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  • Flickering problem with world matrix

    - by gnomgrol
    I do have a pretty wierd problem today. As soon as I try to change my translation- or rotationmatrix for an object to something else than (0,0,0), the object starts to flicker (scaling works fine). It rapid and randomly switches between the spot it should be in and a crippled something. I first thought that the problem would be z-fighting, but now Im pretty sure it isn't. I have now clue at all what it could be, here are two screenshots of the two states the plant is switching between. I already used PIX, but could find anything of use (Im not a very good debugger anyway) I would appreciate any help, thanks a lot! Important code: D3DXMatrixIdentity(&World); D3DXVECTOR3 rotaxisX = D3DXVECTOR3(1.0f, 0.0f, 0.0f); D3DXVECTOR3 rotaxisY = D3DXVECTOR3(0.0f, 1.0f, 0.0f); D3DXVECTOR3 rotaxisZ = D3DXVECTOR3(0.0f, 0.0f, 1.0f); D3DXMATRIX temprot1, temprot2, temprot3; D3DXMatrixRotationAxis(&temprot1, &rotaxisX, 0); D3DXMatrixRotationAxis(&temprot2, &rotaxisY, 0); D3DXMatrixRotationAxis(&temprot3, &rotaxisZ, 0); Rotation = temprot1 *temprot2 * temprot3; D3DXMatrixTranslation(&Translation, 0.0f, 10.0f, 0.0f); D3DXMatrixScaling(&Scale, 0.02f, 0.02f, 0.02f); //Set objs world space using the transformations World = Translation * Rotation * Scale; shader: cbuffer cbPerObject { matrix worldMatrix; matrix viewMatrix; matrix projectionMatrix; }; // Change the position vector to be 4 units for proper matrix calculations. input.position.w = 1.0f; // Calculate the position of the vertex against the world, view, and projection matrices. output.position = mul(input.position, worldMatrix); output.position = mul(output.position, viewMatrix); output.position = mul(output.position, projectionMatrix);

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  • Example of DOD design

    - by Jeffrey
    I can't seem to find a nice explanation of the Data Oriented Design for a generic zombie game (it's just an example, pretty common example). Could you make an example of the Data Oriented Design on creating a generic zombie class? Is the following good? Zombie list class: class ZombieList { GLuint vbo; // generic zombie vertex model std::vector<color>; // object default color std::vector<texture>; // objects textures std::vector<vector3D>; // objects positions public: unsigned int create(); // return object id void move(unsigned int objId, vector3D offset); void rotate(unsigned int objId, float angle); void setColor(unsigned int objId, color c); void setPosition(unsigned int objId, color c); void setTexture(unsigned int, unsigned int); ... void update(Player*); // move towards player, attack if near } Example: Player p; Zombielist zl; unsigned int first = zl.create(); zl.setPosition(first, vector3D(50, 50)); zl.setTexture(first, texture("zombie1.png")); ... while (running) { // main loop ... zl.update(&p); zl.draw(); // draw every zombie } Or would creating a generic World container that contains every action from bite(zombieId, playerId) to moveTo(playerId, vector) to createPlayer() to shoot(playerId, vector) to face(radians)/face(vector); and contains: std::vector<zombie> std::vector<player> ... std::vector<mapchunk> ... std::vector<vbobufferid> player_run_animation; ... be a good example? Whats the proper way to organize a game with DOD?

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  • How to avoid to be employed by companies which are candidates to DailyWTF stories?

    - by MainMa
    I'm reading The Daily WTF archives and especially those stories about IT-related companies which have a completely wrong approach of software development, the job of a developer, etc. Some stories are totally horrible: a company don't have a local network for security reasons, another one has a source control server which can only be accessed by the manager, etc. Add to it all those stories about managers who don't know anything about their work and make stupid decisions without listening to anybody. The thing is that I don't see how to know if you will be employed by such company during an interview. Of course, sometimes, an interviewer tells weird things which gives you an idea that something goes very wrong with the company (in my case, the last manager said I should work 100% of my time through Remote Desktop, connected to on an old and slooooow machine, because "it avoids several people to modify the same source code"; maybe I should explain him what SVN is). But in most cases, you will be unable to get enough information during the interview to get the exact image of a company. So how to avoid being employed by this sort of companies? I thought about asking to see some documents like documentation guide or code style guidelines. The problem is that I live in France, and here, most of the companies don't have those documents at all, and in the rare cases where those documents exist, they are outdated, poorly written, never used, or do force you to make things that don't make any sense. I also thought about asking to see how programmers actually work. But seeing that they have dual screens or "late-modern-artsy-fartsy furnishings" doesn't mean that they don't have people making weird decisions, making it impossible to work there. Have you been in such situations? What have you tried? Have it worked?

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  • Installing latest version of R-base

    - by Student
    I have been unsuccessfully trying to install the latest version (2.15.2) of r-base. Apparently, R package "Rcpp" would not install for R version 2.14.1 - the version that installs for me. I am not sure what/how/where to change my installation attempts which appear below. Please note that I am using ubuntu-12.04.1-server-i386. (1) ------------ The current installed version is R version 2.14.1 (2011-12-22) sudo apt-get install r-base Reading package lists... Done Building dependency tree Reading state information... Done r-base is already the newest version. (2) ------------ Including version information doesn't help: sudo apt-get install r-base=2.15.1-5ubuntu1 Reading package lists... Done Building dependency tree Reading state information... Done E: Version '2.15.1-5ubuntu1' for 'r-base' was not found (3) ------------- Changes based on CRAN Ubuntu instructions http://cran.r-project.org/bin/linux/ubuntu/README 3.1: Added to /etc/apt/sources.list deb http://lib.stat.cmu.edu/R/CRAN/bin/linux/ubuntu quantal/ 3.2: sudo apt-get update 3.3: sudo apt-get install r-base Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: r-base : Depends: r-base-core (= 2.15.2-1quantal2) but it is not going to be installed Depends: r-recommended (= 2.15.2-1quantal2) but it is not going to be installed Recommends: r-base-html but it is not going to be installed E: Unable to correct problems, you have held broken packages.

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  • Versioning APIs

    - by Sharon
    Suppose that you have a large project supported by an API base. The project also ships a public API that end(ish) users can use. Sometimes you need to make changes to the API base that supports your project. For example, you need to add a feature that needs an API change, a new method, or requires altering of one of the objects, or the format of one of those objects, passed to or from the API. Assuming that you are also using these objects in your public API, the public objects will also change any time you do this, which is undesirable as your clients may rely on the API objects remaining identical for their parsing code to work. (cough C++ WSDL clients...) So one potential solution is to version the API. But when we say "version" the API, it sounds like this also must mean to version the API objects as well as well as providing duplicate method calls for each changed method signature. So I would then have a plain old clr object for each version of my api, which again seems undesirable. And even if I do this, I surely won't be building each object from scratch as that would end up with vast amounts of duplicated code. Rather, the API is likely to extend the private objects we are using for our base API, but then we run into the same problem because added properties would also be available in the public API when they are not supposed to be. So what is some sanity that is usually applied to this situation? I know many public services such as Git for Windows maintains a versioned API, but I'm having trouble imagining an architecture that supports this without vast amounts of duplicate code covering the various versioned methods and input/output objects. I'm aware that processes such as semantic versioning attempt to put some sanity on when public API breaks should occur. The problem is more that it seems like many or most changes require breaking the public API if the objects aren't more separated, but I don't see a good way to do that without duplicating code.

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  • Interaction using Kinect in XNA

    - by Sweta Dwivedi
    So i have written a program to play a sound file when ever my RightHand.Joint touches the 3D model . . It goes like this . . even though the code works somehow but not very accurate . . for example it will play the sound when my hand is slightly under my 3D object not exactly on my 3D object . How do i make it more accurate? here is the code . . (HandX & HandY is the values coming from the Skeleton data RightHand.Joint.X etc) and also this calculation doesnt work with Animated Sprites..which i need to do foreach (_3DModel s in Solar) { float x = (float)Math.Floor(((handX * 0.5f) + 0.5f) * (resolution.X)); float y = (float)Math.Floor(((handY * -0.5f) + 0.5f) * (resolution.Y)); float z = (float)Math.Floor((handZ) / 4 * 20000); if (Math.Sqrt(Math.Pow(x - s.modelPosition.X, 2) + Math.Pow(y - s.modelPosition.Y, 2)) < 15) { //Exit(); PlaySound("hyperspace_activate"); Console.WriteLine("1" + "handx:" + x + "," + " " + "modelPos.X:" + s.modelPosition.X + "," + " " + "handY:" + y + "modelPos.Y:" + s.modelPosition.Y); } else { Console.WriteLine("2" + "handx:" + x + "," + " " + "modelPos.X:" + s.modelPosition.X + "," + " " + "handY:" + y + "modelPos.Y:" + s.modelPosition.Y); } }

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  • Low Graphics and laggy screen after update to 13.10 from 13.04

    - by Wh0RU
    After updating from 13.04 to 13.10 many of 3D unity stuff has stopped working, I am suing Samsung Series 3 (NP350V5X) Laptop which has Switchable Intel and AMD Radeon HD 7670M GFX. xserver-xorg-video-ati does works but NO 3D support and graphics are very low. [I am currently using this] fglrx & fglrx-updates shows blank screen after Login. Intel Graphic Install doesn't work either (dependency error) Output of $ sudo lshw -c video *-display description: VGA compatible controller product: Thames [Radeon HD 7500M/7600M Series] vendor: Advanced Micro Devices, Inc. [AMD/ATI] physical id: 0 bus info: pci@0000:01:00.0 version: 00 width: 64 bits clock: 33MHz capabilities: pm pciexpress msi vga_controller bus_master cap_list rom configuration: driver=radeon latency=0 resources: irq:45 memory:e0000000-efffffff memory:c0120000-c013ffff ioport:3000(size=256) memory:c0100000-c011ffff *-display description: VGA compatible controller product: 3rd Gen Core processor Graphics Controller vendor: Intel Corporation physical id: 2 bus info: pci@0000:00:02.0 version: 09 width: 64 bits clock: 33MHz capabilities: msi pm vga_controller bus_master cap_list rom configuration: driver=i915 latency=0 resources: irq:46 memory:bfc00000-bfffffff memory:d0000000-dfffffff ioport:4000(size=64) Similarly $ /usr/lib/nux/unity_support_test -p OpenGL vendor string: VMware, Inc. OpenGL renderer string: Gallium 0.4 on llvmpipe (LLVM 3.3, 256 bits) OpenGL version string: 2.1 Mesa 9.2.1 Not software rendered: no Not blacklisted: yes GLX fbconfig: yes GLX texture from pixmap: yes GL npot or rect textures: yes GL vertex program: yes GL fragment program: yes GL vertex buffer object: yes GL framebuffer object: yes GL version is 1.4+: yes Unity 3D supported: no Shows no 3D support. Can anyone please guide how to make things working again.

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  • How do I throttle a command in a terminal window?

    - by To Do
    I needed to run convert with a lot of images at the same time. The command took quite a while but this doesn't bother me. The issue is that this command rendered my computer unusable while the command was running (for about 15 minutes). So is it possible to throttle the command by limiting resources (processor and memory) to the command, directly from the command line? This can only work if I add something to the same line before pressing Enter because once I start the process the computer slows so much that it is impossible for example to switch to "System monitor" and reduce priority. Edit: top and iotop results I managed to run top and sudo iotop >iotop.txt while doing one of these convert operations. (The iotop.txt file produced is difficult to read) Results of top: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 14275 username 20 0 4043m 3.0g 1448 D 7.0 80.4 0:16.45 convert Results of iotop: [?1049h[1;24r(B[m[4l[?7h[?1h=[39;49m[?25l[39;49m(B[m[H[2JTotal DISK READ: 1269.04 K/s | Total DISK WRITE:[59G0.00 B/s (B[0;7m TID PRIO USER DISK READ DISK WRITE SWAPIN(B[0;1;7m IO(B[0;7m COMMAND [3;2H(B[m2516 be/4 username 350.08 K/s 0.00 B/s 0.00 % 0.00 % zeitgeist-datahub 7394 be/4 username 568.88 K/s 0.00 B/s 77.41 % 0.00 % --rendere~.530483991[5;1H14275 idle username 350.08 K/s 0.00 B/s 37.49 % 0.00 % convert S~f test.pdf[6;2H2048 be/4 root[6;24H0.00 B/s 0.00 B/s 0.00 % 0.00 % [kworker/3:2] [5G1 be/4 root[7;24H0.00 B/s 0.00 B/s 0.00 % 0.00 % init Furthermore, even after the process ends, the computer does not return to the previous performance. I found a way around this by running sudo swapoff -a followed by sudo swapon -a

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  • Understanding Application binary interface (ABI)

    - by Tim
    I am trying to understand the concept of Application binary interface (ABI). From The Linux Kernel Primer: An ABI is a set of conventions that allows a linker to combine separately compiled modules into one unit without recompilation, such as calling conventions, machine interface, and operating-system interface. Among other things, an ABI defines the binary interface between these units. ... The benefits of conforming to an ABI are that it allows linking object files compiled by different compilers. From Wikipedia: an application binary interface (ABI) describes the low-level interface between an application (or any type of) program and the operating system or another application. ABIs cover details such as data type, size, and alignment; the calling convention, which controls how functions' arguments are passed and return values retrieved; the system call numbers and how an application should make system calls to the operating system; and in the case of a complete operating system ABI, the binary format of object files, program libraries and so on. I was wondering whether ABI depends on both the instruction set and the OS. Are the two all that ABI depends on? What kinds of role does ABI play in different stages of compilation: preprocessing, conversion of code from C to Assembly, conversion of code from Assembly to Machine code, and linking? From the first quote above, it seems to me that ABI is needed for only linking stage, not the other stages. Is it correct? When is ABI needed to be considered? Is ABI needed to be considered during programming in C, Assembly or other languages? If yes, how are ABI and API different? Or is it only for linker or compiler? Is ABI specified for/in machine code, Assembly language, and/or of C?

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  • Software architecture for two similar classes which require different input parameters for the same method

    - by I Like to Code
    I am writing code to simulate a supply chain. The supply chain can be simulated in either an intermediate stocking or a cross-docking configuration. So, I wrote two simulator objects IstockSimulator and XdockSimulator. Since the two objects share certain behaviors (e.g. making shipments, demand arriving), I wrote an abstract simulator object AbstractSimulator which is a parent class of the two simulator objects. The abstract simulator object has a method runSimulation() which takes an input parameter of class SimulationParameters. Up till now, the simulation parameters only contains fields that are common to both simulator objects, such as randomSeed, simulationStartPeriod and simulationEndPeriod. However, I now want to include fields that are specific to the type of simulation that is being run, i.e. an IstockSimulationParameters class for an intermediate stocking simulation, and a XdockSimulationParameters class for a cross-docking simulation. My current idea is take the method runSimulation() out of the AbstractSimulator class, but to put a runSimulation(IstockSimulationParameters) method in the IstockSimulator class, and a runSimulation(XdockSimulationParameters) method in the IstockSimulator class. I am worried however, that this approach will lead to code duplication. What should I do?

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  • Unity on Ubuntu 11.10 - The Dash Home button brings up the panel, but is empty

    - by David M. Coe
    The dash home button brings up a panel that is greyed out, but it is totally empty. It seems to be the very same issue as this: Dash home button brings up blank window which is unanswered. /usr/lib/nux/unity_support_test -p returns OpenGL vendor string: X.Org R300 Project OpenGL renderer string: Gallium 0.4 on ATI RV370 OpenGL version string: 2.1 Mesa 7.11 Not software rendered: yes Not blacklisted: yes GLX fbconfig: yes GLX texture from pixmap: yes GL npot or rect textures: yes GL vertex program: yes GL fragment program: yes GL vertex buffer object: yes GL framebuffer object: yes GL version is 1.4+: yes Unity 3D supported: yes I've tried a unity --reset but that doesn't seem to work. Unity seems to reset, but I get the following warning over and over: cs space validation failed unity What should I do next to try and fix this? Edit: Attempted fixes: I've refomatted, did not work. I've done apt-get remove unity then apt-get update then apt-get install unity, did not work. I've switched to Unity 2d and this seems to work. How can I get regualar Unity working or atleast find the error?

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  • Should we encourage coding styles in favor of developer's autonomy, or discourage it in favor of consistency?

    - by Saeed Neamati
    A developer writes if/else blocks with one-line code statements like: if (condition) // Do this one-line code else // Do this one-line code Another uses curly braces for all of them: if (condition) { // Do this one-line code } else { // Do this one-line code } A developer first instantiates an object, then uses it: HelperClass helper = new HelperClass(); helper.DoSomething(); Another developer instantiates and uses the object in one line: new HelperClass().DoSomething(); A developer is more easy with arrays, and for loops: string[] ordinals = new string[] {'First', 'Second', 'Third'}; for (i = 0; i < ordinals.Length; i++) { // Do something } Another writes: List<string> ordinals = new List<string>() {'First', 'Second', 'Third'}; foreach (string ordinal in ordinals) { // Do something } I'm sure that you know what I'm talking about. I call it coding style (cause I don't know what it's called). But whatever we call it, is it good or bad? Does encouraging it have an effect of higher productivity of developers? Should we ask developers to try to write code the way we tell them, so to make the whole system become style-consistent?

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  • Player & Level class structure in 2D python console game?

    - by Markus Meskanen
    I'm trying to create a 2D console game, where I have a player who can freely move around in a level (~map, but map is a reserved keyword) and interfere with other objects. Levels construct out of multiple Blocks, such as player(s), rocks, etc. Here's the Block class: class Block(object): def __init__(self, x=0, y=0, char=' ', solid=False): self.x = x self.y = y self.char = char self.solid = solid As you see, each block has a position (x, y) and a character to represent the block when it's printed. Each block also has a solid attribute, defining whether it can overlap with other solids or not. (Two solid blocks cannot overlap) I've now created few subclasses from Block (Rock might be useless for now) class Rock(Block): def __init__(self, x=0, y=0): super(Rock, self).__init__(x, y, 'x', True) class Player(Block): def __init__(self, x=0, y=0): super(Player, self).__init__(x, y, 'i', True) def move_left(self, x=1): ... # How do I make sure Player wont overlap with rocks? self.x -= x And here's the Level class: class Level(object): def __init__(self, name='', blocks=None): self.name = name self.blocks = blocks or [] Only way I can think of is to store a Player instance into Level's attributes (self.player=Player(), or so) and then give Level a method: def player_move_left(self): for block in self.blocks: if block.x == self.player.x - 1 and block.solid: return False But this doesn't really make any sense, why have a Player class if it can't even be moved without Level? Imo. player should be moved by a method inside Player. Am I wrong at something here, if not, how could I implement such behavior?

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  • Cannot install ia32-lib package

    - by A British Person
    I have several programs that reuquire 32 bit packages (pointing to the ia32-lib package). However, when I try to install it, this happens. spirit@ubuntu:~$ sudo apt-get install ia32-libs Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: ia32-libs : Depends: ia32-libs-multiarch but it is not installable E: Unable to correct problems, you have held broken packages. No big whoop, packages die all the time. I tried a month later however and I still got this error, trying to install the specific package produces this error. spirit@ubuntu:~$ sudo apt-get install ia32-libs-multiarch Reading package lists... Done Building dependency tree Reading state information... Done Package ia32-libs-multiarch is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source E: Package 'ia32-libs-multiarch' has no installation candidate I am no Linux whizz-kid, but this seems to be that the package doesn't exist. I searched for Skype in the software centre (I was told this installs the 32-bit packages) and it does not appear in the software centre, and the downloadable from their website produces an error about - funnily enough - no 32-bit packages. Anyone who helps me will get a medal from the gods with the weight of a thousand planets. Just don't wear it for god's sake.

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  • Correcting Lighting in Stencil Reflections

    - by Reanimation
    I'm just playing around with OpenGL seeing how different methods of making shadows and reflections work. I've been following this tutorial which describes using GLUT_STENCIL's and MASK's to create a reasonable interpretation of a reflection. Following that and a bit of tweaking to get things to work, I've come up with the code below. Unfortunately, the lighting isn't correct when the reflection is created. glPushMatrix(); plane(); //draw plane that reflection appears on glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE); glDepthMask(GL_FALSE); glEnable(GL_STENCIL_TEST); glStencilFunc(GL_ALWAYS, 1, 0xFFFFFFFF); glStencilOp(GL_REPLACE, GL_REPLACE, GL_REPLACE); plane(); //draw plane that acts as clipping area for reflection glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE); glDepthMask(GL_TRUE); glStencilFunc(GL_EQUAL, 1, 0xFFFFFFFF); glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP); glDisable(GL_DEPTH_TEST); glPushMatrix(); glScalef(1.0f, -1.0f, 1.0f); glTranslatef(0,2,0); glRotatef(180,0,1,0); sphere(radius, spherePos); //draw object that you want to have a reflection glPopMatrix(); glEnable(GL_DEPTH_TEST); glDisable(GL_STENCIL_TEST); sphere(radius, spherePos); //draw object that creates reflection glPopMatrix(); It looked really cool to start with, then I noticed that the light in the reflection isn't correct. I'm not sure that it's even a simple fix because effectively the reflection is also a sphere but I thought I'd ask here none-the-less. I've tried various rotations (seen above the first time the sphere is drawn) but it doesn't seem to work. I figure it needs to rotate around the Y and Z axis but that's not correct. Have I implemented the rotation wrong or is there a way to correct the lighting?

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  • Dealing with Fine-Grained Cache Entries in Coherence

    - by jpurdy
    On occasion we have seen significant memory overhead when using very small cache entries. Consider the case where there is a small key (say a synthetic key stored in a long) and a small value (perhaps a number or short string). With most backing maps, each cache entry will require an instance of Map.Entry, and in the case of a LocalCache backing map (used for expiry and eviction), there is additional metadata stored (such as last access time). Given the size of this data (usually a few dozen bytes) and the granularity of Java memory allocation (often a minimum of 32 bytes per object, depending on the specific JVM implementation), it is easily possible to end up with the case where the cache entry appears to be a couple dozen bytes but ends up occupying several hundred bytes of actual heap, resulting in anywhere from a 5x to 10x increase in stated memory requirements. In most cases, this increase applies to only a few small NamedCaches, and is inconsequential -- but in some cases it might apply to one or more very large NamedCaches, in which case it may dominate memory sizing calculations. Ultimately, the requirement is to avoid the per-entry overhead, which can be done either at the application level by grouping multiple logical entries into single cache entries, or at the backing map level, again by combining multiple entries into a smaller number of larger heap objects. At the application level, it may be possible to combine objects based on parent-child or sibling relationships (basically the same requirements that would apply to using partition affinity). If there is no natural relationship, it may still be possible to combine objects, effectively using a Coherence NamedCache as a "map of maps". This forces the application to first find a collection of objects (by performing a partial hash) and then to look within that collection for the desired object. This is most naturally implemented as a collection of entry processors to avoid pulling unnecessary data back to the client (and also to encapsulate that logic within a service layer). At the backing map level, the NIO storage option keeps keys on heap, and so has limited benefit for this situation. The Elastic Data features of Coherence naturally combine entries into larger heap objects, with the caveat that only data -- and not indexes -- can be stored in Elastic Data.

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  • Triggering Data Changes in N-Tier

    - by Ryan Kinal
    I've been studying n-tier architectures as of late, particularly in VB.NET with Entity Framework and/or LINQ to SQL. I understand the basic concepts, but have been wondering about best practices in regard to triggering CRUD-type operations from user input/action. So, the arcitecture looks something like the following: [presentation layer] - [business layer] - [data layer] - (database) Getting information from the database into the presentation layer is simple and abstracted. It's just a matter of instantiating a new object from the business layer, which in turn uses the data layer to get at the correct information. However, saving (updating and inserting), and deleting seem to require particular APIs on the relevant business objects. I have to assume this is standard practice, unless a business object will save itself on various operations (which seems inefficient), or on disposal (which seems like it just wouldn't work, or may be unwieldy and unreliable). Should my "savable" business objects all implement a particular "ISavable" or "IDatabaseObject" interface? Is this a recognized (anti-)pattern? Are there other, better patterns I should be using that I'm just unaware of? The TLDR question, I suppose, is How does the presentation layer trigger database changes?

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  • Entry level engineer question regarding memory mangement

    - by Ealianis
    It has been a few months since I started my position as an entry level software developer. Now that I am past some learning curves (e.g. the language, jargon, syntax of VB and C#) I'm starting to focus on more esoteric topics, as to write better software. A simple question I presented to a fellow coworker was responded with "I'm focusing on the wrong things." While I respect this coworker I do disagree that this is a "wrong thing" to focus upon. Here was the code (in VB) and followed by the question. Note: The Function GenerateAlert() returns an integer. Dim alertID as Integer = GenerateAlert() _errorDictionary.Add(argErrorID, NewErrorInfo(Now(), alertID)) vs... _errorDictionary.Add(argErrorID, New ErrorInfo(Now(), GenerateAlert())) I originally wrote the ladder and rewrote it with the "Dim alertID" so that someone else might find it easier to read. But here was my concern and question. "Should one write this with the Dim AlertID, it would in fact take up more memory; finite but more, and should this method be called many times could it lead to an issue? How will .NET handle this object AlertID. Outside of .NET should one manually dispose of the object after use (near the end of the sub)." I want to ensure I become a knowledgeable programmer that does not just rely upon garbage collection. Am I over thinking this? Am I focusing on the wrong things?

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  • How can I instruct nautilus to pre-generate PDF thumbnails?

    - by Glutanimate
    I have a large library of PDF documents (papers, lectures, handouts) that I want to be able to quickly navigate through. For that I need thumbnails. At the same time however, I see that the ~/.thumbnails folder is piling up with thumbs I don't really need. Deleting thumbnail junk without removing the important thumbs is impossible. If I were to delete them, I'd have to go to each and every folder with important PDF documents and let the thumbnail cache regenerate. I would love to able to automate this process. Is there any way I can tell nautilus to pre-cache the thumbs for a set of given directories? Note: I did find a set of bash scripts that appear to do this for pictures and videos, but not for any other documents. Maybe someone more experienced with scripting might be able to adjust these for PDF documents or at least point me in the right direction on what I'd have to modify for this to work with PDF documents as well. Edit: Unfortunately neither of the answers provided below work. See my comments below for more information. Is there anyone who can solve this?

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  • Dependency error while installing WINE

    - by pgrytdal
    Every time I try to install "WINE" VIA the Software Center on Ubuntu 12.10, I get this error: The following packages have unmet dependencies: wine1.4: PreDepends: dpkg (>= 1.15.7.2~) but 1.16.7ubuntu6 is to be installed Depends: libc6 (>= 2.14) but 2.15-0ubuntu20 is to be installed Depends: wine1.4-amd64 (= 1.4.1-0ubuntu1) but 1.4.1-0ubuntu1 is to be installed Depends: wine1.4-i386 (= 1.4.1-0ubuntu1) but it is not going to be installed When I try installing it VIA the terminal, this is what I get: Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: wine1.4 : Depends: wine1.4-i386 (= 1.4.1-0ubuntu1) but it is not installable Recommends: gnome-exe-thumbnailer but it is not going to be installed or kde-runtime but it is not going to be installed Recommends: ttf-droid Recommends: ttf-mscorefonts-installer but it is not going to be installed Recommends: ttf-umefont but it is not going to be installed Recommends: ttf-unfonts-core but it is not going to be installed Recommends: winbind but it is not going to be installed Recommends: winetricks but it is not going to be installed E: Unable to correct problems, you have held broken packages. how do I fix this?

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  • GAPI output doesn't match Google Analytics website

    - by Yekver
    I have to get the main info about my Google Analytics Goals. I'm using GAPI lib, with this code: <?php require_once 'conf.inc'; require_once 'gapi.class.php'; $ga = new gapi(ga_email,ga_password); $dimensions = array('pagePath', 'hostname'); $metrics = array('goalCompletionsAll', 'goalConversionRateAll', 'goalValueAll'); $ga->requestReportData(ga_profile_id, $dimensions, $metrics, '-goalCompletionsAll', '', '2012-09-07', '2012-10-07', 1, 500); $gaResults = $ga->getResults(); foreach($gaResults as $result) { var_dump($result); } cut this code is output: object(gapiReportEntry)[7] private 'metrics' => array (size=3) 'goalCompletionsAll' => int 12031 'goalConversionRateAll' => float 206.93154454764 'goalValueAll' => float 0 private 'dimensions' => array (size=2) 'pagePath' => string '/catalogs.php' (length=13) 'hostname' => string 'www.example.com' (length=13) object(gapiReportEntry)[6] private 'metrics' => array (size=3) 'goalCompletionsAll' => int 9744 'goalConversionRateAll' => float 661.05834464043 'goalValueAll' => float 0 private 'dimensions' => array (size=2) 'pagePath' => string '/price.php' (length=10) 'hostname' => string 'www.example.com' (length=13) What I see on Google Analytics website on Goals URLs page with the same period of date is: Goal Completion Location Goal Completions Goal Value 1. /price.php 9,396 $0.00 2. /saloni.php 3,739 $0.00 As you can see outputs doesn't match. Why? What's wrong?

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  • Design Pattern for Skipping Steps in a Wizard

    - by Eric J.
    I'm designing a flexible Wizard system that presents a number of screens to complete a task. Some screens may need to be skipped based on answers to prompts on one or more previous screens. The conditions to skip a given screen need to be editable by a non-technical user via a UI. Multiple conditions need only be combined with and. I have an initial design in mind, but it feels inelegant. I wonder if there's a better way to approach this class of problem. Initial Design UI where The first column allows the user to select a question from a previous screen. The second column allows the user to select an operator applicable to the type of question asked. The third column allows the user to enter one or more values depending on the selected operator. Object Model public enum Operations { ... } public class Condition { int QuestionId { get; set; } Operations Operation { get; set; } List<object> Parameters { get; private set; } } List<Condition> pageSkipConditions; Controller Logic bool allConditionsTrue = pageSkipConditions.Count > 0; foreach (Condition c in pageSkipConditions) { allConditionsTrue &= Evaluate(previousAnswers, c); } // ... private bool Evaluate(List<Answers> previousAnswers, Condition c) { switch (c.Operation) { case Operations.StartsWith: // logic for this operation // etc. } }

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  • Tail-recursive implementation of take-while

    - by Giorgio
    I am trying to write a tail-recursive implementation of the function take-while in Scheme (but this exercise can be done in another language as well). My first attempt was (define (take-while p xs) (if (or (null? xs) (not (p (car xs)))) '() (cons (car xs) (take-while p (cdr xs))))) which works correctly but is not tail-recursive. My next attempt was (define (take-while-tr p xs) (let loop ((acc '()) (ys xs)) (if (or (null? ys) (not (p (car ys)))) (reverse acc) (loop (cons (car ys) acc) (cdr ys))))) which is tail recursive but needs a call to reverse as a last step in order to return the result list in the proper order. I cannot come up with a solution that is tail-recursive, does not use reverse, only uses lists as data structure (using a functional data structure like a Haskell's sequence which allows to append elements is not an option), has complexity linear in the size of the prefix, or at least does not have quadratic complexity (thanks to delnan for pointing this out). Is there an alternative solution satisfying all the properties above? My intuition tells me that it is impossible to accumulate the prefix of a list in a tail-recursive fashion while maintaining the original order between the elements (i.e. without the need of using reverse to adjust the result) but I am not able to prove this. Note The solution using reverse satisfies conditions 1, 3, 4.

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  • Using Queries with Coherence Write-Behind Caches

    - by jpurdy
    Applications that use write-behind caching and wish to query the logical entity set have the option of querying the NamedCache itself or querying the database. In the former case, no particular restrictions exist beyond the limitations intrinsic to the Coherence query engine itself. In the latter case, queries may see partially committed transactions (e.g. with a parent-child relationship, the version of the parent may be different than the version of the child objects) and/or significant version skew (the query may see the current version of one object and a far older version of another object). This is consistent with "read committed" semantics, but the read skew may be far greater than would ever occur in a non-cached environment. As is usually the case, the application developer may choose to accept these limitations (with the hope that they are sufficiently infrequent), or they may choose to validate the reads (perhaps via a version flag on the objects). This also applies to situations where a third party application (such as a reporting tool) is querying the database. In many cases, the database may only be in a consistent state after the Coherence cluster has been halted.

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  • Octrees and Vertex Buffer Objects

    - by sharethis
    As many others I want to code a game with a voxel based terrain. The data is represented by voxels which are rendered using triangles. I head of two different approaches and want to combine them. First, I could once divide the space in chunks of a fixed size like many games do. What I could do now is to generate a polygon shape for each chunk and store that in a vertex buffer object (vbo). Each time a voxel changes, the polygon and vbo of its chunk is recreated. Additionally it is easy to dynamically load and reload parts of the terrain. Another approach would be to use octrees and divide the space in eight cubes which are divided again and again. So I could efficiently render the terrain because I don't have to go deeper in a solid cube and can draw that as a single one (with a repeated texture). What I like to use for my game is an octree datastructure. But I can't imagine how to use vbos with that. How is that done, or is this impossible?

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