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  • How to implement Fog Of War with an shader?

    - by Cambrano
    Okay, I'm creating a RTS game and want to implement an AgeOfEmpires-like Fog Of War(FOW). That means a tile(or pixel) can be: 0% transparent (unexplored) 50% transparent black (explored but not in viewrange) 100% transparent(explored and in viewrange) RTS means I'll have many explorers (NPCs, buildings, ...). Okay, so I have an 2d array of bytes byte[,] explored. The byte value correlates the transparency. The question is, how do I pass this array to my shader? Well I think it is not possible to pass an entire array. So: what technique shall I use to let my shader know if a pixel/tile is visible or not?

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  • How to implement the light trails for a tron game?

    - by Link
    Well I was creating a TRON style game, but had an issue with creating the actual light trails for the game. What I'm doing currently is I have an array the same size as my window in pixel size, implemented like this: int* collision[800][600]; Then when the bike goes on a certain pixel, it is marked with a 1 for traveled on. However what is the most efficient way to create a working light trail display? I tried to do something like this: int i, j; for(i=0; i<800; i++) for(j=0; j<600; j++) if(*collision[i][j] == 1) Image::applySurface(i, j, trailSurface, gameScreen); But it isn't working properly? It just fills the whole screen with a sprite instead. Whats a better/faster/working way to do this?

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  • HLSL: An array of textures and sampler states

    - by nate142
    The shader must switch between multiple textures depending on the Alpha value of the original texture for each pixel. Now this would word fine if I didn't have to worry about SamplerStates. I have created my array of textures and can select a texture based on the Alpha value of the pixel. But how do I create an Array of SamplerStates and link it to my array of textures? I attempted to treat the SamplerState as a function by adding the (int i) but that didn't work. Also I can't use Texture.Sample since this is shader model 2.0. //shader model 2.0 (DX9) texture subTextures[255]; SamplerState MeshTextureSampler(int i) { Texture = (subTextures[i]); }; float4 SampleCompoundTexture(float2 texCoord, float4 diffuse) { float4 SelectedColor = SAMPLE_TEXTURE(Texture, texCoord); int i = SelectedColor.a; texture SelectedTx = subTextures[i]; return tex2D(MeshTextureSampler(i), texCoord) * diffuse; }

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  • Create Adventure Game Scene/Room/Backdrop from Real Photo

    - by Lyuben
    Is there a suitable software or a good tutorial for creating 2D rooms/scenery for adventure games from real photos? Is it possible to achieve good results by using photos, or the hand-drawn style will always be the best choice? Thank you! --- EDIT --- I want to clarify that I'm particularly interested in the art creation process, not on the environment in which to build games. I'm writing the game in Java for Android, but I don't think it matters. Also, I'm not trying to decide if the game will have photo realistic rooms or not - I want to achieve 2d pixelated, old-school style background scenes and I wonder if this can be made from photos, because I cannot draw them myself. For example, can I shoot a scene with my camera and then make it look something like the image in the following link: PIXEL ART FOREST I know that I cannot get the same quality as an absolutely hand-drawn pixel, but I'm looking for some decent technology/tutorial/software to make them somewhat similar.

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  • Marching squares: Finding multiple contours within one source field?

    - by TravisG
    Principally, this is a follow-up-question to a problem from a few weeks ago, even though this is about the algorithm in general without application to my actual problem. The algorithm basically searches through all lines in the picture, starting from the top left of it, until it finds a pixel that is a border. In pseudo-C++: int start = 0; for(int i=0; i<amount_of_pixels; ++i) { if(pixels[i] == border) { start = i; break; } } When it finds one, it starts the marching squares algorithm and finds the contour to whatever object the pixel belongs to. Let's say I have something like this: Where everything except the color white is a border. And have found the contour points of the first blob: For the general algorithm it's over. It found a contour and has done its job. How can I move on to the other two blobs to find their contours as well?

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  • Scan-Line Z-Buffering Dilemma

    - by Belgin
    I have a set of vertices in 3D space, and for each I retain the following information: Its 3D coordinates (x, y, z). A list of pointers to some of the other vertices with which it's connected by edges. Right now, I'm doing perspective projection with the projecting plane being XY and the eye placed somewhere at (0, 0, d), with d < 0. By doing Z-Buffering, I need to find the depth of the point of a polygon (they're all planar) which corresponds to a certain pixel on the screen so I can hide the surfaces that are not visible. My questions are the following: How do I determine to which polygon does a pixel belong to so I could use the formula of the plane which contains the polygon to find the Z-coordinate? Are my data structures correct? Do I need to store something else entirely in order for this to work? I'm just projecting the vertices onto the projection plane and joining them with lines based on the pointer lists.

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  • View space lighting in deferred shading

    - by kochol
    I implemented a simple deferred shading renderer. I use 3 G-Buffer for storing position (R32F), normal (G16R16F) and albedo (ARGB8). I use sphere map algorithm to store normals in world space. Currently I use inverse of view * projection matrix to calculate the position of each pixel from stored depth value. First I want to avoid per pixel matrix multiplication for calculating the position. Is there another way to store and calculate position in G-Buffer without the need of matrix multiplication Store the normal in view space Every lighting in my engine is in world space and I want do the lighting in view space to speed up my lighting pass. I want an optimized lighting pass for my deferred engine.

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  • Are these non-standard applications of rendering practical in games?

    - by maul
    I've recently got into 3D and I came up with a few different "tricky" rendering techniques. Unfortunately I don't have the time to work on this myself, but I'd like to know if these are known methods and if they can be used in practice. Hybrid rendering Now I know that ray-tracing is still not fast enough for real-time rendering, at least on home computers. I also know that hybrid rendering (a combination of rasterization and ray-tracing) is a well known theory. However I had the following idea: one could separate a scene into "important" and "not important" objects. First you render the "not important" objects using traditional rasterization. In this pass you also render the "important" objects using a special shader that simply marks these parts on the image using a special color, or some stencil/depth buffer trickery. Then in the second pass you read back the results of the first pass and start ray tracing, but only from the pixels that were marked by the "important" object's shader. This would allow you to only ray-trace exactly what you need to. Could this be fast enough for real-time effects? Rendered physics I'm specifically talking about bullet physics - intersection of a very small object (point/bullet) that travels across a straight line with other, relatively slow-moving, fairly constant objects. More specifically: hit detection. My idea is that you could render the scene from the point of view of the gun (or the bullet). Every object in the scene would draw a different color. You only need to render a 1x1 pixel window - the center of the screen (again, from the gun's point of view). Then you simply check that central pixel and the color tells you what you hit. This is pixel-perfect hit detection based on the graphical representation of objects, which is not common in games. Afaik traditional OpenGL "picking" is a similar method. This could be extended in a few ways: For larger (non-bullet) objects you render a larger portion of the screen. If you put a special-colored plane in the middle of the scene (exactly where the bullet will be after the current frame) you get a method that works as the traditional slow-moving iterative physics test as well. You could simulate objects that the bullet can pass through (with decreased velocity) using alpha blending or some similar trick. So are these techniques in use anywhere, and/or are they practical at all?

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  • Things to do to port game made for iOS in Unity to Android?

    - by 2600th
    I have just made my first game for iOS and submitted it to app store. I was thinking of porting my game to Android also. I would like to know things one need to do/remember to port game made for iOS in Unity to Android. How to handle different screen resolutions and pixel densities, optimizations required, etc. Any other suggestions and important things you think I should know? EDIT: Also, should I handle builds according to device resolutions or by pixel density?

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  • Java graphic objects as in flashgames

    - by Ryu Kajiya
    How is it possible (with the standard Java2D engine) to use small sprites like graphic objects? For those who don't know what I mean, in all those Flash-games like on Facebook they put small sprites on the screen which react to mouse-over and clicks. I tried to do the same in Java but can't find a good method. Swing components always spread over the whole bitmap, but I only want to get a reaction from the object when the mouse is over a pixel that's not transparent. So basically checking every time if the object below the mouse contains a non-transparent pixel (which i believe could be pretty intense in a gameloop or repaint loop). I have no idea how to implement such a thing efficiently.

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  • Without using a pre-built physics engine, how can I implement 3-D collision detection from scratch?

    - by Andy Harglesis
    I want to tackle some basic 3-D collision detection and was wondering how engines handle this and give you a pretty interface and make it so easy ... I want to do it all myself, however. 2-D collision detection is extremely simple and can be done multiple ways that even beginner programmers could think up: 1.When the pixels touch; 2.when a rectangle range is exceeded; 3.when a pixel object is detected near another one in a pixel-based rendering engine. But 3-D is different with one dimension, but complex in many more so ... what are the general, basic understanding/examples on how 3-D collision detection can be implemented? Think two shaded, OpenGL cubes that are moved next to each other with a simple OpenGL rendering context and keyboard events.

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  • openGL textures in bitmap mode

    - by evenex_code
    For reasons detailed here I need to texture a quad using a bitmap (as in, 1 bit per pixel, not an 8-bit pixmap). Right now I have a bitmap stored in an on-device buffer, and am mounting it like so: glBindBuffer(GL_PIXEL_UNPACK_BUFFER, BFR.G[(T+1)%2]); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, W, H, 0, GL_COLOR_INDEX, GL_BITMAP, 0); The OpenGL spec has this to say about glTexImage2D: "If type is GL_BITMAP, the data is considered as a string of unsigned bytes (and format must be GL_COLOR_INDEX). Each data byte is treated as eight 1-bit elements..." Judging by the spec, each bit in my buffer should correspond to a single pixel. However, the following experiments show that, for whatever reason, it doesn't work as advertised: 1) When I build my texture, I write to the buffer in 32-bit chunks. From the wording of the spec, it is reasonable to assume that writing 0x00000001 for each value would result in a texture with 1-px-wide vertical bars with 31-wide spaces between them. However, it appears blank. 2) Next, I write with 0x000000FF. By my apparently flawed understanding of the bitmap mode, I would expect that this should produce 8-wide bars with 24-wide spaces between them. Instead, it produces a white 1-px-wide bar. 3) 0x55555555 = 1010101010101010101010101010101, therefore writing this value ought to create 1-wide vertical stripes with 1 pixel spacing. However, it creates a solid gray color. 4) Using my original 8-bit pixmap in GL_BITMAP mode produces the correct animation. I have reached the conclusion that, even in GL_BITMAP mode, the texturer is still interpreting 8-bits as 1 element, despite what the spec seems to suggest. The fact that I can generate a gray color (while I was expecting that I was working in two-tone), as well as the fact that my original 8-bit pixmap generates the correct picture, support this conclusion. Questions: 1) Am I missing some kind of prerequisite call (perhaps for setting a stride length or pack alignment or something) that will signal to the texturer to treat each byte as 8-elements, as it suggests in the spec? 2) Or does it simply not work because modern hardware does not support it? (I have read that GL_BITMAP mode was deprecated in 3.3, I am however forcing a 3.0 context.) 3) Am I better off unpacking the bitmap into a pixmap using a shader? This is a far more roundabout solution than I was hoping for but I suppose there is no such thing as a free lunch.

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  • Calling Matlab's MLApp.MLAppClass.FEval from F#

    - by Matthew
    Matlab provides a COM interface that supports remote execution of arbitrary functions (and code snippets). In particular, it has an Feval method that calls a given Matlab function. The third parameter to this method, pvarArgOut, has COM type VARIANT*, and appears in the Visual Studio F# editor as an argument of type: pvarArgOut: byref<obj> The following code calls interp1, which in Matlab returns a matrix (i.e. 2D double array) result, as is normal for most Matlab functions. let matlab = new MLApp.MLAppClass() let vector_to_array2d (v : vector) = Array2D.init v.Length 1 (fun i j -> v.[i]) let interp1 (xs : vector) (ys : vector) (xi : vector) = let yi : obj = new obj() matlab.Feval("interp1", 1, ref yi, vector_to_array2d xs, vector_to_array2d ys, vector_to_array2d xi) yi :?> float[,] This code compiles fine, but when calling interp1, I get a COM exception: A first chance exception of type 'System.Reflection.TargetInvocationException' occurred in mscorlib.dll A first chance exception of type 'System.Runtime.InteropServices.COMException' occurred in mscorlib.dll An unhandled exception of type 'System.Runtime.InteropServices.COMException' occurred in mscorlib.dll Additional information: Invalid callee. (Exception from HRESULT: 0x80020010 (DISP_E_BADCALLEE)) I get the same error whether initialize yi with a new obj, a new Array2D, or null. How does F# translate VARIANT output arguments?

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  • simple Stata program

    - by Cyrus S
    I am trying to write a simple program to combine coefficient and standard error estimates from a set of regression fits. I run, say, 5 regressions, and store the coefficient(s) and standard error(s) of interest into vectors (Stata matrix objects, actually). Then, I need to do the following: Find the mean value of the coefficient estimates. Combine the standard error estimates according to the formula suggested for combining results from "multiple imputation". The formula is the square root of the formula for "T" on page 6 of the following document: http://bit.ly/b05WX3 I have written Stata code that does this once, but I want to write this as a function (or "program", in Stata speak) that takes as arguments the vector (or matrix, if possible, to combine multiple estimates at once) of regression coefficient estimates and the vector (or matrix) of corresponding standard error estimates, and then generates 1 and 2 above. Here is the code that I wrote: (breg is a 1x5 vector of the regression coefficient estimates, and sereg is a 1x5 vector of the associated standard error estimates) mat ones = (1,1,1,1,1) mat bregmean = (1/5)*(ones*breg’) scalar bregmean_s = bregmean[1,1] mat seregmean = (1/5)*(ones*sereg’) mat seregbtv = (1/4)*(breg - bregmean#ones)* (breg - bregmean#ones)’ mat varregmi = (1/5)*(sereg*sereg’) + (1+(1/5))* seregbtv scalar varregmi_s = varregmi[1,1] scalar seregmi = sqrt(varregmi_s) disp bregmean_s disp seregmi This gives the right answer for a single instance. Any pointers would be great! UPDATE: I completed the code for combining estimates in a kXm matrix of coefficients/parameters (k is the number of parameters, m the number of imputations). Code can be found here: http://bit.ly/cXJRw1 Thanks to Tristan and Gabi for the pointers.

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  • Statically Compiling QWebKit 4.6.2

    - by geeko
    I tried to compile Qt+Webkit statically with MS VS 2008 and this worked. C:\Qt\4.6.2configure -release -static -opensource -no-fast -no-exceptions -no-accessibility -no-rtti -no-stl -no-opengl -no-openvg -no-incredibuild-xge -no-style-plastique -no-style-cleanlooks -no-style-motif -no-style-cde -no-style-windowsce -no-style-windowsmobile -no-style-s60 -no-gif -no-libpng -no-libtiff -no-libjpeg -no-libmng -no-qt3support -no-mmx -no-3dnow -no-sse -no-sse2 -no-iwmmxt -no-openssl -no-dbus -platform win32-msvc2008 -arch windows -no-phonon -no-phonon-backend -no-multimedia -no-audio-backend -no-script -no-scripttools -webkit -no-declarative However, I get these errors whenever building a project that links statically to QWebKit: 1 Creating library C:\Users\Geeko\Desktop\Qt\TestQ\Release\TestQ.lib and object C:\Users\Geeko\Desktop\Qt\TestQ\Release\TestQ.exp 1QtWebKit.lib(PluginPackageWin.obj) : error LNK2019: unresolved external symbol _VerQueryValueW@16 referenced in function "class WebCore::String __cdecl WebCore::getVersionInfo(void * const,class WebCore::String const &)" (?getVersionInfo@WebCore@@YA?AVString@1@QAXABV21@@Z) 1QtWebKit.lib(PluginPackageWin.obj) : error LNK2019: unresolved external symbol _GetFileVersionInfoW@16 referenced in function "private: bool __thiscall WebCore::PluginPackage::fetchInfo(void)" (?fetchInfo@PluginPackage@WebCore@@AAE_NXZ) 1QtWebKit.lib(PluginPackageWin.obj) : error LNK2019: unresolved external symbol _GetFileVersionInfoSizeW@8 referenced in function "private: bool __thiscall WebCore::PluginPackage::fetchInfo(void)" (?fetchInfo@PluginPackage@WebCore@@AAE_NXZ) 1QtWebKit.lib(PluginDatabaseWin.obj) : error LNK2019: unresolved external symbol _imp_PathRemoveFileSpecW@4 referenced in function "class WebCore::String __cdecl WebCore::safariPluginsDirectory(void)" (?safariPluginsDirectory@WebCore@@YA?AVString@1@XZ) 1QtWebKit.lib(PluginDatabaseWin.obj) : error LNK2019: unresolved external symbol _imp_SHGetValueW@24 referenced in function "void __cdecl WebCore::addWindowsMediaPlayerPluginDirectory(class WTF::Vector &)" (?addWindowsMediaPlayerPluginDirectory@WebCore@@YAXAAV?$Vector@VString@WebCore@@$0A@@WTF@@@Z) 1QtWebKit.lib(PluginDatabaseWin.obj) : error LNK2019: unresolved external symbol _imp_PathCombineW@12 referenced in function "void __cdecl WebCore::addMacromediaPluginDirectories(class WTF::Vector &)" (?addMacromediaPluginDirectories@WebCore@@YAXAAV?$Vector@VString@WebCore@@$0A@@WTF@@@Z) 1C:\Users\Geeko\Desktop\Qt\TestQ\Release\TestQ.exe : fatal error LNK1120: 6 unresolved externals Do I need to check something in the Qt project options ? I have QtCore, QtGui, Network and WebKit checked.

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  • Parsing string, with Boost Spirit 2, to fill data in user defined struct

    - by Surya
    I'm using Boost.Spirit which was distributed with Boost-1.42.0 with VS2005. My problem is like this. I've this string which was delimted with commas. The first 3 fields of it are strings and rest are numbers. like this. String1,String2,String3,12.0,12.1,13.0,13.1,12.4 My rule is like this qi::rule<string::iterator, qi::skip_type> stringrule = *(char_ - ',') qi::rule<string::iterator, qi::skip_type> myrule= repeat(3)[*(char_ - ',') >> ','] >> (double_ % ',') ; I'm trying to store the data in a structure like this. struct MyStruct { vector<string> stringVector ; vector<double> doubleVector ; } ; MyStruct var ; I've wrapped it in BOOST_FUSION_ADAPT_STRUCTURE to use it with spirit. BOOST_FUSION_ADAPT_STRUCT (MyStruct, (vector<string>, stringVector) (vector<double>, doubleVector)) My parse function parses the line and returns true and after qi::phrase_parse (iterBegin, iterEnd, myrule, boost::spirit::ascii::space, var) ; I'm expecting var.stringVector and var.doubleVector are properly filled. but it is not the case. What is going wrong ? Thanks in advance, Surya

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  • Ho to make Histogram Normalize and Equalize in java using JAI library?

    - by Jay
    I m making App in java using Swing component and JAI library. I make histogram of black and white or gray scale image.Is this method of making histogram correct? iif it is correct then how can i do normalization and Equalization of histogram in my App in java using JAI library?my code is below. in my code i make BufferedImage object and then make and plot histogram of that image . enter code here import java.awt.Color; import java.awt.Graphics; import java.awt.image.BufferedImage; import java.io.IOException; import javax.media.jai.JAI; import javax.media.jai.PlanarImage; import javax.swing.*; public class FinalHistogram extends JPanel { static int[] bins = new int[256]; static int[] newBins = new int[256]; static int x1 = 0, y1 = 0; static PlanarImage image = JAI.create("fileload", "alp_finger.tiff"); static BufferedImage bi = image.getAsBufferedImage(); FinalHistogram(int[] pbins) { for (int i = 0; i < 256; i++) { bins[i] = pbins[i]; newBins[i] = 0; } repaint(); } @Override protected void paintComponent(Graphics g) { for (int i = 0; i < 256; i++) { g.drawLine(150 + i, 300, 150 + i, 300 - (bins[i] / 300)); if (i == 0 || i == 255) { String sr = new Integer((i)).toString(); g.drawString(sr, 150 + i, 305); } System.out.println("bin[" + i + "]===" + bins[i]); } } public static void main(String[] args) throws IOException { int[] sbins = new int[256]; int pixel = 0; int k = 0; for (int x = 0; x < bi.getWidth(); x++) { for (int y = 0; y < bi.getHeight(); y++) { pixel = bi.getRaster().getSample(x, y, 0); k = (int) (pixel / 256); sbins[k]++; //pixel = bi.getRGB(x, y) & 0x000000ff; //k=pixel; //int[] pixels = m_image.getRGB(0, 0, m_image.getWidth(), m_image.getHeight(), null, 0, m_image.getWidth()); //short currentValue = 0; //int red,green,blue; //for(int i = 0; i<pixels.length; i++){ //red = (pixels[i] >> 16) & 0x000000FF; //green = (pixels[i] >>8 ) & 0x000000FF; //blue = pixels[i] & 0x000000FF; //currentValue = (short)((red + green + blue) / 3); //Current value gives the average //Disregard the alpha //assert(currentValue >= 0 && currentValue <= 255); //Something is awfully wrong if this goes off... //m_histogramArray[currentValue] += 1; //Increment the specific value of the array //} } } JTabbedPane jtp = new JTabbedPane(); jtp.addTab("Histogram", new JScrollPane(new FinalHistogram(sbins))); JFrame frame = new JFrame(); frame.setSize(500, 500); frame.add(new JScrollPane(jtp)); frame.setVisible(true); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); } }

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  • Boost Mersenne Twister: how to seed with more than one value?

    - by Eamon Nerbonne
    I'm using the boost mt19937 implementation for a simulation. The simulation needs to be reproducible, and that means storing and potentially reusing the RNG seeds later. I'm using the windows crypto api to generate the seed values because I need an external source for the seeds and not because of any particular guarantees of randomness. The output of any simulation run will have a note including the RNG seed - so the seed needs to be reasonably short. On the other hand, as part of the analysis of the simulation, I'll be comparing several runs - but to be sure that these runs are actually different, I'll need to use different seeds - so the seed needs to be long enough to avoid accidental collisions. I've determined that 64-bits of seeding should suffice; the chance of a collision will reach 50% after about 2^32 runs - that probability is low enough that the average error caused by it is negligible to me. Using just 32-bits of seed is tricky; the chance of a collision reaches 50% already after 2^16 runs; and that's a little too likely for my tastes. Unfortunately, the boost implementation either seeds with a full state vector - which is far, far too long - or a single 32-bit unsigned long - which isn't ideal. How can I seed the generator with more than 32-bits but less than a full state vector? I tried just padding the vector or repeating the seeds to fill the state vector, but even a cursory glance at the results shows that that generates poor results.

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  • Ways std::stringstream can set fail/bad bit?

    - by Evan Teran
    A common piece of code I use for simple string splitting looks like this: inline std::vector<std::string> split(const std::string &s, char delim) { std::vector<std::string> elems; std::stringstream ss(s); std::string item; while(std::getline(ss, item, delim)) { elems.push_back(item); } return elems; } Someone mentioned that this will silently "swallow" errors occurring in std::getline. And of course I agree that's the case. But it occurred to me, what could possibly go wrong here in practice that I would need to worry about. basically it all boils down to this: inline std::vector<std::string> split(const std::string &s, char delim) { std::vector<std::string> elems; std::stringstream ss(s); std::string item; while(std::getline(ss, item, delim)) { elems.push_back(item); } if(ss.fail()) { // *** How did we get here!? *** } return elems; } A stringstream is backed by a string, so we don't have to worry about any of the issues associated with reading from a file. There is no type conversion going on here since getline simply reads until it sees a newline or EOF. So we can't get any of the errors that something like boost::lexical_cast has to worry about. I simply can't think of something besides failing to allocate enough memory that could go wrong, but that'll just throw a std::bad_alloc well before the std::getline even takes place. What am I missing?

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  • best way to pick a random subset from a collection?

    - by Tom
    I have a set of objects in a Vector from which I'd like to select a random subset (e.g. 100 items coming back; pick 5 randomly). In my first (very hasty) pass I did an extremely simple and perhaps overly clever solution: Vector itemsVector = getItems(); Collections.shuffle(itemsVector); itemsVector.setSize(5); While this has the advantage of being nice and simple, I suspect it's not going to scale very well, i.e. Collections.shuffle() must be O(n) at least. My less clever alternative is Vector itemsVector = getItems(); Random rand = new Random(System.currentTimeMillis()); // would make this static to the class List subsetList = new ArrayList(5); for (int i = 0; i < 5; i++) { // be sure to use Vector.remove() or you may get the same item twice subsetList.add(itemsVector.remove(rand.nextInt(itemsVector.size()))); } Any suggestions on better ways to draw out a random subset from a Collection?

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  • How to keep only duplicates efficiently?

    - by Marc Eaddy
    Given an STL vector, I'd like an algorithm that outputs only the duplicates in sorted order, e.g., INPUT : { 4, 4, 1, 2, 3, 2, 3 } OUTPUT: { 2, 3, 4 } The algorithm is trivial, but the goal is to make it as efficient as std::unique(). My naive implementation modifies the container in-place: My naive implementation: void keep_duplicates(vector<int>* pv) { // Sort (in-place) so we can find duplicates in linear time sort(pv->begin(), pv->end()); vector<int>::iterator it_start = pv->begin(); while (it_start != pv->end()) { size_t nKeep = 0; // Find the next different element vector<int>::iterator it_stop = it_start + 1; while (it_stop != pv->end() && *it_start == *it_stop) { nKeep = 1; // This gets set redundantly ++it_stop; } // If the element is a duplicate, keep only the first one (nKeep=1). // Otherwise, the element is not duplicated so erase it (nKeep=0). it_start = pv->erase(it_start + nKeep, it_stop); } } If you can make this more efficient, elegant, or general, please let me know. For example, a custom sorting algorithm, or copy elements in the 2nd loop to eliminate the erase() call.

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  • richfaces progressBar polling

    - by John
    Hi, I've got a progressBar component defined as the following on my webpage: <rich:modalPanel id="pb1Panel"> <rich:progressBar id="pb1" oncomplete="javascript:#{myBean.handleProgressEvent()} closeProgressModalPanel()" value="#{pb1Listener.percentageComplete}" label="#{pb1Listener.percentageComplete} %" minValue="1" maxValue="100" limitToList="true" timeout="3200" interval="1400" enabled="false"/> </rich:modalPanel> and a button: <a4j:commandButton id="actButton" value="action" action="#{myBean.performAction}" immediate="true" ajaxSingle="true" onclick="javascript:Richfaces.showModalPanel('pb1Panel');" reRender="pb1Panel"> <a4j:support event="onClick" value="#{rich:component('pb1')}.enable()" reRender="pb1" /> </a4j:commandButton> which doesn't work. However if I take out the .... enabled="false"/> .... from the progress bar, and the element from the button, everything seems to work just fine. Any suggestion why it's not working? I'm setting enabled="false" initially because I do not want the polling to start unless the button was clicked (to reduce unnecessary polling). The system is building on richfaces/seam. Thanks!

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  • Declaring functors for comparison ??

    - by Mr.Gando
    Hello, I have seen other people questions but found none that applied to what I'm trying to achieve here. I'm trying to sort Entities via my EntityManager class using std::sort and a std::vector<Entity *> /*Entity.h*/ class Entity { public: float x,y; }; struct compareByX{ bool operator()(const GameEntity &a, const GameEntity &b) { return (a.x < b.x); } }; /*Class EntityManager that uses Entitiy*/ typedef std::vector<Entity *> ENTITY_VECTOR; //Entity reference vector class EntityManager: public Entity { private: ENTITY_VECTOR managedEntities; public: void sortEntitiesX(); }; void EntityManager::sortEntitiesX() { /*perform sorting of the entitiesList by their X value*/ compareByX comparer; std::sort(entityList.begin(), entityList.end(), comparer); } I'm getting a dozen of errors like : error: no match for call to '(compareByX) (GameEntity* const&, GameEntity* const&)' : note: candidates are: bool compareByX::operator()(const GameEntity&, const GameEntity&) I'm not sure but ENTITY_VECTOR is std::vector<Entity *> , and I don't know if that could be the problem when using the compareByX functor ? I'm pretty new to C++, so any kind of help is welcome.

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  • Issue with clipping rectangles and back to front rendering

    - by Milo
    Here is my problem. My rendering algorithm renders from back to front. But logically, clipping rectangles need to be applied from front to back. Hence why the following does not work: void AguiWidgetManager::recursiveRender(const AguiWidget *root) { //recursively calls itself to render widgets from back to front AguiWidget* nonConstRoot = (AguiWidget*)root; if(!nonConstRoot->isVisable()) { return; } //push the clipping rectangle if(nonConstRoot->isClippingChildren()) { graphicsContext->pushClippingRect(nonConstRoot->getClippingRectangle()); } if(nonConstRoot->isEnabled()) { nonConstRoot->paint(AguiPaintEventArgs(true,graphicsContext)); for(std::vector<AguiWidget*>::const_iterator it = root->getPrivateChildBeginIterator(); it != root->getPrivateChildEndIterator(); ++it) { recursiveRender(*it); } for(std::vector<AguiWidget*>::const_iterator it = root->getChildBeginIterator(); it != root->getChildEndIterator(); ++it) { recursiveRender(*it); } } else { nonConstRoot->paint(AguiPaintEventArgs(false,graphicsContext)); for(std::vector<AguiWidget*>::const_iterator it = root->getPrivateChildBeginIterator(); it != root->getPrivateChildEndIterator(); ++it) { recursiveRenderDisabled(*it); } for(std::vector<AguiWidget*>::const_iterator it = root->getChildBeginIterator(); it != root->getChildEndIterator(); ++it) { recursiveRenderDisabled(*it); } } //release clipping rectangle if(nonConstRoot->isClippingChildren()) { graphicsContext->popClippingRect(); } } I could ofcourse go to the top of the tree, then apply clipping rectangles inward until I get to the currently rendered widget, but that would involve lots of clipping rectangles @ 60 frames per second. I want to minimize calls to pushing and popping rectangles. What could I do, Thanks

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  • Why might stable_sort be affecting my hashtable values?

    - by zebraman
    I have defined a struct ABC to contain an int ID, string NAME, string LAST_NAME; My procedure is this: Read in a line from an input file. Parse each line into first name and last name and insert into the ABC struct. Also, the struct's ID is given by the number of the input line. Then, push_back the struct into a vector masterlist. I am also hashing these to a hashtable defined as vector< vector , using first name and last name as keywords. That is, If my data is: Garfield Cat Snoopy Dog Cat Man Then for the keyword cash hashes to a vector containing Garfield Cat and Cat Man. I insert the structs into the hashtable using push_back again. The problem is, when I call stable_sort on my masterlist, my hashtable is affected for some reason. I thought it might be happening since the songs are being ordered differently, so I tried making a copy of the masterlist and sorting it and it still affects the hashtable though the original masterlist is unaffected. Any ideas why this might be happening?

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