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• best practice for initializing class members in php

  - by rgvcorley

  I have lots of code like this in my constructors:- function __construct($params) { $this->property = isset($params['property']) ? $params['property'] : default_val; } Is it better to do this rather than specify the default value in the property definition? i.e. public $property = default_val? Sometimes there is logic for the default value, and some default values are taken from other properties, which was why I was doing this in the constructor. Should I be using setters so all the logic for default values is separated?

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• Attributes and Behaviours in game object design

  - by Brukwa

  Recently I have read interesting slides about game object design written by Marcin Chady Theory and Practice of the Game Object Component Architecture. I have prototyped quick sample that utilize all Attributes\Behaviour idea with some sample data. Now I have faced a little problem when I added a RenderingSystem to my prototype application. I have created an object with RenderBehaviour which listens for messages (OnMessage function) like MovedObject in order to mark them as invalid and in OnUpdate pass I am inserting a new renderable object to rederer queue. I have noticed that rendering updates should be the last thing made in single frame and this causes RenderBehaviour to depend on any other Behaviour that changes object position (i.ex. PhysicsSystem and PhysicsBehaviour). I am not even sure if I am doing this the way it should be. Do you have any clues that might put me on the right track?

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• Data structures for storing finger/stylus movements in drawing application?

  - by mattja?øb

  I have a general question about creating a drawing application, the language could be C++ or ObjectiveC with OpenGL. I would like to hear what are the best methods and practices for storing strokes data. Think of the many iPad apps that allow you to draw with your finger (or a stylus) or any other similar function on a desktop app. To summarize, the data structure must: be highly responsive to the movement store precise values (close in space / time) usable for rendering the strokes with complex textures (textures based on the dynamic of the stroke etc) exportable to a text file for saving/loading

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• If you need more than 3 levels of indentation, you're screwed?

  - by jokoon

  Per the Linux kernel coding style document: The answer to that is that if you need more than 3 levels of indentation, you're screwed anyway, and should fix your program. What can I deduct from this quote? On top of the fact that too long methods are hard to maintain, are they hard or impossible to optimize for the compiler? I don't really understand if this quote encourages better coding practice or is really a mathematical / algorithmic sort of truth. I also read in some C++ optimizing guide that dividing up a program into more function improves its design is a common thing taught at school, but it should be not done too much, since it can turn into a lot of JMP calls (even if the compiler can inline some methods by itself).

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• Finding the median of the merged array of two sorted arrays in O(logN)?

  - by user176517

  Refering to the solution present at MIT handout I have tried to figure out the solution myself but have got stuck and I believe I need help to understand the following points. In the function header used in the solution MEDIAN -SEARCH (A[1 . . l], B[1 . . m], max(1,n/2 - m), min(l, n/2)) I do not understand the last two arguments why not simply 1, l why the max and min respectively. Thanking You.

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• How often do CPUs make calculation errors?

  - by veryfoolish

  In Dijkstra's Notes on Structured Programming he talks a lot about the provability of computer programs as abstract entities. As a corollary, he remarks how testing isn't enough. E.g., he points out the fact that it would be impossible to test a multiplication function f(x,y) = x*y for any large values of x and y across the entire ranges of x and y. My question concerns his misc. remarks on "lousy hardware". I know the essay was written in the 1970s when computer hardware was less reliable, but computers still aren't perfect, so they must make calculation mistakes sometimes. Does anybody know how often this happens or if there are any statistics on this?

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• PCI hotplug doesn't seem to work

  - by user245454

  In virsh I detach a PCI bus from host and attach it to a VM. I don't see any errors in these steps. But I don't see the PCI device listed in the VM. virsh # nodedev-dettach pci_0000_01_00_0 Device pci_0000_01_00_0 dettached virsh # attach-device VM1 pci_add.xml Device attached successfully $ cat pci_add.xml <hostdev mode='subsystem' type='pci' managed='yes'> <source> <address domain='0x000' bus='0x01' slot='0x00' function='0x0'/> </source> </hostdev> Is PCI hot plug not supported? I am using Ubuntu 12.04.3(kernel 3.8.0-34). I can add the same PCI device through virsh edit VM1 and start the VM1. This way I am able to see the device.

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• What is the correct way to use glTexCoordPointer?

  - by RubyKing

  I'm trying to work out how to use this function glTexCoordPointer. The man page states that I must set a pointer to the first element of the array that uses the texture cordinate. Here is my array: static const GLfloat GUIVertices[] = { //FIRST QUAD 1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, -1.0f, 1.0f, 0.0f, 1.0f, 0.0f, 0.0f, -1.0f, 0.94f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.94f, 0.0f, 1.0f, 1.0f, 1.0f, //2ND QUAD // x y z w X Y 1.0f, -1.0f, 0.0f, 1.0f, 1.0f, 0.0f, -1.0f, -1.0f, 0.0f, 1.0f, 0.0f, 0.0f, -1.0f, -0.94f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f, -0.94f, 0.0f, 1.0f, 1.0f, 1.0, }; But how do I set the pointer correctly for the fifth element on the 2nd quad first row? I was thinking something like this: glTexCoordPointer(1, GL_FLOAT, 6, reinterpret_cast<const GLvoid *>(29 * sizeof(float)));

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• Strange problem with libc: undefined reference to `crypt'

  - by sorush-r

  I moved from Archlinux to Kubuntu 12.04 yesterday. I compiled buildroot 2012.08 on Archlinux without any problem. Though on Kubuntu libcrypt seems to be broken. sysvinit can't find it anywhere. glibc-dev and all dependencies are installed. How do I link to libcrypt? Or, which package containts that library? ... bc-gcc sulogin.o -o sulogin sulogin.o: In function `main': sulogin.c:(.text+0x49d): undefined reference to `crypt' collect2: ld returned 1 exit status

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• When tracking which elements were clicked e.target.id is sometimes empty [migrated]

  - by Ivan

  I am trying to test the following JavaScript code, which is meant to keep track of the timing of user responses on a multiple choice survey: document.onclick = function(e) { var event = e || window.event; var target = e.target || e.srcElement; //time tracking var ClickTrackDate = new Date; var ClickData = ""; ClickData = target.id + "=" + ClickTrackDate.getUTCHours() + ":" + ClickTrackDate.getUTCMinutes() + ":" + ClickTrackDate.getUTCSeconds() +";"; document.getElementById("txtTest").value += ClickData; alert(target.id); // for testing } Usually target.id equals to the the id of the clicked element, as you would expect, but sometimes target.id is empty, seemingly at random, any ideas?

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• Enabling and Disabling Colliders Unity

  - by Blue

  I'm trying to make the collider appear every 1 second. But I can't get the code write. I tried enabling the collider under a boolean and putting a yield to make it every second or so. But it's not working(gives me an error: Update() can not be a coroutine.). How would I fix this? Would I need a timer system and set the collider to be enabled every 'x' seconds and disabled every 'y' seconds? var waitTime : float = 1; var trigger : boolean = false; function Update () { if(!trigger){ collider.enabled = false; yield WaitForSeconds(waitTime); } if(trigger){ collider.enabled = true; yield WaitForSeconds(waitTime); } } }

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• Problems using PHP on a Plesk Windows dedicated server

  - by wpsmdouble

  I'm having a few issues with my dedicated Windows server that has a Plesk panel: 1.) I can't send e-mail via PHP's mail() function, it always returns the following error: SMTP server response: 550 Requested action not taken: mailbox unavailable or not local Which setting should I alter in order to enable sending mail? 2.) The exec() and passthru() PHP functions don't work; their outputs are blank even when I try to run simple commands such as dir. Is there an option that I can toggle in the control panel to enable this functionality?

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• How to use GetActiveUniform (in SharpGL)?

  - by frankie

  Generally, guesting is in header. I cannot understand how to use GetActiveUniform function. public void GetActiveUniform(uint program, uint index, int bufSize, int[] length, int[] size, uint[] type, string name); My attempt looks like this (everything is compiled and linked): var uniformSize = new int[1]; var unifromLength = new int[1]; var uniformType = new uint[1]; var uniformName = ""; Gl.GetActiveUniform(Id, index, uniformNameMaxLength[0], unifromLength, uniformSize, uniformType, uniformName); After call I get proper uniformSize, length and type, but not name.

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• 2D Topdown Shooter Mouse Movement

  - by Jarmo

  I'm trying to make a topdown 2D space game for my school project. I'm almost done but I just want to add a few little things to make the game more fun to play. if (keystate.IsKeyDown(Keys.W)) { vPlayerPos += Vector2.Normalize(new Vector2(Mouse.GetState().X - vPlayerPos.X, Mouse.GetState().Y - vPlayerPos.Y)) * 3; rPlayer.X = (int)vPlayerPos.X; rPlayer.Y = (int)vPlayerPos.Y; } if (keystate.IsKeyDown(Keys.S)) { vPlayerPos += Vector2.Normalize(new Vector2(Mouse.GetState().X - vPlayerPos.X, Mouse.GetState().Y - vPlayerPos.Y)) * -3; rPlayer.X = (int)vPlayerPos.X; rPlayer.Y = (int)vPlayerPos.Y; } This is what i use to move towards and away from my mouse crossair. I tried to make a somewhat similar function to make it strafe with "A" and "D". But for some reason I just couldn't get it done. Any thoughts?

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• Repelling a rigidbody in the direction an object is rotating

  - by ndg

  Working in Unity, I have a game object which I rotate each frame, like so: void Update() { transform.Rotate(new Vector3(0, 1, 0) * speed * Time.deltaTime); } However, I'm running into problems when it comes to applying a force to rigidbodies that collide with this game objects sphere collider. The effect I'm hoping to achieve is that objects which touch the collider are thrown in roughly the same direction as the object is rotating. To do this, I've tried the following: Vector3 force = ((transform.localRotation * Vector3.forward) * 2000) * Time.deltaTime; collision.gameObject.rigidbody.AddForce(force, ForceMode.Impulse); Unfortunately this doesn't always match the rotation of the object. To debug the issue, I wrote a simple OnDrawGizmos script, which (strangely) appears to draw the line correctly oriented to the rotation. void OnDrawGizmos() { Vector3 pos = transform.position + ((transform.localRotation * Vector3.forward) * 2); Debug.DrawLine(transform.position, pos, Color.red); } You can see the result of the OnDrawGizmos function below: What am I doing wrong?

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• Game getting progressively laggier?

  - by Valentin Krummenacher

  I have a small game in HTML5 that uses socket.io to communicate with a node.js server. Now my problem is that, eversince I did my last update on it it seems to have something "chunk up" in the background making it laggier and laggier the longer it runs. In the update were a few temporary local variables being defined with var(you know, variables that are only used during one function and then not needed anymore) alongside with alot of other changes, and I am not even sure if this update or something else is causing this. Might the "var" have caused it? Or what other reasons might this strange complication have?

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• To View multiple uploaded images [closed]

  - by Nilesh Sonawane

  PHP Javascript Image Upload function updatepicture(pic) { document.getElementById("image").setAttribute("src", pic); document.getElementById("image1").setAttribute("src", pic); document.getElementById("image2").setAttribute("src", pic); } Vastu deals Image Upload Upload message will go here. //query for insert timepass.php 0) { if ($_FILES['file']['size'] parent.document.getElementById("message").innerHTML = ""; parent.document.getElementById("file").value = ""; window.parent.updatepicture(""); parent.document.getElementById("message").innerHTML = "There was an error uploading your image. Please try again later."; parent.document.getElementById("message").innerHTML = "Your file is larger than 150kb. Please choose a different picture.";

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• How to get files that have been added/modifed in a batch file

  - by Chris L

  I have the following batch file which concatenates all of the files in a folder that have a .sql ending. set func=%~dp0%Stored Procedures\*.sql for %%i in (%func%) do type "%%i" >>InstallScript.sql We use SVN as our repository, and we're using branching. Currently the script concatenates all the .sql files, even the ones that haven't changed. I'd like to change it so it only concatenates files that have been modified and/or created after the branch was created. We can do that by looking at the datetime on the .svn folder in each folder(there's a Stored Procedure, View, Function subfolders). But I don't know how to do that with batch files. Ideally something like this(psuedo code): set func=%~dp0%Stored Procedures\*.sql set branchDateTime=GetDateTime(%~dp0%.svn) <- Gets the datetime when the .svn folder was created for %%i in (%func%) { if(%%i.LastModifiedOrCreated > branchDateTime) do type "%%i" >> InstallScript.sql }

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• How to program a cutting tool for 3D model in game

  - by Jesse S

  I'm looking for a resource to figure out how to program a function to cut a 3d model in game. Example: Enemy/NPC is sliced into 2 pieces with a sword. His body is not hollow, you can see bloody texture where normally a 'polygon hole' would be. The first step is to actually 'cut/slice' the model, then add in polygons to fill the hole in the model. I know this can be done in 3D modelling software, but I'm not sure how to go about doing this in a game, code-wise. I do not wish to use 'pre cut-up" models, the code will determine where the cut is. Any pointers in the right direction would be greatly appreciated.

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• HW resources for the device driver [closed]

  - by VladimirLenin

  Need to provide memory and IRQ resources to the Linux kernel in order to bring up the CAN controller. Have no idea how to get them. Below is the structure I need to fill in. This structure I have taken for example, this is for the Run-Time Clock, but I need for CAN controller. Both are on the same board, and there are constants for RT Clock (and all other devices), but not for my CAN chip. When looking at the subject chip driver's code (sp_probe() function), I see it needs the same type resources. struct resource tegra_rtc_resources[] = { [0] = { .start = ???, .end = ???, .flags = IORESOURCE_MEM, }, [1] = { .start = ???, .end = ???, .flags = IORESOURCE_IRQ, }, };

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• which is better performance, using a disposable local variable or reusing a global one?

  - by petervaz

  This is for an android game. Suppose I have a function that is called several times for second and do some calculations involving an arraylist (or any other complex objects for what matter). Which approach would be preffered? local: private void doStuff(){ ArrayList<Type> XList = new ArrayList<Type>(); // do stuff with list } global: private ArrayList<Type> XList = new ArrayList<Type>(); private void doStuff(){ XList.clear(); // do stuff with list }

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• Determining the angle to fire a shot when target and shooter moves, and bullet moves with shooter velocity added in

  - by Azaral

  I saw this question: Predicting enemy position in order to have an object lead its target and followed the link in the answer to stack overflow. In the stack overflow page I used the 2nd answer, the one that is a large mathematical derivation. My situation is a little different though. My first question though is will the answer provided in the stack overflow page even work to begin with, assuming the original circumstances of moving target and stationary shooter. My situation is a little different than that situation. My target moves, the shooter moves, and the bullets from the shooter start off with the velocities in x and y added to the bullets' x and y velocities. If you are sliding to the right, the bullets will remain in front of you as you move so as long as your velocity remains constant. What I'm trying to do is to get the enemy to be able to determine where they need to shoot in order to hit the player. Unless the player and enemy is stationary, the velocity from the ship adding to the velocity of the bullets will cause a miss. I'd rather like to prevent that. I used the formula in the stack overflow answer and did what I thought were the appropriate adjustments. I've been banging at this for the last four hours and I just can't make it click. It is probably something really simple and boneheaded that I am missing (that seems to be a lot of my problems lately). Here is the solution presented from the stack overflow answer: It boils down to solving a quadratic equation of the form: a * sqr(x) + b * x + c == 0 Note that by sqr I mean square, as opposed to square root. Use the following values: a := sqr(target.velocityX) + sqr(target.velocityY) - sqr(projectile_speed) b := 2 * (target.velocityX * (target.startX - cannon.X) + target.velocityY * (target.startY - cannon.Y)) c := sqr(target.startX - cannon.X) + sqr(target.startY - cannon.Y) Now we can look at the discriminant to determine if we have a possible solution. disc := sqr(b) - 4 * a * c If the discriminant is less than 0, forget about hitting your target -- your projectile can never get there in time. Otherwise, look at two candidate solutions: t1 := (-b + sqrt(disc)) / (2 * a) t2 := (-b - sqrt(disc)) / (2 * a) Note that if disc == 0 then t1 and t2 are equal. If there are no other considerations such as intervening obstacles, simply choose the smaller positive value. (Negative t values would require firing backward in time to use!) Substitute the chosen t value back into the target's position equations to get the coordinates of the leading point you should be aiming at: aim.X := t * target.velocityX + target.startX aim.Y := t * target.velocityY + target.startY Here is my code, after being corrected by Sam Hocevar (thank you again for your help!). It still doesn't work. For some reason it never enters the section of code inside the if(disc = 0) (obviously because it is always less than zero but...). However, if I plug the numbers from my game log on the enemy and player positions and velocities it outputs a valid firing solution. I have looked at the code side by side a couple of times now and I can't find any differences. There has got to be something simple I'm missing here. If someone else could look at this code and determine what is going on here I'd appreciate it. I know it's not going through that section because if it were, shouldShoot would become true and the enemy would be blasting away at the player. This section calls the function in question, CalculateShootHeading() if(shouldMove) { UseEngines(); } x += xVelocity; y += yVelocity; CalculateShootHeading(); if(shouldShoot) { ShootWeapons(); } UpdateWeapons(); This is CalculateShootHeading(). This is inside the enemy class so x and y are the enemy's x and y and the same with velocity. One output from my game log gives Player X = 2108, Player Y = -180.956, Player X velocity = 10.9949, Player Y Velocity = -6.26017, Enemy X = 1988.31, Enemy Y = -339.051, Enemy X velocity = 1.81666, Enemy Y velocity = -9.67762, 0 enemy projectiles. The output from the console tester is Bullet position = 2210.49, -239.313 and Player Position = 2210.49, -239.313. This doesn't make any sense. The only thing that could be different is the code or the input into my function in the game and I've checked that and I don't think that it is wrong as it's updated before this and never changed. float const bulletSpeed = 30.f; float const dx = playerX - x; float const dy = playerY - y; float const vx = playerXVelocity - xVelocity; float const vy = playerYVelocity - yVelocity; float const a = vx * vx + vy * vy - bulletSpeed * bulletSpeed; float const b = 2.f * (vx * dx + vy * dy); float const c = dx * dx + dy * dy; float const disc = b * b - 4.f * a * c; shouldShoot = false; if (disc >= 0.f) { float t0 = (-b - std::sqrt(disc)) / (2.f * a); float t1 = (-b + std::sqrt(disc)) / (2.f * a); if (t0 < 0.f || (t1 < t0 && t1 >= 0.f)) { t0 = t1; } if (t0 >= 0.f) { float shootx = vx + dx / t0; float shooty = vy + dy / t0; heading = std::atan2(shooty, shootx) * RAD2DEGREE; } shouldShoot = true; }

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• Dump an arbitrary object To Html String

  - by Michael Freidgeim

  For debugging purposes me and my collegue wanted to dump details of the arbitrary object, and created function that uses LINQPad Dump functionality (thanks to http://stackoverflow.com/a/6035014/52277 and original http://linqpad.uservoice.com/forums/18302-linqpad-feature-suggestions/suggestions/447166-make-dump-extension-method-available-in-visual-s discussion)    public static string DumpToHtmlString<T>(this T objectToSerialize)        {            string strHTML = "";            try            {                var writer = LINQPad.Util.CreateXhtmlWriter(true);                writer.Write(objectToSerialize);                strHTML = writer.ToString();            }            catch (Exception exc)            {                Debug.Assert(false, "Investigate why ?" + exc);            }            return strHTML;        }You will need to add the linqpad executable as a reference in your project.TO DO similar in plain text ,look at https://github.com/ServiceStack/ServiceStack.Text StringExtensions , e.g. JsonSerializer/CsvSerializer or http://objectdumper.codeplex.com/

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• A Better Way To Extract Date From DateTime Columns [SQL Server]

  - by Gopinath

  Quite a long ago I wrote about a SQL Server programming tip on how to extract date part from a DATETIME column. The post discusses about using of T SQL function convert() to get date part. One of the readers of the post, tipped me about a better way of extracting date part and here is the SQL query he sent to us SELECT DateAdd(day, DateDiff(day, 0, getdate()), 0); In clean way this query trims off time part from the DATETIME value. I rate this solution better than the one I wrote long ago as this one does not depend on any string operations. According the commenter, this method is faster compared to the other. What do you say? Thanks Yamo This article titled,A Better Way To Extract Date From DateTime Columns [SQL Server], was originally published at Tech Dreams. Grab our rss feed or fan us on Facebook to get updates from us.

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• "Final" Scheme REPL definitions: how to save them?

  - by Aeneas

  Is there a way to show and save all "final" definitions entered into a Scheme REPL into a text file? Say, if I have defined in the REPL: (define (increase x) (+ 1 x)) (define (multbytwo x) (* 3 x)) ; let us say this was an error (define (multbytwo x) (* 2 x)) I want to save this into an .scm-file with the content: (define (increase x) (+ 1 x)) (define (multbytwo x) (* 2 x)) i.e. the multbytwo function that got defined erraneously shall be "forgotten" due to re-definition. Is this possible?

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