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  • Search in Projects API

    - by Geertjan
    Today I got some help from Jaroslav Havlin, the creator of the new "Search in Projects API". Below are the steps to create a search provider that finds recently modified files, via a new tab in the "Find in Projects" dialog: Here's how to get to the above result. Create a new NetBeans module project named "RecentlyModifiedFilesSearch". Then set dependencies on these libraries: Search in Projects API Lookup API Utilities API Dialogs API Datasystems API File System API Nodes API Create and register an implementation of "SearchProvider". This class tells the application the name of the provider and how it can be used. It should be registered via the @ServiceProvider annotation.Methods to implement: Method createPresenter creates a new object that is added to the "Find in Projects" dialog when it is opened. Method isReplaceSupported should return true if this provider support replacing, not only searching. If you want to disable the search provider (e.g., there aren't required external tools available in the OS), return false from isEnabled. Method getTitle returns a string that will be shown in the tab in the "Find in Projects" dialog. It can be localizable. Example file "org.netbeans.example.search.ExampleSearchProvider": package org.netbeans.example.search; import org.netbeans.spi.search.provider.SearchProvider; import org.netbeans.spi.search.provider.SearchProvider.Presenter; import org.openide.util.lookup.ServiceProvider; @ServiceProvider(service = SearchProvider.class) public class ExampleSearchProvider extends SearchProvider { @Override public Presenter createPresenter(boolean replaceMode) { return new ExampleSearchPresenter(this); } @Override public boolean isReplaceSupported() { return false; } @Override public boolean isEnabled() { return true; } @Override public String getTitle() { return "Recent Files Search"; } } Next, we need to create a SearchProvider.Presenter. This is an object that is passed to the "Find in Projects" dialog and contains a visual component to show in the dialog, together with some methods to interact with it.Methods to implement: Method getForm returns a JComponent that should contain controls for various search criteria. In the example below, we have controls for a file name pattern, search scope, and the age of files. Method isUsable is called by the dialog to check whether the Find button should be enabled or not. You can use NotificationLineSupport passed as its argument to set a display error, warning, or info message. Method composeSearch is used to apply the settings and prepare a search task. It returns a SearchComposition object, as shown below. Please note that the example uses ComponentUtils.adjustComboForFileName (and similar methods), that modifies a JComboBox component to act as a combo box for selection of file name pattern. These methods were designed to make working with components created in a GUI Builder comfortable. Remember to call fireChange whenever the value of any criteria changes. Example file "org.netbeans.example.search.ExampleSearchPresenter": package org.netbeans.example.search; import java.awt.FlowLayout; import javax.swing.BoxLayout; import javax.swing.JComboBox; import javax.swing.JComponent; import javax.swing.JLabel; import javax.swing.JPanel; import javax.swing.JSlider; import javax.swing.event.ChangeEvent; import javax.swing.event.ChangeListener; import org.netbeans.api.search.SearchScopeOptions; import org.netbeans.api.search.ui.ComponentUtils; import org.netbeans.api.search.ui.FileNameController; import org.netbeans.api.search.ui.ScopeController; import org.netbeans.api.search.ui.ScopeOptionsController; import org.netbeans.spi.search.provider.SearchComposition; import org.netbeans.spi.search.provider.SearchProvider; import org.openide.NotificationLineSupport; import org.openide.util.HelpCtx; public class ExampleSearchPresenter extends SearchProvider.Presenter { private JPanel panel = null; ScopeOptionsController scopeSettingsPanel; FileNameController fileNameComboBox; ScopeController scopeComboBox; ChangeListener changeListener; JSlider slider; public ExampleSearchPresenter(SearchProvider searchProvider) { super(searchProvider, false); } /** * Get UI component that can be added to the search dialog. */ @Override public synchronized JComponent getForm() { if (panel == null) { panel = new JPanel(); panel.setLayout(new BoxLayout(panel, BoxLayout.PAGE_AXIS)); JPanel row1 = new JPanel(new FlowLayout(FlowLayout.LEADING)); JPanel row2 = new JPanel(new FlowLayout(FlowLayout.LEADING)); JPanel row3 = new JPanel(new FlowLayout(FlowLayout.LEADING)); row1.add(new JLabel("Age in hours: ")); slider = new JSlider(1, 72); row1.add(slider); final JLabel hoursLabel = new JLabel(String.valueOf(slider.getValue())); row1.add(hoursLabel); row2.add(new JLabel("File name: ")); fileNameComboBox = ComponentUtils.adjustComboForFileName(new JComboBox()); row2.add(fileNameComboBox.getComponent()); scopeSettingsPanel = ComponentUtils.adjustPanelForOptions(new JPanel(), false, fileNameComboBox); row3.add(new JLabel("Scope: ")); scopeComboBox = ComponentUtils.adjustComboForScope(new JComboBox(), null); row3.add(scopeComboBox.getComponent()); panel.add(row1); panel.add(row3); panel.add(row2); panel.add(scopeSettingsPanel.getComponent()); initChangeListener(); slider.addChangeListener(new ChangeListener() { @Override public void stateChanged(ChangeEvent e) { hoursLabel.setText(String.valueOf(slider.getValue())); } }); } return panel; } private void initChangeListener() { this.changeListener = new ChangeListener() { @Override public void stateChanged(ChangeEvent e) { fireChange(); } }; fileNameComboBox.addChangeListener(changeListener); scopeSettingsPanel.addChangeListener(changeListener); slider.addChangeListener(changeListener); } @Override public HelpCtx getHelpCtx() { return null; // Some help should be provided, omitted for simplicity. } /** * Create search composition for criteria specified in the form. */ @Override public SearchComposition<?> composeSearch() { SearchScopeOptions sso = scopeSettingsPanel.getSearchScopeOptions(); return new ExampleSearchComposition(sso, scopeComboBox.getSearchInfo(), slider.getValue(), this); } /** * Here we return always true, but could return false e.g. if file name * pattern is empty. */ @Override public boolean isUsable(NotificationLineSupport notifySupport) { return true; } } The last part of our search provider is the implementation of SearchComposition. This is a composition of various search parameters, the actual search algorithm, and the displayer that presents the results.Methods to implement: The most important method here is start, which performs the actual search. In this case, SearchInfo and SearchScopeOptions objects are used for traversing. These objects were provided by controllers of GUI components (in the presenter). When something interesting is found, it should be displayed (with SearchResultsDisplayer.addMatchingObject). Method getSearchResultsDisplayer should return the displayer associated with this composition. The displayer can be created by subclassing SearchResultsDisplayer class or simply by using the SearchResultsDisplayer.createDefault. Then you only need a helper object that can create nodes for found objects. Example file "org.netbeans.example.search.ExampleSearchComposition": package org.netbeans.example.search; public class ExampleSearchComposition extends SearchComposition<DataObject> { SearchScopeOptions searchScopeOptions; SearchInfo searchInfo; int oldInHours; SearchResultsDisplayer<DataObject> resultsDisplayer; private final Presenter presenter; AtomicBoolean terminated = new AtomicBoolean(false); public ExampleSearchComposition(SearchScopeOptions searchScopeOptions, SearchInfo searchInfo, int oldInHours, Presenter presenter) { this.searchScopeOptions = searchScopeOptions; this.searchInfo = searchInfo; this.oldInHours = oldInHours; this.presenter = presenter; } @Override public void start(SearchListener listener) { for (FileObject fo : searchInfo.getFilesToSearch( searchScopeOptions, listener, terminated)) { if (ageInHours(fo) < oldInHours) { try { DataObject dob = DataObject.find(fo); getSearchResultsDisplayer().addMatchingObject(dob); } catch (DataObjectNotFoundException ex) { listener.fileContentMatchingError(fo.getPath(), ex); } } } } @Override public void terminate() { terminated.set(true); } @Override public boolean isTerminated() { return terminated.get(); } /** * Use default displayer to show search results. */ @Override public synchronized SearchResultsDisplayer<DataObject> getSearchResultsDisplayer() { if (resultsDisplayer == null) { resultsDisplayer = createResultsDisplayer(); } return resultsDisplayer; } private SearchResultsDisplayer<DataObject> createResultsDisplayer() { /** * Object to transform matching objects to nodes. */ SearchResultsDisplayer.NodeDisplayer<DataObject> nd = new SearchResultsDisplayer.NodeDisplayer<DataObject>() { @Override public org.openide.nodes.Node matchToNode( final DataObject match) { return new FilterNode(match.getNodeDelegate()) { @Override public String getDisplayName() { return super.getDisplayName() + " (" + ageInMinutes(match.getPrimaryFile()) + " minutes old)"; } }; } }; return SearchResultsDisplayer.createDefault(nd, this, presenter, "less than " + oldInHours + " hours old"); } private static long ageInMinutes(FileObject fo) { long fileDate = fo.lastModified().getTime(); long now = System.currentTimeMillis(); return (now - fileDate) / 60000; } private static long ageInHours(FileObject fo) { return ageInMinutes(fo) / 60; } } Run the module, select a node in the Projects window, press Ctrl-F, and you'll see the "Find in Projects" dialog has two tabs, the second is the one you provided above:

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  • Matrix Multiplication with C++ AMP

    - by Daniel Moth
    As part of our API tour of C++ AMP, we looked recently at parallel_for_each. I ended that post by saying we would revisit parallel_for_each after introducing array and array_view. Now is the time, so this is part 2 of parallel_for_each, and also a post that brings together everything we've seen until now. The code for serial and accelerated Consider a naïve (or brute force) serial implementation of matrix multiplication  0: void MatrixMultiplySerial(std::vector<float>& vC, const std::vector<float>& vA, const std::vector<float>& vB, int M, int N, int W) 1: { 2: for (int row = 0; row < M; row++) 3: { 4: for (int col = 0; col < N; col++) 5: { 6: float sum = 0.0f; 7: for(int i = 0; i < W; i++) 8: sum += vA[row * W + i] * vB[i * N + col]; 9: vC[row * N + col] = sum; 10: } 11: } 12: } We notice that each loop iteration is independent from each other and so can be parallelized. If in addition we have really large amounts of data, then this is a good candidate to offload to an accelerator. First, I'll just show you an example of what that code may look like with C++ AMP, and then we'll analyze it. It is assumed that you included at the top of your file #include <amp.h> 13: void MatrixMultiplySimple(std::vector<float>& vC, const std::vector<float>& vA, const std::vector<float>& vB, int M, int N, int W) 14: { 15: concurrency::array_view<const float,2> a(M, W, vA); 16: concurrency::array_view<const float,2> b(W, N, vB); 17: concurrency::array_view<concurrency::writeonly<float>,2> c(M, N, vC); 18: concurrency::parallel_for_each(c.grid, 19: [=](concurrency::index<2> idx) restrict(direct3d) { 20: int row = idx[0]; int col = idx[1]; 21: float sum = 0.0f; 22: for(int i = 0; i < W; i++) 23: sum += a(row, i) * b(i, col); 24: c[idx] = sum; 25: }); 26: } First a visual comparison, just for fun: The beginning and end is the same, i.e. lines 0,1,12 are identical to lines 13,14,26. The double nested loop (lines 2,3,4,5 and 10,11) has been transformed into a parallel_for_each call (18,19,20 and 25). The core algorithm (lines 6,7,8,9) is essentially the same (lines 21,22,23,24). We have extra lines in the C++ AMP version (15,16,17). Now let's dig in deeper. Using array_view and extent When we decided to convert this function to run on an accelerator, we knew we couldn't use the std::vector objects in the restrict(direct3d) function. So we had a choice of copying the data to the the concurrency::array<T,N> object, or wrapping the vector container (and hence its data) with a concurrency::array_view<T,N> object from amp.h – here we used the latter (lines 15,16,17). Now we can access the same data through the array_view objects (a and b) instead of the vector objects (vA and vB), and the added benefit is that we can capture the array_view objects in the lambda (lines 19-25) that we pass to the parallel_for_each call (line 18) and the data will get copied on demand for us to the accelerator. Note that line 15 (and ditto for 16 and 17) could have been written as two lines instead of one: extent<2> e(M, W); array_view<const float, 2> a(e, vA); In other words, we could have explicitly created the extent object instead of letting the array_view create it for us under the covers through the constructor overload we chose. The benefit of the extent object in this instance is that we can express that the data is indeed two dimensional, i.e a matrix. When we were using a vector object we could not do that, and instead we had to track via additional unrelated variables the dimensions of the matrix (i.e. with the integers M and W) – aren't you loving C++ AMP already? Note that the const before the float when creating a and b, will result in the underling data only being copied to the accelerator and not be copied back – a nice optimization. A similar thing is happening on line 17 when creating array_view c, where we have indicated that we do not need to copy the data to the accelerator, only copy it back. The kernel dispatch On line 18 we make the call to the C++ AMP entry point (parallel_for_each) to invoke our parallel loop or, as some may say, dispatch our kernel. The first argument we need to pass describes how many threads we want for this computation. For this algorithm we decided that we want exactly the same number of threads as the number of elements in the output matrix, i.e. in array_view c which will eventually update the vector vC. So each thread will compute exactly one result. Since the elements in c are organized in a 2-dimensional manner we can organize our threads in a two-dimensional manner too. We don't have to think too much about how to create the first argument (a grid) since the array_view object helpfully exposes that as a property. Note that instead of c.grid we could have written grid<2>(c.extent) or grid<2>(extent<2>(M, N)) – the result is the same in that we have specified M*N threads to execute our lambda. The second argument is a restrict(direct3d) lambda that accepts an index object. Since we elected to use a two-dimensional extent as the first argument of parallel_for_each, the index will also be two-dimensional and as covered in the previous posts it represents the thread ID, which in our case maps perfectly to the index of each element in the resulting array_view. The kernel itself The lambda body (lines 20-24), or as some may say, the kernel, is the code that will actually execute on the accelerator. It will be called by M*N threads and we can use those threads to index into the two input array_views (a,b) and write results into the output array_view ( c ). The four lines (21-24) are essentially identical to the four lines of the serial algorithm (6-9). The only difference is how we index into a,b,c versus how we index into vA,vB,vC. The code we wrote with C++ AMP is much nicer in its indexing, because the dimensionality is a first class concept, so you don't have to do funny arithmetic calculating the index of where the next row starts, which you have to do when working with vectors directly (since they store all the data in a flat manner). I skipped over describing line 20. Note that we didn't really need to read the two components of the index into temporary local variables. This mostly reflects my personal choice, in some algorithms to break down the index into local variables with names that make sense for the algorithm, i.e. in this case row and col. In other cases it may i,j,k or x,y,z, or M,N or whatever. Also note that we could have written line 24 as: c(idx[0], idx[1])=sum  or  c(row, col)=sum instead of the simpler c[idx]=sum Targeting a specific accelerator Imagine that we had more than one hardware accelerator on a system and we wanted to pick a specific one to execute this parallel loop on. So there would be some code like this anywhere before line 18: vector<accelerator> accs = MyFunctionThatChoosesSuitableAccelerators(); accelerator acc = accs[0]; …and then we would modify line 18 so we would be calling another overload of parallel_for_each that accepts an accelerator_view as the first argument, so it would become: concurrency::parallel_for_each(acc.default_view, c.grid, ...and the rest of your code remains the same… how simple is that? Comments about this post by Daniel Moth welcome at the original blog.

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  • Low-level game engine renderer design

    - by Mark Ingram
    I'm piecing together the beginnings of an extremely basic engine which will let me draw arbitrary objects (SceneObject). I've got to the point where I'm creating a few sensible sounding classes, but as this is my first outing into game engines, I've got the feeling I'm overlooking things. I'm familiar with compartmentalising larger portions of the code so that individual sub-systems don't overly interact with each other, but I'm thinking more of the low-level stuff, starting from vertices working up. So if I have a Vertex class, I can combine that with a list of indices to make a Mesh class. How does the engine determine identical meshes for objects? Or is that left to the level designer? Once we have a Mesh, that can be contained in the SceneObject class. And a list of SceneObject can be placed into the Scene to be drawn. Right now I'm only using OpenGL, but I'm aware that I don't want to be tying OpenGL calls right in to base classes (such as updating the vertices in the Mesh, I don't want to be calling glBufferData etc). Are there any good resources that discuss these issues? Are there any "common" heirachies which should be used?

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  • Scene graphs and spatial partitioning structures: What do you really need?

    - by tapirath
    I've been fiddling with 2D games for awhile and I'm trying to go into 3D game development. I thought I should get my basics right first. From what I read scene graphs hold your game objects/entities and their relation to each other like 'a tire' would be the child of 'a vehicle'. It's mainly used for frustum/occlusion culling and minimizing the collision checks between the objects. Spatial partitioning structures on the other hand are used to divide a big game object (like the map) to smaller parts so that you can gain performance by only drawing the relevant polygons and again minimizing the collision checks to those polygons only. Also a spatial partitioning data structure can be used as a node in a scene graph. But... I've been reading about both subjects and I've seen a lot of "scene graphs are useless" and "BSP performance gain is irrelevant with modern hardware" kind of articles. Also some of the game engines I've checked like gameplay3d and jmonkeyengine are only using a scene graph (That also may be because they don't want to limit the developers). Whereas games like Quake and Half-Life only use spatial partitioning. I'm aware that the usage of these structures very much depend on the type of the game you're developing so for the sake of clarity let's assume the game is a FPS like Counter-Strike with some better outdoor environment capabilities (like a terrain). The obvious question is which one is needed and why (considering the modern hardware capabilities). Thank you.

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  • Understanding Box2d Restitution & Bouncing

    - by layzrr
    I'm currently trying to implement basketball bouncing into my game using Box2d (jBox2d technically), but I'm a bit confused about restitution. While trying to create the ball in the testbed first, I've run into infinite bouncing, as described in this question, however obviously not using my own implementation. The Box2d manual describes restitution as follows: Restitution is used to make objects bounce. The restitution value is usually set to be between 0 and 1. Consider dropping a ball on a table. A value of zero means the ball won't bounce. This is called an inelastic collision. A value of one means the ball's velocity will be exactly reflected. This is called a perfectly elastic collision. My confusion lies in that I am still getting infinite bouncing with restitution values at 0.75/0.8. The same behavior can be seen in the testbed under Collision Watching - Varying Restitution, on the 6th and 7th balls. I believe the last one has restitution of 1, which makes sense, but I don't understand why the second to last ball bounces infinitely (as is happening with my working basketball I've created). I am looking to understand the restitution concept more fully, as well as look for a solution to infinite bouncing with the Box2d framework. My instinct was to sleep objects that appeared to be moving in very small increments, but this seems like a misuse of the engine. Should I just work with lower restitution values altogether?

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  • Switch or a Dictionary when assigning to new object

    - by KChaloux
    Recently, I've come to prefer mapping 1-1 relationships using Dictionaries instead of Switch statements. I find it to be a little faster to write and easier to mentally process. Unfortunately, when mapping to a new instance of an object, I don't want to define it like this: var fooDict = new Dictionary<int, IBigObject>() { { 0, new Foo() }, // Creates an instance of Foo { 1, new Bar() }, // Creates an instance of Bar { 2, new Baz() } // Creates an instance of Baz } var quux = fooDict[0]; // quux references Foo Given that construct, I've wasted CPU cycles and memory creating 3 objects, doing whatever their constructors might contain, and only ended up using one of them. I also believe that mapping other objects to fooDict[0] in this case will cause them to reference the same thing, rather than creating a new instance of Foo as intended. A solution would be to use a lambda instead: var fooDict = new Dictionary<int, Func<IBigObject>>() { { 0, () => new Foo() }, // Returns a new instance of Foo when invoked { 1, () => new Bar() }, // Ditto Bar { 2, () => new Baz() } // Ditto Baz } var quux = fooDict[0](); // equivalent to saying 'var quux = new Foo();' Is this getting to a point where it's too confusing? It's easy to miss that () on the end. Or is mapping to a function/expression a fairly common practice? The alternative would be to use a switch: IBigObject quux; switch(someInt) { case 0: quux = new Foo(); break; case 1: quux = new Bar(); break; case 2: quux = new Baz(); break; } Which invocation is more acceptable? Dictionary, for faster lookups and fewer keywords (case and break) Switch: More commonly found in code, doesn't require the use of a Func< object for indirection.

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  • Does immutability entirely eliminate the need for locks in multi-processor programming?

    - by GlenPeterson
    Part 1 Clearly Immutability minimizes the need for locks in multi-processor programming, but does it eliminate that need, or are there instances where immutability alone is not enough? It seems to me that you can only defer processing and encapsulate state so long before most programs have to actually DO something. If a program performs actions on multiple processors, something needs to collect and aggregate the results. All this involves multi-process communication before, after, and possibly during some transformations. The start and end state of the machines are different. Can this always be done with no locks just by throwing out each object and creating a new one instead of changing the original (a crude view of immutability)? What cases still require locking? I'm interested in both the theoretical/academic answer and the practical/real-world answer. I know a lot of functional programmers like to talk about "no side effect" but in the "real world" everything has a side effect. Every processor click takes time and electricity and machine resources away from other processes. So I understand that there may be more than one perspective to answer this question from. If immutability is safe, given certain bounds or assumptions, I want to know what the borders of the "safety zone" are exactly. Some examples of possible boundaries: I/O Exceptions/errors Interfaces with programs written in other languages Interfaces with other machines (physical, virtual, or theoretical) Special thanks to @JimmaHoffa for his comment which started this question! Part 2 Multi-processor programming is often used as an optimization technique - to make some code run faster. When is it faster to use locks vs. immutable objects? Given the limits set out in Amdahl's Law, when can you achieve better over-all performance (with or without the garbage collector taken into account) with immutable objects vs. locking mutable ones? Summary I'm combining these two questions into one to try to get at where the bounding box is for Immutability as a solution to threading problems.

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  • What causes player box/world geometry glitches in old games?

    - by Alexander
    I'm looking to understand and find the terminology for what causes - or allows - players to interfere with geometry in old games. Famously, ID's Quake3 gave birth to a whole community of people breaking the physics by jumping, sliding, getting stuck and launching themselves off points in geometry. Some months ago (though I'd be darned if I can find it again!) I saw a conference held by Bungie's Vic DeLeon and a colleague in which Vic briefly discussed the issues he ran into while attempting to wrap 'collision' objects (please correct my terminology) around environment objects so that players could appear as though they were walking on organic surfaces, while not clipping through them or appear to be walking on air at certain points, due to complexities in the modeling. My aim is to compose a case study essay for University in which I can tackle this issue in games, drawing on early exploits and how techniques have changed to address such exploits and to aid in the gameplay itself. I have 3 current day example of where exploits still exist, however specifically targeting ID Software clearly shows they've massively improved their techniques between Q3 and Q4. So in summary, with your help please, I'd like to gain a slightly better understanding of this issue as a whole (its terminology mainly) so I can use terms and ask the right questions within the right contexts. In practical application, I know what it is, I know how to do it, but I don't have the benefit of level design knowledge yet and its technical widgety knick-knack terms =) Many thanks in advance AJ

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  • An alternative to multiple inheritance when creating an abstraction layer?

    - by sebf
    In my project I am creating an abstraction layer for some APIs. The purpose of the layer is to make multi-platform easier, and also to simplify the APIs to the feature set that I need while also providing some functionality, the implementation of which will be unique to each platform. At the moment, I have implemented it by defining and abstract class, which has methods which creates objects that implement interfaces. The abstract class and these interfaces define the capabilities of my abstraction layer. The implementation of these in my layer should of course be arbitrary from the POV view of my application, but I have done it, for my first API, by creating chains of subclasses which add more specific functionality as the features of the APIs they expose become less generic. An example would probably demonstrate this better: //The interface as seen by the application interface IGenericResource { byte[] GetSomeData(); } interface ISpecificResourceOne : IGenericResource { int SomePropertyOfResourceOne {get;} } interface ISpecificResourceTwo : IGenericResource { string SomePropertyOfResourceTwo {get;} } public abstract class MyLayer { ISpecificResourceOne CreateResourceOne(); ISpecificResourceTwo CreateResourceTwo(); void UseResourceOne(ISpecificResourceOne one); void UseResourceTwo(ISpecificResourceTwo two); } //The layer as created in my library public class LowLevelResource : IGenericResource { byte[] GetSomeData() {} } public class ResourceOne : LowLevelResource, ISpecificResourceOne { int SomePropertyOfResourceOne {get{}} } public class ResourceTwo : ResourceOne, ISpecificResourceTwo { string SomePropertyOfResourceTwo {get {}} } public partial class Implementation : MyLayer { override UseResourceOne(ISpecificResourceOne one) { DoStuff((ResourceOne)one); } } As can be seen, I am essentially trying to have two inheritance chains on the same object, but of course I can't do this so I simulate the second version with interfaces. The thing is though, I don't like using interfaces for this; it seems wrong, in my mind an interface defines a contract, any class that implements that interface should be able to be used where that interface is used but here that is clearly not the case because the interfaces are being used to allow an object from the layer to masquerade as something else, without the application needing to have access to its definition. What technique would allow me to define a comprehensive, intuitive collection of objects for an abstraction layer, while their implementation remains independent? (Language is C#)

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  • Strange and erratic transformations when using OpenGL VBOs to render scene

    - by janoside
    I have an existing iOS game with fairly simple scenes (all textured quads) and I'm using Apple's "Texture2D" class. I'm trying to convert this class to use VBOs since the vertices of my objects basically never change so I may as well not re-create them for every object every frame. I have the scene rendering using VBOs but the sizes and orientations of all rendered objects are strange and erratic - though locations seem generally correct. I've been toying with this code for a few days now, and I've found something odd: if I re-create all of my VBOs each frame, everything looks correct, even though I'm almost certain my vertices are not changing. Other notes I'm basing my work on this tutorial, and therefore am also using "IBOs" I create my buffers before rendering begins My buffers include vertex and texture data I'm using OpenGL ES 1.1 Fearing some strange effect of the current matrix GL state at the time of buffer creation I've also tried wrapping my buffer-setup code in a "pushMatrix-loadIdentity-popMatrix" block which (as expected) had no effect I'm aware that various articles have been published demonstrating that VBOs may not help performance, but I want to understand this problem and at least have the option to use them. I realize this is a shot in the dark, but has anyone else experienced this type of strange behavior? What might I be doing to result in this behavior? It's rather difficult for me to isolate the problem since I'm working in an existing, moderately complex project, so suggestions about how to approach the problem are also quite welcome.

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  • Adding 2D vector movement with rotation applied

    - by Michael Zehnich
    I am trying to apply a slight sine wave movement to objects that float around the screen to make them a little more interesting. I would like to apply this to the objects so that they oscillate from side to side, not front to back (so the oscillation does not affect their forward velocity). After reading various threads and tutorials, I have come to the conclusion that I need to create and add vectors, but I simply cannot come up with a solution that works. This is where I'm at right now, in the object's update method (updated based on comments): Vector2 oldPosition = new Vector2(spritePos.X, spritePos.Y); //note: newPosition is initially set in the constructor to spritePos.x/y Vector2 direction = newPosition - oldPosition; Vector2 perpendicular = new Vector2(direction.Y, -direction.X); perpendicular.Normalize(); sinePosAng += 0.1f; perpendicular.X += 2.5f * (float)Math.Sin(sinePosAng); spritePos.X += velocity * (float)Math.Cos(radians); spritePos.Y += velocity * (float)Math.Sin(radians); spritePos += perpendicular; newPosition = spritePos;

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  • cocos2d/OpenGL multitexturing problem

    - by Gajoo
    I've got a simple shader to test multitextureing the problem is both samplers are using same image as their reference. the shader code is basically just this : vec4 mid = texture2D(u_texture,v_texCoord); float g = texture2D(u_guide,v_guideCoord); gl_FragColor = vec4(g , mid.g,0,1); and this is how I'm calling draw function : int last_State; glGetIntegerv(GL_ACTIVE_TEXTURE, &last_State); glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, getTexture()->getName()); glActiveTexture(GL_TEXTURE1); glEnable(GL_TEXTURE_2D); glBindTexture(GL_TEXTURE_2D, mGuideTexture->getName()); ccGLEnableVertexAttribs( kCCVertexAttribFlag_TexCoords |kCCVertexAttribFlag_Position); glVertexAttribPointer(kCCVertexAttrib_Position, 2, GL_FLOAT, GL_FALSE, 0, vertices); glVertexAttribPointer(kCCVertexAttrib_TexCoords, 2, GL_FLOAT, GL_FALSE, 0, texCoord); glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); glDisable(GL_TEXTURE_2D); I've already check mGuideTexture->getName() and getTexture()->getName() are returning correct textures. but looking at the result I can tell, both samplers are reading from getTexture()->getName(). here are some screen shots showing what is happening : The image rendered Using above codes The image rendered when I change textures passed to samples I'm expecting to see green objects from the first picture with red objects hanging from the top.

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  • Why do memory-managed languages retain the `new` keyword?

    - by Channel72
    The new keyword in languages like Java, Javascript, and C# creates a new instance of a class. This syntax seems to have been inherited from C++, where new is used specifically to allocate a new instance of a class on the heap, and return a pointer to the new instance. In C++, this is not the only way to construct an object. You can also construct an object on the stack, without using new - and in fact, this way of constructing objects is much more common in C++. So, coming from a C++ background, the new keyword in languages like Java, Javascript, and C# seemed natural and obvious to me. Then I started to learn Python, which doesn't have the new keyword. In Python, an instance is constructed simply by calling the constructor, like: f = Foo() At first, this seemed a bit off to me, until it occurred to me that there's no reason for Python to have new, because everything is an object so there's no need to disambiguate between various constructor syntaxes. But then I thought - what's really the point of new in Java? Why should we say Object o = new Object();? Why not just Object o = Object();? In C++ there's definitely a need for new, since we need to distinguish between allocating on the heap and allocating on the stack, but in Java all objects are constructed on the heap, so why even have the new keyword? The same question could be asked for Javascript. In C#, which I'm much less familiar with, I think new may have some purpose in terms of distinguishing between object types and value types, but I'm not sure. Regardless, it seems to me that many languages which came after C++ simply "inherited" the new keyword - without really needing it. It's almost like a vestigial keyword. We don't seem to need it for any reason, and yet it's there. Question: Am I correct about this? Or is there some compelling reason that new needs to be in C++-inspired memory-managed languages like Java, Javascript and C#?

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  • Empty interface to combine multiple interfaces

    - by user1109519
    Suppose you have two interfaces: interface Readable { public void read(); } interface Writable { public void write(); } In some cases the implementing objects can only support one of these but in a lot of cases the implementations will support both interfaces. The people who use the interfaces will have to do something like: // can't write to it without explicit casting Readable myObject = new MyObject(); // can't read from it without explicit casting Writable myObject = new MyObject(); // tight coupling to actual implementation MyObject myObject = new MyObject(); None of these options is terribly convenient, even more so when considering that you want this as a method parameter. One solution would be to declare a wrapping interface: interface TheWholeShabam extends Readable, Writable {} But this has one specific problem: all implementations that support both Readable and Writable have to implement TheWholeShabam if they want to be compatible with people using the interface. Even though it offers nothing apart from the guaranteed presence of both interfaces. Is there a clean solution to this problem or should I go for the wrapper interface? UPDATE It is in fact often necessary to have an object that is both readable and writable so simply seperating the concerns in the arguments is not always a clean solution. UPDATE2 (extracted as answer so it's easier to comment on) UPDATE3 Please beware that the primary usecase for this is not streams (although they too must be supported). Streams make a very specific distinction between input and output and there is a clear separation of responsibilities. Rather, think of something like a bytebuffer where you need one object you can write to and read from, one object that has a very specific state attached to it. These objects exist because they are very useful for some things like asynchronous I/O, encodings,...

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  • Composing programs from small simple pieces: OOP vs Functional Programming

    - by Jay Godse
    I started programming when imperative programming languages such as C were virtually the only game in town for paid gigs. I'm not a computer scientist by training so I was only exposed to Assembler and Pascal in school, and not Lisp or Prolog. Over the 1990s, Object-Oriented Programming (OOP) became more popular because one of the marketing memes for OOP was that complex programs could be composed of loosely coupled but well-defined, well-tested, cohesive, and reusable classes and objects. And in many cases that is quite true. Once I learned object-oriented programming my C programs became better because I structured them more like classes and objects. In the last few years (2008-2014) I have programmed in Ruby, an OOP language. However, Ruby has many functional programming (FP) features such as lambdas and procs, which enable a different style of programming using recursion, currying, lazy evaluation and the like. (Through ignorance I am at a loss to explain why these techniques are so great). Very recently, I have written code to use methods from the Ruby Enumerable library, such as map(), reduce(), and select(). Apparently this is a functional style of programming. I have found that using these methods significantly reduce code volume, and make my code easier to debug. Upon reading more about FP, one of the marketing claims made by advocates is that FP enables developers to compose programs out of small well-defined, well-tested, and reusable functions, which leads to less buggy code, and low code volume. QUESTIONS: Is the composition of complex program by using FP techniques contradictory to or complementary to composition of a complex program by using OOP techniques? In which situations is OOP more effective, and when is FP more effective? Is it possible to use both techniques in the same complex program? Do the techniques overlap or contradict each other?

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  • Oracle Identity Manager ADF Customization

    - by Arda Eralp
    This blog entry includes an example about customization Oracle Identity Manager (OIM) Self Service screen. Before customization all users that can be logged in OIM Self Service can see "Administration" tab on left menu. On this example we create "Managers" role and only users that have managers role can see "Administration" tab. Step 1: Create "Manager" role  Step 2: Create Sandbox  Step 3: Customize ADF Select "Customize" on the top menu Select "Source" instead of "Design" on top  Select "Administration" tab with blue rectangle and edit component Edit "visible" with expression builder #{oimcontext.currentUser.roles['Manager'] != null} Apply Step 4: Apply to All and Publish sandbox Notes:  This table objects can use for expression. Objects Description #{oimcontext.currentUser['ATTRIBUTE_NAME']} #{oimcontext.currentUser['UDF_NAME']} #{oimcontext.currentUser.roles} #{oimcontext.currentUser.roles['SYSTEM ADMINISTRATORS'] != null} Boolean #{oimcontext.currentUser.adminRoles['OrclOIMSystemAdministrator'] != null} Boolean

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  • Platform game collisions with Block

    - by Sri Harsha Chilakapati
    I am trying to create a platform game and doing wrong collision detection with the blocks. Here's my code // Variables GTimer jump = new GTimer(1000); boolean onground = true; // The update method public void update(long elapsedTime){ MapView.follow(this); // Add the gravity if (!onground && !jump.active){ setVelocityY(4); } // Jumping if (isPressed(VK_SPACE) && onground){ jump.start(); setVelocityY(-4); onground = false; } if (jump.action(elapsedTime)){ // jump expired jump.stop(); } // Horizontal movement setVelocityX(0); if (isPressed(VK_LEFT)){ setVelocityX(-4); } if (isPressed(VK_RIGHT)){ setVelocityX(4); } } // The collision method public void collision(GObject other){ if (other instanceof Block){ // Determine the horizontal distance between centers float h_dist = Math.abs((other.getX() + other.getWidth()/2) - (getX() + getWidth()/2)); // Now the vertical distance float v_dist = Math.abs((other.getY() + other.getHeight()/2) - (getY() + getHeight()/2)); // If h_dist > v_dist horizontal collision else vertical collision if (h_dist > v_dist){ // Are we moving right? if (getX()<other.getX()){ setX(other.getX()-getWidth()); } // Are we moving left? else if (getX()>other.getX()){ setX(other.getX()+other.getWidth()); } } else { // Are we moving up? if (jump.active){ jump.stop(); } // We are moving down else { setY(other.getY()-getHeight()); setVelocityY(0); onground = true; } } } } The problem is that the object jumps well but does not fall when moved out of platform. Here's an image describing the problem. I know I'm not checking underneath the object but I don't know how. The map is a list of objects and should I have to iterate over all the objects??? Thanks

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  • Best Architecture for ASP.NET WebForms Application

    - by stack man
    I have written an ASP.NET WebForms portal for a client. The project has kind of evolved rather than being properly planned and structured from the beginning. Consequently, all the code is mashed together within the same project and without any layers. The client is now happy with the functionality, so I would like to refactor the code such that I will be confident about releasing the project. As there seems to be many differing ways to design the architecture, I would like some opinions about the best approach to take. FUNCTIONALITY The portal allows administrators to configure HTML templates. Other associated "partners" will be able to display these templates by adding IFrame code to their site. Within these templates, customers can register and purchase products. An API has been implemented using WCF allowing external companies to interface with the system also. An Admin section allows Administrators to configure various functionality and view reports for each partner. The system sends out invoices and email notifications to customers. CURRENT ARCHITECTURE It is currently using EF4 to read/write to the database. The EF objects are used directly within the aspx files. This has facilitated rapid development while I have been writing the site but it is probably unacceptable to keep it like that as it is tightly coupling the db with the UI. Specific business logic has been added to partial classes of the EF objects. QUESTIONS The goal of refactoring will be to make the site scalable, easily maintainable and secure. 1) What kind of architecture would be best for this? Please describe what should be in each layer, whether I should use DTO's / POCO / Active Record pattern etc. 2) Is there a robust way to auto-generate DTO's / BOs so that any future enhancements will be simple to implement despite the extra layers? 3) Would it be beneficial to convert the project from WebForms to MVC?

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  • Using a Vertex Buffer and DrawUserIndexedPrimitives?

    - by MattMcg
    Let's say I have a large but static world and only a single moving object on said world. To increase performance I wish to use a vertex and index buffer for the static part of the world. I set them up and they work fine however if I throw in another draw call to DrawUserIndexedPrimitives (to draw my one single moving object) after the call to DrawIndexedPrimitives, it will error out saying a valid vertex buffer must be set. I can only assume the DrawUserIndexedPrimitive call destroyed/replaced the vertex buffer I set. In order to get around this I must call device.SetVertexBuffer(vertexBuffer) every frame. Something tells me that isn't correct as that kind of defeats the point of a buffer? To shed some light, the large vertex buffer is the final merged mesh of many repeated cubes (think Minecraft) which I manually create to reduce the amount of vertices/indexes needed (for example two connected cubes become one cuboid, the connecting faces are cut out), and also the amount of matrix translations (as it would suck to do one per cube). The moving objects would be other items in the world which are dynamic and not fixed to the block grid, so things like the NPCs who move constantly. How do I go about handling the large static world but also allowing objects to freely move about?

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  • Multiplayer online game engine/pipeline

    - by Slav
    I am implementing online multiplayer game where client must be written in AS3 (Flash) to embed game into browser and server in C++ (abstract part of which is already written and used with other games). Networking models may differ from each other, but currently I'm looking toward game's logic run on both client and server parts but they're written on different languages while it's not the main problem. My previous game (pretty big one - was implemented with efforts of ~5 programmers in 1.5 years) was mainly "written" within electronic tables as structured objects with implemented inheritance: was written standalone tool which generated AS3 and C++ (languages of platforms to which the game was published) using specified electronic tables file (.xls or .ods). That file contained ~50 tables with ~50 rows and ~50 columns each and was mainly written by game designers which do not know any programming languages. But that game was single-player. Having declared problem with my currently implementing MMO, I'm looking toward some vast pipeline, where will be resolved such problems like: game objects descriptions (which starships exist within game, how much HP they have, how fast move, what damage deal...) actions descriptions (what players or NPCs can do: attack each other, collect resources, build structures, move, teleport, cast spells) - actions are transmitted through server between clients influences (what happens when specified action applied on specified object, e.i "Ship A attacked Ship B: field "HP" of Ship B reduced by amount of field "damage" of Ship A" Influences can be much more difficult, yes, e.i. "damage is twice it's size when Ship has =5 allies around him in a 200 units range during night" and so on. If to be able to write such logic within some "design document" it will be easily possible to: let designers to do their job without programmer's intervention or any bug-prone programming validate described logic transfer (transform, convert) to any programming language where it will be executed Did somebody worked on something like that? Is there some tools/engines/pipelines which concernes with it? How to handle all of this problems simultaneously in a best way or do I properly imagine my tasks and problems to myself?

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  • XNA hlsl tex2D() only reads 3 channels from normal maps and specular maps

    - by cubrman
    Our engine uses deferred rendering and at the main draw phase gathers plenty of data from the objects it draws. In order to save on tex2D calls, we packed our objects' specular maps with all sorts of data, so three out of four channels are already taken. To make it clear: I am talking about the assets that come with the models and are stored in their material's Specular Level channel, not about the RenderTarget. So now I need another information to be stored in the alpha channel, but I cannot make the shader to read it properly! Nomatter what I write into alpha it ends up being 1 (255)! I tried: saving the textures in PNG/TGA formats. turning off pre-computed alpha in model's properties. Out of every texture available to me (we use Diffuse map, Normal Map and Specular Map) I was only able to read alpha successfully from the Diffuse Map! Here is how I add specular and normal maps to my model's material in the content processor: if (geometry.Material.Textures.ContainsKey(normalMapKey)) { ExternalReference<TextureContent> texRef = geometry.Material.Textures[normalMapKey]; geometry.Material.Textures.Remove("NormalMap"); geometry.Material.Textures.Add("NormalMap", texRef); } ... foreach (KeyValuePair<String, ExternalReference<TextureContent>> texture in material.Textures) { if ((texture.Key == "Texture") || (texture.Key == "NormalMap") || (texture.Key == "SpecularMap")) mat.Textures.Add(texture.Key, texture.Value); } In the shader I obviously use: float4 data = tex2D(specularMapSampler, TexCoords); so data.a is always 1 in my case, could you suggest a reason?

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  • 2D Side scroller collision detection

    - by Shanon Simmonds
    I am trying to do some collision detection between objects and tiles, but the tiles do not have there own x and y position, they are just rendered to the x and y position given, there is an array of integers which has the ids of the tiles to use(which are given from an image and all the different colors are assigned different tiles) int x0 = camera.x / 16; int y0 = camera.y / 16; int x1 = (camera.x + screen.width) / 16; int y1 = (camera.y + screen.height) / 16; for(int y = y0; y < y1; y++) { if(y < 0 || y >= height) continue; // height is the height of the level for(int x = x0; x < x1; x++) { if(x < 0 || x >= width) continue; // width is the width of the level getTile(x, y).render(screen, x * 16, y * 16); } } I tried using the levels getTile method to see if the tile that the object was going to advance to, to see if it was a certain tile, but, it seems to only work in some directions. Any ideas on what I'm doing wrong and fixes would be greatly appreciated. What's wrong is that it doesn't collide properly in every direction and also this is how I tested for a collision in the objects class if(!level.getTile((x + xa) / 16, (y + ya) / 16).isSolid()) { x += xa; y += ya; } EDIT: xa and ya represent the direction as well as the movement, if xa is negative it means the object is moving left, if its positive it is moving right, and same with ya except negative for up, positive for down.

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  • Tiled Editor: How is this Map Handling Collision?

    - by user2736286
    BrowserQuest map in question. From what I understand, with tiled, there are two main ways to specify collision: Create an object layer, and interpret the shapes in the engine as collision objects. Create a tiled layer, and make all tiles in the layer have a collision property, and interpret all tiles in the layer as collision objects. I'm using BrowserQuest as a big source of inspiration for my project, and I want to know how they handled collision on the level editing side. I've checked through all their layers, expecting an object layer to be handling cliff collision like: But there are no such object layers to be found. Furthermore, the tile layers containing the tiles for such cliffs have no properties at all, meaning that they didn't just specify "collision" for such tile layers. I especially need to know how they handled less rectangular shapes like: I could imagine that they are not using explicit collision layers, but instead determining collision in the actual engine, based off the presence of specific tile layer sprites. Only because BrowserQuest has whole-tile movement, and it wouldn't look too odd if a small apple, taking up only a fraction of the tile size, prevents movement over that entire tile. But I'm creating a game with more precise movement, so collision has to be tight to the apple, and I really want to know how BrowserQuest approached collision defining. If anyone knowledgeable with Tiled could take a quick look at the map, I'd appreciate it! I'm tearing my hair out here :). Thanks

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  • Turn Based Event Algorithm

    - by GamersIncoming
    I'm currently working on a small roguelike in XNA, which sees the player in a randomly generated series of dungeons fending off creeps, as you might expect. As with most roguelikes, the player makes a move, and then each of the creeps currently active on screen will make a move in turns, until all creeps have updated, and it return's to the player's go. On paper, the simple algorithm is straightforward: Player takes turn Turn Number increments For each active creep, update Position Once all active creeps have updated, allow player to take next turn However, when it comes to actually writing this in more detail, the concept becomes a bit more tricky for me. So my question comes as this: what is the best way to handle events taking turns to trigger, where the completion of each last event triggers the next, when dealing with a large number of creeps (probably stored as an array of an enemy object), and is there an easier way to create some kind of engine that just takes all objects that need updating and chains them together so their updates follow suit? I'm not asking for code, just algorithms and theory in the direction of objects triggering updates one after the other, in a turn based manner. Thanks in advance. Edited: Here's the code I currently have that is horrible :/ if (player.getTurnOver() && updateWait == 0) { if (creep[creepToUpdate].getActive()) { creep[creepToUpdate].moveObject(player, map1); updateWait = 10; } if (creepToUpdate < creep.Length -1) { creepToUpdate++; } else { creepToUpdate = 0; player.setTurnOver(false); } } if (updateWait > 0) { updateWait--; }

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  • Do you tend to write your own name or your company name in your code?

    - by Connell Watkins
    I've been working on various projects at home and at work, and over the years I've developed two main APIs that I use in almost all AJAX based websites. I've compiled both of these into DLLs and called the namespaces Connell.Database and Connell.Json. My boss recently saw these namespaces in a software documentation for a project for the company and said I shouldn't be using my own name in the code. (But it's my code!) One thing to bear in mind is that we're not a software company. We're an IT support company, and I'm the only full-time software developer here, so there's not really any procedures on how we should write software in the company. Another thing to bear in mind is that I do intend on one day releasing these DLLs as open-source projects. How do other developers group their namespaces within their company? Does anyone use the same class libraries in personal and in work projects? Also does this work the other way round? If I write a class library entirely at work, who owns that code? If I've seen the library through from start to finish, designed it and programmed it. Can I use that for another project at home? Thanks, Update I've spoken to my boss about this issue and he agrees that they're my objects and he's fine for me to open-source them. Before this conversation I started changing the objects anyway, which was actually quite productive and the code now suits this specific project more-so than it did previously. But thank you to everyone involved for a very interesting debate. I hope all this text isn't wasted and someone learns from it. I certainly did. Cheers,

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