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  • Storing pointers in multi-dimensional array

    - by sdfqwerqaz1
    My intention is to create a dynamic 3D array in C++ using pointers. MyType*** myArray; myArray = new MyType**[GRID_SIZE]; for (int i = 0; i < GRID_SIZE; ++i) { myArray[i] = new MyType*[GRID_SIZE]; for (int j = 0; j < GRID_SIZE; ++j) { myArray[i][j] = new MyType[GRID_SIZE]; } } Now this 3D array is ready to store MyType instances. What is the correct syntax needed when declaring this array if I want to store pointers to MyType instead of just MyType objects in this array?

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  • "Address of" (&) an array / address of being ignored be gcc?

    - by dbarbosa
    Hi, I am a teaching assistant of a introductory programming course, and some students made this type of error: char name[20]; scanf("%s",&name); which is not surprising as they are learning... What is surprising is that, besides gcc warning, the code works (at least this part). I have been trying to understand and I wrote the following code: void foo(int *str1, int *str2) { if (str1 == str2) printf("Both pointers are the same\n"); else printf("They are not the same\n"); } int main() { int test[50]; foo(&test, test); if (&test == test) printf("Both pointers are the same\n"); else printf("They are not the same\n"); } Compiling and executing: $ gcc test.c -g test.c: In function ‘main’: test.c:12: warning: passing argument 1 of ‘foo’ from incompatible pointer type test.c:13: warning: comparison of distinct pointer types lacks a cast $ ./a.out Both pointers are the same Both pointers are the same Can anyone explain why they are not different? I suspect it is because I cannot get the address of an array (as I cannot have & &x), but in this case the code should not compile.

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  • how to do partial updates in OpenGL?

    - by Will
    It is general wisdom that you redraw the entire viewport on each frame. I would like to use partial updates; what are the various ways can do that, and what are their pros, cons and relative performance? (Using textures, FBOs, the accumulator buffer, any kind of scissors that can affect swapbuffers etc?) A scenario: a scene with a fair few thousand visible trees; although the textures are mipmapped and they are drawn via VBOs roughly front-to-back with so on, its still a lot of polys. Would streaming a single screen-sized texture be better than throwing them at the screen every frame? You'd have to redraw and recapture them only on camera movement or as often as your wind model updates or whatever, which need not be every frame.

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  • Triple buffering causes input lag?

    - by user782220
    Consider some time in between two vsyncs. Suppose the first display buffer is being used to display the current image, and suppose the game was really fast and computed and rendered the next image to the second display buffer and the next one after that to the third display buffer. That is the rendering to the second and third display buffer happens so fast that it occurs before the next vsync. Suppose input from the user comes in now. What you would like is for the results of the input to show up on the next vsync or (probably more typical) the vsync after that. However, with the third display buffer already rendered the input can only effect the image after that. Meaning the input will only take effect at best 3 vsyncs later. I wish i had an image to show the exact timings of what I mean.

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  • Is using a dedicated thread just for sending gpu commands a good idea?

    - by tigrou
    The most basic game loop is like this : while(1) { update(); draw(); swapbuffers(); } This is very simple but have a problem : some drawing commands can be blocking and cpu will wait while he could do other things (like processing next update() call). Another possible solution i have in mind would be to use two threads : one for updating and preparing commands to be sent to gpu, and one for sending these commands to the gpu : //first thread while(1) { update(); render(); // use gamestate to generate all needed triangles and commands for gpu // put them in a buffer, no command is send to gpu // two buffers will be used, see below pulse(); //signal the other thread data is ready } //second thread while(1) { wait(); // wait for second thread for data to come send_data_togpu(); // send prepared commands from buffer to graphic card swapbuffers(); } also : two buffers would be used, so one buffer could be filled with gpu commands while the other would be processed by gpu. Do you thing such a solution would be effective ? What would be advantages and disadvantages of such a solution (especially against a simpler solution (eg : single threaded with triple buffering enabled) ?

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  • Administrator's shortcut to batch file with double quoted parameters

    - by XXB
    Take an excruciatingly simple batch file: echo hi pause Save that as test.bat. Now, make a shortcut to test.bat. The shortcut runs the batch file, which prints "hi" and then waits for a keypress as expected. Now, add some argument to the target of the shortcut. Now you have a shortcut to: %path%\test.bat some args The shortcut runs the batch file as before. Now, run the shortcut as administrator. (This is on Windows 7 by the way.) You can use either right-click - Run as Administrator, or go to the shortcut's properties and check the box in the advanced section. Tell UAC that it's okay and once again the shortcut runs the batch file as expected. Now, change the arguments in the target of the shortcut to add double quotes: %path%\test.bat "some args" Now try the shortcut as administrator. It doesn't work this time! A command window pops up and and disappears too fast to see any error. I tried adding test.log 2&1 to the shortcut, but no log is created in this case. Try running the same shortcut (with the double quotes) but not as Administrator. It runs the batch file fine. So, it seems the behavior is not because of the double quoted parameters, and it's not because it's run as Administrator. It's some weird combination of the two. I also tried running the same command from an administrator's command window. This ran the batch file as expected without error. Running the shortcut from the command window spawned a new command window which flashed and went away. So apparently the issue is caused by a combination of administrator, the shortcut, and the double quotes. I'm totally stumped, does anyone have any idea what's going on?

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  • Listen to double click not click

    - by Mohsen
    I'm just wondering why click event happening when I dbclick an element? I have this code:(JSBIN) HTML <p id="hello">Hello World</p> JavaScript document.getElementById('hello').addEventListener('click', function(e){ e.preventDefault(); this.style.background = 'red'; }, false); document.getElementById('hello').addEventListener('dbclick', function(){ this.style.background = 'yellow'; }, false); It should do different things for click and double click, but it seems when you double click on the p it catch click event in advance and ignore double click. I tried preventDefault the click event too. How can I listen to just dbclick? UPDATE I had a typo in my code. dbclick is wrong. It's dblclick. Anyway the problem still exist. When user double clicks the click event happens. This is updated code that prove it:(JSBin) document.getElementById('hello').addEventListener('click', function(e){ e.preventDefault(); this.style.background = 'red'; this.innerText = "Hello World clicked"; }, false); document.getElementById('hello').addEventListener('dblclick', function(){ this.style.background = 'green'; }, false);

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  • Perl regex which grabs ALL double letter occurances in a line

    - by phileas fogg
    Hi all, still plugging away at teaching myself Perl. I'm trying to write some code that will count the lines of a file that contain double letters and then place parentheses around those double letters. Now what I've come up with will find the first ocurrance of double letters, but not any other ones. For instance, if the line is: Amp, James Watt, Bob Transformer, etc. These pioneers conducted many My code will render this: 19 Amp, James Wa(tt), Bob Transformer, etc. These pioneers conducted many The "19" is the count (of lines containing double letters) and it gets the "tt" of "Watt" but misses the "ee" in "pioneers". Below is my code: $file = '/path/to/file/electricity.txt'; open(FH, $file) || die "Cannot open the file\n"; my $counter=0; while (<FH>) { chomp(); if (/(\w)\1/) { $counter += 1; s/$&/\($&\)/g; print "\n\n$counter $_\n\n"; } else { print "$_\n"; } } close(FH); What am I overlooking? TIA!

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  • Utility for scanning stacks of double-sided documents

    - by Peter Becich
    I have a simplex scanner with document feeder, and am looking for the best way to scan double-sided notes. It would be useful to be able to scan the same stack twice, once flipped, and have a utility automatically interleave the scanned images. Multi-page PDF export would also be nice. Is there a tool to do this? Otherwise, I'm considering writing it in Python, with the imagescanner module, if it can use the ADF -- http://pypi.python.org/pypi/imagescanner/0.9 Thanks

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  • Direct Link to IRC Server with Double ##

    - by bemental
    Trying to create a direct link to an IRC channel with double octothorpes (##). Freenode policy dictates off-topic channels require ## before the channel name. This O'Reilly 'hack' post gives solid instructions for how to link to a channel and open in the default client on a system, but no guidance for channels with doubles. Links to single channels are formatted as "irc://irc-server:port/channel?key"

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  • WebKit and npapi and mingw-w64

    - by rubenvb
    Hi, The problem is the following: On Windows x64, pointers are 64-bit, but type long is 32-bit. MSVC doesn't seem to care, and even omits warnings about pointer truncation on the default warning level. Since recently, there is a GCC that target x86_64-w64-mingw32, or better Windows x64 native. GCC produces errors when pointers are truncated (which is the logical thing to do...), and this is causing trouble in WebKit and more specifically, the Netscape Plugin API: First, there's the files (I can only post one hyperlink...): http://trac.webkit.org/browser/trunk/WebCore/ bridge/npapi.h -- defines uint32 as 32-bit int type (~line 145) plugins/win/PluginViewWin.cpp -- casts Windows window handles to 32-bit int, truncating them (~line 450) My proposed fix was to change the uint32 casts to uintptr_t, which makes GCC happy, but still puts a 64-bit value in a uint32 (=unsigned long). I have no clue how to solve this, because clearly WebKit is happy truncating pointers on Win64... How can I solve this the right way? Thanks!

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  • Pointers to Derived Class Objects Losing vfptr

    - by duckworthd
    To begin, I am trying to write a run-of-the-mill, simple Ray Tracer. In my Ray Tracer, I have multiple types of geometries in the world, all derived from a base class called "SceneObject". I've included the header for it here. /** Interface for all objects that will appear in a scene */ class SceneObject { public: mat4 M, M_inv; Color c; SceneObject(); ~SceneObject(); /** The transformation matrix to be applied to all points of this object. Identity leaves the object in world frame. */ void setMatrix(mat4 M); void setMatrix(MatrixStack mStack); void getMatrix(mat4& M); /** The color of the object */ void setColor(Color c); void getColor(Color& c); /** Alter one portion of the color, leaving the rest as they were. */ void setDiffuse(vec3 rgb); void setSpecular(vec3 rgb); void setEmission(vec3 rgb); void setAmbient(vec3 rgb); void setShininess(double s); /** Fills 'inter' with information regarding an intersection between this object and 'ray'. Ray should be in world frame. */ virtual void intersect(Intersection& inter, Ray ray) = 0; /** Returns a copy of this SceneObject */ virtual SceneObject* clone() = 0; /** Print information regarding this SceneObject for debugging */ virtual void print() = 0; }; As you can see, I've included a couple virtual functions to be implemented elsewhere. In this case, I have only two derived class -- Sphere and Triangle, both of which implement the missing member functions. Finally, I have a Parser class, which is full of static methods that do the actual "Ray Tracing" part. Here's a couple snippets for relevant portions void Parser::trace(Camera cam, Scene scene, string outputFile, int maxDepth) { int width = cam.getNumXPixels(); int height = cam.getNumYPixels(); vector<vector<vec3>> colors; colors.clear(); for (int i = 0; i< width; i++) { vector<vec3> ys; for (int j = 0; j<height; j++) { Intersection intrsct; Ray ray; cam.getRay(ray, i, j); vec3 color; printf("Obtaining color for Ray[%d,%d]\n", i,j); getColor(color, scene, ray, maxDepth); ys.push_back(color); } colors.push_back(ys); } printImage(colors, width, height, outputFile); } void Parser::getColor(vec3& color, Scene scene, Ray ray, int numBounces) { Intersection inter; scene.intersect(inter,ray); if(inter.isIntersecting()){ Color c; inter.getColor(c); c.getAmbient(color); } else { color = vec3(0,0,0); } } Right now, I've forgone the true Ray Tracing part and instead simply return the color of the first object hit, if any. As you have no doubt noticed, the only way the computer knows that a ray has intersected an object is through Scene.intersect(), which I also include. void Scene::intersect(Intersection& i, Ray r) { Intersection result; result.setDistance(numeric_limits<double>::infinity()); result.setIsIntersecting(false); double oldDist; result.getDistance(oldDist); /* Cycle through all objects, making result the closest one */ for(int ind=0; ind<objects.size(); ind++){ SceneObject* thisObj = objects[ind]; Intersection betterIntersect; thisObj->intersect(betterIntersect, r); double newDist; betterIntersect.getDistance(newDist); if (newDist < oldDist){ result = betterIntersect; oldDist = newDist; } } i = result; } Alright, now for the problem. I begin by creating a scene and filling it with objects outside of the Parser::trace() method. Now for some odd reason, I cast Ray for i=j=0 and everything works wonderfully. However, by the time the second ray is cast all of the objects stored in my Scene no longer recognize their vfptr's! I stepped through the code with a debugger and found that the information to all the vfptr's are lost somewhere between the end of getColor() and the continuation of the loop. However, if I change the arguments of getColor() to use a Scene& instead of a Scene, then no loss occurs. What crazy voodoo is this?

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  • Alternative to c++ static virtual methods

    - by Jaime Pardos
    In C++ is not possible to declare a static virtual function, neither cast a non-static function to a C style function pointer. Now, I have a plain ol' C SDK that uses function pointers heavily. I have to fill a structure with several function pointers. I was planning to use an abstract class with a bunch of static pure virtual methods, and redefine them in derived classes and fill the structure with them. It wasn't until then that I realized that static virtual are not allowed in C++. Is there any good alternative? The best I can think of is defining some pure virtual methods GetFuncA(), GetFuncB(),... and some static members FuncA()/FuncB() in each derived class, which would be returned by the GetFuncX(). Then a function in the abstract class would call those functions to get the pointers and fill the structure.

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  • Printer in a AD double side print problem

    - by Spidfire
    ive got a printer in my Active directory but its standard set to double sided printing but the problem is the printer doesnt support that so you have to switch it manualy Ive found the setting for the user but it is automatically set to the original value if you reboot Where can i find the setting in the active directory ? the printer is a :HP Color LaserJet CP1510 Series PCL 6 (its possible that there is a script for this but i dont know where to look)

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  • Printer in a AD double side print problem

    - by Spidfire
    ive got a printer in my Active directory but its standard set to double sided printing but the problem is the printer doesnt support that so you have to switch it manualy Ive found the setting for the user but it is automatically set to the original value if you reboot Where can i find the setting in the active directory ? the printer is a :HP Color LaserJet CP1510 Series PCL 6 (its possible that there is a script for this but i dont know where to look)

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  • Execute a program by double-clicking the taskbar and/or the desktop, Windows 7

    - by JoePerkins
    It would be so useful, and not very difficult, because in fact I have Directory Opus installed (a very powerful windows explorer alternative) and it does exactly that, but only by double-clicking the desktop, not the taskbar. Similar options with middle-click would also be nice, such as scrolling the taskbar (maybe cycling directly through the Alt-Tab window). 7 Task Tweaker is close to this, actually, but it doesn't do what I would like.

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  • how do I stop excel from adding double quotes to my formula

    - by Alex
    this works: {=MEDIAN((Table1[MonthFinish]=201012)*(Table1[Days]))} but if I put 201012 into cell A3, this doesn't done work: {=MEDIAN((Table1[MonthFinish]=A3)*(Table1[Days]))} when i do Evaluate Formula on the 2nd one...I see that there are double quotes about the 201012 that was pulled from A3...like so: {=MEDIAN((Table1[MonthFinish]="201012")*(Table1[Days]))} and as such, all the 201012s pulled from the MonthFinsh row come back as FALSE when compared to "201012" (ie, 201012="201012" ) where as they come back as TRUE when I hard code 201012 as it shows up as 201012=201012. how do i get even to not put those quotes around the number?

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  • Database Design for a double entry accounting system

    - by Khou
    Should journal entries be recorded in a database design? In the real world it makes sense to keep a daily entry book, then later transfer the daily entry book into double entry accounts. but in the computerized version, doing this produces duplicate records and that doesn't quite make sense? ???? What i mean is 1) user enter details , it gets recorded (this would be called the journalbook in real life) 2) the software does all the double entry accounting then references the journalbook and splits up the transaction into the double entry accounting system.

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  • double.NaN Equality in MS Test

    - by RichK
    Why am I getting this result? [TestMethod] public void nan_test() { Assert.AreEqual(1, double.NaN, 1E-1); <-- Passes Assert.AreEqual(1, double.NaN); <-- Fails } What difference does the delta have in asserting NaN equals a number? Surely it should always return false. I am aware of IsNaN, but that's not useful here (see below). Background: I have a function returning NaN (erroneously) , it was meant to be a real number but the test still passed. I'm using the delta because it's double precision equality, the original test used 1E-9.

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