errors. What seems to be the problem and how can I fix it? Thank you.

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• What is the best way to implement collision detection using Bullet physics engine and a track generated from a curve?

  - by tigrou

  I am developing a small racing game were the track is generated from a curve. As said above, the track is generated, but not infinite. The track of one level could fit with no problem in memory and will contain a reasonably small amount of triangles. For collisions, I would like to use Bullet physics engine and know what is the best way to handle collisions with the track efficiently. NOTE : The track will be stored as a static rigid body (mass = 0). The player will be represented by a sphere shape for collisions. Here is some possibilities i have in mind : Create one rigid body, then, put all triangles of the track (except non collidable stuff) into it. Result : 1 body with many triangles (eg : 30000 triangles) Split the track into several sections (eg: 10 sections). Then, for each section, create a rigid body and put corresponding triangles in it. Result : small amount of bodies with relatively small amount of triangles (eg : 1500 triangles per section). Split the track into many sub-sections (eg : 1200 sections). Here one subsection = very small step when generating the curve. Again for each sub-section, create a body and put triangles in it. Result : many bodies with very small amount of triangles (eg : 20 triangles). Advantage : it could be possible to "extra data" to each of the subsection, that could be used when handling collisions. Same as 2, but only put sections N and N+1 in physics engine (where N = current section where the player is). When player reach section N+1, unload section N and load section N+2 and so on... Issue : harder to implement, problems if the player suddenly "jump" from one section to another (eg : player fly away from section N, and fall on section N + 4 that was underneath : no collision handled, player will fall into void ) Same as 4, but with many sub-sections. Issues : since subsections are very small there will be constantly new bodies added and removed to physics engine at runtime. Possibilities for player to accidently skip some sections and fall into the void are higher than 4.

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• C Minishell Command Expansion Printing Gibberish

  - by Optimus_Pwn

  I'm writing a unix minishell in C, and am at the point where I'm adding command expansion. What I mean by this is that I can nest commands in other commands, for example: $> echo hello $(echo world! ... $(echo and stuff)) hello world! ... and stuff I think I have it working mostly, however it isn't marking the end of the expanded string correctly, for example if I do: $> echo a $(echo b $(echo c)) a b c $> echo d $(echo e) d e c See it prints the c, even though I didn't ask it to. Here is my code: msh.c - http://pastebin.com/sd6DZYwB expand.c - http://pastebin.com/uLqvFGPw I have a more code, but there's a lot of it, and these are the parts that I'm having trouble with at the moment. I'll try to tell you the basic way I'm doing this. Main is in msh.c, here it gets a line of input from either the commandline or a shellfile, and then calls processline (char *line, int outFD, int waitFlag), where line is the line we just got, outFD is the file descriptor of the output file, and waitFlag tells us whether or not we should wait if we fork. When we call this from main we do it like this: processline (buffer, 1, 1); In processline, we allocate a new line: char expanded_line[EXPANDEDLEN]; We then call expand, in expand.c: expand(line, expanded_line, EXPANDEDLEN); In expand, we copy the characters literally from line to expanded_line until we find a $(, which then calls: static int expCmdOutput(char *orig, char *new, int *oldl_ind, int *newl_ind) orig is line, and new is expanded line. oldl_ind and newl_ind are the current positions in the line and expanded line, respectively. Then we pipe, and recursively call processline, passing it the nested command(for example, if we had "echo a $(echo b)", we would pass processline "echo b"). This is where I get confused, each time expand is called, is it allocating a new chunk of memory EXPANDEDLEN long? If so, this is bad because I'll run out of stack room really quickly(in the case of a hugely nested commandline input). In expand I insert a null character at the end of the expanded string, so why is it printing past it? If you guys need any more code, or explanations, just ask. Secondly, I put the code in pastebin because there's a ton of it, and in my experience people don't like it when I fill up several pages with code. Thanks.

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• Ray Picking Problems

  - by A Name I Haven't Decided On

  I've read so many answers on here about how to do Ray Picking, that I thought I had the idea of it down. But when I try to implement it in my game, I get garbage. I'm working with LWJGL. Here's the code: public static Ray getPick(int mouseX, int mouseY){ glPushMatrix(); //Setting up the Mouse Clip Vector4f mouseClip = new Vector4f((float)mouseX * 2 / 960f - 1, 1 - (float)mouseY * 2 / 640f ,0 ,1); //Loading Matrices FloatBuffer modMatrix = BufferUtils.createFloatBuffer(16); FloatBuffer projMatrix = BufferUtils.createFloatBuffer(16); glGetFloat(GL_MODELVIEW_MATRIX, modMatrix); glGetFloat(GL_PROJECTION_MATRIX, projMatrix); //Assigning Matrices Matrix4f proj = new Matrix4f(); Matrix4f model = new Matrix4f(); model.load(modMatrix); proj.load(projMatrix); //Multiplying the Projection Matrix by the Model View Matrix Matrix4f tempView = new Matrix4f(); Matrix4f.mul(proj, model, tempView); tempView.invert(); //Getting the Camera Position in World Space. The 4th Column of the Model View Matrix. model.invert(); Point cameraPos = new Point(model.m30, model.m31, model.m32); //Theoretically getting the vector the Picking Ray goes Vector4f rayVector = new Vector4f(); Matrix4f.transform(tempView, mouseClip, rayVector); rayVector.translate((float)-cameraPos.getX(),(float) -cameraPos.getY(),(float) -cameraPos.getZ(), 0f); rayVector.normalise(); glPopMatrix(); //This Basically Spits out a value that changes as the Camera moves. //When the Mouse moves, the values change around 0.001 points from screen edge to edge. System.out.format("Vector: %f %f %f%n", rayVector.x, rayVector.y, rayVector.z); //return new Ray(cameraPos, rayVector); return null; } I don't really know why this isn't working. I was hoping some more experienced eyes might be able to help me out. I can get the camera position like a champ, it's the vector the rays going in that I can't seem to get right. Thanks.

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