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  • Camera wont stay behind model after pitch, then rotation

    - by ChocoMan
    I have a camera position behind a model. Currently, if I push the left thumbstick making my model move forward, backward, or strafe, the camera stays with the model. If I push the right thumbstick left or right, the model rotates in those directions fine along with the camera rotating while maintaining its position relatively behind the model. But when I pitch the model up or down, then rotate the model afterwards, the camera moves slightly rotates in a clock-like fashion behind the model. If I do a few rotations of the model and try to pitch the camera, the camera will eventually be looking at the side, then eventually the front of the model while also rotating in a clock-like fashion. My question is, how do I keep the camera to pitch up and down behind the model no matter how much the model has rotated? Here is what I got: // Rotates model and pitches camera on its own axis public void modelRotMovement(GamePadState pController) { // Rotates Camera with model Yaw = pController.ThumbSticks.Right.X * MathHelper.ToRadians(angularSpeed); // Pitches Camera around model Pitch = pController.ThumbSticks.Right.Y * MathHelper.ToRadians(angularSpeed); AddRotation = Quaternion.CreateFromYawPitchRoll(Yaw, 0, 0); ModelLoad.MRotation *= AddRotation; MOrientation = Matrix.CreateFromQuaternion(ModelLoad.MRotation); } // Orbit (yaw) Camera around with model (only seeing back of model) public void cameraYaw(Vector3 axisYaw, float yaw) { ModelLoad.CameraPos = Vector3.Transform(ModelLoad.CameraPos - ModelLoad.camTarget, Matrix.CreateFromAxisAngle(axisYaw, yaw)) + ModelLoad.camTarget; } // Raise camera above or below model's shoulders public void cameraPitch(Vector3 axisPitch, float pitch) { ModelLoad.CameraPos = Vector3.Transform(ModelLoad.CameraPos - ModelLoad.camTarget, Matrix.CreateFromAxisAngle(axisPitch, pitch)) + ModelLoad.camTarget; } // Call in update method public void updateCamera() { cameraYaw(Vector3.Up, Yaw); cameraPitch(Vector3.Right, Pitch); } NOTE: I tried to use addPitch just like addRotation but it didn't work...

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  • C#: Handling Notifications: inheritance, events, or delegates?

    - by James Michael Hare
    Often times as developers we have to design a class where we get notification when certain things happen. In older object-oriented code this would often be implemented by overriding methods -- with events, delegates, and interfaces, however, we have far more elegant options. So, when should you use each of these methods and what are their strengths and weaknesses? Now, for the purposes of this article when I say notification, I'm just talking about ways for a class to let a user know that something has occurred. This can be through any programmatic means such as inheritance, events, delegates, etc. So let's build some context. I'm sitting here thinking about a provider neutral messaging layer for the place I work, and I got to the point where I needed to design the message subscriber which will receive messages from the message bus. Basically, what we want is to be able to create a message listener and have it be called whenever a new message arrives. Now, back before the flood we would have done this via inheritance and an abstract class: 1:  2: // using inheritance - omitting argument null checks and halt logic 3: public abstract class MessageListener 4: { 5: private ISubscriber _subscriber; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber) 11: { 12: _subscriber = subscriber; 13: _messageThread = new Thread(MessageLoop); 14: _messageThread.Start(); 15: } 16:  17: // user will override this to process their messages 18: protected abstract void OnMessageReceived(Message msg); 19:  20: // handle the looping in the thread 21: private void MessageLoop() 22: { 23: while(!_isHalted) 24: { 25: // as long as processing, wait 1 second for message 26: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 27: if(msg != null) 28: { 29: OnMessageReceived(msg); 30: } 31: } 32: } 33: ... 34: } It seems so odd to write this kind of code now. Does it feel odd to you? Maybe it's just because I've gotten so used to delegation that I really don't like the feel of this. To me it is akin to saying that if I want to drive my car I need to derive a new instance of it just to put myself in the driver's seat. And yet, unquestionably, five years ago I would have probably written the code as you see above. To me, inheritance is a flawed approach for notifications due to several reasons: Inheritance is one of the HIGHEST forms of coupling. You can't seal the listener class because it depends on sub-classing to work. Because C# does not allow multiple-inheritance, I've spent my one inheritance implementing this class. Every time you need to listen to a bus, you have to derive a class which leads to lots of trivial sub-classes. The act of consuming a message should be a separate responsibility than the act of listening for a message (SRP). Inheritance is such a strong statement (this IS-A that) that it should only be used in building type hierarchies and not for overriding use-specific behaviors and notifications. Chances are, if a class needs to be inherited to be used, it most likely is not designed as well as it could be in today's modern programming languages. So lets look at the other tools available to us for getting notified instead. Here's a few other choices to consider. Have the listener expose a MessageReceived event. Have the listener accept a new IMessageHandler interface instance. Have the listener accept an Action<Message> delegate. Really, all of these are different forms of delegation. Now, .NET events are a bit heavier than the other types of delegates in terms of run-time execution, but they are a great way to allow others using your class to subscribe to your events: 1: // using event - ommiting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private bool _isHalted = false; 6: private Thread _messageThread; 7:  8: // assign the subscriber and start the messaging loop 9: public MessageListener(ISubscriber subscriber) 10: { 11: _subscriber = subscriber; 12: _messageThread = new Thread(MessageLoop); 13: _messageThread.Start(); 14: } 15:  16: // user will override this to process their messages 17: public event Action<Message> MessageReceived; 18:  19: // handle the looping in the thread 20: private void MessageLoop() 21: { 22: while(!_isHalted) 23: { 24: // as long as processing, wait 1 second for message 25: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 26: if(msg != null && MessageReceived != null) 27: { 28: MessageReceived(msg); 29: } 30: } 31: } 32: } Note, now we can seal the class to avoid changes and the user just needs to provide a message handling method: 1: theListener.MessageReceived += CustomReceiveMethod; However, personally I don't think events hold up as well in this case because events are largely optional. To me, what is the point of a listener if you create one with no event listeners? So in my mind, use events when handling the notification is optional. So how about the delegation via interface? I personally like this method quite a bit. Basically what it does is similar to inheritance method mentioned first, but better because it makes it easy to split the part of the class that doesn't change (the base listener behavior) from the part that does change (the user-specified action after receiving a message). So assuming we had an interface like: 1: public interface IMessageHandler 2: { 3: void OnMessageReceived(Message receivedMessage); 4: } Our listener would look like this: 1: // using delegation via interface - omitting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private IMessageHandler _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, IMessageHandler handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // handle the looping in the thread 19: private void MessageLoop() 20: { 21: while(!_isHalted) 22: { 23: // as long as processing, wait 1 second for message 24: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 25: if(msg != null) 26: { 27: _handler.OnMessageReceived(msg); 28: } 29: } 30: } 31: } And they would call it by creating a class that implements IMessageHandler and pass that instance into the constructor of the listener. I like that this alleviates the issues of inheritance and essentially forces you to provide a handler (as opposed to events) on construction. Well, this is good, but personally I think we could go one step further. While I like this better than events or inheritance, it still forces you to implement a specific method name. What if that name collides? Furthermore if you have lots of these you end up either with large classes inheriting multiple interfaces to implement one method, or lots of small classes. Also, if you had one class that wanted to manage messages from two different subscribers differently, it wouldn't be able to because the interface can't be overloaded. This brings me to using delegates directly. In general, every time I think about creating an interface for something, and if that interface contains only one method, I start thinking a delegate is a better approach. Now, that said delegates don't accomplish everything an interface can. Obviously having the interface allows you to refer to the classes that implement the interface which can be very handy. In this case, though, really all you want is a method to handle the messages. So let's look at a method delegate: 1: // using delegation via delegate - omitting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private Action<Message> _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, Action<Message> handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // handle the looping in the thread 19: private void MessageLoop() 20: { 21: while(!_isHalted) 22: { 23: // as long as processing, wait 1 second for message 24: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 25: if(msg != null) 26: { 27: _handler(msg); 28: } 29: } 30: } 31: } Here the MessageListener now takes an Action<Message>.  For those of you unfamiliar with the pre-defined delegate types in .NET, that is a method with the signature: void SomeMethodName(Message). The great thing about delegates is it gives you a lot of power. You could create an anonymous delegate, a lambda, or specify any other method as long as it satisfies the Action<Message> signature. This way, you don't need to define an arbitrary helper class or name the method a specific thing. Incidentally, we could combine both the interface and delegate approach to allow maximum flexibility. Doing this, the user could either pass in a delegate, or specify a delegate interface: 1: // using delegation - give users choice of interface or delegate 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private Action<Message> _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, Action<Message> handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // passes the interface method as a delegate using method group 19: public MessageListener(ISubscriber subscriber, IMessageHandler handler) 20: : this(subscriber, handler.OnMessageReceived) 21: { 22: } 23:  24: // handle the looping in the thread 25: private void MessageLoop() 26: { 27: while(!_isHalted) 28: { 29: // as long as processing, wait 1 second for message 30: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 31: if(msg != null) 32: { 33: _handler(msg); 34: } 35: } 36: } 37: } } This is the method I tend to prefer because it allows the user of the class to choose which method works best for them. You may be curious about the actual performance of these different methods. 1: Enter iterations: 2: 1000000 3:  4: Inheritance took 4 ms. 5: Events took 7 ms. 6: Interface delegation took 4 ms. 7: Lambda delegate took 5 ms. Before you get too caught up in the numbers, however, keep in mind that this is performance over over 1,000,000 iterations. Since they are all < 10 ms which boils down to fractions of a micro-second per iteration so really any of them are a fine choice performance wise. As such, I think the choice of what to do really boils down to what you're trying to do. Here's my guidelines: Inheritance should be used only when defining a collection of related types with implementation specific behaviors, it should not be used as a hook for users to add their own functionality. Events should be used when subscription is optional or multi-cast is desired. Interface delegation should be used when you wish to refer to implementing classes by the interface type or if the type requires several methods to be implemented. Delegate method delegation should be used when you only need to provide one method and do not need to refer to implementers by the interface name.

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  • Switch vs Polymorphism when dealing with model and view

    - by Raphael Oliveira
    I can't figure out a better solution to my problem. I have a view controller that presents a list of elements. Those elements are models that can be an instance of B, C, D, etc and inherit from A. So in that view controller, each item should go to a different screen of the application and pass some data when the user select one of them. The two alternatives that comes to my mind are (please ignore the syntax, it is not a specific language) 1) switch (I know that sucks) //inside the view controller void onClickItem(int index) { A a = items.get(index); switch(a.type) { case b: B b = (B)a; go to screen X; x.v1 = b.v1; // fill X with b data x.v2 = b.v2; case c: go to screen Y; etc... } } 2) polymorphism //inside the view controller void onClickItem(int index) { A a = items.get(index); Screen s = new (a.getDestinationScreen()); //ignore the syntax s.v1 = a.v1; // fill s with information about A s.v2 = a.v2; show(s); } //inside B Class getDestinationScreen(void) { return Class(X); } //inside C Class getDestinationScreen(void) { return Class(Y); } My problem with solution 2 is that since B, C, D, etc are models, they shouldn't know about view related stuff. Or should they in that case?

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  • OpenGL Tessellation makes point

    - by urza57
    A little problem with my tessellation shader. I try to implement a simple tessellation shader but it only makes points. Here's my vertex shader : out vec4 ecPosition; out vec3 ecNormal; void main( void ) { vec4 position = gl_Vertex; gl_Position = gl_ModelViewProjectionMatrix * position; ecPosition = gl_ModelViewMatrix * position; ecNormal = normalize(gl_NormalMatrix * gl_Normal); } My tessellation control shader : layout(vertices = 3) out; out vec4 ecPosition3[]; in vec3 ecNormal[]; in vec4 ecPosition[]; out vec3 myNormal[]; void main() { gl_out[gl_InvocationID].gl_Position = gl_in[gl_InvocationID].gl_Position; myNormal[gl_InvocationID] = ecNormal[gl_InvocationID]; ecPosition3[gl_InvocationID] = ecPosition[gl_InvocationID]; gl_TessLevelOuter[0] = float(4.0); gl_TessLevelOuter[1] = float(4.0); gl_TessLevelOuter[2] = float(4.0); gl_TessLevelInner[0] = float(4.0); } And my Tessellation Evaluation shader: layout(triangles, equal_spacing, ccw) in; in vec3 myNormal[]; in vec4 ecPosition3[]; out vec3 ecNormal; out vec4 ecPosition; void main() { float u = gl_TessCoord.x; float v = gl_TessCoord.y; float w = gl_TessCoord.z; vec3 position = vec4(gl_in[0].gl_Position.xyz * u + gl_in[1].gl_Position.xyz * v + gl_in[2].gl_Position.xyz * w ); vec3 position2 = vec4(ecPosition3[0].xyz * u + ecPosition3[1].xyz * v + ecPosition3[2].xyz * w ); vec3 normal = myNormal[0] * u + myNormal[1] * v + myNormal[2] * w ); ecNormal = normal; gl_Position = vec4(position, 1.0); ecPosition = vec4(position2, 1.0); } Thank you !

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  • When does the "Do One Thing" paradigm become harmful?

    - by Petr
    For the sake of argument here's a sample function that prints contents of a given file line-by-line. Version 1: void printFile(const string & filePath) { fstream file(filePath, ios::in); string line; while (file.good()) { getline(file, line); cout << line << endl; } } I know it is recommended that functions do one thing at one level of abstraction. To me, though code above does pretty much one thing and is fairly atomic. Some books (such as Robert C. Martin's Clean Code) seem to suggest breaking the above code into separate functions. Version 2: void printLine(const string & line) { cout << line << endl; } void printLines(fstream & file) { string line; while (file.good()) { getline(file, line); printLine(line); } } void printFile(const string & filePath) { fstream file(filePath, ios::in); printLines(file); } I understand what they want to achieve (open file / read lines / print line), but isn't it a bit of overkill? The original version is simple and in some sense already does one thing - prints a file. The second version will lead to a large number of really small functions which may be far less legible than the first version. Wouldn't it be, in this case, better to have the code at one place? At which point does the "Do One Thing" paradigm become harmful?

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  • Problem with Ogre::Camera lookAt function when target is directly below.

    - by PigBen
    I am trying to make a class which controls a camera. It's pretty basic right now, it looks like this: class HoveringCameraController { public: void init(Ogre::Camera & camera, AnimatedBody & target, Ogre::Real height); void update(Ogre::Real time_delta); private: Ogre::Camera * camera_; AnimatedBody * target_; Ogre::Real height_; }; HoveringCameraController.cpp void HoveringCameraController::init(Ogre::Camera & camera, AnimatedBody & target, Ogre::Real height) { camera_ = &camera; target_ = &target; height_ = height; update(0.0); } void HoveringCameraController::update(Ogre::Real time_delta) { auto position = target_->getPosition(); position.y += height_; camera_->setPosition(position); camera_->lookAt(target_->getPosition()); } AnimatedBody is just a class that encapsulates an entity, it's animations and a scene node. The getPosition function is simply forwarded to it's scene node. What I want(for now) is for the camera to simply follow the AnimatedBody overhead at the distance given(the height parameter), and look down at it. It follows the object around, but it doesn't look straight down, it's tilted quite a bit in the positive Z direction. Does anybody have any idea why it would do that? If I change this line: position.y += height_; to this: position.x += height_; or this: position.z += height_; it does exactly what I would expect. It follows the object from the side or front, and looks directly at it.

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  • Mandelbrot set not displaying properly

    - by brainydexter
    I am trying to render mandelbrot set using glsl. I'm not sure why its not rendering the correct shape. Does the mandelbrot calculation require values to be within a range for the (x,y) [ or (real, imag) ] ? Here is a screenshot: I render a quad as follows: float w2 = 6; float h2 = 5; glBegin(GL_QUADS); glVertex3f(-w2, h2, 0.0); glVertex3f(-w2, -h2, 0.0); glVertex3f(w2, -h2, 0.0); glVertex3f(w2, h2, 0.0); glEnd(); My vertex shader: varying vec3 Position; void main(void) { Position = gl_Vertex.xyz; gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex; } My fragment shader (where all the meat is): uniform float MAXITERATIONS; varying vec3 Position; void main (void) { float zoom = 1.0; float centerX = 0.0; float centerY = 0.0; float real = Position.x * zoom + centerX; float imag = Position.y * zoom + centerY; float r2 = 0.0; float iter; for(iter = 0.0; iter < MAXITERATIONS && r2 < 4.0; ++iter) { float tempreal = real; real = (tempreal * tempreal) + (imag * imag); imag = 2.0 * real * imag; r2 = (real * real) + (imag * imag); } vec3 color; if(r2 < 4.0) color = vec3(1.0); else color = vec3( iter / MAXITERATIONS ); gl_FragColor = vec4(color, 1.0); }

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  • How can I Implement KeyListeners/ActionListeners into the JFrame?

    - by A.K.
    I'll get to the point: I have a player in my game that you control with the keyboard yet the key methods in the player class and ActionListener w/ KeyAdapter in the Board class don't seem to fire. So far I've tried adding these key methods into the JFrame, doesn't seem to let me move him even though other objects that I have (enemies) can move fine. Here's part of the JFrame class with the event listeners: frm.addKeyListener(KeyBoardListener); public void mouseClicked(MouseEvent e) { nSound.play(); StartB.setContentAreaFilled(false); cards.remove(StartB); frm.remove(TitleL); frm.remove(cards); frm.setLayout(new GridLayout(1, 1)); frm.add(nBoard); //Add Game "Tiles" Or Content. x = 1200 nBoard.setPreferredSize(new Dimension(1200, 420)); cards.revalidate(); frm.validate(); } public KeyListener KeyBoardListener = new KeyListener() { @Override public void keyPressed(KeyEvent args0) { int key = args0.getKeyCode(); if(key == KeyEvent.VK_LEFT) { nBoard.S.vx = -4; } if(key == KeyEvent.VK_RIGHT) { nBoard.S.vx = 4; } if(key == KeyEvent.VK_UP) { nBoard.S.vy = -4; } if(key == KeyEvent.VK_DOWN) { nBoard.S.vy = 4; } if(key == KeyEvent.VK_SPACE) { nBoard.S.fire(); } } @Override public void keyReleased(KeyEvent args0) { int key = args0.getKeyCode(); if(key == KeyEvent.VK_LEFT) { nBoard.S.vx = 0; } if(key == KeyEvent.VK_RIGHT) { nBoard.S.vx = 0; } if(key == KeyEvent.VK_UP) { nBoard.S.vy = 0; } if(key == KeyEvent.VK_DOWN) { nBoard.S.vy = 0; } } @Override public void keyTyped(KeyEvent args0) { // TODO Auto-generated method stub } };

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  • Java applet game design no keyboard focus

    - by Sri Harsha Chilakapati
    THIS IS PROBABLY THE WRONG PLACE. POSTED ITHERE (STACKOVERFLOW) I'm making an applet game and it is rendering, the game loop is running, the animations are updating, but the keyboard input is not working. Here's an SSCCE. public class Game extends JApplet implements Runnable { public void init(){ // Initialize the game when called by browser setFocusable(true); requestFocus(); requestFocusInWindow(); // Always returning false GInput.install(this); // Install the input manager for this class new Thread(this).start(); } public void run(){ startGameLoop(); } } And Here's the GInput class. public class GInput implements KeyListener { public static void install(Component c){ new GInput(c); } public GInput(Component c){ c.addKeyListener(this); } public void keyPressed(KeyEvent e){ System.out.println("A key has been pressed"); } ...... } This is my GInput class. When run as an applet, it doesn't work and when I add the Game class to a frame, it works properly. Thanks

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  • How do I implement SkyBox in xna 4.0 Reach Profile (for Windows Phone 7)?

    - by Biny
    I'm trying to Implement SkyBox in my phone game. Most of the samples in the web are for HiDef profile, and they are using custom effects (that not supported on Windows Phone). I've tried to follow this guide. But for some reason my SkyBox is not rendered. This is my SkyBox class: using System; using System.Collections.Generic; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Graphics; using Rocuna.Core; using Rocuna.GameEngine.Graphics; using Rocuna.GameEngine.Graphics.Components; namespace Rocuna.GameEngine.Extension.WP7.Graphics { /// <summary> /// Sky box element for phone games. /// </summary> public class SkyBox : SkyBoxBase { /// <summary> /// Initializes a new instance of the <see cref="SkyBoxBase"/> class. /// </summary> /// <param name="game">The Game that the game component should be attached to.</param> public SkyBox(TextureCube cube, Game game) : base(game) { Cube = cube; CubeFaces = new Texture2D[6]; PositionOffset = new Vector3(20, 20, 20); CreateGraphic(512); StripTexturesFromCube(); InitializeData(Game.GraphicsDevice); } #region Properties /// <summary> /// Gets or sets the position offset. /// </summary> /// <value> /// The position offset. /// </value> public Vector3 PositionOffset { get; set; } /// <summary> /// Gets or sets the position. /// </summary> /// <value> /// The position. /// </value> public Vector3 Position { get; set; } /// <summary> /// Gets or sets the cube. /// </summary> /// <value> /// The cube. /// </value> public TextureCube Cube { get; set; } /// <summary> /// Gets or sets the pixel array. /// </summary> /// <value> /// The pixel array. /// </value> public Color[] PixelArray { get; set; } /// <summary> /// Gets or sets the cube faces. /// </summary> /// <value> /// The cube faces. /// </value> public Texture2D[] CubeFaces { get; set; } /// <summary> /// Gets or sets the vertex buffer. /// </summary> /// <value> /// The vertex buffer. /// </value> public VertexBuffer VertexBuffer { get; set; } /// <summary> /// Gets or sets the index buffer. /// </summary> /// <value> /// The index buffer. /// </value> public IndexBuffer IndexBuffer { get; set; } /// <summary> /// Gets or sets the effect. /// </summary> /// <value> /// The effect. /// </value> public BasicEffect Effect { get; set; } #endregion protected override void LoadContent() { } public override void Update(GameTime gameTime) { var camera = Game.GetService<GraphicManager>().CurrentCamera; this.Position = camera.Position + PositionOffset; base.Update(gameTime); } public override void Draw(GameTime gameTime) { DrawOrder = int.MaxValue; var graphics = Effect.GraphicsDevice; graphics.DepthStencilState = new DepthStencilState() { DepthBufferEnable = false }; graphics.RasterizerState = new RasterizerState() { CullMode = CullMode.None }; graphics.BlendState = new BlendState(); graphics.SamplerStates[0] = SamplerState.AnisotropicClamp; graphics.SetVertexBuffer(VertexBuffer); graphics.Indices = IndexBuffer; Effect.Texture = CubeFaces[0]; Effect.CurrentTechnique.Passes[0].Apply(); graphics.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, _vertices.Count, 0, 2); Effect.Texture = CubeFaces[1]; Effect.CurrentTechnique.Passes[0].Apply(); graphics.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, _vertices.Count, 6, 2); Effect.Texture = CubeFaces[2]; Effect.CurrentTechnique.Passes[0].Apply(); graphics.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, _vertices.Count, 12, 2); Effect.Texture = CubeFaces[3]; Effect.CurrentTechnique.Passes[0].Apply(); graphics.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, _vertices.Count, 18, 2); Effect.Texture = CubeFaces[4]; Effect.CurrentTechnique.Passes[0].Apply(); graphics.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, _vertices.Count, 24, 2); Effect.Texture = CubeFaces[5]; Effect.CurrentTechnique.Passes[0].Apply(); graphics.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, _vertices.Count, 30, 2); base.Draw(gameTime); } #region Fields private List<VertexPositionNormalTexture> _vertices = new List<VertexPositionNormalTexture>(); private List<ushort> _indices = new List<ushort>(); #endregion #region Private methods private void InitializeData(GraphicsDevice graphicsDevice) { VertexBuffer = new VertexBuffer(graphicsDevice, typeof(VertexPositionNormalTexture), _vertices.Count, BufferUsage.None); VertexBuffer.SetData<VertexPositionNormalTexture>(_vertices.ToArray()); // Create an index buffer, and copy our index data into it. IndexBuffer = new IndexBuffer(graphicsDevice, typeof(ushort), _indices.Count, BufferUsage.None); IndexBuffer.SetData<ushort>(_indices.ToArray()); // Create a BasicEffect, which will be used to render the primitive. Effect = new BasicEffect(graphicsDevice); Effect.TextureEnabled = true; Effect.EnableDefaultLighting(); } private void CreateGraphic(float size) { Vector3[] normals = { Vector3.Right, Vector3.Left, Vector3.Up, Vector3.Down, Vector3.Backward, Vector3.Forward, }; Vector2[] textureCoordinates = { Vector2.One, Vector2.UnitY, Vector2.Zero, Vector2.UnitX, Vector2.Zero, Vector2.UnitX, Vector2.One, Vector2.UnitY, Vector2.Zero, Vector2.UnitX, Vector2.One, Vector2.UnitY, Vector2.Zero, Vector2.UnitX, Vector2.One, Vector2.UnitY, Vector2.UnitY, Vector2.Zero, Vector2.UnitX, Vector2.One, Vector2.UnitY, Vector2.Zero, Vector2.UnitX, Vector2.One, }; var index = 0; foreach (var normal in normals) { var side1 = new Vector3(normal.Z, normal.X, normal.Y); var side2 = Vector3.Cross(normal, side1); AddIndex(CurrentVertex + 0); AddIndex(CurrentVertex + 1); AddIndex(CurrentVertex + 2); AddIndex(CurrentVertex + 0); AddIndex(CurrentVertex + 2); AddIndex(CurrentVertex + 3); AddVertex((normal - side1 - side2) * size / 2, normal, textureCoordinates[index++]); AddVertex((normal - side1 + side2) * size / 2, normal, textureCoordinates[index++]); AddVertex((normal + side1 + side2) * size / 2, normal, textureCoordinates[index++]); AddVertex((normal + side1 - side2) * size / 2, normal, textureCoordinates[index++]); } } protected void StripTexturesFromCube() { PixelArray = new Color[Cube.Size * Cube.Size]; for (int s = 0; s < CubeFaces.Length; s++) { CubeFaces[s] = new Texture2D(Game.GraphicsDevice, Cube.Size, Cube.Size, false, SurfaceFormat.Color); switch (s) { case 0: Cube.GetData<Color>(CubeMapFace.PositiveX, PixelArray); CubeFaces[s].SetData<Color>(PixelArray); break; case 1: Cube.GetData(CubeMapFace.NegativeX, PixelArray); CubeFaces[s].SetData(PixelArray); break; case 2: Cube.GetData(CubeMapFace.PositiveY, PixelArray); CubeFaces[s].SetData(PixelArray); break; case 3: Cube.GetData(CubeMapFace.NegativeY, PixelArray); CubeFaces[s].SetData(PixelArray); break; case 4: Cube.GetData(CubeMapFace.PositiveZ, PixelArray); CubeFaces[s].SetData(PixelArray); break; case 5: Cube.GetData(CubeMapFace.NegativeZ, PixelArray); CubeFaces[s].SetData(PixelArray); break; } } } protected void AddVertex(Vector3 position, Vector3 normal, Vector2 textureCoordinates) { _vertices.Add(new VertexPositionNormalTexture(position, normal, textureCoordinates)); } protected void AddIndex(int index) { if (index > ushort.MaxValue) throw new ArgumentOutOfRangeException("index"); _indices.Add((ushort)index); } protected int CurrentVertex { get { return _vertices.Count; } } #endregion } }

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  • Using runtime generic type reflection to build a smarter DAO

    - by kerry
    Have you ever wished you could get the runtime type of your generic class? I wonder why they didn’t put this in the language. It is possible, however, with reflection: Consider a data access object (DAO) (note: I had to use brackets b/c the arrows were messing with wordpress): public interface Identifiable { public Long getId(); } public interface Dao { public T findById(Long id); public void save(T obj); public void delete(T obj); } Using reflection, we can create a DAO implementation base class, HibernateDao, that will work for any object: import java.lang.reflect.Field; import java.lang.reflect.ParameterizedType; public class HibernateDao implements Dao { private final Class clazz; public HibernateDao(Session session) { // the magic ParameterizedType parameterizedType = (ParameterizedType) clazz.getGenericSuperclass(); return (Class) parameterizedType.getActualTypeArguments()[0]; } public T findById(Long id) { return session.get(clazz, id); } public void save(T obj) { session.saveOrUpdate(obj); } public void delete(T obj) { session.delete(obj); } } Then, all we have to do is extend from the class: public class BookDaoHibernateImpl extends HibernateDao { }

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  • How do I separate codes with classes?

    - by Trycon
    I have this main class: package javagame; import org.newdawn.slick.GameContainer; import org.newdawn.slick.Graphics; import org.newdawn.slick.SlickException; import org.newdawn.slick.state.BasicGameState; import org.newdawn.slick.state.StateBasedGame; public class tests extends BasicGameState{ public boolean render=false; tests1 test = new tests1(); public tests(int test) { // TODO Auto-generated constructor stub } @Override public void init(GameContainer arg0, StateBasedGame arg1) throws SlickException { // TODO Auto-generated method stub } @Override public void render(GameContainer arg0, StateBasedGame arg1, Graphics g) throws SlickException { // TODO Auto-generated method stub if(render==true) { g.drawString("Hello",100,100); } } @Override public void update(GameContainer gc, StateBasedGame s, int delta) throws SlickException { // TODO Auto-generated method stub test.render=render; test.update(gc, s, delta); } @Override public int getID() { // TODO Auto-generated method stub return 1000; } } and its sub-class: package javagame; import org.newdawn.slick.GameContainer; import org.newdawn.slick.Input; import org.newdawn.slick.state.StateBasedGame; public class tests1 { public boolean render; public void update(GameContainer gc, StateBasedGame s, int delta) { Input input = gc.getInput(); if(input.isKeyPressed(Input.KEY_X)) { render=true; } } } I was finding a way to prevent many codes in one class. I'm new to java. When I try running my game, then when I press X, it does not work. How am I suppose to fix that?

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  • Flixel: doesn't light tile up

    - by Arno
    i'm creating a game with flixel, and I want to have a effect when you mouse over a tile, I tried implementing it, and this is what it gives: public class GameState extends FlxState { private var block:EmptyBlock; public function GameState() { } override public function create():void { for (var i:Number = 0; i < 30; i++) { block = new EmptyBlock(i, 20); block.create(); } } override public function update():void { block.update(); super.update(); } } } GameState class and here is the EmptyBlock class: public class EmptyBlock { private var x:int; private var y:int; private var row:FlxRect public function EmptyBlock(x:int, y:int ) { this.x = x; this.y = y; } public function create():void { row = new FlxRect(x, y, 32, 32); trace ("Created block at" + x + y); } public function update():void { if (FlxG.mouse.screenX == row.x) { if (FlxG.mouse.screenY == row.y) { var outline:FlxSprite = new FlxSprite(row.x, row.y).makeGraphic(row.width, row.height, 0x002525); } } } } }

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  • How to make a player stay within bounds of world with 2D Camera

    - by Craig
    Im creating a simple top down survival game. At the moment, i have the sprite which is a ship and moves by rotating left or right then going forward in that direction. I have implemented a 2D camera, its always centered on the player. However, when i move towards the bounds of the world that the sprite is in it just keeps on going :( How to i sort it that it stops at the edge of the world and cant go beyond it? Cheers :) Below is the main game class using System; using System.Collections.Generic; using System.Linq; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Audio; using Microsoft.Xna.Framework.Content; using Microsoft.Xna.Framework.GamerServices; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework.Input; using Microsoft.Xna.Framework.Media; namespace GamesCoursework_1 { /// <summary> /// This is the main type for your game /// </summary> public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; // player variables Texture2D Ship; Vector2 Ship_Position; float Ship_Rotation = 0.0f; Vector2 Ship_Origin; Vector2 Ship_Velocity; const float tangentialVelocity = 4f; float friction = 0.05f; static Point CameraViewport = new Point(800, 800); Camera2d cam = new Camera2d((int)CameraViewport.X, (int)CameraViewport.Y); //Size of world static Point worldSize = new Point(1600, 1600); // Screen variables static Point worldCenter = new Point(worldSize.X / 2, worldSize.Y / 2); Rectangle playerBounds = new Rectangle(CameraViewport.X / 2, CameraViewport.Y / 2, worldSize.X - CameraViewport.X, worldSize.Y - CameraViewport.Y); Rectangle worldBounds = new Rectangle(0, 0, worldSize.X, worldSize.Y); Texture2D background; public Game1() { graphics = new GraphicsDeviceManager(this); graphics.PreferredBackBufferWidth = CameraViewport.X; graphics.PreferredBackBufferHeight = CameraViewport.Y; Content.RootDirectory = "Content"; } /// <summary> /// Allows the game to perform any initialization it needs to before starting to run. /// This is where it can query for any required services and load any non-graphic /// related content. Calling base.Initialize will enumerate through any components /// and initialize them as well. /// </summary> protected override void Initialize() { // TODO: Add your initialization logic here base.Initialize(); } /// <summary> /// LoadContent will be called once per game and is the place to load /// all of your content. /// </summary> protected override void LoadContent() { // Create a new SpriteBatch, which can be used to draw textures. spriteBatch = new SpriteBatch(GraphicsDevice); // TODO: use this.Content to load your game content here Ship = Content.Load<Texture2D>("Ship"); Ship_Origin.X = Ship.Width / 2; Ship_Origin.Y = Ship.Height / 2; background = Content.Load<Texture2D>("aus"); Ship_Position = new Vector2(worldCenter.X, worldCenter.Y); cam.Pos = Ship_Position; cam.Zoom = 1f; } /// <summary> /// UnloadContent will be called once per game and is the place to unload /// all content. /// </summary> protected override void UnloadContent() { // TODO: Unload any non ContentManager content here } /// <summary> /// Allows the game to run logic such as updating the world, /// checking for collisions, gathering input, and playing audio. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> protected override void Update(GameTime gameTime) { // Allows the game to exit if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed) this.Exit(); // TODO: Add your update logic here Ship_Position = Ship_Velocity + Ship_Position; keyPressed(); base.Update(gameTime); } /// <summary> /// This is called when the game should draw itself. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); // TODO: Add your drawing code here spriteBatch.Begin(SpriteSortMode.Deferred, BlendState.AlphaBlend, null, null, null,null, cam.get_transformation(GraphicsDevice)); spriteBatch.Draw(background, Vector2.Zero, Color.White); spriteBatch.Draw(Ship, Ship_Position, Ship.Bounds, Color.White, Ship_Rotation, Ship_Origin, 1.0f, SpriteEffects.None, 0f); spriteBatch.End(); base.Draw(gameTime); } private void Ship_Move(Vector2 move) { Ship_Position += move; } private void keyPressed() { KeyboardState keyState; // Move right keyState = Keyboard.GetState(); if (keyState.IsKeyDown(Keys.Right)) { Ship_Rotation = Ship_Rotation + 0.1f; } if (keyState.IsKeyDown(Keys.Left)) { Ship_Rotation = Ship_Rotation - 0.1f; } if (keyState.IsKeyDown(Keys.Up)) { Ship_Velocity.X = (float)Math.Cos(Ship_Rotation) * tangentialVelocity; Ship_Velocity.Y = (float)Math.Sin(Ship_Rotation) * tangentialVelocity; if ((int)Ship_Position.Y < playerBounds.Bottom && (int)Ship_Position.Y > playerBounds.Top) cam._pos.Y = Ship_Position.Y; if ((int)Ship_Position.X > playerBounds.Left && (int)Ship_Position.X < playerBounds.Right) cam._pos.X = Ship_Position.X; //tried world bounds here if (!worldBounds.Contains(new Point((int)Ship_Position.X, (int)Ship_Position.Y))) Ship_Position -= new Vector2(0.0f, -tangentialVelocity * 2); if (!worldBounds.Contains(new Point((int)Ship_Position.X, (int)Ship_Position.Y))) Ship_Position -= new Vector2(0.0f, 2 * tangentialVelocity); } else if(Ship_Velocity != Vector2.Zero) { float i = Ship_Velocity.X; float j = Ship_Velocity.Y; Ship_Velocity.X = i -= friction * i; Ship_Velocity.Y = j -= friction * j; if ((int)Ship_Position.Y < playerBounds.Bottom && (int)Ship_Position.Y > playerBounds.Top) cam._pos.Y = Ship_Position.Y; if ((int)Ship_Position.X > playerBounds.Left && (int)Ship_Position.X < playerBounds.Right) cam._pos.X = Ship_Position.X; } if (keyState.IsKeyDown(Keys.Q)) { if (cam.Zoom < 2f) cam.Zoom += 0.05f; } if (keyState.IsKeyDown(Keys.A)) { if (cam.Zoom > 0.3f) cam.Zoom -= 0.05f; } } } } my 2d camera class using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Graphics; namespace GamesCoursework_1 { public class Camera2d { protected float _zoom; // Camera Zoom public Matrix _transform; // Matrix Transform public Vector2 _pos; // Camera Position protected float _rotation; // Camera Rotation public int _viewportWidth, _viewportHeight; // viewport size public Camera2d(int ViewportWidth, int ViewportHeight) { _zoom = 1.0f; _rotation = 0.0f; _pos = Vector2.Zero; _viewportWidth = ViewportWidth; _viewportHeight = ViewportHeight; } // Sets and gets zoom public float Zoom { get { return _zoom; } set { _zoom = value; if (_zoom < 0.1f) _zoom = 0.1f; } // Negative zoom will flip image } public float Rotation { get { return _rotation; } set { _rotation = value; } } // Auxiliary function to move the camera public void Move(Vector2 amount) { _pos += amount; } // Get set position public Vector2 Pos { get { return _pos; } set { _pos = value; } } public Matrix get_transformation(GraphicsDevice graphicsDevice) { _transform = // Thanks to o KB o for this solution Matrix.CreateTranslation(new Vector3(-_pos.X, -_pos.Y, 0)) * Matrix.CreateRotationZ(Rotation) * Matrix.CreateScale(new Vector3(Zoom, Zoom, 1)) * Matrix.CreateTranslation(new Vector3(_viewportWidth * 0.5f, _viewportHeight * 0.5f, 0)); return _transform; } } }

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  • Java: How to Make a Player Class in a Tile-Based RPG

    - by A.K.
    So I've been following a JavaHub tutorial that basically uses a pixel engine similar to MiniCraft. I've attempted to make a Player Class as such, and I'm basically making a mock Pokemon game for learning's sake: package pokemon.entity; import java.awt.Rectangle; import pokemon.gfx.Screen; import pokemon.levelgen.Tile; import pokemon.entity.SpritesManage;; public class Player { int x, y; int vx, vy; public Rectangle AshRec; public Sprite AshSprite; Screen screen; Sprite[][] AshSheet; public Player() { AshSprite = SpritesManage.AshSheet[1][0]; AshRec = new Rectangle(0, 0, 16, 16); x = 0; y = 0; vx = 1; vy = 1; screen.renderSprite(0, 0, AshSprite); } public void update() { move(); checkCollision(); } private void checkCollision() { } private void move() { AshRec.x += vx; AshRec.y += vy; } public void render(Screen screen, int x, int y) { screen.renderSprite(x, y, AshSprite); } } I guess what I really want to do is have the Player centered in the screen and have the sprite drawn based on an Input Handler. I'm just stumped as to how to sync these together.

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  • keyPressed is not working after adding ActionListener to JButton

    - by Yehonatan
    I have a serious problem while trying to build a menu for my game. I've added two JButton to a main JPanel and added an ActionListener for each of them. The main JPanel also contains the game JPanel which have the keyPressed method inside keyController. That's how it looks - Main -       JPanel -         JButton, JButton,         JPanel which contains the game and keyPressed function inside KeyController class which worked fine before I added the ActionListener for JButton. For some reason after I added an ActionListener for each of the button, the game JPanel is not getting any keyPreseed events nor KeyRealesed. Does anyone know the solution for my situation? Thank you very much! Main window - Scanner in = new Scanner(System.in); JFrame f = new JFrame("Square V.S Circles"); f.setUndecorated(true); f.setResizable(false); f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); f.add(new JPanelHandler()); f.pack(); f.setVisible(true); f.setLocationRelativeTo(null); JPanelHandler(main JPanel) - super.setFocusable(true); JButton mybutton = new JButton("Quit"); JButton sayhi = new JButton("Say hi"); sayhi.addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { System.out.println("Hi"); } }); mybutton.addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { System.exit(0); } }); add(mybutton); add(sayhi); add(new Board(2)); Board KeyController(The code inside is working so it's unnecessary to put it here) - private class KeyController extends KeyAdapter { public KeyController() { ..Code } @Override public void keyPressed(KeyEvent e) { ...Code } @Override public void keyReleased(KeyEvent e){ ...Code } }

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  • How to blend the sprite into background?

    - by optimisez
    I try to blend the character into game but I still cannot remove the blue color in the sprite sheet and discover that the white area of sprite is semi-transparent. Before that, the color D3DCOLOR_XRGB(255, 255, 255) is set in D3DXCreateTextureFromFileEx. You will see the fireball through the sprite. After I change the color to D3DCOLOR_XRGB(0, 255, 255), the result will be Now, I am trying to remove the blue color of the sprite sheet and my expected result is something like that Until now, I still cannot figure out how to do that. Any ideas? void initPlayer() { // Create texture. hr = D3DXCreateTextureFromFileEx(d3dDevice, "player.png", 169, 44, D3DX_DEFAULT, NULL, D3DFMT_A8R8G8B8, D3DPOOL_MANAGED, D3DX_DEFAULT, D3DX_DEFAULT, D3DCOLOR_XRGB(0, 255, 255), NULL, NULL, &player); } void renderPlayer() { sprite->Draw(player, &playerRect, NULL, &D3DXVECTOR3(playerDest.X, playerDest.Y, 0),D3DCOLOR_XRGB(255, 255, 255)); } void initFireball() { hr = D3DXCreateTextureFromFileEx(d3dDevice, "fireball.png", 512, 512, D3DX_DEFAULT, NULL, D3DFMT_A8R8G8B8, D3DPOOL_MANAGED, D3DX_DEFAULT, D3DX_DEFAULT, D3DCOLOR_XRGB(255, 255, 255), NULL, NULL, &fireball); } void renderFireball() { sprite->Draw(fireball, &fireballRect, NULL, &D3DXVECTOR3(fireballDest.X, fireballDest.Y, 0), D3DCOLOR_XRGB(255,255, 255)); }

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  • Using visitor pattern with large object hierarchy

    - by T. Fabre
    Context I've been using with a hierarchy of objects (an expression tree) a "pseudo" visitor pattern (pseudo, as in it does not use double dispatch) : public interface MyInterface { void Accept(SomeClass operationClass); } public class MyImpl : MyInterface { public void Accept(SomeClass operationClass) { operationClass.DoSomething(); operationClass.DoSomethingElse(); // ... and so on ... } } This design was, however questionnable, pretty comfortable since the number of implementations of MyInterface is significant (~50 or more) and I didn't need to add extra operations. Each implementation is unique (it's a different expression or operator), and some are composites (ie, operator nodes that will contain other operator/leaf nodes). Traversal is currently performed by calling the Accept operation on the root node of the tree, which in turns calls Accept on each of its child nodes, which in turn... and so on... But the time has come where I need to add a new operation, such as pretty printing : public class MyImpl : MyInterface { // Property does not come from MyInterface public string SomeProperty { get; set; } public void Accept(SomeClass operationClass) { operationClass.DoSomething(); operationClass.DoSomethingElse(); // ... and so on ... } public void Accept(SomePrettyPrinter printer) { printer.PrettyPrint(this.SomeProperty); } } I basically see two options : Keep the same design, adding a new method for my operation to each derived class, at the expense of maintainibility (not an option, IMHO) Use the "true" Visitor pattern, at the expense of extensibility (not an option, as I expect to have more implementations coming along the way...), with about 50+ overloads of the Visit method, each one matching a specific implementation ? Question Would you recommand using the Visitor pattern ? Is there any other pattern that could help solve this issue ?

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  • Seperation of drawing and logic in games

    - by BFree
    I'm a developer that's just now starting to mess around with game development. I'm a .Net guy, so I've messed with XNA and am now playing around with Cocos2d for the iPhone. My question really is more general though. Let's say I'm building a simple Pong game. I'd have a Ball class and a Paddle class. Coming from the business world development, my first instinct is to not have any drawing or input handling code in either of these classes. //pseudo code class Ball { Vector2D position; Vector2D velocity; Color color; void Move(){} } Nothing in the ball class handles input, or deals with drawing. I'd then have another class, my Game class, or my Scene.m (in Cocos2D) which would new up the Ball, and during the game loop, it would manipulate the ball as needed. The thing is though, in many tutorials for both XNA and Cocos2D, I see a pattern like this: //pseudo code class Ball : SomeUpdatableComponent { Vector2D position; Vector2D velocity; Color color; void Update(){} void Draw(){} void HandleInput(){} } My question is, is this right? Is this the pattern that people use in game development? It somehow goes against everything I'm used to, to have my Ball class do everything. Furthermore, in this second example, where my Ball knows how to move around, how would I handle collision detection with the Paddle? Would the Ball need to have knowledge of the Paddle? In my first example, the Game class would have references to both the Ball and the Paddle, and then ship both of those off to some CollisionDetection manager or something, but how do I deal with the complexity of various components, if each individual component does everything themselves? (I hope I'm making sense.....)

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  • Best practice to collect information from child objects

    - by Markus
    I'm regularly seeing the following pattern: public abstract class BaseItem { BaseItem[] children; // ... public void DoSomethingWithStuff() { StuffCollection collection = new StuffCollection(); foreach(child c : children) c.AddRequiredStuff(collection); // do something with the collection ... } public abstract void AddRequiredStuff(StuffCollection collection); } public class ConcreteItem : BaseItem { // ... public override void AddRequiredStuff(StuffCollection collection) { Stuff stuff; // ... collection.Add(stuff); } } Where I would use something like this, for better information hiding: public abstract class BaseItem { BaseItem[] children; // ... public void DoSomethingWithStuff() { StuffCollection collection = new StuffCollection(); foreach(child c : children) collection.AddRange(c.RequiredStuff()); // do something with the collection ... } public abstract StuffCollection RequiredStuff(); } public class ConcreteItem : BaseItem { // ... public override StuffCollection RequiredStuff() { StuffCollection stuffCollection; Stuff stuff; // ... stuffCollection.Add(stuff); return stuffCollection; } } What are pros and cons of each solution? For me, giving the implementation access to parent's information is some how disconcerting. On the other hand, initializing a new list, just to collect the items is a useless overhead ... What is the better design? How would it change, if DoSomethingWithStuff wouldn't be part of BaseItem but a third class? PS: there might be missing semicolons, or typos; sorry for that! The above code is not meant to be executed, but just for illustration.

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  • Dependency Injection: where to store dependencies used by only one method?

    - by simoneL
    I developing a project integrated with Dependency Injection (just for reference, I'm using Unity). The problem is that I have some Manager classes with several methods and in many cases I have dependencies used only in one method. public class UserManager : IUserManager { private UserRepository UserRepository {get;set;} private TeamRepository TeamRepository {get;set;} private CacheRepository CacheRepository {get;set;} private WorkgroupRepository WorkgroupRepository {get;set;} public UserManager(UserRepository userRepository, TeamRepository teamRepository, CacheRepository cacheRepository , WorkgroupRepository workgroupRepository, ... // Many other dependencies ) { UserRepository = userRepository; TeamRepository = teamRepository; CacheRepository = cacheRepository ; WorkgroupRepository = workgroupRepository; ... // Setting the remaining dependencies } public void GetLatestUser(){ // Uses only UserRepository } public void GetUsersByTeam(int teamID){ // Uses only TeamRepository } public void GetUserHistory(){ // Uses only CacheRepository } public void GetUsersByWorkgroup(int workgroupID){ // Uses only workgroupRepository } } The UserManager is instantiated in this way: DependencyFactory<IUserManager>(); Note: DependencyFactory is just a wrapper to simplify the access to the UnityContainer Is it OK to have classes like that in the example? Is there a better way to implement avoiding to instantiate all the unnecessary dependencies?

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  • C programming multiple storage backends

    - by ahjmorton
    I am starting a side project in C which requires multiple storage backends to be driven by a particular piece of logic. These storage backends would each be linked with the decision of which one to use specified at runtime. So for example if I invoke my program with one set of parameters it will perform the operations in memory but if I change the program configuration it would write to disk. The underlying idea is that each storage backend should implement the same protocol. In other words the logic for performing operations should need to know which backend it is operating on. Currently the way I have thought to provide this indirection is to have a struct of function pointers with the logic calling these function pointers. Essentially the struct would contain all the operations needed to implement the higher level logic E.g. struct Context { void (* doPartOfDoOp)(void) int (* getResult)(void); } //logic.h void doOp(Context * context) { //bunch of stuff context->doPartOfDoOp(); } int getResult(Context * context) { //bunch of stuff return context->getResult(); } My questions is if this way of solving the problem is one a C programmer would understand? I am a Java developer by trade but enjoy using C/++. Essentially the Context struct provides an interface like level of indirection. However I would like to know if there is a more idiomatic way of achieving this.

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  • Update UI in the main activity through handler in a thread (Android)

    - by Hrk
    Hello, I try to make several connection in a class and update the multiple progressbar in the main screen. But I've got the following error trying to use thread in android : Code: 05-06 13:13:11.092: ERROR/ConnectionManager(22854): ERROR:Can't create handler inside thread that has not called Looper.prepare() Here is a small part of my code in the main Activity public class Act_Main extends ListActivity { private ConnectionManager cm; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // Set up the window layout requestWindowFeature(Window.FEATURE_CUSTOM_TITLE); setContentView(R.layout.main); getWindow().setFeatureInt(Window.FEATURE_CUSTOM_TITLE, R.layout.custom_title); } public void startConnection() { //open DB connection db = new DBAdapter(getApplicationContext()); db.open(); cm = new ConnectionManager(handler, db); showDialog(DIALOG_PROGRESS_LOGIN); } @Override public void onStart() { super.onStart(); startConnection(); } protected Dialog onCreateDialog(int id) { switch (id) { case DIALOG_PROGRESS_LOGIN: progressDialog = new ProgressDialog(Act_Main.this); progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL); progressDialog.setMessage("Connecting.\nPlease wait..."); progressThreadLogin = new ProgressThreadLogin(); progressThreadLogin.start(); return progressDialog; case DIALOG_PROGRESS_NETWORK: [b]progressDialog = new ProgressDialog(Act_Main.this);[/b] progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL); progressDialog.setMessage("Loading entire network.\nPlease wait..."); progressThreadNetwork = new ProgressThreadNetwork(); progressThreadNetwork.start(); return progressDialog; default: return null; } } // Define the Handler that receives messages from the thread and update the progress final Handler handler = new Handler() { public void handleMessage(Message msg) { int total = msg.getData().getInt("total"); int step = msg.getData().getInt("step"); Log.d(TAG, "handleMessage:PROCESSBAR:"+total); progressDialog.setProgress(total); if (total >= 100) { switch (step) { case UPDATE_NETWORK: dismissDialog(DIALOG_PROGRESS_LOGIN); showDialog(DIALOG_PROGRESS_NETWORK); cm.getNetwork(); break; .... default: break; } } } }; private class ProgressThreadLogin extends Thread { ProgressThreadLogin() { } public void run() { cm.login(); } } private class ProgressThreadNetwork extends Thread { ProgressThreadNetwork() { } public void run() { cm.getNetwork(); } } } And my connectionManager class: public class ConnectionManager { public ConnectionManager(Handler handler, DBAdapter db) { this.handler = handler; this.db = db; } public void updateProgressBar(int step, int value) { if (value == 0) total = total+1; else total = value ; Message msg = handler.obtainMessage(); Bundle b = new Bundle(); b.putInt("total", total); b.putInt("step", step); msg.setData(b); handler.handleMessage(msg); } public void login() { //DO MY LOGIN TASK updateProgressBar(Act_Main.UPDATE_NETWORK, 100); } } The crash errors occurs on the first line of "case DIALOG_PROGRESS_NETWORK:". My first progressbar is hidden but the second one is not displayed. I think I've done somthing wrong using the threads and handlers but I dont' know why. I was first using handler.sendMessage in place of handler.handleMessage but when I had several task in my connectionManager, the progressbar was updated only at the end of all tasks. Thank you in advance for your help

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  • How to take the snapshot of a IE webpage through a BHO (C#)

    - by Kapil
    Hi, I am trying to build an IE BHO in C# for taking the snapshot of a webpage loaded in the IE browser. Here is what I'm trying to do: public class ShowToolbarBHO : BandObjectLib.IObjectWithSite { IWebBrowser2 webBrowser = null; public void SetSite (Object site) { ....... if (site != null) { ...... webBrowser = (IWebBrowser2)site; ...... } } } Also, I p/invoke the following COM methods: [Guid("0000010D-0000-0000-C000-000000000046")] [InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)] [ComImportAttribute()] public interface IViewObject { void Draw([MarshalAs(UnmanagedType.U4)] int dwDrawAspect, int lindex, IntPtr pvAspect, [In] IntPtr ptd, IntPtr hdcTargetDev, IntPtr hdcDraw, [MarshalAs(UnmanagedType.LPStruct)] ref COMRECT lprcBounds, [In] IntPtr lprcWBounds, IntPtr pfnContinue, int dwContinue); int GetColorSet([MarshalAs(UnmanagedType.U4)] int dwDrawAspect, int lindex, IntPtr pvAspect, [In] IntPtr ptd, IntPtr hicTargetDev, [Out] IntPtr ppColorSet); int Freeze([MarshalAs(UnmanagedType.U4)] int dwDrawAspect, int lindex, IntPtr pvAspect, out IntPtr pdwFreeze); int Unfreeze([MarshalAs(UnmanagedType.U4)] int dwFreeze); int SetAdvise([MarshalAs(UnmanagedType.U4)] int aspects, [MarshalAs(UnmanagedType.U4)] int advf, [MarshalAs(UnmanagedType.Interface)] IAdviseSink pAdvSink); void GetAdvise([MarshalAs(UnmanagedType.LPArray)] out int[] paspects, [MarshalAs(UnmanagedType.LPArray)] out int[] advf, [MarshalAs(UnmanagedType.LPArray)] out IAdviseSink[] pAdvSink); } [StructLayoutAttribute(LayoutKind.Sequential)] public class COMRECT { public int left; public int top; public int right; public int bottom; public COMRECT() { } public COMRECT(int left, int top, int right, int bottom) { this.left = left; this.top = top; this.right = right; this.bottom = bottom; } } [InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)] [ComVisibleAttribute(true)] [GuidAttribute("0000010F-0000-0000-C000-000000000046")] [ComImportAttribute()] public interface IAdviseSink { void OnDataChange([In]IntPtr pFormatetc, [In]IntPtr pStgmed); void OnViewChange([MarshalAs(UnmanagedType.U4)] int dwAspect, [MarshalAs(UnmanagedType.I4)] int lindex); void OnRename([MarshalAs(UnmanagedType.Interface)] object pmk); void OnSave(); void OnClose(); } Now When I take the snapshot: I make a call CaptureWebScreenImage((IHTMLDocument2) webBrowser.document); public static Image CaptureWebScreenImage(IHTMLDocument2 myDoc) { int heightsize = (int)getDocumentAttribute(myDoc, "scrollHeight"); int widthsize = (int)getDocumentAttribute(myDoc, "scrollWidth"); Bitmap finalImage = new Bitmap(widthsize, heightsize); Graphics gFinal = Graphics.FromImage(finalImage); COMRECT rect = new COMRECT(); rect.left = 0; rect.top = 0; rect.right = widthsize; rect.bottom = heightsize; IntPtr hDC = gFinal.GetHdc(); IViewObject vO = myDoc as IViewObject; vO.Draw(1, -1, (IntPtr)0, (IntPtr)0, (IntPtr)0, (IntPtr)hDC, ref rect, (IntPtr)0, (IntPtr)0, 0); gFinal.ReleaseHdc(); gFinal.Dispose(); return finalImage; } I am not getting the image of the webpage. Rather I am getting an image with black background. I am not sure if this is the right way of doing it, but I found over the web that IViewObject::Draw method is used for taking the image of a webpage in IE. I was earlier doing the image capture using the Native PrintWindow() method as mentioned in the following codeproject's page - http://www.codeproject.com/KB/graphics/IECapture.aspx But the image size is humongous! I was trying to see if I can reduce the size by using other techniques. It would be great if someone can point out the mistakes (I am sure there would be many) in my code above. Thanks, Kapil

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  • Is Inheritance in Struts2 Model-Driven Action possible?

    - by mryan
    Hello, I have a Model-Driven Struts2 action that provides correct JSON response. When I re-structure the action I get an empty JSON response back. Has anyone got inheritance working with Struts2 Model-Driven actions? Ive tried explicitly setting include properties in struts config: <result name="json" type="json"> <param name="includeProperties"> jsonResponse </param> </result> Code for all actions below - not actual code in use - I have edited and stripped down for clarity. Thanks in advance. Action providing correct response: public class Bike extends ActionSupport implements ModelDriven, Preparable { @Autowired private Service bikeService; private JsonResponse jsonResponse; private com.ets.model.Vehicle bike; private int id; public Bike() { jsonResponse = new JsonResponse("Bike"); } @Override public void prepare() throws Exception { if (id == 0) { bike = new com.ets.model.Bike(); } else { bike = bikeService.find(id); } } @Override public Object getModel() { return bike; } public void setId(int id) { this.id = id; } public void setBikeService(@Qualifier("bikeService") Service bikeService) { this.bikeService = bikeService; } public JsonResponse getJsonResponse() { return jsonResponse; } public String delete() { try { bike.setDeleted(new Date(System.currentTimeMillis())); bikeService.updateOrSave(bike); jsonResponse.addActionedId(id); jsonResponse.setAction("delete"); jsonResponse.setValid(true); } catch (Exception exception) { jsonResponse.setMessage(exception.toString()); } return "json"; } } Re-structured Actions providing incorrect response: public abstract class Vehicle extends ActionSupport implements ModelDriven { @Autowired protected Service bikeService; @Autowired protected Service carService; protected JsonResponse jsonResponse; protected com.ets.model.Vehicle vehicle; protected int id; protected abstract Service service(); @Override public Object getModel() { return bike; } public void setId(int id) { this.id = id; } public void setBikeService(@Qualifier("bikeService") Service bikeService) { this.bikeService = bikeService; } public void setCarService(@Qualifier("carService") Service carService) { this.carService = carService; } public JsonResponse getJsonResponse() { return jsonResponse; } public String delete() { try { vehicle.setDeleted(new Date(System.currentTimeMillis())); service().updateOrSave(vehicle); jsonResponse.addActionedId(id); jsonResponse.setAction("delete"); jsonResponse.setValid(true); } catch (Exception exception) { jsonResponse.setMessage(exception.toString()); } return "json"; } } public class Bike extends Vehicle implements Preparable { public Bike() { jsonResponse = new JsonResponse("Bike"); } @Override public void prepare() throws Exception { if (id == 0) { vehicle = new com.ets.model.Bike(); } else { vehicle = bikeService.find(id); } } @Override protected Service service() { return bikeService; } } public class Car extends Vehicle implements Preparable { public Car() { jsonResponse = new JsonResponse("Car"); } @Override public void prepare() throws Exception { if (id == 0) { vehicle = new com.ets.model.Car(); } else { vehicle = carService.find(id); } } @Override protected Service service() { return carService; } }

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