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  • [XNA] Forming bounding box only around visible sprites

    - by nadalian
    Hi, this site has been really amazing for helping me with game development however I'm unable to find an answer for the following question (nor am I able to solve it on my own). I am trying to do rectangle collision in my game. My idea is to 1) get the original collision bounding rectangle 2) Transform the texture (pos/rot/scale) 3) Factor changes of item into a matrix and then use this matrix to change the original collision bounds of the item. However, my textures contain a lot of transparency, transparency that affect the overall height/width of the texture (I do this to maintain power of two dimensions). My problem: How to create a rectangle that forms dimensions which ignore transparency around the object. A picture is provided below: http://img51.imageshack.us/img51/4772/boundingbox.png

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  • JSON, Ajax login and signup form problem, critique

    - by user552828
    Here is my problem; indexdeneme2.php has two forms Sign up and Login form, and there is validation.js and login.js which are handling the AJAX and JSON response, there are validate.php and login.php which are my scripts for validating and login. When you sign up, it sends the data to validate.php perfectly and validate.php response with JSON perfectly, validate.js must show the error in #error div. validation.js works perfectly if it is working alone. I use same kind of script for login form. Login.php also works perfectly it responses with JSON and login.js shows the errors are appear in #errorlogin div. But this works when login.js works alone. When I try to work login.js and validate.js together, it is not working. validate.php and login.php works perfectly but login.js and validation.js are not working together. They can't handle the responses coming from php scripts. It is not showing the errors in #errorlogin and #error div. They intercept each other I guess. By the way if you can critique my login.php and validate.php I will be really appreciated. Thank you all. this is indexdeneme2.php <?php include('functions.php')?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>Untitled Document</title> <link rel="stylesheet" href="css/cssdeneme1.css" /> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js"></script> <script type="text/javascript" src="validation.js"></script> <script type="text/javascript" src="login.js"></script> <script type="text/javascript"> var RecaptchaOptions = { theme : 'custom', custom_theme_widget: 'recaptcha_widget' }; </script> </head> <body onload="document.signup.reset()"> <div id="topbar"> <div class="wrapper"> </div> </div> <div id="middlebar"> <div class="wrapper"> <div id="middleleft"> <div id="mainformsecondcover"> <div id="mainform"> <div id="formhead"> <div id="signup">Sign Up</div> </div> <form method="post" action="validate.php" id="myform" name="signup"> <div id="form"> <table border="0" cellpadding="0" cellspacing="1"> <tbody> <tr> <td class="formlabel"> <label for="name">First Name:</label> </td> <td class="forminput"> <input type="text" name="name" id="name" /> </td> </tr> <tr> <td class="formlabel"> <label for="lastname">Last Name:</label> </td> <td class="forminput"> <input type="text" name="surname" id="lastname" /> </td> </tr> <tr> <td class="formlabel"> <label for="email">Email:</label> </td> <td class="forminput"> <input type="text" name="email" id="email" /> </td> </tr> <tr> <td class="formlabel"> <label for="remail">Re-Enter Email:</label> </td> <td class="forminput"> <input type="text" name="remail" id="remail" /> </td> </tr> <tr> <td class="formlabel"> <label for="password">Password:</label> </td> <td class="forminput"> <input type="password" name="password" id="password" maxlength="16" /> </td> </tr> <tr> <td class="formlabel"> <label for="gender">I am:</label> </td> <td class="forminput"> <select name="gender" id="gender"> <option value="0" selected="selected">-Select Sex-</option> <option value="1">Male</option> <option value="2">Female</option> </select> </td> </tr> <tr> <td class="formlabel"> <label>My Birthday:</label> </td> <td class="forminput"> <select size="1" name="day"> <option value="0" selected="selected">Day</option> <?php formDay(); ?> </select>&nbsp; <select size="1" name="month"> <option value="0" selected="selected">Month</option> <option value="1">January</option> <option value="2">February</option> <option value="3">March</option> <option value="4">April</option> <option value="5">May</option> <option value="6">June</option> <option value="7">July</option> <option value="8">August</option> <option value="9">September</option> <option value="10">October</option> <option value="11">November</option> <option value="12">December</option> </select>&nbsp; <select size="1" name="year"> <option value="0" selected="selected">Year</option> <?php formYear(); ?> </select> </td> </tr> <tr> <td class="formlabel"> <label for="recaptcha_response_field">Security Check:</label> </td> </tr> </tbody> </table> <?php require_once('captchalib.php'); ?> </div> <div id="formbottom"> <div id="error"> </div> <div id="formbottomright"> <input type="submit" id="formbutton" value="Sign Up" /> <img id="loading" src="css/images/ajax-loader.gif" height="35" width="35" alt="Processing.." style="float:right; display:block" /> </div> </div> </form> </div> </div> </div> <div id="middleright"> <div id="loginform"> <form name="login" action="login.php" method="post" id="login"> <label for="username">Email:</label> <input type="text" name="emaillogin" /> <label for="password">Password:</label> <input type="password" name="passwordlogin" maxlength="16" /> <input type="submit" value="Login" /> <img id="loading2" src="css/images/ajax-loader.gif" height="35" width="35" alt="Processing.." style="float:right; display:block" /> </form> </div> <div id="errorlogin"></div> </div> </div> </div> <div id="bottombar"> <div class="wrapper"></div> </div> </body> </html> validation.js $(document).ready(function(){ $('#myform').submit(function(e) { register(); e.preventDefault(); }); }); function register() { hideshow('loading',1); error(0); $.ajax({ type: "POST", url: "validate.php", data: $('#myform').serialize(), dataType: "json", success: function(msg){ if(parseInt(msg.status)==1) { window.location=msg.txt; } else if(parseInt(msg.status)==0) { error(1,msg.txt); Recaptcha.reload(); } hideshow('loading',0); } }); } function hideshow(el,act) { if(act) $('#'+el).css('visibility','visible'); else $('#'+el).css('visibility','hidden'); } function error(act,txt) { hideshow('error',act); if(txt) $('#error').html(txt); } login.js $(document).ready(function(){ $('#login').submit(function(e) { login(); e.preventDefault(); }); }); function login() { error(2); $.ajax({ type: "POST", url: "login.php", data: $('#login').serialize(), dataType: "json", success: function(msg){ if(parseInt(msg.status)==3) { window.location=msg.txt; } else if(parseInt(msg.status)==2) { error(3,msg.txt); } } }); } function error(act,txt) { hideshow('error',act); if(txt) $('#errorlogin').html(txt); } login.php <?php session_start(); require("connect.php"); $email = $_POST['emaillogin']; $password = $_POST['passwordlogin']; $email = mysql_real_escape_string($email); $password = mysql_real_escape_string($password); if(empty($email)) { die('{status:2,txt:"Enter your email address."}'); } if(!filter_var($email, FILTER_VALIDATE_EMAIL)) { die('{status:2,txt:"Invalid email or password"}'); } if(empty($password)) { die('{status:2,txt:"Enter your password."}'); } if(strlen($password)<6 || strlen($password)>16) { die('{status:2,txt:"Invalid email or password"}'); } $query = "SELECT password, salt FROM users WHERE Email = '$email';"; $result = mysql_query($query); if(mysql_num_rows($result) < 1) //no such user exists { die('{status:2,txt:"Invalid email or password"}'); } $userData = mysql_fetch_array($result, MYSQL_ASSOC); $hash = hash('sha256', $userData['salt'] . hash('sha256', $password) ); if($hash != $userData['password']) //incorrect password { die('{status:2,txt:"Invalid email or password"}'); } //////////////////////////////////////////////////////////////////////////////////// if('{status:3}') { session_regenerate_id (); //this is a security measure $getMemDetails = "SELECT * FROM users WHERE Email = '$email'"; $link = mysql_query($getMemDetails); $member = mysql_fetch_row($link); $_SESSION['valid'] = 1; $_SESSION['userid'] = $member[0]; $_SESSION['name'] = $member[1]; session_write_close(); mysql_close($con); echo '{status:3,txt:"success.php"}'; } validate.php <?php $name = $_POST['name']; $surname = $_POST['surname']; $email = $_POST['email']; $remail = $_POST['remail']; $gender = $_POST['gender']; $bdate = $_POST['year'].'-'.$_POST['month'].'-'.$_POST['day']; $bday = $_POST['day']; $bmon = $_POST['month']; $byear = $_POST['year']; $cdate = date("Y-n-j"); $password = $_POST['password']; $hash = hash('sha256', $password); $regdate = date("Y-m-d"); function createSalt() { $string = md5(uniqid(rand(), true)); return substr($string, 0, 3); } $salt = createSalt(); $hash = hash('sha256', $salt . $hash); if(empty($name) || empty($surname) || empty($email) || empty($remail) || empty($password) ) { die('{status:0,txt:"All the fields are required"}'); } if(!preg_match('/^[A-Za-z\s ]+$/', $name)) { die('{status:0,txt:"Please check your name"}'); } if(!preg_match('/^[A-Za-z\s ]+$/', $surname)) { die('{status:0,txt:"Please check your last name"}'); } if($bdate > $cdate) { die('{status:0,txt:"Please check your birthday"}'); } if(!(int)$gender) { die('{status:0,txt:"You have to select your sex"}'); } if(!(int)$bday || !(int)$bmon || !(int)$byear) { die('{status:0,txt:"You have to fill in your birthday"}'); } if(!$email == $remail) { die('{status:0,txt:"Emails doesn&sbquo;t match"}'); } if(!filter_var($email, FILTER_VALIDATE_EMAIL)) { die('{status:0,txt:"Enter a valid email"}'); } if(strlen($password)<6 || strlen($password)>16) { die('{status:0,txt:"Password must be between 6-16 characters"}'); } if (!$_POST["recaptcha_challenge_field"]===$_POST["recaptcha_response_field"]) { die('{status:0,txt:"You entered incorrect security code"}'); } if('{status:1}') { require("connect.php"); function getRealIpAddr() { if (!empty($_SERVER['HTTP_CLIENT_IP'])) { $ip=$_SERVER['HTTP_CLIENT_IP']; } elseif (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) { $ip=$_SERVER['HTTP_X_FORWARDED_FOR']; } else { $ip=$_SERVER['REMOTE_ADDR']; } return $ip; } $rip = getRealIpAddr(); $ipn = inet_pton($rip); $checkuser = mysql_query("SELECT Email FROM users WHERE Email = '$email'"); $username_exist = mysql_num_rows($checkuser); if ( $username_exist !== 0 ) { mysql_close($con); die('{status:0,txt:"This email Address is already registered!"}'); } else { $query = "INSERT INTO users (name, surname, date, Email, Gender, password, salt, RegistrationDate, IP) VALUES ('$name', '$surname', '$bdate', '$email', '$gender', '$hash', '$salt', '$cdate', '$ipn')"; $link = mysql_query($query); if(!$link) { die('Becerilemedi: ' . mysql_error()); } else { mysql_close($con); echo '{status:1,txt:"afterreg.php"}'; } } } ?> css of indexdeneme2.php * { padding:0; margin:0; } #topbar { width:100%; height:50px; } .wrapper { margin:0 auto; width:1000px; height:100%; } #middlebar { width:100%; height:650px; } #middleleft { width:55%; float:left; height:650px; } #middleright { width:45%; float:right; height:650px; } #mainformsecondcover { width:404px; padding:0px; margin:0px; border:4px solid #59B; border-radius: 14px; -moz-border-radius: 14px; -webkit-border-radius: 14px; } #mainform { width:400px; border:2px solid #CCC; border-radius: 11px; -moz-border-radius: 11px; -webkit-border-radius: 11px; } #formhead { margin:7px; } #signup { margin-top:13px; margin-left:13px; margin-bottom:3px; color:#333; font-size:18px; font-family:"Lucida Sans Unicode", "Lucida Grande", sans-serif; font-weight:bold } #form { margin:7px; } #form table { margin:0px; width:380px; } #form table tr{ height:28px; } #form table td{ height:18px; } .formlabel { cursor:pointer; display:table-cell; text-align:right; font-size:12px; color:#000; font-weight:normal; vertical-align:middle; font-family:"Lucida Sans Unicode", "Lucida Grande", sans-serif; letter-spacing:1px; width:120px; height:37px; padding-right:5px; } .formlabel label{ cursor:pointer } .forminput input { width:240px; font-size:13px; padding:4px; } #recaptcha_image { width:300px; height:57px; border:2px solid #CCC; } #recaptcha_widget { margin-left:35px; } #securityinfo { font-size: 11px; line-height: 16px; } #formbottom { width:360px; min-height:45px; } #error { float:left; width:200px; border:1px solid #F00; margin-left:20px; margin-top:7px; text-align:center; color:#F00; font-family:"Lucida Sans Unicode", "Lucida Grande", sans-serif; font-size:11px; line-height:16px; padding:2px; visibility:hidden; } #errorlogin { float:left; width:200px; border:1px solid #F00; margin-left:20px; margin-top:7px; text-align:center; color:#F00; font-family:"Lucida Sans Unicode", "Lucida Grande", sans-serif; font-size:11px; line-height:16px; padding:2px; visibility:hidden; } #formbottomright { float:right; height:45px; width:115px; margin-left:5px; } #loading { visibility:hidden; } #loading2 { visibility:hidden; } #formbutton { display:block; font-size:14px; color:#FFF; background: #0b85c6; /* Old browsers */ background: -moz-linear-gradient(top, #0b85c6 0%, #59b 100%); /* FF3.6+ */ background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,#0b85c6), color-stop(100%,#59b)); /* Chrome,Safari4+ */ background: -webkit-linear-gradient(top, #0b85c6 0%,#59b 100%); /* Chrome10+,Safari5.1+ */ background: -o-linear-gradient(top, #0b85c6 0%,#59b 100%); /* Opera11.10+ */ background: -ms-linear-gradient(top, #0b85c6 0%,#59b 100%); /* IE10+ */ filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#0B85C6', endColorstr='#59B',GradientType=0 ); /* IE6-9 */ background: linear-gradient(top, #0b85c6 0%,#59b 100%); /* W3C */ font-family:"Lucida Sans Unicode", "Lucida Grande", sans-serif; height:26px; width:60px; margin:7px; text-align:center; padding-bottom:4px; padding-left:4px; padding-right:4px; float:left; margin-right:5px; } #bottombar { width:100%; height:50px; } {}

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  • Generate reasonable length license key with asymmetric encryption?

    - by starkos
    I've been looking at this all day. I probably should have walked away from it hours ago; I might be missing something obvious at this point. Short version: Is there a way to generate and boil down an asymmetrically encrypted hash to a reasonable number of unambiguous, human readable characters? Long version: I want to generate license keys for my software. I would like these keys to be of a reasonable length (25-36 characters) and easily read and entered by a human (so avoid ambiguous characters like the number 0 and the capital letter O). Finally--and this seems to be the kicker--I'd really like to use asymmetric encryption to make it more difficult to generate new keys. I've got the general approach: concatenate my information (user name, product version, a salt) into a string and generate a SHA1() hash from that, then encrypt the hash with my private key. On the client, build the SHA1() hash from the same information, then decrypt the license with the public key and see if I've got a match. Since this is a Mac app, I looked at AquaticPrime, but that generates a relatively large license file rather than a string. I can work with that if I must, but as a user I really like the convenience of a license key that I can read and print. I also looked at CocoaFob which does generate a key, but it is so long that I'd want to deliver it as a file anyway. I fooled around with OpenSSL for a while but couldn't come up with anything of a reasonable length. So...am I missing something obvious here? Is there a way to generate and boil down an asymmetrically encrypted hash to a reasonable number of unambiguous, human readable characters? I'm open to buying a solution. But I work on a number of different of platforms, so I'd want something portable. Everything I've looked at so far has been platform specific. Many, many thanks for a solution! PS - Yes, I know it will still be cracked. I'm trying to come up with something reasonable that, as a user, I would still find friendly.

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  • Best practices managing JavaScript on a single-page app

    - by seanmonstar
    With a single page app, where I change the hash and load and change only the content of the page, I'm trying to decide on how to manage the JavaScript that each "page" might need. I've already got a History module monitoring the location hash which could look like domain.com/#/company/about, and a Page class that will use XHR to get the content and insert it into the content area. function onHashChange(hash) { var skipCache = false; if(hash in noCacheList) { skipCache = true; } new Page(hash, skipCache).insert(); } // Page.js var _pageCache = {}; function Page(url, skipCache) { if(!skipCache && (url in _pageCache)) { return _pageCache[url]; } this.url = url; this.load(); } The cache should let pages that have already been loaded skip the XHR. I also am storing the content into a documentFragment, and then pulling the current content out of the document when I insert the new Page, so I the browser will only have to build the DOM for the fragment once. Skipping the cache could be desired if the page has time sensitive data. Here's what I need help deciding on: It's very likely that any of the pages that get loaded will have some of their own JavaScript to control the page. Like if the page will use Tabs, needs a slide show, has some sort of animation, has an ajax form, or what-have-you. What exactly is the best way to go around loading that JavaScript into the page? Include the script tags in the documentFragment I get back from the XHR? What if I need to skip the cache, and re-download the fragment. I feel the exact same JavaScript being called a second time might cause conflicts, like redeclaring the same variables. Would the better way be to attach the scripts to the head when grabbing the new Page? That would require the original page know all the assets that every other page might need. And besides knowing the best way to include everything, won't I need to worry about memory management, and possible leaks of loading so many different JavaScript bits into a single page instance?

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  • jQuery: resizing element cuts off parent's background

    - by Justine
    Hi, I've been trying to recreate an effect from this tutorial: http://jqueryfordesigners.com/jquery-look-tim-van-damme/ Unfortunately, I want a background image underneath and because of the resize going on in JavaScript, it gets resized and cut off as well, like so: http://dev.gentlecode.net/dotme/index-sample.html - you can view source there to check the HTML, but basic structure looks like this: <div class="page"> <div class="container"> div.header ul.nav div.main </div> </div> Here is my jQuery code: $('ul.nav').each(function() { var $links = $(this).find('a'), panelIds = $links.map(function() { return this.hash; }).get().join(","), $panels = $(panelIds), $panelWrapper = $panels.filter(':first').parent(), delay = 500; $panels.hide(); $links.click(function() { var $link = $(this), link = (this); if ($link.is('.current')) { return; } $links.removeClass('current'); $link.addClass('current'); $panels.animate({ opacity : 0 }, delay); $panelWrapper.animate({ height: 0 }, delay, function() { var height = $panels.hide().filter(link.hash).show().css('opacity', 1).outerHeight(); $panelWrapper.animate({ height: height }, delay); }); }); var showtab = window.location.hash ? '[hash=' + window.location.hash + ']' : ':first'; $links.filter(showtab).click(); }); In this example, panelWrapper is a div.main and it gets resized to fit the content of tabs. The background is applied to the div.page but because its child is getting resized, it resizes as well, cutting off the background image. It's hard to explain so please look at the link above to see what I mean. I guess what I'm trying to ask is: is there a way to resize an element without resizing its parent? I tried setting height and min-height of .page to 100% and 101% but that didn't work. I tried making the background image fixed, but nada. It also happens if I add the background to the body or even html. Help?

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  • Javascript terminates after trying to select data from an object passed to a function

    - by Silmaril89
    Here is my javascript: $(document).ready(function(){ var queries = getUrlVars(); $.get("mail3.php", { listid: queries["listid"], mindex: queries["mindex"] }, showData, 'html'); }); function showData(data) { var response = $(data).find("#mailing").html(); if (response == null) { $("#results").html("<h3>Server didn't respond, try again.</h3>"); } else if (response.length) { var old = $("#results").html(); old = old + "<br /><h3>" + response + "</h3>"; $("#results").html(old); var words = response.split(' '); words[2] = words[2] * 1; words[4] = words[4] * 1; if (words[2] < words[4]) { var queries = getUrlVars(); $.get("mail3.php", { listid: queries["listid"], mindex: words[2] }, function(data){showData(data);}, 'html'); } else { var done = $(data).find("#done").html(); old = old + "<br />" + done; $("#results").html(old); } } else { $("#results").html("<h3>Server responded with an empty reply, try again.</h3>"); } } function getUrlVars() { var vars = [], hash; var hashes = window.location.href.slice(window.location.href.indexOf('?') + 1).split('&'); for (var i = 0; i < hashes.length; i++) { hash = hashes[i].split('='); vars.push(hash[0]); vars[hash[0]] = hash[1]; } return vars; } After the first line in showData: var response = $(data).find("#mailing").html(); the javascript stops. If I put an alert before it, the alert pops up, after it, it doesn't pop up. There must be something wrong with using $(data), but why? Any ideas would be appreciated.

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  • Caching factory design

    - by max
    I have a factory class XFactory that creates objects of class X. Instances of X are very large, so the main purpose of the factory is to cache them, as transparently to the client code as possible. Objects of class X are immutable, so the following code seems reasonable: # module xfactory.py import x class XFactory: _registry = {} def get_x(self, arg1, arg2, use_cache = True): if use_cache: hash_id = hash((arg1, arg2)) if hash_id in _registry: return _registry[hash_id] obj = x.X(arg1, arg2) _registry[hash_id] = obj return obj # module x.py class X: # ... Is it a good pattern? (I know it's not the actual Factory Pattern.) Is there anything I should change? Now, I find that sometimes I want to cache X objects to disk. I'll use pickle for that purpose, and store as values in the _registry the filenames of the pickled objects instead of references to the objects. Of course, _registry itself would have to be stored persistently (perhaps in a pickle file of its own, in a text file, in a database, or simply by giving pickle files the filenames that contain hash_id). Except now the validity of the cached object depends not only on the parameters passed to get_x(), but also on the version of the code that created these objects. Strictly speaking, even a memory-cached object could become invalid if someone modifies x.py or any of its dependencies, and reloads it while the program is running. So far I ignored this danger since it seems unlikely for my application. But I certainly cannot ignore it when my objects are cached to persistent storage. What can I do? I suppose I could make the hash_id more robust by calculating hash of a tuple that contains arguments arg1 and arg2, as well as the filename and last modified date for x.py and every module and data file that it (recursively) depends on. To help delete cache files that won't ever be useful again, I'd add to the _registry the unhashed representation of the modified dates for each record. But even this solution isn't 100% safe since theoretically someone might load a module dynamically, and I wouldn't know about it from statically analyzing the source code. If I go all out and assume every file in the project is a dependency, the mechanism will still break if some module grabs data from an external website, etc.). In addition, the frequency of changes in x.py and its dependencies is quite high, leading to heavy cache invalidation. Thus, I figured I might as well give up some safety, and only invalidate the cache only when there is an obvious mismatch. This means that class X would have a class-level cache validation identifier that should be changed whenever the developer believes a change happened that should invalidate the cache. (With multiple developers, a separate invalidation identifier is required for each.) This identifier is hashed along with arg1 and arg2 and becomes part of the hash keys stored in _registry. Since developers may forget to update the validation identifier or not realize that they invalidated existing cache, it would seem better to add another validation mechanism: class X can have a method that returns all the known "traits" of X. For instance, if X is a table, I might add the names of all the columns. The hash calculation will include the traits as well. I can write this code, but I am afraid that I'm missing something important; and I'm also wondering if perhaps there's a framework or package that can do all of this stuff already. Ideally, I'd like to combine in-memory and disk-based caching.

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  • Good Open souce game engines for making MMO game

    - by Call Me Dummy
    I am interested in making a MMO game but I am not sure where to start. I am looking for an open source game engine which is simple to use and allows me to concentrate on the game design and architecture. I have some basic C,C++,C# knowledge. After lots of searching in google I was going to start out with Ogre3D but soon realized that it is a rendering engine and does not include physics engine. I have not tried it yet since in many forums it says they don't have a good documentation. So is there any good open source game engine good for fast game developing ? Some key features I want include basic requirements like collision detection, object to object collision detection, physics etc.

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  • Hadron Collider – Can it unveil the hidden secrets of universe?

    - by samsudeen
    Scientist at  European Centre for Nuclear Research (CERN) today successfully simulated the Big Bang experiment finally by producing  the world’s first high-energy particle collision.This is achieved through the collision of two protons with a total energy of  around seven trillion electron volts sending sub-particles spread through in every direction.   The experiment is conducted successfully around the  European Centre for Nuclear Research (CERN) which is under 100 metres below the Franco-Swiss border. This is said to be the biggest experiment in terms on the investment (around $7 billion) and the scientific importance. This will lead to a new era of science and could change the theories about the origin of universe. You can find  more videos about the experiment at the LHC Videos Join us on Facebook to read all our stories right inside your Facebook news feed.

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  • Silverlight Cream for March 15, 2011 -- #1061

    - by Dave Campbell
    In this Issue: Peter Kuhn, Emil Stoychev, Viktor Larsson(-2-), Kevin Hoffman, Rudi Grobler, WindowsPhoneGeek, Jesse Liberty(-2-), and Martin Krüger. Above the Fold: Silverlight: "Image comparison using a GridSplitter" Martin Krüger WP7: "Using WP7 accent color effectively" Viktor Larsson XNA: "XNA for Silverlight developers: Part 7 - Collision detection" Peter Kuhn From SilverlightCream.com: XNA for Silverlight developers: Part 7 - Collision detection Peter Kuhn has part 7 of his XNA for Silverlight devs tutorial series up at SilverlightShow... discussing Collision detection... something you need to get your head around if you're going to do a game. Interview with John Papa about the upcoming MIX11 event and the Open Source Fest Emil Stoychev of SilverlightShow reverses the roles with John Papa and interviews John on this MIX11 and Open Source Fest discussion they had at the MVP Summit Debugging Videos or Camera in WP7 Viktor Larsson has a quick post up on the 3 ways of debugging a WP7 app and why and under what circumstances you should change debug method. Using WP7 accent color effectively Viktor Larsson's next post is about the 10 accent colors available on WP7 devices. He shows how to make best use of that capability in XAML and runtime code. WP7 for iPhone and Android Developers - Hardware and Device Services Kevin Hoffman's part 4 of a 12-part tutorial series at SilverlightShow on WP7 for iPhone/Android devs is up ... this oe concentrates on Hardware and Device Services... Launchers/Choosers/Sensors. How to publish WP7 applications if you live in the Middle-east & Africa region Rudi Grobler has a short post up on a legit way to publish WP7 apps if you are in the MEA region. Creating WP7 Custom Theme – Sample Theme Implementation WindowsPhoneGeek has a new post up and he's starting a series of 3 articles on Creating Wp7 Custom Themes... first up is this tutorial on Basic Theme Implementation... and use it as well. From Android to Windows Phone For "Windows Phone from Scratch #43", Jesse Liberty begins a series on moving apps from Android to WP7, beginning with a tip calculating program. Yet Another Podcast #28–Jeremy Likness Jesse Liberty's next post is his "Yet Another Podcast #28" with Jeremy Likness this time around... the list of all things fun that Jeremy's involved in is getting long... should be a good podcast! Image comparison using a GridSplitter Martin Krüger posted a cool 'Clip Splitter' for comparing images, and what a great set of example images he's using... pretty darn cool lining them up with a grid-splitter. Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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  • Best way of storing voxels

    - by opiop65
    This should be a pretty easy question to answer, and I'm not looking for how to store the voxels data wise, I'm looking for the theory. Currently, my voxel engine has no global list of tiles. Each chunk has it's own list, and its hard to do things like collision detection or anything that may use tiles that are outside of its own chunk. I recently worked on procedural terrain with a non voxel engine. Now, I want to start using heightmaps in my voxel engine. But, I have a problem. If each chunk has its own list, then it will be pretty difficult to implement the heightmaps. My real question is, is should I store a global list of voxels independent of the chunks? And then I can just easily perform collision detection and terrain generation. However, it would probably be harder to do things such as frustum culling. So how should I store them?

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  • Separating physics and game logic from UI code

    - by futlib
    I'm working on a simple block-based puzzle game. The game play consists pretty much of moving blocks around in the game area, so it's a trivial physics simulation. My implementation, however, is in my opinion far from ideal and I'm wondering if you can give me any pointers on how to do it better. I've split the code up into two areas: Game logic and UI, as I did with a lot of puzzle games: The game logic is responsible for the general rules of the game (e.g. the formal rule system in chess) The UI displays the game area and pieces (e.g. chess board and pieces) and is responsible for animations (e.g. animated movement of chess pieces) The game logic represents the game state as a logical grid, where each unit is one cell's width/height on the grid. So for a grid of width 6, you can move a block of width 2 four times until it collides with the boundary. The UI takes this grid, and draws it by converting logical sizes into pixel sizes (that is, multiplies it by a constant). However, since the game has hardly any game logic, my game logic layer [1] doesn't have much to do except collision detection. Here's how it works: Player starts to drag a piece UI asks game logic for the legal movement area of that piece and lets the player drag it within that area Player lets go of a piece UI snaps the piece to the grid (so that it is at a valid logical position) UI tells game logic the new logical position (via mutator methods, which I'd rather avoid) I'm not quite happy with that: I'm writing unit tests for my game logic layer, but not the UI, and it turned out all the tricky code is in the UI: Stopping the piece from colliding with others or the boundary and snapping it to the grid. I don't like the fact that the UI tells the game logic about the new state, I would rather have it call a movePieceLeft() method or something like that, as in my other games, but I didn't get far with that approach, because the game logic knows nothing about the dragging and snapping that's possible in the UI. I think the best thing to do would be to get rid of my game logic layer and implement a physics layer instead. I've got a few questions regarding that: Is such a physics layer common, or is it more typical to have the game logic layer do this? Would the snapping to grid and piece dragging code belong to the UI or the physics layer? Would such a physics layer typically work with pixel sizes or with some kind of logical unit, like my game logic layer? I've seen event-based collision detection in a game's code base once, that is, the player would just drag the piece, the UI would render that obediently and notify the physics system, and the physics system would call a onCollision() method on the piece once a collision is detected. What is more common? This approach or asking for the legal movement area first? [1] layer is probably not the right word for what I mean, but subsystem sounds overblown and class is misguiding, because each layer can consist of several classes.

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  • Why doesn't my GameMaker step event work?

    - by exceltior
    So I want to make some kind of floor that which the player when walks in gets his movement reduced but im having thousand of different issues implementing this since it doesnt appear to do anything ... So i have tried different way: 1 - I have tried Step Event which had the following script: if keyboard_check(ord('A')) { player.x = -5; } if keyboard_check(ord('D')) { player.x = -5; } if keyboard_check(ord('W')) { player.x = -5; } if keyboard_check(ord('S')) { player.x = -5; } 2 - I have tried a Collision Event with the same code 3- I have tried a Step event with collision detection on a script None of these options seem to work at all ... Can you help me?

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  • How do engines avoid "Phase Lock" (multiple objects in same location) in a Physics Engine?

    - by C0M37
    Let me explain Phase Lock first: When two objects of non zero mass occupy the same space but have zero energy (no velocity). Do they bump forever with zero velocity resolution vectors or do they just stay locked together until an outside force interacts? In my home brewed engine, I realized that if I loaded a character into a tree and moved them, they would signal a collision and hop back to their original spot. I suppose I could fix this by implementing impulses in the event of a collision instead of just jumping back to the last spot I was in (my implementation kind of sucks). But while I make my engine more robust, I'm just curious on how most other physics engines handle this case. Do objects that start in the same spot with no movement speed just shoot out from each other in a random direction? Or do they sit there until something happens? Which option is generally the best approach?

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  • Making more complicated systems(entity-component-system model question)

    - by winch
    I'm using a model where entities are collections of components and components are just data. All the logic goes into systems which operate on components. Making basic systems(for Rendering and handling collision) was easy. But how do I do more compilcated systems? For example, in a CollisionSystem I can check if entity A collides with entity B. I have this code in CollisionSystem for checking if B damages A: if(collides(a, b)) { HealthComponent* hc = a->get<HealthComponent(); hc.reduceHealth(b->get<DamageComponent>()->getDamage()); But I feel that this code shouldn't belong to Collision system. Where should code like this be and which additional systems should I create to make this code generic?

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  • How to perform efficient 2D picking in HTML5?

    - by jSepia
    I'm currently using an R-Tree for both picking and collision testing. Each entity on screen has a bounding box for collisions and a separate one for picking. Since entities may change position very frequently, both trees must be updated/reordered once per frame. While this is very efficient for collisions, because the tree is used in hundreds of collision queries every frame, I'm finding it too costly for picking, because it only gets queried when the user clicks, thus leading to a lot of wasted tree updates. What would be a more efficient way to implement picking without as much overhead?

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  • How can I get my meshes to work with Bullet Physics?

    - by Molmasepic
    The problem is that I'm trying to use my meshes with Bullet Physics for the collision part of my game. When I attempted doing this method with my GLM(model loading library by nate robins) model, I get a segmentation fault in the debug, so I figured that it doesnt like the coordinate variables of the model. If i use blender to export my model as a collision file, what type of file should I use? I have heard of a .bullet exporter, but i dont know hot to integrate this python script into my Blender 2.5 program.

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  • How to implement the light trails for a tron game?

    - by Link
    Well I was creating a TRON style game, but had an issue with creating the actual light trails for the game. What I'm doing currently is I have an array the same size as my window in pixel size, implemented like this: int* collision[800][600]; Then when the bike goes on a certain pixel, it is marked with a 1 for traveled on. However what is the most efficient way to create a working light trail display? I tried to do something like this: int i, j; for(i=0; i<800; i++) for(j=0; j<600; j++) if(*collision[i][j] == 1) Image::applySurface(i, j, trailSurface, gameScreen); But it isn't working properly? It just fills the whole screen with a sprite instead. Whats a better/faster/working way to do this?

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  • Sprite rotation

    - by Kipras
    I'm using OpenGL and people suggest using glRotate for sprite rotation, but I find that strange. My problem with it is that it rotates the whole matrix, which sort of screws up all my collision detection and so on and so forth. Imagine I had a sprite at position (100, 100) and in position (100, 200) is an obstacle and the sprite's facing it. I rotate the sprite away from the obstacle and when move upwards my y axis, even though the projection shows like it's going away from the obstacle, the sprite will intersect it. So I don't see another way of a rotating a sprite and not screwing up all collision detection other than doing mathematical operations on the image itself. Am I right or am I missing something?

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  • What Java class should I use to represent a Vector?

    - by user8363
    Does Java have a built-in Vector class suitable for handling collision detection / response? It should have methods like subtract(Vector v), normalize(), dotProduct(Vector v), ... It seems logical to use java.awt.Rectangle and java.awt.Polygon to calculate collisions. Would I be right to use these classes for this purpose? I understand collision detection; I'm only wondering what approach to it is idiomatic in Java. I'm new to the language and to application development in general.

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  • Instantiating a list of parameterized types, making beter use of Generics and Linq

    - by DanO
    I'm hashing a file with one or more hash algorithms. When I tried to parametrize which hash types I want, it got a lot messier than I was hoping. I think I'm missing a chance to make better use of generics or LINQ. I also don't like that I have to use a Type[] as the parameter instead of limiting it to a more specific set of type (HashAlgorithm descendants), I'd like to specify types as the parameter and let this method do the constructing, but maybe this would look better if I had the caller new-up instances of HashAlgorithm to pass in? public List<string> ComputeMultipleHashesOnFile(string filename, Type[] hashClassTypes) { var hashClassInstances = new List<HashAlgorithm>(); var cryptoStreams = new List<CryptoStream>(); FileStream fs = File.OpenRead(filename); Stream cryptoStream = fs; foreach (var hashClassType in hashClassTypes) { object obj = Activator.CreateInstance(hashClassType); var cs = new CryptoStream(cryptoStream, (HashAlgorithm)obj, CryptoStreamMode.Read); hashClassInstances.Add((HashAlgorithm)obj); cryptoStreams.Add(cs); cryptoStream = cs; } CryptoStream cs1 = cryptoStreams.Last(); byte[] scratch = new byte[1 << 16]; int bytesRead; do { bytesRead = cs1.Read(scratch, 0, scratch.Length); } while (bytesRead > 0); foreach (var stream in cryptoStreams) { stream.Close(); } foreach (var hashClassInstance in hashClassInstances) { Console.WriteLine("{0} hash = {1}", hashClassInstance.ToString(), HexStr(hashClassInstance.Hash).ToLower()); } }

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  • Can I convert an ASCII MD5 hashed password into a Unicode MD5 hashed password?

    - by Jimmy Moo Moo
    Hello, I'm looking for help to convert an ASCII MD5 hashed password into a Unicode MD5 hashed password? For example, I'll use the string "password" . When it's converted to an ascii byte array, I get a base64 encoded hash of X03MO1qnZdYdgyfeuILPmQ== When it's converted into a unicode byte array, I get a base64 encoded hash of sIHb6F4ew//D1OfQInQAzQ== All my passwords are stored in an md5 hash that was applied to an ascii byte array, but I'm trying to migrate my application's user data to a system that stores password in an md5 hash that is applied a unicode byte array. In case it's not clear, with the following C#code: var passwordBytes = Encoding.ASCII.GetBytes("password"); var hashAlgorithm = HashAlgorithm.Create("MD5"); var hashBytes = hashAlgorithm.ComputeHash(passwordBytes); My current system uses this, but the system I'm moving to has a diff first time. It usese Encoding.Unicode.GetBytes. Does anybody know how I can convert my passwords? From X03MO1qnZdYdgyfeuILPmQ== into sIHb6F4ew//D1OfQInQAzQ== I'm guessing the answer is that I can't.. the encoding is being done before the hashing, but I thought I'd inquire the bright minds of stackoverflow and see if anybody has a way.

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  • How to avoid saving a blank model which attributes can be blank

    - by auralbee
    Hello people, I have two models with a HABTM association, let´s say book and author. class Book has_and_belongs_to_many :authors end class Author has_and_belongs_to_many :books end The author has a set of attributes (e.g. first-name,last-name,age) that can all be blank (see validation). validates_length_of :first_name, :maximum => 255, :allow_blank => true, :allow_nil => false In the books_controller, I do the following to append all authors to a book in one step: @book = Book.new(params[:book]) @book.authors.build(params[:book][:authors].values) My question: What would be the easiest way to avoid the saving of authors which fields are all blank to prevent too much "noise" in the database? At the moment, I do the following: validate :must_have_some_data def must_have_some_data empty = true hash = self.attributes hash.delete("created_at") hash.delete("updated_at") hash.each_value do |value| empty = false if value.present? end if (empty) errors.add_to_base("Fields do not contain any data.") end end Maybe there is an more elegant, Rails-like way to do that. Thanks.

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  • rails inverting to_xml and getting the original model

    - by djacobs7
    I did this: [User.first, User.last].to_xml and got this: <users type="array"> <user> <created-at type="datetime">2010-03-16T06:40:51Z</created-at> <id type="integer">3</id> <password-hash></password-hash> <salt></salt> <updated-at type="datetime">2010-03-16T06:40:51Z</updated-at> <username nil="true"></username> </user> <user> <created-at type="datetime">2010-03-23T03:58:15Z</created-at> <id type="integer">7</id> <password-hash></password-hash> <salt></salt> <tutorial-state nil="true"></tutorial-state> <updated-at type="datetime">2010-03-23T03:58:15Z</updated-at> <username nil="true"></username> </user> </users> How can I take that string of xml and invert it to get the original activerecord objects back?

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  • How to code a URL shortener?

    - by marco92w
    I want to create a URL shortener service where you can write a long URL into an input field and the service shortens the URL to "http://www.example.org/abcdef". Instead of "abcdef" there can be any other string with six characters containing a-z, A-Z and 0-9. That makes 56 trillion possible strings. My approach: I have a database table with three columns: id, integer, auto-increment long, string, the long URL the user entered short, string, the shortened URL (or just the six characters) I would then insert the long URL into the table. Then I would select the auto-increment value for "id" and build a hash of it. This hash should then be inserted as "short". But what sort of hash should I build? Hash algorithms like MD5 create too long strings. I don't use these algorithms, I think. A self-built algorithm will work, too. My idea: For "http://www.google.de/" I get the auto-increment id 239472. Then I do the following steps: short = ''; if divisible by 2, add "a"+the result to short if divisible by 3, add "b"+the result to short ... until I have divisors for a-z and A-Z. That could be repeated until the number isn't divisible any more. Do you think this is a good approach? Do you have a better idea?

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