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  • Object pools for efficient resource management

    - by GameDevEnthusiast
    How can I avoid using default new() to create each object? My previous demo had very unpleasant framerate hiccups during dynamic memory allocations (usually, when arrays are resized), and creating lots of small objects which often contain one pointer to some DirectX resource seems like an awful lot of waste. I'm thinking about: Creating a master look-up table to refer to objects by handles (for safety & ease of serialization), much like EntityList in source engine Creating a templated object pool, which will store items contiguously (more cache-friendly, fast iteration, etc.) and the stored elements will be accessed (by external systems) via the global lookup table. The object pool will use the swap-with-last trick for fast removal (it will invoke the object's ~destructor first) and will update the corresponding indices in the global table accordingly (when growing/shrinking/moving elements). The elements will be copied via plain memcpy(). Is it a good idea? Will it be safe to store objects of non-POD types (e.g. pointers, vtable) in such containers? Related post: Dynamic Memory Allocation and Memory Management

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  • Update to SQL Server Configuration Scripting Utility

    - by Bill Graziano
    Last spring I released a utility to script SQL Server configuration information on CodePlex.  I’ve been making small changes in this application as my needs have changed.  The application is a .NET 2.0 console application.  This utility serves two needs for me.  First it helps with disaster recovery.  All server level objects (logins, jobs, linked servers, audits) are scripted to a single file per object type.  This enables the scripts to be easily run against a DR server.  If these are checked into source control you can view the history of the script and find out what changed and when. The second goal is to capture what changed inside a database.  Objects inside a database (tables, stored procedures, views, etc.) are each scripted to their own file.  This makes it easier to track the changes to an object over time.  This does include permissions and role membership so you can capture security changes.  My assumption is that a database backup is the primary method of disaster recovery for databases so this utility is designed to capture changes to objects.  You can find the full list of changes from the original on the Downloads page on CodePlex.

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  • C#, Delegates and LINQ

    - by JustinGreenwood
    One of the topics many junior programmers struggle with is delegates. And today, anonymous delegates and lambda expressions are profuse in .net APIs.  To help some VB programmers adapt to C# and the many equivalent flavors of delegates, I walked through some simple samples to show them the different flavors of delegates. using System; using System.Collections.Generic; using System.Linq; namespace DelegateExample { class Program { public delegate string ProcessStringDelegate(string data); public static string ReverseStringStaticMethod(string data) { return new String(data.Reverse().ToArray()); } static void Main(string[] args) { var stringDelegates = new List<ProcessStringDelegate> { //========================================================== // Declare a new delegate instance and pass the name of the method in new ProcessStringDelegate(ReverseStringStaticMethod), //========================================================== // A shortcut is to just and pass the name of the method in ReverseStringStaticMethod, //========================================================== // You can create an anonymous delegate also delegate (string inputString) //Scramble { var outString = inputString; if (!string.IsNullOrWhiteSpace(inputString)) { var rand = new Random(); var chs = inputString.ToCharArray(); for (int i = 0; i < inputString.Length * 3; i++) { int x = rand.Next(chs.Length), y = rand.Next(chs.Length); char c = chs[x]; chs[x] = chs[y]; chs[y] = c; } outString = new string(chs); } return outString; }, //========================================================== // yet another syntax would be the lambda expression syntax inputString => { // ROT13 var array = inputString.ToCharArray(); for (int i = 0; i < array.Length; i++) { int n = (int)array[i]; n += (n >= 'a' && n <= 'z') ? ((n > 'm') ? 13 : -13) : ((n >= 'A' && n <= 'Z') ? ((n > 'M') ? 13 : -13) : 0); array[i] = (char)n; } return new string(array); } //========================================================== }; // Display the results of the delegate calls var stringToTransform = "Welcome to the jungle!"; System.Console.ForegroundColor = ConsoleColor.Cyan; System.Console.Write("String to Process: "); System.Console.ForegroundColor = ConsoleColor.Yellow; System.Console.WriteLine(stringToTransform); stringDelegates.ForEach(delegatePointer => { System.Console.WriteLine(); System.Console.ForegroundColor = ConsoleColor.Cyan; System.Console.Write("Delegate Method Name: "); System.Console.ForegroundColor = ConsoleColor.Magenta; System.Console.WriteLine(delegatePointer.Method.Name); System.Console.ForegroundColor = ConsoleColor.Cyan; System.Console.Write("Delegate Result: "); System.Console.ForegroundColor = ConsoleColor.White; System.Console.WriteLine(delegatePointer(stringToTransform)); }); System.Console.ReadKey(); } } } The output of the program is below: String to Process: Welcome to the jungle! Delegate Method Name: ReverseStringStaticMethod Delegate Result: !elgnuj eht ot emocleW Delegate Method Name: ReverseStringStaticMethod Delegate Result: !elgnuj eht ot emocleW Delegate Method Name: b__1 Delegate Result: cg ljotWotem!le une eh Delegate Method Name: b__2 Delegate Result: dX_V|`X ?| ?[X ]?{Z_X!

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  • Mocking concrete class - Not recommended

    - by Mik378
    I've just read an excerpt of "Growing Object-Oriented Software" book which explains some reasons why mocking concrete class is not recommended. Here some sample code of a unit-test for the MusicCentre class: public class MusicCentreTest { @Test public void startsCdPlayerAtTimeRequested() { final MutableTime scheduledTime = new MutableTime(); CdPlayer player = new CdPlayer() { @Override public void scheduleToStartAt(Time startTime) { scheduledTime.set(startTime); } } MusicCentre centre = new MusicCentre(player); centre.startMediaAt(LATER); assertEquals(LATER, scheduledTime.get()); } } And his first explanation: The problem with this approach is that it leaves the relationship between the objects implicit. I hope we've made clear by now that the intention of Test-Driven Development with Mock Objects is to discover relationships between objects. If I subclass, there's nothing in the domain code to make such a relationship visible, just methods on an object. This makes it harder to see if the service that supports this relationship might be relevant elsewhere and I'll have to do the analysis again next time I work with the class. I can't figure out exactly what he means when he says: This makes it harder to see if the service that supports this relationship might be relevant elsewhere and I'll have to do the analysis again next time I work with the class. I understand that the service corresponds to MusicCentre's method called startMediaAt. What does he mean by "elsewhere"? The complete excerpt is here: http://www.mockobjects.com/2007/04/test-smell-mocking-concrete-classes.html

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  • How to use mount points in MilkShape models?

    - by vividos
    I have bought the Warriors & Commoners model pack from Frogames and the pack contains (among other formats) two animated models and several non-animated objects (axe, shield, pilosities, etc.) in MilkShape3D format. I looked at the official "MilkShape 3D Viewer v2.0" (msViewer2.zip at http://www.chumba.ch/chumbalum-soft/ms3d/download.html) source code and implemented loading the model, calculating the joint matrices and everything looks fine. In the model there are several joints that are designated as the "mount points" for the static objects like axe and shield. I now want to "put" the axe into the hand of the animated model, and I couldn't quite figure out how. I put the animated vertices in a VBO that gets updated every frame (I know I should do this with a shader, but I didn't have time to do this yet). I put the static vertices in another VBO that I want to keep static and not updated every frame. I now tried to render the animated vertices first, then use the joint matrix for the "mount joint" to calculate the location of the static object. I tried many things, and what about seems to be right is to transpose the joint matrix, then use glMatrixMult() to transform the modelview matrix. For some objects like the axe this is working, but not for others, e.g. the pilosities. Now my question: How is this generally implemented when using bone/joint models, and especially with MilkShape3D models? Am I on the right track?

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  • Boolean checks with a single quadtree, or multiple quadtrees?

    - by Djentleman
    I'm currently developing a 2D sidescrolling shooter game for PC (think metroidvania but with a lot more happening at once). Using XNA. I'm utilising quadtrees for my spatial partitioning system. All objects will be encompassed by standard bounding geometry (box or sphere) with possible pixel-perfect collision detection implemented after geometry collision (depends on how optimised I can get it). These are my collision scenarios, with < representing object overlap (multiplayer co-op is the reason for the player<player scenario): Collision scenarios (true = collision occurs): Player <> Player = false Enemy <> Enemy = false Player <> Enemy = true PlayerBullet <> Enemy = true PlayerBullet <> Player = false PlayerBullet <> EnemyBullet = true PlayerBullet <> PlayerBullet = false EnemyBullet <> Player = true EnemyBullet <> Enemy = false EnemyBullet <> EnemyBullet = false Player <> Environment = true Enemy <> Environment = true PlayerBullet <> Environment = true EnemyBullet <> Environment = true Going off this information and the fact that were will likely be several hundred objects rendering on-screen at any given time, my question is as follows: Which method is likely to be the most efficient/optimised and why: Using a single quadtree with boolean checks for collision between the different types of objects. Using three quadtrees at once (player, enemy, environment), only testing the player and enemy trees against each other while testing both the player and enemy trees against the environment tree.

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  • Presentation Plugin for NetBeans IDE 7.2

    - by Geertjan
    I got some excellent help from Mark Stephens, who is from IDR Solutions, which produces JPedal. Using the LGPL version of JPedal, and code provided by Mark, it's now possible to right-click the node that appears in the Presentation Window: ...after which, using a file browser (to locate a file on disk) or a URL (a very simple check is done, the URL must start with "http" and end with "pdf"), you can now open PDF files as images (thanks to conversion from PDF to images done by JPedal) into NetBeans IDE, typically (I imagine) for presentation purposes: Note that you should consider the plugin in "alpha" state. But, despite that, I've had good results. Try it and use the URL below, as a control test (since it works fine for me), which produces the result shown above: http://edu.netbeans.org/contrib/slides/netbeans-platform/presentation-4-actions.pdf  However, for some PDFs, the plugin doesn't work, and I don't know why yet (trying to figure it out with Mark), resulting in this stack trace: java.lang.ArrayIndexOutOfBoundsException: 8 at org.jpedal.objects.acroforms.formData.SwingData.completeField(Unknown Source) at org.jpedal.objects.acroforms.rendering.DefaultAcroRenderer.createField(Unknown Source) at org.jpedal.objects.acroforms.rendering.DefaultAcroRenderer.createDisplayComponentsForPage(Unknown Source) at org.jpedal.PDFtoImageConvertor.convert(Unknown Source) at org.jpedal.PdfDecoder.getPageAsImage(Unknown Source) at org.jpedal.PdfDecoder.getPageAsImage(Unknown Source) Here's the location of the plugin, install it into NetBeans IDE 7.2; feedback is very welcome: http://plugins.netbeans.org/plugin/44525

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  • how to properly implement alpha blending in a complex 3d scene

    - by Gajet
    I know this question might sound a bit easy to answer but It's driving me crazy. There are too many possible situations that a good alpha blending mechanism should handle, and for each Algorithm I can think of there is something missing. these are the methods I've though about so far: first of I though about object sorting by depth, this one simply fails because Objects are not simple shapes, they might have curves and might loop inside each other. so I can't always tell which one is closer to camera. then I thought about sorting triangles but this one also might fail, thought I'm not sure how to implement it there is a rare case that might again cause problem, in which two triangle pass through each other. again no one can tell which one is nearer. the next thing was using depth buffer, at least the main reason we have depth buffer is because of the problems with sorting that I mentioned but now we get another problem. Since objects might be transparent, in a single pixel there might be more than one object visible. So for which Object should I store pixel depth? I then thought maybe I can only store the most front Object depth, and using that determine how should I blend next draw calls at that pixel. But again there was a problem, think about 2 semi transparent planes with a solid plane in middle of them. I was going to render the solid plane at the end, one can see the most distant plane. note that I was going to merge every two planes until there is only one color left for that pixel. Obviously I can use sorting methods too because of the same reasons I've explained above. Finally the only thing I imagine being able to work is to render all objects into different render targets and then sort those layers and display the final output. But this time I don't know how can I implement this algorithm.

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  • Unity Problem with colliding instances of same object

    - by Kuba Sienkiewicz
    I want to check if object's instance is overlapping with another instance (any spawned object with another spawned object, not necessary the same object). I'm doing this by detecting collisions between bodies. But I have a problem. Spawned object (instances) are detecting collision with everything but other spawned objects. I've checked collision layers etc. All of spawned objects have rigidbodies and mesh colliders. Also when I attach my script to another body and I touch that body with an instanced object it detects collision. So problem is visible only in collision between spawned objects. And one more information I have script, rigid body and collider attached to child of main object. using UnityEngine; using System.Collections; public class CantPlace : MonoBehaviour { public bool collided = false; // Use this for initialization void Start () { } // Update is called once per frame void Update () { //Debug.Log (collided); } void OnTriggerEnter(Collider collider) { //if (true) { //foreach (Transform child in this.transform) { // if (child.name == "Cylinder") { //collided = true; Color c; c = this.renderer.material.color; c.g = 0f; c.b = 1f; c.r = 0f; this.renderer.material.color = c; Debug.Log (collider.name); //} // } //} //foreach (ContactPoint contact in collision.contacts) { // Debug.DrawRay(contact.point, contact.normal, Color.red,15f); // } } }

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  • The long road to bug-free software

    - by Tony Davis
    The past decade has seen a burgeoning interest in functional programming languages such as Haskell or, in the Microsoft world, F#. Though still on the periphery of mainstream programming, functional programming concepts are gradually seeping into the imperative C# language (for example, Lambda expressions have their root in functional programming). One of the more interesting concepts from functional programming languages is the use of formal methods, the lofty ideal behind which is bug-free software. The idea is that we write a specification that describes exactly how our function (say) should behave. We then prove that our function conforms to it, and in doing so have proved beyond any doubt that it is free from bugs. All programmers already use one form of specification, specifically their programming language's type system. If a value has a specific type then, in a type-safe language, the compiler guarantees that value cannot be an instance of a different type. Many extensions to existing type systems, such as generics in Java and .NET, extend the range of programs that can be type-checked. Unfortunately, type systems can only prevent some bugs. To take a classic problem of retrieving an index value from an array, since the type system doesn't specify the length of the array, the compiler has no way of knowing that a request for the "value of index 4" from an array of only two elements is "unsafe". We restore safety via exception handling, but the ideal type system will prevent us from doing anything that is unsafe in the first place and this is where we start to borrow ideas from a language such as Haskell, with its concept of "dependent types". If the type of an array includes its length, we can ensure that any index accesses into the array are valid. The problem is that we now need to carry around the length of arrays and the values of indices throughout our code so that it can be type-checked. In general, writing the specification to prove a positive property, even for a problem very amenable to specification, such as a simple sorting algorithm, turns out to be very hard and the specification will be different for every program. Extend this to writing a specification for, say, Microsoft Word and we can see that the specification would end up being no simpler, and therefore no less buggy, than the implementation. Fortunately, it is easier to write a specification that proves that a program doesn't have certain, specific and undesirable properties, such as infinite loops or accesses to the wrong bit of memory. If we can write the specifications to prove that a program is immune to such problems, we could reuse them in many places. The problem is the lack of specification "provers" that can do this without a lot of manual intervention (i.e. hints from the programmer). All this might feel a very long way off, but computing power and our understanding of the theory of "provers" advances quickly, and Microsoft is doing some of it already. Via their Terminator research project they have started to prove that their device drivers will always terminate, and in so doing have suddenly eliminated a vast range of possible bugs. This is a huge step forward from saying, "we've tested it lots and it seems fine". What do you think? What might be good targets for specification and verification? SQL could be one: the cost of a bug in SQL Server is quite high given how many important systems rely on it, so there's a good incentive to eliminate bugs, even at high initial cost. [Many thanks to Mike Williamson for guidance and useful conversations during the writing of this piece] Cheers, Tony.

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  • How should I structure moving from overworld to menu system / combat?

    - by persepolis
    I'm making a text-based "Arena" game where the player is the owner of 5 creatures that battle other teams for loot, experience and glory. The game is very simple, using Python and a curses emulator. I have a static ASCII map of an "overworld" of sorts. My character, represented by a glyph, can move about this static map. There are locations all over the map that the character can visit, that break down into two types: 1) Towns, which are a series of menus that will allow the player to buy equipment for his team, hire new recruits or do other things. 2) Arenas, where the player's team will have a "battle" interface with actions he can perform, messages about the fight, etc. Maybe later, an ASCII representation of the fight but for now, just screens of information with action prompts. My main problem is what kind of design or structure I should use to implement this? Right now, the game goes through a master loop which waits for keyboard input and then moves the player about the screen. My current thinking is this: 1) Upon keyboard input, the Player coordinates are checked against a list of Location objects and if the Player coords match the Location coords then... 2) ??? I'm not sure if I should then call a seperate function to initiate a "menu" or "combat" mode. Or should I create some kind of new GameMode object that contains a method itself for drawing the screen, printing the necessary info? How do I pass my player's team data into this object? My main concern is passing around the program flow into all these objects. Should I be calling straight functions for different parts of my game, and objects to represent "things" within my game? I was reading about the MVC pattern and how this kind of problem might benefit - decouple the GUI from the game logic and user input but I have no idea how this applies to my game.

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  • Memory allocation strategy for the vertex buffers (DirectX 10/11)

    - by Alex
    I have the following question. I write CAD system. So I have a 3D scene and there are many different objects (walls, doors, windows and so on). User can add or delete some objects. The question is: how can I organise the keeping of vertices for all my objects. I can create vertex buffer for every object. But I think drawing/switching from one buffer to another would have performance penalty. Another way - I can create several big buffers for every object type. But I don't understand how to update such buffers. It is too big to update whole buffer (for example buffer for all walls). What I need to do if I want to delete the object from the middle of the buffer? Actually I have the similar question: http://stackoverflow.com/questions/5515700/how-to-properly-update-vertex-buffers-in-directx-10 Most examples I've found work with very static models. Therefore, they tend to create a single vertex buffer with their list of points, and then are just manipulated by matrix transformations. I, on the other hand, will be updating the scene very often.

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  • Looking for a better Factory pattern (Java)

    - by Sam Goldberg
    After doing a rough sketch of a high level object model, I am doing iterative TDD, and letting the other objects emerge as a refactoring of the code (as it increases in complexity). (That whole approach may be a discussion/argument for another day.) In any case, I am at the point where I am looking to refactor code blocks currently in an if-else blocks into separate objects. This is because there is another another value combination which creates new set of logical sub-branches. To be more specific, this is a trading system feature, where buy orders have different behavior than sell orders. Responses to the orders have a numeric indicator field which describes some event that occurred (e.g. fill, cancel). The combination of this numeric indicator field plus whether it is a buy or sell, require different processing buy the code. Creating a family of objects to separate the code for the unique handling each of the combinations of the 2 fields seems like a good choice at this point. The way I would normally do this, is to create some Factory object which when called with the 2 relevant parameters (indicator, buysell), would return the correct subclass of the object. Some times I do this pattern with a map, which allows to look up a live instance (or constructor to use via reflection), and sometimes I just hard code the cases in the Factory class. So - for some reason this feels like not good design (e.g. one object which knows all the subclasses of an interface or parent object), and a bit clumsy. Is there a better pattern for solving this kind of problem? And if this factory method approach makes sense, can anyone suggest a nicer design?

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  • Is white the best base color to start with when planning to shade sprites within Unity?

    - by SpartanDonut
    I'm looking into prototyping a game in Unity which will consist of solid square sprites / tiles. I figure I can represent different types of objects with different colors for each of the tiles in the game. I figure that I can import a single square sprite and shade it appropriately in Unity as opposed to imported squares of many different colors. My experience with adjusting the hue and saturation within Photoshop shows that white is not an easy color to change as things that are white often stay white. My testing in Unity shows that I can change the "color" of a sprite to anything other than white and the sprite is seemingly shaded appropriately, despite what I would have thought given my Photoshop experience. Since white objects do seem to take on the appropriate color shading when changed within Unity my gut tells me that this is the best base color to begin with, meaning that I can import a single white square sprite and simply adjust the color to represent different objects and object states. Is a white sprite actually the best color sprite to begin with and why does something like this work in Unity as opposed to adjusting the hue and saturation within Photoshop?

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  • Android - big game universe

    - by user1641923
    I am new to an Android development, though I have much experience with Java, C++, PHP programming and a bit experience with vector graphics too (basic 3d Studio Max, Flash, etc). I am starting to work on an Android game. It is going to be a 2D space shooter/RPG, and I am not going to use any game engines and any 3D party libs. I really want to create a very large game universe, or even pseudo-infinite (without visible borders, as if it were a 2D projection of a sphere). It should include 10-12 clusters of 7-8 planets/other space objects and random amount of single asteroids/comets, which player can interact with and also not interactive background. I am looking for a least complicated aproach to create such a universe. My current ideas are: Simply create bitmaps with space scenery background so that they can be tiled seamlessly repeated and construct my 2D universe of this tiles, then place interactive objects (planets, other spaceships) on it. Using vector graphics. I would have a solid color background, some random background objects and gradients here and there. My problems here: Lack of knowledge of how well vector graphics is integrated in Android. Performance? Memory usage? Does Android manage big bitmaps well? Do all of the bitmaps have to be in memory during all game process? I am interested in technical details regarding each of the ideas and a suggestion, which I should go with.

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  • What's the right/standard way of achieving separation of concerns?

    - by Ghanima
    Some background: I want to start developing games, and taking some of the advice given in this site, I've started with something simple and familiar, such as pong, tetris, etc. I want to take as much time as needed to make sure that I have the basics right before moving on to something bigger. I have medium programming experience but I realize making games is a different thing. I find myself wondering many things like should this be in a separate class? Should this module handle this stuff or is it better to let other modules have that kind of functionality? For example, the bouncing of a ball in pong, right now is handled in the ball module, but maybe it's better that some other module did it. Right now I have different modules: one for the graphics, one for the game logic, and others for the objects (depending on the kind of movement required, not all the objects are alike). I know I am asking a lot, any tips you have will be very much appreciated. Short question: What's the right or standard way of separating the modules? What have you found most effective? Is it enough to just keep the drawing (graphics) and the logic separate? Is it necessary to have a lot of classes? (for example for the objects in the game, to handle the movement, etc)

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  • DirectX particle system. ConstantBuffer

    - by Liuka
    I'm new in DirectX and I'm making a 2D game. I want to use a particle system to simulate a 3D starfield, so each star has to set its own constant buffer for the vertexshader es. to set it's world matrix. So if i have 500 stars (that move every frame) i need to call 500 times VSsetconstantbuffer, and map/unmap each buffer. with 500 stars i have an average of 220 fps and that's quite good. My bottelneck is Vs/PsSetconstantbuffer. If i dont call this function i have 400 fps(obliviously nothing is display, since i dont set the position of the stars). So is there a method to speed up the render of the particle system?? Ps. I'm using intel integrate graphic (hd 2000-3000). with a nvidia (or amd) gpu will i have the same bottleneck?? If, for example, i dont call setshaderresource i have 10-20 fps more (for 500 objcets), that is not 180.Why does SetConstantBuffer take so long?? LPVOID VSdataPtr = VSmappedResource.pData; memcpy(VSdataPtr, VSdata, CszVSdata); context->Unmap(VertexBuffer, 0); result = context->Map(PixelBuffer, 0, D3D11_MAP_WRITE_DISCARD, 0, &PSmappedResource); if (FAILED(result)) { outputResult.OutputErrorMessage(TITLE, L"Cannot map the PixelBuffer", &result, OUTPUT_ERROR_FILE); return; } LPVOID PSdataPtr = PSmappedResource.pData; memcpy(PSdataPtr, PSdata, CszPSdata); context->Unmap(PixelBuffer, 0); context->VSSetConstantBuffers(0, 1, &VertexBuffer); context->PSSetConstantBuffers(0, 1, &PixelBuffer); this update and set the buffer. It's part of the render method of a sprite class that contains a the vertex buffer and the texture to apply to the quads(it's a 2d game) too. I have an array of 500 stars (sprite setup with a star texture). Every frame: clear back buffer; draw the array of stars; present the backbuffer; draw also call the function update( which calculate the position of the sprite on screen based on a "camera class") Ok, create a vertex buffer with the vertices of each quads(stars) seems to be good, since the stars don't change their "virtual" position; so.... In a particle system (where particles move) it's better to have all the object in only one vertices array, rather then an array of different sprite/object in order to update all the vertices' position with a single setbuffer call. In this case i have to use a dynamic vertex buffer with the vertices positions like this: verticesForQuad={{ XMFLOAT3((float)halfDImensions.x-1+pos.x, (float)halfDImensions.y-1+pos.y, 1.0f), XMFLOAT2(1.0f, 0.0f) }, { XMFLOAT3((float)halfDImensions.x-1+pos.x, -(float)halfDImensions.y-1+pos.y, 1.0f), XMFLOAT2(1.0f, 1.0f) }, { XMFLOAT3(-(float)halfDImensions.x-1+pos.x, (float)halfDImensions.y-1.pos.y, 1.0f), XMFLOAT2(0.0f, 0.0f) }, { XMFLOAT3(-(float)halfDImensions.x-1.pos.x, -(float)halfDImensions.y-1+pos.y, 1.0f), XMFLOAT2(0.0f, 1.0f) }, ....other quads} where halfDimensions is the halfsize in pixel of a texture and pos the virtual position of a star. than create an array of verticesForQuad and create the vertex buffer ZeroMemory(&vertexDesc, sizeof(vertexDesc)); vertexDesc.Usage = D3D11_USAGE_DEFAULT; vertexDesc.BindFlags = D3D11_BIND_VERTEX_BUFFER; vertexDesc.ByteWidth = sizeof(VertexType)* 4*numStars; ZeroMemory(&resourceData, sizeof(resourceData)); resourceData.pSysMem = verticesForQuad; result = device->CreateBuffer(&vertexDesc, &resourceData, &CvertexBuffer); and call each frame Context->IASetVertexBuffers(0, 1, &CvertexBuffer, &stride, &offset); But if i want to add and remove obj i have to recreate the buffer each time, havent i?? There is a faster way? I think i can create a vertex buffer with a max size (es. 10000 objs) and when i update it set only the 250 position (for 250 onjs for example) and pass this number as the vertexCount to the draw function (numObjs*4), or i'm worng

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  • Is there a standard way to track 2d tile positions both locally and on screen?

    - by Magicked
    I'm building a 2D engine based on 32x32 tiles with OpenGL. OpenGL draws from the top left, so Y coordinates go down the screen as they increase. Obviously this is different than a standard graph where Y coordinates move up as they increase. I'm having trouble determining how I want to track positions for both sprites and tile objects (objects that are collections of tiles). My brain wants to set the world position as the bottom left of the object and track every object this way. The problem with this is I would have to translate it to an on screen position on rendering. The positive with this is I could easily visualize (especially in the case of objects made of multiple tiles) how something is structured and needs to be built. Are there standard ways for doing this? Should I just suck it up and get used to positions beginning in the top left? Here are the OpenGL calls to start rendering: // enable textures since we're going to use these for our sprites glEnable(GL_TEXTURE_2D); glClearColor(0.0f, 0.0f, 0.0f, 0.0f); // enable alpha blending glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); // disable the OpenGL depth test since we're rendering 2D graphics glDisable(GL_DEPTH_TEST); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho(0, WIDTH, HEIGHT, 0, 1, -1); glMatrixMode(GL_MODELVIEW); I assume I need to change: glOrtho(0, WIDTH, HEIGHT, 0, 1, -1); to: glOrtho(0, WIDTH, 0, HEIGHT, 1, -1);

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  • Use a SQL Database for a Desktop Game

    - by sharethis
    Developing a Game Engine I am planning a computer game and its engine. There will be a 3 dimensional world with first person view and it will be single player for now. The programming language is C++ and it uses OpenGL. Data Centered Design Decision My design decision is to use a data centered architecture where there is a global event manager and a global data manager. There are many components like physics, input, sound, renderer, ai, ... Each component can trigger and listen to events. Moreover, each component can read, edit, create and remove data. The question is about the data manager. Whether to Use a Relational Database Should I use a SQL Database, e.g. SQLite or MySQL, to store the game data? This contains virtually all game content like items, characters, inventories, ... Except of meshes and textures which are even more performance related, so I will keep them in memory. Is a SQL database fast enough to use it for realtime reading and writing game informations, like the position of a moving character? I also need to care about cross-platform compatibility. Aside from keeping everything in memory, what alternatives do I have? Advantages Would Be The advantages of using a relational database like MySQL would be the data orientated structure which allows fast computation. I would not need objects for representing entities. I could easily query data of objects near the player needed for rendering. And I don't have to take care about data of objects far away. Moreover there would be no need for savegames since the hole game state is saved in the database. Last but not least, expanding the game to an online game would be relative easy because there already is a place where the hole game state is stored.

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  • Using Bullet physics engine to find the moment of object contact before penetration

    - by MooMoo
    I would like to use Bullet Physics engine to simulate the objects in 3D world. One of the objects in the world will move using the position from 3D mouse control. I will call it "Mouse Object" and any object in the world as "Object A" I define the time before "mouse object" and "Object A" collide as t-1 The time "mouse object" penetrate "Object A" as t Now there is a problem about rendering the scene because when I move the mouse very fast, "Mouse object" will reside in "Object A" before "Object A" start to move. I would like the "Mouse Object" to stop right away attach to the "Object A". Also If the "Object A" move, the "Mouse object" should move following (attach) the "Object A" without stop at the first collision take place. This is what i did I find the position of the "Mouse Object" at time t-1 and time t. I will name it as pos(t-1) and pos(t) The contact time will be sometime between t-1 to t, which the time of contact I name it as t_contact, therefore the contact position (without penetration) between "Mouse object" and "Object A" will be pos(t_contact) then I create multiple "Mouse object"s using this equation pos[n] = pos(t-1) * C * ( pos(t) - pos(t-1) ) where 0 <= C <= 1 if I choose C = 0.1, 0.2, 0.3,0.4..... 1.0, I will get pos[n] for 10 values Then I test collision for all of these 10 "Mouse Objects" and choose the one that seperate between "no collision" and "collision". I feel this method is super non-efficient. I am not sure the way other people find the time-of-contact or the position-of-contact when "Object A" can move.

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  • The long road to bug-free software

    - by Tony Davis
    The past decade has seen a burgeoning interest in functional programming languages such as Haskell or, in the Microsoft world, F#. Though still on the periphery of mainstream programming, functional programming concepts are gradually seeping into the imperative C# language (for example, Lambda expressions have their root in functional programming). One of the more interesting concepts from functional programming languages is the use of formal methods, the lofty ideal behind which is bug-free software. The idea is that we write a specification that describes exactly how our function (say) should behave. We then prove that our function conforms to it, and in doing so have proved beyond any doubt that it is free from bugs. All programmers already use one form of specification, specifically their programming language's type system. If a value has a specific type then, in a type-safe language, the compiler guarantees that value cannot be an instance of a different type. Many extensions to existing type systems, such as generics in Java and .NET, extend the range of programs that can be type-checked. Unfortunately, type systems can only prevent some bugs. To take a classic problem of retrieving an index value from an array, since the type system doesn't specify the length of the array, the compiler has no way of knowing that a request for the "value of index 4" from an array of only two elements is "unsafe". We restore safety via exception handling, but the ideal type system will prevent us from doing anything that is unsafe in the first place and this is where we start to borrow ideas from a language such as Haskell, with its concept of "dependent types". If the type of an array includes its length, we can ensure that any index accesses into the array are valid. The problem is that we now need to carry around the length of arrays and the values of indices throughout our code so that it can be type-checked. In general, writing the specification to prove a positive property, even for a problem very amenable to specification, such as a simple sorting algorithm, turns out to be very hard and the specification will be different for every program. Extend this to writing a specification for, say, Microsoft Word and we can see that the specification would end up being no simpler, and therefore no less buggy, than the implementation. Fortunately, it is easier to write a specification that proves that a program doesn't have certain, specific and undesirable properties, such as infinite loops or accesses to the wrong bit of memory. If we can write the specifications to prove that a program is immune to such problems, we could reuse them in many places. The problem is the lack of specification "provers" that can do this without a lot of manual intervention (i.e. hints from the programmer). All this might feel a very long way off, but computing power and our understanding of the theory of "provers" advances quickly, and Microsoft is doing some of it already. Via their Terminator research project they have started to prove that their device drivers will always terminate, and in so doing have suddenly eliminated a vast range of possible bugs. This is a huge step forward from saying, "we've tested it lots and it seems fine". What do you think? What might be good targets for specification and verification? SQL could be one: the cost of a bug in SQL Server is quite high given how many important systems rely on it, so there's a good incentive to eliminate bugs, even at high initial cost. [Many thanks to Mike Williamson for guidance and useful conversations during the writing of this piece] Cheers, Tony.

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  • Convert collections of enums to collection of strings and vice versa

    - by Michael Freidgeim
    Recently I needed to convert collections of  strings, that represent enum names, to collection of enums, and opposite,  to convert collections of   enums  to collection of  strings. I didn’t find standard LINQ extensions.However, in our big collection of helper extensions I found what I needed - just with different names: /// <summary> /// Safe conversion, ignore any unexpected strings/// Consider to name as Convert extension /// </summary> /// <typeparam name="EnumType"></typeparam> /// <param name="stringsList"></param> /// <returns></returns> public static List<EnumType> StringsListAsEnumList<EnumType>(this List<string> stringsList) where EnumType : struct, IComparable, IConvertible, IFormattable     { List<EnumType> enumsList = new List<EnumType>(); foreach (string sProvider in stringsList)     {     EnumType provider;     if (EnumHelper.TryParse<EnumType>(sProvider, out provider))     {     enumsList.Add(provider);     }     }     return enumsList;     }/// <summary> /// Convert each element of collection to string /// </summary> /// <typeparam name="T"></typeparam> /// <param name="objects"></param> /// <returns></returns> public static IEnumerable<string> ToStrings<T>(this IEnumerable<T> objects) {//from http://www.c-sharpcorner.com/Blogs/997/using-linq-to-convert-an-array-from-one-type-to-another.aspx return objects.Select(en => en.ToString()); }

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  • What OO Design to use ( is there a Design Pattern )?

    - by Blundell
    I have two objects that represent a 'Bar/Club' ( a place where you drink/socialise). In one scenario I need the bar name, address, distance, slogon In another scenario I need the bar name, address, website url, logo So I've got two objects representing the same thing but with different fields. I like to use immutable objects, so all the fields are set from the constructor. One option is to have two constructors and null the other fields i.e: class Bar { private final String name; private final Distance distance; private final Url url; public Bar(String name, Distance distance){ this.name = name; this.distance = distance; this.url = null; } public Bar(String name, Url url){ this.name = name; this.distance = null; this.url = url; } // getters } I don't like this as you would have to null check when you use the getters In my real example the first scenario has 3 fields and the second scenario has about 10, so it would be a real pain having two constructors, the amount of fields I would have to declare null and then when the object are in use you wouldn't know which Bar you where using and so what fields would be null and what wouldn't. What other options do I have? Two classes called BarPreview and Bar? Some type of inheritance / interface? Something else that is awesome?

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  • In developing a soap client proxy, which return structure is easier to use and more sensible?

    - by cori
    I'm writing (in PHP) a client/proxy for a SOAP web service. The return types are consistently wrapped in response objects that contain the return values. In many cases this make a lot of sense - for instance when multiple values are being returned: GetDetailsResponse Object ( Results Object ( [TotalResults] => 10 [NextPage] => 2 ) [Details] => Array ( [0] => Detail Object ( [Id] => 1 ) ) ) But some of the methods return a single scalar value or a single object or array wrapped in a response object: GetThingummyIdResponse Object ( [ThingummyId] => 42 ) In some cases these objects might be pretty deep, so getting at properties within requires drilling down several layers: $response->Details->Detail[0]->Contents->Item[5]->Id And if I unwrap them before passing them back I can strip out a layer from consumers' code. I know I'm probably being a little bit of an Architecture Astronaut here, but the latter style really bug me, so I've been working through my code to have my proxy methods just return the scalar value to the client code where there's no absolute need for a wrapper object. My question is, am I actually making things more difficult for the consumers of my code? Would I be better off just leaving the return values wrapped in response objects so that everything is consistent, or is removing unneccessary layers of indirection/abstraction worthwhile?

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  • Rotating object around moving object/player in 2D

    - by Boston
    I am trying to implement a camera which rotates around the world around the player. I have found many solutions online to the task of rotating an object about the origin, or about an arbitrary point. The procedure seems to be to translate the point to be rotated about to the origin, perform the rotation, translate back, then draw. I have gotten this working for rotation around the origin as well as for a fixed point. Rotation of objects around the player works as well, provided the player does not move. However, if the objects are rotated around the player by some non-zero degree, if the player moves after the rotation it causes the rotated objects to move as well. I probably have done a poor job explaining this so here's an image: http://i.imgur.com/1n63iWR.gif And here's the code for the behavior: renderx = (Ox - Px)*cos(camAngle) - (Oy - Py)*sin(camAngle) + Px; rendery = (Ox - Px)*sin(camAngle) + (Oy - Py)*cos(camAngle) + Py; Where (Ox,Oy) is the actual position of the object to be rotated and (Px,Py) is the actual position of the player. Any ideas? I am using C++ with SDL2.0.

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