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• Where Are Multiple JUnit Test Methods Typically Placed in Code?

  - by Thunderforge

  I've just read the Vogella JUnit tutorial and found it very helpful in understanding how to use JUnit. However, I'm a bit confused about what the convention is for placing multiple test methods in code. The tutorial only places one test method in a class, then describes how you can use a test suite to group multiple test classes together. Does this mean that it's common practice for each test class to only have one test method and then test suites are used to chain them together? Or was that just unintended and instead common practice is to put multiple test methods in a class?

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• Draw "vision cone" / targetting element onto game world

  - by gkimsey

  I'm wanting to indicate various things using a "pie slice" sort of shape as below. Similar to vision cones in stealth game minimaps, or targetting indicators in RTS type games for frontal area attacks. Something generic enough to be used for both would be ideal. I need to be able to procedurally (and efficiently) change things like the slice width and length, color, transparency, position in the world, etc. For my particular situation, there's no concern with elevation, funky terrain, or really any third axis at all as far as this element is concerned. I have two first inclinations on how to accomplish this: 1) Manually generate the vertices for a main triangle, (possibly two, superimposed to get the border effect), a handful more to approximate the arc at the end, and roll it into a mesh. 2) Use some sort of 2D drawing library to create a circle and mask it off at the right angles, render to texture, and use that. For reference, I have some experience with Ogre3D, but I'm not attached to it as this is a mostly academic pursuit at the moment. Other technologies that might be better at accomplishing this are more than welcome. Finally, I'm kind of curious about how to do a "flashlight" or similar 3D effect that could produce the same result, but on all surfaces in the lit area.

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• Architecting persistence (and other internal systems). Interfaces, composition, pure inheritance or centralization?

  - by Vandell

  Suppose that you need to implement persistence, I think that you're generally limited to four options (correct me if I'm wrong, please) Each persistant class: Should implement an interface (IPersistent) Contains a 'persist-me' object that is a specialized object (or class) that's made only to be used the class that contains it. Inherit from Persistent (a base class) Or you can create a gigantic class (or package) called Database and make your persistence logic there. What are the advantages and problems that can come from each of one? In a small (5kloc) and algorithmically (or organisationally) simple app what is probably the best option?

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• Grid collision - finding the location of an entity in each box

  - by Gregg1989

  I am trying to implement grid-based collision in a 2d game with moving circles. The canvas is 400x400 pixels. Below you can see the code for my Grid class. What I want it to do is check inside which box the entities are located and then run a collision check if there are 2 or more entities in the same box. Right now I do not know how to find the position of an entity in a specific box. I know there are many tutorials online, but I haven't been able to find an answer to my question, because they are either written in C/C++ or use the 2d array approach. Code snippets and other help is greatly appreciated. Thanks. public class Grid { ArrayList<ArrayList<Entity>> boxes = new ArrayList<>(); double boxSize = 40; double boxesAmount = 10; ... ... public void checkBoxLocation(ArrayList<Entity> entities) { for (int i = 0; i < entities.size(); i++) { // Get top left coordinates of each entity double entityLeft = entities.get(i).getLayoutX() - entities.get(i).getRadius(); double entityTop = entities.get(i).getLayoutY() + entities.get(i).getRadius(); // Divide coordinate by box size to find the approximate location of the entity for (int j = 0; j < boxesAmount; j++) { //Select each box if ((entityLeft / boxSize <= j + 0.7) && (entityLeft / boxSize >= j)) { if ((entityTop / boxSize <= j + 0.7) && (entityTop / boxSize >= j)) { holdingBoxes.get(j).add(entities.get(i)); System.out.println("Entity " + entities.get(i) + " added to box " + j); } } } } } }

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• Clarify the Single Responsibility Principle.

  - by dsimcha

  The Single Responsibility Principle states that a class should do one and only one thing. Some cases are pretty clear cut. Others, though, are difficult because what looks like "one thing" when viewed at a given level of abstraction may be multiple things when viewed at a lower level. I also fear that if the Single Responsibility Principle is honored at the lower levels, excessively decoupled, verbose ravioli code, where more lines are spent creating tiny classes for everything and plumbing information around than actually solving the problem at hand, can result. How would you describe what "one thing" means? What are some concrete signs that a class really does more than "one thing"?

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• Should static parameters in an API be part of each method?

  - by jschoen

  I am currently creating a library that is a wrapper for an online API. The obvious end goal is to make it as easy for others to use as possible. As such I am trying to determine the best approach when it comes to common parameters for the API. In my current situation there are 3 (consumer key, consumer secret, and and authorization token). They are essentially needed in every API call. My question is should I make these 3 parameters required for each method or is there a better way. I see my current options as being: Place the parameters in each method call public ApiObject callMethod(String consumerKey, String consumerSecret, String token, ...) This one seems reasonable, but seems awfully repetitive to me. Create a singleton class that the user must initialize before calling any api methods. This seems wrong, and would essentially limit them to accessing one account at a time via the API (which may be reasonable, I dunno). Make them place them in a properties file in their project. That way I can load the properties that way and store them. This seems similar to the singleton to me, but they would not have to explicitly call something to initialize these values. Is there another option I am not seeing, or a more common practice in this situation that I should be following?

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• Is there any complications or side effects for changing final field access/visibility modifier from private to protected?

  - by Software Engeneering Learner

  I have a private final field in one class and then I want to address that field in a subclass. I want to change field access/visibility modifier from private to protected, so I don't have to call getField() method from subclass and I can instead address that field directly (which is more clear and cohessive). Will there be any side effects or complications if I change private to protected for a final field? UPDATE: from logical point of view, it's obvious that descendant should be able to directly access all predecessor fields, right? But there are certain constraints that are imposed on private final fields by JVM, like 100% initialization guarantee after construction phase(useful for concurrency) and so on. So I would like to know, by changing from private to protected, won't that or any other constraints be compromised?

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• Where to get PNG icons/graphics for game development for kids? [closed]

  - by at.

  Possible Duplicate: Where can I find free sprites and images? I'm teaching kids to program using Ruby and the gaming framework Gosu/Chingu. Kids love it, including the part where they have to look for the icons/graphics for their game objects. I direct them to iconarchive.com, but the selection is sometimes very limited, the graphics aren't always with transparent backgrounds and sometimes the art requires payment. I don't mind paying for an educational license of some sort, but I want the kids to easily select graphics they can use in their games. Is there another resource better suited for this purpose? I don't have a good solution for this, but would also love a site they can get cool background images for their games.

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• Matrix loading problems with jbullet and lwjgl

  - by Quintin

  The following code does not load the matrix correctly from jbullet. //box is a RigidBody Transform trans = new Transform(); trans = box.getMotionState().getWorldTransform(trans); float[] matrix = new float[16]; trans.getOpenGLMatrix(matrix); // pass that matrix to OpenGL and render the cube FloatBuffer buffer = ByteBuffer.allocateDirect(4*16).asFloatBuffer().put(matrix); buffer.rewind(); glPushMatrix(); glMultMatrix(buffer); glBegin(GL_POINTS); glVertex3f(0,0,0); glEnd(); glPopMatrix(); the jbullet is configured as so: CollisionConfiguration = new DefaultCollisionConfiguration(); dispatcher = new CollisionDispatcher(collisionConfiguration); Vector3f worldAabbMin = new Vector3f(-10000,-10000,-10000); Vector3f worldAabbMax = new Vector3f(10000,10000,10000); AxisSweep3 overlappingPairCache = new AxisSweep3(worldAabbMin, worldAabbMax); SequentialImpulseConstraintSolver solver = new SequentialImpulseConstraintSolver(); dynamicWorld = new DiscreteDynamicsWorld(dispatcher, overlappingPairCache, solver, collisionConfiguration); dynamicWorld.setGravity(new Vector3f(0,-10,0)); dynamicWorld.getDispatchInfo().allowedCcdPenetration = 0f; CollisionShape groundShape = new BoxShape(new Vector3f(1000.f, 50.f, 1000.f)); Transform groundTransform = new Transform(); groundTransform.setIdentity(); groundTransform.origin.set(new Vector3f(0.f, -60.f, 0.f)); float mass = 0f; Vector3f localInertia = new Vector3f(0, 0, 0); DefaultMotionState myMotionState = new DefaultMotionState(groundTransform); RigidBodyConstructionInfo rbInfo = new RigidBodyConstructionInfo(mass, myMotionState, groundShape, localInertia); RigidBody body = new RigidBody(rbInfo); dynamicWorld.addRigidBody(body); dynamicWorld.clearForces(); Nothing is rendered on the screen. What am I doing wrong?

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• Mobile Compatibility: traditional website look vs native application ?

  - by Siddiqui

  I have a question related to mobile compatible websites, I have seen two type of websites One in which they adopt traditional website look and adjust website according to mobile screen, if they have lot of information which can not be adjust according to screen then they expand the height of page, so that user can scroll the page to see more information... In the second approach they used native application look means use navigation-bar, tab-bar, tool-bar, scroll-view just like in native applications. Height and width of page adjust according to screen size, if they have more information then they use scroll-view etc... My question is: which approach is better then other, in which approach you feel more comfortable to use website.

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• Best Practice: What can be the hashCode() method implementation if custom field used in equals() method are null?

  - by goodspeed

  What is the best practice to return a value for hashCode() method if custom field used in equals are null ? I have a situation, where equals() override is implemented using custom fields. Usually it it is better to override hashCode() also using that custom fields used in equals(). But if all the custom fields used in equals() are null, then what would be the best implementation for hashCode()? Example: class Person { private String firstName; private String lastName; public String getFirstName() { return firstName; } public String getLastName() { return lastName; } @Override public boolean equals(Object object) { boolean result = false; if (object == null || object.getClass() != getClass()) { result = false; } else { Person person = (Person) object; if (this.firstName == person.getFirstName() && this.lastName == tiger.getLastName()) { result = true; } } return result; } @Override public int hashCode() { int hash = 3; if(this.firstName == null || this.lastName == null) { // <b>What is the best practice here, </b> // <b>is return super.hashCode() better ?</b> } hash = 7 * hash + this.firstName.hashCode(); hash = 7 * hash + this.lastName.hashCode(); return hash; } } is it required to check for null in hashCode() ? If yes, what should be returned if custom values are null ?

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• JS / HTML 5 Compatablity issue on iOS 6

  - by Dhaval

  I'm using HTML 5 to play video and there are some content before the video so I'm using flexroll to scroll that whole window. I'm checking it on iPad, now problem is that in iOS 5 its working fine but when I update to iOS 6 then screen is not scrolling only video is scroll up and down, content is as it is in the position. I can't understand what is the exact problem. Is that js compatibility issue or HTML 5 video compatibility issue. Can anyone please help me to figure out, your help will really be appreciated.

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• Handling commands or events that wait for an action to be completed afterwards

  - by virulent

  Say you have two events: Action1 and Action2. When you receive Action1, you want to store some arbitrary data to be used the next time Action2 rolls around. Optimally, Action1 is normally a command however it can also be other events. The idea is still the same. The current way I am implementing this is by storing state and then simply checking when Action2 is called if that specific state is there. This is obviously a bit messy and leads to a lot of redundant code. Here is an example of how I am doing that, in pseudocode form (and broken down quite a bit, obviously): void onAction1(event) { Player = event.getPlayer() Player.addState("my_action_to_do") } void onAction2(event) { Player = event.getPlayer() if not Player.hasState("my_action_to_do") { return } // Do something } When doing this for a lot of other actions it gets somewhat ugly and I wanted to know if there is something I can do to improve upon it. I was thinking of something like this, which wouldn't require passing data around, but is this also not the right direction? void onAction1(event) { Player = event.getPlayer() Player.onAction2(new Runnable() { public void run() { // Do something } }) } If one wanted to take it even further, could you not simply do this? void onPlayerEnter(event) { // When they join the server Player = event.getPlayer() Player.onAction1(new Runnable() { public void run() { // Now wait for action 2 Player.onAction2(new Runnable() { // Do something }) } }, true) // TRUE would be to repeat the event, // not remove it after it is called. } Any input would be wonderful.

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• Bluetooth push application

  - by Paul Kassey

  I am considering the technical viability of software that I want to write. Is there a way that I can push data to a phone (iPhone or Andriod) via Bluetooth without pairing with it? I want to be able to walk into a room and have a computer push data to my phone when I get a certain distance from it, or push data to any phone automatically when it comes within a certain distance to a Bluetooth-ready device?

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• Is it okay to introduce LESS to not so savvy UI Designers?

  - by Jason Nathan

  I just got a job as lead developer and I thought it would be best to seek the expertise of my peers (that's you) before proceeding! I had the opportunity to review my designers and they are mostly photoshop pros with dreamweaver as their main HTML/CSS editor. A more visual experience. I, on the other hand, have had much experience hand-writing all my code. From HTML markup to CSS. From my understanding, my designers have basic CSS knowledge and I am considering a simple 101 style set of tutorials for them to get a better grasp of markup before I moved into more advanced topics like accessibility and microformat markup. We need to get started up quickly. Do you think it's okay to dive into LESS from the get-go?

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• What would be the market life of a JVM based software framework?

  - by Nav

  I saw how Struts 1 lasted from 2000 to 2013. I hear that people are moving from Struts 2 to Spring. But for a project that may need to be maintained for a decade or two, would it be advisable to opt for a framework or directly code with servlets and jquery? Can a system architecture really be designed keeping in mind a particular framework? What really is the market life of a framework? Do the creators of the framework create it with the assumption that it would become obsolete in a decade?

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• Access Token Verification

  - by DecafCoder

  I have spent quite a few days reading up on Oauth and token based security measures for REST API's and I am currently looking at implementing an Oauth based authentication approach almost exactly like the one described in this post (OAuth alternative for a 2 party system). From what I understand, the token is to be verified upon each request to the resource server. This means the resource server would need to retrieve the token from a datastore to verify the clients token. Given this would have to happen upon every request I am concerned about the speed implications of hitting a datastore like MySQL or NoSQL upon every request just to verify the token. Is this the standard way to verify tokens by having them stored in a RDBMS or NoSQL database and retrieved upon each request? Or is it a suitable solution to have them cached (baring in mind that we are talking millions of users)?

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• Mahout - Clustering - "naming" the cluster elements

  - by Mark Bramnik

  I'm doing some research and I'm playing with Apache Mahout 0.6 My purpose is to build a system which will name different categories of documents based on user input. The documents are not known in advance and I don't know also which categories do I have while collecting these documents. But I do know, that all the documents in the model should belong to one of the predefined categories. For example: Lets say I've collected a N documents, that belong to 3 different groups : Politics Madonna (pop-star) Science fiction I don't know what document belongs to what category, but I know that each one of my N documents belongs to one of those categories (e.g. there are no documents about, say basketball among these N docs) So, I came up with the following idea: Apply mahout clustering (for example k-mean with k=3 on these documents) This should divide the N documents to 3 groups. This should be kind of my model to learn with. I still don't know which document really belongs to which group, but at least the documents are clustered now by group Ask the user to find any document in the web that should be about 'Madonna' (I can't show to the user none of my N documents, its a restriction). Then I want to measure 'similarity' of this document and each one of 3 groups. I expect to see that the measurement for similarity between user_doc and documents in Madonna group in the model will be higher than the similarity between the user_doc and documents about politics. I've managed to produce the cluster of documents using 'Mahout in Action' book. But I don't understand how should I use Mahout to measure similarity between the 'ready' cluster group of document and one given document. I thought about rerunning the cluster with k=3 for N+1 documents with the same centroids (in terms of k-mean clustering) and see whether where the new document falls, but maybe there is any other way to do that? Is it possible to do with Mahout or my idea is conceptually wrong? (example in terms of Mahout API would be really good) Thanks a lot and sorry for a long question (couldn't describe it better) Any help is highly appreciated P.S. This is not a home-work project :)

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• Search multiple tables

  - by gilden

  I have developed a web application that is used mainly for archiving all sorts of textual material (documents, references to articles, books, magazines etc.). There can be any given number of archive tables in my system, each with its own schema. The schema can be changed by a moderator through the application (imagine something similar to a really dumbed down version of phpMyAdmin). Users can search for anything from all of the tables. By using FULLTEXT indexes together with substring searching (fields which do not support FULLTEXT indexing) the script inserts the results of a search to a single table and by ordering these results by the similarity measure I can fairly easily return the paginated results. However, this approach has a few problems: substring searching can only count exact results the 50% rule applies to all tables separately and thus, mysql may not return important matches or too naively discards common words. is quite expensive in terms of query numbers and execution time (not an issue right now as there's not a lot of data yet in the tables). normalized data is not even searched for (I have different tables for categories, languages and file attatchments). My planned solution Create a single table having columns similar to id, table_id, row_id, data Every time a new row is created/modified/deleted in any of the data tables this central table also gets updated with the data column containing a concatenation of all the fields in a row. I could then create a single index for Sphinx and use it for doing searches instead. Are there any more efficient solutions or best practises how to approach this? Thanks.

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• How to implement a multi-part snake with smooth movement? [closed]

  - by Jamie

  Sorry that i couldnt answer on my previous post but it got closed. I couldnt answer because i had to prepair for my finals. As there were problems with understanding of what im trying to achieve, im going to describe a little bit more in depth. Im creating a game in which you steer a snake. I assume everybody knows how that works. But in my case the snake isnt just propagating in an array element by element. Imagine a 2Dgrid on which the snake moves. Its 10x10 tiles. Lets say one tile is 4x4 meters. The snakes head spawns in the middle of the (3,2) tile (beginning with (0,0)), so its position is (4*3+2,4*2+2)(the 2's are so that the snake is in the middle of the 4x4 tile). And heres where the fun begins. when the snake moves, it doesnt jump to next tile. Instead it moves a fraction of the way there. So lets say the snake is heading to tile (4,2). After it moved once, its position is (4*3+2+0.1,4*2+2), where 0.1 is the fraction of the way it moved. This is done to achieve smooth movement. So now im adding the rest of the body. The rest is supposed to move along the exact same path as the head did. I implemented it so that each part of the body has its own position and direction. Then i apply this algorithm: 1.Move each part in its direction. 2.If a part is in the middle of the tile(which implies all of them are), change each parts direction to the direction of the part proceeding it. As i said before i could make this work, but i cant stop thinking that im overlooking a much easier and cleaner solution. So this is my question. Is there any easier/better/faster way to do this?

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• Using Single Image for Map in 2D Platformer

  - by Jon

  I'm fairly new to game development, and have been messing around with Slick2D. Currently, my map consists of objects that are represented as rectangles. If I wanted to use am image simlar to: How would I be able to use this image to make a level? That question is a bit vague, but like I said, I'm new to game development and am not familiar with terminology or procedures. But going along with this question, how would I also use non-rectangular objects/platforms? Thanks

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• Help with Meshes, and Shading

  - by Brian Diehr

  In a game I'm making in LibGdx, I wish to incorporate a ripple effect. I'm confused as to how I get access to the individual pixels on the screen, or any way to influence them (apart from what I can do with sprite batch). I have my suspicions that I have to do it through openGL, and it has something to do with apply a mesh? This brings me to my question, what exactly is a mesh? I've been working on my game for about half a year, and am doing great with the other aspects of the game, but I find this more advance stuff isn't as well documented. Thanks!

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• Lwjgl camera causing movement to be mirrored

  - by pangaea

  I'm having a problem in that everything is rendered and the movement is fine. However, everything seems to be mirrored. In the sense that the TriangleMob should move towards me, but it doesn't instead it mirrors my action. I move forward the TriangleMob moves backwards. I move left, it moves right. I move backwards, it moves forward. The code works if I do this glPushMatrix(); glTranslatef(-position.x, -position.y, -position.z); glCallList(objectDisplayList); glPopMatrix(); However, I'm scared this will cause a problem later on. I suppose the code works. However, shouldn't the call be glPushMatrix(); glTranslatef(position.x, position.y, position.z); glCallList(objectDisplayList); glPopMatrix(); I think the problem could be caused by how I'm doing the camera, which is this glLoadIdentity(); glRotatef(player.getRotation().x, 1.0f, 0.0f, 0.0f); glRotatef(player.getRotation().y, 0.0f, 1.0f, 0.0f); glRotatef(player.getRotation().z, 0.0f, 0.0f, 1.0f); glTranslatef(player.getPosition().x, player.getPosition().y, player.getPosition().z);

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• Repository query conditions, dependencies and DRY

  - by vFragosop

  To keep it simple, let's suppose an application which has Accounts and Users. Each account may have any number of users. There's also 3 consumers of UserRepository: An admin interface which may list all users Public front-end which may list all users An account authenticated API which should only list it's own users Assuming UserRepository is something like this: class UsersRepository extends DatabaseAbstraction { private function query() { return $this->database()->select('users.*'); } public function getAll() { return $this->query()->exec(); } // IMPORTANT: // Tons of other methods for searching, filtering, // joining of other tables, ordering and such... } Keeping in mind the comment above, and the necessity to abstract user querying conditions, How should I handle querying of users filtering by account_id? I can picture three possible roads: 1. Should I create an AccountUsersRepository? class AccountUsersRepository extends UserRepository { public function __construct(Account $account) { $this->account = $account; } private function query() { return parent::query() ->where('account_id', '=', $this->account->id); } } This has the advantage of reducing the duplication of UsersRepository methods, but doesn't quite fit into anything I've read about DDD so far (I'm rookie by the way) 2. Should I put it as a method on AccountsRepository? class AccountsRepository extends DatabaseAbstraction { public function getAccountUsers(Account $account) { return $this->database() ->select('users.*') ->where('account_id', '=', $account->id) ->exec(); } } This requires the duplication of all UserRepository methods and may need another UserQuery layer, that implements those querying logic on chainable way. 3. Should I query UserRepository from within my account entity? class Account extends Entity { public function getUsers() { return UserRepository::findByAccountId($this->id); } } This feels more like an aggregate root for me, but introduces dependency of UserRepository on Account entity, which may violate a few principles. 4. Or am I missing the point completely? Maybe there's an even better solution? Footnotes: Besides permissions being a Service concern, in my understanding, they shouldn't implement SQL query but leave that to repositories since those may not even be SQL driven.

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• How to calculate production when player is offline

  - by Kaizer

  What is the best way to do for example food growth based on how many food buildings you have? Lets say I have a webbased game where you can build a farm wich generates 60 food units per hour. A player has 1 farm in his possession. What is the best way to keep on producing these units even when the player is offline? Should I do the math when the player get's back online again? If so..how can I do this without having to save his last online time every 5 seconds so I can do some maths with it when he logs back in (datetime.now - lastonlinetime)? Next thing is when the player is online, should I refresh his resource count every 5 seconds or so by going to the database and back? This would seem weird to do for every logged on player. I hope you understand my question. kind regards

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