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IRQ Conflicts Causing Video Card and Boot Problems?

- by sanpatricio

tl;dr - I have 4 devices sharing 1 IRQ. Is this bad and how do I tell the BIOS to stop it? Background: I have an old Dell GX280 dual Pentium 4 that I (semi) resurrected last weekend with an installation of Ubuntu 12.04. Everything was going fine the first several hours until a problem that plagued me when WinXP was on that machine happened -- it froze. Completely froze. None of the myriad of ways I have found here on askubuntu helped me to regain control except a long-press of the power button to shut it off. Clearly, this wasn't a software/WinXP issue. After much googling, I found that hardware conflicts can often cause this sort of total lock-up and with all the odd blocks of yellow and flecks of color showing on my screen (both WinXP and Ubuntu) I figured my old GeForce 7600 was failing and causing me these odd issues. (A good canned-air dusting of the entire interior fixed the color fleck problem) Again, through much googling and numerous answers found on askubuntu, I somehow stumbled my way onto the lshw command. After going through it, line by line, I found that I have four devices sharing IRQ 16: eth0, wlan0, ide0 (DVD-RW), and my video card. In hindsight, I can recall weird instances of my Ethernet connection to another computer not working when I thought it should. I never full troubleshot those issues so it could be a coincidence. The other thing that has been plaguing me since installing Ubuntu (wasn't there during WinXP) has been periodic moments of my monitor getting no signal from Ubuntu during boot. The first couple days, it would disappear after the Dell boot screen and reappear at Ubuntu login. Now, it disappears after the Dell boot screen and doesn't return at all -- I have to hit F12 where I can load a safe mode version of Ubuntu and get more details like dmesg and lsdev. I also ran memtest86 overnight and woke up to zero errors, so failing RAM is out. Where do I go from here?

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What are all the components of a "Facebook App"?

- by pnongrata

I am a developer who has never personally partaken in social media (in any form) for reasons completely outside the scope of this question. I am "off the grid" (no Facebook, Twitter, etc accounts). I'm currently building a web app and would like the app to have a presence on Facebook, and possibly even "port" my app over as a Facebook app. My understanding of Facebook Apps is that they're just normal web apps that get <iframe>d into a Facebook page. The app is actually hosted on your server (not FB's servers). But this got me thinking: Don't Facebook Apps have "profile pages"? Is there anything developers can do to customize the behavior of their own profile pages? Do apps have the ability to do things like MySpace themes used to do (i.e., customize and interact with User profile pages, Groups, etc.)? Do Facebook Apps gain any sort of extra capabilities (inside of Facebook) that a normal web app would not have? It seems to me like if all a Facebook App is, is an iframed-web app, that it would still need to communicate with Facebook via its many APIs, just like a normal app would have to, right? If it's not possible to write an app that can customize the UI or behavior of user profiles and other pages, then how do games like "Farmville" interact with User profiles so that you see updates to profiles like "John Smith reached level 2 of Farmville"? Basically, I'm asking any battle-worn Facebook app developers if my understanding of Facebook Apps is correct, or if I'm missing anything big here. It's my understanding that for security reasons (obviously) Facebook doesn't allow apps to customize anything outside of the iframe it lives in. So if I want my app to appear like it's "interacting" with its Facebook users, it looks like I just need to publish stuff to the users' news feeds to try and encourage people to use my app (please correct me if I'm wrong here!). Thanks in advance for any corrections, clarifications, advice or suggestions!

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What are some ways to separate game logic from animations and the draw loop?

- by TMV

I have only previously made flash games, using MovieClips and such to separate out my animations from my game logic. Now I am getting into trying my hand at making a game for Android, but the game programming theory around separating these things still confuses me. I come from a background of developing non game web applications so I am versed in more MVC like patterns and am stuck in that mindset as I approach game programming. I want to do things like abstract my game by having, for example, a game board class that contains the data for a grid of tiles with instances of a tile class that each contain properties. I can give my draw loop access to this and have it draw the game board based on the properties of each tile on the game board, but I don't understand where exactly animation should go. As far as I can tell, animation sort of sits between the abstracted game logic (model) and the draw loop (view). With my MVC mindset, it's frustrating trying to decide where animation is actually supposed to go. It would have quite a bit of data associated with it like a model, but seemingly needs to be very closely coupled with the draw loop in order to have things like frame independent animation. How can I break out of this mindset and start thinking about patterns that make more sense for games?

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D3DXMatrixDecompose gives different quaternion than D3DXQuaternionRotationMatrix

- by Fraser

In trying to solve this problem, I tracked down the problem to the conversion of the rotation matrix to quaternion. In particular, consider the following matrix: -0.02099178 0.9997436 -0.008475631 0 0.995325 0.02009799 -0.09446743 0 0.09427284 0.01041905 0.9954919 0 0 0 0 1 SlimDX.Quaternion.RotationMatrix (which calls D3DXQuaternionRotationMatrix gives a different answer than SlimDX.Matrix.Decompose (which uses D3DXMatrixDecompose). The answers they give (after being normalized) are: X Y Z W Quaternion.RotationMatrix -0.05244324 0.05137424 0.002209336 0.9972991 Matrix.Decompose 0.6989997 0.7135442 -0.03674842 -0.03006023 Which are totally different (note the signs of X, Z, and W are different). Note that these aren't q/-q (two quaternions that represent the same rotation); they face completely different directions. I've noticed that with matrices for rotations very close to that one (successive frames in the animation) that the Matrix.Decompose version gives a solution that flips around wildly and occasionally goes into the desired position, while the Quaternion.RotationMatrix version gives solutions that are stable but go in the wrong direction. This is only for the right arm in my animation -- for the left arm, both functions give the correct solution, which is the same quaternion within error tolerances. This makes me think that there's some sort of numeric instability or weird stuff with signs going on. I tried implementing this and then this, but both gave me a completely incorrect solution (even for the matricies where the SlimDX ones were working correctly) -- maybe the rows and columns are flipped?

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3D physics engine for accurate collision handling on desktop/laptop computers (non-console)

- by Georges Oates Larsen

What are your suggestions for a physics engine that satisfies the following criteria? Capable of calculating collisions between multiple concave mesh-based colliders Handles many collisions going on at once (for instance one mesh being wedged between two others, which themselves may be wedged between two meshes) Does not allow for collider passthrough, even at high speeds. For instance, if I am applying force to a programmatically hinged object that makes it spin, I do not want it to pass through another rigidbody that it collides with while spinning. I have this problem using PhysX As implied before, reacts well to hinged objects, preferably has its own implementation of a hinge, but I am willing to program my own. The important part is that it has some sort of interface that guarantees accurate collision tracking even when dealing with these things Platform independent -- runs on mac as well as PC, also not tied down to specific graphics cards I think that's the best way to explain what I am looking for. Basically, I need SUPER reliable collisions. Something that can't be accomplished with a simple ray casting approach that sends a ray from the last position of the object to the current position (as this object may be potentially large and colliding with small objects via rotation) Bonus points for also including an OPEN SOURCE engine.

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Enforcing Constraints Upon Data Documents of Various Formats

- by Christopher Berman

This seems like the sort of problem that must have been solved elegantly long ago, but I haven't the foggiest how to google it and find it. Suppose you're maintaining a large legacy system, which has a large collection of data (tens of GB) of various formats, including XML and two different internal configuration formats. Suppose further that there are abstract rules governing the values these files may or may not contain. EXAMPLE: File A defines the raw, mathematical data pertaining to the aerodynamics of a car for consumption of the physics component of the system. File B contains certain values from File A in an easily accessible, XML hierarchy for consumption of a different component of the system. There exists, therefore, an abstract rule (or constraint) such that the values from File B must match the values from File A. This is probably the simplest constraint that can be specified, but in practice, the constraints between files can become very complicated indeed. What is the best method for managing these constraints between files of arbitrary formats, short of migrating it over to an RDBMS (which simply isn't feasible for the foreseeable future)? Has this problem been solved already? To be more specific, I would expect the solution to at least produce notifications of violated constraints; the solution need not resolve the constraints. ============================== Sample file structures File A (JeepWrangler2011.emv): MODEL JeepWrangler2011 { EsotericMathValueX 11.1 EsotericMathValueY 22.2 EsotericMathValueZ 33.3 } File B (JeepWrangler2011.xml): <model name="JeepWrangler2011">  <modelExtent x="11.1" y="22.2" z="33.3"/> [...] </model>

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Legacy Code Retreat Questions

- by MarkPearl

I recently heard of the concept of a Legacy Code Retreat. Since I have attended and helped facilitate some normal Code Retreats I thought it might be interesting in trying a Legacy Code Retreat, but I have a few questions on how a legacy CR differs from a normal one. If anyone has attended a Legacy CR and has some suggestions on how best to host these event’s please leave a comment on what has worked for you in the past or if you have any answers to my questions below… Should you restrict the languages that people can do the sessions in? In the normal CR’s I have been involved in the past we have had people attend and code in their programming language of choice. A normal CR lends itself to this because each session starts with no code. With a legacy CR each session seems to start with an existing code base. Is there some sort of limitation on the languages that people can work in during the sessions? If not, how do you give them a base to start from? What happens as the beginning of each session? In the normal CR that I have attended each session would have a constraint set on it – i.e. no if statements used, no primitives, etc. With a legacy CR it seems more like patterns for refactoring are learned. Does the facilitator explain the pattern used before the session starts or are they just given a code base to start from and an objective to achieve

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How to decide if I should take a profit sharing offer or insist on hard cash

- by Icode4food

I am currently the sole developer at the very beginning stages of what I think could be a successful startup. My question is simply how to go about determining if I am interested in accepting a permanent stock in the enterprise or if I should insist on hard cash. This startup is seeking venture capital and it is looking likely that they will get something, I don't know how much. I know very little about the business plan or financial operations at all. The founders have experience with other startup type devours that have been successful. From a business perspective I have a reasonable amount of confidence in them. However, I have never met them face to face. They have offered me a partnership in the project but I'm fairly confident that I don't want to do that. I have done some work for them and they really like me so I'm not to afraid of loosing the position all together. I am a young developer with no experience with this sort of thing and need some experience to point me in the right direction. How to I begin to evaluate how much stock or what percentage of the profit should I ask for? Any suggestions at all would be appreciated! P.S. Any suggestions for better tags?

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How do I get 1366x768 resolution on 12.04?

- by Megan

I am on an HP Envy 14, and the proper resolution that I should be using is 1366x768. This is not an option and I am stuck on 1024x768. I am using Linux 12.04. lspci | grep VGA: 00:02.0 VGA compatible controller: Intel Corporation Core Processor Integrated Graphics Controller (rev 02) 01:00.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI Madison [Radeon HD 5000M Series] I've tried to add the resolution as a mode in xorg.conf but that does not work. Please any help would be appreciated. I'm new to Linux and just got my dual boot working but this resolution issue is killing me. Edit1 I just tried using the xrandr command: xrandr --newmode "1368x768_60.00" 85.25 1368 1440 1576 1784 768 771 781 798 -hsync +vsync But I get an error: xrandr: Failed to get size of gamma for output default Edit2 lsmod returns the following: Module Size Used by vesafb 13844 1 rfcomm 47604 12 bnep 18281 2 parport_pc 32866 0 ppdev 17113 0 snd_hda_codec_hdmi 32474 1 arc4 12529 2 joydev 17693 0 hid_logitech_dj 18594 0 i915 472941 5 uvcvideo 72627 0 usbhid 47199 1 hid_logitech_dj hid 99559 2 hid_logitech_dj,usbhid psmouse 87692 0 iwlwifi 332525 0 mac80211 506816 1 iwlwifi videodev 98259 1 uvcvideo snd_hda_codec_idt 70795 1 mei 41616 0 btusb 18288 2 v4l2_compat_ioctl32 17128 1 videodev hp_accel 25976 0 lis3lv02d 19876 1 hp_accel hp_wmi 18092 0 sparse_keymap 13890 1 hp_wmi input_polldev 13896 1 lis3lv02d drm_kms_helper 46978 1 i915 drm 242038 2 i915,drm_kms_helper i2c_algo_bit 13423 1 i915 serio_raw 13211 0 snd_hda_intel 33773 5 snd_hda_codec 127706 3 snd_hda_codec_hdmi,snd_hda_codec_idt,snd_hda_intel snd_hwdep 13668 1 snd_hda_codec bluetooth 180104 23 rfcomm,bnep,btusb cfg80211 205544 2 iwlwifi,mac80211 snd_pcm 97188 3 snd_hda_codec_hdmi,snd_hda_intel,snd_hda_codec mac_hid 13253 0 snd_seq_midi 13324 0 snd_rawmidi 30748 1 snd_seq_midi snd_seq_midi_event 14899 1 snd_seq_midi snd_seq 61896 2 snd_seq_midi,snd_seq_midi_event fglrx 3263886 0 snd_timer 29990 2 snd_pcm,snd_seq snd_seq_device 14540 3 snd_seq_midi,snd_rawmidi,snd_seq snd 78855 20 snd_hda_codec_hdmi,snd_hda_codec_idt,snd_hda_intel,snd_hda_codec,snd_hwdep,snd_pcm,snd_ra wmidi,snd_seq,snd_timer,snd_seq_device wmi 19256 1 hp_wmi video 19596 1 i915 intel_ips 18174 0 soundcore 15091 1 snd snd_page_alloc 18529 2 snd_hda_intel,snd_pcm lp 17799 0 parport 46562 3 parport_pc,ppdev,lp r8169 62099 0 I have installed ATI/AMD proprietary FGLRX graphics driver. But there is another one called ATI/AMD proprietary FGLRX graphics driver (post-release updates) which I have trouble installing because it gives me an error and tells me to look at some sort of jockey log.

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Create option to load Ubuntu or Windows 7 at start-up

- by AXK

We have a new Dell Optiplex 790 desktop with Windows 7 and just installed Ubuntu 12.04 on it using a USB stick that was configured as a boot drive. We created a new partition for Ubuntu during installation using the partition editor that comes up during installation. Everything seems to have gone fine with the installation except that, unexpectedly, there is no option to boot up Ubuntu when the computer is started. We just start the computer and Windows starts up with no option to ever start Ubuntu. The only way we have gotten Ubuntu to start is by putting the USB stick used for installation back into the computer and having the computer boot from it. Then GRUB shows up and the Ubuntu OS that we installed starts up (rather than the live-CD version on the USB stick). Previous times we have installed Ubuntu, GRUB shows up when we start the computer and we can choose among the various OSes installed. Can anyone suggest what to do? We want to have the option to launch either Windows 7 or Ubuntu 12.04 when we start the computer, with the default being Windows 7. Right now there is no option and Windows 7 just starts the way it did before we installed Ubuntu. Note that if we hit F1 soon after starting the computer, we get some sort of Windows bootloader (not sure of exact name) but there is no option for Ubuntu; just Windows 7. Also note that if we hit the shift key soon after starting the computer, as some help pages have suggested, nothing happens (Windows 7 is loaded as usual). Thanks in advance!

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Why is CS never a topic of conversation of the layman? [closed]

- by hydroparadise

Granted, every profession has it's technicalities. If you are an MD, you better know the anatomy of the human body, and if you are astronomer, you better know your calculus. Yet, you don't have to know these more advance topics to know that smoking might give you lung cancer because of carcinogens or the moon revolves around the earth because of gravity (thank you Discovery Channel). There's sort of a common knowledge (at least in more developed countries) of these more advanced topics. With that said, why are things like recursive descent parsing, BNF, or Turing machines hardly ever mentioned outsided 3000 or 4000 level classes in a university setting or between colleagues? Even back in my days before college in my pursuit of knowledge on how computers work, these very important topics (IMHO) never seem to get the light of day. Many different sources and sites go into "What is a processor?" or "What is RAM?", or "What is an OS?". You might get lucky and discover something about programming languages and how they play a role in how applications are created, but nothing about the tools for creating the language itself. To extend this idea, Dennis Ritchie died shortly after Steve Jobs, yet Dennis Ritchie got very little press compared to Steve Jobs. So, the heart of my question: Does the public in general not care to hear about computer science topics that make the technology in their lives work, or does the computer science community not lend itself to the general public to close the knowledge gap? Am I wrong to think the general public has the same thirst for knowledge on how things work as I do? Please consider the question carefully before answering or vote closing please.

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Microsoft WPC 12–Predictions

- by D'Arcy Lussier

Let me start by saying I have absolutely no inside knowledge, neither through the MVP program or any other means, that is fuelling what I’m about to write. This is entirely conjecture fuelled by speculation and too much Soporro beer at a fantastic Japanese restaurant tonight. Still, I present to you… D’Arcy’s Worldwide Partner Conference 2012 Predictions!!! So what can we expect to be announced at this year’s WPC? Much more than last year I’m hoping! Last year was sort of encouraging the troops to carry on with the Windows 7 messaging even with Windows 8 looming in the distance. It also showed Microsoft’s slant towards Private Cloud in addition to Azure. This year, we’re going to see a shift to a battle cry – Windows 8 is Coming, Windows 8 is Coming! I expect we’re going to hear an RTM date for Windows 8 from Steve Ballmer tomorrow, in addition to dates surrounding Windows Server 2012. We’ll also hear some announcement around Windows Phone 8, but I’m not really sure what – that whole piece is still quite muddy; are we going to actually *see* Windows Phone 8 devices this week? That would be great, but I imagine those types of announcements might be left for Build. Speaking of Build, I’m expecting an announcement on a date for a Build conference this Fall, probably late October. If any announcements are going to be made around Office 15, the schedule isn’t hinting at it. In fact, other than Office 365 there’s not much mention of Office in the conference sessions – either a red herring, or telling that Microsoft has another announcement coming later. The tagline of the conference is “A New Era. Together.” It’s obvious Microsoft is wanting to leverage WPC to rally their partners to carry the Windows 8 banner into the field of battle this fall when it ships. D

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C++ and SDL Trouble Creating a STL Vector of a Game Object

- by Jackson Blades

I am trying to create a Space Invaders clone using C++ and SDL. The problem I am having is in trying to create Waves of Enemies. I am trying to model this by making my Waves a vector of 8 Enemy objects. My Enemy constructor takes two arguments, an x and y offset. My Wave constructor also takes two arguments, an x and y offset. What I am trying to do is have my Wave constructor initialize a vector of Enemies, and have each enemy given a different x offset so that they are spaced out appropriately. Enemy::Enemy(int x, int y) { box.x = x; box.y = y; box.w = ENEMY_WIDTH; box.h = ENEMY_HEIGHT; xVel = ENEMY_WIDTH / 2; } Wave::Wave(int x, int y) { box.x = x; box.y = y; box.w = WAVE_WIDTH; box.y = WAVE_HEIGHT; xVel = (-1)*ENEMY_WIDTH; yVel = 0; std::vector<Enemy> enemyWave; for (int i = 0; i < enemyWave.size(); i++) { Enemy temp(box.x + ((ENEMY_WIDTH + 16) * i), box.y); enemyWave.push_back(temp); } } I guess what I am asking is if there is a cleaner, more elegant way to do this sort of initialization with vectors, or if this is right at all. Any help is greatly appreciated.

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Can i change the order of these OpenGL / Win32 calls?

- by Adam Naylor

I've been adapting the NeHe ogl/win32 code to be more object orientated and I don't like the way some of the calls are structured. The example has the following pseudo structure: Register window class Change display settings with a DEVMODE Adjust window rect Create window Get DC Find closest matching pixel format Set the pixel format to closest match Create rendering context Make that context current Show the window Set it to foreground Set it to having focus Resize the GL scene Init GL The points in bold are what I want to move into a rendering class (the rest are what I see being pure win32 calls) but I'm not sure if I can call them after the win32 calls. Essentially what I'm aiming for is to encapsulate the Win32 calls into a Platform::Initiate() type method and the rest into a sort of Renderer::Initiate() method. So my question essentially boils down to: "Would OpenGL allow these methods to be called in this order?" Register window class Adjust window rect Create window Get DC Show the window Set it to foreground Set it to having focus Change display settings with a DEVMODE Find closest matching pixel format Set the pixel format to closest match Create rendering context Make that context current Resize the GL scene Init GL (obviously passing through the appropriate window handles and device contexts.) Thanks in advance.

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Cannot view, use, or open CDs or DVDs in Ubuntu 12.04

- by user67592

I am fairly new to Ubuntu 12.04 and I have encountered a rather irritating problem. Whenever I insert a CD or DVD (whether it have data, music, movies, or nothing at all), nothing pops up saying "you have inserted a CD", "play with Rhythmbox?" etc. It doesn't show the CD in the launcher/dock or anything of the sort. This is especially peculiar because not only do I have a standard IDE built-in optical drive, but I have an external USB optical drive. Neither work. In addition, whenever I go to "Computer///" and I click (double click, right click, or even left click) on "CD/DVD Drive" nothing happens, when I right click and select "Open" nothing happens either [for either of the two drives (both are listed in Computer///)] And if I insert a blank disk and go to a disk burning program such as Brasero, and try to burn to the drive it detects no CDs or DVDs of any kind. I'm rather stumped and can't seem to find a question similar to this. :( Thanks for all your help in advance!! :) ~Preston Output of sudo lshw *-cdrom description: DVD-RAM writer product: CD/DVDW TS-H652M vendor: TSSTcorp physical id: 0.0.0 bus info: scsi@5:0.0.0 logical name: /dev/cdrom logical name: /dev/cdrw logical name: /dev/dvd logical name: /dev/dvdrw logical name: /dev/sr0 version: 0414 capabilities: removable audio cd-r cd-rw dvd dvd-r dvd-ram configuration: ansiversion=5 status=nodisc *-cdrom description: DVD reader product: DVD Writer 300n vendor: HP physical id: 0.0.0 bus info: scsi@4:0.0.0 logical name: /dev/cdrom2 logical name: /dev/cdrw2 logical name: /dev/dvd2 logical name: /dev/sr1 version: 1.25 serial: [ capabilities: removable audio cd-r cd-rw dvd configuration: status=nodisc

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What is the value of workflow tools?

- by user16549

I'm new to Workflow developement, and I don't think I'm really getting the "big picture". Or perhaps to put it differently, these tools don't currently "click" in my head. So it seems that companies like to create business drawings to describe processes, and at some point someone decided that they could use a state machine like program to actually control processes from a line and boxes like diagram. Ten years later, these tools are huge, extremely complicated (my company is currently playing around with WebSphere, and I've attended some of the training, its a monster, even the so called "minimalist" versions of these workflow tools like Activiti are huge and complicated although not nearly as complicated as the beast that is WebSphere afaict). What is the great benefit in doing it this way? I can kind of understand the simple lines and boxes diagrams being useful, but these things, as far as I can tell, are visual programming languages at this point, complete with conditionals and loops. Programmers here appear to be doing a significant amount of work in the lines and boxes layer, which to me just looks like a really crappy, really basic visual programming language. If you're going to go that far, why not just use some sort of scripting language? Have people thrown the baby out with the bathwater on this? Has the lines and boxes thing been taken to an absurd level, or am I just not understanding the value in all this? I'd really like to see arguments in defense of this by people that have worked with this technology and understand why its useful. I don't see the value in it, but I recognize that I'm new to this as well and may not quite get it yet.

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Would form keys reduce the amount of spam we receive?

- by David Wilkins

I work for a company that has an online store, and we constantly have to deal with a lot of spam product reviews, and bogus customer accounts. These are all created by automated systems and are more of a nuisance than anything. What I am thinking of (in lieu of captcha, which can be broken) is adding a sort of form key solution to all relevant forms. I know for certain some of the spammers are using XRumer, and I know they seldom request a page before sending us the form data (Is this the definition of CSRF?) so I would think that tying a key to each requested form would at least stem the tide. I also know the spammers are lazy and don't check their work, or they would see that we have never posted a spam review, and they have never gained any revenue from our site. Would this succeed in significantly reducing the volume of spam product reviews and customer account creations we are seeing? EDIT: To clarify what I mean by "Form Keys": I am referring to creating a unique identifier (or "key") that will be used as an invisible, static form field. This key will also be stored either in the database (relative to the user session) or in a cookie variable. When the form's target gets a request, the key must be validated for the form's data to be processed. Those pesky bots won't have the key because they don't load the javascript that generates the form (they just send a blind request to the target) and even if they did load the javascript once, they'd only have one valid key, and I'm not sure they even use cookies.

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Is ZeroMQ a good choice to make a Python app and a C# managed assembly work together?

- by Alex Bausk

I have a task that involves talking to a .NET-based API (namely AutoCAD) to retrieve data, send commands, and react to events. I want to separate the API operations and the proper program logic (largely already implemented in Python) by using natural tools for both: a C# DLL for the former and a Python app for the latter. To connect these two pieces, I began exchanging JSON in ZeroMQ messages. I'm at early development stages but having recently discovered that ZeroMQ does not guarantee message delivery/order, I have reservations about whether this is a feasible way to go. Right now my app is a very basic REQ/REP pair and I plan to handle reacting to events and executing different commands by adding some sort of 'recipient-function' field to my message format. The reason that I want to use ZMQ is that I might be able to scale the software into a larger, multi-user, distributed solution sometime. I am a lay programmer so I would ask for your advice about this architecture. Should I just go ahead with it and plan to deal with message reliability/ordering when problems appear? Should I consider developing some kind of a REST wrapper around ZMQ?

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How do I fix a terrible system error on ubuntu 12.04

- by Anonymous

I don't know what happened, but one day my computer had some sort of a system error and could no longer update itself. The software center will not open, it will begin to initialize and then a message pops up saying theres a system error and needs to shut down the software center. Then another box pops up after I go to report it saying it was unable to identify source or package name. I also can't extract a zipped folder to anything, or reinstall Ubuntu from a USB boot drive anymore, it keeps telling me my my computer isn't compatible when I know for a fact it is, because thats how I got Ubuntu on here in the first place. the only thing I know about this error is that a message popped up after I went to check for updates saying to report the problem and include this message in the report: 'E:malformed line 56 in source list /etc/apt/sources.list (dist parse)' it also called it a bug. I just want to know how to either get rid of the bug completely or find some way to be able to reinstall Ubuntu again. I know it's not a lot of information, but It's all I can give. Sorry.

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What's the best way to move cars along roads

- by David Thielen

I am implementing car movement game (sort-of like Locomotion). So 60 times a second I have to advance the movement of each car. The problem is I have to look ahead to see if there is a slower car, stop sign, or red light ahead. And then slow down appropiately. I also want to have the cars take time to go from stopped to full speed and again to slow down. I'm not implementing full-blown physics, but just a tick by tick speed up/slow down as that provides most of the realism to match what people expect to see. The best I've come up with is to walk out the full distance the car would travel of it was slowing to a stop and see if anywhere along that path it needed to slow down or stop. And then move it forward appropiately. I am moving the cars 60 times a second so I need this to be fast. And walking out that whole path each tick strikes me as processor intensive. What's the best way to do this?

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Rewrite img and link paths with htaccess and serve the file from rewritten path?

- by frequent

I have a static mockup page, which I want to "customize" by switching a variable used in image-src and link-href attributes. Paths will look like this: <img src="/some/where/VARIABLE/img/1.jpg" alt="" /> <link rel="some" href="/some/where/VARIABLE/stuff/foo.bar" /> I'm setting a cookie with the VARIABLE value on the preceding page and now want to modfiy the paths accordingly by replacing VARIABLE with the cookie value. I'm a htaccess newbie. This is what I have (doesn't work): <IfModule mod_rewrite.c> # get cookie value cookie RewriteCond %{HTTP_COOKIE} client=([^;]*) # rewrite/redirect to correct file RewriteRule ^/VARIABLE/(.+)$ /%1/$1 [L] </IfModule> So I thought my first line gets the cookie value and stores this in %1. And on the second line I'm filtering VARIABLE, replace it with the cookie value and whatever comes after VARIABLE in $1. Thanks for sheeding some light on what I'm doing, doing wrong and if I can do this at all using htaccess. EDIT: I'm sort of halfway through, but it's still not working... Mabye someone can apply the finishing touches: <IfModule mod_rewrite.c> # check for client cookie RewriteCond %{HTTP_COOKIE} (?:^|;\s*)client=([^;]*) # check if an image was requested RewriteCond %{REQUEST_FILENAME} \.(jpe?g|gif|bmp|png)$ # exclude these folders RewriteCond %{REQUEST_URI} !some/members/logos # grab everything before the variable folder and everything afterwards # replace this with first bracket/cookie_value/second bracket RewriteRule (^.+)/VARIABLE/(.+)$ $1/%1/$2 [L] </IfModule> Still can't get it to work, but I think this is the correct way of doing it. Thanks for help!

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Queueing up character actions

- by TheBroodian

I'm developing a 2D platformer with action-fighter elements. Currently things are working relatively smoothly but I'm having difficulty sorting something out. For the time, keeping my character's states and actions separated and preventing them from stepping on each others' toes is working out well and properly, but I would like to add a feature to my character to get him to behave a little bit more fluidly for the player. At the moment, he has numerous attacks and abilities that he can execute, all of them being executed with button presses. Here lies the problem: Being as everything is executed through button presses, while an action is in progress I flag the game to disregard further button presses until the action has completed. Therefore, consecutive actions cannot be performed until after the previous action has completed entirely. In runtime this behavior feels very icky, and very ungamelike. In games that rest most memorably at the forefront of my mind the player is able to execute button commands during the process of actions, and at the end of the current action, the following action is executed (seems like some sort of a queue system or something) Can anybody offer any guidance with this?

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Serializing network messages

- by mtsvetkov

I am writing a network wrapper around boost::asio and was wondering what is a good and simple way to serialize my messages. I have a message factory which can take care of dispatching the data to the correct builder, but I want to know if there are any established solutions for getting the binary data on the sender side and consequently passing the data for deserialization on the receiver end. Some options I've explored are: passing a pointer to a char[] to the serialize/deserialize functions (for serialize to write to, and deserialize to read from), but it's difficult to enforce buffer size this way; building on that, I decided to have the serialize function return a boost::asio::mutable_buffer, however ownership of the memory gets blurred between multiple classes, as the network wrapper needs to clean up the memory allocated by the message builder. I have also seen solutions involving streambuf's and stringstream's, but manipulating binary data in terms of its string representation is something I want to avoid. Is there some sort of binary stream I can use instead? What I am looking for is a solution (preferrably using boost libs) that lets the message builder dictate the amount of memory allocated during serialization and what that would look like in terms of passing the data around between the wrapper and message factory/message builders. PS. Messages contain almost exclusively built-in types and PODs and form a shallow but wide hierarchy for the sake of going through a factory. Note: a link to examples of using boost::serialization for something like this would be appreciated as I'm having difficulties figuring out the relation between it and buffers.

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Dedicated Servers: Is one better then two for LAMP pseudo HA setup? [closed]

- by bikedorkseattle

Possible Duplicate: How to find web hosting that meets my requirements? I know there are zillions of commentary about hosting out there, but I haven't read much about this. Our current well known host is having too many problems, the hardware we are on it subpar, and I'm ready to leave. A day of downtime can cost as much as our monthly hosting bill. A month of bad performance is just killing us right now, user and google wise. I'm wondering about running two dedicated boxes for LAMP, one running as the primary Nginx/Apache (proxy pass), and the other as the MySQL box. Running a single box scares the bejesus out of me because who knows how long it will take anyone to fix a raid card or whatever. The idea is to set this up using some sort of failover system using pacemaker and heartbeat. If one server goes down the other can take over for the other running both web and db. There are some good articles over at Linode about this. I have a few DBs that are 1GB+ and would like to load them into memory. Because of this, I'm shying away from a Linode HA setup because for the price I could do it with two dedicated like I described. Am I mad or an idiot? What are people out there doing for pseodu high availability good performance setups under $400/month? I'm a webmaster; I do a lot of things none of it that well :)

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How to handle the different frame rate on different devices?

- by Fenwick

I am not quite sure how frame per second works on a web page. I have a Canvas game that involves in moving an image from point A to B, and measuring the time elapsed. The code can be as simple as: var timeStamp = Date.now(); function update(){ obj.y += obj.speed; text = "Time: "+ (Date.now() - timeStamp) + "ms"; } The function update() is called every frame. The problem is that the time elapsed is different from device to device. It is pretty short on my PC, but get longer on my iPad, and is much longer on my cell phone. I thought it is because the FPS is smaller on mobile devices, so instead of calling update() every frame, I call it every 1ms by using a setInterval. But this does not solve the problem. In my understanding, the function for setInterval is invoked based on the increment in system time, other than frame rate, so it should fix the problem. Am I missing anything here? If the setInterval function is called based on FPS, is there any way to get around with the FPS difference across devices? On a side note, I have sort of a "water simulator" on the same canvas. It involves in redrawing about 60 objects which can be 600x600 pixels for every frame, so it could be a frame rate killer. I am using Phaser.js but not really using much of its functionalities, if that helps.

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