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• The Great Divorce

  - by BlackRabbitCoder

  I have a confession to make: I've been in an abusive relationship for more than 17 years now.  Yes, I am not ashamed to admit it, but I'm finally doing something about it. I met her in college, she was new and sexy and amazingly fast -- and I'd never met anything like her before.  Her style and her power captivated me and I couldn't wait to learn more about her.  I took a chance on her, and though I learned a lot from her -- and will always be grateful for my time with her -- I think it's time to move on. Her name was C++, and she so outshone my previous love, C, that any thoughts of going back evaporated in the heat of this new romance.  She promised me she'd be gentle and not hurt me the way C did.  She promised me she'd clean-up after herself better than C did.  She promised me she'd be less enigmatic and easier to keep happy than C was.  But I was deceived.  Oh sure, as far as truth goes, it wasn't a complete lie.  To some extent she was more fun, more powerful, safer, and easier to maintain.  But it just wasn't good enough -- or at least it's not good enough now. I loved C++, some part of me still does, it's my first-love of programming languages and I recognize its raw power, its blazing speed, and its improvements over its predecessor.  But with today's hardware, at speeds we could only dream to conceive of twenty years ago, that need for speed -- at the cost of all else -- has died, and that has left my feelings for C++ moribund. If I ever need to write an operating system or a device driver, then I might need that speed.  But 99% of the time I don't.  I'm a business-type programmer and chances are 90% of you are too, and even the ones who need speed at all costs may be surprised by how much you sacrifice for that.   That's not to say that I don't want my software to perform, and it's not to say that in the business world we don't care about speed or that our job is somehow less difficult or technical.  There's many times we write programs to handle millions of real-time updates or handle thousands of financial transactions or tracking trading algorithms where every second counts.  But if I choose to write my code in C++ purely for speed chances are I'll never notice the speed increase -- and equally true chances are it will be far more prone to crash and far less easy to maintain.  Nearly without fail, it's the macro-optimizations you need, not the micro-optimizations.  If I choose to write a O(n2) algorithm when I could have used a O(n) algorithm -- that can kill me.  If I choose to go to the database to load a piece of unchanging data every time instead of caching it on first load -- that too can kill me.  And if I cross the network multiple times for pieces of data instead of getting it all at once -- yes that can also kill me.  But choosing an overly powerful and dangerous mid-level language to squeeze out every last drop of performance will realistically not make stock orders process any faster, and more likely than not open up the system to more risk of crashes and resource leaks. And that's when my love for C++ began to die.  When I noticed that I didn't need that speed anymore.  That that speed was really kind of a lie.  Sure, I can be super efficient and pack bits in a byte instead of using separate boolean values.  Sure, I can use an unsigned char instead of an int.  But in the grand scheme of things it doesn't matter as much as you think it does.  The key is maintainability, and that's where C++ failed me.  I like to tell the other developers I work with that there's two levels of correctness in coding: Is it immediately correct? Will it stay correct? That is, you can hack together any piece of code and make it correct to satisfy a task at hand, but if a new developer can't come in tomorrow and make a fairly significant change to it without jeopardizing that correctness, it won't stay correct. Some people laugh at me when I say I now prefer maintainability over speed.  But that is exactly the point.  If you focus solely on speed you tend to produce code that is much harder to maintain over the long hall, and that's a load of technical debt most shops can't afford to carry and end up completely scrapping code before it's time.  When good code is written well for maintainability, though, it can be correct both now and in the future. And you know the best part is?  My new love is nearly as fast as C++, and in some cases even faster -- and better than that, I know C# will treat me right.  Her creators have poured hundreds of thousands of hours of time into making her the sexy beast she is today.  They made her easy to understand and not an enigmatic mess.  They made her consistent and not moody and amorphous.  And they made her perform as fast as I care to go by optimizing her both at compile time and a run-time. Her code is so elegant and easy on the eyes that I'm not worried where she will run to or what she'll pull behind my back.  She is powerful enough to handle all my tasks, fast enough to execute them with blazing speed, maintainable enough so that I can rely on even fairly new peers to modify my work, and rich enough to allow me to satisfy any need.  C# doesn't ask me to clean up her messes!  She cleans up after herself and she tries to make my life easier for me by taking on most of those optimization tasks C++ asked me to take upon myself.  Now, there are many of you who would say that I am the cause of my own grief, that it was my fault C++ didn't behave because I didn't pay enough attention to her.  That I alone caused the pain she inflicted on me.  And to some extent, you have a point.  But she was so high maintenance, requiring me to know every twist and turn of her vast and unrestrained power that any wrong term or bout of forgetfulness was met with painful reminders that she wasn't going to watch my back when I made a mistake.  But C#, she loves me when I'm good, and she loves me when I'm bad, and together we make beautiful code that is both fast and safe. So that's why I'm leaving C++ behind.  She says she's changing for me, but I have no interest in what C++0x may bring.  Oh, I'll still keep in touch, and maybe I'll see her now and again when she brings her problems to my door and asks for some attention -- for I always have a soft spot for her, you see.  But she's out of my house now.  I have three kids and a dog and a cat, and all require me to clean up after them, why should I have to clean up after my programming language as well?

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• Using Event Driven Programming in games, when is it beneficial?

  - by Arthur Wulf White

  I am learning ActionScript 3 and I see the Event flow adheres to the W3C recommendations. From what I learned events can only be captured by the dispatcher unless, the listener capturing the event is a DisplayObject on stage and a parent of the object firing the event. You can capture the events in the capture(before) or bubbling(after) phase depending on Listner and Event setup you use. Does this system lend itself well for game programming? When is this system useful? Could you give an example of a case where using events is a lot better than going without them? Are they somehow better for performance in games? Please do not mention events you must use to get a game running, like Event.ENTER_FRAME Or events that are required to get input from the user like, KeyboardEvent.KEY_DOWN and MouseEvent.CLICK. I am asking if there is any use in firing events that have nothing to do with user input, frame rendering and the likes(that are necessary). I am referring to cases where objects are communicating. Is this used to avoid storing a collection of objects that are on the stage? Thanks Here is some code I wrote as an example of event behavior in ActionScript 3, enjoy. package regression { import flash.display.Shape; import flash.display.Sprite; import flash.events.Event; import flash.events.EventDispatcher; import flash.events.KeyboardEvent; import flash.events.MouseEvent; import flash.events.EventPhase; /** * ... * @author ... */ public class Check_event_listening_1 extends Sprite { public const EVENT_DANCE : String = "dance"; public const EVENT_PLAY : String = "play"; public const EVENT_YELL : String = "yell"; private var baby : Shape = new Shape(); private var mom : Sprite = new Sprite(); private var stranger : EventDispatcher = new EventDispatcher(); public function Check_event_listening_1() { if (stage) init(); else addEventListener(Event.ADDED_TO_STAGE, init); } private function init(e:Event = null):void { trace("test begun"); addChild(mom); mom.addChild(baby); stage.addEventListener(EVENT_YELL, onEvent); this.addEventListener(EVENT_YELL, onEvent); mom.addEventListener(EVENT_YELL, onEvent); baby.addEventListener(EVENT_YELL, onEvent); stranger.addEventListener(EVENT_YELL, onEvent); trace("\nTest1 - Stranger yells with no bubbling"); stranger.dispatchEvent(new Event(EVENT_YELL, false)); trace("\nTest2 - Stranger yells with bubbling"); stranger.dispatchEvent(new Event(EVENT_YELL, true)); stage.addEventListener(EVENT_PLAY, onEvent); this.addEventListener(EVENT_PLAY, onEvent); mom.addEventListener(EVENT_PLAY, onEvent); baby.addEventListener(EVENT_PLAY, onEvent); stranger.addEventListener(EVENT_PLAY, onEvent); trace("\nTest3 - baby plays with no bubbling"); baby.dispatchEvent(new Event(EVENT_PLAY, false)); trace("\nTest4 - baby plays with bubbling"); baby.dispatchEvent(new Event(EVENT_PLAY, true)); trace("\nTest5 - baby plays with bubbling but is not a child of mom"); mom.removeChild(baby); baby.dispatchEvent(new Event(EVENT_PLAY, true)); mom.addChild(baby); stage.addEventListener(EVENT_DANCE, onEvent, true); this.addEventListener(EVENT_DANCE, onEvent, true); mom.addEventListener(EVENT_DANCE, onEvent, true); baby.addEventListener(EVENT_DANCE, onEvent); trace("\nTest6 - Mom dances without bubbling - everyone is listening during capture phase(not target and bubble phase)"); mom.dispatchEvent(new Event(EVENT_DANCE, false)); trace("\nTest7 - Mom dances with bubbling - everyone is listening during capture phase(not target and bubble phase)"); mom.dispatchEvent(new Event(EVENT_DANCE, true)); } private function onEvent(e : Event):void { trace("Event was captured"); trace("\nTYPE : ", e.type, "\nTARGET : ", objToName(e.target), "\nCURRENT TARGET : ", objToName(e.currentTarget), "\nPHASE : ", phaseToString(e.eventPhase)); } private function phaseToString(phase : int):String { switch(phase) { case EventPhase.AT_TARGET : return "TARGET"; case EventPhase.BUBBLING_PHASE : return "BUBBLING"; case EventPhase.CAPTURING_PHASE : return "CAPTURE"; default: return "UNKNOWN"; } } private function objToName(obj : Object):String { if (obj == stage) return "STAGE"; else if (obj == this) return "MAIN"; else if (obj == mom) return "Mom"; else if (obj == baby) return "Baby"; else if (obj == stranger) return "Stranger"; else return "Unknown" } } } /*result : test begun Test1 - Stranger yells with no bubbling Event was captured TYPE : yell TARGET : Stranger CURRENT TARGET : Stranger PHASE : TARGET Test2 - Stranger yells with bubbling Event was captured TYPE : yell TARGET : Stranger CURRENT TARGET : Stranger PHASE : TARGET Test3 - baby plays with no bubbling Event was captured TYPE : play TARGET : Baby CURRENT TARGET : Baby PHASE : TARGET Test4 - baby plays with bubbling Event was captured TYPE : play TARGET : Baby CURRENT TARGET : Baby PHASE : TARGET Event was captured TYPE : play TARGET : Baby CURRENT TARGET : Mom PHASE : BUBBLING Event was captured TYPE : play TARGET : Baby CURRENT TARGET : MAIN PHASE : BUBBLING Event was captured TYPE : play TARGET : Baby CURRENT TARGET : STAGE PHASE : BUBBLING Test5 - baby plays with bubbling but is not a child of mom Event was captured TYPE : play TARGET : Baby CURRENT TARGET : Baby PHASE : TARGET Test6 - Mom dances without bubbling - everyone is listening during capture phase(not target and bubble phase) Event was captured TYPE : dance TARGET : Mom CURRENT TARGET : STAGE PHASE : CAPTURE Event was captured TYPE : dance TARGET : Mom CURRENT TARGET : MAIN PHASE : CAPTURE Test7 - Mom dances with bubbling - everyone is listening during capture phase(not target and bubble phase) Event was captured TYPE : dance TARGET : Mom CURRENT TARGET : STAGE PHASE : CAPTURE Event was captured TYPE : dance TARGET : Mom CURRENT TARGET : MAIN PHASE : CAPTURE */

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• Accelerating 2d object collision with other objects [on hold]

  - by Silent Cave

  Making my very first attempt at game programming with SDL/OpenGL. So I made an object Actor witch can move in all four sides with acceleration. And there are bunch of other rectangles to collide to. the image Movement and collision detection alghorythms work just fine by itself, but when combined to prevent the green rectangle from crossing black rectangles, it gives me a kind of funny resault. Let me show you the code first: from Actor.h class Actor{ public: SDL_Rect * dim; alphaColor * col; float speed; float xlGrav, xrGrav, yuGrav, ydGrav; float acceleration; bool left,right,up,down; Actor(SDL_Rect * dim,alphaColor * col, float speed, float acceleration); bool colides(const SDL_Rect & rect); bool check_for_collisions(const std::vector<SDL_Rect*> & gameObjects ); }; from actor.cpp bool Actor::colides(const SDL_Rect & rect){ if (dim->x + dim->w < rect.x) return false; if (dim->x > rect.x + rect.w) return false; if (dim->y + dim->h < rect.y) return false; if (dim->y > rect.y + rect.h) return false; return true; } movement logic from main.cpp if (actor->left){ if(actor->xlGrav < actor->speed){ actor->xlGrav += actor->speed*actor->acceleration; }else actor->xlGrav = actor->speed; actor->dim->x -= actor->xlGrav; if(actor->check_for_collisions(gameObjects)){ actor->dim->x += actor->xlGrav; actor->xlGrav = 0; } } if (!actor->left){ if(actor->xlGrav - actor->speed*actor->acceleration > 0){ actor->xlGrav -= actor->speed*actor->acceleration; }else actor->xlGrav = 0; actor->dim->x -= actor->xlGrav; if(actor->check_for_collisions(gameObjects)){ actor->dim->x += actor->xlGrav; actor->xlGrav = 0; } } if (actor->right){ if(actor->xrGrav < actor->speed){ actor->xrGrav += actor->speed*actor->acceleration; }else actor->xrGrav = actor->speed; actor->dim->x += actor->xrGrav; if(actor->check_for_collisions(gameObjects)){ actor->dim->x -= actor->xrGrav; actor->xrGrav = 0; } } if (!actor->right){ if(actor->xrGrav - actor->speed*actor->acceleration > 0){ actor->xrGrav -= actor->speed*actor->acceleration; }else actor->xrGrav = 0; actor->dim->x += actor->xrGrav; if(actor->check_for_collisions(gameObjects)){ actor->dim->x -= actor->xrGrav; actor->xrGrav = 0; } } if (actor->up){ if(actor->yuGrav < actor->speed){ actor->yuGrav += actor->speed*actor->acceleration; }else actor->yuGrav = actor->speed; actor->dim->y -= actor->yuGrav; if(actor->check_for_collisions(gameObjects)){ actor->dim->y += actor->yuGrav; actor->yuGrav = 0; } } if (!actor->up){ if(actor->yuGrav - actor->speed*actor->acceleration > 0){ actor->yuGrav -= actor->speed*actor->acceleration; }else actor->yuGrav = 0; actor->dim->y -= actor->yuGrav; if(actor->check_for_collisions(gameObjects)){ actor->dim->y += actor->yuGrav; actor->yuGrav = 0; } } if (actor->down){ if(actor->ydGrav < actor->speed){ actor->ydGrav += actor->speed*actor->acceleration; }else actor->ydGrav = actor->speed; actor->dim->y += actor->ydGrav; if(actor->check_for_collisions(gameObjects)){ actor->dim->y -= actor->ydGrav; actor->ydGrav = 0; } } if (!actor->down){ if(actor->ydGrav - actor->speed*actor->acceleration > 0){ actor->ydGrav -= actor->speed*actor->acceleration; }else actor->ydGrav = 0; actor->dim->y += actor->ydGrav; if(actor->check_for_collisions(gameObjects)){ actor->dim->y -= actor->ydGrav; actor->ydGrav = 0; } } So, if the green box approaches an obstacle from up or left, everything goes as planned - object stops, and it's acceleration drops to zero. But if it comes from bottom or right, it enters into obstacles inner space and starts strangely dance, I'd rather say move in inverted controls. What do I fail to see?

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• Space invaders clone not moving properly

  - by ThePlan

  I'm trying to make a basic space invaders clone in allegro 5, I've got my game set up, basic events and such, here is the code: #include <allegro5/allegro.h> #include <allegro5/allegro_image.h> #include <allegro5/allegro_primitives.h> #include <allegro5/allegro_font.h> #include <allegro5/allegro_ttf.h> #include "Entity.h" // GLOBALS ========================================== const int width = 500; const int height = 500; const int imgsize = 3; bool key[5] = {false, false, false, false, false}; bool running = true; bool draw = true; // FUNCTIONS ======================================== void initSpaceship(Spaceship &ship); void moveSpaceshipRight(Spaceship &ship); void moveSpaceshipLeft(Spaceship &ship); void initInvader(Invader &invader); void moveInvaderRight(Invader &invader); void moveInvaderLeft(Invader &invader); void initBullet(Bullet &bullet); void fireBullet(); void doCollision(); void updateInvaders(); void drawText(); enum key_t { UP, DOWN, LEFT, RIGHT, SPACE }; enum source_t { INVADER, DEFENDER }; int main(void) { if(!al_init()) { return -1; } Spaceship ship; Invader invader; Bullet bullet; al_init_image_addon(); al_install_keyboard(); al_init_font_addon(); al_init_ttf_addon(); ALLEGRO_DISPLAY *display = al_create_display(width, height); ALLEGRO_EVENT_QUEUE *event_queue = al_create_event_queue(); ALLEGRO_TIMER *timer = al_create_timer(1.0 / 60); ALLEGRO_BITMAP *images[imgsize]; ALLEGRO_FONT *font1 = al_load_font("arial.ttf", 20, 0); al_register_event_source(event_queue, al_get_keyboard_event_source()); al_register_event_source(event_queue, al_get_display_event_source(display)); al_register_event_source(event_queue, al_get_timer_event_source(timer)); images[0] = al_load_bitmap("defender.bmp"); images[1] = al_load_bitmap("invader.bmp"); images[2] = al_load_bitmap("explosion.bmp"); al_convert_mask_to_alpha(images[0], al_map_rgb(0, 0, 0)); al_convert_mask_to_alpha(images[1], al_map_rgb(0, 0, 0)); al_convert_mask_to_alpha(images[2], al_map_rgb(0, 0, 0)); initSpaceship(ship); initBullet(bullet); initInvader(invader); al_start_timer(timer); while(running) { ALLEGRO_EVENT ev; al_wait_for_event(event_queue, &ev); if(ev.type == ALLEGRO_EVENT_TIMER) { draw = true; if(key[RIGHT] == true) moveSpaceshipRight(ship); if(key[LEFT] == true) moveSpaceshipLeft(ship); } else if(ev.type == ALLEGRO_EVENT_DISPLAY_CLOSE) running = false; else if(ev.type == ALLEGRO_EVENT_KEY_DOWN) { switch(ev.keyboard.keycode) { case ALLEGRO_KEY_ESCAPE: running = false; break; case ALLEGRO_KEY_LEFT: key[LEFT] = true; break; case ALLEGRO_KEY_RIGHT: key[RIGHT] = true; break; case ALLEGRO_KEY_SPACE: key[SPACE] = true; break; } } else if(ev.type == ALLEGRO_KEY_UP) { switch(ev.keyboard.keycode) { case ALLEGRO_KEY_LEFT: key[LEFT] = false; break; case ALLEGRO_KEY_RIGHT: key[RIGHT] = false; break; case ALLEGRO_KEY_SPACE: key[SPACE] = false; break; } } if(draw && al_is_event_queue_empty(event_queue)) { draw = false; al_draw_bitmap(images[0], ship.pos_x, ship.pos_y, 0); al_flip_display(); al_clear_to_color(al_map_rgb(0, 0, 0)); } } al_destroy_font(font1); al_destroy_event_queue(event_queue); al_destroy_timer(timer); for(int i = 0; i < imgsize; i++) al_destroy_bitmap(images[i]); al_destroy_display(display); } // FUNCTION LOGIC ====================================== void initSpaceship(Spaceship &ship) { ship.lives = 3; ship.speed = 2; ship.pos_x = width / 2; ship.pos_y = height - 20; } void initInvader(Invader &invader) { invader.health = 100; invader.count = 40; invader.speed = 0.5; invader.pos_x = 300; invader.pos_y = 300; } void initBullet(Bullet &bullet) { bullet.speed = 10; } void moveSpaceshipRight(Spaceship &ship) { ship.pos_x += ship.speed; if(ship.pos_x >= width) ship.pos_x = width-30; } void moveSpaceshipLeft(Spaceship &ship) { ship.pos_x -= ship.speed; if(ship.pos_x <= 0) ship.pos_x = 0+30; } However it's not behaving the way I want it to behave, in fact the behavior for the ship movement is un-normal. Basically I specified that the ship only moves when the right/left key is down, however the ship is moving constantly to the direction of the key pressed, it never stops although it should only move while my key is down. Even more weird behavior, when I press the opposite key the ship completely stops no matter what else I press. What's wrong with the code? Why does the ship move constantly even after I specified it only moves when a key is down?

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• C++ strongly typed typedef

  - by Kian

  I've been trying to think of a way of declaring strongly typed typedefs, to catch a certain class of bugs in the compilation stage. It's often the case that I'll typedef an int into several types of ids, or a vector to position or velocity: typedef int EntityID; typedef int ModelID; typedef Vector3 Position; typedef Vector3 Velocity; This can make the intent of code more clear, but after a long night of coding one might make silly mistakes like comparing different kinds of ids, or adding a position to a velocity perhaps. EntityID eID; ModelID mID; if ( eID == mID ) // <- Compiler sees nothing wrong { /*bug*/ } Position p; Velocity v; Position newP = p + v; // bug, meant p + v*s but compiler sees nothing wrong Unfortunately, suggestions I've found for strongly typed typedefs include using boost, which at least for me isn't a possibility (I do have c++11 at least). So after a bit of thinking, I came upon this idea, and wanted to run it by someone. First, you declare the base type as a template. The template parameter isn't used for anything in the definition, however: template < typename T > class IDType { unsigned int m_id; public: IDType( unsigned int const& i_id ): m_id {i_id} {}; friend bool operator==<T>( IDType<T> const& i_lhs, IDType<T> const& i_rhs ); }; Friend functions actually need to be forward declared before the class definition, which requires a forward declaration of the template class. We then define all the members for the base type, just remembering that it's a template class. Finally, when we want to use it, we typedef it as: class EntityT; typedef IDType<EntityT> EntityID; class ModelT; typedef IDType<ModelT> ModelID; The types are now entirely separate. Functions that take an EntityID will throw a compiler error if you try to feed them a ModelID instead, for example. Aside from having to declare the base types as templates, with the issues that entails, it's also fairly compact. I was hoping anyone had comments or critiques about this idea? One issue that came to mind while writing this, in the case of positions and velocities for example, would be that I can't convert between types as freely as before. Where before multiplying a vector by a scalar would give another vector, so I could do: typedef float Time; typedef Vector3 Position; typedef Vector3 Velocity; Time t = 1.0f; Position p = { 0.0f }; Velocity v = { 1.0f, 0.0f, 0.0f }; Position newP = p + v*t; With my strongly typed typedef I'd have to tell the compiler that multypling a Velocity by a Time results in a Position. class TimeT; typedef Float<TimeT> Time; class PositionT; typedef Vector3<PositionT> Position; class VelocityT; typedef Vector3<VelocityT> Velocity; Time t = 1.0f; Position p = { 0.0f }; Velocity v = { 1.0f, 0.0f, 0.0f }; Position newP = p + v*t; // Compiler error To solve this, I think I'd have to specialize every conversion explicitly, which can be kind of a bother. On the other hand, this limitation can help prevent other kinds of errors (say, multiplying a Velocity by a Distance, perhaps, which wouldn't make sense in this domain). So I'm torn, and wondering if people have any opinions on my original issue, or my approach to solving it.

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• Simplex Noise Help

  - by Alex Larsen

  Im Making A Minecraft Like Gae In XNA C# And I Need To Generate Land With Caves This Is The Code For Simplex I Have /// <summary> /// 1D simplex noise /// </summary> /// <param name="x"></param> /// <returns></returns> public static float Generate(float x) { int i0 = FastFloor(x); int i1 = i0 + 1; float x0 = x - i0; float x1 = x0 - 1.0f; float n0, n1; float t0 = 1.0f - x0 * x0; t0 *= t0; n0 = t0 * t0 * grad(perm[i0 & 0xff], x0); float t1 = 1.0f - x1 * x1; t1 *= t1; n1 = t1 * t1 * grad(perm[i1 & 0xff], x1); // The maximum value of this noise is 8*(3/4)^4 = 2.53125 // A factor of 0.395 scales to fit exactly within [-1,1] return 0.395f * (n0 + n1); } /// <summary> /// 2D simplex noise /// </summary> /// <param name="x"></param> /// <param name="y"></param> /// <returns></returns> public static float Generate(float x, float y) { const float F2 = 0.366025403f; // F2 = 0.5*(sqrt(3.0)-1.0) const float G2 = 0.211324865f; // G2 = (3.0-Math.sqrt(3.0))/6.0 float n0, n1, n2; // Noise contributions from the three corners // Skew the input space to determine which simplex cell we're in float s = (x + y) * F2; // Hairy factor for 2D float xs = x + s; float ys = y + s; int i = FastFloor(xs); int j = FastFloor(ys); float t = (float)(i + j) * G2; float X0 = i - t; // Unskew the cell origin back to (x,y) space float Y0 = j - t; float x0 = x - X0; // The x,y distances from the cell origin float y0 = y - Y0; // For the 2D case, the simplex shape is an equilateral triangle. // Determine which simplex we are in. int i1, j1; // Offsets for second (middle) corner of simplex in (i,j) coords if (x0 > y0) { i1 = 1; j1 = 0; } // lower triangle, XY order: (0,0)->(1,0)->(1,1) else { i1 = 0; j1 = 1; } // upper triangle, YX order: (0,0)->(0,1)->(1,1) // A step of (1,0) in (i,j) means a step of (1-c,-c) in (x,y), and // a step of (0,1) in (i,j) means a step of (-c,1-c) in (x,y), where // c = (3-sqrt(3))/6 float x1 = x0 - i1 + G2; // Offsets for middle corner in (x,y) unskewed coords float y1 = y0 - j1 + G2; float x2 = x0 - 1.0f + 2.0f * G2; // Offsets for last corner in (x,y) unskewed coords float y2 = y0 - 1.0f + 2.0f * G2; // Wrap the integer indices at 256, to avoid indexing perm[] out of bounds int ii = i % 256; int jj = j % 256; // Calculate the contribution from the three corners float t0 = 0.5f - x0 * x0 - y0 * y0; if (t0 < 0.0f) n0 = 0.0f; else { t0 *= t0; n0 = t0 * t0 * grad(perm[ii + perm[jj]], x0, y0); } float t1 = 0.5f - x1 * x1 - y1 * y1; if (t1 < 0.0f) n1 = 0.0f; else { t1 *= t1; n1 = t1 * t1 * grad(perm[ii + i1 + perm[jj + j1]], x1, y1); } float t2 = 0.5f - x2 * x2 - y2 * y2; if (t2 < 0.0f) n2 = 0.0f; else { t2 *= t2; n2 = t2 * t2 * grad(perm[ii + 1 + perm[jj + 1]], x2, y2); } // Add contributions from each corner to get the final noise value. // The result is scaled to return values in the interval [-1,1]. return 40.0f * (n0 + n1 + n2); // TODO: The scale factor is preliminary! } public static float Generate(float x, float y, float z) { // Simple skewing factors for the 3D case const float F3 = 0.333333333f; const float G3 = 0.166666667f; float n0, n1, n2, n3; // Noise contributions from the four corners // Skew the input space to determine which simplex cell we're in float s = (x + y + z) * F3; // Very nice and simple skew factor for 3D float xs = x + s; float ys = y + s; float zs = z + s; int i = FastFloor(xs); int j = FastFloor(ys); int k = FastFloor(zs); float t = (float)(i + j + k) * G3; float X0 = i - t; // Unskew the cell origin back to (x,y,z) space float Y0 = j - t; float Z0 = k - t; float x0 = x - X0; // The x,y,z distances from the cell origin float y0 = y - Y0; float z0 = z - Z0; // For the 3D case, the simplex shape is a slightly irregular tetrahedron. // Determine which simplex we are in. int i1, j1, k1; // Offsets for second corner of simplex in (i,j,k) coords int i2, j2, k2; // Offsets for third corner of simplex in (i,j,k) coords /* This code would benefit from a backport from the GLSL version! */ if (x0 >= y0) { if (y0 >= z0) { i1 = 1; j1 = 0; k1 = 0; i2 = 1; j2 = 1; k2 = 0; } // X Y Z order else if (x0 >= z0) { i1 = 1; j1 = 0; k1 = 0; i2 = 1; j2 = 0; k2 = 1; } // X Z Y order else { i1 = 0; j1 = 0; k1 = 1; i2 = 1; j2 = 0; k2 = 1; } // Z X Y order } else { // x0<y0 if (y0 < z0) { i1 = 0; j1 = 0; k1 = 1; i2 = 0; j2 = 1; k2 = 1; } // Z Y X order else if (x0 < z0) { i1 = 0; j1 = 1; k1 = 0; i2 = 0; j2 = 1; k2 = 1; } // Y Z X order else { i1 = 0; j1 = 1; k1 = 0; i2 = 1; j2 = 1; k2 = 0; } // Y X Z order } // A step of (1,0,0) in (i,j,k) means a step of (1-c,-c,-c) in (x,y,z), // a step of (0,1,0) in (i,j,k) means a step of (-c,1-c,-c) in (x,y,z), and // a step of (0,0,1) in (i,j,k) means a step of (-c,-c,1-c) in (x,y,z), where // c = 1/6. float x1 = x0 - i1 + G3; // Offsets for second corner in (x,y,z) coords float y1 = y0 - j1 + G3; float z1 = z0 - k1 + G3; float x2 = x0 - i2 + 2.0f * G3; // Offsets for third corner in (x,y,z) coords float y2 = y0 - j2 + 2.0f * G3; float z2 = z0 - k2 + 2.0f * G3; float x3 = x0 - 1.0f + 3.0f * G3; // Offsets for last corner in (x,y,z) coords float y3 = y0 - 1.0f + 3.0f * G3; float z3 = z0 - 1.0f + 3.0f * G3; // Wrap the integer indices at 256, to avoid indexing perm[] out of bounds int ii = i % 256; int jj = j % 256; int kk = k % 256; // Calculate the contribution from the four corners float t0 = 0.6f - x0 * x0 - y0 * y0 - z0 * z0; if (t0 < 0.0f) n0 = 0.0f; else { t0 *= t0; n0 = t0 * t0 * grad(perm[ii + perm[jj + perm[kk]]], x0, y0, z0); } float t1 = 0.6f - x1 * x1 - y1 * y1 - z1 * z1; if (t1 < 0.0f) n1 = 0.0f; else { t1 *= t1; n1 = t1 * t1 * grad(perm[ii + i1 + perm[jj + j1 + perm[kk + k1]]], x1, y1, z1); } float t2 = 0.6f - x2 * x2 - y2 * y2 - z2 * z2; if (t2 < 0.0f) n2 = 0.0f; else { t2 *= t2; n2 = t2 * t2 * grad(perm[ii + i2 + perm[jj + j2 + perm[kk + k2]]], x2, y2, z2); } float t3 = 0.6f - x3 * x3 - y3 * y3 - z3 * z3; if (t3 < 0.0f) n3 = 0.0f; else { t3 *= t3; n3 = t3 * t3 * grad(perm[ii + 1 + perm[jj + 1 + perm[kk + 1]]], x3, y3, z3); } // Add contributions from each corner to get the final noise value. // The result is scaled to stay just inside [-1,1] return 32.0f * (n0 + n1 + n2 + n3); // TODO: The scale factor is preliminary! } private static byte[] perm = new byte[512] { 151,160,137,91,90,15, 131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,8,99,37,240,21,10,23, 190, 6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,35,11,32,57,177,33, 88,237,149,56,87,174,20,125,136,171,168, 68,175,74,165,71,134,139,48,27,166, 77,146,158,231,83,111,229,122,60,211,133,230,220,105,92,41,55,46,245,40,244, 102,143,54, 65,25,63,161, 1,216,80,73,209,76,132,187,208, 89,18,169,200,196, 135,130,116,188,159,86,164,100,109,198,173,186, 3,64,52,217,226,250,124,123, 5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42, 223,183,170,213,119,248,152, 2,44,154,163, 70,221,153,101,155,167, 43,172,9, 129,22,39,253, 19,98,108,110,79,113,224,232,178,185, 112,104,218,246,97,228, 251,34,242,193,238,210,144,12,191,179,162,241, 81,51,145,235,249,14,239,107, 49,192,214, 31,181,199,106,157,184, 84,204,176,115,121,50,45,127, 4,150,254, 138,236,205,93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180, 151,160,137,91,90,15, 131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,8,99,37,240,21,10,23, 190, 6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,35,11,32,57,177,33, 88,237,149,56,87,174,20,125,136,171,168, 68,175,74,165,71,134,139,48,27,166, 77,146,158,231,83,111,229,122,60,211,133,230,220,105,92,41,55,46,245,40,244, 102,143,54, 65,25,63,161, 1,216,80,73,209,76,132,187,208, 89,18,169,200,196, 135,130,116,188,159,86,164,100,109,198,173,186, 3,64,52,217,226,250,124,123, 5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42, 223,183,170,213,119,248,152, 2,44,154,163, 70,221,153,101,155,167, 43,172,9, 129,22,39,253, 19,98,108,110,79,113,224,232,178,185, 112,104,218,246,97,228, 251,34,242,193,238,210,144,12,191,179,162,241, 81,51,145,235,249,14,239,107, 49,192,214, 31,181,199,106,157,184, 84,204,176,115,121,50,45,127, 4,150,254, 138,236,205,93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180 }; private static int FastFloor(float x) { return (x > 0) ? ((int)x) : (((int)x) - 1); } private static float grad(int hash, float x) { int h = hash & 15; float grad = 1.0f + (h & 7); // Gradient value 1.0, 2.0, ..., 8.0 if ((h & 8) != 0) grad = -grad; // Set a random sign for the gradient return (grad * x); // Multiply the gradient with the distance } private static float grad(int hash, float x, float y) { int h = hash & 7; // Convert low 3 bits of hash code float u = h < 4 ? x : y; // into 8 simple gradient directions, float v = h < 4 ? y : x; // and compute the dot product with (x,y). return ((h & 1) != 0 ? -u : u) + ((h & 2) != 0 ? -2.0f * v : 2.0f * v); } private static float grad(int hash, float x, float y, float z) { int h = hash & 15; // Convert low 4 bits of hash code into 12 simple float u = h < 8 ? x : y; // gradient directions, and compute dot product. float v = h < 4 ? y : h == 12 || h == 14 ? x : z; // Fix repeats at h = 12 to 15 return ((h & 1) != 0 ? -u : u) + ((h & 2) != 0 ? -v : v); } private static float grad(int hash, float x, float y, float z, float t) { int h = hash & 31; // Convert low 5 bits of hash code into 32 simple float u = h < 24 ? x : y; // gradient directions, and compute dot product. float v = h < 16 ? y : z; float w = h < 8 ? z : t; return ((h & 1) != 0 ? -u : u) + ((h & 2) != 0 ? -v : v) + ((h & 4) != 0 ? -w : w); } This Is My World Generation Code Block[,] BlocksInMap = new Block[1024, 256]; public bool IsWorldGenerated = false; Random r = new Random(); private void RunThread() { for (int BH = 0; BH <= 256; BH++) { for (int BW = 0; BW <= 1024; BW++) { Block b = new Block(); if (BH >= 192) { } BlocksInMap[BW, BH] = b; } } IsWorldGenerated = true; } public void GenWorld() { new Thread(new ThreadStart(RunThread)).Start(); } And This Is A Example Of How I Set Blocks Block b = new Block(); b.BlockType = = Block.BlockTypes.Air; This Is A Example Of How I Set Models foreach (Block b in MyWorld) { switch(b.BlockType) { case Block.BlockTypes.Dirt: b.Model = DirtModel; break; ect. } } How Would I Use These To Generate To World (The Block Array) And If Possible Thread It More? btw It's 1024 Wide And 256 Tall

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• Using custom std::set comparator

  - by Omry

  I am trying to change the default order of the items in a set of integers to be lexicographic instead of numeric, and I can't get the following to compile with g++: file.cpp: bool lex_compare(const int64_t &a, const int64_t &b) { stringstream s1,s2; s1 << a; s2 << b; return s1.str() < s2.str(); } void foo() { set<int64_t, lex_compare> > s; s.insert(1); ... } I get the following error: error: type/value mismatch at argument 2 in template parameter list for ‘template<class _Key, class _Compare, class _Alloc> class std::set’ error: expected a type, got ‘lex_compare’ what am I doing wrong?

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• WPF ComboBox Binding to non string object

  - by Mike L

  I'm using MVVM (MVVM Light Toolkit) and have a property on the view model which exposes a list of objects. The objects contain two properties, both strings, which correlate to an abbreviation and a description. I want the ComboBox to expose the pairing as "abbreviation - description". If I use a data template, it does this easily. I have another property on the view model which represents the object that should display as selected -- the chosen item in the ComboBox. I'm binding the ItemsSource to the list, as it represents the universe of available selections, and am trying to bind the SelectedItem to this object. I'm killing myself trying to figure out why I can't get it to work, and feeling more like a fraud by the hour. In trying to learn why this works, I created the same approach with just a list of strings, and a selected string. This works perfectly. So, it clearly has something to do with the typing... perhaps something in choosing equality? Or perhaps it has to do with the data template? Here is the XAML: <Window x:Class="MvvmLight1.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="MainWindow" Height="300" Width="300" DataContext="{Binding Main, Source={StaticResource Locator}}"> <Window.Resources> <ResourceDictionary> <ResourceDictionary.MergedDictionaries> <ResourceDictionary Source="Skins/MainSkin.xaml" /> </ResourceDictionary.MergedDictionaries> <DataTemplate x:Key="DataTemplate1"> <StackPanel Orientation="Horizontal"> <TextBlock TextWrapping="Wrap" Text="{Binding CourtCode}"/> <TextBlock TextWrapping="Wrap" Text=" - "/> <TextBlock TextWrapping="Wrap" Text="{Binding CourtDescription}"/> </StackPanel> </DataTemplate> </ResourceDictionary> </Window.Resources> <Grid x:Name="LayoutRoot"> <ComboBox x:Name="cmbAbbrevDescriptions" Height="35" Margin="25,75,25,25" VerticalAlignment="Top" ItemsSource="{Binding Codes}" ItemTemplate="{DynamicResource DataTemplate1}" SelectedItem="{Binding selectedCode}" /> <ComboBox x:Name="cmbStrings" Height="35" Margin="25" VerticalAlignment="Top" ItemsSource="{Binding strs}" SelectedItem="{Binding selectedStr}"/> </Grid> </Window> And, if helpful, here is the ViewModel: using GalaSoft.MvvmLight; using MvvmLight1.Model; using System.Collections.Generic; namespace MvvmLight1.ViewModel { public class MainViewModel : ViewModelBase { public const string CodesPropertyName = "Codes"; private List<Court> _codes = null; public List<Court> Codes { get { return _codes; } set { if (_codes == value) { return; } var oldValue = _codes; _codes = value; // Update bindings and broadcast change using GalaSoft.Utility.Messenging RaisePropertyChanged(CodesPropertyName, oldValue, value, true); } } public const string selectedCodePropertyName = "selectedCode"; private Court _selectedCode = null; public Court selectedCode { get { return _selectedCode; } set { if (_selectedCode == value) { return; } var oldValue = _selectedCode; _selectedCode = value; // Update bindings and broadcast change using GalaSoft.Utility.Messenging RaisePropertyChanged(selectedCodePropertyName, oldValue, value, true); } } public const string strsPropertyName = "strs"; private List<string> _strs = null; public List<string> strs { get { return _strs; } set { if (_strs == value) { return; } var oldValue = _strs; _strs = value; // Update bindings and broadcast change using GalaSoft.Utility.Messenging RaisePropertyChanged(strsPropertyName, oldValue, value, true); } } public const string selectedStrPropertyName = "selectedStr"; private string _selectedStr = ""; public string selectedStr { get { return _selectedStr; } set { if (_selectedStr == value) { return; } var oldValue = _selectedStr; _selectedStr = value; // Update bindings and broadcast change using GalaSoft.Utility.Messenging RaisePropertyChanged(selectedStrPropertyName, oldValue, value, true); } } /// <summary> /// Initializes a new instance of the MainViewModel class. /// </summary> public MainViewModel() { Codes = new List<Court>(); Court code1 = new Court(); code1.CourtCode = "ABC"; code1.CourtDescription = "A Court"; Court code2 = new Court(); code2.CourtCode = "DEF"; code2.CourtDescription = "Second Court"; Codes.Add(code1); Codes.Add(code2); Court code3 = new Court(); code3.CourtCode = "DEF"; code3.CourtDescription = "Second Court"; selectedCode = code3; selectedStr = "Hello"; strs = new List<string>(); strs.Add("Goodbye"); strs.Add("Hello"); strs.Add("Ciao"); } } } And here is the ridiculously trivial class that is being exposed: using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace MvvmLight1.Model { public class Court { public string CourtCode { get; set; } public string CourtDescription { get; set; } } } Thanks!

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• C# Secure Sockets (SSL)

  - by Matthias Vance

  LS, I was planning on writing a wrapper around the System.Net.Sockets.Socket class, because I didn't feel like using the SSLStream class because I wanted to maintain backwards compatibility with other programs. I found an article which does exactly what I want, but on Windows Mobile. (Link: Enable SSL for managed socket on windows mobile) Quote: My first surprise was that SetSocketOption takes a SocketOptionName enum value as the second parameter, but this enum doesn’t have the equivalent of SO_SECURE. However, C# was nice enough to let me cast an arbitrary integer value to the enum I needed. I tried to do the same, but it doesn't work. Code: private const ushort SO_SECURE = 0x2001; private const ushort SO_SEC_SSL = 0x2004; this.SetSocketOption(SocketOptionLevel.Socket, (SocketOptionName) SO_SECURE, SO_SEC_SSL); Error: An unknown, invalid, or unsupported option or level was specified in a getsockopt or setsockopt call Is there a way to work around this? Kind regards, Matthias Vance

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• how to instantiate template of template

  - by aaa

  hello I have template that looks like this: 100 template<size_t A0, size_t A1, size_t A2, size_t A3> 101 struct mask { 103 template<size_t B0, size_t B1, size_t B2, size_t B3> 104 struct compare { 105 static const bool value = (A0 == B0 && A1 == B1 && A2 == B2 && A3 == B3); 106 }; 107 }; ... 120 const typename boost::enable_if_c< 121 mask<a,b,c,d>::compare<2,3,0,1>::value || ...>::type I am trying to instantiate compare structure. How do I do get value in line 121?

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• What should I do about this random iPhone crash in WebCore?

  - by xtravar

  This happens at random intervals. Any ideas would be appreciated. Obviously it has to do with the UIWebView, but not sure what's going on. Thread 1 Crashed: 0 WebCore 0x0006eb56 WebCore::ScrollView::repaintContentRectangle(WebCore::IntRect const&, bool) + 10 1 WebCore 0x0005ad88 WebCore::FrameView::doDeferredRepaints() + 32 2 WebCore 0x0005ad00 WebCore::FrameView::endDeferredRepaints() + 104 3 WebCore 0x00050818 WebCore::FrameView::layout(bool) + 844 4 WebCore 0x000504c4 WebCore::FrameView::layoutTimerFired(WebCore::Timer<WebCore::FrameView>*) + 4 5 WebCore 0x000504ae WebCore::Timer<WebCore::FrameView>::fired() + 26 6 WebCore 0x000502c6 WebCore::TimerBase::fireTimers(double, WTF::Vector<WebCore::TimerBase*, 0ul> const&) + 102 7 WebCore 0x0004fd1e WebCore::TimerBase::sharedTimerFired() + 66 8 WebCore 0x0004fcb2 WebCore::timerFired(__CFRunLoopTimer*, void*) + 34 9 CoreFoundation 0x00056bac CFRunLoopRunSpecific + 2112 10 CoreFoundation 0x00056356 CFRunLoopRunInMode + 42 11 WebCore 0x0005d6b2 RunWebThread(void*) + 286 12 libSystem.B.dylib 0x0002490a _pthread_body + 10

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• C++ Preprocessor string literal concatenation

  - by ezpz

  I found this regarding how the C preprocessor should handle string literal concatenation (phase 6). However, I can not find anything regarding how this is handled in C++ (does C++ use the C preprocessor?). The reason I ask is that I have the following: const char * Foo::encoding = "\0" "1234567890\0abcdefg"; where encoding is a static member of class Foo. Without the availability of concatenation I wouldnt be able to write that sequence of characters like that. const char * Foo::encoding = "\01234567890\0abcdefg"; Is something entirely different due to the way \012 is interpreted. I dont have access to multiple platforms and I'm curious how confident I should be that the above is always handled correctly - i.e. I will always get { 0, '1', '2', '3', ... }

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• Sort list using stl sort function

  - by Vlad

  I'm trying to sort a list (part of a class) in descending containg items of a struct but it doesn't compile(error: no match for 'operator-' in '__last - __first'): sort(Result.poly.begin(), Result.poly.end(), SortDescending()); And here's SortDescending: struct SortDescending { bool operator()(const term& t1, const term& t2) { return t2.pow < t1.pow; } }; Can anyone tell me what's wrong? Thanks!

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• How to programmatically open the application menu in a .NET CF 2.0 application

  - by PabloG

  I'm developing an C# / .NET CF 2.0 application: it's supposed to be used with the touchscreen deactivated, then, I'm looking for a way to programmatically open the application menu (not the Windows menu). Looking here I tried to adapt the code to the .NET CF 2 but it doesn't work (no error messages neither) public const int WM_SYSCOMMAND = 0x0112; public const int SC_KEYMENU = 0xF100; private void cmdMenu_Click(object sender, EventArgs e) { Message msg = Message.Create(this.Handle, WM_SYSCOMMAND, new IntPtr(SC_KEYMENU), IntPtr.Zero); MessageWindow.SendMessage(ref msg); } Any ideas? TIA, Pablo After Hans answer, I edited the code to Message msg = Message.Create(this.Handle, WM_SYSCOMMAND, new IntPtr(SC_KEYMENU), new IntPtr(115)); // 's' key and added a submenu option as &Search, but it doesn't make any difference

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• IXmlSerializable Dictionary

  - by Shimmy

  I was trying to create a generic Dictionary that implements IXmlSerializable. Here is my trial: Sub Main() Dim z As New SerializableDictionary(Of String, String) z.Add("asdf", "asd") Console.WriteLine(z.Serialize) End Sub Result: <?xml version="1.0" encoding="utf-16"?><Entry key="asdf" value="asd" /> I placed a breakpoint on top of the WriteXml method and I see that when it stops, the writer contains no data at all, and IMHO it should contain the root element and the xml declaration. <Serializable()> _ Public Class SerializableDictionary(Of TKey, TValue) : Inherits Dictionary(Of TKey, TValue) : Implements IXmlSerializable Private Const EntryString As String = "Entry" Private Const KeyString As String = "key" Private Const ValueString As String = "value" Private Shared ReadOnly AttributableTypes As Type() = New Type() {GetType(Boolean), GetType(Byte), GetType(Char), GetType(DateTime), GetType(Decimal), GetType(Double), GetType([Enum]), GetType(Guid), GetType(Int16), GetType(Int32), GetType(Int64), GetType(SByte), GetType(Single), GetType(String), GetType(TimeSpan), GetType(UInt16), GetType(UInt32), GetType(UInt64)} Private Shared ReadOnly GetIsAttributable As Predicate(Of Type) = Function(t) AttributableTypes.Contains(t) Private Shared ReadOnly IsKeyAttributable As Boolean = GetIsAttributable(GetType(TKey)) Private Shared ReadOnly IsValueAttributable As Boolean = GetIsAttributable(GetType(TValue)) Private Shared ReadOnly GetElementName As Func(Of Boolean, String) = Function(isKey) If(isKey, KeyString, ValueString) Public Function GetSchema() As System.Xml.Schema.XmlSchema Implements System.Xml.Serialization.IXmlSerializable.GetSchema Return Nothing End Function Public Sub WriteXml(ByVal writer As XmlWriter) Implements IXmlSerializable.WriteXml For Each entry In Me writer.WriteStartElement(EntryString) WriteData(IsKeyAttributable, writer, True, entry.Key) WriteData(IsValueAttributable, writer, False, entry.Value) writer.WriteEndElement() Next End Sub Private Sub WriteData(Of T)(ByVal attributable As Boolean, ByVal writer As XmlWriter, ByVal isKey As Boolean, ByVal value As T) Dim name = GetElementName(isKey) If attributable Then writer.WriteAttributeString(name, value.ToString) Else Dim serializer As New XmlSerializer(GetType(T)) writer.WriteStartElement(name) serializer.Serialize(writer, value) writer.WriteEndElement() End If End Sub Public Sub ReadXml(ByVal reader As XmlReader) Implements IXmlSerializable.ReadXml Dim empty = reader.IsEmptyElement reader.Read() If empty Then Exit Sub Clear() While reader.NodeType <> XmlNodeType.EndElement While reader.NodeType = XmlNodeType.Whitespace reader.Read() Dim key = ReadData(Of TKey)(IsKeyAttributable, reader, True) Dim value = ReadData(Of TValue)(IsValueAttributable, reader, False) Add(key, value) If Not IsKeyAttributable AndAlso Not IsValueAttributable Then reader.ReadEndElement() Else reader.Read() While reader.NodeType = XmlNodeType.Whitespace reader.Read() End While End While reader.ReadEndElement() End While End Sub Private Function ReadData(Of T)(ByVal attributable As Boolean, ByVal reader As XmlReader, ByVal isKey As Boolean) As T Dim name = GetElementName(isKey) Dim type = GetType(T) If attributable Then Return Convert.ChangeType(reader.GetAttribute(name), type) Else Dim serializer As New XmlSerializer(type) While reader.Name <> name reader.Read() End While reader.ReadStartElement(name) Dim value = serializer.Deserialize(reader) reader.ReadEndElement() Return value End If End Function Public Shared Function Serialize(ByVal dictionary As SerializableDictionary(Of TKey, TValue)) As String Dim sb As New StringBuilder(1024) Dim sw As New StringWriter(sb) Dim xs As New XmlSerializer(GetType(SerializableDictionary(Of TKey, TValue))) xs.Serialize(sw, dictionary) sw.Dispose() Return sb.ToString End Function Public Shared Function Deserialize(ByVal xml As String) As SerializableDictionary(Of TKey, TValue) Dim xs As New XmlSerializer(GetType(SerializableDictionary(Of TKey, TValue))) Dim xr As New XmlTextReader(xml, XmlNodeType.Document, Nothing) Return xs.Deserialize(xr) xr.Close() End Function Public Function Serialize() As String Dim sb As New StringBuilder Dim xw = XmlWriter.Create(sb) WriteXml(xw) xw.Close() Return sb.ToString End Function Public Sub Parse(ByVal xml As String) Dim xr As New XmlTextReader(xml, XmlNodeType.Document, Nothing) ReadXml(xr) xr.Close() End Sub End Class

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• Can't define static abstract string property

  - by goombaloon

  I've run into an interesting problem and am looking for some suggestions on how best to handle this... I have an abstract class that contains a static method that accepts a static string that I would like to define as an abstract property. Problem is that C# doesn't doesn't support the following (see the ConfigurationSectionName and Current properties): public abstract class ProviderConfiguration : ConfigurationSection { private const string _defaultProviderPropertyName = "defaultProvider"; private const string _providersPropertyName = "providers"; protected static string ConfigurationSectionName { get; } public static Configuration Current { get { return Configuration)ConfigurationManager.GetSection(ConfigurationSectionName); } } } I suppose one way to handle this would be to make ConfigurationSectionName NOT abstract and then create a new definition of ConfigurationSectionName in the derived classes, but that feels pretty hackish. Any suggestions would be most welcome. Gratias!!!

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• C++ / error LNK2019 - XpokerEval library

  - by user1068115

  I have been struggling all the afternoon with the XPokerEval Library I downloaded here: http://www.codingthewheel.com/archives/poker-hand-evaluator-roundup#xpokereval I am trying to make the XPokerEval.PokerSim work, using Visual C++ 2010 express but i get the following errors: 1>psim_test.obj : error LNK2019: unresolved external symbol "void __cdecl SimulateHand(char const *,struct SimResults *,float,float,unsigned int)" (?SimulateHand@@YAXPBDPAUSimResults@@MMI@Z) referenced in function _wmain 1>psim_test.obj : error LNK2019: unresolved external symbol "unsigned int __cdecl RankHand(int const *)" (?RankHand@@YAIPBH@Z) referenced in function _wmain Do you think this can be due to a missing link to a library or a incompatibility with my IDE? The script uses the Pokersource Poker-Eval library which is also included in the zip file, I added to the project directories but it still does not work! I cannot figure out why and I am getting mad! Thanks in advance for any tips on this!

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• Memory allocation in case of static variables

  - by eSKay

  I am always confused about static variables, and the way memory allocation happens for them. For example: int a = 1; const int b = 2; static const int c = 3; int foo(int &arg){ arg++; return arg; } How is the memory allocated for a,b and c? What is the difference (in terms of memory) if I call foo(a), foo(b) and foo(c)?

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• Compilation error when using boost serialization library

  - by Shakir

  I have been struggling with this error for a long time. The following is my code snippet. //This is the header file template<typename TElem> class ArrayList { public: /** An accessible typedef for the elements in the array. */ typedef TElem Elem; friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & ptr_; ar & size_; ar & cap_; } Elem *ptr_; // the stored or aliased array index_t size_; // number of active objects index_t cap_; // allocated size of the array; -1 if alias }; template <typename TElem> class gps_position { public: typedef TElem Elem; friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & degrees; ar & minutes; ar & seconds; } private: Elem degrees; index_t minutes; index_t seconds; }; // This is the .cc file #include #include #include #include #include #include #include #include #include "arraylist.h" int main() { // create and open a character archive for output std::ofstream ofs("filename"); // create class instance // gps_position<int> g(35.65, 59, 24.567f); gps_position<float> g; // save data to archive { boost::archive::text_oarchive oa(ofs); // write class instance to archive //oa << g; // archive and stream closed when destructors are called } // ... some time later restore the class instance to its orginal state /* gps_position<int> newg; { // create and open an archive for input std::ifstream ifs("filename"); boost::archive::text_iarchive ia(ifs); // read class state from archive ia >> newg; // archive and stream closed when destructors are called }*/ ArrayList<float> a1; ArrayList<int> a2; a1.Init(22); a2.Init(21); // a1.Resize(30); // a1.Resize(12); // a1.Resize(22); // a2.Resize(22); a1[21] = 99.0; a1[20] = 88.0; for (index_t i = 0; i < a1.size(); i++) { a1[i] = i; a1[i]++; } std::ofstream s("test.txt"); { boost::archive::text_oarchive oa(s); oa << a1; } return 0; } The following is the compilation error i get. In file included from /usr/include/boost/serialization/split_member.hpp:23, from /usr/include/boost/serialization/nvp.hpp:33, from /usr/include/boost/serialization/serialization.hpp:17, from /usr/include/boost/archive/detail/oserializer.hpp:61, from /usr/include/boost/archive/detail/interface_oarchive.hpp:24, from /usr/include/boost/archive/detail/common_oarchive.hpp:20, from /usr/include/boost/archive/basic_text_oarchive.hpp:32, from /usr/include/boost/archive/text_oarchive.hpp:31, from demo.cc:4: /usr/include/boost/serialization/access.hpp: In static member function ‘static void boost::serialization::access::serialize(Archive&, T&, unsigned int) [with Archive = boost::archive::text_oarchive, T = float]’: /usr/include/boost/serialization/serialization.hpp:74: instantiated from ‘void boost::serialization::serialize(Archive&, T&, unsigned int) [with Archive = boost::archive::text_oarchive, T = float]’ /usr/include/boost/serialization/serialization.hpp:133: instantiated from ‘void boost::serialization::serialize_adl(Archive&, T&, unsigned int) [with Archive = boost::archive::text_oarchive, T = float]’ /usr/include/boost/archive/detail/oserializer.hpp:140: instantiated from ‘void boost::archive::detail::oserializer<Archive, T>::save_object_data(boost::archive::detail::basic_oarchive&, const void*) const [with Archive = boost::archive::text_oarchive, T = float]’ demo.cc:105: instantiated from here /usr/include/boost/serialization/access.hpp:109: error: request for member ‘serialize’ in ‘t’, which is of non-class type ‘float’ Please help me out.

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• GSL-GNU in Visual studio

  - by Arman

  I have visual studio 2008, I want to integrate GSL library in my project, kindly give me some guidelines so that I can make it possible. I have added the GSL library but the following error come. Error 1 error LNK2028: unresolved token (0A000010) "extern "C" void __cdecl gsl_matrix_set(struct gsl_matrix *,unsigned int,unsigned int,double)" (?gsl_matrix_set@@$$J0YAXPAUgsl_matrix@@IIN@Z) referenced in function "int __cdecl main(void)" (?main@@$$HYAHXZ) Error 2 error LNK2028: unresolved token (0A000011) "extern "C" struct gsl_matrix * __cdecl gsl_matrix_alloc(unsigned int,unsigned int)" (?gsl_matrix_alloc@@$$J0YAPAUgsl_matrix@@II@Z) referenced in function "int __cdecl main(void)" (?main@@$$HYAHXZ) Error 3 error LNK2028: unresolved token (0A000014) "extern "C" double __cdecl gsl_matrix_get(struct gsl_matrix const *,unsigned int,unsigned int)" (?gsl_matrix_get@@$$J0YANPBUgsl_matrix@@II@Z) referenced in function "int __cdecl main(void)" (?main@@$$HYAHXZ) Error 4 error LNK2019: unresolved external symbol "extern "C" double __cdecl gsl_matrix_get(struct gsl_matrix const *,unsigned int,unsigned int)" (?gsl_matrix_get@@$$J0YANPBUgsl_matrix@@II@Z) referenced in function "int __cdecl main(void)" (?main@@$$HYAHXZ) Error 5 error LNK2019: unresolved external symbol "extern "C" void __cdecl gsl_matrix_set(struct gsl_matrix *,unsigned int,unsigned int,double)" (?gsl_matrix_set@@$$J0YAXPAUgsl_matrix@@IIN@Z) referenced in function "int __cdecl main(void)" (?main@@$$HYAHXZ)

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• Difference between Singleton implemention using pointer and using static object

  - by Anon

  EDIT: Sorry my question was not clear, why do books/articles prefer implementation#1 over implementation#2? What is the actual advantage of using pointer in implementation of Singleton class vs using a static object? Why do most books prefer this class Singleton { private: static Singleton *p_inst; Singleton(); public: static Singleton * instance() { if (!p_inst) { p_inst = new Singleton(); } return p_inst; } }; over this class Singleton { public: static Singleton& Instance() { static Singleton inst; return inst; } protected: Singleton(); // Prevent construction Singleton(const Singleton&); // Prevent construction by copying Singleton& operator=(const Singleton&); // Prevent assignment ~Singleton(); // Prevent unwanted destruction };

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• Another design-related C++ question

  - by Kotti

  Hi! I am trying to find some optimal solutions in C++ coding patterns, and this is one of my game engine - related questions. Take a look at the game object declaration (I removed almost everything, that has no connection with the question). // Abstract representation of a game object class Object : public Entity, IRenderable, ISerializable { // Object parameters // Other not really important stuff public: // @note Rendering template will never change while // the object 'lives' Object(RenderTemplate& render_template, /* params */) : /*...*/ { } private: // Object rendering template RenderTemplate render_template; public: /** * Default object render method * Draws rendering template data at (X, Y) with (Width, Height) dimensions * * @note If no appropriate rendering method overload is specified * for any derived class, this method is called * * @param Backend & b * @return void * @see */ virtual void Render(Backend& backend) const { // Render sprite from object's // rendering template structure backend.RenderFromTemplate( render_template, x, y, width, height ); } }; Here is also the IRenderable interface declaration: // Objects that can be rendered interface IRenderable { /** * Abstract method to render current object * * @param Backend & b * @return void * @see */ virtual void Render(Backend& b) const = 0; } and a sample of a real object that is derived from Object (with severe simplifications :) // Ball object class Ball : public Object { // Ball params public: virtual void Render(Backend& b) const { b.RenderEllipse(/*params*/); } }; What I wanted to get is the ability to have some sort of standard function, that would draw sprite for an object (this is Object::Render) if there is no appropriate overload. So, one can have objects without Render(...) method, and if you try to render them, this default sprite-rendering stuff is invoked. And, one can have specialized objects, that define their own way of being rendered. I think, this way of doing things is quite good, but what I can't figure out - is there any way to split the objects' "normal" methods (like Resize(...) or Rotate(...)) implementation from their rendering implementation? Because if everything is done the way described earlier, a common .cpp file, that implements any type of object would generally mix the Resize(...), etc methods implementation and this virtual Render(...) method and this seems to be a mess. I actually want to have rendering procedures for the objects in one place and their "logic implementation" - in another. Is there a way this can be done (maybe alternative pattern or trick or hint) or this is where all this polymorphic and virtual stuff sucks in terms of code placement?

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• IXmlSerializable Dictionary problem

  - by Shimmy

  I was trying to create a generic Dictionary that implements IXmlSerializable. Here is my trial: Sub Main() Dim z As New SerializableDictionary(Of String, String) z.Add("asdf", "asd") Console.WriteLine(z.Serialize) End Sub Result: <?xml version="1.0" encoding="utf-16"?><Entry key="asdf" value="asd" /> I placed a breakpoint on top of the WriteXml method and I see that when it stops, the writer contains no data at all, and IMHO it should contain the root element and the xml declaration. <Serializable()> _ Public Class SerializableDictionary(Of TKey, TValue) : Inherits Dictionary(Of TKey, TValue) : Implements IXmlSerializable Private Const EntryString As String = "Entry" Private Const KeyString As String = "key" Private Const ValueString As String = "value" Private Shared ReadOnly AttributableTypes As Type() = New Type() {GetType(Boolean), GetType(Byte), GetType(Char), GetType(DateTime), GetType(Decimal), GetType(Double), GetType([Enum]), GetType(Guid), GetType(Int16), GetType(Int32), GetType(Int64), GetType(SByte), GetType(Single), GetType(String), GetType(TimeSpan), GetType(UInt16), GetType(UInt32), GetType(UInt64)} Private Shared ReadOnly GetIsAttributable As Predicate(Of Type) = Function(t) AttributableTypes.Contains(t) Private Shared ReadOnly IsKeyAttributable As Boolean = GetIsAttributable(GetType(TKey)) Private Shared ReadOnly IsValueAttributable As Boolean = GetIsAttributable(GetType(TValue)) Private Shared ReadOnly GetElementName As Func(Of Boolean, String) = Function(isKey) If(isKey, KeyString, ValueString) Public Function GetSchema() As System.Xml.Schema.XmlSchema Implements System.Xml.Serialization.IXmlSerializable.GetSchema Return Nothing End Function Public Sub WriteXml(ByVal writer As XmlWriter) Implements IXmlSerializable.WriteXml For Each entry In Me writer.WriteStartElement(EntryString) WriteData(IsKeyAttributable, writer, True, entry.Key) WriteData(IsValueAttributable, writer, False, entry.Value) writer.WriteEndElement() Next End Sub Private Sub WriteData(Of T)(ByVal attributable As Boolean, ByVal writer As XmlWriter, ByVal isKey As Boolean, ByVal value As T) Dim name = GetElementName(isKey) If attributable Then writer.WriteAttributeString(name, value.ToString) Else Dim serializer As New XmlSerializer(GetType(T)) writer.WriteStartElement(name) serializer.Serialize(writer, value) writer.WriteEndElement() End If End Sub Public Sub ReadXml(ByVal reader As XmlReader) Implements IXmlSerializable.ReadXml Dim empty = reader.IsEmptyElement reader.Read() If empty Then Exit Sub Clear() While reader.NodeType <> XmlNodeType.EndElement While reader.NodeType = XmlNodeType.Whitespace reader.Read() Dim key = ReadData(Of TKey)(IsKeyAttributable, reader, True) Dim value = ReadData(Of TValue)(IsValueAttributable, reader, False) Add(key, value) If Not IsKeyAttributable AndAlso Not IsValueAttributable Then reader.ReadEndElement() Else reader.Read() While reader.NodeType = XmlNodeType.Whitespace reader.Read() End While End While reader.ReadEndElement() End While End Sub Private Function ReadData(Of T)(ByVal attributable As Boolean, ByVal reader As XmlReader, ByVal isKey As Boolean) As T Dim name = GetElementName(isKey) Dim type = GetType(T) If attributable Then Return Convert.ChangeType(reader.GetAttribute(name), type) Else Dim serializer As New XmlSerializer(type) While reader.Name <> name reader.Read() End While reader.ReadStartElement(name) Dim value = serializer.Deserialize(reader) reader.ReadEndElement() Return value End If End Function Public Shared Function Serialize(ByVal dictionary As SerializableDictionary(Of TKey, TValue)) As String Dim sb As New StringBuilder(1024) Dim sw As New StringWriter(sb) Dim xs As New XmlSerializer(GetType(SerializableDictionary(Of TKey, TValue))) xs.Serialize(sw, dictionary) sw.Dispose() Return sb.ToString End Function Public Shared Function Deserialize(ByVal xml As String) As SerializableDictionary(Of TKey, TValue) Dim xs As New XmlSerializer(GetType(SerializableDictionary(Of TKey, TValue))) Dim xr As New XmlTextReader(xml, XmlNodeType.Document, Nothing) Return xs.Deserialize(xr) xr.Close() End Function Public Function Serialize() As String Dim sb As New StringBuilder Dim xw = XmlWriter.Create(sb) WriteXml(xw) xw.Close() Return sb.ToString End Function Public Sub Parse(ByVal xml As String) Dim xr As New XmlTextReader(xml, XmlNodeType.Document, Nothing) ReadXml(xr) xr.Close() End Sub End Class

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• Still getting duplicate token error after calling DuplicateTokenEx for impersonated token

  - by atconway

  I'm trying to return a Sytem.IntPtr from a service call so that the client can use impersonation to call some code. My imersonation code works properly if not passing the token back from a WCF service. I'm not sure why this is not working. I get the following error: "Invalid token for impersonation - it cannot be duplicated." Here is my code that does work except when I try to pass the token back from a service to a WinForm C# client to then impersonate. [DllImport("advapi32.dll", EntryPoint = "DuplicateTokenEx")] public extern static bool DuplicateTokenEx(IntPtr ExistingTokenHandle, uint dwDesiredAccess, ref SECURITY_ATTRIBUTES lpThreadAttributes, int TokenType, int ImpersonationLevel, ref IntPtr DuplicateTokenHandle); private IntPtr tokenHandle = new IntPtr(0); private IntPtr dupeTokenHandle = new IntPtr(0); [StructLayout(LayoutKind.Sequential)] public struct SECURITY_ATTRIBUTES { public int Length; public IntPtr lpSecurityDescriptor; public bool bInheritHandle; } public enum SecurityImpersonationLevel { SecurityAnonymous = 0, SecurityIdentification = 1, SecurityImpersonation = 2, SecurityDelegation = 3 } public enum TokenType { TokenPrimary = 1, TokenImpersonation = 2 } private const int MAXIMUM_ALLOWED = 0x2000000; [PermissionSetAttribute(SecurityAction.Demand, Name = "FullTrust")] public System.IntPtr GetWindowsUserToken(string UserName, string Password, string DomainName) { IntPtr tokenHandle = new IntPtr(0); IntPtr dupTokenHandle = new IntPtr(0); const int LOGON32_PROVIDER_DEFAULT = 0; //This parameter causes LogonUser to create a primary token. const int LOGON32_LOGON_INTERACTIVE = 2; //Initialize the token handle tokenHandle = IntPtr.Zero; //Call LogonUser to obtain a handle to an access token for credentials supplied. bool returnValue = LogonUser(UserName, DomainName, Password, LOGON32_LOGON_INTERACTIVE, LOGON32_PROVIDER_DEFAULT, ref tokenHandle); //Make sure a token was returned; if no populate the ResultCode and throw an exception: int ResultCode = 0; if (false == returnValue) { ResultCode = Marshal.GetLastWin32Error(); throw new System.ComponentModel.Win32Exception(ResultCode, "API call to LogonUser failed with error code : " + ResultCode); } SECURITY_ATTRIBUTES sa = new SECURITY_ATTRIBUTES(); sa.bInheritHandle = true; sa.Length = Marshal.SizeOf(sa); sa.lpSecurityDescriptor = (IntPtr)0; bool dupReturnValue = DuplicateTokenEx(tokenHandle, MAXIMUM_ALLOWED, ref sa, (int)SecurityImpersonationLevel.SecurityDelegation, (int)TokenType.TokenImpersonation, ref dupTokenHandle); int ResultCodeDup = 0; if (false == dupReturnValue) { ResultCodeDup = Marshal.GetLastWin32Error(); throw new System.ComponentModel.Win32Exception(ResultCode, "API call to DuplicateToken failed with error code : " + ResultCode); } //Return the user token return dupTokenHandle; } Any idea if I'm not using the call to DuplicateTokenEx correctly? According to the MSDN documentation I read here I should be able to create a token valid for delegation and use across the context on remote systems. When 'SecurityDelegation' is used, the server process can impersonate the client's security context on remote systems. Thanks!

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• Memory leak returning QIcon

  - by Stefano

  I started using Qt but I'm facing a big problem: I implemented my custom model that inhrerits from the QAbstractListModel class. What I want to do is to display a list with icon. All works and the image is shown with my code but it creates a memory leak. If I don't return the icon no memory leak is detected. class MyModel : public QAbstractListModel { public: ... private: QIcon myicon; } QVariant MyModel::data(const QModelIndex &index, int role) const { ... if (role == Qt::DecorationRole) { return this->myicon; } ... }

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