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  • Using a WPF ListView as a DataGrid

    - by psheriff
    Many people like to view data in a grid format of rows and columns. WPF did not come with a data grid control that automatically creates rows and columns for you based on the object you pass it. However, the WPF Toolkit can be downloaded from CodePlex.com that does contain a DataGrid control. This DataGrid gives you the ability to pass it a DataTable or a Collection class and it will automatically figure out the columns or properties and create all the columns for you and display the data.The DataGrid control also supports editing and many other features that you might not always need. This means that the DataGrid does take a little more time to render the data. If you want to just display data (see Figure 1) in a grid format, then a ListView works quite well for this task. Of course, you will need to create the columns for the ListView, but with just a little generic code, you can create the columns on the fly just like the WPF Toolkit’s DataGrid. Figure 1: A List of Data using a ListView A Simple ListView ControlThe XAML below is what you would use to create the ListView shown in Figure 1. However, the problem with using XAML is you have to pre-define the columns. You cannot re-use this ListView except for “Product” data. <ListView x:Name="lstData"          ItemsSource="{Binding}">  <ListView.View>    <GridView>      <GridViewColumn Header="Product ID"                      Width="Auto"               DisplayMemberBinding="{Binding Path=ProductId}" />      <GridViewColumn Header="Product Name"                      Width="Auto"               DisplayMemberBinding="{Binding Path=ProductName}" />      <GridViewColumn Header="Price"                      Width="Auto"               DisplayMemberBinding="{Binding Path=Price}" />    </GridView>  </ListView.View></ListView> So, instead of creating the GridViewColumn’s in XAML, let’s learn to create them in code to create any amount of columns in a ListView. Create GridViewColumn’s From Data TableTo display multiple columns in a ListView control you need to set its View property to a GridView collection object. You add GridViewColumn objects to the GridView collection and assign the GridView to the View property. Each GridViewColumn object needs to be bound to a column or property name of the object that the ListView will be bound to. An ADO.NET DataTable object contains a collection of columns, and these columns have a ColumnName property which you use to bind to the GridViewColumn objects. Listing 1 shows a sample of reading and XML file into a DataSet object. After reading the data a GridView object is created. You can then loop through the DataTable columns collection and create a GridViewColumn object for each column in the DataTable. Notice the DisplayMemberBinding property is set to a new Binding to the ColumnName in the DataTable. C#private void FirstSample(){  // Read the data  DataSet ds = new DataSet();  ds.ReadXml(GetCurrentDirectory() + @"\Xml\Product.xml");    // Create the GridView  GridView gv = new GridView();   // Create the GridView Columns  foreach (DataColumn item in ds.Tables[0].Columns)  {    GridViewColumn gvc = new GridViewColumn();    gvc.DisplayMemberBinding = new Binding(item.ColumnName);    gvc.Header = item.ColumnName;    gvc.Width = Double.NaN;    gv.Columns.Add(gvc);  }   // Setup the GridView Columns  lstData.View = gv;  // Display the Data  lstData.DataContext = ds.Tables[0];} VB.NETPrivate Sub FirstSample()  ' Read the data  Dim ds As New DataSet()  ds.ReadXml(GetCurrentDirectory() & "\Xml\Product.xml")   ' Create the GridView  Dim gv As New GridView()   ' Create the GridView Columns  For Each item As DataColumn In ds.Tables(0).Columns    Dim gvc As New GridViewColumn()    gvc.DisplayMemberBinding = New Binding(item.ColumnName)    gvc.Header = item.ColumnName    gvc.Width = [Double].NaN    gv.Columns.Add(gvc)  Next   ' Setup the GridView Columns  lstData.View = gv  ' Display the Data  lstData.DataContext = ds.Tables(0)End SubListing 1: Loop through the DataTable columns collection to create GridViewColumn objects A Generic Method for Creating a GridViewInstead of having to write the code shown in Listing 1 for each ListView you wish to create, you can create a generic method that given any DataTable will return a GridView column collection. Listing 2 shows how you can simplify the code in Listing 1 by setting up a class called WPFListViewCommon and create a method called CreateGridViewColumns that returns your GridView. C#private void DataTableSample(){  // Read the data  DataSet ds = new DataSet();  ds.ReadXml(GetCurrentDirectory() + @"\Xml\Product.xml");   // Setup the GridView Columns  lstData.View =      WPFListViewCommon.CreateGridViewColumns(ds.Tables[0]);  lstData.DataContext = ds.Tables[0];} VB.NETPrivate Sub DataTableSample()  ' Read the data  Dim ds As New DataSet()  ds.ReadXml(GetCurrentDirectory() & "\Xml\Product.xml")   ' Setup the GridView Columns  lstData.View = _      WPFListViewCommon.CreateGridViewColumns(ds.Tables(0))  lstData.DataContext = ds.Tables(0)End SubListing 2: Call a generic method to create GridViewColumns. The CreateGridViewColumns MethodThe CreateGridViewColumns method will take a DataTable as a parameter and create a GridView object with a GridViewColumn object in its collection for each column in your DataTable. C#public static GridView CreateGridViewColumns(DataTable dt){  // Create the GridView  GridView gv = new GridView();  gv.AllowsColumnReorder = true;   // Create the GridView Columns  foreach (DataColumn item in dt.Columns)  {    GridViewColumn gvc = new GridViewColumn();    gvc.DisplayMemberBinding = new Binding(item.ColumnName);    gvc.Header = item.ColumnName;    gvc.Width = Double.NaN;    gv.Columns.Add(gvc);  }   return gv;} VB.NETPublic Shared Function CreateGridViewColumns _  (ByVal dt As DataTable) As GridView  ' Create the GridView  Dim gv As New GridView()  gv.AllowsColumnReorder = True   ' Create the GridView Columns  For Each item As DataColumn In dt.Columns    Dim gvc As New GridViewColumn()    gvc.DisplayMemberBinding = New Binding(item.ColumnName)    gvc.Header = item.ColumnName    gvc.Width = [Double].NaN    gv.Columns.Add(gvc)  Next   Return gvEnd FunctionListing 3: The CreateGridViewColumns method takes a DataTable and creates GridViewColumn objects in a GridView. By separating this method out into a class you can call this method anytime you want to create a ListView with a collection of columns from a DataTable. SummaryIn this blog you learned how to create a ListView that acts like a DataGrid. You are able to use a DataTable as both the source of the data, and for creating the columns for the ListView. In the next blog entry you will learn how to use the same technique, but for Collection classes. NOTE: You can download the complete sample code (in both VB and C#) at my website. http://www.pdsa.com/downloads. Choose Tips & Tricks, then "WPF ListView as a DataGrid" from the drop-down. Good Luck with your Coding,Paul Sheriff ** SPECIAL OFFER FOR MY BLOG READERS **Visit http://www.pdsa.com/Event/Blog for a free eBook on "Fundamentals of N-Tier".

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  • Mapping a Vertex Buffer in DirectX11

    - by judeclarke
    I have a VertexBuffer that I am remapping on a per frame base for a bunch of quads that are constantly updated, sharing the same material\index buffer but have different width/heights. However, currently right now there is a really bad flicker on this geometry. Although it is flickering, the flicker looks correct. I know it is the vertex buffer mapping because if I recreate the entire VB then it will render fine. However, as an optimization I figured I would just remap it. Does anyone know what the problem is? The length (width, size) of the vertex buffer is always the same. One might think it is double buffering, however, it would not be double buffering because it only happens when I map/unmap the buffer, so that leads me to believe that I am setting some parameters wrong on the creation or mapping. I am using DirectX11, my initialization and remap code are: Initialization code D3D11_BUFFER_DESC bd; ZeroMemory( &bd, sizeof(bd) ); bd.Usage = D3D11_USAGE_DYNAMIC; bd.ByteWidth = vertCount * vertexTypeWidth; bd.BindFlags = D3D11_BIND_VERTEX_BUFFER; //bd.CPUAccessFlags = 0; bd.CPUAccessFlags = D3D11_CPU_ACCESS_WRITE; D3D11_SUBRESOURCE_DATA InitData; ZeroMemory( &InitData, sizeof(InitData) ); InitData.pSysMem = vertices; mVertexType = vertexType; HRESULT hResult = device->CreateBuffer( &bd, &InitData, &m_pVertexBuffer ); // This will be S_OK if(hResult != S_OK) return false; Remap code D3D11_MAPPED_SUBRESOURCE resource; HRESULT hResult = deviceContext->Map(m_pVertexBuffer, 0, D3D11_MAP_WRITE_DISCARD, 0, &resource); // This will be S_OK if(hResult != S_OK) return false; resource.pData = vertices; deviceContext->Unmap(m_pVertexBuffer, 0);

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  • Integrate Bing Search API into ASP.Net application

    - by sreejukg
    Couple of months back, I wrote an article about how to integrate Bing Search engine (API 2.0) with ASP.Net website. You can refer the article here http://weblogs.asp.net/sreejukg/archive/2012/04/07/integrate-bing-api-for-search-inside-asp-net-web-application.aspx Things are changing rapidly in the tech world and Bing has also changed! The Bing Search API 2.0 will work until August 1, 2012, after that it will not return results. Shocked? Don’t worry the API has moved to Windows Azure market place and available for you to sign up and continue using it and there is a free version available based on your usage. In this article, I am going to explain how you can integrate the new Bing API that is available in the Windows Azure market place with your website. You can access the Windows Azure market place from the below link https://datamarket.azure.com/ There is lot of applications available for you to subscribe and use. Bing is one of them. You can find the new Bing Search API from the below link https://datamarket.azure.com/dataset/5BA839F1-12CE-4CCE-BF57-A49D98D29A44 To get access to Bing Search API, first you need to register an account with Windows Azure market place. Sign in to the Windows Azure market place site using your windows live account. Once you sign in with your windows live account, you need to register to Windows Azure Market place account. From the Windows Azure market place, you will see the sign in button it the top right of the page. Clicking on the sign in button will take you to the Windows live ID authentication page. You can enter a windows live ID here to login. Once logged in you will see the Registration page for the Windows Azure market place as follows. You can agree or disagree for the email address usage by Microsoft. I believe selecting the check box means you will get email about what is happening in Windows Azure market place. Click on continue button once you are done. In the next page, you should accept the terms of use, it is not optional, you must agree to terms and conditions. Scroll down to the page and select the I agree checkbox and click on Register Button. Now you are a registered member of Windows Azure market place. You can subscribe to data applications. In order to use BING API in your application, you must obtain your account Key, in the previous version of Bing you were required an API key, the current version uses Account Key instead. Once you logged in to the Windows Azure market place, you can see “My Account” in the top menu, from the Top menu; go to “My Account” Section. From the My Account section, you can manage your subscriptions and Account Keys. Account Keys will be used by your applications to access the subscriptions from the market place. Click on My Account link, you can see Account Keys in the left menu and then Add an account key or you can use the default Account key available. Creating account key is very simple process. Also you can remove the account keys you create if necessary. The next step is to subscribe to BING Search API. At this moment, Bing Offers 2 APIs for search. The available options are as follows. 1. Bing Search API - https://datamarket.azure.com/dataset/5ba839f1-12ce-4cce-bf57-a49d98d29a44 2. Bing Search API – Web Results only - https://datamarket.azure.com/dataset/8818f55e-2fe5-4ce3-a617-0b8ba8419f65 The difference is that the later will give you only web results where the other you can specify the source type such as image, video, web, news etc. Carefully choose the API based on your application requirements. In this article, I am going to use Web Results Only API, but the steps will be similar to both. Go to the API page https://datamarket.azure.com/dataset/8818f55e-2fe5-4ce3-a617-0b8ba8419f65, you can see the subscription options in the right side. And in the bottom of the page you can see the free option Since I am going to use the free options, just Click the Sign Up link for that. Just select I agree check box and click on the Sign Up button. You will get a recipt pagethat detail your subscription. Now you are ready Bing Search API – Web results. The next step is to integrate the API into your ASP.Net application. Now if you go to the Search API page (as well as in the Receipt page), you can see a .Net C# Class Library link, click on the link, you will get a code file named “BingSearchContainer.cs”. In the following sections I am going to demonstrate the use of Bing Search API from an ASP.Net application. Create an empty ASP.Net web application. In the solution explorer, the application will looks as follows. Now add the downloaded code file (“BingSearchContainer.cs”) to the project. Right click your project in solution explorer, Add -> existing item, then browse to the downloaded location, select the “BingSearchContainer.cs” file and add it to the project. To build the code file you need to add reference to the following library. System.Data.Services.Client You can find the library in the .Net tab, when you select Add -> Reference Try to build your project now; it should build without any errors. Add an ASP.Net page to the project. I have included a text box and a button, then a Grid View to the page. The idea is to Search the text entered and display the results in the gridview. The page will look in the Visual Studio Designer as follows. The markup of the page is as follows. In the button click event handler for the search button, I have used the following code. Now run your project and enter some text in the text box and click the Search button, you will see the results coming from Bing, cool. I entered the text “Microsoft” in the textbox and clicked on the button and I got the following results. Searching Specific Websites If you want to search a particular website, you pass the site url with site:<site url name> and if you have more sites, use pipe (|). e.g. The following search query site:microsoft.com | site:adobe.com design will search the word design and return the results from Microsoft.com and Adobe.com See the sample code that search only Microsoft.com for the text entered for the above sample. var webResults = bingContainer.Web("site:www.Microsoft.com " + txtSearch.Text, null, null, null, null, null, null); Paging the results returned by the API By default the BING API will return 100 results based on your query. The default code file that you downloaded from BING doesn’t include any option for this. You can modify the downloaded code to perform this paging. The BING API supports two parameters $top (for number of results to return) and $skip (for number of records to skip). So if you want 3rd page of results with page size = 10, you need to pass $top = 10 and $skip=20. Open the BingSearchContainer.cs in the editor. You can see the Web method in it as follows. public DataServiceQuery<WebResult> Web(String Query, String Market, String Adult, Double? Latitude, Double? Longitude, String WebFileType, String Options) {  In the method signature, I have added two more parameters public DataServiceQuery<WebResult> Web(String Query, String Market, String Adult, Double? Latitude, Double? Longitude, String WebFileType, String Options, int resultCount, int pageNo) { and in the method, you need to pass the parameters to the query variable. query = query.AddQueryOption("$top", resultCount); query = query.AddQueryOption("$skip", (pageNo -1)*resultCount); return query; Note that I didn’t perform any validation, but you need to check conditions such as resultCount and pageCount should be greater than or equal to 1. If the parameters are not valid, the Bing Search API will throw the error. The modified method is as follows. The changes are highlighted. Now see the following code in the SearchPage.aspx.cs file protected void btnSearch_Click(object sender, EventArgs e) {     var bingContainer = new Bing.BingSearchContainer(new Uri(https://api.datamarket.azure.com/Bing/SearchWeb/));     // replace this value with your account key     var accountKey = "your key";     // the next line configures the bingContainer to use your credentials.     bingContainer.Credentials = new NetworkCredential(accountKey, accountKey);     var webResults = bingContainer.Web("site:microsoft.com" +txtSearch.Text , null, null, null, null, null, null,3,2);     lstResults.DataSource = webResults;     lstResults.DataBind(); } The following code will return 3 results starting from second page (by skipping first 3 results). See the result page as follows. Bing provides complete integration to its offerings. When you develop search based applications, you can use the power of Bing to perform the search. Integrating Bing Search API to ASP.Net application is a simple process and without investing much time, you can develop a good search based application. Make sure you read the terms of use before designing the application and decide which API usage is suitable for you. Further readings BING API Migration Guide http://go.microsoft.com/fwlink/?LinkID=248077 Bing API FAQ http://go.microsoft.com/fwlink/?LinkID=252146 Bing API Schema Guide http://go.microsoft.com/fwlink/?LinkID=252151

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  • Adventures in MVVM &ndash; My ViewModel Base

    - by Brian Genisio's House Of Bilz
    More Adventures in MVVM First, I’d like to say: THIS IS NOT A NEW MVVM FRAMEWORK. I tend to believe that MVVM support code should be specific to the system you are building and the developers working on it.  I have yet to find an MVVM framework that does everything I want it to without doing too much.  Don’t get me wrong… there are some good frameworks out there.  I just like to pick and choose things that make sense for me.  I’d also like to add that some of these features only work in WPF.  As of Silveright 4, they don’t support binding to dynamic properties, so some of the capabilities are lost. That being said, I want to share my ViewModel base class with the world.  I have had several conversations with people about the problems I have solved using this ViewModel base.  A while back, I posted an article about some experiments with a “Rails Inspired ViewModel”.  What followed from those ideas was a ViewModel base class that I take with me and use in my projects.  It has a lot of features, all designed to reduce the friction in writing view models. I have put the code out on Codeplex under the project: ViewModelSupport. Finally, this article focuses on the ViewModel and only glosses over the View and the Model.  Without all three, you don’t have MVVM.  But this base class is for the ViewModel, so that is what I am focusing on. Features: Automatic Command Plumbing Property Change Notification Strongly Typed Property Getter/Setters Dynamic Properties Default Property values Derived Properties Automatic Method Execution Command CanExecute Change Notification Design-Time Detection What about Silverlight? Automatic Command Plumbing This feature takes the plumbing out of creating commands.  The common pattern for commands in a ViewModel is to have an Execute method as well as an optional CanExecute method.  To plumb that together, you create an ICommand Property, and set it in the constructor like so: Before public class AutomaticCommandViewModel { public AutomaticCommandViewModel() { MyCommand = new DelegateCommand(Execute_MyCommand, CanExecute_MyCommand); } public void Execute_MyCommand() { // Do something } public bool CanExecute_MyCommand() { // Are we in a state to do something? return true; } public DelegateCommand MyCommand { get; private set; } } With the base class, this plumbing is automatic and the property (MyCommand of type ICommand) is created for you.  The base class uses the convention that methods be prefixed with Execute_ and CanExecute_ in order to be plumbed into commands with the property name after the prefix.  You are left to be expressive with your behavior without the plumbing.  If you are wondering how CanExecuteChanged is raised, see the later section “Command CanExecute Change Notification”. After public class AutomaticCommandViewModel : ViewModelBase { public void Execute_MyCommand() { // Do something } public bool CanExecute_MyCommand() { // Are we in a state to do something? return true; } }   Property Change Notification One thing that always kills me when implementing ViewModels is how to make properties that notify when they change (via the INotifyPropertyChanged interface).  There have been many attempts to make this more automatic.  My base class includes one option.  There are others, but I feel like this works best for me. The common pattern (without my base class) is to create a private backing store for the variable and specify a getter that returns the private field.  The setter will set the private field and fire an event that notifies the change, only if the value has changed. Before public class PropertyHelpersViewModel : INotifyPropertyChanged { private string text; public string Text { get { return text; } set { if(text != value) { text = value; RaisePropertyChanged("Text"); } } } protected void RaisePropertyChanged(string propertyName) { var handlers = PropertyChanged; if(handlers != null) handlers(this, new PropertyChangedEventArgs(propertyName)); } public event PropertyChangedEventHandler PropertyChanged; } This way of defining properties is error-prone and tedious.  Too much plumbing.  My base class eliminates much of that plumbing with the same functionality: After public class PropertyHelpersViewModel : ViewModelBase { public string Text { get { return Get<string>("Text"); } set { Set("Text", value);} } }   Strongly Typed Property Getters/Setters It turns out that we can do better than that.  We are using a strongly typed language where the use of “Magic Strings” is often frowned upon.  Lets make the names in the getters and setters strongly typed: A refinement public class PropertyHelpersViewModel : ViewModelBase { public string Text { get { return Get(() => Text); } set { Set(() => Text, value); } } }   Dynamic Properties In C# 4.0, we have the ability to program statically OR dynamically.  This base class lets us leverage the powerful dynamic capabilities in our ecosystem. (This is how the automatic commands are implemented, BTW)  By calling Set(“Foo”, 1), you have now created a dynamic property called Foo.  It can be bound against like any static property.  The opportunities are endless.  One great way to exploit this behavior is if you have a customizable view engine with templates that bind to properties defined by the user.  The base class just needs to create the dynamic properties at runtime from information in the model, and the custom template can bind even though the static properties do not exist. All dynamic properties still benefit from the notifiable capabilities that static properties do. For any nay-sayers out there that don’t like using the dynamic features of C#, just remember this: the act of binding the View to a ViewModel is dynamic already.  Why not exploit it?  Get over it :) Just declare the property dynamically public class DynamicPropertyViewModel : ViewModelBase { public DynamicPropertyViewModel() { Set("Foo", "Bar"); } } Then reference it normally <TextBlock Text="{Binding Foo}" />   Default Property Values The Get() method also allows for default properties to be set.  Don’t set them in the constructor.  Set them in the property and keep the related code together: public string Text { get { return Get(() => Text, "This is the default value"); } set { Set(() => Text, value);} }   Derived Properties This is something I blogged about a while back in more detail.  This feature came from the chaining of property notifications when one property affects the results of another, like this: Before public class DependantPropertiesViewModel : ViewModelBase { public double Score { get { return Get(() => Score); } set { Set(() => Score, value); RaisePropertyChanged("Percentage"); RaisePropertyChanged("Output"); } } public int Percentage { get { return (int)(100 * Score); } } public string Output { get { return "You scored " + Percentage + "%."; } } } The problem is: The setter for Score has to be responsible for notifying the world that Percentage and Output have also changed.  This, to me, is backwards.    It certainly violates the “Single Responsibility Principle.” I have been bitten in the rear more than once by problems created from code like this.  What we really want to do is invert the dependency.  Let the Percentage property declare that it changes when the Score Property changes. After public class DependantPropertiesViewModel : ViewModelBase { public double Score { get { return Get(() => Score); } set { Set(() => Score, value); } } [DependsUpon("Score")] public int Percentage { get { return (int)(100 * Score); } } [DependsUpon("Percentage")] public string Output { get { return "You scored " + Percentage + "%."; } } }   Automatic Method Execution This one is extremely similar to the previous, but it deals with method execution as opposed to property.  When you want to execute a method triggered by property changes, let the method declare the dependency instead of the other way around. Before public class DependantMethodsViewModel : ViewModelBase { public double Score { get { return Get(() => Score); } set { Set(() => Score, value); WhenScoreChanges(); } } public void WhenScoreChanges() { // Handle this case } } After public class DependantMethodsViewModel : ViewModelBase { public double Score { get { return Get(() => Score); } set { Set(() => Score, value); } } [DependsUpon("Score")] public void WhenScoreChanges() { // Handle this case } }   Command CanExecute Change Notification Back to Commands.  One of the responsibilities of commands that implement ICommand – it must fire an event declaring that CanExecute() needs to be re-evaluated.  I wanted to wait until we got past a few concepts before explaining this behavior.  You can use the same mechanism here to fire off the change.  In the CanExecute_ method, declare the property that it depends upon.  When that property changes, the command will fire a CanExecuteChanged event, telling the View to re-evaluate the state of the command.  The View will make appropriate adjustments, like disabling the button. DependsUpon works on CanExecute methods as well public class CanExecuteViewModel : ViewModelBase { public void Execute_MakeLower() { Output = Input.ToLower(); } [DependsUpon("Input")] public bool CanExecute_MakeLower() { return !string.IsNullOrWhiteSpace(Input); } public string Input { get { return Get(() => Input); } set { Set(() => Input, value);} } public string Output { get { return Get(() => Output); } set { Set(() => Output, value); } } }   Design-Time Detection If you want to add design-time data to your ViewModel, the base class has a property that lets you ask if you are in the designer.  You can then set some default values that let your designer see what things might look like in runtime. Use the IsInDesignMode property public DependantPropertiesViewModel() { if(IsInDesignMode) { Score = .5; } }   What About Silverlight? Some of the features in this base class only work in WPF.  As of version 4, Silverlight does not support binding to dynamic properties.  This, in my opinion, is a HUGE limitation.  Not only does it keep you from using many of the features in this ViewModel, it also keeps you from binding to ViewModels designed in IronRuby.  Does this mean that the base class will not work in Silverlight?  No.  Many of the features outlined in this article WILL work.  All of the property abstractions are functional, as long as you refer to them statically in the View.  This, of course, means that the automatic command hook-up doesn’t work in Silverlight.  You need to plumb it to a static property in order for the Silverlight View to bind to it.  Can I has a dynamic property in SL5?     Good to go? So, that concludes the feature explanation of my ViewModel base class.  Feel free to take it, fork it, whatever.  It is hosted on CodePlex.  When I find other useful additions, I will add them to the public repository.  I use this base class every day.  It is mature, and well tested.  If, however, you find any problems with it, please let me know!  Also, feel free to suggest patches to me via the CodePlex site.  :)

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  • ScrollViewer.EnsureVisible for Windows Phone

    - by Daniel Moth
    In my Translator By Moth app, on both the current and saved pivot pages the need arose to programmatically scroll to the bottom. In the former, case it is when a translation takes place (if the text is too long, I want to scroll to the bottom of the translation so the user can focus on that, and not their input text for translation). In the latter case it was when a new translation is saved (it is added to the bottom of the list, so scrolling is required to make it visible). On both pages a ScrollViewer is used. In my exploration of the APIs through intellisense and msdn I could not find a method that auto scrolled to the bottom. So I hacked together a solution where I added a blank textblock to the bottom of each page (within the ScrollViewer, but above the translated textblock and the saved list) and tried to make it scroll it into view from code. After searching the web I found a little algorithm that did most of what I wanted (sorry, I do not have the reference handy, but thank you whoever it was) that after minor tweaking I turned into an extension method for the ScrollViewer that is very easy to use: this.Scroller.EnsureVisible(this.BlankText); The method itself I share with you here: public static void EnsureVisible(this System.Windows.Controls.ScrollViewer scroller, System.Windows.UIElement uiElem) { System.Diagnostics.Debug.Assert(scroller != null); System.Diagnostics.Debug.Assert(uiElem != null); scroller.UpdateLayout(); double maxScrollPos = scroller.ExtentHeight - scroller.ViewportHeight; double scrollPos = scroller.VerticalOffset - scroller.TransformToVisual(uiElem).Transform(new System.Windows.Point(0, 0)).Y; if (scrollPos > maxScrollPos) scrollPos = maxScrollPos; else if (scrollPos < 0) scrollPos = 0; scroller.ScrollToVerticalOffset(scrollPos); } I am sure there are better ways, but this "worked for me" :-) Comments about this post by Daniel Moth welcome at the original blog.

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  • What is Polymorphism?

    - by SAMIR BHOGAYTA
    * Polymorphism is one of the primary characteristics (concept) of object-oriented programming. * Poly means many and morph means form. Thus, polymorphism refers to being able to use many forms of a type without regard to the details. * Polymorphism is the characteristic of being able to assign a different meaning specifically, to allow an entity such as a variable, a function, or an object to have more than one form. * Polymorphism is the ability to process objects differently depending on their data types. * Polymorphism is the ability to redefine methods for derived classes. Types of Polymorphism * Compile time Polymorphism * Run time Polymorphism Compile time Polymorphism * Compile time Polymorphism also known as method overloading * Method overloading means having two or more methods with the same name but with different signatures Example of Compile time polymorphism public class Calculations { public int add(int x, int y) { return x+y; } public int add(int x, int y, int z) { return x+y+z; } } Run time Polymorphism * Run time Polymorphism also known as method overriding * Method overriding means having two or more methods with the same name , same signature but with different implementation Example of Run time Polymorphism class Circle { public int radius = 0; public double getArea() { return 3.14 * radius * radius } } class Sphere { public double getArea() { return 4 * 3.14 * radius * radius } }

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  • Loose Coupling in Object Oriented Design

    - by m3th0dman
    I am trying to learn GRASP and I found this explained (here on page 3) about Low Coupling and I was very surprised when I found this: Consider the method addTrack for an Album class, two possible methods are: addTrack( Track t ) and addTrack( int no, String title, double duration ) Which method reduces coupling? The second one does, since the class using the Album class does not have to know a Track class. In general, parameters to methods should use base types (int, char ...) and classes from the java.* packages. I tend to diasgree with this; I believe addTrack(Track t) is better than addTrack(int no, String title, double duration) due to various reasons: It is always better for a method to as fewer parameters as possible (according to Uncle Bob's Clean Code none or one preferably, 2 in some cases and 3 in special cases; more than 3 needs refactoring - these are of course recommendations not holly rules). If addTrack is a method of an interface, and the requirements need that a Track should have more information (say year or genre) then the interface needs to be changed and so that the method should supports another parameter. Encapsulation is broke; if addTrack is in an interface, then it should not know the internals of the Track. It is actually more coupled in the second way, with many parameters. Suppose the no parameter needs to be changed from int to long because there are more than MAX_INT tracks (or for whatever reason); then both the Track and the method need to be changed while if the method would be addTrack(Track track) only the Track would be changed. All the 4 arguments are actually connected with each other, and some of them are consequences from others. Which approach is better?

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  • exporting bind and keyframe bone poses from blender to use in OpenGL

    - by SaldaVonSchwartz
    I'm having a hard time trying to understand how exactly Blender's concept of bone transforms maps to the usual math of skinning (which I'm implementing in an OpenGL-based engine of sorts). Or I'm missing out something in the math.. It's gonna be long, but here's as much background as I can think of. First, a few notes and assumptions: I'm using column-major order and multiply from right to left. So for instance, vertex v transformed by matrix A and then further transformed by matrix B would be: v' = BAv. This also means whenever I export a matrix from blender through python, I export it (in text format) in 4 lines, each representing a column. This is so I can then I can read them back into my engine like this: if (fscanf(fileHandle, "%f %f %f %f", &skeleton.joints[currentJointIndex].inverseBindTransform.m[0], &skeleton.joints[currentJointIndex].inverseBindTransform.m[1], &skeleton.joints[currentJointIndex].inverseBindTransform.m[2], &skeleton.joints[currentJointIndex].inverseBindTransform.m[3])) { if (fscanf(fileHandle, "%f %f %f %f", &skeleton.joints[currentJointIndex].inverseBindTransform.m[4], &skeleton.joints[currentJointIndex].inverseBindTransform.m[5], &skeleton.joints[currentJointIndex].inverseBindTransform.m[6], &skeleton.joints[currentJointIndex].inverseBindTransform.m[7])) { if (fscanf(fileHandle, "%f %f %f %f", &skeleton.joints[currentJointIndex].inverseBindTransform.m[8], &skeleton.joints[currentJointIndex].inverseBindTransform.m[9], &skeleton.joints[currentJointIndex].inverseBindTransform.m[10], &skeleton.joints[currentJointIndex].inverseBindTransform.m[11])) { if (fscanf(fileHandle, "%f %f %f %f", &skeleton.joints[currentJointIndex].inverseBindTransform.m[12], &skeleton.joints[currentJointIndex].inverseBindTransform.m[13], &skeleton.joints[currentJointIndex].inverseBindTransform.m[14], &skeleton.joints[currentJointIndex].inverseBindTransform.m[15])) { I'm simplifying the code I show because otherwise it would make things unnecessarily harder (in the context of my question) to explain / follow. Please refrain from making remarks related to optimizations. This is not final code. Having said that, if I understand correctly, the basic idea of skinning/animation is: I have a a mesh made up of vertices I have the mesh model-world transform W I have my joints, which are really just transforms from each joint's space to its parent's space. I'll call these transforms Bj meaning matrix which takes from joint j's bind pose to joint j-1's bind pose. For each of these, I actually import their inverse to the engine, Bj^-1. I have keyframes each containing a set of current poses Cj for each joint J. These are initially imported to my engine in TQS format but after (S)LERPING them I compose them into Cj matrices which are equivalent to the Bjs (not the Bj^-1 ones) only that for the current spacial configurations of each joint at that frame. Given the above, the "skeletal animation algorithm is" On each frame: check how much time has elpased and compute the resulting current time in the animation, from 0 meaning frame 0 to 1, meaning the end of the animation. (Oh and I'm looping forever so the time is mod(total duration)) for each joint: 1 -calculate its world inverse bind pose, that is Bj_w^-1 = Bj^-1 Bj-1^-1 ... B0^-1 2 -use the current animation time to LERP the componets of the TQS and come up with an interpolated current pose matrix Cj which should transform from the joints current configuration space to world space. Similar to what I did to get the world version of the inverse bind poses, I come up with the joint's world current pose, Cj_w = C0 C1 ... Cj 3 -now that I have world versions of Bj and Cj, I store this joint's world- skinning matrix K_wj = Cj_w Bj_w^-1. The above is roughly implemented like so: - (void)update:(NSTimeInterval)elapsedTime { static double time = 0; time = fmod((time + elapsedTime),1.); uint16_t LERPKeyframeNumber = 60 * time; uint16_t lkeyframeNumber = 0; uint16_t lkeyframeIndex = 0; uint16_t rkeyframeNumber = 0; uint16_t rkeyframeIndex = 0; for (int i = 0; i < aClip.keyframesCount; i++) { uint16_t keyframeNumber = aClip.keyframes[i].number; if (keyframeNumber <= LERPKeyframeNumber) { lkeyframeIndex = i; lkeyframeNumber = keyframeNumber; } else { rkeyframeIndex = i; rkeyframeNumber = keyframeNumber; break; } } double lTime = lkeyframeNumber / 60.; double rTime = rkeyframeNumber / 60.; double blendFactor = (time - lTime) / (rTime - lTime); GLKMatrix4 bindPosePalette[aSkeleton.jointsCount]; GLKMatrix4 currentPosePalette[aSkeleton.jointsCount]; for (int i = 0; i < aSkeleton.jointsCount; i++) { F3DETQSType& lPose = aClip.keyframes[lkeyframeIndex].skeletonPose.jointPoses[i]; F3DETQSType& rPose = aClip.keyframes[rkeyframeIndex].skeletonPose.jointPoses[i]; GLKVector3 LERPTranslation = GLKVector3Lerp(lPose.t, rPose.t, blendFactor); GLKQuaternion SLERPRotation = GLKQuaternionSlerp(lPose.q, rPose.q, blendFactor); GLKVector3 LERPScaling = GLKVector3Lerp(lPose.s, rPose.s, blendFactor); GLKMatrix4 currentTransform = GLKMatrix4MakeWithQuaternion(SLERPRotation); currentTransform = GLKMatrix4Multiply(currentTransform, GLKMatrix4MakeTranslation(LERPTranslation.x, LERPTranslation.y, LERPTranslation.z)); currentTransform = GLKMatrix4Multiply(currentTransform, GLKMatrix4MakeScale(LERPScaling.x, LERPScaling.y, LERPScaling.z)); if (aSkeleton.joints[i].parentIndex == -1) { bindPosePalette[i] = aSkeleton.joints[i].inverseBindTransform; currentPosePalette[i] = currentTransform; } else { bindPosePalette[i] = GLKMatrix4Multiply(aSkeleton.joints[i].inverseBindTransform, bindPosePalette[aSkeleton.joints[i].parentIndex]); currentPosePalette[i] = GLKMatrix4Multiply(currentPosePalette[aSkeleton.joints[i].parentIndex], currentTransform); } aSkeleton.skinningPalette[i] = GLKMatrix4Multiply(currentPosePalette[i], bindPosePalette[i]); } } At this point, I should have my skinning palette. So on each frame in my vertex shader, I do: uniform mat4 modelMatrix; uniform mat4 projectionMatrix; uniform mat3 normalMatrix; uniform mat4 skinningPalette[6]; attribute vec4 position; attribute vec3 normal; attribute vec2 tCoordinates; attribute vec4 jointsWeights; attribute vec4 jointsIndices; varying highp vec2 tCoordinatesVarying; varying highp float lIntensity; void main() { vec3 eyeNormal = normalize(normalMatrix * normal); vec3 lightPosition = vec3(0., 0., 2.); lIntensity = max(0.0, dot(eyeNormal, normalize(lightPosition))); tCoordinatesVarying = tCoordinates; vec4 skinnedVertexPosition = vec4(0.); for (int i = 0; i < 4; i++) { skinnedVertexPosition += jointsWeights[i] * skinningPalette[int(jointsIndices[i])] * position; } gl_Position = projectionMatrix * modelMatrix * skinnedVertexPosition; } The result: The mesh parts that are supposed to animate do animate and follow the expected motion, however, the rotations are messed up in terms of orientations. That is, the mesh is not translated somewhere else or scaled in any way, but the orientations of rotations seem to be off. So a few observations: In the above shader notice I actually did not multiply the vertices by the mesh modelMatrix (the one which would take them to model or world or global space, whichever you prefer, since there is no parent to the mesh itself other than "the world") until after skinning. This is contrary to what I implied in the theory: if my skinning matrix takes vertices from model to joint and back to model space, I'd think the vertices should already be premultiplied by the mesh transform. But if I do so, I just get a black screen. As far as exporting the joints from Blender, my python script exports for each armature bone in bind pose, it's matrix in this way: def DFSJointTraversal(file, skeleton, jointList): for joint in jointList: poseJoint = skeleton.pose.bones[joint.name] jointTransform = poseJoint.matrix.inverted() file.write('Joint ' + joint.name + ' Transform {\n') for col in jointTransform.col: file.write('{:9f} {:9f} {:9f} {:9f}\n'.format(col[0], col[1], col[2], col[3])) DFSJointTraversal(file, skeleton, joint.children) file.write('}\n') And for current / keyframe poses (assuming I'm in the right keyframe): def exportAnimations(filepath): # Only one skeleton per scene objList = [object for object in bpy.context.scene.objects if object.type == 'ARMATURE'] if len(objList) == 0: return elif len(objList) > 1: return #raise exception? dialog box? skeleton = objList[0] jointNames = [bone.name for bone in skeleton.data.bones] for action in bpy.data.actions: # One animation clip per action in Blender, named as the action animationClipFilePath = filepath[0 : filepath.rindex('/') + 1] + action.name + ".aClip" file = open(animationClipFilePath, 'w') file.write('target skeleton: ' + skeleton.name + '\n') file.write('joints count: {:d}'.format(len(jointNames)) + '\n') skeleton.animation_data.action = action keyframeNum = max([len(fcurve.keyframe_points) for fcurve in action.fcurves]) keyframes = [] for fcurve in action.fcurves: for keyframe in fcurve.keyframe_points: keyframes.append(keyframe.co[0]) keyframes = set(keyframes) keyframes = [kf for kf in keyframes] keyframes.sort() file.write('keyframes count: {:d}'.format(len(keyframes)) + '\n') for kfIndex in keyframes: bpy.context.scene.frame_set(kfIndex) file.write('keyframe: {:d}\n'.format(int(kfIndex))) for i in range(0, len(skeleton.data.bones)): file.write('joint: {:d}\n'.format(i)) joint = skeleton.pose.bones[i] jointCurrentPoseTransform = joint.matrix translationV = jointCurrentPoseTransform.to_translation() rotationQ = jointCurrentPoseTransform.to_3x3().to_quaternion() scaleV = jointCurrentPoseTransform.to_scale() file.write('T {:9f} {:9f} {:9f}\n'.format(translationV[0], translationV[1], translationV[2])) file.write('Q {:9f} {:9f} {:9f} {:9f}\n'.format(rotationQ[1], rotationQ[2], rotationQ[3], rotationQ[0])) file.write('S {:9f} {:9f} {:9f}\n'.format(scaleV[0], scaleV[1], scaleV[2])) file.write('\n') file.close() Which I believe follow the theory explained at the beginning of my question. But then I checked out Blender's directX .x exporter for reference.. and what threw me off was that in the .x script they are exporting bind poses like so (transcribed using the same variable names I used so you can compare): if joint.parent: jointTransform = poseJoint.parent.matrix.inverted() else: jointTransform = Matrix() jointTransform *= poseJoint.matrix and exporting current keyframe poses like this: if joint.parent: jointCurrentPoseTransform = joint.parent.matrix.inverted() else: jointCurrentPoseTransform = Matrix() jointCurrentPoseTransform *= joint.matrix why are they using the parent's transform instead of the joint in question's? isn't the join transform assumed to exist in the context of a parent transform since after all it transforms from this joint's space to its parent's? Why are they concatenating in the same order for both bind poses and keyframe poses? If these two are then supposed to be concatenated with each other to cancel out the change of basis? Anyway, any ideas are appreciated.

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  • Display a Text Message During Bootup of Windows 7

    - by Mysticgeek
    Sometimes you might want to leave a text message for a user before they log into a Windows 7 computer. Today we show you a neat trick that allows you to leave a message they can read before logging in. Add a Text Message To add a message, click on Start and enter regedit into the Search box and hit Enter. Navigate to HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\Current Version\Policies\System and double-click on legalnoticecaption. In the Value data field enter in the header you want…for instance your company name or the name of your computer…whatever you want it to be, then click OK. Then double-click on legalnoticetext … And in the Value data field enter in the message you want to display and click OK. Close out of Registry Editor and reboot the computer.   After the machine reboots you’ll see the text message you just created at the Welcome screen.   You can include whatever text message you want to be included for the user to read before they log in. This is a neat trick if you have a company or school and want to show a particular message to the user before they log into the machine. Similar Articles Productive Geek Tips Start Your Computer More Quickly by Delaying the Startup of a Service in VistaCopy Windows Error Messages to the ClipboardHide the Recycle Bin Icon Text on Windows VistaHow To Disable Annoying Blinking Text in FirefoxStupid Geek Tricks: Using the Quick Zoom Feature in Outlook TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Combine MP3 Files Easily QuicklyCode Provides Cheatsheets & Other Programming Stuff Download Free MP3s from Amazon Awe inspiring, inter-galactic theme (Win 7) Case Study – How to Optimize Popular Wordpress Sites Restore Hidden Updates in Windows 7 & Vista

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  • DirectX9 / HLSL Shader Model 3 - Passing Doubles between Shaders

    - by P. Avery
    I need higher precision on a few values within my vertex and pixel shaders...I'm currently using floats, so I would like to use doubles...I've read that HLSL Model 4 has two functions to convert a double into two unsigned integers and back again( asuint() and asdouble() ). These functions are only supported on HLSL 4 and I am using DirectX 9 which will only compile HLSL Model 3 and below... How can I pass a double between shaders? here is implementation for HLSL 4: struct VS_INPUT { float2 v; }; struct PS_INPUT { uint a; uint b; uint c; uint d; }; PS_INPUT VertexShader( VS_INPUT Input ) { PS_INPUT Output = ( PS_INPUT )0; double2 vPos = mul( Input.v, mWorld ).xy; asuint( vPos.x, Output.a, Output.b ); asuint( vPos.y, Output.c, Output.d ); return Output; } float4 PixelShader( PS_INPUT Input ) { double2 vPos; vPos.x = asdouble( Input.a, Input.b ); vPos.y = asdouble( Input.c, Input.d ); ... return 1; }

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  • LINQ and conversion operators

    - by vik20000in
    LINQ has a habit of returning things as IEnumerable. But we have all been working with so many other format of lists like array ilist, dictionary etc that most of the time after having the result set we want to get them converted to one of our known format. For this reason LINQ has come up with helper method which can convert the result set in the desired format. Below is an example var sortedDoubles =         from d in doubles         orderby d descending         select d;     var doublesArray = sortedDoubles.ToArray(); This way we can also transfer the data to IList and Dictionary objects. Let’s say we have an array of Objects. The array contains all different types of data like double, int, null, string etc and we want only one type of data back then also we can use the helper function ofType. Below is an example     object[] numbers = { null, 1.0, "two", 3, "four", 5, "six", 7.0 };     var doubles = numbers.OfType<double>(); Vikram

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  • C#/.NET Little Wonders: The Predicate, Comparison, and Converter Generic Delegates

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. In the last three weeks, we examined the Action family of delegates (and delegates in general), the Func family of delegates, and the EventHandler family of delegates and how they can be used to support generic, reusable algorithms and classes. This week I will be completing my series on the generic delegates in the .NET Framework with a discussion of three more, somewhat less used, generic delegates: Predicate<T>, Comparison<T>, and Converter<TInput, TOutput>. These are older generic delegates that were introduced in .NET 2.0, mostly for use in the Array and List<T> classes.  Though older, it’s good to have an understanding of them and their intended purpose.  In addition, you can feel free to use them yourself, though obviously you can also use the equivalents from the Func family of delegates instead. Predicate<T> – delegate for determining matches The Predicate<T> delegate was a very early delegate developed in the .NET 2.0 Framework to determine if an item was a match for some condition in a List<T> or T[].  The methods that tend to use the Predicate<T> include: Find(), FindAll(), FindLast() Uses the Predicate<T> delegate to finds items, in a list/array of type T, that matches the given predicate. FindIndex(), FindLastIndex() Uses the Predicate<T> delegate to find the index of an item, of in a list/array of type T, that matches the given predicate. The signature of the Predicate<T> delegate (ignoring variance for the moment) is: 1: public delegate bool Predicate<T>(T obj); So, this is a delegate type that supports any method taking an item of type T and returning bool.  In addition, there is a semantic understanding that this predicate is supposed to be examining the item supplied to see if it matches a given criteria. 1: // finds first even number (2) 2: var firstEven = Array.Find(numbers, n => (n % 2) == 0); 3:  4: // finds all odd numbers (1, 3, 5, 7, 9) 5: var allEvens = Array.FindAll(numbers, n => (n % 2) == 1); 6:  7: // find index of first multiple of 5 (4) 8: var firstFiveMultiplePos = Array.FindIndex(numbers, n => (n % 5) == 0); This delegate has typically been succeeded in LINQ by the more general Func family, so that Predicate<T> and Func<T, bool> are logically identical.  Strictly speaking, though, they are different types, so a delegate reference of type Predicate<T> cannot be directly assigned to a delegate reference of type Func<T, bool>, though the same method can be assigned to both. 1: // SUCCESS: the same lambda can be assigned to either 2: Predicate<DateTime> isSameDayPred = dt => dt.Date == DateTime.Today; 3: Func<DateTime, bool> isSameDayFunc = dt => dt.Date == DateTime.Today; 4:  5: // ERROR: once they are assigned to a delegate type, they are strongly 6: // typed and cannot be directly assigned to other delegate types. 7: isSameDayPred = isSameDayFunc; When you assign a method to a delegate, all that is required is that the signature matches.  This is why the same method can be assigned to either delegate type since their signatures are the same.  However, once the method has been assigned to a delegate type, it is now a strongly-typed reference to that delegate type, and it cannot be assigned to a different delegate type (beyond the bounds of variance depending on Framework version, of course). Comparison<T> – delegate for determining order Just as the Predicate<T> generic delegate was birthed to give Array and List<T> the ability to perform type-safe matching, the Comparison<T> was birthed to give them the ability to perform type-safe ordering. The Comparison<T> is used in Array and List<T> for: Sort() A form of the Sort() method that takes a comparison delegate; this is an alternate way to custom sort a list/array from having to define custom IComparer<T> classes. The signature for the Comparison<T> delegate looks like (without variance): 1: public delegate int Comparison<T>(T lhs, T rhs); The goal of this delegate is to compare the left-hand-side to the right-hand-side and return a negative number if the lhs < rhs, zero if they are equal, and a positive number if the lhs > rhs.  Generally speaking, null is considered to be the smallest value of any reference type, so null should always be less than non-null, and two null values should be considered equal. In most sort/ordering methods, you must specify an IComparer<T> if you want to do custom sorting/ordering.  The Array and List<T> types, however, also allow for an alternative Comparison<T> delegate to be used instead, essentially, this lets you perform the custom sort without having to have the custom IComparer<T> class defined. It should be noted, however, that the LINQ OrderBy(), and ThenBy() family of methods do not support the Comparison<T> delegate (though one could easily add their own extension methods to create one, or create an IComparer() factory class that generates one from a Comparison<T>). So, given this delegate, we could use it to perform easy sorts on an Array or List<T> based on custom fields.  Say for example we have a data class called Employee with some basic employee information: 1: public sealed class Employee 2: { 3: public string Name { get; set; } 4: public int Id { get; set; } 5: public double Salary { get; set; } 6: } And say we had a List<Employee> that contained data, such as: 1: var employees = new List<Employee> 2: { 3: new Employee { Name = "John Smith", Id = 2, Salary = 37000.0 }, 4: new Employee { Name = "Jane Doe", Id = 1, Salary = 57000.0 }, 5: new Employee { Name = "John Doe", Id = 5, Salary = 60000.0 }, 6: new Employee { Name = "Jane Smith", Id = 3, Salary = 59000.0 } 7: }; Now, using the Comparison<T> delegate form of Sort() on the List<Employee>, we can sort our list many ways: 1: // sort based on employee ID 2: employees.Sort((lhs, rhs) => Comparer<int>.Default.Compare(lhs.Id, rhs.Id)); 3:  4: // sort based on employee name 5: employees.Sort((lhs, rhs) => string.Compare(lhs.Name, rhs.Name)); 6:  7: // sort based on salary, descending (note switched lhs/rhs order for descending) 8: employees.Sort((lhs, rhs) => Comparer<double>.Default.Compare(rhs.Salary, lhs.Salary)); So again, you could use this older delegate, which has a lot of logical meaning to it’s name, or use a generic delegate such as Func<T, T, int> to implement the same sort of behavior.  All this said, one of the reasons, in my opinion, that Comparison<T> isn’t used too often is that it tends to need complex lambdas, and the LINQ ability to order based on projections is much easier to use, though the Array and List<T> sorts tend to be more efficient if you want to perform in-place ordering. Converter<TInput, TOutput> – delegate to convert elements The Converter<TInput, TOutput> delegate is used by the Array and List<T> delegate to specify how to convert elements from an array/list of one type (TInput) to another type (TOutput).  It is used in an array/list for: ConvertAll() Converts all elements from a List<TInput> / TInput[] to a new List<TOutput> / TOutput[]. The delegate signature for Converter<TInput, TOutput> is very straightforward (ignoring variance): 1: public delegate TOutput Converter<TInput, TOutput>(TInput input); So, this delegate’s job is to taken an input item (of type TInput) and convert it to a return result (of type TOutput).  Again, this is logically equivalent to a newer Func delegate with a signature of Func<TInput, TOutput>.  In fact, the latter is how the LINQ conversion methods are defined. So, we could use the ConvertAll() syntax to convert a List<T> or T[] to different types, such as: 1: // get a list of just employee IDs 2: var empIds = employees.ConvertAll(emp => emp.Id); 3:  4: // get a list of all emp salaries, as int instead of double: 5: var empSalaries = employees.ConvertAll(emp => (int)emp.Salary); Note that the expressions above are logically equivalent to using LINQ’s Select() method, which gives you a lot more power: 1: // get a list of just employee IDs 2: var empIds = employees.Select(emp => emp.Id).ToList(); 3:  4: // get a list of all emp salaries, as int instead of double: 5: var empSalaries = employees.Select(emp => (int)emp.Salary).ToList(); The only difference with using LINQ is that many of the methods (including Select()) are deferred execution, which means that often times they will not perform the conversion for an item until it is requested.  This has both pros and cons in that you gain the benefit of not performing work until it is actually needed, but on the flip side if you want the results now, there is overhead in the behind-the-scenes work that support deferred execution (it’s supported by the yield return / yield break keywords in C# which define iterators that maintain current state information). In general, the new LINQ syntax is preferred, but the older Array and List<T> ConvertAll() methods are still around, as is the Converter<TInput, TOutput> delegate. Sidebar: Variance support update in .NET 4.0 Just like our descriptions of Func and Action, these three early generic delegates also support more variance in assignment as of .NET 4.0.  Their new signatures are: 1: // comparison is contravariant on type being compared 2: public delegate int Comparison<in T>(T lhs, T rhs); 3:  4: // converter is contravariant on input and covariant on output 5: public delegate TOutput Contravariant<in TInput, out TOutput>(TInput input); 6:  7: // predicate is contravariant on input 8: public delegate bool Predicate<in T>(T obj); Thus these delegates can now be assigned to delegates allowing for contravariance (going to a more derived type) or covariance (going to a less derived type) based on whether the parameters are input or output, respectively. Summary Today, we wrapped up our generic delegates discussion by looking at three lesser-used delegates: Predicate<T>, Comparison<T>, and Converter<TInput, TOutput>.  All three of these tend to be replaced by their more generic Func equivalents in LINQ, but that doesn’t mean you shouldn’t understand what they do or can’t use them for your own code, as they do contain semantic meanings in their names that sometimes get lost in the more generic Func name.   Tweet Technorati Tags: C#,CSharp,.NET,Little Wonders,delegates,generics,Predicate,Converter,Comparison

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  • how many times can i buy swtor credits with Extra 100% Bonus in Father’s Day at swtor2credits?

    - by user46860
    When you buy swtor credits, the most important factor must be the price of swtor credits! how can you get the cheap swtor credits? Big surprise for you: For such a special festival - Father’s Day, swtor2credits made a super promotion for all of the swtor players, in the only three days promotion time, you can buy 1600 credits with only $5.04, buy 2000 credits with only $6.30, and 3000k Credits just only need $9.44. The detail time is June 16 to June 18, 2014, 02:00-03:00 a.m. GMT! swtor2credits have been selling at a big loss with so much cheap swtor credits, this is mean 50% off for your order! that is really a crazy super promotion! So may you can not use the 8% disount code and getting double swtor credits at the same time! Everyone has only one chance to get double swtor credits at swtor2credits during our promotion.As long as your order has used extra discount code or voucher, you lose the chance to get exclusive 100% bonus. don't miss the time to buy such cheap swtor credits, like swtor2credits facebook give you more surprise, From May 29, 2014 to June 12.2014.GMT, you can gain Free Cash Coupon, Up to $16 Giveaways for Swtor Credits if you like swtor2credits facebook! http://www.swtor2credits.com/

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  • Calculating Screen Resolutions Using WPF

    - by Jeff Ferguson
    WPF measures all elements in device independent pixels (DIPs). These DIPs equate to device pixels if the current display monitor is set to the default of 96 DPI. However, for monitors set to a DPI setting that is different than 96 DPI, then WPF DIPs will not correspond directly to monitor pixels. Consider, for example, the WPF properties SystemParameters.PrimaryScreenHeight and SystemParameters.PrimaryScreenWidth. If your monitor resolution is set to 1024 pixels wide by 768 pixels high, and your monitor is set to 96 DPI, then WPF will report the value of SystemParameters.PrimaryScreenHeight as 768 and the value of SystemParameters.PrimaryScreenWidth as 1024. No problem. This aligns nicely because the WPF device independent pixel value (96) matches your monitor's DPI setting (96). However, if your monitor is not set to display pixels at 96 DPI, then SystemParameters.PrimaryScreenHeight and SystemParameters.PrimaryScreenWidth will not return what you expect. The values returned by these properties may be greater than or less than what you expect, depending on whether or not your monitor's DPI value is less than or greater than 96. Since the SystemParameters.PrimaryScreenHeight and SystemParameters.PrimaryScreenWidth properties are WPF properties, their values are measured in WPF DIPs, rather than taking monitor DPI into effect. Once again: WPF measures all elements in device independent pixels (DIPs). To combat this issue, you must take your monitor's DPI settings into effect if you're looking for the monitor's width and height using the monitor's DPI settings. The handy code block below will help you calculate these values regardless of the DPI setting on your monitor: Window MainWindow = Application.Current.MainWindow; PresentationSource MainWindowPresentationSource = PresentationSource.FromVisual(MainWindow); Matrix m = MainWindowPresentationSource.CompositionTarget.TransformToDevice; DpiWidthFactor = m.M11; DpiHeightFactor = m.M22; double ScreenHeight = SystemParameters.PrimaryScreenHeight * DpiHeightFactor; double ScreenWidth = SystemParameters.PrimaryScreenWidth * DpiWidthFactor; The values of ScreenHeight and ScreenWidth should, after this code is executed, match the resolution that you see in the display's Properties window.

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  • Dealing With Table Borders In OOXML

    - by Tim Murphy
    Note: Cross posted from Coding The Document. Permalink Formatting tables in a document programmatically can be a very complex task.  This is the major reason which we start our document generation projects with templates instead of building components in a document by hand. Borders are on aspect of a table that you may want to fomat.  Borders are used to make certain content in a table stand out.  If you need to conditionally set and remove borders there is something that you need to be aware of.  Even in OOXML you have the concepts of styles, inheriting styles and overriding styles. When Word defines a table it will reference a global style such as “TableGrid”.  This style will include the borders for the table.  Specifically the InsideHorizontalBorder and InsideVerticalBorder define the borders for the cells.  These can be overridden by the TableCellBorders collection of a particular cell.  Adding a double right border on a cell is as easy as the couple of lines of code below. wordprocessing.TableCellBorders borders = new wordprocessing.TableCellBorders(); borders.RightBorder = new RightBorder(){Val = BorderValues.Double, Color = "000000", ThemeColor = ThemeColorValues.Text1, Size = (UInt32Value)4U, Space = (UInt32Value)0U }; cell.TableCellProperties.Append(borders); If I want to revert back to the table’s style for cell borders I simply need to remove all children from the TableCellBorders collection.  It is like removing a class identifier from a TD tag in HTML.  The style in the parent object takes back over. With the knowledge of how the borders work you can take the concept and apply it to other effects of styles. del.icio.us Tags: OOXML,Office Open XML,Microsoft Office 2007,Microsoft Word 2007,table,style,border

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  • Steam freezes at login screen

    - by Snail284069
    I have just installed Steam on Xubuntu, and after it finished installing it went to the login screen, but the screen is frozen, and I cannot press the buttons. When running Steam though the terminal it says: alex@Craptop:~$ steam Running Steam on ubuntu 14.04 32-bit STEAM_RUNTIME is enabled automatically Installing breakpad exception handler for appid(steam)/version(1400690891_client) Installing breakpad exception handler for appid(steam)/version(1400690891_client) Installing breakpad exception handler for appid(steam)/version(1400690891_client) Installing breakpad exception handler for appid(steam)/version(1400690891_client) Gtk-Message: Failed to load module "overlay-scrollbar" Gtk-Message: Failed to load module "unity-gtk-module" Installing breakpad exception handler for appid(steam)/version(1400690891_client) [0522/174755:WARNING:proxy_service.cc(958)] PAC support disabled because there is no system implementation Fontconfig error: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 70: non-double matrix element Fontconfig error: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 70: non-double matrix element Fontconfig warning: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 78: saw unknown, expected number Installing breakpad exception handler for appid(steam)/version(1400690891_client) Installing breakpad exception handler for appid(steam)/version(1400690891_client) [HTTP Remote Control] HTTP server listening on port 35849. Installing breakpad exception handler for appid(steam)/version(1400690891_client) Installing breakpad exception handler for appid(steam)/version(1400690891_client) Process 2764 created /alex-ValveIPCSharedObjects5 Installing breakpad exception handler for appid(steam)/version(1400690891_client) Generating new string page texture 12: 48x256, total string texture memory is 49.15 KB Generating new string page texture 13: 256x256, total string texture memory is 311.30 KB Generating new string page texture 14: 128x256, total string texture memory is 442.37 KB Generating new string page texture 15: 384x256, total string texture memory is 835.58 KB and then the terminal gets stuck too, letting me type into it but not doing anything. I tried reinstalling and restarting the computer, but it still keeps happening.

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  • Types of quotes for an HTML templating language

    - by Ralph
    I'm developing a templating language, and now I'm trying to decide on what I should do with quotes. I'm thinking about having 3 different types of quotes which are all handled differently: backtick ` double quote " single quote ' expand variables ? yes no escape sequences no yes ? escape html no yes yes Backticks Backticks are meant to be used for outputting JavaScript or unescaped HTML. It's often handy to be able to pass variables into JS, but it could also cause issues with things being treated as variables that shouldn't. My variables are PHP-style ($var) so I'm thinking that might mess with jQuery pretty bad... but if I disable variable expansion w/ backticks then, I'm not sure how would insert a variable into a JS code block? Single Quotes Not sure if escape sequences like \n should be treated as literals or converted. I find it pretty rare that I want to disable escape sequences, but if you do, you could use backticks. So I'm leaning towards "yes" for this one, but that would be contrary to how PHP does it. Double Quotes Pretty certain I want everything enabled for this one. Modifiers I'm also thinking about adding modifiers like @ or r in front of the string that would change some of these options to enable a few more combinations. I would need 9 different quotes or 3 quotes and 2 modifiers to get every combination wouldn't I? My language also supports "filters" which can be applied against any "term" (number, variable, string) so you could always write something like "blah blah $var blah"|expandvars Or "my string"|escapehtml Thoughts? What would you prefer? What would be least confusing/most intuitive?

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  • New install of Steam not running on new install of Ubuntu 13.10

    - by inferKNOX
    I tried purging steam, un-installing and reinstalling steam, deleting /home/.steam/share/steam/appcache/, deleting everything in /home/.steam/share/steam/ and nothing helped. I installed Ubuntu, then steam into it directly afterward. I installed steam from Ubuntu Software Centre, launched it, it updated 206MB, then closed. When I tried to launch it again, it momentarily flashes the checking for update dialogue, then closes every time. Then (in an unrelated event) Ubuntu said some system updates are necessary and one of them was Steam launcher. I did the update, tried to launch Steam; same story. Really need help on this, as I did a complete re-isntall of Ubuntu, then Steam again and it did not help at all. Here's the log: user@computer:~$ steam Running Steam on ubuntu 13.10 64-bit STEAM_RUNTIME is enabled automatically Installing breakpad exception handler for appid(steam)/version(1381282832_client) Installing breakpad exception handler for appid(steam)/version(1381282832_client) Installing breakpad exception handler for appid(steam)/version(1381282832_client) unlinked 0 orphaned pipes removing stale semaphore last operated on by process 2297 with name 0eBlobRegistryMutex_313E4D748EE12691A95DDE8913185F7E removing stale semaphore last operated on by process 2297 with name 0eBlobRegistrySignal_313E4D748EE12691A95DDE8913185F7E removing stale semaphore last operated on by process 2297 with name 0emSteamEngineInstance removing stale semaphore last operated on by process 2297 with name 0eSteamEngineLock Gtk-Message: Failed to load module "overlay-scrollbar" Gtk-Message: Failed to load module "unity-gtk-module" Installing breakpad exception handler for appid(steam)/version(1381282832_client) Fontconfig error: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 70: non-double matrix element Fontconfig error: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 70: non-double matrix element Fontconfig warning: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 78: saw unknown, expected number [1030/115016:WARNING:proxy_service.cc(958)] PAC support disabled because there is no system implementation Installing breakpad exception handler for appid(steam)/version(1381282832_client) Installing breakpad exception handler for appid(steam)/version(1381282832_client) Installing breakpad exception handler for appid(steam)/version(1381282832_client) Installing breakpad exception handler for appid(steam)/version(1381282832_client) Steam: An X Error occurred X Error of failed request: BadValue (integer parameter out of range for operation) Major opcode of failed request: 18 (X_ChangeProperty) Value in failed request: 0x0 Serial number of failed request: 105 xerror_handler: X failed, continuing Uploading dump (out-of-process) [proxy ''] /tmp/dumps/crash_20131030115012_1.dmp /home/user/.local/share/Steam/steam.sh: line 717: 2650 Segmentation fault (core dumped) $STEAM_DEBUGGER "$STEAMROOT/$PLATFORM/$STEAMEXE" "$@" Finished uploading minidump (out-of-process): success = yes response: CrashID=bp-484ddae7-0b1c-4ae4-be84-42a9c2131030 Thanks in advance.

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  • Quick Script for Adding Skype Groups

    - by Robert May
    So, I needed to add about 30 people to several different Skype groups today, and I didn’t want to repeat the /add [skypename] thing over and over and over.  Building the list was a pain . . . I couldn’t find a good way to extract all of the users in an existing group.  There’s probably an api or something, but I just did that part by hand. Adding them to the groups was pretty easy with Windows Scripting Host.  Basically, I just ran this: <package>    <job id="vbs">       <script language="VBScript">          set WshShell = WScript.CreateObject("WScript.Shell")          WshShell.AppActivate 4484          WScript.Sleep 100          WshShell.SendKeys "/add user1~"          WScript.Sleep 100 …          WshShell.SendKeys "/add usern~"          WScript.Sleep 100       </script>    </job> </package> Add as many users as you need by copying the sendkeys and sleep lines.  Then, save the script to a .wsf file.  The AppActivate line needs to be changed to have the process id of skype instead of the number there.  To get that, open up Task Manager, click on Processes, then find skype.exe and find it’s PID. Before you double click on the file in windows explorer, you’ll need to have created the groups in skype.  For each group, open the group, and click in the chat window of the group.  Then double click on the WSF file.  If you don’t click in the chat window, you will likely get the add user dialog box instead of just adding the users. Technorati Tags: Skype,Script

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  • How can I cull non-visible isometric tiles?

    - by james
    I have a problem which I am struggling to solve. I have a large map of around 100x100 tiles which form an isometric map. The user is able to move the map around by dragging the mouse. I am trying to optimize my game only to draw the visible tiles. So far my code is like this. It appears to be ok in the x direction, but as soon as one tile goes completely above the top of the screen, the entire column disappears. I am not sure how to detect that all of the tiles in a particular column are outside the visible region. double maxTilesX = widthOfScreen/ halfTileWidth + 4; double maxTilesY = heightOfScreen/ halfTileHeight + 4; int rowStart = Math.max(0,( -xOffset / halfTileWidth)) ; int colStart = Math.max(0,( -yOffset / halfTileHeight)); rowEnd = (int) Math.min(mapSize, rowStart + maxTilesX); colEnd = (int) Math.min(mapSize, colStart + maxTilesY); EDIT - I think I have solved my problem, but perhaps not in a very efficient way. I have taken the center of the screen coordinates, determined which tile this corresponds to by converting the coordinates into cartesian format. I then update the entire box around the screen.

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  • Why does this game loop stop my process from responding?

    - by Ben
    I implemented a fixed time step loop for my C# game. All it does at the moment is make a square bounce around the screen. The problem I'm having is that when I execute the program, I can't close it from the window's close button and the cursor is stuck on the "busy" icon. I have to go into Visual Studio and stop the program manually. Here's the loop at the moment: public void run() { int updates = 0; int frames = 0; double msPerTick = 1000.0 / 60.0; double threshhold = 0; long lastTime = getCurrentTime(); long lastTimer = getCurrentTime(); while (true) { long currTime = getCurrentTime(); threshhold += (currTime - lastTime) / msPerTick; lastTime = currTime; while (threshhold >= 1) { update(); updates++; threshhold -= 1; } this.Refresh(); frames++; if ((getCurrentTime() - lastTimer) >= 1000) { this.Text = updates + " updates and " + frames + " frames per second"; updates = 0; frames = 0; lastTimer += 1000; } } } Why is this happening?

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  • Finding direction of travel in a world with wrapped edges

    - by crazy
    I need to find the shortest distance direction from one point in my 2D world to another point where the edges are wrapped (like asteroids etc). I know how to find the shortest distance but am struggling to find which direction it's in. The shortest distance is given by: int rows = MapY; int cols = MapX; int d1 = abs(S.Y - T.Y); int d2 = abs(S.X - T.X); int dr = min(d1, rows-d1); int dc = min(d2, cols-d2); double dist = sqrt((double)(dr*dr + dc*dc)); Example of the world : : T : :--------------:--------- : : : S : : : : : : T : : : :--------------: In the diagram the edges are shown with : and -. I've shown a wrapped repeat of the world at the top right too. I want to find the direction in degrees from S to T. So the shortest distance is to the top right repeat of T. but how do I calculate the direction in degreed from S to the repeated T in the top right? I know the positions of both S and T but I suppose I need to find the position of the repeated T however there more than 1. The worlds coordinates system starts at 0,0 at the top left and 0 degrees for the direction could start at West. It seems like this shouldn’t be too hard but I haven’t been able to work out a solution. I hope somone can help? Any websites would be appreciated.

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  • Can't get sprite to rotate correctly?

    - by rphello101
    I'm attempting to play with graphics using Java/Slick 2d. I'm trying to get my sprite to rotate to wherever the mouse is on the screen and then move accordingly. I figured the best way to do this was to keep track of the angle the sprite is at since I have to multiply the cosine/sine of the angle by the move speed in order to get the sprite to go "forwards" even if it is, say, facing 45 degrees in quadrant 3. However, before I even worry about that, I'm having trouble even getting my sprite to rotate in the first place. Preliminary console tests showed that this code worked, but when applied to the sprite, it just kind twitches. Anyone know what's wrong? int mX = Mouse.getX(); int mY = HEIGHT - Mouse.getY(); int pX = sprite.x; int pY = sprite.y; int tempY, tempX; double mAng, pAng = sprite.angle; double angRotate=0; if(mX!=pX){ tempY=pY-mY; tempX=mX-pX; mAng = Math.toDegrees(Math.atan2(Math.abs((tempY)),Math.abs((tempX)))); if(mAng==0 && mX<=pX) mAng=180; } else{ if(mY>pY) mAng=270; else mAng=90; } //Calculations if(mX<pX&&mY<pY){ //If in Q2 mAng = 180-mAng; } if(mX<pX&&mY>pY){ //If in Q3 mAng = 180+mAng; } if(mX>pX&&mY>pY){ //If in Q4 mAng = 360-mAng; } angRotate = mAng-pAng; sprite.angle = mAng; sprite.image.setRotation((float)angRotate);

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  • C# Cursor stuck on busy state

    - by Ben
    So I implemented a fixed time step loop for my C# game. All it does at the moment is make a square bounce around the screen. The problem I'm having is that when I execute the program, the window doesn't allow me to close the program and the cursor is stuck on the busy icon. I have to go into visual studio and stop the program manually. Here's the loop at the moment public void run() { int updates = 0; int frames = 0; double msPerTick = 1000.0 / 60.0; double threshhold = 0; long lastTime = getCurrentTime(); long lastTimer = getCurrentTime(); while (true) { long currTime = getCurrentTime(); threshhold += (currTime - lastTime) / msPerTick; lastTime = currTime; while (threshhold >= 1) { update(); updates++; threshhold -= 1; } this.Refresh(); frames++; if ((getCurrentTime() - lastTimer) >= 1000) { this.Text = updates + " updates and " + frames + " frames per second"; updates = 0; frames = 0; lastTimer += 1000; } } }

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  • Move a 2D square on y axis on android GLES2

    - by Dan
    I am trying to create a simple game for android, to start i am trying to make the square move down the y axis but the way i am doing it dosent move the square at all and i cant find any tutorials for GLES20 The on draw frame function in the render class updates the users position based on accleration dew to gravity, gets the transform matrix from the user class which is used to move the square down, then the program draws it. All that happens is that the square is drawn, no motion happens public void onDrawFrame(GL10 gl) { user.update(0.0, phy.AccelerationDewToGravity); GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_DEPTH_BUFFER_BIT); // Re draws black background GLES20.glVertexAttribPointer(maPositionHandle, 3, GLES20.GL_FLOAT, false, 12, user.SquareVB);//triangleVB); GLES20.glEnableVertexAttribArray(maPositionHandle); GLES20.glUniformMatrix4fv(maPositionHandle, 1, false, user.getTransformMatrix(), 0); GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4); } The update function in the player class is public void update(double vh, double vv) { Vh += vh; // Increase horrzontal Velosity Vv += vv; // Increase vertical velosity //Matrix.translateM(mMMatrix, 0, (int)Vh, (int)Vv, 0); Matrix.translateM(mMMatrix, 0, mMMatrix, 0, (float)Vh, (float)Vv, 0); }

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