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• XNA CustomModelAnimationSample problem

  - by Mentoliptus

  I downloaded the official tutorial from:CustomModelAnimationSample It works fine but when I try to replicate it in my project, it fails to load the Tag property in my model. Is found that the probelm is in the line: skinnedModel = Content.Load<Model>("DudeWalk"); This line loads the model from the DudeWalk.fbx file and with the custom SkinnedModelProcessor. It loads the animations data in the model. After the line the Tag property is full. I stepped into the method and it went to the custom ModelData class. I copied everything from the projects CustomModelAnimationWindows and CustomModelAnimationPipeline to my solution and set all the references. I tried the same line of code and couldn't step in the method. It called the default method or model constructor and after the line the model's Tag propetry was null. I have to load the model through my custom SkinnedModelProcessor class, but how I tell the game to use this class? In the tutroail CustomModelClass the line is changed to: model = Content.Load<CustomModel>("tank"); So I assumed that I have to set the generic type to a custom model class, but the first example works without it. If anyone has some useful advice or some other helpful link, I'll be happy to try it.

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• Code contracts and inheritance

  - by DigiMortal

  In my last posting about code contracts I introduced you how to force code contracts to classes through interfaces. In this posting I will go step further and I will show you how code contracts work in the case of inherited classes. As a first thing let’s take a look at my interface and code contracts. [ContractClass(typeof(ProductContracts))] public interface IProduct {     int Id { get; set; }     string Name { get; set; }     decimal Weight { get; set; }     decimal Price { get; set; } }   [ContractClassFor(typeof(IProduct))] internal sealed class ProductContracts : IProduct {     private ProductContracts() { }       int IProduct.Id     {         get         {             return default(int);         }         set         {             Contract.Requires(value > 0);         }     }       string IProduct.Name     {         get         {             return default(string);         }         set         {             Contract.Requires(!string.IsNullOrWhiteSpace(value));             Contract.Requires(value.Length <= 25);         }     }       decimal IProduct.Weight     {         get         {             return default(decimal);         }         set         {             Contract.Requires(value > 3);             Contract.Requires(value < 100);         }     }       decimal IProduct.Price     {         get         {             return default(decimal);         }         set         {             Contract.Requires(value > 0);             Contract.Requires(value < 100);         }     } } And here is the product class that inherits IProduct interface. public class Product : IProduct {     public int Id { get; set; }     public string Name { get; set; }     public virtual decimal Weight { get; set; }     public decimal Price { get; set; } } if we run this code and violate the code contract set to Id we will get ContractException. public class Program {     static void Main(string[] args)     {         var product = new Product();         product.Id = -100;     } }   Now let’s make Product to be abstract class and let’s define new class called Food that adds one more contract to Weight property. public class Food : Product {     public override decimal Weight     {         get         {             return base.Weight;         }         set         {             Contract.Requires(value > 1);             Contract.Requires(value < 10);               base.Weight = value;         }     } } Now we should have the following rules at place for Food: weight must be greater than 1, weight must be greater than 3, weight must be less than 100, weight must be less than 10. Interesting part is what happens when we try to violate the lower and upper limits of Food weight. To see what happens let’s try to violate rules #2 and #4. Just comment one of the last lines out in the following method to test another assignment. public class Program {     static void Main(string[] args)     {         var food = new Food();         food.Weight = 12;         food.Weight = 2;     } } And here are the results as pictures to see where exceptions are thrown. Click on images to see them at original size. Violation of lower limit. Violation of upper limit. As you can see for both violations we get ContractException like expected. Code contracts inheritance is powerful and at same time dangerous feature. Although you can always narrow down the conditions that come from more general classes it is possible to define impossible or conflicting contracts at different points in inheritance hierarchy.

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• Pygame: Save a list of objects/classes/surfaces

  - by Sam Tubb

  I am working on a game, in which you can create mazes. You place blocks on a 16x16 grid, while choosing from a variety of block to make the level with. Whenever you create a block, it adds this class: class Block(object): def __init__(self,x,y,spr): self.x=x self.y=y self.sprite=spr self.rect=self.sprite.get_rect(x=self.x,y=self.y) to a list called instances. I tried shelving it to a .bin file, but it returns some error dealing with surfaces. How can I go about saving and loading levels? Any help is appreciated! :) Here is the whole code for reference: import pygame from pygame.locals import * #initstuff pygame.init() screen=pygame.display.set_mode((640,480)) pygame.display.set_caption('PiMaze') instances=[] #loadsprites menuspr=pygame.image.load('images/menu.png').convert() b1spr=pygame.image.load('images/b1.png').convert() b2spr=pygame.image.load('images/b2.png').convert() currentbspr=b1spr curspr=pygame.image.load('images/curs.png').convert() curspr.set_colorkey((0,255,0)) #menu menuspr.set_alpha(185) menurect=menuspr.get_rect(x=-260,y=4) class MenuItem(object): def __init__(self,pos,spr): self.x=pos[0] self.y=pos[1] self.sprite=spr self.pos=(self.x,self.y) self.rect=self.sprite.get_rect(x=self.x,y=self.y) class Block(object): def __init__(self,x,y,spr): self.x=x self.y=y self.sprite=spr self.rect=self.sprite.get_rect(x=self.x,y=self.y) while True: #menu items b1menu=b1spr.get_rect(x=menurect.left+32,y=48) b2menu=b2spr.get_rect(x=menurect.left+64,y=48) menuitems=[MenuItem(b1menu,b1spr),MenuItem(b2menu,b2spr)] screen.fill((20,30,85)) mse=pygame.mouse.get_pos() key=pygame.key.get_pressed() placepos=((mse[0]/16)*16,(mse[1]/16)*16) if key[K_q]: if mse[0]<260: if menurect.right<255: menurect.right+=1 else: if menurect.left>-260: menurect.left-=1 else: if menurect.left>-260: menurect.left-=1 for e in pygame.event.get(): if e.type==QUIT: exit() if menurect.right<100: if e.type==MOUSEBUTTONUP: if e.button==1: to_remove = [i for i in instances if i.rect.collidepoint(placepos)] for i in to_remove: instances.remove(i) if not to_remove: instances.append(Block(placepos[0],placepos[1],currentbspr)) for i in instances: screen.blit(i.sprite,i.rect) if not key[K_q]: screen.blit(curspr,placepos) screen.blit(menuspr,menurect) for item in menuitems: screen.blit(item.sprite,item.pos) if item.rect.collidepoint(mse): if pygame.mouse.get_pressed()==(1,0,0): currentbspr=item.sprite pygame.draw.rect(screen, ((255,0,0)), item, 1) pygame.display.flip()

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• Better solution then simple factory method when concrete implementations have different attributes

  - by danip

  abstract class Animal { function eat() {..} function sleep() {..} function isSmart() } class Dog extends Animal { public $blnCanBark; function isSmart() { return $this->blnCanBark; } } class Cat extends Animal { public $blnCanJumpHigh; function isSmart() { return $this->blnCanJumpHigh; } } .. and so on up to 10-20 animals. Now I created a factory using simple factory method and try to create instances like this: class AnimalFactory { public static function create($strName) { switch($strName) { case 'Dog': return new Dog(); case 'Cat': return new Cat(); default: break; } } } The problem is I can't set the specific attributes like blnCanBark, blnCanJumpHigh in an efficient way. I can send all of them as extra params to create but this will not scale to more then a few classes. Also I can't break the inheritance because a lot of the basic functionality is the same. Is there a better pattern to solve this?

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• Sprites, Primitives and logic entity as structs

  - by Jeffrey

  I'm wondering would it be considered acceptable: The window class is responsible for drawing data, so it will have a method: Window::draw(const Sprite&); Window::draw(const Rect&); Window::draw(const Triangle&); Window::draw(const Circle&); and all those primitives + sprites would be just public struct. For example Sprite: struct Sprite { float x, y; // center float origin_x, origin_y; float width, height; float rotation; float scaling; GLuint texture; Sprite(float w, float h); Sprite(float w, float h, float a, float b); void useTexture(std::string file); void setOrigin(float a, float b); void move(float a, float b); // relative move void moveTo(float a, float b); // absolute move void rotate(float a); // relative rotation void rotateTo(float a); // absolute rotation void rotationReset(); void scale(float a); // relative scaling void scaleTo(float a); // absolute scaling void scaleReset(); }; So instead of having each primitive to call their draw() function, which is a little bit off topic for their object, I let the Window class handle all the OpenGL stuff and manipulate them as simple objects that will be drawn later on. Is this pattern used? Does it have any cons against it's primitives-draw-themself pattern? Are there any other related patterns?

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• State Design Pattern .NET Code Sample

  using System;using System.Collections.Generic;using System.Linq;using System.Text;class Program{ static void Main(string[] args) { Person p1 = new Person("P1"); Person p2 = new Person("P2"); p1.EatFood(); p2.EatFood(); p1.Vomit(); p2.Vomit(); }}interface StomachState{ void Eat(Person p); void Vomit(Person p);}class StomachFull : StomachState{ public void Eat(Person p) { Console.WriteLine("Can't eat more."); } public void Vomit(Person p) { Console.WriteLine("I've just Vomited."); p.StomachState = new StomachEmpty(); }}class StomachEmpty : StomachState{ public void Eat(Person p) { Console.WriteLine("I've just had food."); p.StomachState = new StomachFull(); } public void Vomit(Person p) { Console.WriteLine("Nothing to Vomit."); }}class Person{ private StomachState stomachState; private String personName; public Person(String personName) { this.personName = personName; StomachState = new StomachEmpty(); } public StomachState StomachState { get { return stomachState; } set { stomachState = value; Console.WriteLine(personName + " Stomach State Changed to " + StomachState.GetType().Name); Console.WriteLine("***********************************************\n"); } } public Person(StomachState StomachState) { this.StomachState = StomachState; } public void EatFood() { StomachState.Eat(this); } public void Vomit() { StomachState.Vomit(this); }} span.fullpost {display:none;}

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• How can I resolve component types in a way that supports adding new types relatively easily?

  - by John

  I am trying to build an Entity Component System for an interactive application developed using C++ and OpenGL. My question is quite simple. In my GameObject class I have a collection of Components. I can add and retrieve components. class GameObject: public Object { public: GameObject(std::string objectName); ~GameObject(void); Component * AddComponent(std::string name); Component * AddComponent(Component componentType); Component * GetComponent (std::string TypeName); Component * GetComponent (<Component Type Here>); private: std::map<std::string,Component*> m_components; }; I will have a collection of components that inherit from the base Components class. So if I have a meshRenderer component and would like to do the following GameObject * warship = new GameObject("myLovelyWarship"); MeshRenderer * meshRenderer = warship->AddComponent(MeshRenderer); or possibly MeshRenderer * meshRenderer = warship->AddComponent("MeshRenderer"); I could be make a Component Factory like this: class ComponentFactory { public: static Component * CreateComponent(const std::string &compTyp) { if(compTyp == "MeshRenderer") return new MeshRenderer; if(compTyp == "Collider") return new Collider; return NULL; } }; However, I feel like I should not have to keep updating the Component Factory every time I want to create a new custom Component but it is an option. Is there a more proper way to add and retrieve these components? Is standard templates another solution?

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• How do you encode Algebraic Data Types in a C#- or Java-like language?

  - by Jörg W Mittag

  There are some problems which are easily solved by Algebraic Data Types, for example a List type can be very succinctly expressed as: data ConsList a = Empty | ConsCell a (ConsList a) consmap f Empty = Empty consmap f (ConsCell a b) = ConsCell (f a) (consmap f b) l = ConsCell 1 (ConsCell 2 (ConsCell 3 Empty)) consmap (+1) l This particular example is in Haskell, but it would be similar in other languages with native support for Algebraic Data Types. It turns out that there is an obvious mapping to OO-style subtyping: the datatype becomes an abstract base class and every data constructor becomes a concrete subclass. Here's an example in Scala: sealed abstract class ConsList[+T] { def map[U](f: T => U): ConsList[U] } object Empty extends ConsList[Nothing] { override def map[U](f: Nothing => U) = this } final class ConsCell[T](first: T, rest: ConsList[T]) extends ConsList[T] { override def map[U](f: T => U) = new ConsCell(f(first), rest.map(f)) } val l = (new ConsCell(1, new ConsCell(2, new ConsCell(3, Empty))) l.map(1+) The only thing needed beyond naive subclassing is a way to seal classes, i.e. a way to make it impossible to add subclasses to a hierarchy. How would you approach this problem in a language like C# or Java? The two stumbling blocks I found when trying to use Algebraic Data Types in C# were: I couldn't figure out what the bottom type is called in C# (i.e. I couldn't figure out what to put into class Empty : ConsList< ??? >) I couldn't figure out a way to seal ConsList so that no subclasses can be added to the hierarchy What would be the most idiomatic way to implement Algebraic Data Types in C# and/or Java? Or, if it isn't possible, what would be the idiomatic replacement?

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• How to automatically render all opaque meshes with a specific shader?

  - by dsilva.vinicius

  I have a specular outline shader that I want to be used on all opaque meshes of the scene whenever a specific camera renders. The shader is working properly when it is manually applied to some material. The shader is as follows: Shader "Custom/Outline" { Properties { _Color ("Main Color", Color) = (.5,.5,.5,1) _OutlineColor ("Outline Color", Color) = (1,0.5,0,1) _Outline ("Outline width", Range (0.0, 0.1)) = .05 _SpecColor ("Specular Color", Color) = (0.5, 0.5, 0.5, 1) _Shininess ("Shininess", Range (0.03, 1)) = 0.078125 _MainTex ("Base (RGB) Gloss (A)", 2D) = "white" {} } SubShader { Tags { "Queue"="Overlay" "RenderType"="Opaque" } Pass { Name "OUTLINE" Tags { "LightMode" = "Always" } Cull Off ZWrite Off // Uncomment to show outline always. //ZTest Always CGPROGRAM #pragma target 3.0 #pragma vertex vert #pragma fragment frag #include "UnityCG.cginc" struct appdata { float4 vertex : POSITION; float3 normal : NORMAL; }; struct v2f { float4 pos : POSITION; float4 color : COLOR; }; float _Outline; float4 _OutlineColor; v2f vert(appdata v) { // just make a copy of incoming vertex data but scaled according to normal direction v2f o; o.pos = mul(UNITY_MATRIX_MVP, v.vertex); float3 norm = mul ((float3x3)UNITY_MATRIX_IT_MV, v.normal); float2 offset = TransformViewToProjection(norm.xy); o.pos.xy += offset * o.pos.z * _Outline; o.color = _OutlineColor; return o; } float4 frag(v2f fromVert) : COLOR { return fromVert.color; } ENDCG } UsePass "Specular/FORWARD" } FallBack "Specular" } The camera used fot the effect has just a script component which setups the shader replacement: using UnityEngine; using System.Collections; public class DetectiveEffect : MonoBehaviour { public Shader EffectShader; // Use this for initialization void Start () { this.camera.SetReplacementShader(EffectShader, "RenderType=Opaque"); } // Update is called once per frame void Update () { } } Unfortunately, whenever I use this camera I just see the background color. Any ideas?

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• Farseer tutorial for the absolute beginners

  - by Bil Simser

  This post is inspired (and somewhat a direct copy) of a couple of posts Emanuele Feronato wrote back in 2009 about Box2D (his tutorial was ActionScript 3 based for Box2D, this is C# XNA for the Farseer Physics Engine). Here’s what we’re building: What is Farseer The Farseer Physics Engine is a collision detection system with realistic physics responses to help you easily create simple hobby games or complex simulation systems. Farseer was built as a .NET version of Box2D (based on the Box2D.XNA port of Box2D). While the constructs and syntax has changed over the years, the principles remain the same. This tutorial will walk you through exactly what Emanuele create for Flash but we’ll be doing it using C#, XNA and the Windows Phone platform. The first step is to download the library from its home on CodePlex. If you have NuGet installed, you can install the library itself using the NuGet package that but we’ll also be using some code from the Samples source that can only be obtained by downloading the library. Once you download and unpacked the zip file into a folder and open the solution, this is what you will get: The Samples XNA WP7 project (and content) have all the demos for Farseer. There’s a wealth of info here and great examples to look at to learn. The Farseer Physics XNA WP7 project contains the core libraries that do all the work. DebugView XNA contains an XNA-ready class to let you view debug data and information in the game draw loop (which you can copy into your project or build the source and reference the assembly). The downloaded version has to be compiled as it’s only available in source format so you can do that now if you want (open the solution file and rebuild everything). If you’re using the NuGet package you can just install that. We only need the core library and we’ll be copying in some code from the samples later. Your first Farseer experiment Start Visual Studio and create a new project using the Windows Phone template can call it whatever you want. It’s time to edit Game1.cs 1 public class Game1 : Game 2 { 3 private readonly GraphicsDeviceManager _graphics; 4 private DebugViewXNA _debugView; 5 private Body _floor; 6 private SpriteBatch _spriteBatch; 7 private float _timer; 8 private World _world; 9 10 public Game1() 11 { 12 _graphics = new GraphicsDeviceManager(this) 13 { 14 PreferredBackBufferHeight = 800, 15 PreferredBackBufferWidth = 480, 16 IsFullScreen = true 17 }; 18 19 Content.RootDirectory = "Content"; 20 21 // Frame rate is 30 fps by default for Windows Phone. 22 TargetElapsedTime = TimeSpan.FromTicks(333333); 23 24 // Extend battery life under lock. 25 InactiveSleepTime = TimeSpan.FromSeconds(1); 26 } 27 28 protected override void LoadContent() 29 { 30 // Create a new SpriteBatch, which can be used to draw textures. 31 _spriteBatch = new SpriteBatch(_graphics.GraphicsDevice); 32 33 // Load our font (DebugViewXNA needs it for the DebugPanel) 34 Content.Load<SpriteFont>("font"); 35 36 // Create our World with a gravity of 10 vertical units 37 if (_world == null) 38 { 39 _world = new World(Vector2.UnitY*10); 40 } 41 else 42 { 43 _world.Clear(); 44 } 45 46 if (_debugView == null) 47 { 48 _debugView = new DebugViewXNA(_world); 49 50 // default is shape, controller, joints 51 // we just want shapes to display 52 _debugView.RemoveFlags(DebugViewFlags.Controllers); 53 _debugView.RemoveFlags(DebugViewFlags.Joint); 54 55 _debugView.LoadContent(GraphicsDevice, Content); 56 } 57 58 // Create and position our floor 59 _floor = BodyFactory.CreateRectangle( 60 _world, 61 ConvertUnits.ToSimUnits(480), 62 ConvertUnits.ToSimUnits(50), 63 10f); 64 _floor.Position = ConvertUnits.ToSimUnits(240, 775); 65 _floor.IsStatic = true; 66 _floor.Restitution = 0.2f; 67 _floor.Friction = 0.2f; 68 } 69 70 protected override void Update(GameTime gameTime) 71 { 72 // Allows the game to exit 73 if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed) 74 Exit(); 75 76 // Create a random box every second 77 _timer += (float) gameTime.ElapsedGameTime.TotalSeconds; 78 if (_timer >= 1.0f) 79 { 80 // Reset our timer 81 _timer = 0f; 82 83 // Determine a random size for each box 84 var random = new Random(); 85 var width = random.Next(20, 100); 86 var height = random.Next(20, 100); 87 88 // Create it and store the size in the user data 89 var box = BodyFactory.CreateRectangle( 90 _world, 91 ConvertUnits.ToSimUnits(width), 92 ConvertUnits.ToSimUnits(height), 93 10f, 94 new Point(width, height)); 95 96 box.BodyType = BodyType.Dynamic; 97 box.Restitution = 0.2f; 98 box.Friction = 0.2f; 99 100 // Randomly pick a location along the top to drop it from 101 box.Position = ConvertUnits.ToSimUnits(random.Next(50, 400), 0); 102 } 103 104 // Advance all the elements in the world 105 _world.Step(Math.Min((float) gameTime.ElapsedGameTime.TotalMilliseconds*0.001f, (1f/30f))); 106 107 // Clean up any boxes that have fallen offscreen 108 foreach (var box in from box in _world.BodyList 109 let pos = ConvertUnits.ToDisplayUnits(box.Position) 110 where pos.Y > _graphics.GraphicsDevice.Viewport.Height 111 select box) 112 { 113 _world.RemoveBody(box); 114 } 115 116 base.Update(gameTime); 117 } 118 119 protected override void Draw(GameTime gameTime) 120 { 121 GraphicsDevice.Clear(Color.FromNonPremultiplied(51, 51, 51, 255)); 122 123 _spriteBatch.Begin(); 124 125 var projection = Matrix.CreateOrthographicOffCenter( 126 0f, 127 ConvertUnits.ToSimUnits(_graphics.GraphicsDevice.Viewport.Width), 128 ConvertUnits.ToSimUnits(_graphics.GraphicsDevice.Viewport.Height), 0f, 0f, 129 1f); 130 _debugView.RenderDebugData(ref projection); 131 132 _spriteBatch.End(); 133 134 base.Draw(gameTime); 135 } 136 } 137 Lines 4: Declare the debug view we’ll use for rendering (more on that later). Lines 8: Declare _world variable of type class World. World is the main object to interact with the Farseer engine. It stores all the joints and bodies, and is responsible for stepping through the simulation. Lines 12-17: Create the graphics device we’ll be rendering on. This is an XNA component and we’re just setting it to be the same size as the phone and toggling it to be full screen (no system tray). Lines 34: We create a SpriteFont here by adding it to the project. It’s called “font” because that’s what the DebugView uses but you can name it whatever you want (and if you’re not using DebugView for your production app you might have several fonts). Lines 37-44: We create the physics environment that Farseer uses to contain all the objects by specifying it here. We’re using Vector2.UnitY*10 to represent the gravity to be used in the environment. In other words, 10 units going in a downward motion. Lines 46-56: We create the DebugViewXNA here. This is copied from the […] from the code you downloaded and provides the ability to render all entities onto the screen. In a production release you’ll be doing the rendering yourself of each object but we cheat a bit for the demo and let the DebugView do it for us. The other thing it can provide is to render out a panel of debugging information while the simulation is going on. This is useful in tracking down objects, figuring out how something works, or just keeping track of what’s in the engine. Lines 49-67: Here we create a rigid body (Farseer only supports rigid bodies) to represent the floor that we’ll drop objects onto. We create it by using one of the Farseer factories and specifying the width and height. The ConvertUnits class is copied from the samples code as-is and lets us toggle between display units (pixels) and simulation units (usually metres). We’re creating a floor that’s 480 pixels wide and 50 pixels high (converting them to SimUnits for the engine to understand). We also position it near the bottom of the screen. Values are in metres and when specifying values they refer to the centre of the body object. Lines 77-78: The game Update method fires 30 times a second, too fast to be creating objects this quickly. So we use a variable to track the elapsed seconds since the last update, accumulate that value, then create a new box to drop when 1 second has passed. Lines 89-94: We create a box the same way we created our floor (coming up with a random width and height for the box). Lines 96-101: We set the box to be Dynamic (rather than Static like the floor object) and position it somewhere along the top of the screen. And now you created the world. Gravity does the rest and the boxes fall to the ground. Here’s the result: Farseer Physics Engine Demo using XNA Lines 105: We must update the world at every frame. We do this with the Step method which takes in the time interval. [more] Lines 108-114: Body objects are added to the world but never automatically removed (because Farseer doesn’t know about the display world, it has no idea if an item is on the screen or not). Here we just loop through all the entities and anything that’s dropped off the screen (below the bottom) gets removed from the World. This keeps our entity count down (the simulation never has more than 30 or 40 objects in the world no matter how long you run it for). Too many entities and the app will grind to a halt. Lines 125-130: Farseer knows nothing about the UI so that’s entirely up to you as to how to draw things. Farseer is just tracking the objects and moving them around using the physics engine and it’s rules. You’ll still use XNA to draw items (using the SpriteBatch.Draw method) so you can load up your usual textures and draw items and pirates and dancing zombies all over the screen. Instead in this demo we’re going to cheat a little. In the sample code for Farseer you can download there’s a project called DebugView XNA. This project contains the DebugViewXNA class which just handles iterating through all the bodies in the world and drawing the shapes. So we call the RenderDebugData method here of that class to draw everything correctly. In the case of this demo, we just want to draw Shapes so take a look at the source code for the DebugViewXNA class as to how it extracts all the vertices for the shapes created (in this case simple boxes) and draws them. You’ll learn a *lot* about how Farseer works just by looking at this class. That’s it, that’s all. Simple huh? Hope you enjoy the code and library. Physics is hard and requires some math skills to really grok. The Farseer Physics Engine makes it pretty easy to get up and running and start building games. In future posts we’ll get more in-depth with things you can do with the engine so this is just the beginning. Enjoy!

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• Design for object with optional and modifiable attributtes?

  - by Ikuzen

  I've been using the Builder pattern to create objects with a large number of attributes, where most of them are optional. But up until now, I've defined them as final, as recommended by Joshua Block and other authors, and haven't needed to change their values. I am wondering what should I do though if I need a class with a substantial number of optional but non-final (mutable) attributes? My Builder pattern code looks like this: public class Example { //All possible parameters (optional or not) private final int param1; private final int param2; //Builder class public static class Builder { private final int param1; //Required parameters private int param2 = 0; //Optional parameters - initialized to default //Builder constructor public Builder (int param1) { this.param1 = param1; } //Setter-like methods for optional parameters public Builder param2(int value) { param2 = value; return this; } //build() method public Example build() { return new Example(this); } } //Private constructor private Example(Builder builder) { param1 = builder.param1; param2 = builder.param2; } } Can I just remove the final keyword from the declaration to be able to access the attributes externally (through normal setters, for example)? Or is there a creational pattern that allows optional but non-final attributes that would be better suited in this case?

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• How can I making Twitter, Facebook and Reddit share buttons load last?

  - by Daniel Bingham

  I have a website with a number of pages that sport twitter, facebook and reddit share buttons. They take forever to load and until they do the rest of the page doesn't load. So how I can make them load last? Currently, they are loaded something like this: <div class="item"><a href="http://twitter.com/share" class="twitter-share-button" data-count="vertical" data-via="FridgeToFood" data-related="danielBingham:Recipe and update tweets from Fridge to Food.">Tweet</a><script type="text/javascript" src="http://platform.twitter.com/widgets.js"></script></div> <div class="item"><script src="http://connect.facebook.net/en_US/all.js#xfbml=1"></script><fb:like layout="box_count" width="40"></fb:like></div> <div class="item"> <script type="text/javascript">reddit_target='recipes';</script> <script type="text/javascript" src="http://reddit.com/static/button/button2.js"></script> </div> They are in a div called "shareWrapper" and are loading to one side of the page. The buttons load where ever the script code is placed. As far as I know, I can't place the script code at the bottom of the page and move the resulting buttons after the fact. I want them to appear near the top, which right now means they are stopping everything below them from loading for several seconds. I tried loading them using javascript, but using JQuery's $(document).ready(), but that failed. It seems to leave the page in some sort of loading loop from which it never emerges. Are there other ways to get these to load last?

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• An ideal way to decode JSON documents in C?

  - by AzizAG

  Assuming I have an API to consume that uses JSON as a data transmission method, what is an ideal way to decode the JSON returned by each API resource? For example, in Java I'd create a class for each API resource then initiate an object of that class and consume data from it. for example: class UserJson extends JsonParser { public function UserJson(String document) { /*Initial document parsing goes here...*/ } //A bunch of getter methods . . . . } The probably do something like this: UserJson userJson = new UserJson(jsonString);//Initial parsing goes in the constructor String username = userJson.getName();//Parse JSON name property then return it as a String. Or when using a programming language with associative arrays(i.e., hash table) the decoding process doesn't require creating a class: (PHP) $userJson = json_decode($jsonString);//Decode JSON as key=>value $username = $userJson['name']; But, when I'm programming in procedural programming languages (C), I can't go with either method, since C is neither OOP nor supports associative arrays(by default, at least). What is the "correct" method of parsing pre-defined JSON strings(i.e., JSON documents specified by the API provider via examples or documentation)? The method I'm currently using is creating a file for each API resource to parse, the problem with this method is that it's basically a lousy version of the OOP method, as it looks exactly like the OOP method but doesn't provide any OOP benefits(e.g., can't pass an object of the parser, etc.). I've been thinking about encapsulating each API resource parser file in a publicly accessed structure(pointing all functions/publicly usable variables to the structure) then accessing the parser file code from within the structure(parser.parse(), parser.getName(), etc.). As this way looks a bit better than the my current method, it still just a rip off the OOP way, isn't it? Any suggestions for methods to parse JSON documents on procedural programming lanauges? Any comments on the methods I'm currently using(either 3 of them)?

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• Is there a better way to consume an ASP.NET Web API call in an MVC controller?

  - by davidisawesome

  In a new project I am creating for my work I am creating a fairly large ASP.NET Web API. The api will be in a separate visual studio solution that also contains all of my business logic and database interactions, Model classes as well. In the test application I am creating (which is asp.net mvc4), I want to be able to hit an api url I defined from the control and cast the return JSON to a Model class. The reason behind this is that I want to take advantage of strongly typing my views to a Model. This is all still in a proof of concept stage, so I have not done any performance testing on it, but I am curious if what I am doing is a good practice, or if I am crazy for even going down this route. Here is the code on the client controller: public class HomeController : Controller { protected string dashboardUrlBase = "http://localhost/webapi/api/StudentDashboard/"; public ActionResult Index() //This view is strongly typed against User { //testing against Joe Bob string adSAMName = "jBob"; WebClient client = new WebClient(); string url = dashboardUrlBase + "GetUserRecord?userName=" + adSAMName; //'User' is a Model class that I have defined. User result = JsonConvert.DeserializeObject<User>(client.DownloadString(url)); return View(result); } . . . } If I choose to go this route another thing to note is I am loading several partial views in this page (as I will also do in subsequent pages). The partial views are loaded via an $.ajax call that hits this controller and does basically the same thing as the code above: Instantiate a new WebClient Define the Url to hit Deserialize the result and cast it to a Model Class. So it is possible (and likely) I could be performing the same actions 4-5 times for a single page. Is there a better method to do this that will: Let me keep strongly typed views. Do my work on the server rather than on the client (this is just a preference since I can write C# faster than I can write javascript).

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• Everything has an Interface [closed]

  - by Shane

  Possible Duplicate: Do I need to use an interface when only one class will ever implement it? I am taking over a project where every single real class is implementing an Interface. The vast majority of these interfaces are implemented by a single class that share a similar name and the exact same methods (ex: MyCar and MyCarImpl). Almost no 2 classes in the project implement more than the interface that shares its name. I know the general recommendation is to code to an interface rather than an implementation, but isn't this taking it a bit too far? The system might be more flexible in that it is easier to add a new class that behaves very much like an existing class. However, it is significantly harder to parse through the code and method changes now require 2 edits instead of 1. Personally, I normally only create interfaces when there is a need for multiple classes to have the same behavior. I subscribe to YAGNI, so I don't create something unless I see a real need for it. Am I doing it all wrong or is this project going way overboard?

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• What is an effective way to convert a shared memory-mapped system to another data access model?

  - by Rob Jones

  I have a code base that is designed around shared memory. Each process that needs to access the memory maps it into its own address space. The data structures in the shared memory are directly accessed, that is, there is no API. For example: Assume the following: typedef struct { int x; int y; struct { int a; int b; } z; } myStruct; myStruct s; Then a process might access this structure as: myStruct *s = mapGlobalMem(); And use it as: int tmpX = s->x; The majority of the information in the global structure is configuration information that is set once and read many times. I would like to store this information in a database and develop an API to access the database. The problem is, these references are sprinkled throughout the code. I need a way to parse the code and identify global structure references that will need to be refactored. I've looked into using ANTLR to create a parser that will identify references to a small set of structures and enter them into a custom symbol table. I could then use this symbol table to identify which source files need to be refactored. It looks like a promising approach. What other approaches are there? Of course, I'm looking for a programmatic approach. There are far too many source files to examine each one visually. This is all ordinary ANSI C. Nothing else.

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• Seeking for a better solution to restrict access in GRUB2 menu

  - by LiveWireBT

  I just read that in certain situations you should also protect access to your GRUB2 menu by setting a password and may be refining acces by adding --unrestricted or --users as arguments to menuentries und submenus. I read the corresponding pages in the Ubuntu Community Documentation and the Arch Wiki. So, I created /etc/grub.d/01_security, stored usernames and passwords in there, made the file executable and ran update-grub. This is working as intended, every action in the menu prompts for username and password, but I also want to modify the automatically generated entries to either restrict them to certain users (via --users) or make them available for everyone, but not editable by everyone (via --unrestricted). I was able to find the proper lines in 10_linux and edit them accordingly, however I'd love to see an easier solution. Perhaps an option like GRUB_DISABLE_RECOVERY="true" or GRUB_DISABLE_OS_PROBER=true in /etc/default/grub for easy (re)configuration (for linux and os-prober generated entries). Here's a diff from my 13.10 installation: $ diff /etc/grub.d/10_linux /etc/grub.d/10_linux_bak 123c123 < echo "menuentry '$(echo "$title" | grub_quote)' ${CLASS} --unrestriced \$menuentry_id_option 'gnulinux-$version-$type-$boot_device_id' {" | sed "s/^$ --- > echo "menuentry '$(echo "$title" | grub_quote)' ${CLASS} \$menuentry_id_option 'gnulinux-$version-$type-$boot_device_id' {" | sed "s/^/$submenu_inde$ 125c125 < echo "menuentry '$(echo "$os" | grub_quote)' ${CLASS} --unrestricted \$menuentry_id_option 'gnulinux-simple-$boot_device_id' {" | sed "s/^/$submenu_$ --- > echo "menuentry '$(echo "$os" | grub_quote)' ${CLASS} \$menuentry_id_option 'gnulinux-simple-$boot_device_id' {" | sed "s/^/$submenu_indentation/" 323c323 < echo "submenu --unrestricted '$(gettext_printf "Advanced options for %s" "${OS}" | grub_quote)' \$menuentry_id_option 'gnulinux-advanced-$boot_device_$ --- > echo "submenu '$(gettext_printf "Advanced options for %s" "${OS}" | grub_quote)' \$menuentry_id_option 'gnulinux-advanced-$boot_device_id' {" tl;dr: I'd love the see a simple solution for GRUB2 entries that cannot be modified without a password or are limited to certain users. (Yes, GRUB_DISABLE_RECOVERY="true" is active.)

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• Ninject/DI: How to correctly pass initialisation data to injected type at runtime

  - by MrLane

  I have the following two classes: public class StoreService : IStoreService { private IEmailService _emailService; public StoreService(IEmailService emailService) { _emailService = emailService; } } public class EmailService : IEmailService { } Using Ninject I can set up bindings no problem to get it to inject a concrete implementation of IEmailService into the StoreService constructor. StoreService is actually injected into the code behind of an ASP.NET WebForm as so: [Ninject.Inject] public IStoreService StoreService { get; set; } But now I need to change EmailService to accept an object that contains SMTP related settings (that are pulled from the ApplicationSettings of the Web.config). So I changed EmailService to now look like this: public class EmailService : IEmailService { private SMTPSettings _smtpSettings; public void SetSMTPSettings(SMTPSettings smtpSettings) { _smtpSettings = smtpSettings; } } Setting SMTPSettings in this way also requires it to be passed into StoreService (via another public method). This has to be done in the Page_Load method in the WebForms code behind (I only have access to the Settings class in the UI layer). With manual/poor mans DI I could pass SMTPSettings directly into the constructor of EmailService and then inject EmailService into the StoreService constructor. With Ninject I don't have access to the instances of injected types outside of the objects they are injected to, so I have to set their data AFTER Ninject has already injected them via a separate public setter method. This to me seems wrong. How should I really be solving this scenario?

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• How to deal with data on the model specific to the technology being used?

  - by user1620696

  There are some cases where some of the data on a class of the domain model of an application seems to be dependent on the technology being used. One example of this is the following: suppose we are building one application in .NET such that there's the need of an Employee class. Suppose further that we are going to implement relational database, then the Employee has a primary key right? So that the classe would be something like public class Employee { public int EmployeeID { get; set; } public string Name { get; set; } ... } Now, that EmployeeID is dependent on the technology right? That's something that has to do with the way we've choose to persist our data. Should we write down a class independent of such things? If we do it this way, how should we work? I think I would need to map all the time between domain model and persistence specific types, but I'm not sure.

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• How do I parse a header with two different version [ID3] avoiding code duplication?

  - by user66141

  I really hope you can give me some interesting viewpoints for my situation, because I am not satisfied with my current approach. I am writing an MP3 parser, starting with an ID3v2 parser. Right now I`m working on the extended header parsing, my issue is that the optional header is defined differently in version 2.3 and 2.4 of the tag. The 2.3 version optional header is defined as follows: struct ID3_3_EXTENDED_HEADER{ DWORD dwExtHeaderSize; //Extended header size (either 6 or 8 bytes , excluded) WORD wExtFlags; //Extended header flags DWORD dwSizeOfPadding; //Size of padding (size of the tag excluding the frames and headers) }; While the 2.4 version is defined : struct ID3_4_EXTENDED_HEADER{ DWORD dwExtHeaderSize; //Extended header size (synchsafe int) BYTE bNumberOfFlagBytes; //Number of flag bytes BYTE bFlags; //Flags }; How could I parse the header while minimizing code duplication? Using two different functions to parse each version sounds less great, using a single function with a different flow for each occasion is similar, any good practices for this kind of issues ? Any tips for avoiding code duplication? Any help would be appreciated.

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• Why is my shadowmap all white?

  - by Berend

  I was trying out a shadowmap. But all my shadow is white. I think there is some problem with my homogeneous component. Can anybody help me? The rest of my code is written in xna Here is the hlsl code I used float4x4 xWorld; float4x4 xView; float4x4 xProjection; struct VertexToPixel { float4 Position : POSITION; float4 ScreenPos : TEXCOORD1; float Depth : TEXCOORD2; }; struct PixelToFrame { float4 Color : COLOR0; }; //------- Technique: ShadowMap -------- VertexToPixel MyVertexShader(float4 inPos: POSITION0, float3 inNormal: NORMAL0) { VertexToPixel Output = (VertexToPixel)0; float4x4 preViewProjection = mul(xView, xProjection); float4x4 preWorldViewProjection = mul(xWorld, preViewProjection); Output.Position =mul(inPos, mul(xWorld, preViewProjection)); Output.Depth = Output.Position.z / Output.Position.w; Output.ScreenPos = Output.Position; return Output; } float4 MyPixelShader(VertexToPixel PSIn) : COLOR0 { PixelToFrame Output = (PixelToFrame)0; Output.Color = PSIn.ScreenPos.z/PSIn.ScreenPos.w; return Output.Color; } technique ShadowMap { pass Pass0 { VertexShader = compile vs_2_0 MyVertexShader(); PixelShader = compile ps_2_0 MyPixelShader(); } }

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• How can I pass an external instance to the constructor of an object that's being created using the default XNA XML content loader?

  - by Michael

  I'm trying to understand how to use the XNA XML content importer to instantiate non-trivial objects that are more than a collection of basic properties (e.g., a class that inherits from DrawableGameObject or GameObject and requires other things to be passed into its constructor). Is it possible to pass existing external instances (e.g., an instance of the current Game) to the constructor of an object that's being created using the default XNA XML content loader? For example, imagine that I have the following class, inheriting from DrawableGameComponent: public class Character : DrawableGameComponent { public string Name { get; set; } public Character(Game game) : base(game) { } public override void Update(GameTime gameTime) { } public override void Draw(GameTime gameTime) { } } If I had a simple class that did not need other parameters in its constructor (i.e., the Game instance), then I could simply use this XML: <XnaContent> <Asset Type="MyNamespace.Character"> <Name>John Doe</Name> </Asset> </XnaContent> ...and then create an instance of Character using this code: var character = Content.Load<Character>("MyXmlAssetName"); But that won't work because I need to pass the need to pass the Game into the constructor. What's the best way to handle this situation? Is there a way to pass in things like the current Game using the default XNA XML content loader? Do I need to write my own XML loader? (If so, how?) Is there a better object-oriented design that I should be using for my classes? Note: Although I used Game in this example, I'm really just asking how to pass any type of existing instance to my constructors. (For example, I'm using the Farseer Physics Engine, and some of my classes also need a reference to the Farseer World object too.) Thanks in advance.

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• What is the best approach to solve a factory method problem which has to be an instance?

  - by Iago

  I have to add new funcionality in a web service legacy project and I'm thinking what is the best approach for a concrete situation. The web service is simple: It receives a XML file, unmarshalling, generates response's objects, marshalling and finally it sends the response as a XML file. For every XML files received, the web service always responds with the same XML structure. What I have to do is to generate a different XML file according to the XML received. So I have a controller class which has all marshalling/unmarshalling operations, but this controller class has to be an instance. Depending on XML received I need some marshalling methods or others. Trying to make few changes on legacy source, what is the best approach? My first approach was to do a factory method pattern with the controller class, but this class has to be an instance. I want to keep, as far as it goes, this structure: classController.doMarshalling(); I think this one is a bit smelly: if(XMLReceived.isTypeOne()) classController.doMarshallingOne(); else if(XMLReceived.isTypeTwo()) classController.doMarshallingTwo(); else if(XMLReceived.isTypeThree()) classController.doMarshallingThree(); else if ... I hope my question is well understood

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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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• Code Clone Analysis on Rawr &ndash; Part 1

  - by Dylan Smith

  In this post we’ll take a look at the first result from the Code Clone Analysis, and do some refactoring to eliminate the duplication.  The first result indicated that it found an exact match repeated 14 times across the solution, with 18 lines of duplicated code in each of the 14 blocks.   Net Lines Of Code Deleted: 179     In this case the code in question was a bunch of classes representing the various Bosses.  Every Boss class has a constructor that initializes a whole bunch of properties of that boss, however, for most bosses a lot of these are simply set to 0’s.     Every Boss class inherits from the class MultiDiffBoss, so I simply moved all the initialization of the various properties to the base class constructor, and left it up to the Boss subclasses to only set those that are different than the default values. In this case there are actually 22 Boss subclasses, however, due to some inconsistencies in the code structure Code Clone only identified 14 of them as identical blocks.  Since I was in there refactoring the 14 identified already, it was pretty straightforward to identify the other 8 subclasses that had the same duplicated behavior and refactor those also.   Note: Code Clone Analysis is pretty slow right now.  It takes approx 1 min to build this solution, but it takes 9 mins to run Code Clone Analysis.  Personally, if the results are high quality I’m OK with it taking a long time to run since I don’t expect it’s something I would be running all that often.  However, it would be nice to be able to run it as part of a nightly build, but at this time I don’t believe it’s possible to run outside of Visual Studio due to a dependency on the meta-data available in the VS environment.

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