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  • Constructor should generally not call methods

    - by Stefano Borini
    I described to a colleague why a constructor calling a method can be an antipattern. example (in my rusty C++) class C { public : C(int foo); void setFoo(int foo); private: int foo; } C::C(int foo) { setFoo(foo); } void C::setFoo(int foo) { this->foo = foo } I would like to motivate better this fact through your additional contribute. If you have examples, book references, blog pages, or names of principles, they would be very welcome. Edit: I'm talking in general, but we are coding in python.

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  • Bubble shooter search alghoritm

    - by Fofole
    So I have a Matrix of NxM. At a given position (for ex. [2][5]) I have a value which represents a color. If there is nothing at that point the value is -1. What I need to do is after I add a new point, to check all his neighbours with the same color value and if there are more than 2, set them all to -1. If what I said doesn't make sense what I'm trying to do is an alghoritm which I use to destroy all the same color bubbles from my screen, where the bubbles are memorized in a matrix where -1 means no bubble and {0,1,2,...} represent that there is a bubble with a specific color. This is what I tried and failed: public class Testing { static private int[][] gameMatrix= {{3, 3, 4, 1, 1, 2, 2, 2, 0, 0}, {1, 4, 1, 4, 2, 2, 1, 3, 0, 0}, {2, 2, 4, 4, 3, 1, 2, 4, 0, 0}, {0, 1, 2, 3, 4, 1, 0, 0, 0, 0}, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, }; static int Rows=6; static int Cols=10; static int count; static boolean[][] visited=new boolean[15][15]; static int NOCOLOR = -1; static int color = 1; public static void dfs(int r, int c, int color, boolean set) { for(int dr = -1; dr <= 1; dr++) for(int dc = -1; dc <= 1; dc++) if(!(dr == 0 && dc == 0) && ok(r+dr, c+dc)) { int nr = r+dr; int nc = c+dc; // if it is the same color and we haven't visited this location before if(gameMatrix[nr][nc] == color && !visited[nr][nc]) { visited[nr][nc] = true; count++; dfs(nr, nc, color, set); if(set) { gameMatrix[nr][nc] = NOCOLOR; } } } } static boolean ok(int r, int c) { return r >= 0 && r < Rows && c >= 0 && c < Cols; } static void showMatrix(){ for(int i = 0; i < gameMatrix.length; i++) { System.out.print("["); for(int j = 0; j < gameMatrix[0].length; j++) { System.out.print(" " + gameMatrix[i][j]); } System.out.println(" ]"); } System.out.println(); } static void putValue(int value,int row,int col){ gameMatrix[row][col]=value; } public static void main(String[] args){ System.out.println("Initial Matrix:"); putValue(1, 4, 1); putValue(1, 5, 1); showMatrix(); for(int n = 0; n < 15; n++) for(int m = 0; m < 15; m++) visited[n][m] = false; //reset count count = 0; //dfs(bubbles.get(i).getRow(), bubbles.get(i).getCol(), color, false); // get the contiguous count dfs(5,1,color,false); //if there are more than 2 set the color to NOCOLOR for(int n = 0; n < 15; n++) for(int m = 0; m < 15; m++) visited[n][m] = false; if(count > 2) { //dfs(bubbles.get(i).getRow(), bubbles.get(i).getCol(), color, true); dfs(5,1,color,true); } System.out.println("Matrix after dfs:"); showMatrix(); } }

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  • Windows Phone 7 : Dragging and flicking UI controls

    - by TechTwaddle
    Who would want to flick and drag UI controls!? There might not be many use cases but I think some concepts here are worthy of a post. So we will create a simple silverlight application for windows phone 7, containing a canvas element on which we’ll place a button control and an image and then, as the title says, drag and flick the controls. Here’s Mainpage.xaml, <Grid x:Name="LayoutRoot" Background="Transparent">   <Grid.RowDefinitions>     <RowDefinition Height="Auto"/>     <RowDefinition Height="*"/>   </Grid.RowDefinitions>     <!--TitlePanel contains the name of the application and page title-->   <StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,17,0,28">     <TextBlock x:Name="ApplicationTitle" Text="KINETICS" Style="{StaticResource PhoneTextNormalStyle}"/>     <TextBlock x:Name="PageTitle" Text="drag and flick" Margin="9,-7,0,0" Style="{StaticResource PhoneTextTitle1Style}"/>   </StackPanel>     <!--ContentPanel - place additional content here-->   <Grid x:Name="ContentPanel" Grid.Row="1" >     <Canvas x:Name="MainCanvas" HorizontalAlignment="Stretch" VerticalAlignment="Stretch">       <Canvas.Background>         <LinearGradientBrush StartPoint="0 0" EndPoint="0 1">           <GradientStop Offset="0" Color="Black"/>           <GradientStop Offset="1.5" Color="BlanchedAlmond"/>         </LinearGradientBrush>       </Canvas.Background>     </Canvas>   </Grid> </Grid> the second row in the main grid contains a canvas element, MainCanvas, with its horizontal and vertical alignment set to stretch so that it occupies the entire grid. The canvas background is a linear gradient brush starting with Black and ending with BlanchedAlmond. We’ll add the button and image control to this canvas at run time. Moving to Mainpage.xaml.cs the Mainpage class contains the following members, public partial class MainPage : PhoneApplicationPage {     Button FlickButton;     Image FlickImage;       FrameworkElement ElemToMove = null;     double ElemVelX, ElemVelY;       const double SPEED_FACTOR = 60;       DispatcherTimer timer; FlickButton and FlickImage are the controls that we’ll add to the canvas. ElemToMove, ElemVelX and ElemVelY will be used by the timer callback to move the ui control. SPEED_FACTOR is used to scale the velocities of ui controls. Here’s the Mainpage constructor, // Constructor public MainPage() {     InitializeComponent();       AddButtonToCanvas();       AddImageToCanvas();       timer = new DispatcherTimer();     timer.Interval = TimeSpan.FromMilliseconds(35);     timer.Tick += new EventHandler(OnTimerTick); } We’ll look at those AddButton and AddImage functions in a moment. The constructor initializes a timer which fires every 35 milliseconds, this timer will be started after the flick gesture completes with some inertia. Back to AddButton and AddImage functions, void AddButtonToCanvas() {     LinearGradientBrush brush;     GradientStop stop1, stop2;       Random rand = new Random(DateTime.Now.Millisecond);       FlickButton = new Button();     FlickButton.Content = "";     FlickButton.Width = 100;     FlickButton.Height = 100;       brush = new LinearGradientBrush();     brush.StartPoint = new Point(0, 0);     brush.EndPoint = new Point(0, 1);       stop1 = new GradientStop();     stop1.Offset = 0;     stop1.Color = Colors.White;       stop2 = new GradientStop();     stop2.Offset = 1;     stop2.Color = (Application.Current.Resources["PhoneAccentBrush"] as SolidColorBrush).Color;       brush.GradientStops.Add(stop1);     brush.GradientStops.Add(stop2);       FlickButton.Background = brush;       Canvas.SetTop(FlickButton, rand.Next(0, 400));     Canvas.SetLeft(FlickButton, rand.Next(0, 200));       MainCanvas.Children.Add(FlickButton);       //subscribe to events     FlickButton.ManipulationDelta += new EventHandler<ManipulationDeltaEventArgs>(OnManipulationDelta);     FlickButton.ManipulationCompleted += new EventHandler<ManipulationCompletedEventArgs>(OnManipulationCompleted); } this function is basically glorifying a simple task. After creating the button and setting its height and width, its background is set to a linear gradient brush. The direction of the gradient is from top towards bottom and notice that the second stop color is the PhoneAccentColor, which changes along with the theme of the device. The line,     stop2.Color = (Application.Current.Resources["PhoneAccentBrush"] as SolidColorBrush).Color; does the magic of extracting the PhoneAccentBrush from application’s resources, getting its color and assigning it to the gradient stop. AddImage function is straight forward in comparison, void AddImageToCanvas() {     Random rand = new Random(DateTime.Now.Millisecond);       FlickImage = new Image();     FlickImage.Source = new BitmapImage(new Uri("/images/Marble.png", UriKind.Relative));       Canvas.SetTop(FlickImage, rand.Next(0, 400));     Canvas.SetLeft(FlickImage, rand.Next(0, 200));       MainCanvas.Children.Add(FlickImage);       //subscribe to events     FlickImage.ManipulationDelta += new EventHandler<ManipulationDeltaEventArgs>(OnManipulationDelta);     FlickImage.ManipulationCompleted += new EventHandler<ManipulationCompletedEventArgs>(OnManipulationCompleted); } The ManipulationDelta and ManipulationCompleted handlers are same for both the button and the image. OnManipulationDelta() should look familiar, a similar implementation was used in the previous post, void OnManipulationDelta(object sender, ManipulationDeltaEventArgs args) {     FrameworkElement Elem = sender as FrameworkElement;       double Left = Canvas.GetLeft(Elem);     double Top = Canvas.GetTop(Elem);       Left += args.DeltaManipulation.Translation.X;     Top += args.DeltaManipulation.Translation.Y;       //check for bounds     if (Left < 0)     {         Left = 0;     }     else if (Left > (MainCanvas.ActualWidth - Elem.ActualWidth))     {         Left = MainCanvas.ActualWidth - Elem.ActualWidth;     }       if (Top < 0)     {         Top = 0;     }     else if (Top > (MainCanvas.ActualHeight - Elem.ActualHeight))     {         Top = MainCanvas.ActualHeight - Elem.ActualHeight;     }       Canvas.SetLeft(Elem, Left);     Canvas.SetTop(Elem, Top); } all it does is calculate the control’s position, check for bounds and then set the top and left of the control. OnManipulationCompleted() is more interesting because here we need to check if the gesture completed with any inertia and if it did, start the timer and continue to move the ui control until it comes to a halt slowly, void OnManipulationCompleted(object sender, ManipulationCompletedEventArgs args) {     FrameworkElement Elem = sender as FrameworkElement;       if (args.IsInertial)     {         ElemToMove = Elem;           Debug.WriteLine("Linear VelX:{0:0.00}  VelY:{1:0.00}", args.FinalVelocities.LinearVelocity.X,             args.FinalVelocities.LinearVelocity.Y);           ElemVelX = args.FinalVelocities.LinearVelocity.X / SPEED_FACTOR;         ElemVelY = args.FinalVelocities.LinearVelocity.Y / SPEED_FACTOR;           timer.Start();     } } ManipulationCompletedEventArgs contains a member, IsInertial, which is set to true if the manipulation was completed with some inertia. args.FinalVelocities.LinearVelocity.X and .Y will contain the velocities along the X and Y axis. We need to scale down these values so they can be used to increment the ui control’s position sensibly. A reference to the ui control is stored in ElemToMove and the velocities are stored as well, these will be used in the timer callback to access the ui control. And finally, we start the timer. The timer callback function is as follows, void OnTimerTick(object sender, EventArgs e) {     if (null != ElemToMove)     {         double Left, Top;         Left = Canvas.GetLeft(ElemToMove);         Top = Canvas.GetTop(ElemToMove);           Left += ElemVelX;         Top += ElemVelY;           //check for bounds         if (Left < 0)         {             Left = 0;             ElemVelX *= -1;         }         else if (Left > (MainCanvas.ActualWidth - ElemToMove.ActualWidth))         {             Left = MainCanvas.ActualWidth - ElemToMove.ActualWidth;             ElemVelX *= -1;         }           if (Top < 0)         {             Top = 0;             ElemVelY *= -1;         }         else if (Top > (MainCanvas.ActualHeight - ElemToMove.ActualHeight))         {             Top = MainCanvas.ActualHeight - ElemToMove.ActualHeight;             ElemVelY *= -1;         }           Canvas.SetLeft(ElemToMove, Left);         Canvas.SetTop(ElemToMove, Top);           //reduce x,y velocities gradually         ElemVelX *= 0.9;         ElemVelY *= 0.9;           //when velocities become too low, break         if (Math.Abs(ElemVelX) < 1.0 && Math.Abs(ElemVelY) < 1.0)         {             timer.Stop();             ElemToMove = null;         }     } } if ElemToMove is not null, we get the top and left values of the control and increment the values with their X and Y velocities. Check for bounds, and if the control goes out of bounds we reverse its velocity. Towards the end, the velocities are reduced by 10% every time the timer callback is called, and if the velocities reach too low values the timer is stopped and ElemToMove is made null. Here’s a short video of the program, the video is a little dodgy because my display driver refuses to run the animations smoothly. The flicks aren’t always recognised but the program should run well on an actual device (or a pc with better configuration), You can download the source code from here: ButtonDragAndFlick.zip

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  • Changing Silverlight application themes at runtime

    We have received a lot of questions how can the application theme be changed at run time. The most important thing here to mark is that each time the application theme is changed all the controls should be re-drawn. Without going into too much detail, we could explain the application themes as a mechanism to replace the content of the Generic.xaml file in every loaded Telerik assembly at runtime. This does not affect the controls that already have default style applied, hence the need to create new instances. Because in the Silverlight applications the RootVisual cannot be changed at run time, we need a way to reset the application UI. The following code is in App.xaml.cs. private void Application_Startup(object sender, StartupEventArgs e)     {           // Before:           // this.RootVisual = new MainPage();            this.RootVisual = new Grid();         this.ResetRootVisual();     }        public void ResetRootVisual()     {         var rootVisual = Application.Current.RootVisual as Grid;         rootVisual.Children.Clear();         rootVisual.Children.Add(new MainPage());     }   In Application_Startup() instead of creating new MainPage UserControl instance as RootVisual, we create a new Grid panel, that will contain the MainPage UserControl. In the ResetRootVisual() method we create the instance of MainPage and add it to the RootVisual panel. Then we have to create a method in the code behind which will set StyleManager.ApplicationTheme and then will call the ResetRootVisual() method: private void ChangeApplicationTheme(Theme theme) {     StyleManager.ApplicationTheme = theme;     (Application.Current as App).ResetRootVisual(); }   Here you can find an example which illustrates the described implementation of a Silverlight theme. For more information please refer to Teleriks online demos for Silverlight, the demos for WPF and help documentation for WPF and help documentation for Silverlight. Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Optimizing a thread safe Java NIO / Serialization / FIFO Queue [migrated]

    - by trialcodr
    I've written a thread safe, persistent FIFO for Serializable items. The reason for reinventing the wheel is that we simply can't afford any third party dependencies in this project and want to keep this really simple. The problem is it isn't fast enough. Most of it is undoubtedly due to reading and writing directly to disk but I think we should be able to squeeze a bit more out of it anyway. Any ideas on how to improve the performance of the 'take'- and 'add'-methods? /** * <code>DiskQueue</code> Persistent, thread safe FIFO queue for * <code>Serializable</code> items. */ public class DiskQueue<ItemT extends Serializable> { public static final int EMPTY_OFFS = -1; public static final int LONG_SIZE = 8; public static final int HEADER_SIZE = LONG_SIZE * 2; private InputStream inputStream; private OutputStream outputStream; private RandomAccessFile file; private FileChannel channel; private long offs = EMPTY_OFFS; private long size = 0; public DiskQueue(String filename) { try { boolean fileExists = new File(filename).exists(); file = new RandomAccessFile(filename, "rwd"); if (fileExists) { size = file.readLong(); offs = file.readLong(); } else { file.writeLong(size); file.writeLong(offs); } } catch (FileNotFoundException e) { throw new RuntimeException(e); } catch (IOException e) { throw new RuntimeException(e); } channel = file.getChannel(); inputStream = Channels.newInputStream(channel); outputStream = Channels.newOutputStream(channel); } /** * Add item to end of queue. */ public void add(ItemT item) { try { synchronized (this) { channel.position(channel.size()); ObjectOutputStream s = new ObjectOutputStream(outputStream); s.writeObject(item); s.flush(); size++; file.seek(0); file.writeLong(size); if (offs == EMPTY_OFFS) { offs = HEADER_SIZE; file.writeLong(offs); } notify(); } } catch (IOException e) { throw new RuntimeException(e); } } /** * Clears overhead by moving the remaining items up and shortening the file. */ public synchronized void defrag() { if (offs > HEADER_SIZE && size > 0) { try { long totalBytes = channel.size() - offs; ByteBuffer buffer = ByteBuffer.allocateDirect((int) totalBytes); channel.position(offs); for (int bytes = 0; bytes < totalBytes;) { int res = channel.read(buffer); if (res == -1) { throw new IOException("Failed to read data into buffer"); } bytes += res; } channel.position(HEADER_SIZE); buffer.flip(); for (int bytes = 0; bytes < totalBytes;) { int res = channel.write(buffer); if (res == -1) { throw new IOException("Failed to write buffer to file"); } bytes += res; } offs = HEADER_SIZE; file.seek(LONG_SIZE); file.writeLong(offs); file.setLength(HEADER_SIZE + totalBytes); } catch (IOException e) { throw new RuntimeException(e); } } } /** * Returns the queue overhead in bytes. */ public synchronized long overhead() { return (offs == EMPTY_OFFS) ? 0 : offs - HEADER_SIZE; } /** * Returns the first item in the queue, blocks if queue is empty. */ public ItemT peek() throws InterruptedException { block(); synchronized (this) { if (offs != EMPTY_OFFS) { return readItem(); } } return peek(); } /** * Returns the number of remaining items in queue. */ public synchronized long size() { return size; } /** * Removes and returns the first item in the queue, blocks if queue is empty. */ public ItemT take() throws InterruptedException { block(); try { synchronized (this) { if (offs != EMPTY_OFFS) { ItemT result = readItem(); size--; offs = channel.position(); file.seek(0); if (offs == channel.size()) { truncate(); } file.writeLong(size); file.writeLong(offs); return result; } } return take(); } catch (IOException e) { throw new RuntimeException(e); } } /** * Throw away all items and reset the file. */ public synchronized void truncate() { try { offs = EMPTY_OFFS; file.setLength(HEADER_SIZE); size = 0; } catch (IOException e) { throw new RuntimeException(e); } } /** * Block until an item is available. */ protected void block() throws InterruptedException { while (offs == EMPTY_OFFS) { try { synchronized (this) { wait(); file.seek(LONG_SIZE); offs = file.readLong(); } } catch (IOException e) { throw new RuntimeException(e); } } } /** * Read and return item. */ @SuppressWarnings("unchecked") protected ItemT readItem() { try { channel.position(offs); return (ItemT) new ObjectInputStream(inputStream).readObject(); } catch (ClassNotFoundException e) { throw new RuntimeException(e); } catch (IOException e) { throw new RuntimeException(e); } } }

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  • Breakout ball collision detection, bouncing against the walls [solved]

    - by Sri Harsha Chilakapati
    I'm currently trying to program a breakout game to distribute it as an example game for my own game engine. http://game-engine-for-java.googlecode.com/ But the problem here is that I can't get the bouncing condition working properly. Here's what I'm using. public void collision(GObject other){ if (other instanceof Bat || other instanceof Block){ bounce(); } else if (other instanceof Stone){ other.destroy(); bounce(); } //Breakout.HIT.play(); } And here's by bounce() method public void bounce(){ boolean left = false; boolean right = false; boolean up = false; boolean down = false; if (dx < 0) { left = true; } else if (dx > 0) { right = true; } if (dy < 0) { up = true; } else if (dy > 0) { down = true; } if (left && up) { dx = -dx; } if (left && down) { dy = -dy; } if (right && up) { dx = -dx; } if (right && down) { dy = -dy; } } The ball bounces the bat and blocks but when the block is on top of the ball, it won't bounce and moves upwards out of the game. What I'm missing? Is there anything to implement? Please help me.. Thanks EDIT: Have changed the bounce method. public void bounce(GObject other){ //System.out.println("y : " + getY() + " other.y + other.height - 2 : " + (other.getY() + other.getHeight() - 2)); if (getX()+getWidth()>other.getX()+2){ setHorizontalDirection(Direction.DIRECTION_RIGHT); } else if (getX()<(other.getX()+other.getWidth()-2)){ setHorizontalDirection(Direction.DIRECTION_LEFT); } if (getY()+getHeight()>other.getY()+2){ setVerticalDirection(Direction.DIRECTION_UP); } else if (getY()<(other.getY()+other.getHeight()-2)){ setVerticalDirection(Direction.DIRECTION_DOWN); } } EDIT: Solved now. See the changed method in my answer.

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  • 2D game - Missile shooting problem on Android

    - by Niksa
    Hello, I have to make a tank that sits still but moves his turret and shoots missiles. As this is my first Android application ever and I haven't done any game development either, I've come across a few problems... Now, I did the tank and the moving turret once I read the Android tutorial for the LunarLander sample code. So this code is based on the LunarLander code. But I'm having trouble doing the missile firing then SPACE button is being pressed. private void doDraw(Canvas canvas) { canvas.drawBitmap(backgroundImage, 0, 0, null); // draws the tank canvas.drawBitmap(tank, x_tank, y_tank, new Paint()); // draws and rotates the tank turret canvas.rotate((float) mHeading, (float) x_turret + mTurretWidth, y_turret); canvas.drawBitmap(turret, x_turret, y_turret, new Paint()); // draws the grenade that is a regular circle from ShapeDrawable class bullet.setBounds(x_bullet, y_bullet, x_bullet + width, y_bullet + height); bullet.draw(canvas); } UPDATE GAME method private void updateGame() throws InterruptedException { long now = System.currentTimeMillis(); if (mLastTime > now) return; double elapsed = (now - mLastTime) / 1000.0; mLastTime = now; // dUP and dDown, rotates the turret from 0 to 75 degrees. if (dUp) mHeading += 1 * (PHYS_SLEW_SEC * elapsed); if (mHeading >= 75) mHeading = 75; if (dDown) mHeading += (-1) * (PHYS_SLEW_SEC * elapsed); if (mHeading < 0) mHeading = 0; if (dSpace){ // missile Logic, a straight trajectorie for now x_bullet -= 1; y_bullet -= 1; //doesn't work, has to be updated every pixel or what? } boolean doKeyDown(int keyCode, KeyEvent msg) { boolean handled = false; synchronized (mSurfaceHolder) { if (keyCode == KeyEvent.KEYCODE_SPACE){ dSpace = true; handled = true; } if (keyCode == KeyEvent.KEYCODE_DPAD_UP){ dUp = true; handled = true; } if (keyCode == KeyEvent.KEYCODE_DPAD_DOWN){ dDown = true; handled = true; } return handled; } } } a method run that runs the game... public void run() { while (mRun) { Canvas c = null; try { c = mSurfaceHolder.lockCanvas(null); synchronized (mSurfaceHolder) { if (mMode == STATE_RUNNING) updateGame(); doDraw(c); } } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } finally { // do this in a finally so that if an exception is thrown // during the above, we don't leave the Surface in an // inconsistent state if (c != null) { mSurfaceHolder.unlockCanvasAndPost(c); } } } } So the question would be, how do I make that the bullet is fired on a single SPACE key press from the turret to the end of the screen? Could you help me out here, I seem to be in the dark here... Thanks, Niksa

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  • How do you handle objects that need custom behavior, and need to exist as an entity in the database?

    - by Scott Whitlock
    For a simple example, assume your application sends out notifications to users when various events happen. So in the database I might have the following tables: TABLE Event EventId uniqueidentifier EventName varchar TABLE User UserId uniqueidentifier Name varchar TABLE EventSubscription EventUserId EventId UserId The events themselves are generated by the program. So there are hard-coded points in the application where an event instance is generated, and it needs to notify all the subscribed users. So, the application itself doesn't edit the Event table, except during initial installation, and during an update where a new Event might be created. At some point, when an event is generated, the application needs to lookup the Event and get a list of Users. What's the best way to link the event in the source code to the event in the database? Option 1: Store the EventName in the program as a fixed constant, and look it up by name. Option 2: Store the EventId in the program as a static Guid, and look it up by ID. Extra Credit In other similar circumstances I may want to include custom behavior with the event type. That is, I'll want subclasses of my Event entity class with different behaviors, and when I lookup an event, I want it to return an instance of my subclass. For instance: class Event { public Guid Id { get; } public Guid EventName { get; } public ReadOnlyCollection<EventSubscription> EventSubscriptions { get; } public void NotifySubscribers() { foreach(var eventSubscription in EventSubscriptions) { eventSubscription.Notify(); } this.OnSubscribersNotified(); } public virtual void OnSubscribersNotified() {} } class WakingEvent : Event { private readonly IWaker waker; public WakingEvent(IWaker waker) { if(waker == null) throw new ArgumentNullException("waker"); this.waker = waker; } public override void OnSubscribersNotified() { this.waker.Wake(); base.OnSubscribersNotified(); } } So, that means I need to map WakingEvent to whatever key I'm using to look it up in the database. Let's say that's the EventId. Where do I store this relationship? Does it go in the event repository class? Should the WakingEvent know declare its own ID in a static member or method? ...and then, is this all backwards? If all events have a subclass, then instead of retrieving events by ID, should I be asking my repository for the WakingEvent like this: public T GetEvent<T>() where T : Event { ... // what goes here? ... } I can't be the first one to tackle this. What's the best practice?

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  • where to define variable for a for each loop?

    - by David
    can you please advise me why my first code attempt didn't work : public void listAllFiles() { for(String filename : files) { int position = 0; System.out.println(position + ": " + filename); position = position + 1; } } it kept printing position at 0 without iterating position but it seems to work after i did it this way: public void listAllFiles() { int position = 0; for(String filename : files) { System.out.println(position + ": " + filename); position = position + 1; } } I don't understand why the position + 1 was not being executed, is it because we are not meant to define variables inside for loops or am i missing something in my code.

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  • Functions returning pointers

    - by fg nu
    C++ noob here. I have a very basic question about a construct I found in the C++ book I am reading. // class declaration class CStr { char sData[256]; public: char* get(void); }; // implementation of the function char* CStr::get(void) { return sData; } So the Cstr::get function is obviously meant to return a character pointer, but the function is passing what looks like the value (return sData). Does C++ know to return the address of the returned object? My guess would have been that the function definition would be return &sData.

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  • Mutable Records in F#

    - by MarkPearl
    I’m loving my expert F# book – today I thought I would give a post on using mutable records as covered in Chapter 4 of Expert F#. So as they explain the simplest mutable data structures in F# are mutable records. The whole concept of things by default being immutable is a new one for me from my C# background. Anyhow… lets look at some C# code first. using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace MutableRecords { public class DiscreteEventCounter { public int Total { get; set; } public int Positive { get; set; } public string Name { get; private set; } public DiscreteEventCounter(string name) { Name = name; } } class Program { private static void recordEvent(DiscreteEventCounter s, bool isPositive) { s.Total += 1; if (isPositive) s.Positive += 1; } private static void reportStatus (DiscreteEventCounter s) { Console.WriteLine("We have {0} {1} out of {2}", s.Positive, s.Name, s.Total); } static void Main(string[] args) { var longCounter = new DiscreteEventCounter("My Discrete Counter"); recordEvent(longCounter, true); recordEvent(longCounter, true); reportStatus(longCounter); Console.ReadLine(); } } } Quite simple, we have a class that has a few values. We instantiate an instance of the class and perform increments etc on the instance. Now lets look at an equivalent F# sample. namespace EncapsulationNS module Module1 = open System type DiscreteEventCounter = { mutable Total : int mutable Positive : int Name : string } let recordEvent (s: DiscreteEventCounter) isPositive = s.Total <- s.Total+1 if isPositive then s.Positive <- s.Positive+1 let reportStatus (s: DiscreteEventCounter) = printfn "We have %d %s out of %d" s.Positive s.Name s.Total let newCounter nm = { Total = 0; Positive = 0; Name = nm } // // Using it... // let longCounter = newCounter "My Discrete Counter" recordEvent longCounter (true) recordEvent longCounter (true) reportStatus longCounter System.Console.ReadLine() Notice in the type declaration of the DiscreteEventCounter we had to explicitly declare that the total and positive value holders were mutable. And that’s it – a very simple example of mutable types.

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  • Undeclared Scope in Rock Paper Scissors Simple Game

    - by Rianelle
    #include <iostream> #include <string> #include <cstdlib> #include <ctime> using namespace std; bool win; int winnings; int draws; int loses; string comChoice; string playerChoice; void winGame () { cout << "You won! Play again?" <<endl; cout << "Type y/n" <<endl; char x; cin >> x; if (x == 'y') { beginGame(); } else if ('n'){ cout << "Game Stopped." <<endl; cout << "Number of Draws: " <<draws << endl; cout << "Number of Loses: " <<loses << endl; cout << "Number of Wins: " << winnings << endl; win = true; } } void drawGame (){ ++draws; cout << "Draw! Try again" << endl; return; } void lose () { cout << "You lose! Try again?" <<endl; cout << "Type y/n" <<endl; char feedback; cin >> feedback; if (feedback == 'y') { beginGame(); } else if ('n'){ cout << "Game Stopped." <<endl; cout << "Number of Draws: " <<draws << endl; cout << "Number of Loses: " <<loses << endl; cout << "Number of Wins: " << winnings << endl; } } void beginGame() { cout << "Welcome to the Rock, Paper and Scissors Game!" <<endl; cout << "Let's begin. Type <rock, paper, scissors> for your choice!" <<endl; cin >> playerChoice; srand(time(0)); int randomizer = 1+(rand()%3); if (randomizer == 1) comChoice = "rock"; if (randomizer == 2) comChoice = "paper"; if (randomizer == 3) comChoice = "scissors"; do { if (playerChoice == comChoice) { drawGame(); } if (playerChoice == "rock" && comChoice == "paper") ++loses; lose(); if (playerChoice == "rock" && comChoice == "scissors") ++winnings; winGame(); if (playerChoice == "paper" && comChoice == "rock") ++winnings; winGame(); if (playerChoice == "paper" && comChoice == "scissors") ++loses; lose(); if (playerChoice == "scissors" && comChoice == "rock") ++loses; lose(); if (playerChoice == "scissors" && comChoice == "paper") ++winnings; winGame(); }while (win != true); } int main () { beginGame(); return 0; }

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  • Of which bad practice is require calling functions in order a sign?

    - by stijn
    Sometimes I find myself writing comments on class methods like this: class A : public Base { public: /** * Sets variable; * should be called before ImplementsInterfaceMtehod(), * else has no effect. */ void SetSomeVariable( var_type value ); virtual void ImplementsInterfaceMethod(); } The callers of Base::ImplementsInterfaceMethod obviously do not know about the variable, and should not. But the users of A should set the variable if they want it to take effect. It is not required to set the variable (else it could be a parameter for the constructor), so I cannot throw exceptions in ImplementsInterfaceMethod if it is not set. Is this a sign of some typical bad practice? Is there a better way than writing a comment as shown to deal with this?

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  • Bullet Physics implementing custom MotionState class

    - by Arosboro
    I'm trying to make my engine's camera a kinematic rigid body that can collide into other rigid bodies. I've overridden the btMotionState class and implemented setKinematicPos which updates the motion state's tranform. I use the overridden class when creating my kinematic body, but the collision detection fails. I'm doing this for fun trying to add collision detection and physics to Sean O' Neil's Procedural Universe I referred to the bullet wiki on MotionStates for my CPhysicsMotionState class. If it helps I can add the code for the Planetary rigid bodies, but I didn't want to clutter the post. Here is my motion state class: class CPhysicsMotionState: public btMotionState { protected: // This is the transform with position and rotation of the camera CSRTTransform* m_srtTransform; btTransform m_btPos1; public: CPhysicsMotionState(const btTransform &initialpos, CSRTTransform* srtTransform) { m_srtTransform = srtTransform; m_btPos1 = initialpos; } virtual ~CPhysicsMotionState() { // TODO Auto-generated destructor stub } virtual void getWorldTransform(btTransform &worldTrans) const { worldTrans = m_btPos1; } void setKinematicPos(btQuaternion &rot, btVector3 &pos) { m_btPos1.setRotation(rot); m_btPos1.setOrigin(pos); } virtual void setWorldTransform(const btTransform &worldTrans) { btQuaternion rot = worldTrans.getRotation(); btVector3 pos = worldTrans.getOrigin(); m_srtTransform->m_qRotate = CQuaternion(rot.x(), rot.y(), rot.z(), rot.w()); m_srtTransform->SetPosition(CVector(pos.x(), pos.y(), pos.z())); m_btPos1 = worldTrans; } }; I add a rigid body for the camera: // Create rigid body for camera btCollisionShape* cameraShape = new btSphereShape(btScalar(5.0f)); btTransform startTransform; startTransform.setIdentity(); // forgot to add this line CVector vCamera = m_srtCamera.GetPosition(); startTransform.setOrigin(btVector3(vCamera.x, vCamera.y, vCamera.z)); m_msCamera = new CPhysicsMotionState(startTransform, &m_srtCamera); btScalar tMass(80.7f); bool isDynamic = (tMass != 0.f); btVector3 localInertia(0,0,0); if (isDynamic) cameraShape->calculateLocalInertia(tMass,localInertia); btRigidBody::btRigidBodyConstructionInfo rbInfo(tMass, m_msCamera, cameraShape, localInertia); m_rigidBody = new btRigidBody(rbInfo); m_rigidBody->setCollisionFlags(m_rigidBody->getCollisionFlags() | btCollisionObject::CF_KINEMATIC_OBJECT); m_rigidBody->setActivationState(DISABLE_DEACTIVATION); This is the code in Update() that runs each frame: CSRTTransform srtCamera = CCameraTask::GetPtr()->GetCamera(); Quaternion qRotate = srtCamera.m_qRotate; btQuaternion rot = btQuaternion(qRotate.x, qRotate.y, qRotate.z, qRotate.w); CVector vCamera = CCameraTask::GetPtr()->GetPosition(); btVector3 pos = btVector3(vCamera.x, vCamera.y, vCamera.z); CPhysicsMotionState* cameraMotionState = CCameraTask::GetPtr()->GetMotionState(); cameraMotionState->setKinematicPos(rot, pos);

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  • Can a language support something like "Retry/Fix"?

    - by Aaron Anodide
    I was just wondering if a language could support something like a Retry/Fix block? The answer to this question is probably the reason it's a bad idea or equivalent to something else, but the idea keeps popping into my head. void F() { try { G(); } fix(WrongNumber wn, out int x) { x = 1; } } void G() { int x = 0; retry<int> { if(x != 1) throw new WrongNumber(x); } } After the fix block ran, the retry block would run again...

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  • how to fix fatal error jvmti.h No such file or directory compilation terminated on c code ubuntu? [on hold]

    - by Blue Rose
    how to fix fatal error jvmti.h No such file or directory compilation terminated c code ubuntu? my c code is: #include "jvmti.h" JNIEXPORT jint JNICALL Agent_OnLoad(JavaVM *jvm, char *options, void *reserved) { /* We return JNI_OK to signify success */ printf("\nBushra Za'areer,\n\n"); return JNI_OK; } JNIEXPORT void JNICALL Agent_OnUnload(JavaVM *vm) { } type this command in terminal: gcc -Wall -W -Werror first_agent.c -o firstagent first_agent.c:1:19: fatal error: jvmti.h: No such file or directory compilation terminated. where java jdk version javac 1.7.0_25 where gcc version gcc version 4.7.3 (Ubuntu/Linaro 4.7.3-2ubuntu4) here should update gcc version to 4.8?

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  • What is upcasting/downcasting?

    - by acidzombie24
    When learning about polymorphism you commonly see something like this class Base { int prv_member; virtual void fn(){} } class Derived : Base { int more_data; virtual void fn(){} } What is upcasting or downcasting? Is (Derived*)base_ptr; an upcast or downcast? I call it upcast because you are going away from the base into something more specific. Other people told me it is a downcast because you are going down a hierarchy into something specific with the top being the root. But other people seem to call it what i call it. When converting a base ptr to a derived ptr is it called upcasting or downcasting? and if someone can link to an official source or explain why its called that than great.

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  • Cocos2d: Adding a CCSequence to a CCArray

    - by Axort
    I have a problem with an action performed by a sprite. I have one CCSequence in a CCArray and I have an scheduled method (is called every 5 seconds) that make the sprite run the action. The action is performed correctly only the first time (the first 5 seconds), after that, the action do whatever it wants lol. Here is the code: In .h - @interface PowerUpLayer : CCLayer { PowerUp *powerUp; CCArray *trajectories; } @property (nonatomic, retain) CCArray *trajectories; In .mm - @implementation PowerUpLayer @synthesize trajectories; -(id)init { if((self = [super init])) { [self createTrajectories]; self.isTouchEnabled = YES; [self schedule:@selector(spawn:) interval:5]; } return self; } -(void)createTrajectories { self.trajectories = [CCArray arrayWithCapacity:1]; //Wave trajectory ccBezierConfig firstWave, secondWave; firstWave.controlPoint_1 = CGPointMake([[CCDirector sharedDirector] winSize].width + 30, [[CCDirector sharedDirector] winSize].height / 2);//powerUp.sprite.position.x, powerUp.sprite.position.y); firstWave.controlPoint_2 = CGPointMake([[CCDirector sharedDirector] winSize].width - ([[CCDirector sharedDirector] winSize].width / 4), 0); firstWave.endPosition = CGPointMake([[CCDirector sharedDirector] winSize].width / 2, [[CCDirector sharedDirector] winSize].height / 2); secondWave.controlPoint_1 = CGPointMake([[CCDirector sharedDirector] winSize].width / 2, [[CCDirector sharedDirector] winSize].height / 2); secondWave.controlPoint_2 = CGPointMake([[CCDirector sharedDirector] winSize].width / 4, [[CCDirector sharedDirector] winSize].height); secondWave.endPosition = CGPointMake(-30, [[CCDirector sharedDirector] winSize].height / 2); id bezierWave1 = [CCBezierTo actionWithDuration:1 bezier:firstWave]; id bezierWave2 = [CCBezierTo actionWithDuration:1 bezier:secondWave]; id waveTrajectory = [CCSequence actions:bezierWave1, bezierWave2, [CCCallFuncN actionWithTarget:self selector:@selector(setInvisible:)], nil]; [self.trajectories addObject:waveTrajectory]; //[powerUp.sprite runAction:bezierForward]; // [CCMoveBy actionWithDuration:3 position:CGPointMake(-[[CCDirector sharedDirector] winSize].width - powerUp.sprite.contentSize.width, 0)] //[powerUp.sprite runAction:[CCSequence actions:bezierWave1, bezierWave2, [CCCallFuncN actionWithTarget:self selector:@selector(setInvisible:)], nil]]; } -(void)setInvisible:(id)sender { if(powerUp != nil) { [self removeChild:sender cleanup:YES]; powerUp = nil; } } This is the scheduled method: -(void)spawn:(ccTime)dt { if(powerUp == nil) { powerUp = [[PowerUp alloc] initWithType:0]; powerUp.sprite.position = CGPointMake([[CCDirector sharedDirector] winSize].width + powerUp.sprite.contentSize.width, [[CCDirector sharedDirector] winSize].height / 2); [self addChild:powerUp.sprite z:-1]; [powerUp.sprite runAction:((CCSequence *)[self.trajectories objectAtIndex:0])]; } } I don't know what is happening; I never modify the content of the CCSequence after the first time. Thanks!

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  • Draw Bug 2D player Camera

    - by RedShft
    I have just implemented a 2D player camera for my game, everything works properly except the player on the screen jitters when it moves between tiles. What I mean by jitter, is that if the player is moving the camera updates the tileset to be drawn and if the player steps to the right, the camera snaps that way. The movement is not smooth. I'm guessing this is occurring because of how I implemented the function to calculate the current viewable area or how my draw function works. I'm not entirely sure how to fix this. This camera system was entirely of my own creation and a first attempt at that, so it's very possible this is not a great way of doing things. My camera class, pulls information from the current tileset and calculates the viewable area. Right now I am targettng a resolution of 800 by 600. So I try to fit the appropriate amount of tiles for that resolution. My camera class, after calculating the current viewable tileset relative to the players location, returns a slice of the original tileset to be drawn. This tileset slice is updated every frame according to the players position. This slice is then passed to the map class, which draws the tile on screen. //Map Draw Function //This draw function currently matches the GID of the tile to it's location on the //PNG file of the tileset and then draws this portion on the screen void Draw(SDL_Surface* background, int[] _tileSet) { enforce( tilesetImage != null, "Tileset is null!"); enforce( background != null, "BackGround is null!"); int i = 0; int j = 0; SDL_Rect DestR, SrcR; SrcR.x = 0; SrcR.y = 0; SrcR.h = 32; SrcR.w = 32; foreach(tile; _tileSet) { //This code is matching the current tiles ID to the tileset image SrcR.x = cast(short)(tileWidth * (tile >= 11 ? (tile - ((tile / 10) * 10) - 1) : tile - 1)); SrcR.y = cast(short)(tileHeight * (tile > 10 ? (tile / 10) : 0)); //Applying the tile to the surface SDL_BlitSurface( tilesetImage, &SrcR, background, &DestR ); //this keeps track of what column/row we are on i++; if ( i == mapWidth ) { i = 0; j++; } DestR.x = cast(short)(i * tileWidth); DestR.y = cast(short)(j * tileHeight); } } //Camera Class class Camera { private: //A rectangle representing the view area SDL_Rect viewArea; //In number of tiles int viewAreaWidth; int viewAreaHeight; //This is the x and y coordinate of the camera in MAP SPACE IN PIXELS vect2 cameraCoordinates; //The player location in map space IN PIXELS vect2 playerLocation; //This is the players location in screen space; vect2 playerScreenLoc; int playerTileCol; int playerTileRow; int cameraTileCol; int cameraTileRow; //The map is stored in a single array with the tile ids //this corresponds to the index of the starting and ending tile int cameraStartTile, cameraEndTile; //This is a slice of the current tile set int[] tileSetCopy; int mapWidth; int mapHeight; int tileWidth; int tileHeight; public: this() { this.viewAreaWidth = 25; this.viewAreaHeight = 19; this.cameraCoordinates = vect2(0, 0); this.playerLocation = vect2(0, 0); this.viewArea = SDL_Rect (0, 0, 0, 0); this.tileWidth = 32; this.tileHeight = 32; } void Init(vect2 playerPosition, ref int[] tileSet, int mapWidth, int mapHeight ) { playerLocation = playerPosition; this.mapWidth = mapWidth; this.mapHeight = mapHeight; CalculateCurrentCameraPosition( tileSet, playerPosition ); //writeln( "Tile Set Copy: ", tileSetCopy ); //writeln( "Orginal Tile Set: ", tileSet ); } void CalculateCurrentCameraPosition( ref int[] tileSet, vect2 playerPosition ) { playerLocation = playerPosition; playerTileCol = cast(int)((playerLocation.x / tileWidth) + 1); playerTileRow = cast(int)((playerLocation.y / tileHeight) + 1); //writeln( "Player Tile (Column, Row): ","(", playerTileCol, ", ", playerTileRow, ")"); cameraTileCol = playerTileCol - (viewAreaWidth / 2); cameraTileRow = playerTileRow - (viewAreaHeight / 2); CameraMapBoundsCheck(); //writeln( "Camera Tile Start (Column, Row): ","(", cameraTileCol, ", ", cameraTileRow, ")"); cameraStartTile = ( (cameraTileRow - 1) * mapWidth ) + cameraTileCol - 1; //writeln( "Camera Start Tile: ", cameraStartTile ); cameraEndTile = cameraStartTile + ( viewAreaWidth * viewAreaHeight ) * 2; //writeln( "Camera End Tile: ", cameraEndTile ); tileSetCopy = tileSet[cameraStartTile..cameraEndTile]; } vect2 CalculatePlayerScreenLocation() { cameraCoordinates.x = cast(float)(cameraTileCol * tileWidth); cameraCoordinates.y = cast(float)(cameraTileRow * tileHeight); playerScreenLoc = playerLocation - cameraCoordinates + vect2(32, 32);; //writeln( "Camera Coordinates: ", cameraCoordinates ); //writeln( "Player Location (Map Space): ", playerLocation ); //writeln( "Player Location (Screen Space): ", playerScreenLoc ); return playerScreenLoc; } void CameraMapBoundsCheck() { if( cameraTileCol < 1 ) cameraTileCol = 1; if( cameraTileRow < 1 ) cameraTileRow = 1; if( cameraTileCol + 24 > mapWidth ) cameraTileCol = mapWidth - 24; if( cameraTileRow + 19 > mapHeight ) cameraTileRow = mapHeight - 19; } ref int[] GetTileSet() { return tileSetCopy; } int GetViewWidth() { return viewAreaWidth; } }

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  • touch in guiTexture

    - by Mitananda
    Before time in my game start. i want there will show a guiTexture.. if i touch this guiTexture, that will hidden and the time game will start. I try to make a script but it doesn't work. I'm a bit confused by the Unity documentation. please help me i'm newbie in Unity. my code : void Start () { if (myGuiTexture.HitTest(Input.GetTouch(0).position)) { if (Input.GetTouch(0).phase == TouchPhase.Began) { Time.timeScale = 1; myGuiTexture.enable = false; } } } and i also create this source but its doesn't work too. void Start () { if (tutorial.HitTest(new Vector3(0,0,0))){ Time.timeScale = 1; } }

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  • rotate player based off of joystick

    - by pengume
    Hey everyone I have this game that i am making in android and I have a touch screen joystick that moves the player around based on the joysticks position. I cant figure out how to also get the player to rotate at the same angle of the joystick. so when the joystick is to the left the players bitmap is rotated to the left as well. Maybe someone here has some sample code I could look at here is the joysticks class that I am using. `public class GameControls implements OnTouchListener { public float initx = DroidzActivity.screenWidth - 45; //255; // 320 og 425 public float inity = DroidzActivity.screenHeight - 45;//425; // 480 og 267 public Point _touchingPoint = new Point( DroidzActivity.screenWidth - 45, DroidzActivity.screenHeight - 45); public Point _pointerPosition = new Point(DroidzActivity.screenWidth - 100, DroidzActivity.screenHeight - 100); // ogx 220 ogy 150 private Boolean _dragging = false; private boolean attackMode = false; @Override public boolean onTouch(View v, MotionEvent event) { update(event); return true; } private MotionEvent lastEvent; public boolean ControlDragged; private static double angle; public void update(MotionEvent event) { if (event == null && lastEvent == null) { return; } else if (event == null && lastEvent != null) { event = lastEvent; } else { lastEvent = event; } // drag drop if (event.getAction() == MotionEvent.ACTION_DOWN) { if ((int) event.getX() > 0 && (int) event.getX() < 50 && (int) event.getY() > DroidzActivity.screenHeight - 160 && (int) event.getY() < DroidzActivity.screenHeight - 0) { setAttackMode(true); } else { _dragging = true; } } else if (event.getAction() == MotionEvent.ACTION_UP) { if(isAttackMode()){ setAttackMode(false); } _dragging = false; } if (_dragging) { ControlDragged = true; // get the pos _touchingPoint.x = (int) event.getX(); _touchingPoint.y = (int) event.getY(); // Log.d("GameControls", "x = " + _touchingPoint.x + " y = " //+ _touchingPoint.y); // bound to a box if (_touchingPoint.x < DroidzActivity.screenWidth - 75) { // og 400 _touchingPoint.x = DroidzActivity.screenWidth - 75; } if (_touchingPoint.x > DroidzActivity.screenWidth - 15) {// og 450 _touchingPoint.x = DroidzActivity.screenWidth - 15; } if (_touchingPoint.y < DroidzActivity.screenHeight - 75) {// og 240 _touchingPoint.y = DroidzActivity.screenHeight - 75; } if (_touchingPoint.y > DroidzActivity.screenHeight - 15) {// og 290 _touchingPoint.y = DroidzActivity.screenHeight - 15; } // get the angle setAngle(Math.atan2(_touchingPoint.y - inity, _touchingPoint.x - initx) / (Math.PI / 180)); // Move the ninja in proportion to how far // the joystick is dragged from its center _pointerPosition.y += Math.sin(getAngle() * (Math.PI / 180)) * (_touchingPoint.x / 70); // og 180 70 _pointerPosition.x += Math.cos(getAngle() * (Math.PI / 180)) * (_touchingPoint.x / 70); // make the pointer go thru if (_pointerPosition.x > DroidzActivity.screenWidth) { _pointerPosition.x = 0; } if (_pointerPosition.x < 0) { _pointerPosition.x = DroidzActivity.screenWidth; } if (_pointerPosition.y > DroidzActivity.screenHeight) { _pointerPosition.y = 0; } if (_pointerPosition.y < 0) { _pointerPosition.y = DroidzActivity.screenHeight; } } else if (!_dragging) { ControlDragged = false; // Snap back to center when the joystick is released _touchingPoint.x = (int) initx; _touchingPoint.y = (int) inity; // shaft.alpha = 0; } } public void setAttackMode(boolean attackMode) { this.attackMode = attackMode; } public boolean isAttackMode() { return attackMode; } public void setAngle(double angle) { this.angle = angle; } public static double getAngle() { return angle; } }` I should also note that the player has animations based on when he is moving or attacking. EDIT: I got the angle and am rotating the sprite around in the correct angle however it rotates on the wrong spot. My sprite is one giant bitmap that gets cut into four pieces and only one shown at a time to animate walking. here is the code I am using to rotate him right now. ` public void draw(Canvas canvas,int pointerX, int pointerY) { Matrix m; if (setRotation){ // canvas.save(); m = new Matrix(); m.reset(); // spriteWidth and spriteHeight are for just the current frame showed //m.setTranslate(spriteWidth / 2, spriteHeight / 2); //get and set rotation for ninja based off of joystick m.preRotate((float) GameControls.getRotation()); //create the rotated bitmap flipedSprite = Bitmap.createBitmap(bitmap , 0, 0,bitmap.getWidth(),bitmap.getHeight() , m, true); //set new bitmap to rotated ninja setBitmap(flipedSprite); setRotation = false; // canvas.restore(); Log.d("Ninja View", "angle of rotation= " +(float) GameControls.getRotation()); } ` And then the draw method // create the destination rectangle for the ninjas current animation frame // pointerX and pointerY are from the joystick moving the ninja around destRect = new Rect(pointerX, pointerY, pointerX + spriteWidth, pointerY + spriteHeight); canvas.drawBitmap(bitmap, getSourceRect(), destRect, null);

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  • Would you want a language to support something like "Retry/Fix"?

    - by Aaron Anodide
    I was just wondering if a language could support something like a Retry/Fix block? The answer to this question is probably the reason it's a bad idea or equivalent to something else, but the idea keeps popping into my head. void F() { try { G(); } fix(WrongNumber wn, out int x) { x = 1; } } void G() { int x = 0; retry<int> { if(x != 1) throw new WrongNumber(x); } } After the fix block ran, the retry block would run again...

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  • Navigation in a #WP7 application with MVVM Light

    - by Laurent Bugnion
    In MVVM applications, it can be a bit of a challenge to send instructions to the view (for example a page) from a viewmodel. Thankfully, we have good tools at our disposal to help with that. In his excellent series “MVVM Light Toolkit soup to nuts”, Jesse Liberty proposes one approach using the MVVM Light messaging infrastructure. While this works fine, I would like to show here another approach using what I call a “view service”, i.e. an abstracted service that is invoked from the viewmodel, and implemented on the view. Multiple kinds of view services In fact, I use view services quite often, and even started standardizing them for the Windows Phone 7 applications I work on. If there is interest, I will be happy to show other such view services, for example Animation services, responsible to start/stop animations on the view. Dialog service, in charge of displaying messages to the user and gathering feedback. Navigation service, in charge of navigating to a given page directly from the viewmodel. In this article, I will concentrate on the navigation service. The INavigationService interface In most WP7 apps, the navigation service is used in quite a straightforward way. We want to: Navigate to a given URI. Go back. Be notified when a navigation is taking place, and be able to cancel. The INavigationService interface is quite simple indeed: public interface INavigationService { event NavigatingCancelEventHandler Navigating; void NavigateTo(Uri pageUri); void GoBack(); } Obviously, this interface can be extended if necessary, but in most of the apps I worked on, I found that this covers my needs. The NavigationService class It is possible to nicely pack the navigation service into its own class. To do this, we need to remember that all the PhoneApplicationPage instances use the same instance of the navigation service, exposed through their NavigationService property. In fact, in a WP7 application, it is the main frame (RootFrame, of type PhoneApplicationFrame) that is responsible for this task. So, our implementation of the NavigationService class can leverage this. First the class will grab the PhoneApplicationFrame and store a reference to it. Also, it registers a handler for the Navigating event, and forwards the event to the listening viewmodels (if any). Then, the NavigateTo and the GoBack methods are implemented. They are quite simple, because they are in fact just a gateway to the PhoneApplicationFrame. The whole class is as follows: public class NavigationService : INavigationService { private PhoneApplicationFrame _mainFrame; public event NavigatingCancelEventHandler Navigating; public void NavigateTo(Uri pageUri) { if (EnsureMainFrame()) { _mainFrame.Navigate(pageUri); } } public void GoBack() { if (EnsureMainFrame() && _mainFrame.CanGoBack) { _mainFrame.GoBack(); } } private bool EnsureMainFrame() { if (_mainFrame != null) { return true; } _mainFrame = Application.Current.RootVisual as PhoneApplicationFrame; if (_mainFrame != null) { // Could be null if the app runs inside a design tool _mainFrame.Navigating += (s, e) => { if (Navigating != null) { Navigating(s, e); } }; return true; } return false; } } Exposing URIs I find that it is a good practice to expose each page’s URI as a constant. In MVVM Light applications, a good place to do that is the ViewModelLocator, which already acts like a central point of setup for the views and their viewmodels. Note that in some cases, it is necessary to expose the URL as a string, for instance when a query string needs to be passed to the view. So for example we could have: public static readonly Uri MainPageUri = new Uri("/MainPage.xaml", UriKind.Relative); public const string AnotherPageUrl = "/AnotherPage.xaml?param1={0}&param2={1}"; Creating and using the NavigationService Normally, we only need one instance of the NavigationService class. In cases where you use an IOC container, it is easy to simply register a singleton instance. For example, I am using a modified version of a super simple IOC container, and so I can register the navigation service as follows: SimpleIoc.Register<INavigationService, NavigationService>(); Then, it can be resolved where needed with: SimpleIoc.Resolve<INavigationService>(); Or (more frequently), I simply declare a parameter on the viewmodel constructor of type INavigationService and let the IOC container do its magic and inject the instance of the NavigationService when the viewmodel is created. On supported platforms (for example Silverlight 4), it is also possible to use MEF. Or, of course, we can simply instantiate the NavigationService in the ViewModelLocator, and pass this instance as a parameter of the viewmodels’ constructor, injected as a property, etc… Once the instance has been passed to the viewmodel, it can be used, for example with: NavigationService.NavigateTo(ViewModelLocator.ComparisonPageUri); Testing Thanks to the INavigationService interface, navigation can be mocked and tested when the viewmodel is put under unit test. Simply implement and inject a mock class, and assert that the methods are called as they should by the viewmodel. Conclusion As usual, there are multiple ways to code a solution answering your needs. I find that view services are a really neat way to delegate view-specific responsibilities such as animation, dialogs and of course navigation to other classes through an abstracted interface. In some cases, such as the NavigationService class exposed here, it is even possible to standardize the implementation and pack it in a class library for reuse. I hope that this sample is useful! Happy coding. Laurent   Laurent Bugnion (GalaSoft) Subscribe | Twitter | Facebook | Flickr | LinkedIn

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  • Setting a leader from a sprite array

    - by Craig
    I'm looking to set a leader from an array of sprites, I keep on getting a NullReferenceException was unhandled error from within my main game class when calling the UpdateMouse Method. What have I dont wrong here? class MouseSprite { Random random = new Random(); private MouseSprite leader; public void UpdateBoundaryBox() { mouseBounds.X = (int)mousePosition.X - mouseTexture.Width / 2; mouseBounds.Y = (int)mousePosition.Y - mouseTexture.Height / 2; } public void UpdateMouse(Vector2 position, MouseSprite [] mice, int numberMice, int index) { Vector2 catPosition = position; int enemies = numberMice; this.alive = true; mice[random.Next(0, mice.Length)] = leader;

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  • Why my collision detection is not accurate?

    - by optimisez
    After trying and trying, I still cannot understand why the leg of character exceeds the wall but no clipping issue when I hit the wall from below. How should I fix it to make him standstill on the wall? void initPlayer() { // Create texture. hr = D3DXCreateTextureFromFileEx(d3dDevice, "player.png", 169, 44, D3DX_DEFAULT, NULL, D3DFMT_A8R8G8B8, D3DPOOL_MANAGED, D3DX_DEFAULT, D3DX_DEFAULT, D3DCOLOR_XRGB(255, 255, 255), NULL, NULL, &player); playerRect.left = playerRect.top = 0; playerRect.right = 29; playerRect.bottom = 36; playerDest.X = 0; playerDest.Y = 564; playerDest.length = playerRect.right - playerRect.left; playerDest.height = playerRect.bottom - playerRect.top; } void initBox() { hr = D3DXCreateTextureFromFileEx(d3dDevice, "brock.png", 330, 132, D3DX_DEFAULT, NULL, D3DFMT_A8R8G8B8, D3DPOOL_MANAGED, D3DX_DEFAULT, D3DX_DEFAULT, D3DCOLOR_XRGB(255, 255, 255), NULL, NULL, &box); boxRect.left = 33; boxRect.top = 0; boxRect.right = 63; boxRect.bottom = 30; boxDest.X = boxDest.Y = 300; boxDest.length = boxRect.right - boxRect.left; boxDest.height = boxRect.bottom - boxRect.top; } bool spriteCollide(Entity player, Entity target) { float left1, left2; float right1, right2; float top1, top2; float bottom1, bottom2; left1 = player.X; left2 = target.X; right1 = player.X + player.length; right2 = target.X + target.length; top1 = player.Y; top2 = target.Y; bottom1 = player.Y + player.height; bottom2 = target.Y + target.height; if (bottom1 < top2) return false; if (top1 > bottom2) return false; if (right1 < left2) return false; if (left1 > right2) return false; return true; } void collideWithBox() { if ( spriteCollide(playerDest, boxDest) && keyArr[VK_UP]) //playerDest.Y += 50; playerDest.Y = boxDest.Y + boxDest.height; else if ( spriteCollide(playerDest, boxDest) && !keyArr[VK_UP]) playerDest.Y = boxDest.Y - boxDest.height; }

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