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  • Problem creating a webpage in OOP pattern?

    - by Starx
    I want to develop a website in OOP pattern, but I am stuck in a point whether I need to inherit from multiple classes. For example I have a main class "index" this class has several methods which need to inherited from other classes and I have created seperate classes for it like class "banner", class "content", class "footer" Not only this but class "content" has several methods to be inherited from other classes like class "gallery", class "news", etc I found out that multiple inheritance is not allowed, and using interface I cannot write codes in its methods, so how can i achieve a solution for this problem.

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  • php $_SESSION[document_root] too far down the tree

    - by Idealflip
    Hi, I have multiple sub-domains within the document_root. And multiple folders/classes within those sub-domain folders. I need something that will help me with my include_once paths, but $_SESSION[DOCUMENT_ROOT] goes too far down. And if I were to use this, and transfer the website folder later, all my include_once paths will/might break. Hope my question is clear... Any recommendations?

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  • Drupal User Permissions, Only Allow Specific Users to Edit Specific Pages

    - by jordanstephens
    I know I can set up a role to allow user's to only edit their own pages, then go mark the appropriate pages to be authored by the appropriate user. But then I run into multiple users per page problems. Is there any way that you can explicitly only allow a user to edit certain (perhaps multiple) pages, while accounting for overlap in the case that more than one user may be allowed to edit the same page? Thank you

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  • @Unique doesn't have any effect in DataNucleus w/ NeoDatis

    - by David Parks
    Using JDO / DataNucleus / NeoDatis datastore I added @Unique to a field of a persistable object, however I am allowed to create multiple objects which violate the unique constraint. The docs for DataNucleus/NeoDatis suggest that Unique fields are supported. @PersistenceCapable public class User { @Persistent @Unique private String username; //... } If I add multiple objects to the DB with the same username there's no problem doing so. :(

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  • Getting jQuery to recognise .change() in IE

    - by Philip Morton
    I'm using jQuery to hide and show elements when a radio button group is altered/clicked. It works fine in browsers like Firefox, but in IE 6 and 7, the action only occurs when the user then clicks somewhere else on the page. To elaborate, when you load the page, everything looks fine. In Firefox, if you click a radio button, one table row is hidden and the other one is shown immediately. However, in IE 6 and 7, you click the radio button and nothing will happen until you click somewhere on the page. Only then does IE redraw the page, hiding and showing the relevant elements. Here's the jQuery I'm using: $(document).ready(function(){ $(".hiddenOnLoad").hide(); $("#viewByOrg").change(function () { $(".visibleOnLoad").show(); $(".hiddenOnLoad").hide(); }); $("#viewByProduct").change(function () { $(".visibleOnLoad").hide(); $(".hiddenOnLoad").show(); }); }); Here's the part of the XHTML that it affects. Apologies if it's not very clean, but the whole page does validate as XHTML 1.0 Strict: <tr> <td>View by:</td> <td> <p> <input type="radio" name="viewBy" id="viewByOrg" value="organisation" checked="checked"/> Organisation </p> <p> <input type="radio" name="viewBy" id="viewByProduct" value="product"/> Product </p> </td> </tr> <tr class="visibleOnLoad"> <td>Organisation:</td> <td> <select name="organisation" id="organisation" multiple="multiple" size="10"> <option value="1">Option 1</option> <option value="2">Option 2</option> </select> </td> </tr> <tr class="hiddenOnLoad"> <td>Product:</td> <td> <select name="product" id="product" multiple="multiple" size="10"> <option value="1">Option 1</option> <option value="2">Option 2</option> </select> </td> </tr> If anyone has any ideas why this is happening and how to fix it, they would be very much appreciated!

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  • Is Perforce's C++ P4API thread-safe?

    - by Scott Bilas
    Simple question - is the C++ API provided by Perforce thread-safe? There is no mention of it in the documentation. By "thread-safe" I mean for server requests from the client. Obviously there will be issues if I have multiple threads trying to set client names and such on the same connection. But given a single connection object, can I have multiple threads fetching changelists, getting status, translating files through a p4 map, etc.?

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  • Locking individual elements in a static collection?

    - by user638474
    I have a static collection of objects that will be frequently updated from multiple threads. Is it possible to lock individual objects in a collection instead of locking the entire collection so that only threads trying to access the same object in the collection would get blocked instead of every thread? If there is a better way to update objects in a collection from multiple threads, I'm all ears.

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  • How to set the option value through model

    - by user281180
    I need to have the value for the option in the following: I have created my select as follows: <select id="fromSelectBox" multiple="multiple" > <% foreach (var item in Model.Projects) { %> <option><%=Html.Encode(item.Text)%></option> <%} %> </select> How do I set the value of the option using the value in the model which s item.ID?

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  • Sharing assembly code between WPF, Silverlight and Windows Phone: quite impractical for big projects !

    - by user310291
    It is said here: http://blogs.msdn.com/b/mikeormond/archive/2010/12/09/writing-cross-platform-xaml-applications.aspx Within Visual Studio, if you add files to the project via “Add Existing Item”, and select the “Add As Link” option you can work on the same file from multiple projects. Oh my I'm on a project which have multiple countries, brands, components layers and each time I will add a file you want me to "Add as Link" ? This is a nightmare maintenance ! Is there any other solutions ?

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  • Click to select from a list of tags in jQuery

    - by Michael Doornbos
    I'm struggling to find a tag selection UI for a rails app. Ideally it would be something like the selection here on Stackoverflow, or on Delicious or Digg. I want users to be able to select multiple tags with a single click. We're already using jQuery, so it makes sense to use something that takes advantage of that. I've used the selection ui in jQuery and I'm not thrilled about having users need to hold down ctrl to select multiple tags.

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  • How to use an excel data-set for a multi-line ggplot in R?

    - by user1299887
    I have a data set in excel that I am trying to create a multiple line plot with on R. The data set contains 7 food groups and the calories consumed daily associated to the groups. As well, there is that set of data over 38 years (from 1970-2008) and I am attempting to use this data set to create a multiple line plot on R. I have tried for hours on end but can not seem to get R to recognize the variables within the data set.

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  • Programme d'étude sur le C++ bas niveau n° 3 : la Pile, un article d'Alex Darby traduit par ram-0000

    L'objectif de cette série d'articles d'Alex Darby sur la programmation « bas-niveau » est de permettre aux développeurs ayant déjà des connaissances de la programmation C++ de mieux comprendre comment ses programmes sont exécutés en pratique. Ce troisième article explique le rôle et le fonctionnement de la Pile, son usage lors de l'appel d'une fonction, la gestion des variables locales ainsi que la gestion de la valeur de retour d'une fonction. Programme d'étude sur le C++ bas niveau n° 3 : la Pile Connaissiez-vous bien le fonctionnement de la Pile et des appels de fonctions ?

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  • Coherence Based WebLogic Server Session Management

    - by [email protected]
    Specifications Supported Configurations WebLogic Server 10.3.2( or 10.3.1 ) Coherence 3.5.2/463 If you use other verion above, then please check the following matrix:   WebLogic Server 9.2 MP1 Weblogic Server 10.3 WebLogic Smart Update Patch ID: AJQB Patch ID: 6W2W Minimum Coherence Release Level/MetaLink Patch ID 3.4.2 Patch 2-Patch ID:8429415 3.4.2 Patch6-Patch ID:11399293 Environment Variables %COHERENCE_HOME%: coherence installation directory %DOMAIN_HOME%: weblogic domain foler. Instructions We Will create to weblogic domains: domain_a, domain_b. To configure those domains with coherence-based session management . Then the changings of session variable value in one domain will propagate to another domain. Main Steps WebLogic Server create domain_a The process is ignored copy %COHERENCE_HOME%\lib\coherence.jar to %DOMAIN_HOME%\lib startup domain deploy %COHERENCE_HOME%\lib\coherence-web-spi.war as a Shared Library repeat step 1~4 at domain_b Coherence duplicate %COHERENCE_HOME%\bin\cache-server.cmd at the same folder and rename it to web-cache-server.cmd modify web-cache-server.cmd java -server -Xms512m -Xmx512m -cp %coherence_home%/lib/coherence.jar;%coherence_home%/lib/coherence-web-spi.war -Dtangosol.coherence.management.remote=true -Dtangosol.coherence.cacheconfig=WEB-INF/classes/session-cache-config.xml -Dtangosol.coherence.session.localstorage=true com.tangosol.net.DefaultCacheServer startup web-cache-server.cmd Testing develop a web app  with OEPE or JDeveloper and implment functions: changing, viewing, listing  session variables. ( or download sample codes here ) modify weblogic.xml with following content: <?xml version="1.0" encoding="UTF-8"?> <wls:weblogic-web-app xmlns:wls=http://xmlns.oracle.com/weblogic/weblogic-web-app xmlns:xsi=http://www.w3.org/2001/XMLSchema-instance xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd http://xmlns.oracle.com/weblogic/weblogic-web-app http://xmlns.oracle.com/weblogic/weblogic-web-app/1.0/weblogic-web-app.xsd"> <wls:weblogic-version>10.3.2</wls:weblogic-version> <wls:context-root>CoherenceWeb</wls:context-root> <wls:library-ref> <wls:library-name>coherence-web-spi</wls:library-name> <wls:specification-version>1.0.0.0</wls:specification-version> <wls:exact-match>true</wls:exact-match> </wls:library-ref> </wls:weblogic-web-app> deploy the web app to domain_a and domain_b change session varaible vlaue at domain_a and check whethe if changed at domain_b References Using Oracle Coherence*Web 3.4.2 with Oracle WebLogic Server 10gR3 Oracle Coherence*Web 3.4.2 with Oracle WebLogic Server 10gR3

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  • Improving CSS With .LESS

    Cascading Style Sheets, or CSS, is a syntax used to describe the look and feel of the elements in a web page. CSS allows a web developer to separate the document content - the HTML, text, and images - from the presentation of that content. Such separation makes the markup in a page easier to read, understand, and update; it can result in reduced bandwidth as the style information can be specified in a separate file and cached by the browser; and makes site-wide changes easier to apply. For a great example of the flexibility and power of CSS, check out CSS Zen Garden. This website has a single page with fixed markup, but allows web developers from around the world to submit CSS rules to define alternate presentation information. Unfortunately, certain aspects of CSS's syntax leave a bit to be desired. Many style sheets include repeated styling information because CSS does not allow the use of variables. Such repetition makes the resulting style sheet lengthier and harder to read; it results in more rules that need to be changed when the website is redesigned to use a new primary color. Specifying inherited CSS rules, such as indicating that a elements (i.e., hyperlinks) in h1 elements should not be underlined, requires creating a single selector name, like h1 a. Ideally, CSS would allow for nested rules, enabling you to define the a rules directly within the h1 rules. .LESS is a free, open-source port of Ruby's LESS library. LESS (and .LESS, by extension) is a parser that allows web developers to create style sheets using new and improved language features, including variables, operations, mixins, and nested rules. Behind the scenes, .LESS converts the enhanced CSS rules into standard CSS rules. This conversion can happen automatically and on-demand through the use of an HTTP Handler, or done manually as part of the build process. Moreover, .LESS can be configured to automatically minify the resulting CSS, saving bandwidth and making the end user's experience a snappier one. This article shows how to get started using .LESS in your ASP.NET websites. Read on to learn more! Read More >

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  • Improving CSS With .LESS

    Improve your CSS skills using .LESS, a free, open-source port of Ruby's LESS library. LESS (and .LESS, by extension) is a parser that allows web developers to create style sheets using new and improved language features, including variables, operations, mix-ins, and nested rules.

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  • Improving CSS With .LESS

    Cascading Style Sheets, or CSS, is a syntax used to describe the look and feel of the elements in a web page. CSS allows a web developer to separate the document content - the HTML, text, and images - from the presentation of that content. Such separation makes the markup in a page easier to read, understand, and update; it can result in reduced bandwidth as the style information can be specified in a separate file and cached by the browser; and makes site-wide changes easier to apply. For a great example of the flexibility and power of CSS, check out CSS Zen Garden. This website has a single page with fixed markup, but allows web developers from around the world to submit CSS rules to define alternate presentation information. Unfortunately, certain aspects of CSS's syntax leave a bit to be desired. Many style sheets include repeated styling information because CSS does not allow the use of variables. Such repetition makes the resulting style sheet lengthier and harder to read; it results in more rules that need to be changed when the website is redesigned to use a new primary color. Specifying inherited CSS rules, such as indicating that a elements (i.e., hyperlinks) in h1 elements should not be underlined, requires creating a single selector name, like h1 a. Ideally, CSS would allow for nested rules, enabling you to define the a rules directly within the h1 rules. .LESS is a free, open-source port of Ruby's LESS library. LESS (and .LESS, by extension) is a parser that allows web developers to create style sheets using new and improved language features, including variables, operations, mixins, and nested rules. Behind the scenes, .LESS converts the enhanced CSS rules into standard CSS rules. This conversion can happen automatically and on-demand through the use of an HTTP Handler, or done manually as part of the build process. Moreover, .LESS can be configured to automatically minify the resulting CSS, saving bandwidth and making the end user's experience a snappier one. This article shows how to get started using .LESS in your ASP.NET websites. Read on to learn more! Read More >

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  • VS 2010 Debugger Improvements (BreakPoints, DataTips, Import/Export)

    - by ScottGu
    This is the twenty-first in a series of blog posts I’m doing on the VS 2010 and .NET 4 release.  Today’s blog post covers a few of the nice usability improvements coming with the VS 2010 debugger.  The VS 2010 debugger has a ton of great new capabilities.  Features like Intellitrace (aka historical debugging), the new parallel/multithreaded debugging capabilities, and dump debuging support typically get a ton of (well deserved) buzz and attention when people talk about the debugging improvements with this release.  I’ll be doing blog posts in the future that demonstrate how to take advantage of them as well.  With today’s post, though, I thought I’d start off by covering a few small, but nice, debugger usability improvements that were also included with the VS 2010 release, and which I think you’ll find useful. Breakpoint Labels VS 2010 includes new support for better managing debugger breakpoints.  One particularly useful feature is called “Breakpoint Labels” – it enables much better grouping and filtering of breakpoints within a project or across a solution.  With previous releases of Visual Studio you had to manage each debugger breakpoint as a separate item. Managing each breakpoint separately can be a pain with large projects and for cases when you want to maintain “logical groups” of breakpoints that you turn on/off depending on what you are debugging.  Using the new VS 2010 “breakpoint labeling” feature you can now name these “groups” of breakpoints and manage them as a unit. Grouping Multiple Breakpoints Together using a Label Below is a screen-shot of the breakpoints window within Visual Studio 2010.  This lists all of the breakpoints defined within my solution (which in this case is the ASP.NET MVC 2 code base): The first and last breakpoint in the list above breaks into the debugger when a Controller instance is created or released by the ASP.NET MVC Framework. Using VS 2010, I can now select these two breakpoints, right-click, and then select the new “Edit labels…” menu command to give them a common label/name (making them easier to find and manage): Below is the dialog that appears when I select the “Edit labels” command.  We can use it to create a new string label for our breakpoints or select an existing one we have already defined.  In this case we’ll create a new label called “Lifetime Management” to describe what these two breakpoints cover: When we press the OK button our two selected breakpoints will be grouped under the newly created “Lifetime Management” label: Filtering/Sorting Breakpoints by Label We can use the “Search” combobox to quickly filter/sort breakpoints by label.  Below we are only showing those breakpoints with the “Lifetime Management” label: Toggling Breakpoints On/Off by Label We can also toggle sets of breakpoints on/off by label group.  We can simply filter by the label group, do a Ctrl-A to select all the breakpoints, and then enable/disable all of them with a single click: Importing/Exporting Breakpoints VS 2010 now supports importing/exporting breakpoints to XML files – which you can then pass off to another developer, attach to a bug report, or simply re-load later.  To export only a subset of breakpoints, you can filter by a particular label and then click the “Export breakpoint” button in the Breakpoints window: Above I’ve filtered my breakpoint list to only export two particular breakpoints (specific to a bug that I’m chasing down).  I can export these breakpoints to an XML file and then attach it to a bug report or email – which will enable another developer to easily setup the debugger in the correct state to investigate it on a separate machine.  Pinned DataTips Visual Studio 2010 also includes some nice new “DataTip pinning” features that enable you to better see and track variable and expression values when in the debugger.  Simply hover over a variable or expression within the debugger to expose its DataTip (which is a tooltip that displays its value)  – and then click the new “pin” button on it to make the DataTip always visible: You can “pin” any number of DataTips you want onto the screen.  In addition to pinning top-level variables, you can also drill into the sub-properties on variables and pin them as well.  Below I’ve “pinned” three variables: “category”, “Request.RawUrl” and “Request.LogonUserIdentity.Name”.  Note that these last two variable are sub-properties of the “Request” object.   Associating Comments with Pinned DataTips Hovering over a pinned DataTip exposes some additional UI within the debugger: Clicking the comment button at the bottom of this UI expands the DataTip - and allows you to optionally add a comment with it: This makes it really easy to attach and track debugging notes: Pinned DataTips are usable across both Debug Sessions and Visual Studio Sessions Pinned DataTips can be used across multiple debugger sessions.  This means that if you stop the debugger, make a code change, and then recompile and start a new debug session - any pinned DataTips will still be there, along with any comments you associate with them.  Pinned DataTips can also be used across multiple Visual Studio sessions.  This means that if you close your project, shutdown Visual Studio, and then later open the project up again – any pinned DataTips will still be there, along with any comments you associate with them. See the Value from Last Debug Session (Great Code Editor Feature) How many times have you ever stopped the debugger only to go back to your code and say: $#@! – what was the value of that variable again??? One of the nice things about pinned DataTips is that they keep track of their “last value from debug session” – and you can look these values up within the VB/C# code editor even when the debugger is no longer running.  DataTips are by default hidden when you are in the code editor and the debugger isn’t running.  On the left-hand margin of the code editor, though, you’ll find a push-pin for each pinned DataTip that you’ve previously setup: Hovering your mouse over a pinned DataTip will cause it to display on the screen.  Below you can see what happens when I hover over the first pin in the editor - it displays our debug session’s last values for the “Request” object DataTip along with the comment we associated with them: This makes it much easier to keep track of state and conditions as you toggle between code editing mode and debugging mode on your projects. Importing/Exporting Pinned DataTips As I mentioned earlier in this post, pinned DataTips are by default saved across Visual Studio sessions (you don’t need to do anything to enable this). VS 2010 also now supports importing/exporting pinned DataTips to XML files – which you can then pass off to other developers, attach to a bug report, or simply re-load later. Combined with the new support for importing/exporting breakpoints, this makes it much easier for multiple developers to share debugger configurations and collaborate across debug sessions. Summary Visual Studio 2010 includes a bunch of great new debugger features – both big and small.  Today’s post shared some of the nice debugger usability improvements. All of the features above are supported with the Visual Studio 2010 Professional edition (the Pinned DataTip features are also supported in the free Visual Studio 2010 Express Editions)  I’ll be covering some of the “big big” new debugging features like Intellitrace, parallel/multithreaded debugging, and dump file analysis in future blog posts.  Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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  • jBullet Collision/Physics not working correctly

    - by Kenneth Bray
    Below is the code for one of my objects in the game I am creating (yes although this is a cube, I am not making anything remotely like MineCraft), and my issue is I while the cube will display and is does follow the physics if the cube falls, it does not interact with any other objects in the game. If I was to have multiple cubes in screen at once they all just sit there, or shoot off in all directions never stopping. Anyway, I am new to jBullet, and any help would be appreciated. package Object; import static org.lwjgl.opengl.GL11.GL_QUADS; import static org.lwjgl.opengl.GL11.glBegin; import static org.lwjgl.opengl.GL11.glColor3f; import static org.lwjgl.opengl.GL11.glEnd; import static org.lwjgl.opengl.GL11.glPopMatrix; import static org.lwjgl.opengl.GL11.glPushMatrix; import static org.lwjgl.opengl.GL11.glVertex3f; import javax.vecmath.Matrix4f; import javax.vecmath.Quat4f; import javax.vecmath.Vector3f; import com.bulletphysics.collision.shapes.BoxShape; import com.bulletphysics.collision.shapes.CollisionShape; import com.bulletphysics.dynamics.RigidBody; import com.bulletphysics.dynamics.RigidBodyConstructionInfo; import com.bulletphysics.linearmath.DefaultMotionState; import com.bulletphysics.linearmath.Transform; public class Cube { // Cube size/shape variables private float size; boolean cubeCollidable; boolean cubeDestroyable; // Position variables - currently this defines the center of the cube private float posX; private float posY; private float posZ; // Rotation variables - should be between 0 and 359, might consider letting rotation go higher though I can't think of a purpose currently private float rotX; private float rotY; private float rotZ; //collision shape is a box shape CollisionShape fallShape; // setup the motion state for the ball DefaultMotionState fallMotionState; Vector3f fallInertia = new Vector3f(0, 1, 0); RigidBodyConstructionInfo fallRigidBodyCI; public RigidBody fallRigidBody; int mass = 1; // Constructor public Cube(float pX, float pY, float pZ, float pSize) { posX = pX; posY = pY; posZ = pZ; size = pSize; rotX = 0; rotY = 0; rotZ = 0; // define the physics based on the values passed in fallShape = new BoxShape(new Vector3f(size, size, size)); fallMotionState = new DefaultMotionState(new Transform(new Matrix4f(new Quat4f(0, 0, 0, 1), new Vector3f(0, 50, 0), 1f))); fallRigidBodyCI = new RigidBodyConstructionInfo(mass, fallMotionState, fallShape, fallInertia); fallRigidBody = new RigidBody(fallRigidBodyCI); } public void Update() { Transform trans = new Transform(); fallRigidBody.getMotionState().getWorldTransform(trans); posY = trans.origin.x; posX = trans.origin.y; posZ = trans.origin.z; } public void Draw() { fallShape.calculateLocalInertia(mass, fallInertia); // center point posX, posY, posZ float radius = size / 2; //top glPushMatrix(); glBegin(GL_QUADS); { glColor3f(1.0f,0.0f,0.0f); // red glVertex3f(posX + radius, posY + radius, posZ - radius); glVertex3f(posX - radius, posY + radius, posZ - radius); glVertex3f(posX - radius, posY + radius, posZ + radius); glVertex3f(posX + radius, posY + radius, posZ + radius); } glEnd(); glPopMatrix(); //bottom glPushMatrix(); glBegin(GL_QUADS); { glColor3f(1.0f,1.0f,0.0f); // ?? color glVertex3f(posX + radius, posY - radius, posZ + radius); glVertex3f(posX - radius, posY - radius, posZ + radius); glVertex3f(posX - radius, posY - radius, posZ - radius); glVertex3f(posX + radius, posY - radius, posZ - radius); } glEnd(); glPopMatrix(); //right side glPushMatrix(); glBegin(GL_QUADS); { glColor3f(1.0f,0.0f,1.0f); // ?? color glVertex3f(posX + radius, posY + radius, posZ + radius); glVertex3f(posX + radius, posY - radius, posZ + radius); glVertex3f(posX + radius, posY - radius, posZ - radius); glVertex3f(posX + radius, posY + radius, posZ - radius); } glEnd(); glPopMatrix(); //left side glPushMatrix(); glBegin(GL_QUADS); { glColor3f(0.0f,1.0f,1.0f); // ?? color glVertex3f(posX - radius, posY + radius, posZ - radius); glVertex3f(posX - radius, posY - radius, posZ - radius); glVertex3f(posX - radius, posY - radius, posZ + radius); glVertex3f(posX - radius, posY + radius, posZ + radius); } glEnd(); glPopMatrix(); //front side glPushMatrix(); glBegin(GL_QUADS); { glColor3f(0.0f,0.0f,1.0f); //blue glVertex3f(posX + radius, posY + radius, posZ + radius); glVertex3f(posX - radius, posY + radius, posZ + radius); glVertex3f(posX - radius, posY - radius, posZ + radius); glVertex3f(posX + radius, posY - radius, posZ + radius); } glEnd(); glPopMatrix(); //back side glPushMatrix(); glBegin(GL_QUADS); { glColor3f(0.0f,1.0f,0.0f); // green glVertex3f(posX + radius, posY - radius, posZ - radius); glVertex3f(posX - radius, posY - radius, posZ - radius); glVertex3f(posX - radius, posY + radius, posZ - radius); glVertex3f(posX + radius, posY + radius, posZ - radius); } glEnd(); glPopMatrix(); } }

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  • Mathematica Programming Language&ndash;An Introduction

    - by JoshReuben
    The Mathematica http://www.wolfram.com/mathematica/ programming model consists of a kernel computation engine (or grid of such engines) and a front-end of notebook instances that communicate with the kernel throughout a session. The programming model of Mathematica is incredibly rich & powerful – besides numeric calculations, it supports symbols (eg Pi, I, E) and control flow logic.   obviously I could use this as a simple calculator: 5 * 10 --> 50 but this language is much more than that!   for example, I could use control flow logic & setup a simple infinite loop: x=1; While [x>0, x=x,x+1] Different brackets have different purposes: square brackets for function arguments:  Cos[x] round brackets for grouping: (1+2)*3 curly brackets for lists: {1,2,3,4} The power of Mathematica (as opposed to say Matlab) is that it gives exact symbolic answers instead of a rounded numeric approximation (unless you request it):   Mathematica lets you define scoped variables (symbols): a=1; b=2; c=a+b --> 5 these variables can contain symbolic values – you can think of these as partially computed functions:   use Clear[x] or Remove[x] to zero or dereference a variable.   To compute a numerical approximation to n significant digits (default n=6), use N[x,n] or the //N prefix: Pi //N -->3.14159 N[Pi,50] --> 3.1415926535897932384626433832795028841971693993751 The kernel uses % to reference the lastcalculation result, %% the 2nd last, %%% the 3rd last etc –> clearer statements: eg instead of: Sqrt[Pi+Sqrt[Sqrt[Pi+Sqrt[Pi]]] do: Sqrt[Pi]; Sqrt[Pi+%]; Sqrt[Pi+%] The help system supports wildcards, so I can search for functions like so: ?Inv* Mathematica supports some very powerful programming constructs and a rich function library that allow you to do things that you would have to write allot of code for in a language like C++.   the Factor function – factorization: Factor[x^3 – 6*x^2 +11x – 6] --> (-3+x) (-2+x) (-1+x)   the Solve function – find the roots of an equation: Solve[x^3 – 2x + 1 == 0] -->   the Expand function – express (1+x)^10 in polynomial form: Expand[(1+x)^10] --> 1+10x+45x^2+120x^3+210x^4+252x^5+210x^6+120x^7+45x^8+10x^9+x^10 the Prime function – what is the 1000th prime? Prime[1000] -->7919 Mathematica also has some powerful graphics capabilities:   the Plot function – plot the graph of y=Sin x in a single period: Plot[Sin[x], {x,0,2*Pi}] you can also plot 3D surfaces of functions using Plot3D function

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  • Segfault when iterating over a map<string, string> and drawing its contents using SDL_TTF

    - by Michael Stahre
    I'm not entirely sure this question belongs on gamedev.stackexchange, but I'm technically working on a game and working with SDL, so it might not be entirely offtopic. I've written a class called DebugText. The point of the class is to have a nice way of printing values of variables to the game screen. The idea is to call SetDebugText() with the variables in question every time they change or, as is currently the case, every time the game's Update() is called. The issue is that when iterating over the map that contains my variables and their latest updated values, I get segfaults. See the comments in DrawDebugText() below, it specifies where the error happens. I've tried splitting the calls to it-first and it-second into separate lines and found that the problem doesn't always happen when calling it-first. It alters between it-first and it-second. I can't find a pattern. It doesn't fail on every call to DrawDebugText() either. It might fail on the third time DrawDebugText() is called, or it might fail on the fourth. Class header: #ifndef CLIENT_DEBUGTEXT_H #define CLIENT_DEBUGTEXT_H #include <Map> #include <Math.h> #include <sstream> #include <SDL.h> #include <SDL_ttf.h> #include "vector2.h" using std::string; using std::stringstream; using std::map; using std::pair; using game::Vector2; namespace game { class DebugText { private: TTF_Font* debug_text_font; map<string, string>* debug_text_list; public: void SetDebugText(string var, bool value); void SetDebugText(string var, float value); void SetDebugText(string var, int value); void SetDebugText(string var, Vector2 value); void SetDebugText(string var, string value); int DrawDebugText(SDL_Surface*, SDL_Rect*); void InitDebugText(); void Clear(); }; } #endif Class source file: #include "debugtext.h" namespace game { // Copypasta function for handling the toString conversion template <class T> inline string to_string (const T& t) { stringstream ss (stringstream::in | stringstream::out); ss << t; return ss.str(); } // Initializes SDL_TTF and sets its font void DebugText::InitDebugText() { if(TTF_WasInit()) TTF_Quit(); TTF_Init(); debug_text_font = TTF_OpenFont("LiberationSans-Regular.ttf", 16); TTF_SetFontStyle(debug_text_font, TTF_STYLE_NORMAL); } // Iterates over the current debug_text_list and draws every element on the screen. // After drawing with SDL you need to get a rect specifying the area on the screen that was changed and tell SDL that this part of the screen needs to be updated. this is done in the game's Draw() function // This function sets rects_to_update to the new list of rects provided by all of the surfaces and returns the number of rects in the list. These two parameters are used in Draw() when calling on SDL_UpdateRects(), which takes an SDL_Rect* and a list length int DebugText::DrawDebugText(SDL_Surface* screen, SDL_Rect* rects_to_update) { if(debug_text_list == NULL) return 0; if(!TTF_WasInit()) InitDebugText(); rects_to_update = NULL; // Specifying the font color SDL_Color font_color = {0xff, 0x00, 0x00, 0x00}; // r, g, b, unused int row_count = 0; string line; // The iterator variable map<string, string>::iterator it; // Gets the iterator and iterates over it for(it = debug_text_list->begin(); it != debug_text_list->end(); it++) { // Takes the first value (the name of the variable) and the second value (the value of the parameter in string form) //---------THIS LINE GIVES ME SEGFAULTS----- line = it->first + ": " + it->second; //------------------------------------------ // Creates a surface with the text on it that in turn can be rendered to the screen itself later SDL_Surface* debug_surface = TTF_RenderText_Solid(debug_text_font, line.c_str(), font_color); if(debug_surface == NULL) { // A standard check for errors fprintf(stderr, "Error: %s", TTF_GetError()); return NULL; } else { // If SDL_TTF did its job right, then we now set a destination rect row_count++; SDL_Rect dstrect = {5, 5, 0, 0}; // x, y, w, h dstrect.x = 20; dstrect.y = 20*row_count; // Draws the surface with the text on it to the screen int res = SDL_BlitSurface(debug_surface,NULL,screen,&dstrect); if(res != 0) { //Just an error check fprintf(stderr, "Error: %s", SDL_GetError()); return NULL; } // Creates a new rect to specify the area that needs to be updated with SDL_Rect* new_rect_to_update = (SDL_Rect*) malloc(sizeof(SDL_Rect)); new_rect_to_update->h = debug_surface->h; new_rect_to_update->w = debug_surface->w; new_rect_to_update->x = dstrect.x; new_rect_to_update->y = dstrect.y; // Just freeing the surface since it isn't necessary anymore SDL_FreeSurface(debug_surface); // Creates a new list of rects with room for the new rect SDL_Rect* newtemp = (SDL_Rect*) malloc(row_count*sizeof(SDL_Rect)); // Copies the data from the old list of rects to the new one memcpy(newtemp, rects_to_update, (row_count-1)*sizeof(SDL_Rect)); // Adds the new rect to the new list newtemp[row_count-1] = *new_rect_to_update; // Frees the memory used by the old list free(rects_to_update); // And finally redirects the pointer to the old list to the new list rects_to_update = newtemp; newtemp = NULL; } } // When the entire map has been iterated over, return the number of lines that were drawn, ie. the number of rects in the returned rect list return row_count; } // The SetDebugText used by all the SetDebugText overloads // Takes two strings, inserts them into the map as a pair void DebugText::SetDebugText(string var, string value) { if (debug_text_list == NULL) { debug_text_list = new map<string, string>(); } debug_text_list->erase(var); debug_text_list->insert(pair<string, string>(var, value)); } // Writes the bool to a string and calls SetDebugText(string, string) void DebugText::SetDebugText(string var, bool value) { string result; if (value) result = "True"; else result = "False"; SetDebugText(var, result); } // Does the same thing, but uses to_string() to convert the float void DebugText::SetDebugText(string var, float value) { SetDebugText(var, to_string(value)); } // Same as above, but int void DebugText::SetDebugText(string var, int value) { SetDebugText(var, to_string(value)); } // Vector2 is a struct of my own making. It contains the two float vars x and y void DebugText::SetDebugText(string var, Vector2 value) { SetDebugText(var + ".x", to_string(value.x)); SetDebugText(var + ".y", to_string(value.y)); } // Empties the list. I don't actually use this in my code. Shame on me for writing something I don't use. void DebugText::Clear() { if(debug_text_list != NULL) debug_text_list->clear(); } }

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  • Loading class instance from XML with Texture2D

    - by Thegluestickman
    I'm having trouble with XML and XNA. I want to be able to load weapon settings through XML to make my weapons easier to make and to have less code in the actual project file. So I started out making a basic XML document, something to just assign variables with. But no matter what I changed it gave me a new error every time. The code below gives me a "XML element 'Tag' not found", I added and it started to say the variables weren't found. What I wanted to do in the XML file as well, was load a texture for the file too. So I created a static class to hold my texture values, then in the Texture tag of my XML document I would set it to that instance too. I think that's were the problems are occuring because that's where the "XML element 'Tag' not found" error is pointing me too. My XML document: <XnaContent> <Asset Type="ConversationEngine.Weapon"> <weaponStrength>0</weaponStrength> <damageModifiers>0</damageModifiers> <speed>0</speed> <magicDefense>0</magicDefense> <description>0</description> <identifier>0</identifier> <weaponTexture>LoadWeaponTextures.ironSword</weaponTexture> </Asset> </XnaContent> My Class to load the weapon XML: public class Weapon { public int weaponStrength; public int damageModifiers; public int speed; public int magicDefense; public string description; public string identifier; public Texture2D weaponTexture; } public static class LoadWeaponXML { static Weapon Weapons; public static Weapon WeaponLoad(ContentManager content, int id) { Weapons = content.Load<Weapon>(@"Weapons/" + id); return Weapons; } } public static class LoadWeaponTextures { public static Texture2D ironSword; public static void TextureLoad(ContentManager content) { ironSword = content.Load<Texture2D>("Sword"); } } I'm not entirely sure if you can load textures through XML, but any help would be greatly appreciated.

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