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• Data persistance with BufferedReader and PrintWriter?

  - by Nazgulled

  I have this simple application with a couple of classes which are all related. There's one, the main one, for which there is only one instance of. I need to save save and load that using a text stream. My instructor requirement is BufferedReader to load the stream and PrintWriter to save it. But is this even possible? To persist a data object/class with a text stream? I know how to do it with and object, using serialization. But I don't see how am I supposed to do it using text streams. Suggestions?

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• How to Identify the website's content language

  - by Ajay

  I am developing a website to crawl the other website content in ASP.NET . I am able to get the content correctly but how can I identify which language is used based on that content. I used following code. HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(TextBox1.Text ); request.UserAgent = "A .NET Web Crawler"; WebResponse response = request.GetResponse(); Stream stream = response.GetResponseStream(); StreamReader reader = new StreamReader(stream); string htmlText = reader.ReadToEnd();

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• Serving large generated files using Google App Engine?

  - by John Carter

  Hiya, Presently I have a GAE app that does some offline processing (backs up a user's data), and generates a file that's somewhere in the neighbourhood of 10 - 100 MB. I'm not sure of the best way to serve this file to the user. The two options I'm considering are: Adding some code to the offline processing code that 'spoofs' it as a form upload to the blob store, and going thru the normal blobstore process to serve the file. Having the offline processing code store the file somewhere off of GAE, and serving it from there. Is there a much better approach I'm overlooking? I'm guessing this is functionality that isn't well suited to GAE. I had thought of storing in the datastore as db.Text or Dd.Blob but there I encounter the 1 MB limit. Any input would be appreciated,

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• Need help setting up json array

  - by torr

  A database query returns several rows which I loop through as follows: foreach ($query->result() as $row) { $data[$row->post_id]['post_id'] = $row->post_id; $data[$row->post_id]['post_type'] = $row->post_type; $data[$row->post_id]['post_text'] = $row->post_text; } If I json_encode the resulting array ($a['stream']) I get { "stream": { "1029": { "post_id": "1029", "post_type": "1", "post_text": "bla1", }, "1029": { "post_id": "1030", "post_type": "3", "post_text": "bla2", }, "1029": { "post_id": "1031", "post_type": "2", "post_text": "bla3", } } } But the json should actually look like this: { "stream": { "posts": [{ "post_id": "1029", "post_type": "1", "post_text": "bla1", }, { "post_id": "1030", "post_type": "3", "post_text": "bla2", }, { "post_id": "1031", "post_type": "2", "post_text": "bla3", }] } } How should I build my array to get this json right?

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• C# private (hidden) base class

  - by Loadmaster

  It is possible to make a C# base class accessible only within the library assembly it's compiled into, while making other subclasses that inherit from it public? For example: using System.IO; class BaseOutput: Stream // Hidden base class { protected BaseOutput(Stream o) { ... } ...lots of common methods... } public class MyOutput: BaseOutput // Public subclass { public BaseOutput(Stream o): base(o) { ... } public override int Write(int b) { ... } } Here I'd like the BaseOutput class to be inaccessible to clients of my library, but allow the subclass MyOutput to be completely public. I know that C# does not allow base classes to have more restrictive access than subclasses, but is there some other legal way of achieving the same effect?

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• What is the best strategy for a streaming screen capture application ?

  - by The_AlienCoder

  Ok Ive figured out how to do a screen capture of my desktop using Windows Media Encoder 9 + SDK and saving it as a movie on my hardrive. But now I want to take my project further and stream a realtime screen capture of my desktop . The idea is that users accessing my asp.net website will be able to view whatever Im doing on my desktop in real time via the video streaming from my computer. I really dont need the source code just the best strategy, procedure and server requirements.How will users access the streaming video on my website? Will it work on my godaddy shared hosting account or at what point will I need an upgrade? Will I be saving the stream to a file on the server for users to access or is there a way to stream directly ? I just need someone to point me in the right direction...

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• Content Types in browsers, can we use the Mime??

  - by SoLoGHoST

  Ok, I am wondering which mime types are dangerous in browsers? That is to say setting the Content Type to that mime type?? Which mime types, if any would pose a security risk?? I am noticing that many forum software, when uploading files, use the application/octet-stream for any files other than images and place that into the Content Type of the header. I am wondering why don't they place the actual mime-type instead into the Content Type? Are there security risks involved with this? So far I have used text/css, text/plain, audio/mpeg, and many others and haven't noticed any difference between application/octet-stream and these others. Does anyone out there know the exact difference, and what makes application/octet-stream any better, or any worse...to use for the Content Type?? Thank You :)

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• Struggling to "clear" a CGLayer -- can it even be done?

  - by Joe Blow

  So I'm doing this repetitively - making a CGLayer, doing some processing, and then releasing it. This happens a lot in real time -- so surely there is a lot of overhead in making a whole new CGLayer each time? Surely it would be better to just keep lair around, and start fresh each time? However, I do not know any way, at all, to "erase" or "start from blank" a CGLayer?? Can anyone help on this? There is a function CGContextBeginPath(cc) but it's confusing: it seems to only clear out "that" path, it does not erase all of the CGLayer back to a blank canvas. how to return a CGLayer to a blank canvas????? Does anyone know? CGLayerRef lair = CGLayerCreateWithContext( UIGraphicsGetCurrentContext(), CGSizeMake(1024,768), NULL); CGContextRef cc = CGLayerGetContext(ether); // various processing here CGContextAddPath(cc, somePath); // various processing here CGLayerRelease(lair); Any ideas?!

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• iPhone SDK SDL_openAudio with Multitasking Support

  - by brokedid

  Hello, I'm playing audio from a Online Live RTPS Stream with ffmpeg(because Apple doesn't support rtsp live streaming). Now I would play my Stream in the background. I started a thread in the background and registered the music for Background support. When the Application is entering in Background the NSThread is paused, and then Resuming after returning from background. If I start playing a Music (MP3-Stream) in the Application which use official Apple Frameworks then when the App is entering Background both Streams are played. What can I do to fix this?

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• Is there any memory restrictions on an ASP.Net application? HttpHandler?

  - by tpower

  I have an ASP.Net MVC application that allows users to upload images. When I try to upload a really large file (400MB) I get an error. I assumed that my image processing code (home brew) was very inefficient, so I decided I would try using a third party library to handle the image processing parts. Because I'm using TDD, I wanted to first write a test that fails. But when I test the controller action with the same large file it is able to do all the image processing without any trouble. The error I get is "Out of memory". I'm sure my code is probably using a lot more memory than it needs to but I just want to know why my test passes. The other difference is that I'm using SWFUpload which is not used with the test. Could this be the cause?

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• F# match char values

  - by rwallace

  I'm trying to match an integer expression against character literals, and the compiler complains about type mismatch. let rec read file includepath = let ch = ref 0 let token = ref 0 use stream = File.OpenText file let readch() = ch := stream.Read() let lex() = match !ch with | '!' -> readch() | _ -> token := !ch ch has to be an int because that's what stream.Read returns in order to use -1 as end of file marker. If I replace '!' with int '!' it still doesn't work. What's the best way to do this?

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• Android 3.2 HTTP streaming

  - by user1281053

  I'm trying to create an app to stream live TV. Currently the problem I'm facing is that after say 10 minutes of playing, the video will freeze but the audio will carry on. This is on a 1.3mbps stream. I also have lower streams, such as a 384kbps stream, that might last an hour or so, but will still do the same. I've tested this with a local video, that is high quality (file size is 2.3gb) and that has no lag and doesn't freeze at all, so it must be something to do with the way HLS is streamed to android. Does anyone have any idea on how to solve this problem? Thanks

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• How to split the definition of template friend funtion within template class?

  - by ~joke

  The following example compiles fine but I can't figure out how to separate declaration and definition of operator<<() is this particular case. Every time I try to split the definition friend is causing trouble and gcc complains the operator<<() definition must take exactly one argument. #include <iostream> template <typename T> class Test { public: Test(const T& value) : value_(value) {} template <typename STREAM> friend STREAM& operator<<(STREAM& os, const Test<T>& rhs) { os << rhs.value_; return os; } private: T value_; }; int main() { std::cout << Test<int>(5) << std::endl; }

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• Mvc4 webapi file download with jquery

  - by Ray

  I want to download file on client side from api apicontroller: public HttpResponseMessage PostOfficeSupplies() { string csv = string.Format ("D:\\Others\\Images/file.png"); HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.OK); result.Content = new StringContent(csv); result.Content.Headers.ContentType = new MediaTypeHeaderValue ("application/octet-stream"); result.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment"); result.Content.Headers.ContentDisposition.FileName = "file.png"; return result; } 1.How can I popup a download with jquery(octet-stream) from api controller? my client side code: $(document).ready(function () { $.ajax( { url: 'api/MyAPI' , type: "post" , contentType: "application/octet-stream" , data: '' , success: function (retData) { $("body").append("<iframe src='" + retData + "' style='display: none;' ></iframe>"); } }); }); but it was not work!!!Thanks!!

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• Using ftp in C# to send a file

  - by pm_2

  I'm trying to send a file using ftp. I have the following code: string server = "x.x.x.x"; // Just the IP Address FileStream stream = File.OpenRead(filename); byte[] buffer = new byte[stream.Length]; WebRequest request = WebRequest.Create("ftp://" + server); request.Method = WebRequestMethods.Ftp.UploadFile; request.Credentials = new NetworkCredential(username, password); Stream reqStream = request.GetRequestStream(); // This line fails reqStream.Write(buffer, 0, buffer.Length); reqStream.Close(); But when I run it, I get the following error: The requested URI is invalid for this FTP command. Please can anyone tell me why? Am I using this incorrectly?

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• Get XML from Server for Use on Windows Phone

  - by psheriff

  When working with mobile devices you always need to take into account bandwidth usage and power consumption. If you are constantly connecting to a server to retrieve data for an input screen, then you might think about moving some of that data down to the phone and cache the data on the phone. An example would be a static list of US State Codes that you are asking the user to select from. Since this is data that does not change very often, this is one set of data that would be great to cache on the phone. Since the Windows Phone does not have an embedded database, you can just use an XML string stored in Isolated Storage. Of course, then you need to figure out how to get data down to the phone. You can either ship it with the application, or connect and retrieve the data from your server one time and thereafter cache it and retrieve it from the cache. In this blog post you will see how to create a WCF service to retrieve data from a Product table in a database and send that data as XML to the phone and store it in Isolated Storage. You will then read that data from Isolated Storage using LINQ to XML and display it in a ListBox. Step 1: Create a Windows Phone Application The first step is to create a Windows Phone application called WP_GetXmlFromDataSet (or whatever you want to call it). On the MainPage.xaml add the following XAML within the “ContentPanel” grid: <StackPanel>  <Button Name="btnGetXml"          Content="Get XML"          Click="btnGetXml_Click" />  <Button Name="btnRead"          Content="Read XML"          IsEnabled="False"          Click="btnRead_Click" />  <ListBox Name="lstData"            Height="430"            ItemsSource="{Binding}"            DisplayMemberPath="ProductName" /></StackPanel> Now it is time to create the WCF Service Application that you will call to get the XML from a table in a SQL Server database. Step 2: Create a WCF Service Application Add a new project to your solution called WP_GetXmlFromDataSet.Services. Delete the IService1.* and Service1.* files and the App_Data folder, as you don’t generally need these items. Add a new WCF Service class called ProductService. In the IProductService class modify the void DoWork() method with the following code: [OperationContract]string GetProductXml(); Open the code behind in the ProductService.svc and create the GetProductXml() method. This method (shown below) will connect up to a database and retrieve data from a Product table. public string GetProductXml(){  string ret = string.Empty;  string sql = string.Empty;  SqlDataAdapter da;  DataSet ds = new DataSet();   sql = "SELECT ProductId, ProductName,";  sql += " IntroductionDate, Price";  sql += " FROM Product";   da = new SqlDataAdapter(sql,    ConfigurationManager.ConnectionStrings["Sandbox"].ConnectionString);   da.Fill(ds);   // Create Attribute based XML  foreach (DataColumn col in ds.Tables[0].Columns)  {    col.ColumnMapping = MappingType.Attribute;  }   ds.DataSetName = "Products";  ds.Tables[0].TableName = "Product";  ret = ds.GetXml();   return ret;} After retrieving the data from the Product table using a DataSet, you will want to set each column’s ColumnMapping property to Attribute. Using attribute based XML will make the data transferred across the wire a little smaller. You then set the DataSetName property to the top-level element name you want to assign to the XML. You then set the TableName property on the DataTable to the name you want each element to be in your XML. The last thing you need to do is to call the GetXml() method on the DataSet object which will return an XML string of the data in your DataSet object. This is the value that you will return from the service call. The XML that is returned from the above call looks like the following: <Products>  <Product ProductId="1"           ProductName="PDSA .NET Productivity Framework"           IntroductionDate="9/3/2010"           Price="5000" />  <Product ProductId="3"           ProductName="Haystack Code Generator for .NET"           IntroductionDate="7/1/2010"           Price="599.00" />  ...  ...  ... </Products> The GetProductXml() method uses a connection string from the Web.Config file, so add a <connectionStrings> element to the Web.Config file in your WCF Service application. Modify the settings shown below as needed for your server and database name. <connectionStrings>  <add name="Sandbox"        connectionString="Server=Localhost;Database=Sandbox;                         Integrated Security=Yes"/></connectionStrings> The Product Table You will need a Product table that you can read data from. I used the following structure for my product table. Add any data you want to this table after you create it in your database. CREATE TABLE Product(  ProductId int PRIMARY KEY IDENTITY(1,1) NOT NULL,  ProductName varchar(50) NOT NULL,  IntroductionDate datetime NULL,  Price money NULL) Step 3: Connect to WCF Service from Windows Phone Application Back in your Windows Phone application you will now need to add a Service Reference to the WCF Service application you just created. Right-mouse click on the Windows Phone Project and choose Add Service Reference… from the context menu. Click on the Discover button. In the Namespace text box enter “ProductServiceRefrence”, then click the OK button. If you entered everything correctly, Visual Studio will generate some code that allows you to connect to your Product service. On the MainPage.xaml designer window double click on the Get XML button to generate the Click event procedure for this button. In the Click event procedure make a call to a GetXmlFromServer() method. This method will also need a “Completed” event procedure to be written since all communication with a WCF Service from Windows Phone must be asynchronous.  Write these two methods as follows: private const string KEY_NAME = "ProductData"; private void GetXmlFromServer(){  ProductServiceClient client = new ProductServiceClient();   client.GetProductXmlCompleted += new     EventHandler<GetProductXmlCompletedEventArgs>      (client_GetProductXmlCompleted);   client.GetProductXmlAsync();  client.CloseAsync();} void client_GetProductXmlCompleted(object sender,                                   GetProductXmlCompletedEventArgs e){  // Store XML data in Isolated Storage  IsolatedStorageSettings.ApplicationSettings[KEY_NAME] = e.Result;   btnRead.IsEnabled = true;} As you can see, this is a fairly standard call to a WCF Service. In the Completed event you get the Result from the event argument, which is the XML, and store it into Isolated Storage using the IsolatedStorageSettings.ApplicationSettings class. Notice the constant that I added to specify the name of the key. You will use this constant later to read the data from Isolated Storage. Step 4: Create a Product Class Even though you stored XML data into Isolated Storage when you read that data out you will want to convert each element in the XML file into an actual Product object. This means that you need to create a Product class in your Windows Phone application. Add a Product class to your project that looks like the code below: public class Product{  public string ProductName{ get; set; }  public int ProductId{ get; set; }  public DateTime IntroductionDate{ get; set; }  public decimal Price{ get; set; }} Step 5: Read Settings from Isolated Storage Now that you have the XML data stored in Isolated Storage, it is time to use it. Go back to the MainPage.xaml design view and double click on the Read XML button to generate the Click event procedure. From the Click event procedure call a method named ReadProductXml().Create this method as shown below: private void ReadProductXml(){  XElement xElem = null;   if (IsolatedStorageSettings.ApplicationSettings.Contains(KEY_NAME))  {    xElem = XElement.Parse(     IsolatedStorageSettings.ApplicationSettings[KEY_NAME].ToString());     // Create a list of Product objects    var products =         from prod in xElem.Descendants("Product")        orderby prod.Attribute("ProductName").Value        select new Product        {          ProductId = Convert.ToInt32(prod.Attribute("ProductId").Value),          ProductName = prod.Attribute("ProductName").Value,          IntroductionDate =             Convert.ToDateTime(prod.Attribute("IntroductionDate").Value),          Price = Convert.ToDecimal(prod.Attribute("Price").Value)        };     lstData.DataContext = products;  }} The ReadProductXml() method checks to make sure that the key name that you saved your XML as exists in Isolated Storage prior to trying to open it. If the key name exists, then you retrieve the value as a string. Use the XElement’s Parse method to convert the XML string to a XElement object. LINQ to XML is used to iterate over each element in the XElement object and create a new Product object from each attribute in your XML file. The LINQ to XML code also orders the XML data by the ProductName. After the LINQ to XML code runs you end up with an IEnumerable collection of Product objects in the variable named “products”. You assign this collection of product data to the DataContext of the ListBox you created in XAML. The DisplayMemberPath property of the ListBox is set to “ProductName” so it will now display the product name for each row in your products collection. Summary In this article you learned how to retrieve an XML string from a table in a database, return that string across a WCF Service and store it into Isolated Storage on your Windows Phone. You then used LINQ to XML to create a collection of Product objects from the data stored and display that data in a Windows Phone list box. This same technique can be used in Silverlight or WPF applications too. NOTE: You can download the complete sample code at my website. http://www.pdsa.com/downloads. Choose Tips & Tricks, then "Get XML From Server for Use on Windows Phone" 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 video on Silverlight entitled Silverlight XAML for the Complete Novice - Part 1.  

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• Camera doesnt move on opengl qt

  - by hugo

  Here is my code, as my subject indicates i have implemented a camera but i couldnt make it move,Thanks in advance. #define PI_OVER_180 0.0174532925f define GL_CLAMP_TO_EDGE 0x812F include "metinalifeyyaz.h" include include include include include include include metinalifeyyaz::metinalifeyyaz(QWidget *parent) : QGLWidget(parent) { this->setFocusPolicy(Qt:: StrongFocus); time = QTime::currentTime(); timer = new QTimer(this); timer->setSingleShot(true); connect(timer, SIGNAL(timeout()), this, SLOT(updateGL())); xpos = yrot = zpos = 0; walkbias = walkbiasangle = lookupdown = 0.0f; keyUp = keyDown = keyLeft = keyRight = keyPageUp = keyPageDown = false; } void metinalifeyyaz::drawBall() { //glTranslatef(6,0,4); glutSolidSphere(0.10005,300,30); } metinalifeyyaz:: ~metinalifeyyaz(){ glDeleteTextures(1,texture); } void metinalifeyyaz::initializeGL(){ glShadeModel(GL_SMOOTH); glClearColor(1.0,1.0,1.0,0.5); glClearDepth(1.0f); glEnable(GL_DEPTH_TEST); glEnable(GL_TEXTURE_2D); glDepthFunc(GL_LEQUAL); glClearColor(1.0,1.0,1.0,1.0); glShadeModel(GL_SMOOTH); GLfloat mat_specular[]={1.0,1.0,1.0,1.0}; GLfloat mat_shininess []={30.0}; GLfloat light_position[]={1.0,1.0,1.0}; glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular); glMaterialfv(GL_FRONT,GL_SHININESS,mat_shininess); glLightfv(GL_LIGHT0, GL_POSITION, light_position); glEnable(GL_LIGHT0); glEnable(GL_LIGHTING); QImage img1 = convertToGLFormat(QImage(":/new/prefix1/halisaha2.bmp")); QImage img2 = convertToGLFormat(QImage(":/new/prefix1/white.bmp")); glGenTextures(2,texture); glBindTexture(GL_TEXTURE_2D, texture[0]); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, img1.width(), img1.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, img1.bits()); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glBindTexture(GL_TEXTURE_2D, texture[1]); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, img2.width(), img2.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, img2.bits()); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); // Really nice perspective calculations } void metinalifeyyaz::resizeGL(int w, int h){ if(h==0) h=1; glViewport(0,0,w,h); glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(45.0f, static_cast<GLfloat>(w)/h,0.1f,100.0f); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); } void metinalifeyyaz::paintGL(){ movePlayer(); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glLoadIdentity(); GLfloat xtrans = -xpos; GLfloat ytrans = -walkbias - 0.50f; GLfloat ztrans = -zpos; GLfloat sceneroty = 360.0f - yrot; glLoadIdentity(); glRotatef(lookupdown, 1.0f, 0.0f, 0.0f); glRotatef(sceneroty, 0.0f, 1.0f, 0.0f); glTranslatef(xtrans, ytrans+50, ztrans-130); glLoadIdentity(); glTranslatef(1.0f,0.0f,-18.0f); glRotatef(45,1,0,0); drawScene(); int delay = time.msecsTo(QTime::currentTime()); if (delay == 0) delay = 1; time = QTime::currentTime(); timer->start(qMax(0,10 - delay)); } void metinalifeyyaz::movePlayer() { if (keyUp) { xpos -= sin(yrot * PI_OVER_180) * 0.5f; zpos -= cos(yrot * PI_OVER_180) * 0.5f; if (walkbiasangle >= 360.0f) walkbiasangle = 0.0f; else walkbiasangle += 7.0f; walkbias = sin(walkbiasangle * PI_OVER_180) / 10.0f; } else if (keyDown) { xpos += sin(yrot * PI_OVER_180)*0.5f; zpos += cos(yrot * PI_OVER_180)*0.5f ; if (walkbiasangle <= 7.0f) walkbiasangle = 360.0f; else walkbiasangle -= 7.0f; walkbias = sin(walkbiasangle * PI_OVER_180) / 10.0f; } if (keyLeft) yrot += 0.5f; else if (keyRight) yrot -= 0.5f; if (keyPageUp) lookupdown -= 0.5; else if (keyPageDown) lookupdown += 0.5; } void metinalifeyyaz::keyPressEvent(QKeyEvent *event) { switch (event->key()) { case Qt::Key_Escape: close(); break; case Qt::Key_F1: setWindowState(windowState() ^ Qt::WindowFullScreen); break; default: QGLWidget::keyPressEvent(event); case Qt::Key_PageUp: keyPageUp = true; break; case Qt::Key_PageDown: keyPageDown = true; break; case Qt::Key_Left: keyLeft = true; break; case Qt::Key_Right: keyRight = true; break; case Qt::Key_Up: keyUp = true; break; case Qt::Key_Down: keyDown = true; break; } } void metinalifeyyaz::changeEvent(QEvent *event) { switch (event->type()) { case QEvent::WindowStateChange: if (windowState() == Qt::WindowFullScreen) setCursor(Qt::BlankCursor); else unsetCursor(); break; default: break; } } void metinalifeyyaz::keyReleaseEvent(QKeyEvent *event) { switch (event->key()) { case Qt::Key_PageUp: keyPageUp = false; break; case Qt::Key_PageDown: keyPageDown = false; break; case Qt::Key_Left: keyLeft = false; break; case Qt::Key_Right: keyRight = false; break; case Qt::Key_Up: keyUp = false; break; case Qt::Key_Down: keyDown = false; break; default: QGLWidget::keyReleaseEvent(event); } } void metinalifeyyaz::drawScene(){ glBegin(GL_QUADS); glNormal3f(0.0f,0.0f,1.0f); // glColor3f(0,0,1); //back glVertex3f(-6,0,-4); glVertex3f(-6,-0.5,-4); glVertex3f(6,-0.5,-4); glVertex3f(6,0,-4); glEnd(); glBegin(GL_QUADS); glNormal3f(0.0f,0.0f,-1.0f); //front glVertex3f(6,0,4); glVertex3f(6,-0.5,4); glVertex3f(-6,-0.5,4); glVertex3f(-6,0,4); glEnd(); glBegin(GL_QUADS); glNormal3f(-1.0f,0.0f,0.0f); // glColor3f(0,0,1); //left glVertex3f(-6,0,4); glVertex3f(-6,-0.5,4); glVertex3f(-6,-0.5,-4); glVertex3f(-6,0,-4); glEnd(); glBegin(GL_QUADS); glNormal3f(1.0f,0.0f,0.0f); // glColor3f(0,0,1); //right glVertex3f(6,0,-4); glVertex3f(6,-0.5,-4); glVertex3f(6,-0.5,4); glVertex3f(6,0,4); glEnd(); glBindTexture(GL_TEXTURE_2D, texture[0]); glBegin(GL_QUADS); glNormal3f(0.0f,1.0f,0.0f);//top glTexCoord2f(1.0f,0.0f); glVertex3f(6,0,-4); glTexCoord2f(1.0f,1.0f); glVertex3f(6,0,4); glTexCoord2f(0.0f,1.0f); glVertex3f(-6,0,4); glTexCoord2f(0.0f,0.0f); glVertex3f(-6,0,-4); glEnd(); glBegin(GL_QUADS); glNormal3f(0.0f,-1.0f,0.0f); //glColor3f(0,0,1); //bottom glVertex3f(6,-0.5,-4); glVertex3f(6,-0.5,4); glVertex3f(-6,-0.5,4); glVertex3f(-6,-0.5,-4); glEnd(); // glPushMatrix(); glBindTexture(GL_TEXTURE_2D, texture[1]); glBegin(GL_QUADS); glNormal3f(1.0f,0.0f,0.0f); glTexCoord2f(1.0f,0.0f); //right far goal post front face glVertex3f(5,0.5,-0.95); glTexCoord2f(1.0f,1.0f); glVertex3f(5,0,-0.95); glTexCoord2f(0.0f,1.0f); glVertex3f(5,0,-1); glTexCoord2f(0.0f,0.0f); glVertex3f(5, 0.5, -1); glColor3f(1,1,1); //right far goal post back face glVertex3f(5.05,0.5,-0.95); glVertex3f(5.05,0,-0.95); glVertex3f(5.05,0,-1); glVertex3f(5.05, 0.5, -1); glColor3f(1,1,1); //right far goal post left face glVertex3f(5,0.5,-1); glVertex3f(5,0,-1); glVertex3f(5.05,0,-1); glVertex3f(5.05, 0.5, -1); glColor3f(1,1,1); //right far goal post right face glVertex3f(5.05,0.5,-0.95); glVertex3f(5.05,0,-0.95); glVertex3f(5,0,-0.95); glVertex3f(5, 0.5, -0.95); glColor3f(1,1,1); //right near goal post front face glVertex3f(5,0.5,0.95); glVertex3f(5,0,0.95); glVertex3f(5,0,1); glVertex3f(5,0.5, 1); glColor3f(1,1,1); //right near goal post back face glVertex3f(5.05,0.5,0.95); glVertex3f(5.05,0,0.95); glVertex3f(5.05,0,1); glVertex3f(5.05,0.5, 1); glColor3f(1,1,1); //right near goal post left face glVertex3f(5,0.5,1); glVertex3f(5,0,1); glVertex3f(5.05,0,1); glVertex3f(5.05,0.5, 1); glColor3f(1,1,1); //right near goal post right face glVertex3f(5.05,0.5,0.95); glVertex3f(5.05,0,0.95); glVertex3f(5,0,0.95); glVertex3f(5,0.5, 0.95); glColor3f(1,1,1); //right crossbar front face glVertex3f(5,0.55,-1); glVertex3f(5,0.55,1); glVertex3f(5,0.5,1); glVertex3f(5,0.5,-1); glColor3f(1,1,1); //right crossbar back face glVertex3f(5.05,0.55,-1); glVertex3f(5.05,0.55,1); glVertex3f(5.05,0.5,1); glVertex3f(5.05,0.5,-1); glColor3f(1,1,1); //right crossbar bottom face glVertex3f(5.05,0.5,-1); glVertex3f(5.05,0.5,1); glVertex3f(5,0.5,1); glVertex3f(5,0.5,-1); glColor3f(1,1,1); //right crossbar top face glVertex3f(5.05,0.55,-1); glVertex3f(5.05,0.55,1); glVertex3f(5,0.55,1); glVertex3f(5,0.55,-1); glColor3f(1,1,1); //left far goal post front face glVertex3f(-5,0.5,-0.95); glVertex3f(-5,0,-0.95); glVertex3f(-5,0,-1); glVertex3f(-5, 0.5, -1); glColor3f(1,1,1); //right far goal post back face glVertex3f(-5.05,0.5,-0.95); glVertex3f(-5.05,0,-0.95); glVertex3f(-5.05,0,-1); glVertex3f(-5.05, 0.5, -1); glColor3f(1,1,1); //right far goal post left face glVertex3f(-5,0.5,-1); glVertex3f(-5,0,-1); glVertex3f(-5.05,0,-1); glVertex3f(-5.05, 0.5, -1); glColor3f(1,1,1); //right far goal post right face glVertex3f(-5.05,0.5,-0.95); glVertex3f(-5.05,0,-0.95); glVertex3f(-5,0,-0.95); glVertex3f(-5, 0.5, -0.95); glColor3f(1,1,1); //left near goal post front face glVertex3f(-5,0.5,0.95); glVertex3f(-5,0,0.95); glVertex3f(-5,0,1); glVertex3f(-5,0.5, 1); glColor3f(1,1,1); //right near goal post back face glVertex3f(-5.05,0.5,0.95); glVertex3f(-5.05,0,0.95); glVertex3f(-5.05,0,1); glVertex3f(-5.05,0.5, 1); glColor3f(1,1,1); //right near goal post left face glVertex3f(-5,0.5,1); glVertex3f(-5,0,1); glVertex3f(-5.05,0,1); glVertex3f(-5.05,0.5, 1); glColor3f(1,1,1); //right near goal post right face glVertex3f(-5.05,0.5,0.95); glVertex3f(-5.05,0,0.95); glVertex3f(-5,0,0.95); glVertex3f(-5,0.5, 0.95); glColor3f(1,1,1); //left crossbar front face glVertex3f(-5,0.55,-1); glVertex3f(-5,0.55,1); glVertex3f(-5,0.5,1); glVertex3f(-5,0.5,-1); glColor3f(1,1,1); //right crossbar back face glVertex3f(-5.05,0.55,-1); glVertex3f(-5.05,0.55,1); glVertex3f(-5.05,0.5,1); glVertex3f(-5.05,0.5,-1); glColor3f(1,1,1); //right crossbar bottom face glVertex3f(-5.05,0.5,-1); glVertex3f(-5.05,0.5,1); glVertex3f(-5,0.5,1); glVertex3f(-5,0.5,-1); glColor3f(1,1,1); //right crossbar top face glVertex3f(-5.05,0.55,-1); glVertex3f(-5.05,0.55,1); glVertex3f(-5,0.55,1); glVertex3f(-5,0.55,-1); glEnd(); // glPopMatrix(); // glPushMatrix(); // glTranslatef(0,0,0); // glutSolidSphere(0.10005,500,30); // glPopMatrix(); }

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• Camera doesn't move

  - by hugo

  Here is my code, as my subject indicates i have implemented a camera but I couldn't make it move. #define PI_OVER_180 0.0174532925f #define GL_CLAMP_TO_EDGE 0x812F #include "metinalifeyyaz.h" #include <GL/glu.h> #include <GL/glut.h> #include <QTimer> #include <cmath> #include <QKeyEvent> #include <QWidget> #include <QDebug> metinalifeyyaz::metinalifeyyaz(QWidget *parent) : QGLWidget(parent) { this->setFocusPolicy(Qt:: StrongFocus); time = QTime::currentTime(); timer = new QTimer(this); timer->setSingleShot(true); connect(timer, SIGNAL(timeout()), this, SLOT(updateGL())); xpos = yrot = zpos = 0; walkbias = walkbiasangle = lookupdown = 0.0f; keyUp = keyDown = keyLeft = keyRight = keyPageUp = keyPageDown = false; } void metinalifeyyaz::drawBall() { //glTranslatef(6,0,4); glutSolidSphere(0.10005,300,30); } metinalifeyyaz:: ~metinalifeyyaz(){ glDeleteTextures(1,texture); } void metinalifeyyaz::initializeGL(){ glShadeModel(GL_SMOOTH); glClearColor(1.0,1.0,1.0,0.5); glClearDepth(1.0f); glEnable(GL_DEPTH_TEST); glEnable(GL_TEXTURE_2D); glDepthFunc(GL_LEQUAL); glClearColor(1.0,1.0,1.0,1.0); glShadeModel(GL_SMOOTH); GLfloat mat_specular[]={1.0,1.0,1.0,1.0}; GLfloat mat_shininess []={30.0}; GLfloat light_position[]={1.0,1.0,1.0}; glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular); glMaterialfv(GL_FRONT,GL_SHININESS,mat_shininess); glLightfv(GL_LIGHT0, GL_POSITION, light_position); glEnable(GL_LIGHT0); glEnable(GL_LIGHTING); QImage img1 = convertToGLFormat(QImage(":/new/prefix1/halisaha2.bmp")); QImage img2 = convertToGLFormat(QImage(":/new/prefix1/white.bmp")); glGenTextures(2,texture); glBindTexture(GL_TEXTURE_2D, texture[0]); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, img1.width(), img1.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, img1.bits()); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glBindTexture(GL_TEXTURE_2D, texture[1]); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, img2.width(), img2.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, img2.bits()); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); // Really nice perspective calculations } void metinalifeyyaz::resizeGL(int w, int h){ if(h==0) h=1; glViewport(0,0,w,h); glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(45.0f, static_cast<GLfloat>(w)/h,0.1f,100.0f); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); } void metinalifeyyaz::paintGL(){ movePlayer(); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glLoadIdentity(); GLfloat xtrans = -xpos; GLfloat ytrans = -walkbias - 0.50f; GLfloat ztrans = -zpos; GLfloat sceneroty = 360.0f - yrot; glLoadIdentity(); glRotatef(lookupdown, 1.0f, 0.0f, 0.0f); glRotatef(sceneroty, 0.0f, 1.0f, 0.0f); glTranslatef(xtrans, ytrans+50, ztrans-130); glLoadIdentity(); glTranslatef(1.0f,0.0f,-18.0f); glRotatef(45,1,0,0); drawScene(); int delay = time.msecsTo(QTime::currentTime()); if (delay == 0) delay = 1; time = QTime::currentTime(); timer->start(qMax(0,10 - delay)); } void metinalifeyyaz::movePlayer() { if (keyUp) { xpos -= sin(yrot * PI_OVER_180) * 0.5f; zpos -= cos(yrot * PI_OVER_180) * 0.5f; if (walkbiasangle >= 360.0f) walkbiasangle = 0.0f; else walkbiasangle += 7.0f; walkbias = sin(walkbiasangle * PI_OVER_180) / 10.0f; } else if (keyDown) { xpos += sin(yrot * PI_OVER_180)*0.5f; zpos += cos(yrot * PI_OVER_180)*0.5f ; if (walkbiasangle <= 7.0f) walkbiasangle = 360.0f; else walkbiasangle -= 7.0f; walkbias = sin(walkbiasangle * PI_OVER_180) / 10.0f; } if (keyLeft) yrot += 0.5f; else if (keyRight) yrot -= 0.5f; if (keyPageUp) lookupdown -= 0.5; else if (keyPageDown) lookupdown += 0.5; } void metinalifeyyaz::keyPressEvent(QKeyEvent *event) { switch (event->key()) { case Qt::Key_Escape: close(); break; case Qt::Key_F1: setWindowState(windowState() ^ Qt::WindowFullScreen); break; default: QGLWidget::keyPressEvent(event); case Qt::Key_PageUp: keyPageUp = true; break; case Qt::Key_PageDown: keyPageDown = true; break; case Qt::Key_Left: keyLeft = true; break; case Qt::Key_Right: keyRight = true; break; case Qt::Key_Up: keyUp = true; break; case Qt::Key_Down: keyDown = true; break; } } void metinalifeyyaz::changeEvent(QEvent *event) { switch (event->type()) { case QEvent::WindowStateChange: if (windowState() == Qt::WindowFullScreen) setCursor(Qt::BlankCursor); else unsetCursor(); break; default: break; } } void metinalifeyyaz::keyReleaseEvent(QKeyEvent *event) { switch (event->key()) { case Qt::Key_PageUp: keyPageUp = false; break; case Qt::Key_PageDown: keyPageDown = false; break; case Qt::Key_Left: keyLeft = false; break; case Qt::Key_Right: keyRight = false; break; case Qt::Key_Up: keyUp = false; break; case Qt::Key_Down: keyDown = false; break; default: QGLWidget::keyReleaseEvent(event); } } void metinalifeyyaz::drawScene(){ glBegin(GL_QUADS); glNormal3f(0.0f,0.0f,1.0f); // glColor3f(0,0,1); //back glVertex3f(-6,0,-4); glVertex3f(-6,-0.5,-4); glVertex3f(6,-0.5,-4); glVertex3f(6,0,-4); glEnd(); glBegin(GL_QUADS); glNormal3f(0.0f,0.0f,-1.0f); //front glVertex3f(6,0,4); glVertex3f(6,-0.5,4); glVertex3f(-6,-0.5,4); glVertex3f(-6,0,4); glEnd(); glBegin(GL_QUADS); glNormal3f(-1.0f,0.0f,0.0f); // glColor3f(0,0,1); //left glVertex3f(-6,0,4); glVertex3f(-6,-0.5,4); glVertex3f(-6,-0.5,-4); glVertex3f(-6,0,-4); glEnd(); glBegin(GL_QUADS); glNormal3f(1.0f,0.0f,0.0f); // glColor3f(0,0,1); //right glVertex3f(6,0,-4); glVertex3f(6,-0.5,-4); glVertex3f(6,-0.5,4); glVertex3f(6,0,4); glEnd(); glBindTexture(GL_TEXTURE_2D, texture[0]); glBegin(GL_QUADS); glNormal3f(0.0f,1.0f,0.0f);//top glTexCoord2f(1.0f,0.0f); glVertex3f(6,0,-4); glTexCoord2f(1.0f,1.0f); glVertex3f(6,0,4); glTexCoord2f(0.0f,1.0f); glVertex3f(-6,0,4); glTexCoord2f(0.0f,0.0f); glVertex3f(-6,0,-4); glEnd(); glBegin(GL_QUADS); glNormal3f(0.0f,-1.0f,0.0f); //glColor3f(0,0,1); //bottom glVertex3f(6,-0.5,-4); glVertex3f(6,-0.5,4); glVertex3f(-6,-0.5,4); glVertex3f(-6,-0.5,-4); glEnd(); // glPushMatrix(); glBindTexture(GL_TEXTURE_2D, texture[1]); glBegin(GL_QUADS); glNormal3f(1.0f,0.0f,0.0f); glTexCoord2f(1.0f,0.0f); //right far goal post front face glVertex3f(5,0.5,-0.95); glTexCoord2f(1.0f,1.0f); glVertex3f(5,0,-0.95); glTexCoord2f(0.0f,1.0f); glVertex3f(5,0,-1); glTexCoord2f(0.0f,0.0f); glVertex3f(5, 0.5, -1); glColor3f(1,1,1); //right far goal post back face glVertex3f(5.05,0.5,-0.95); glVertex3f(5.05,0,-0.95); glVertex3f(5.05,0,-1); glVertex3f(5.05, 0.5, -1); glColor3f(1,1,1); //right far goal post left face glVertex3f(5,0.5,-1); glVertex3f(5,0,-1); glVertex3f(5.05,0,-1); glVertex3f(5.05, 0.5, -1); glColor3f(1,1,1); //right far goal post right face glVertex3f(5.05,0.5,-0.95); glVertex3f(5.05,0,-0.95); glVertex3f(5,0,-0.95); glVertex3f(5, 0.5, -0.95); glColor3f(1,1,1); //right near goal post front face glVertex3f(5,0.5,0.95); glVertex3f(5,0,0.95); glVertex3f(5,0,1); glVertex3f(5,0.5, 1); glColor3f(1,1,1); //right near goal post back face glVertex3f(5.05,0.5,0.95); glVertex3f(5.05,0,0.95); glVertex3f(5.05,0,1); glVertex3f(5.05,0.5, 1); glColor3f(1,1,1); //right near goal post left face glVertex3f(5,0.5,1); glVertex3f(5,0,1); glVertex3f(5.05,0,1); glVertex3f(5.05,0.5, 1); glColor3f(1,1,1); //right near goal post right face glVertex3f(5.05,0.5,0.95); glVertex3f(5.05,0,0.95); glVertex3f(5,0,0.95); glVertex3f(5,0.5, 0.95); glColor3f(1,1,1); //right crossbar front face glVertex3f(5,0.55,-1); glVertex3f(5,0.55,1); glVertex3f(5,0.5,1); glVertex3f(5,0.5,-1); glColor3f(1,1,1); //right crossbar back face glVertex3f(5.05,0.55,-1); glVertex3f(5.05,0.55,1); glVertex3f(5.05,0.5,1); glVertex3f(5.05,0.5,-1); glColor3f(1,1,1); //right crossbar bottom face glVertex3f(5.05,0.5,-1); glVertex3f(5.05,0.5,1); glVertex3f(5,0.5,1); glVertex3f(5,0.5,-1); glColor3f(1,1,1); //right crossbar top face glVertex3f(5.05,0.55,-1); glVertex3f(5.05,0.55,1); glVertex3f(5,0.55,1); glVertex3f(5,0.55,-1); glColor3f(1,1,1); //left far goal post front face glVertex3f(-5,0.5,-0.95); glVertex3f(-5,0,-0.95); glVertex3f(-5,0,-1); glVertex3f(-5, 0.5, -1); glColor3f(1,1,1); //right far goal post back face glVertex3f(-5.05,0.5,-0.95); glVertex3f(-5.05,0,-0.95); glVertex3f(-5.05,0,-1); glVertex3f(-5.05, 0.5, -1); glColor3f(1,1,1); //right far goal post left face glVertex3f(-5,0.5,-1); glVertex3f(-5,0,-1); glVertex3f(-5.05,0,-1); glVertex3f(-5.05, 0.5, -1); glColor3f(1,1,1); //right far goal post right face glVertex3f(-5.05,0.5,-0.95); glVertex3f(-5.05,0,-0.95); glVertex3f(-5,0,-0.95); glVertex3f(-5, 0.5, -0.95); glColor3f(1,1,1); //left near goal post front face glVertex3f(-5,0.5,0.95); glVertex3f(-5,0,0.95); glVertex3f(-5,0,1); glVertex3f(-5,0.5, 1); glColor3f(1,1,1); //right near goal post back face glVertex3f(-5.05,0.5,0.95); glVertex3f(-5.05,0,0.95); glVertex3f(-5.05,0,1); glVertex3f(-5.05,0.5, 1); glColor3f(1,1,1); //right near goal post left face glVertex3f(-5,0.5,1); glVertex3f(-5,0,1); glVertex3f(-5.05,0,1); glVertex3f(-5.05,0.5, 1); glColor3f(1,1,1); //right near goal post right face glVertex3f(-5.05,0.5,0.95); glVertex3f(-5.05,0,0.95); glVertex3f(-5,0,0.95); glVertex3f(-5,0.5, 0.95); glColor3f(1,1,1); //left crossbar front face glVertex3f(-5,0.55,-1); glVertex3f(-5,0.55,1); glVertex3f(-5,0.5,1); glVertex3f(-5,0.5,-1); glColor3f(1,1,1); //right crossbar back face glVertex3f(-5.05,0.55,-1); glVertex3f(-5.05,0.55,1); glVertex3f(-5.05,0.5,1); glVertex3f(-5.05,0.5,-1); glColor3f(1,1,1); //right crossbar bottom face glVertex3f(-5.05,0.5,-1); glVertex3f(-5.05,0.5,1); glVertex3f(-5,0.5,1); glVertex3f(-5,0.5,-1); glColor3f(1,1,1); //right crossbar top face glVertex3f(-5.05,0.55,-1); glVertex3f(-5.05,0.55,1); glVertex3f(-5,0.55,1); glVertex3f(-5,0.55,-1); glEnd(); // glPopMatrix(); // glPushMatrix(); // glTranslatef(0,0,0); // glutSolidSphere(0.10005,500,30); // glPopMatrix(); }

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• Problems with SAT Collision Detection

  - by DJ AzKai

  I'm doing a project in one of my modules for college in C++ with SFML and I was hoping someone may be able to help me. I'm using a vector of squares and triangles and I am using the SAT collision detection method to see if objects collide and to make the objects respond to the collision appropriately using the MTV(minimum translation vector) Below is my code: //from the main method int main(){ // Create the main window sf::RenderWindow App(sf::VideoMode(800, 600, 32), "SFML OpenGL"); // Create a clock for measuring time elapsed sf::Clock Clock; srand(time(0)); //prepare OpenGL surface for HSR glClearDepth(1.f); glClearColor(0.3f, 0.3f, 0.3f, 0.f); //background colour glEnable(GL_DEPTH_TEST); glDepthMask(GL_TRUE); //// Setup a perspective projection & Camera position glMatrixMode(GL_PROJECTION); glLoadIdentity(); //set up a 3D Perspective View volume //gluPerspective(90.f, 1.f, 1.f, 300.0f);//fov, aspect, zNear, zFar //set up a orthographic projection same size as window //this mease the vertex coordinates are in pixel space glOrtho(0,800,0,600,0,1); // use pixel coordinates // Finally, display rendered frame on screen vector<BouncingThing*> triangles; for(int i = 0; i < 10; i++) { //instantiate each triangle; triangles.push_back(new BouncingTriangle(Vector2f(rand() % 700, rand() % 500), 3)); } vector<BouncingThing*> boxes; for(int i = 0; i < 10; i++) { //instantiate each box; boxes.push_back(new BouncingBox(Vector2f(rand() % 700, rand() % 500), 4)); } CollisionDetection * b = new CollisionDetection(); // Start game loop while (App.isOpen()) { // Process events sf::Event Event; while (App.pollEvent(Event)) { // Close window : exit if (Event.type == sf::Event::Closed) App.close(); // Escape key : exit if ((Event.type == sf::Event::KeyPressed) && (Event.key.code == sf::Keyboard::Escape)) App.close(); } //Prepare for drawing // Clear color and depth buffer glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Apply some transformations glMatrixMode(GL_MODELVIEW); glLoadIdentity(); for(int i = 0; i < 10; i++) { triangles[i]->draw(); boxes[i]->draw(); triangles[i]->update(Vector2f(800,600)); boxes[i]->draw(); boxes[i]->update(Vector2f(800,600)); } for(int j = 0; j < 10; j++) { for(int i = 0; i < 10; i++) { triangles[j]->setCollision(b->CheckCollision(*(triangles[j]),*(boxes[i]))); } } for(int j = 0; j < 10; j++) { for(int i = 0; i < 10; i++) { boxes[j]->setCollision(b->CheckCollision(*(boxes[j]),*(triangles[i]))); } } for(int i = 0; i < triangles.size(); i++) { for(int j = i + 1; j < triangles.size(); j ++) { triangles[j]->setCollision(b->CheckCollision(*(triangles[j]),*(triangles[i]))); } } for(int i = 0; i < triangles.size(); i++) { for(int j = i + 1; j < triangles.size(); j ++) { boxes[j]->setCollision(b->CheckCollision(*(boxes[j]),*(boxes[i]))); } } App.display(); } return EXIT_SUCCESS; } (ignore this line) //from the BouncingThing.cpp BouncingThing::BouncingThing(Vector2f position, int noSides) : pos(position), pi(3.14), radius(3.14), nSides(noSides) { collided = false; if(nSides ==3) { Vector2f vert1 = Vector2f(-12.0f,-12.0f); Vector2f vert2 = Vector2f(0.0f, 12.0f); Vector2f vert3 = Vector2f(12.0f,-12.0f); verts.push_back(vert1); verts.push_back(vert2); verts.push_back(vert3); } else if(nSides == 4) { Vector2f vert1 = Vector2f(-12.0f,12.0f); Vector2f vert2 = Vector2f(12.0f, 12.0f); Vector2f vert3 = Vector2f(12.0f,-12.0f); Vector2f vert4 = Vector2f(-12.0f, -12.0f); verts.push_back(vert1); verts.push_back(vert2); verts.push_back(vert3); verts.push_back(vert4); } velocity.x = ((rand() % 5 + 1) / 3) + 1; velocity.y = ((rand() % 5 + 1) / 3 ) +1; } void BouncingThing::update(Vector2f screenSize) { Transform t; t.rotate(0); for(int i=0;i< verts.size(); i++) { verts[i]=t.transformPoint(verts[i]); } if(pos.x >= screenSize.x || pos.x <= 0) { velocity.x *= -1; } if(pos.y >= screenSize.y || pos.y <= 0) { velocity.y *= -1; } if(collided) { //velocity.x *= -1; //velocity.y *= -1; collided = false; } pos += velocity; } void BouncingThing::setCollision(bool x){ collided = x; } void BouncingThing::draw() { glBegin(GL_POLYGON); glColor3f(0,1,0); for(int i = 0; i < verts.size(); i++) { glVertex2f(pos.x + verts[i].x,pos.y + verts[i].y); } glEnd(); } vector<Vector2f> BouncingThing::getNormals() { vector<Vector2f> normalVerts; if(nSides == 3) { Vector2f ab = Vector2f((verts[1].x + pos.x) - (verts[0].x + pos.x), (verts[1].y + pos.y) - (verts[0].y + pos.y)); ab = flip(ab); ab.x *= -1; normalVerts.push_back(ab); Vector2f bc = Vector2f((verts[2].x + pos.x) - (verts[1].x + pos.x), (verts[2].y + pos.y) - (verts[1].y + pos.y)); bc = flip(bc); bc.x *= -1; normalVerts.push_back(bc); Vector2f ac = Vector2f((verts[2].x + pos.x) - (verts[0].x + pos.x), (verts[2].y + pos.y) - (verts[0].y + pos.y)); ac = flip(ac); ac.x *= -1; normalVerts.push_back(ac); return normalVerts; } if(nSides ==4) { Vector2f ab = Vector2f((verts[1].x + pos.x) - (verts[0].x + pos.x), (verts[1].y + pos.y) - (verts[0].y + pos.y)); ab = flip(ab); ab.x *= -1; normalVerts.push_back(ab); Vector2f bc = Vector2f((verts[2].x + pos.x) - (verts[1].x + pos.x), (verts[2].y + pos.y) - (verts[1].y + pos.y)); bc = flip(bc); bc.x *= -1; normalVerts.push_back(bc); return normalVerts; } } Vector2f BouncingThing::flip(Vector2f v){ float vyTemp = v.x; float vxTemp = v.y * -1; return Vector2f(vxTemp, vyTemp); } (Ignore this line) CollisionDetection::CollisionDetection() { } vector<float> CollisionDetection::bubbleSort(vector<float> w) { int temp; bool finished = false; while (!finished) { finished = true; for (int i = 0; i < w.size()-1; i++) { if (w[i] > w[i+1]) { temp = w[i]; w[i] = w[i+1]; w[i+1] = temp; finished=false; } } } return w; } class Vector{ public: //static int dp_count; static float dot(sf::Vector2f a,sf::Vector2f b){ //dp_count++; return a.x*b.x+a.y*b.y; } static float length(sf::Vector2f a){ return sqrt(a.x*a.x+a.y*a.y); } static Vector2f add(Vector2f a, Vector2f b) { return Vector2f(a.x + b.y, a.y + b.y); } static sf::Vector2f getNormal(sf::Vector2f a,sf::Vector2f b){ sf::Vector2f n; n=a-b; n/=Vector::length(n);//normalise float x=n.x; n.x=n.y; n.y=-x; return n; } }; bool CollisionDetection::CheckCollision(BouncingThing & x, BouncingThing & y) { vector<Vector2f> xVerts = x.getVerts(); vector<Vector2f> yVerts = y.getVerts(); vector<Vector2f> xNormals = x.getNormals(); vector<Vector2f> yNormals = y.getNormals(); int size; vector<float> xRange; vector<float> yRange; for(int j = 0; j < xNormals.size(); j++) { Vector p; for(int i = 0; i < xVerts.size(); i++) { xRange.push_back(p.dot(xNormals[j], Vector2f(xVerts[i].x, xVerts[i].x))); } for(int i = 0; i < yVerts.size(); i++) { yRange.push_back(p.dot(xNormals[j], Vector2f(yVerts[i].x , yVerts[i].y))); } yRange = bubbleSort(yRange); xRange = bubbleSort(xRange); if(xRange[xRange.size() - 1] < yRange[0] || yRange[yRange.size() - 1] < xRange[0]) { return false; } float x3 = Min(xRange[0], yRange[0]); float y3 = Max(xRange[xRange.size() - 1], yRange[yRange.size() - 1]); float length = Max(x3, y3) - Min(x3, y3); } for(int j = 0; j < yNormals.size(); j++) { Vector p; for(int i = 0; i < xVerts.size(); i++) { xRange.push_back(p.dot(yNormals[j], xVerts[i])); } for(int i = 0; i < yVerts.size(); i++) { yRange.push_back(p.dot(yNormals[j], yVerts[i])); } yRange = bubbleSort(yRange); xRange = bubbleSort(xRange); if(xRange[xRange.size() - 1] < yRange[0] || yRange[yRange.size() - 1] < xRange[0]) { return false; } } return true; } float CollisionDetection::Min(float min, float max) { if(max < min) { min = max; } else return min; } float CollisionDetection::Max(float min, float max) { if(min > max) { max = min; } else return min; } On the screen the objects will freeze for a small amount of time before moving off again. However the problem is is that when this happens there are no collisions actually happening and I would really love to find out where the flaw is in the code. If you need any more information/code please don't hesitate to ask and I'll reply as soon as possible Regards, AzKai

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• SQLAuthority News – Professional Development and Community

  - by pinaldave

  I was recently invited by Hyderabad Techies to deliver a keynote for their 16-day online session called TECH THUNDERS. This event has been running from May 15 and will continue up to the end of the month May 30). There would be a total of 30 sessions. In every evening of those 16 day, there will be either one or two sessions from several noted industry experts. It is the same group which has received the Microsoft Community Impact Award as the Best User Group in India as for developers. I have never talked about Professional Development before. Even if this was my first time to do so, I still accepted the wonderful challenge for the sake of the thousands of audience who were expected to attend this online event. Time is of the essence; I had 15 minutes to deliver the keynote and open the event. The reason why I was nervous was because I had to cover precisely only 15 minutes- no more, no less. If I had an hour, I would have been very confident because I knew I could do a good job for sure. However, I still needed to open the event as great as it can be even if the time was short. I finally created a 6-slide small presentation. In reality, there were only two pages which had the main contents of my keynote, and the remaining slides were just wrappers and decors. You can download the complete slide deck from here. The image used in the slide deck is a curtsy of blog reader Roger Smith who sent it to me. The slide in which I spent a good amount of time is the slide which talks about Professional Development. The content of the slide is as follows: Today, Technology and You Keep your eyes, ears and senses open – Stay Active! You are not the first one who faced the problem – Search Online! Learn the web – Blogs, Forums and Friends! Trust the Technology, Not Print – Test Everything! Community and You! I had a very little time creating the slide deck as I was busy the whole day doing the Advanced SQL Server Training. I had put together these slides during the tea/coffee break of my session. Though it was just a six-bullet point, I had received quite a few emails right after keynote requesting me to talk more about this subject and share the details of my slide deck. I have talked with the event organizer and he will put the keynote online very soon. The subject of the talk is very simple; it revolves around the community. Time has changed, and Internet has come a long way from where it was many years ago. Now that we are all connected, help via the Internet and useful software is easily available around us. In fact, RSS, Newletters and few other technologies have progressed so much that the help through news is now being delivered to our door steps, instead of going out and seeking them. Sometimes, a simple search online solves a lot of problems of many developers. The community is now the first stop for any developer when he or she needs help or just wants to hang around and share some thoughts. I strongly suggest everybody to be a part of the Tech Community. Be it online, offline community or just a local user group, I strongly advise all of you to get involved. I am active in the Community, and I must say I recommend getting drawn into it. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: MVP, Pinal Dave, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL User Group, SQLAuthority News, T SQL, Technology Tagged: Community

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• IntelliTrace As a Learning Tool for MVC2 in a VS2010 Project

  - by Sam Abraham

  IntelliTrace is a new feature in Visual Studio 2010 Ultimate Edition. I see this valuable tool as a “Program Execution Recorder” that captures information about events and calls taking place as soon as we hit the VS2010 play (Start Debugging) button or the F5 key. Many online resources already discuss IntelliTrace and the benefit it brings to both developers and testers alike so I see no value of just repeating this information.  In this brief blog entry, I would like to share with you how I will be using IntelliTrace in my upcoming talk at the Ft Lauderdale ArcSig .Net User Group Meeting on April 20th 2010 (check http://www.fladotnet.com for more information), as a learning tool to demonstrate the internals of the lifecycle of an MVC2 application.  I will also be providing some helpful links that cover IntelliTrace in more detail at the end of my article for reference. IntelliTrace is setup by default to only capture execution events. Microsoft did such a great job on optimizing its recording process that I haven’t even felt the slightest performance hit with IntelliTrace running as I was debugging my solutions and projects.  For my purposes here however, I needed to capture more information beyond execution events, so I turned on the option for capturing calls in addition to events as shown in Figures 1 and 2. Changing capture options will require us to stop our debugging session and start over for the new settings to take place. Figure 1 – Access IntelliTrace options via the Tools->Options menu items Figure 2 – Change IntelliTrace Options to capture call information as well as events Notice the warning with regards to potentially degrading performance when selecting to capture call information in addition to the default events-only setting. I have found this warning to be sure true. My subsequent tests showed slowness in page load times compared to rendering those same exact pages with the “event-only” option selected. Execution recording is auto-started along with the new debugging session of our project. At this point, we can simply interact with the application and continue executing normally until we decide to “playback” the code we have executed so far.  For code replay, first step is to “break” the current execution as show in Figure 3.   Figure 3 – Break to replay recording A few tries later, I found a good process to quickly find and demonstrate the MVC2 page lifecycle. First-off, we start with the event view as shown in Figure 4 until we find an interesting event that needs further studying.  Figure 4 – Going through IntelliTrace’s events and picking as specific entry of interest We now can, for instance, study how the highlighted HTTP GET request is being handled, by clicking on the “Calls View” for that particular event. Notice that IntelliTrace shows us all calls that took place in servicing that GET request. Double clicking on any call takes us to a more granular view of the call stack within that clicked call, up until getting to a specific line of code where we can do a line-by-line replay of the execution from that point onwards using F10 or F11 just like our typical good old VS2008 debugging helped us accomplish. Figure 5 – switching to call view on an event of interest Figure 6 – Double clicking on call shows a more granular view of the call stack. In conclusion, the introduction of IntelliTrace as a new addition to the VS developers’ tool arsenal enhances development and debugging experience and effectively tackles the “no-repro” problem. It will also hopefully enhance my audience’s experience listening to me speaking about  an MVC2 page lifecycle which I can now easily visually demonstrate, thereby improving the probability of keeping everybody awake a little longer. IntelliTrace References: http://msdn.microsoft.com/en-us/magazine/ee336126.aspx http://msdn.microsoft.com/en-us/library/dd264944(VS.100).aspx

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• Save the Date - Oracle Partner Community Forum: Exadata, Exalogic and Manageability, Vienna, 23-24 April 2013

  - by Javier Puerta

  Hardware and Software Engineered to Work Together .Ritu { font-family: Arial, Helvetica, sans-serif; } .Ritu { font-family: Arial, Helvetica, sans-serif; } .Ritu { font-family: Arial, Helvetica, sans-serif; } body,td,th { font-family: Arial, Helvetica, sans-serif; font-size: x-small; } .color { color: #F00; } .c { color: #F00; } .c { color: #F00; } .c { color: #000; font-size: xx-small; } .c a { color: #F00; } .c { color: #F00; } .cl { color: #F00; } .b { color: #000; font-size: xx-small; } .i { font-style: italic; } .i { font-style: italic; } .i { font-style: italic; } .i { font-style: italic; } .i { font-style: italic; } .c { color: #F00; font-size: small; } .b { font-weight: bold; font-size: x-small; } .c { color: #F00; font-size: x-small; } .clr { color: #F00; } .c { color: #F00; } inside the Click Here The order you must follow to make the colored link appear in browsers. If not the default window link will appear 1. Select the word you want to use for the link 2. Select the desired color, Red, Black, etc 3. Select bold if necessary ___________________________________________________________________________________________________________________ Templates use two sizes of fonts and the sans-serif font tag for the email. All Fonts should be (Arial, Helvetica, sans-serif) tags Normal size reading body fonts should be set to the size of 2. Small font sizes should be set to 1 !!!!!!!DO NOT USE ANY OTHER SIZE FONT FOR THE EMAILS!!!!!!!! ___________________________________________________________________________________________________________________ -- Oracle PartnerNetwork | Account | Feedback SAVE THE DATE ORACLE PARTNER COMMUNITY FORUM: EXADATA, EXALOGIC AND MANAGEABILITY 23-24 APRIL 2013, VIENNA, AUSTRIA The 2013 event expands its scope to cover all the building blocks of the Cloud infrastructure: Exadata, Exalogic and Manageability! Dear partner I am delighted to announce the 2013 edition of the Exadata, Exalogic and Manageability Partner Community Forum for EMEA partners which will take place in Vienna, Austria, on April 23-24, 2013. After the experience of last year where we ran a joint Exadata and Manageability event, we received requests from many of you to add also Exalogic to the scope of the forum, and this way to cover the complete infrastructure architecture on the Exa platform. The continued market adoption of Exadata and Exalogic is being paralleled by a growth in the rate of projects sold and implemented by partners. Sharing customer cases and best-practices presented by other partners constitutes the core of this event. If you want to present an experience of your company around Exadata, Exalogic or Manageability that can be a learning experience for other partners, we still have some slots in the agenda. (Please contact Javier Puerta if you want to present.) Attending the Community Forum you will also have the opportunity to get Oracle’s insight on new products and market trends. And, of course, interact with the Oracle executives responsible for the Exadata, Exalogic and Manageability business. The atmosphere of beautiful Vienna will be the scenario of the event. Detailed venue and hotel booking information will be sent to you in January. Don't miss out on attending this key event! Save the date now - 23 & 24 April 2013, and watch out for your formal invitation coming soon. Kind regards, Javier Puerta Core Technology Partner Programs, Oracle EMEA E-Mail: [email protected] Jürgen Kress SOA Partner Adoption Oracle EMEA E-Mail: [email protected] Copyright © 2012, Oracle and/or its affiliates. All rights reserved. Contact PBC | Legal Notices and Terms of Use | Privacy Oracle Corporation - Worldwide Headquarters, 500 Oracle Parkway, OPL - E-mail Services, Redwood Shores, CA 94065, United States

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• Save the Date - Oracle Partner Community Forum: Exadata, Exalogic and Manageability, Vienna, 23-24 April 2013

  - by Javier Puerta

  Hardware and Software Engineered to Work Together .Ritu { font-family: Arial, Helvetica, sans-serif; } .Ritu { font-family: Arial, Helvetica, sans-serif; } .Ritu { font-family: Arial, Helvetica, sans-serif; } body,td,th { font-family: Arial, Helvetica, sans-serif; font-size: x-small; } .color { color: #F00; } .c { color: #F00; } .c { color: #F00; } .c { color: #000; font-size: xx-small; } .c a { color: #F00; } .c { color: #F00; } .cl { color: #F00; } .b { color: #000; font-size: xx-small; } .i { font-style: italic; } .i { font-style: italic; } .i { font-style: italic; } .i { font-style: italic; } .i { font-style: italic; } .c { color: #F00; font-size: small; } .b { font-weight: bold; font-size: x-small; } .c { color: #F00; font-size: x-small; } .clr { color: #F00; } .c { color: #F00; } inside the Click Here The order you must follow to make the colored link appear in browsers. If not the default window link will appear 1. Select the word you want to use for the link 2. Select the desired color, Red, Black, etc 3. Select bold if necessary ___________________________________________________________________________________________________________________ Templates use two sizes of fonts and the sans-serif font tag for the email. All Fonts should be (Arial, Helvetica, sans-serif) tags Normal size reading body fonts should be set to the size of 2. Small font sizes should be set to 1 !!!!!!!DO NOT USE ANY OTHER SIZE FONT FOR THE EMAILS!!!!!!!! ___________________________________________________________________________________________________________________ -- Oracle PartnerNetwork | Account | Feedback SAVE THE DATE ORACLE PARTNER COMMUNITY FORUM: EXADATA, EXALOGIC AND MANAGEABILITY 23-24 APRIL 2013, VIENNA, AUSTRIA The 2013 event expands its scope to cover all the building blocks of the Cloud infrastructure: Exadata, Exalogic and Manageability! Dear partner I am delighted to announce the 2013 edition of the Exadata, Exalogic and Manageability Partner Community Forum for EMEA partners which will take place in Vienna, Austria, on April 23-24, 2013. After the experience of last year where we ran a joint Exadata and Manageability event, we received requests from many of you to add also Exalogic to the scope of the forum, and this way to cover the complete infrastructure architecture on the Exa platform. The continued market adoption of Exadata and Exalogic is being paralleled by a growth in the rate of projects sold and implemented by partners. Sharing customer cases and best-practices presented by other partners constitutes the core of this event. If you want to present an experience of your company around Exadata, Exalogic or Manageability that can be a learning experience for other partners, we still have some slots in the agenda. (Please contact Javier Puerta if you want to present.) Attending the Community Forum you will also have the opportunity to get Oracle’s insight on new products and market trends. And, of course, interact with the Oracle executives responsible for the Exadata, Exalogic and Manageability business. The atmosphere of beautiful Vienna will be the scenario of the event. Detailed venue and hotel booking information will be sent to you in January. Don't miss out on attending this key event! Save the date now - 23 & 24 April 2013, and watch out for your formal invitation coming soon. Kind regards, Javier Puerta Core Technology Partner Programs, Oracle EMEA E-Mail: [email protected] Jürgen Kress SOA Partner Adoption Oracle EMEA E-Mail: [email protected] Copyright © 2012, Oracle and/or its affiliates. All rights reserved. Contact PBC | Legal Notices and Terms of Use | Privacy Oracle Corporation - Worldwide Headquarters, 500 Oracle Parkway, OPL - E-mail Services, Redwood Shores, CA 94065, United States

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• Windows 8 Camp&ndash;Ways to Prepare

  - by Lori Lalonde

  When Windows 8 was announced at the BUILD conference back in September, it created quite a buzz among the developer community. By the spring of 2012,  Windows 8 Developer Camps started popping up everywhere imaginable. I received a lot of questions from CTTDNUG members about whether or not we would be hosting one locally. If you recall my post about the Windows Phone/Azure Developer Workshop that CTTDNUG hosted back in March, you’ll remember that the biggest hurdle to overcome when planning this type of event was finding the right venue. It took some time, but I finally found a venue that was available and provided the prerequisites needed to ensure this camp is a success. I am very excited that CTTDNUG will be hosting a Windows 8 Camp this summer in the Kitchener/Waterloo area. In fact, it’s coming up in less than 2 weeks. Clearly other developers are excited as well, because our registration numbers show that the event is already 70% full! On top of that, I was fortunate enough to also book two well-known evangelists to present and teach at this full day developer camp: Andrei Marukovich and Atley Hunter. This was the icing on the cake. With the content provided by Microsoft, and two local experts that live and breathe Windows 8 development, I know that I, along with other developers that attend this event, will have the opportunity to maximize our learning potential and hit the ground running. If you plan on attending a Windows 8 Developer Camp soon, and want to ensure you get the most “bang for your buck” (figuratively speaking, since these camps are free), there are some things you can do to prepare before the big day: 1) Install the prerequisites on your own device before the big day I can’t stress this enough. Otherwise, you will be spending valuable time during the hands-on period downloading and installing what is needed, rather than digging into the development and using that time to ask the experts on-hand about programming challenges, issues, questions you may have with respect to your development. Prerequisites: Windows 8 Release Preview Visual Studio 2012 RC Download the Windows 8 SDK Samples 2) Purchase, download, and read Charles Petzold’s newest book:  Programming Windows 6th Edition This is a great introduction to the type of content you will be learning about during the camp. Doing some light reading beforehand might raise some questions about the concepts discussed in the book, which will give you the opportunity to write them down and bring them with you to the camp. The experts on hand will be able to answer them for you. 3) Make use of the freebies that are available Telerik has recently released a preview of their RadControls for Metro. You can sign up to receive a license code to give you access to install the preview for free and start playing around with it. Syncfusion also offers a free download of their Metro Studio package, which is a collection of metro style icons that you can customize and use in your own applications. Last but not least, once you’ve installed the Windows 8 Release Preview on your own device, go to the Windows 8 Store and download a handful of the free apps that are available. Testing out other Metro apps may give you ideas of what you can do in your own apps and analyze what features you like: application flow, type of animations used, concepts that were leveraged, how live tiles were used, etc. I hope you found these tips to be useful as you embark on a new development journey! Although this post focused on how to prepare for a Windows 8 camp, the same ideas are there whichever developer camp/workshop/event you attend. Learning does not begin and end on the day of the event. Attending a developer camp is just one step of many to master whatever technology you are interested in. It is a continuous process, which is fully maximized when you do your homework beforehand, actively participate during,  and follow up by putting what you learned to practice afterwards. Happy coding!

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• C# 5 Async, Part 2: Asynchrony Today

  - by Reed

  The .NET Framework has always supported asynchronous operations.  However, different mechanisms for supporting exist throughout the framework.  While there are at least three separate asynchronous patterns used through the framework, only the latest is directly usable with the new Visual Studio Async CTP.  Before delving into details on the new features, I will talk about existing asynchronous code, and demonstrate how to adapt it for use with the new pattern. The first asynchronous pattern used in the .NET framework was the Asynchronous Programming Model (APM).  This pattern was based around callbacks.  A method is used to start the operation.  It typically is named as BeginSomeOperation.  This method is passed a callback defined as an AsyncCallback, and returns an object that implements IAsyncResult.  Later, the IAsyncResult is used in a call to a method named EndSomeOperation, which blocks until completion and returns the value normally directly returned from the synchronous version of the operation.  Often, the EndSomeOperation call would be called from the callback function passed, which allows you to write code that never blocks. While this pattern works perfectly to prevent blocking, it can make quite confusing code, and be difficult to implement.  For example, the sample code provided for FileStream’s BeginRead/EndRead methods is not simple to understand.  In addition, implementing your own asynchronous methods requires creating an entire class just to implement the IAsyncResult. Given the complexity of the APM, other options have been introduced in later versions of the framework.  The next major pattern introduced was the Event-based Asynchronous Pattern (EAP).  This provides a simpler pattern for asynchronous operations.  It works by providing a method typically named SomeOperationAsync, which signals its completion via an event typically named SomeOperationCompleted. The EAP provides a simpler model for asynchronous programming.  It is much easier to understand and use, and far simpler to implement.  Instead of requiring a custom class and callbacks, the standard event mechanism in C# is used directly.  For example, the WebClient class uses this extensively.  A method is used, such as DownloadDataAsync, and the results are returned via the DownloadDataCompleted event. While the EAP is far simpler to understand and use than the APM, it is still not ideal.  By separating your code into method calls and event handlers, the logic of your program gets more complex.  It also typically loses the ability to block until the result is received, which is often useful.  Blocking often requires writing the code to block by hand, which is error prone and adds complexity. As a result, .NET 4 introduced a third major pattern for asynchronous programming.  The Task<T> class introduced a new, simpler concept for asynchrony.  Task and Task<T> effectively represent an operation that will complete at some point in the future.  This is a perfect model for thinking about asynchronous code, and is the preferred model for all new code going forward.  Task and Task<T> provide all of the advantages of both the APM and the EAP models – you have the ability to block on results (via Task.Wait() or Task<T>.Result), and you can stay completely asynchronous via the use of Task Continuations.  In addition, the Task class provides a new model for task composition and error and cancelation handling.  This is a far superior option to the previous asynchronous patterns. The Visual Studio Async CTP extends the Task based asynchronous model, allowing it to be used in a much simpler manner.  However, it requires the use of Task and Task<T> for all operations.

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