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  • Growing your VirtualBox Virtual Disk

    - by Fat Bloke
    Don't you just hate it when this happens: Fortunately, if you're running inside VirtualBox, you can resize your virtual disk and magically make your guest have a bigger disk very easily. There are 2 steps to doing this... 1. Resize the virtual disk Use the VBoxManage command line tool to extend the size of the Virtual Disk, specifying the path to the disk and the size in MB: VBoxManage modifyhd <uuid>|<filename> [--type normal|writethrough|immutable|shareable| readonly|multiattach] [--autoreset on|off] [--compact] [--resize <megabytes>|--resizebyte <bytes>]   If you booted up your guest at this point, the extra space is seen as an unformatted area on the disk, like this: So we now need to tell the guest about the extra space available. 2. Extend the guest's partition to use the extra space How you do this step depends on you guest OS type and the tools you have available. Linux guests often include the excellent gparted partition editor, whereas Windows 7 and 8 provide the Computer Management tool which can resize partitions. Unfortunately, my Windows XP vm has no such tool. But I do have a couple of other options: Most Linux installable .isos include the aforementioned gparted tool, so I could simply attach, say, an Ubuntu.iso as a Virtual CD/DVD in my Windows XP vm and boot off that. Then use gparted to extend the Windows XP partition, before finally rebooting. But I took another route and attached my resized virtual disk to a Windows Server 2012 vm I had lying around. Then I used the Computer Management tool in Windows Server 2012 to extend the partition of the Windows XP disk, before shutting down, unplugging the disk and reattaching to my Windows XP vm. (Note that if your vm's use different disk controllers, Windows will check the disks on booting). When I finally boot up my Windows XP guest I see the available disk space and all is well. At least until the next time - FB 

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  • What is a suitable way to correct this program? [closed]

    - by lamwaiman1988
    Possible Duplicate: How to deal with huge changes to a data specification? As described in this question, I need to modified a 4800 line c program to fulfill the new functional specification. However I have no idea of HOW to do it. Background: There is a updated version of a header file which the program depends on. I've speculated the changes and found that at least 30 critical changes are present. With the new header file, the c program cannot even compile. The error is too much that the compile said "too much error" and don't list every one. Unlike normal modification which can be easily test, this has no way to test without overcoming the 30 critical changes. For example, there would be no point to run the modified program with the old header file. On the other hand, with the new header file, the program can't run until I've covered every one of the 30 critical changes scattered in the new header file so that I can't even verify the correctness of each modification until there is no more compilation error. Do you have any idea to deal with this situation?

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  • Animating the offset of the scrollView in a UICollectionView/UITableView causes prematurely disappearing cells

    - by radutzan
    We have a UICollectionView with a custom layout very similar to UITableView (it scrolls vertically). The UICollectionView displays only 3 cells simultaneously, with one of them being the currently active cell: [ 1 ] [*2*] [ 3 ] (The active cell here is #2.) The cells are roughly 280 points high, so only the active cell is fully visible on the screen. The user doesn't directly scroll the view to navigate, instead, she swipes the active cell horizontally to advance to the next cell. We then do some fancy animations and scroll the UICollectionView so the next cell is in the "active" position, thus making it the active one, moving the old one away and bringing up the next cell in the queue: [ 2 ] [*3*] [ 4 ] The problem here is setting the UICollectionView's offset. We currently set it in a UIView animation block (self.collectionView.contentOffset = targetOffset;) along with three other animating properties, which mostly works great, but causes the first cell (the previously active one, in the latter case, #2) to vanish as soon as the animation starts running, even before the delay interval completes. This is definitely not ideal. I've thought of some solutions, but can't figure out the best one: Absurdly enlarge the UICollectionView's frame to fit five cells instead of three, thus forcing it to keep the cells in memory even if they are offscreen. I've tried this and it works, but it sounds like an awfully dirty hack. Take a snapshot of the rendered content of the vanishing cell, put it in a UIImageView, add the UIImageView as a subview of the scrollView just before the cell goes away in the exact same position of the old cell, removing it once the animation ends. Sounds less sucky than the previous option (memory-wise, at least), but still kinda hacky. I also don't know the best way to accomplish this, please point me in the right direction. Switch to UIScrollView's setContentOffset:animated:. We actually used to have this, and it fixed the disappearing cell issue, but running this in parallel with the other UIView animations apparently competes for the attention of the main thread, thus creating a terribly choppy animation on single-core devices (iPhone 3GS/4). It also doesn't allow us to change the duration or easing of the animation, so it feels out of sync with the rest. Still an option if we can find a way to make it work in harmony with the UIView block animations. Switch to UICollectionView's scrollToItemAtIndexPath:atScrollPosition:animated:. Haven't tried this, but it has a big downside: it only takes 3 possible constants (that apply to this case, at least) for the target scroll position: UICollectionViewScrollPositionTop, UICollectionViewScrollPositionCenteredVertically and UICollectionViewScrollPositionBottom. The active cell could vary its height, but it always has to be 35 points from the top of the window, and these options don't provide enough control to accomplish the design. It could also potentially be just as problematic as 3.1. Still an option because there might be a way to go around the scroll position thing that I don't know of, and it might not have the same issue with the main thread, which seems unlikely. Any help will be greatly appreciated. Please ask if you need clarification. Thanks a lot!

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  • How to fix notifyDataSetChanged/ListView problems in dynamic Adapter wrapper Android

    - by ipaterson
    Summary: Trying to dynamically add heading rows to a ListView via a custom adapter wrapper. ListView is having trouble keeping the scroll position in sync. Runnable demo project provided. I would like to dynamically add items to a list based on the values in a CursorAdapter, several positions ahead of what the user is currently viewing. To do this, I have an adapter that wraps the CursorAdapter and keeps the new content indexed in a SparseArray. The ListView needs to be updated when items are added to the custom adapter, but I have met a lot of pitfalls trying to get that to work and would love some advice. The demo project can be downloaded here: http://dl.dropbox.com/u/15334423/DynamicSectionedList.zip In the demo, the headings are added dynamically by looking ahead 10 places to find the correct position where the list items switch to the next letter. Each implementation of notifyDataSetChanged has problems as described: Demo 1 This demo shows the importance of notifyDataSetChanged(). On clicking anything, the app will crash. This is due to some sanity checking in ListView... mItemCount != adapter.getItemCount(). Moral is, we need to notify the list that data has changed. Demo 2 The natural next step is to notify the ListView of changes when changes occur. Unfortunately, doing so while the ListView is scrolling firmly breaks all touch interaction until the app switches out of touch mode. You will need to "fling scroll" far enough to generate new headings in order to notice this. Tapping the screen will not cause the scroll to stop, and once stopped none of the list items will be clickable. This is due to some if (!mDataChanged) { /* do very important stuff */ } code in AbsListView.onTouchEvent(). Demo 3 To fix this, Demo 3 introduces a pendingChanges flag and the custom Adapter gains a notifyDataSetChangedIfNeeded() which can be called by the ListView once it has entered a "safe" state for changes. The first point where changes must be notified is in ListView.layoutChildren(), so I overrode that method to first notify of changes if needed, then call through. Fling past at least one heading then click a list item. This doesn't quite work right, though I'm not totally sure why. Tapping or selecting an item with the keyboard/trackball causes the list to refresh without properly syncing the old position. It scrolls to the top of the list which is not acceptable. Demo 4 The scroll problem in Demo 3 can be conquered, at least in touch mode. By adding a call to notifyDataSetChangedIfNeeded() on touch down, the data change happens to take place at such a time that all touch interaction works as expected and the list position is properly synced. However, I can't find an analog for that when the device is not in touch mode, not to mention the fact that it definitely seems like a hack. The list almost always scrolls back to the top, I can't find out what causes it to occasionally maintain the correct position. Since Android is fighting me at each step of the way, I feel like there should be a better approach. Please try the demo, if any fixes can be applied to get it working that would be great! Many thanks to anyone who can look into this, hopefully if we can get the code working it will be useful for others trying to accomplish the same optimization for lists with headings.

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  • Memory Troubles with UIImagePicker

    - by Dan Ray
    I'm building an app that has several different sections to it, all of which are pretty image-heavy. It ties in with my client's website and they're a "high-design" type outfit. One piece of the app is images uploaded from the camera or the library, and a tableview that shows a grid of thumbnails. Pretty reliably, when I'm dealing with the camera version of UIImagePickerControl, I get hit for low memory. If I bounce around that part of the app for a while, I occasionally and non-repeatably crash with "status:10 (SIGBUS)" in the debugger. On low memory warning, my root view controller for that aspect of the app goes to my data management singleton, cruises through the arrays of cached data, and kills the biggest piece, the image associated with each entry. Thusly: - (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Low Memory Warning" message:@"Cleaning out events data" delegate:nil cancelButtonTitle:@"All right then." otherButtonTitles:nil]; [alert show]; [alert release]; NSInteger spaceSaved; DataManager *data = [DataManager sharedDataManager]; for (Event *event in data.eventList) { spaceSaved += [(NSData *)UIImagePNGRepresentation(event.image) length]; event.image = nil; spaceSaved -= [(NSData *)UIImagePNGRepresentation(event.image) length]; } NSString *titleString = [NSString stringWithFormat:@"Saved %d on event images", spaceSaved]; for (WondrMark *mark in data.wondrMarks) { spaceSaved += [(NSData *)UIImagePNGRepresentation(mark.image) length]; mark.image = nil; spaceSaved -= [(NSData *)UIImagePNGRepresentation(mark.image) length]; } NSString *messageString = [NSString stringWithFormat:@"And total %d on event and mark images", spaceSaved]; NSLog(@"%@ - %@", titleString, messageString); // Relinquish ownership any cached data, images, etc that aren't in use. } As you can see, I'm making a (poor) attempt to eyeball the memory space I'm freeing up. I know it's not telling me about the actual memory footprint of the UIImages themselves, but it gives me SOME numbers at least, so I can see that SOMETHING'S happening. (Sorry for the hamfisted way I build that NSLog message too--I was going to fire another UIAlertView, but realized it'd be more useful to log it.) Pretty reliably, after toodling around in the image portion of the app for a while, I'll pull up the camera interface and get the low memory UIAlertView like three or four times in quick succession. Here's the NSLog output from the last time I saw it: 2010-05-27 08:55:02.659 EverWondr[7974:207] Saved 109591 on event images - And total 1419756 on event and mark images wait_fences: failed to receive reply: 10004003 2010-05-27 08:55:08.759 EverWondr[7974:207] Saved 4 on event images - And total 392695 on event and mark images 2010-05-27 08:55:14.865 EverWondr[7974:207] Saved 4 on event images - And total 873419 on event and mark images 2010-05-27 08:55:14.969 EverWondr[7974:207] Saved 4 on event images - And total 4 on event and mark images 2010-05-27 08:55:15.064 EverWondr[7974:207] Saved 4 on event images - And total 4 on event and mark images And then pretty soon after that we get our SIGBUS exit. So that's the situation. Now my specific questions: THE time I see this happening is when the UIPickerView's camera iris shuts. I click the button to take the picture, it does the "click" animation, and Instruments shows my memory footprint going from about 10mb to about 25mb, and sitting there until the image is delivered to my UIViewController, where usage drops back to 10 or 11mb again. If we make it through that without a memory warning, we're golden, but most likely we don't. Anything I can do to make that not be so expensive? Second, I have NSZombies enabled. Am I understanding correctly that that's actually preventing memory from being freed? Am I subjecting my app to an unfair test environment? Third, is there some way to programmatically get my memory usage? Or at least the usage for a UIImage object? I've scoured the docs and don't see anything about that.

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  • Recommended ASP.NET Shared Hosting (USA)

    - by coffeeaddict
    Ok, I have to admit I'm getting fed up with www.discountasp.net's pricing model and this annoyance has built up over the past 8 years or so. I've been with them for years and absolutely love them on the technical side, however it's getting ridiculously expensive for so little that you get. I mean here's my scenario: 1) I am running 2 SQL Server databases which costs me $10/ea per month so that's $20/month for 2 and I only get 500 mb disk space which is horrible 2) I am paying $10/mo just for the hosting itself which I only get 1 gig of disk space! I mean common! 3) I am simply running 2 small apps (Screwturn Wiki & Subtext Blog)...so I don't really care if it's up 99% or not, it's not worth paying a total of $300 just to keep these 2 apps running over discountasp.net Anyone else feel the same? Yes, I know they have great support, probably have great servers running behind this but in the end I really don't care as long as my site is up 95% or better. Yes, the hosting toolset rocks. But you know I bet you I can find a similar set somewhere else. I like how I can totally control IIS 7 at discountasp and I can control my own app pool etc. That's very powerful and essential. But anyone have any good alternatives to discountasp that gives me close to the same at a much more reasonable cost point? I mean http://www.m6.net/prices.aspx gives you 10 SQL Databases for $7 and 200 gigs disk space! I don't know about their tools or support but just looking at those numbers and some other hosts I've seen, I feel that discountasp.net is way out of line. They don't even offer any purchasing discounts such as it would be nice if my 2nd SQL Server is only $5/month not $10...stuff like this, to make it much more realistic and fair. Opinions (people who do have discountasp.net, people who have left them, or people who have another host they like)??? But geez $300 just to host a couple DBs and lightweight open source apps? Not worth the price they are charging. I'm almost at a price point that enables me to get a decent dedicated server! I really don't care about beta ASP.NET frameworks support. Not a big deal to me. If you have alternative suggestions rather than your experience with discountasp, I'd like to know how their toolset is. Do you have complete control over your DB in terms of adding users, and same goes for the web app pool, etc.? Discountasp.net's control panel rocks. I don't want to loose the ability to at least control and add virtual directories, recycle my dedicated app pool myself, backup my sql database myself, through tools which is what discountasp does give you. I'd also want to know that the hoster at least gets the latest and greatest in terms of non-beta ASP.NET related frameworks available to its shared hosters.

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  • CSS/JavaScript/hacking: Detect :visited styling on a link *without* checking it directly OR do it fa

    - by Sai Emrys
    This is for research purposes on http://cssfingerprint.com Consider the following code: <style> div.csshistory a { display: none; color: #00ff00;} div.csshistory a:visited { display: inline; color: #ff0000;} </style> <div id="batch" class="csshistory"> <a id="1" href="http://foo.com">anything you want here</a> <a id="2" href="http://bar.com">anything you want here</a> [etc * ~2000] </div> My goal is to detect whether foo has been rendered using the :visited styling. I want to detect whether foo.com is visited without directly looking at $('1').getComputedStyle (or in Internet Explorer, currentStyle), or any other direct method on that element. The purpose of this is to get around a potential browser restriction that would prevent direct inspection of the style of visited links. For instance, maybe you can put a sub-element in the <a> tag, or check the styling of the text directly; etc. Any method that does not directly or indierctly rely on $('1').anything is acceptable. Doing something clever with the child or parent is probably necessary. Note that for the purposes of this point only, the scenario is that the browser will lie to JavaScript about all properties of the <a> element (but not others), and that it will only render color: in :visited. Therefore, methods that rely on e.g. text size or background-image will not meet this requirement. I want to improve the speed of my current scraping methods. The majority of time (at least with the jQuery method in Firefox) is spent on document.body.appendChild(batch), so finding a way to improve that call would probably most effective. See http://cssfingerprint.com/about and http://cssfingerprint.com/results for current speed test results. The methods I am currently using can be seen at http://github.com/saizai/cssfingerprint/blob/master/public/javascripts/history_scrape.js To summarize for tl;dr, they are: set color or display on :visited per above, and check each one directly w/ getComputedStyle put the ID of the link (plus a space) inside the <a> tag, and using jQuery's :visible selector, extract only the visible text (= the visited link IDs) FWIW, I'm a white hat, and I'm doing this in consultation with the EFF and some other fairly well known security researchers. If you contribute a new method or speedup, you'll get thanked at http://cssfingerprint.com/about (if you want to be :-P), and potentially in a future published paper. ETA: The bounty will be rewarded only for suggestions that can, on Firefox, avoid the hypothetical restriction described in point 1 above, or perform at least 10% faster, on any browser for which I have sufficient current data, than my best performing methods listed in the graph at http://cssfingerprint.com/about In case more than one suggestion fits either criterion, the one that does best wins.

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  • Optimal storage of data structure for fast lookup and persistence

    - by Mikael Svenson
    Scenario I have the following methods: public void AddItemSecurity(int itemId, int[] userIds) public int[] GetValidItemIds(int userId) Initially I'm thinking storage on the form: itemId -> userId, userId, userId and userId -> itemId, itemId, itemId AddItemSecurity is based on how I get data from a third party API, GetValidItemIds is how I want to use it at runtime. There are potentially 2000 users and 10 million items. Item id's are on the form: 2007123456, 2010001234 (10 digits where first four represent the year). AddItemSecurity does not have to perform super fast, but GetValidIds needs to be subsecond. Also, if there is an update on an existing itemId I need to remove that itemId for users no longer in the list. I'm trying to think about how I should store this in an optimal fashion. Preferably on disk (with caching), but I want the code maintainable and clean. If the item id's had started at 0, I thought about creating a byte array the length of MaxItemId / 8 for each user, and set a true/false bit if the item was present or not. That would limit the array length to little over 1mb per user and give fast lookups as well as an easy way to update the list per user. By persisting this as Memory Mapped Files with the .Net 4 framework I think I would get decent caching as well (if the machine has enough RAM) without implementing caching logic myself. Parsing the id, stripping out the year, and store an array per year could be a solution. The ItemId - UserId[] list can be serialized directly to disk and read/write with a normal FileStream in order to persist the list and diff it when there are changes. Each time a new user is added all the lists have to updated as well, but this can be done nightly. Question Should I continue to try out this approach, or are there other paths which should be explored as well? I'm thinking SQL server will not perform fast enough, and it would give an overhead (at least if it's hosted on a different server), but my assumptions might be wrong. Any thought or insights on the matter is appreciated. And I want to try to solve it without adding too much hardware :) [Update 2010-03-31] I have now tested with SQL server 2008 under the following conditions. Table with two columns (userid,itemid) both are Int Clustered index on the two columns Added ~800.000 items for 180 users - Total of 144 million rows Allocated 4gb ram for SQL server Dual Core 2.66ghz laptop SSD disk Use a SqlDataReader to read all itemid's into a List Loop over all users If I run one thread it averages on 0.2 seconds. When I add a second thread it goes up to 0.4 seconds, which is still ok. From there on the results are decreasing. Adding a third thread brings alot of the queries up to 2 seonds. A forth thread, up to 4 seconds, a fifth spikes some of the queries up to 50 seconds. The CPU is roofing while this is going on, even on one thread. My test app takes some due to the speedy loop, and sql the rest. Which leads me to the conclusion that it won't scale very well. At least not on my tested hardware. Are there ways to optimize the database, say storing an array of int's per user instead of one record per item. But this makes it harder to remove items.

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  • Allocation algorithm help, using Python.

    - by Az
    Hi there, I've been working on this general allocation algorithm for students. The pseudocode for it (a Python implementation) is: for a student in a dictionary of students: for student's preference in a set of preferences (ordered from 1 to 10): let temp_project be the first preferred project check if temp_project is available if so, allocate it to them and make the project UNavailable to others Quite simply this will try to allocate projects by starting from their most preferred. The way it works, out of a set of say 100 projects, you list 10 you would want to do. So the 10th project wouldn't be the "least preferred overall" but rather the least preferred in their chosen set, which isn't so bad. Obviously if it can't allocate a project, a student just reverts to the base case which is an allocation of None, with a rank of 11. What I'm doing is calculating the allocation "quality" based on a weighted sum of the ranks. So the lower the numbers (i.e. more highly preferred projects), the better the allocation quality (i.e. more students have highly preferred projects). That's basically what I've currently got. Simple and it works. Now I'm working on this algorithm that tries to minimise the allocation weight locally (this pseudocode is a bit messy, sorry). The only reason this will probably work is because my "search space" as it is, isn't particularly large (just a very general, anecdotal observation, mind you). Since the project is only specific to my Department, we have their own limits imposed. So the number of students can't exceed 100 and the number of preferences won't exceed 10. for student in a dictionary/list/whatever of students: where i = 0 take the (i)st student, (i+1)nd student for their ranks: allocate the projects and set local_weighting to be sum(student_i.alloc_proj_rank, student_i+1.alloc_proj_rank) these are the cases: if local_weighting is 2 (i.e. both ranks are 1): then i += 1 and and continue above if local weighting is = N>2 (i.e. one or more ranks are greater than 1): let temp_local_weighting be N: pick student with lowest rank and then move him to his next rank and pick the other student and reallocate his project after this if temp_local_weighting is < N: then allocate those projects to the students move student with lowest rank to the next rank and reallocate other if temp_local_weighting < previous_temp_allocation: let these be the new allocated projects try moving for the lowest rank and reallocate other else: if this weighting => previous_weighting let these be the allocated projects i += 1 and move on for the rest of the students So, questions: This is sort of a modification of simulated annealing, but any sort of comments on this would be appreciated. How would I keep track of which student is (i) and which student is (i+1) If my overall list of students is 100, then the thing would mess up on (i+1) = 101 since there is none. How can I circumvent that? Any immediate flaws that can be spotted? Extra info: My students dictionary is designed as such: students[student_id] = Student(student_id, student_name, alloc_proj, alloc_proj_rank, preferences) where preferences is in the form of a dictionary such that preferences[rank] = {project_id}

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  • C#: Inheritence, Overriding, and Hiding

    - by Rosarch
    I'm having difficulty with an architectural decision for my C# XNA game. The basic entity in the world, such as a tree, zombie, or the player, is represented as a GameObject. Each GameObject is composed of at least a GameObjectController, GameObjectModel, and GameObjectView. These three are enough for simple entities, like inanimate trees or rocks. However, as I try to keep the functionality as factored out as possible, the inheritance begins to feel unwieldy. Syntactically, I'm not even sure how best to accomplish my goals. Here is the GameObjectController: public class GameObjectController { protected GameObjectModel model; protected GameObjectView view; public GameObjectController(GameObjectManager gameObjectManager) { this.gameObjectManager = gameObjectManager; model = new GameObjectModel(this); view = new GameObjectView(this); } public GameObjectManager GameObjectManager { get { return gameObjectManager; } } public virtual GameObjectView View { get { return view; } } public virtual GameObjectModel Model { get { return model; } } public virtual void Update(long tick) { } } I want to specify that each subclass of GameObjectController will have accessible at least a GameObjectView and GameObjectModel. If subclasses are fine using those classes, but perhaps are overriding for a more sophisticated Update() method, I don't want them to have to duplicate the code to produce those dependencies. So, the GameObjectController constructor sets those objects up. However, some objects do want to override the model and view. This is where the trouble comes in. Some objects need to fight, so they are CombatantGameObjects: public class CombatantGameObject : GameObjectController { protected new readonly CombatantGameModel model; public new virtual CombatantGameModel Model { get { return model; } } protected readonly CombatEngine combatEngine; public CombatantGameObject(GameObjectManager gameObjectManager, CombatEngine combatEngine) : base(gameObjectManager) { model = new CombatantGameModel(this); this.combatEngine = combatEngine; } public override void Update(long tick) { if (model.Health <= 0) { gameObjectManager.RemoveFromWorld(this); } base.Update(tick); } } Still pretty simple. Is my use of new to hide instance variables correct? Note that I'm assigning CombatantObjectController.model here, even though GameObjectController.Model was already set. And, combatants don't need any special view functionality, so they leave GameObjectController.View alone. Then I get down to the PlayerController, at which a bug is found. public class PlayerController : CombatantGameObject { private readonly IInputReader inputReader; private new readonly PlayerModel model; public new PlayerModel Model { get { return model; } } private float lastInventoryIndexAt; private float lastThrowAt; public PlayerController(GameObjectManager gameObjectManager, IInputReader inputReader, CombatEngine combatEngine) : base(gameObjectManager, combatEngine) { this.inputReader = inputReader; model = new PlayerModel(this); Model.Health = Constants.PLAYER_HEALTH; } public override void Update(long tick) { if (Model.Health <= 0) { gameObjectManager.RemoveFromWorld(this); for (int i = 0; i < 10; i++) { Debug.WriteLine("YOU DEAD SON!!!"); } return; } UpdateFromInput(tick); // .... } } The first time that this line is executed, I get a null reference exception: model.Body.ApplyImpulse(movementImpulse, model.Position); model.Position looks at model.Body, which is null. This is a function that initializes GameObjects before they are deployed into the world: public void Initialize(GameObjectController controller, IDictionary<string, string> data, WorldState worldState) { controller.View.read(data); controller.View.createSpriteAnimations(data, _assets); controller.Model.read(data); SetUpPhysics(controller, worldState, controller.Model.BoundingCircleRadius, Single.Parse(data["x"]), Single.Parse(data["y"]), bool.Parse(data["isBullet"])); } Every object is passed as a GameObjectController. Does that mean that if the object is really a PlayerController, controller.Model will refer to the base's GameObjectModel and not the PlayerController's overriden PlayerObjectModel?

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  • Keyboard for programming

    - by exhuma
    This may seem a bit a tangential topic. It's not directly related to actual code, but is important for our line of work nevertheless. Over the years, I've switched keyboards a few times. All of them had slightly different key layouts. And I'm not talking about the language/locale layout, but the physical layout! Why not the locale layout? Well, quite frankly, that's easy to change via software. I personally have a German keyboard but have it set to the UK layout. Why? It's quite hard to find different layouts in the shops where I live. Even ordering is not always easy in the shops. So that leaves me with Internet shops. But I prefer to "test" my keyboards before buying. The most notable changes are: Mangled "Home Key Block" I've seen this first on a Logitech keyboard, but it may have originated elsewhere. Shape of the "Enter" key I've seen three different cases so far: Two lines high, wider at the top Two lines high, wider at the bottom One line high Shape of the Backspace button I've seen two types so far: One "character" wide Two "characters" wide OS Keys For Macs, you have the Option and Command buttons, for Windows you have the Windows and Context Menu buttons. Cherry even produced a Linux keyboard once (unfortunately I cannot find many details except news results). I assume a dedicated Linux keyboard would sport a Compose key and had the SysRq always labelled as well (note that some standard layouts do this already). Obviously... .. all these differences entail that some keys have to be moved around the board a lot. Which means, if you are used to one and have to work on another one, you happen to hit the wrong keys quite often. As it happens, this is much more annoying for programmers as it is for people who write texts. Mainly because the keys which are moved around are special character keys, often used in programming. Often these hardware layouts depend also indirectly on where you buy the keyboards. Honestly, I haven't seen a keyboard with a one-line "Enter" key in Germany, nor Luxembourg. I may just have missed it but that's how it looks to me at least. A survey I've seen some attempts at surveys in the style "which keyboard is best for programming". But they all - in my opinion - are not using comparable sets. So I was wondering if it was possible to concoct a survey taking the above criteria into account. But ignoring key dimensions that one would be a bit overkill I guess ;) From what I can see there are the following types of physical layout: Backspace: 2-characters wide Enter: 2-Lines, wider top Backspace: 2-characters wide Enter: 1-Line Backspace: 1-character wide Enter: 2-Lines, wider bottom Then there are the other possible permutations (home-key block, os-keys), which in total makes for quite a large list of categories. Now, I wonder... Would anyone be interested in such a survey? I personally would. Because I am looking for the perfect fit for me. If yes, then I could really use the help of anyone here to propose some models to include in the survey. Once I have some models for each category (I'd say at least 3 per category) I could go ahead and write up a survey, put it on-line and let the it collect data for a while. What do you think?

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  • Make c# matrix code faster

    - by Wam
    Hi all, Working on some matrix code, I'm concerned of performance issues. here's how it works : I've a IMatrix abstract class (with all matrices operations etc), implemented by a ColumnMatrix class. abstract class IMatrix { public int Rows {get;set;} public int Columns {get;set;} public abstract float At(int row, int column); } class ColumnMatrix : IMatrix { private data[]; public override float At(int row, int column) { return data[row + columns * this.Rows]; } } This class is used a lot across my application, but I'm concerned with performance issues. Testing only read for a 2000000x15 matrix against a jagged array of the same size, I get 1359ms for array access agains 9234ms for matrix access : public void TestAccess() { int iterations = 10; int rows = 2000000; int columns = 15; ColumnMatrix matrix = new ColumnMatrix(rows, columns); for (int i = 0; i < rows; i++) for (int j = 0; j < columns; j++) matrix[i, j] = i + j; float[][] equivalentArray = matrix.ToRowsArray(); TimeSpan totalMatrix = new TimeSpan(0); TimeSpan totalArray = new TimeSpan(0); float total = 0f; for (int iteration = 0; iteration < iterations; iteration++) { total = 0f; DateTime start = DateTime.Now; for (int i = 0; i < rows; i++) for (int j = 0; j < columns; j++) total = matrix.At(i, j); totalMatrix += (DateTime.Now - start); total += 1f; //Ensure total is read at least once. total = total > 0 ? 0f : 0f; start = DateTime.Now; for (int i = 0; i < rows; i++) for (int j = 0; j < columns; j++) total = equivalentArray[i][j]; totalArray += (DateTime.Now - start); } if (total < 0f) logger.Info("Nothing here, just make sure we read total at least once."); logger.InfoFormat("Average time for a {0}x{1} access, matrix : {2}ms", rows, columns, totalMatrix.TotalMilliseconds); logger.InfoFormat("Average time for a {0}x{1} access, array : {2}ms", rows, columns, totalArray.TotalMilliseconds); Assert.IsTrue(true); } So my question : how can I make this thing faster ? Is there any way I can make my ColumnMatrix.At faster ? Cheers !

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  • Please recommend me intermediate-to-advanced Python books to buy.

    - by anonnoir
    I'm in the final year, final semester of my law degree, and will be graduating very soon. (April, to be specific.) But before I begin practice, I plan to take 2 two months off, purely for serious programming study. So I'm currently looking for some Python-related books, gauged intermediate to advanced, which are interesting (because of the subject matter itself) and possibly useful to my future line of work. I've identified 2 possible purchases at the moment: Natural Language Processing with Python. The law deals mostly with words, and I've quite a number of ideas as to where I might go with NLP. Data extraction, summaries, client management systems linked with document templates, etc. Programming Collective Intelligence. This book fascinates me, because I've always liked the idea of machine learning (and I'm currently studying it by the side too, for fun). I'd like to build/play around with Web 2.0 applications; and who knows if I can apply some of the things I learn to my legal work. (E.g. Playground experiments to determine how and under what circumstances judges might be biased, by forcing algorithms to pore through judgments and calculate similarities, etc.) Please feel free to criticize my current choices, but do at least offer or recommend other books that I should read in their place. My budget can deal with 4 books, max. These books will be used heavily throughout the 2 months; I will be reading them back to back, absorbing the explanations given, and hacking away at their code. Also, the books themselves should satisfy 2 main criteria: Application. The book must teach how to solve problems. I like reading theory, but I want to build things and solve problems first. Even playful applications are fine, because games and experiments always have real-world applications sooner or later. Readability. I like reading technical books, no matter how difficult they are. I enjoy the effort and the feeling that you're learning something. But the book shouldn't contain code or explanations that are too cryptic or erratic. Even if it's difficult, the book's content should be accessible with focused reading. Note: I realize that I am somewhat of a beginner to the whole programming thing, so please don't put me down. But from experience, I think it's better to aim up and leave my comfort zone when learning new things, rather than to just remain stagnant the way I am. (At least the difficulty gives me focus: i.e. if a programmer can be that good, perhaps if I sustain my own efforts I too can be as good as him someday.) If anything, I'm also a very determined person, so two months of day-to-night intensive programming study with nothing else on my mind should, I think, give me a bit of a fighting chance to push my programming skills to a much higher level.

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  • Why is there a Null Pointer Exception in this Java Code?

    - by algorithmicCoder
    This code takes in users and movies from two separate files and computes a user score for a movie. When i run the code I get the following error: Exception in thread "main" java.lang.NullPointerException at RecommenderSystem.makeRecommendation(RecommenderSystem.java:75) at RecommenderSystem.main(RecommenderSystem.java:24) I believe the null pointer exception is due to an error in this particular class but I can't spot it....any thoughts? import java.io.*; import java.lang.Math; public class RecommenderSystem { private Movie[] m_movies; private User[] m_users; /** Parse the movies and users files, and then run queries against them. */ public static void main(String[] argv) throws FileNotFoundException, ParseError, RecommendationError { FileReader movies_fr = new FileReader("C:\\workspace\\Recommender\\src\\IMDBTop10.txt"); FileReader users_fr = new FileReader("C:\\workspace\\Recommender\\src\\IMDBTop10-users.txt"); MovieParser mp = new MovieParser(movies_fr); UserParser up = new UserParser(users_fr); Movie[] movies = mp.getMovies(); User[] users = up.getUsers(); RecommenderSystem rs = new RecommenderSystem(movies, users); System.out.println("Alice would rate \"The Shawshank Redemption\" with at least a " + rs.makeRecommendation("The Shawshank Redemption", "asmith")); System.out.println("Carol would rate \"The Dark Knight\" with at least a " + rs.makeRecommendation("The Dark Knight", "cd0")); } /** Instantiate a recommender system. * * @param movies An array of Movie that will be copied into m_movies. * @param users An array of User that will be copied into m_users. */ public RecommenderSystem(Movie[] movies, User[] users) throws RecommendationError { m_movies = movies; m_users = users; } /** Suggest what the user with "username" would rate "movieTitle". * * @param movieTitle The movie for which a recommendation is made. * @param username The user for whom the recommendation is made. */ public double makeRecommendation(String movieTitle, String username) throws RecommendationError { int userNumber; int movieNumber; int j=0; double weightAvNum =0; double weightAvDen=0; for (userNumber = 0; userNumber < m_users.length; ++userNumber) { if (m_users[userNumber].getUsername().equals(username)) { break; } } for (movieNumber = 0; movieNumber < m_movies.length; ++movieNumber) { if (m_movies[movieNumber].getTitle().equals(movieTitle)) { break; } } // Use the weighted average algorithm here (don't forget to check for // errors). while(j<m_users.length){ if(j!=userNumber){ weightAvNum = weightAvNum + (m_users[j].getRating(movieNumber)- m_users[j].getAverageRating())*(m_users[userNumber].similarityTo(m_users[j])); weightAvDen = weightAvDen + (m_users[userNumber].similarityTo(m_users[j])); } j++; } return (m_users[userNumber].getAverageRating()+ (weightAvNum/weightAvDen)); } } class RecommendationError extends Exception { /** An error for when something goes wrong in the recommendation process. * * @param s A string describing the error. */ public RecommendationError(String s) { super(s); } }

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  • Is it possible to shuffle a 2D matrix while preserving row AND column frequencies?

    - by j_random_hacker
    Suppose I have a 2D array like the following: GACTG AGATA TCCGA Each array element is taken from a small finite set (in my case, DNA nucleotides -- {A, C, G, T}). I would like to randomly shuffle this array somehow while preserving both row and column nucleotide frequencies. Is this possible? Can it be done efficiently? [EDIT]: By this I mean I want to produce a new matrix where each row has the same number of As, Cs, Gs and Ts as the corresponding row of the original matrix, and where each column has the same number of As, Cs, Gs and Ts as the corresponding column of the original matrix. Permuting the rows or columns of the original matrix will not achieve this in general. (E.g. for the example above, the top row has 2 Gs, and 1 each of A, C and T; if this row was swapped with row 2, the top row in the resulting matrix would have 3 As, 1 G and 1 T.) It's simple enough to preserve just column frequencies by shuffling a column at a time, and likewise for rows. But doing this will in general alter the frequencies of the other kind. My thoughts so far: If it's possible to pick 2 rows and 2 columns so that the 4 elements at the corners of this rectangle have the pattern XY YX for some pair of distinct elements X and Y, then replacing these 4 elements with YX XY will maintain both row and column frequencies. In the example at the top, this can be done for (at least) rows 1 and 2 and columns 2 and 5 (whose corners give the 2x2 matrix AG;GA), and for rows 1 and 3 and columns 1 and 4 (whose corners give GT;TG). Clearly this could be repeated a number of times to produce some level of randomisation. Generalising a bit, any "subrectangle" induced by a subset of rows and a subset of columns, in which the frequencies of all rows are the same and the frequencies of all columns are the same, can have both its rows and columns permuted to produce a valid complete rectangle. (Of these, only those subrectangles in which at least 1 element is changed are actually interesting.) Big questions: Are all valid complete matrices reachable by a series of such "subrectangle rearrangements"? I suspect the answer is yes. Are all valid subrectangle rearrangements decomposable into a series of 2x2 swaps? I suspect the answer is no, but I hope it's yes, since that would seem to make it easier to come up with an efficient algorithm. Can some or all of the valid rearrangements be computed efficiently? This question addresses a special case in which the set of possible elements is {0, 1}. The solutions people have come up with there are similar to what I have come up with myself, and are probably usable, but not ideal as they require an arbitrary amount of backtracking to work correctly. Also I'm concerned that only 2x2 swaps are considered. Finally, I would ideally like a solution that can be proven to select a matrix uniformly at random from the set of all matrices having identical row frequencies and column frequencies to the original. I know, I'm asking for a lot :)

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  • HTML 5 <video> tag vs Flash video. What are the pros and cons?

    - by Vilx-
    Seems like the new <video> tag is all the hype these days, especially since Firefox now supports it. News of this are popping up in blogs all over the place, and everyone seems to be excited. But what about? As much as I searched I could not find anything that would make it better than the good old Flash video. In fact, I see only problems with it: It will still be some time before all the browsers start supporting it, and much more time before most people upgrade; Flash is available already and everyone has it; You can couple Flash with whatever fancy UI you want for controlling the playback. I gather that the tag will be controllable as well (via JavaScript probably), but will it be able to go fullscreen? The only two pros for a <video> tag that I can see are: It is more "semantic" - which probably holds no importance to a whole lot of people, including me; It is not dependent on a single commercial 3rd party entity (Adobe) - which I also don't see as a compelling reason to switch, because free players and video converters are already available, and Adobe is not hindering the whole process in any way (it's not in their interests even). So... what's the big deal? Added: OK, so there is one more Pro... maybe. Support for mobile devices. Hard to say though. A number of thoughts race through my head about the subject: How many mobile devices are actually able to decode video at a decent speed anyway, Flash or otherwise? How long until mainstream mobile devices get the <video> support? Even if it is available through updates, how many people actually do that? How many people watch videos on web pages on their mobile phones at all? As for the semantics part - I understand that search engines might be able to detect videos better now, but... what will they do with them anyway? OK, so they know that there is a video in the page. And? They can't index a video! I'd like some more arguments here. Added: Just thought of another Cons. This opens up a whole new area of cross-browser incompatibility. HTML and CSS is quite messy already in this aspect. Flash at least is the same everywhere. But it's enough for at least one major browser vendor to decide against the <video> tag (can anyone say "Internet Explorer"?) and we have a nice new area of hell to explore. Added: A Pro just came in. More competition = more innovation. That's true. Giving Adobe more competition will probably force them to improve Flash in areas it has been lacking so far. Linux seems to be a weak spot for it, cited by many.

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  • Please clarify how create/update happens against child entities of an aggregate root

    - by christian
    After much reading and thinking as I begin to get my head wrapped around DDD, I am a bit confused about the best practices for dealing with complex hierarchies under an aggregate root. I think this is a FAQ but after reading countless examples and discussions, no one is quite talking about the issue I'm seeing. If I am aligned with the DDD thinking, entities below the aggregate root should be immutable. This is the crux of my trouble, so if that isn't correct, that is why I'm lost. Here is a fabricated example...hope it holds enough water to discuss. Consider an automobile insurance policy (I'm not in insurance, but this matches the language I hear when on the phone w/ my insurance company). Policy is clearly an entity. Within the policy, let's say we have Auto. Auto, for the sake of this example, only exists within a policy (maybe you could transfer an Auto to another policy, so this is potential for an aggregate as well, which changes Policy...but assume it simpler than that for now). Since an Auto cannot exist without a Policy, I think it should be an Entity but not a root. So Policy in this case is an aggregate root. Now, to create a Policy, let's assume it has to have at least one auto. This is where I get frustrated. Assume Auto is fairly complex, including many fields and maybe a child for where it is garaged (a Location). If I understand correctly, a "create Policy" constructor/factory would have to take as input an Auto or be restricted via a builder to not be created without this Auto. And the Auto's creation, since it is an entity, can't be done beforehand (because it is immutable? maybe this is just an incorrect interpretation). So you don't get to say new Auto and then setX, setY, add(Z). If Auto is more than somewhat trivial, you end up having to build a huge hierarchy of builders and such to try to manage creating an Auto within the context of the Policy. One more twist to this is later, after the Policy is created and one wishes to add another Auto...or update an existing Auto. Clearly, the Policy controls this...fine...but Policy.addAuto() won't quite fly because one can't just pass in a new Auto (right!?). Examples say things like Policy.addAuto(VIN, make, model, etc.) but are all so simple that that looks reasonable. But if this factory method approach falls apart with too many parameters (the entire Auto interface, conceivably) I need a solution. From that point in my thinking, I'm realizing that having a transient reference to an entity is OK. So, maybe it is fine to have a entity created outside of its parent within the aggregate in a transient environment, so maybe it is OK to say something like: auto = AutoFactory.createAuto(); auto.setX auto.setY or if sticking to immutability, AutoBuilder.new().setX().setY().build() and then have it get sorted out when you say Policy.addAuto(auto) This insurance example gets more interesting if you add Events, such as an Accident with its PolicyReports or RepairEstimates...some value objects but most entities that are all really meaningless outside the policy...at least for my simple example. The lifecycle of Policy with its growing hierarchy over time seems the fundamental picture I must draw before really starting to dig in...and it is more the factory concept or how the child entities get built/attached to an aggregate root that I haven't seen a solid example of. I think I'm close. Hope this is clear and not just a repeat FAQ that has answers all over the place.

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  • Radio Button Validation u

    - by Sirojan Gnanaretnam
    I am trying validate the radio button using Javascript . But I couldn't get it. Can any one please help me to fix this Issue. I Have attached My Code Below. Thanks. <form action="submitAd.php" method="POST" enctype="multipart/form-data" name="packages" onsubmit="return checkForm()"> <div id="plans_pay"> <input type="radio" name="group1" id="r1" value="Office" onchange="click_Pay_Office()" style="float:left;margin-top:20px;font-size:72px;"> <label style="float:left; margin-top:20px;" for="pay_office">At Our Office</label> <img style="float:left;margin-bottom:10px;" src="images/Pay-at-office.png" /> </div> <div id="plans_pay"> <input style="float:left;margin-top:20px;font-size:72px;" type="radio" name="group1" id="r2" value="HNB" onchange="click_Pay_Hnb()"> <label style="float:left; margin-top:20px;" for="pay_hnb">At Any HNB Branch</label> <img style="float:left;margin-bottom:10px;" src="images/HNB.png" /> </div> </form> Javascript function checkForm(){ if( document.packages.pso.checked == false && document.packages.pso1.checked == false && document.packages.ph.checked == false && document.packages.ph2.checked == false && document.packages.ph3.checked == false && document.packages.pl.checked == false && document.packages.p3.checked == false && document.packages.p4.checked == false && document.packages.p5.checked == false && document.packages.p6.checked == false ){ alert('Please Select At Least One Package'); return false; } if( document.packages.pso.checked == false && document.packages.pso1.checked == false && document.packages.ph.checked == false && document.packages.ph.checked == false && document.packages.ph2.checked == false && document.packages.ph3.checked == false && document.packages.pl.checked == false && document.packages.p3.checked == false && document.packages.p4.checked == false && document.packages.p5.checked == false && document.packages.p6.checked == false){ alert('Please Select At Least One with the Advertise online option in premium package'); return false; } if(document.getElementById('words').value==''){ alert("Please Enter the Texts"); return false; } if(document.getElementById('r1').checked==false && document.getElementById('r2').checked==false){ alert("Please Select a Payment Method"); return false; } }

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  • backtracking in haskell

    - by dmindreader
    I have to traverse a matrix and say how many "characteristic areas" of each type it has. A characteristic area is defined as a zone where elements of value n or n are adjacent. For example, given the matrix: 0 1 2 2 0 1 1 2 0 3 0 0 There's a single characteristic area of type 1 which is equal to the original matrix: 0 1 2 2 0 1 1 2 0 3 0 0 There are two characteristic areas of type 2: 0 0 2 2 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 3 0 0 And one characteristic area of type 3: 0 0 0 0 0 0 0 0 0 3 0 0 So, for the function call: countAreas [[0,1,2,2],[0,1,1,2],[0,3,0,0]] The result should be [1,2,1] I haven't defined countAreas yet, I'm stuck with my visit function when it has no more possible squares in which to move it gets stuck and doesn't make the proper recursive call. I'm new to functional programming and I'm still scratching my head about how to implement a backtracking algorithm here. Take a look at my code, what can I do to change it? move_right :: (Int,Int) -> [[Int]] -> Int -> Bool move_right (i,j) mat cond | (j + 1) < number_of_columns mat && consult (i,j+1) mat /= cond = True | otherwise = False move_left :: (Int,Int) -> [[Int]] -> Int -> Bool move_left (i,j) mat cond | (j - 1) >= 0 && consult (i,j-1) mat /= cond = True | otherwise = False move_up :: (Int,Int) -> [[Int]] -> Int -> Bool move_up (i,j) mat cond | (i - 1) >= 0 && consult (i-1,j) mat /= cond = True | otherwise = False move_down :: (Int,Int) -> [[Int]] -> Int -> Bool move_down (i,j) mat cond | (i + 1) < number_of_rows mat && consult (i+1,j) mat /= cond = True | otherwise = False imp :: (Int,Int) -> Int imp (i,j) = i number_of_rows :: [[Int]] -> Int number_of_rows i = length i number_of_columns :: [[Int]] -> Int number_of_columns (x:xs) = length x consult :: (Int,Int) -> [[Int]] -> Int consult (i,j) l = (l !! i) !! j visited :: (Int,Int) -> [(Int,Int)] -> Bool visited x y = elem x y add :: (Int,Int) -> [(Int,Int)] -> [(Int,Int)] add x y = x:y visit :: (Int,Int) -> [(Int,Int)] -> [[Int]] -> Int -> [(Int,Int)] visit (i,j) vis mat cond | move_right (i,j) mat cond && not (visited (i,j+1) vis) = visit (i,j+1) (add (i,j+1) vis) mat cond | move_down (i,j) mat cond && not (visited (i+1,j) vis) = visit (i+1,j) (add (i+1,j) vis) mat cond | move_left (i,j) mat cond && not (visited (i,j-1) vis) = visit (i,j-1) (add (i,j-1) vis) mat cond | move_up (i,j) mat cond && not (visited (i-1,j) vis) = visit (i-1,j) (add (i-1,j) vis) mat cond | otherwise = vis

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  • Maze not being random.

    - by Matt Habel
    Hey there, I am building a program that generates a maze so I can later translate the path to my graphical part. I have most of it working, however, every time you can just take the east and south routes, and you'll get to the end. Even if I set the width as high as 64, so the maze is 64*64, I'm able to choose those 2 options and get to the end every time. I really don't understand why it is doing that. The code is below, it's fairly easy to understand. import random width = 8 def check(x,y): """Figures out the directions that Gen can move while""" if x-1 == -1: maze[x][y][3] = 0 if x+1 == width + 1: maze[x][y][1] = 0 if y+1 == width + 1: maze[x][y][2] = 0 if y-1 == -1: maze[x][y][0] = 0 if x + 1 in range(0,width) and visited[x+1][y] == False: maze[x][y][1] = 2 if x - 1 in range(0,width) and visited[x-1][y] == False: maze[x][y][3] = 2 if y + 1 in range(0,width) and visited[x][y+1] == False: maze[x][y][2] = 2 if y - 1 in range(0,width) and visited[x][y-1] == False: maze[x][y][0] = 2 def possibleDirs(x,y): """Figures out the ways that the person can move in each square""" dirs = [] walls = maze[x][y] if walls[0] == 1: dirs.append('n') if walls[1] == 1: dirs.append('e') if walls[2] == 1: dirs.append('s') if walls[3] == 1: dirs.append('w') return dirs def Gen(x,y): """Generates the maze using a depth-first search and recursive backtracking.""" visited[x][y] = True dirs = [] check(x,y) if maze[x][y][0] == 2: dirs.append(0) if maze[x][y][1] == 2: dirs.append(1) if maze[x][y][2] == 2: dirs.append(2) if maze[x][y][3] == 2: dirs.append(3) print dirs if len(dirs): #Randonly selects a derection for the current square to move past.append(current[:]) pos = random.choice(dirs) maze[x][y][pos] = 1 if pos == 0: current[1] -= 1 maze[x][y-1][2] = 1 if pos == 1: current[0] += 1 maze[x+1][y][3] = 1 if pos == 2: current[1] += 1 maze[x][y+1][0] = 1 if pos == 3: current[0] -= 1 maze[x-1][y][1] = 1 else: #If there's nowhere to go, go back one square lastPlace = past.pop() current[0] = lastPlace[0] current[1] = lastPlace[1] #Build the initial values for the maze to be replaced later maze = [] visited = [] past = [] #Generate empty 2d list with a value for each of the xy coordinates for i in range(0,width): maze.append([]) for q in range(0, width): maze[i].append([]) for n in range(0, 4): maze[i][q].append(4) #Makes a list of falses for all the non visited places for x in range(0, width): visited.append([]) for y in range(0, width): visited[x].append(False) dirs = [] print dirs current = [0,0] #Generates the maze so every single square has been filled. I'm not sure how this works, as it is possible to only go south and east to get to the final position. while current != [width-1, width-1]: Gen(current[0], current[1]) #Getting the ways the person can move in each square for i in range(0,width): dirs.append([]) for n in range(0,width): dirs[i].append([]) dirs[i][n] = possibleDirs(i,n) print dirs print visited pos = [0,0] #The user input part of the maze while pos != [width - 1, width - 1]: dirs = [] print pos if maze[pos[0]][pos[1]][0] == 1: dirs.append('n') if maze[pos[0]][pos[1]][1] == 1: dirs.append('e') if maze[pos[0]][pos[1]][2] == 1: dirs.append('s') if maze[pos[0]][pos[1]][3] == 1: dirs.append('w') print dirs path = raw_input("What direction do you want to go: ") if path not in dirs: print "You can't go that way!" continue elif path.lower() == 'n': pos[1] -= 1 elif path.lower() == 'e': pos[0] += 1 elif path.lower() == 's': pos[1] += 1 elif path.lower() == 'w': pos[0] -= 1 print"Good job!" As you can see, I think the problem is at the point where I generate the maze, however, when I just have it go until the current point is at the end, it doesn't fill every maze and is usually just one straight path. Thanks for helping. Update: I have changed the for loop that generates the maze to a simple while loop and it seems to work much better. It seems that when the for loop ran, it didn't go recursively, however, in the while loop it's perfectly fine. However, now all the squares do not fill out.

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  • Strategy and AI for the game 'Proximity'

    - by smci
    'Proximity' is a strategy game of territorial domination similar to Othello, Go and Risk. Two players, uses a 10x12 hex grid. Game invented by Brian Cable in 2007. Seems to be a worthy game for discussing a) optimal strategy then b) how to build an AI Strategies are going to be probabilistic or heuristic-based, due to the randomness factor, and the high branching factor (starts out at 120). So it will be kind of hard to compare objectively. A compute time limit of 5s per turn seems reasonable. Game: Flash version here and many copies elsewhere on the web Rules: here Object: to have control of the most armies after all tiles have been placed. Each turn you received a randomly numbered tile (value between 1 and 20 armies) to place on any vacant board space. If this tile is adjacent to any ally tiles, it will strengthen each tile's defenses +1 (up to a max value of 20). If it is adjacent to any enemy tiles, it will take control over them if its number is higher than the number on the enemy tile. Thoughts on strategy: Here are some initial thoughts; setting the computer AI to Expert will probably teach a lot: minimizing your perimeter seems to be a good strategy, to prevent flips and minimize worst-case damage like in Go, leaving holes inside your formation is lethal, only more so with the hex grid because you can lose armies on up to 6 squares in one move low-numbered tiles are a liability, so place them away from your main territory, near the board edges and scattered. You can also use low-numbered tiles to plug holes in your formation, or make small gains along the perimeter which the opponent will not tend to bother attacking. a triangle formation of three pieces is strong since they mutually reinforce, and also reduce the perimeter Each tile can be flipped at most 6 times, i.e. when its neighbor tiles are occupied. Control of a formation can flow back and forth. Sometimes you lose part of a formation and plug any holes to render that part of the board 'dead' and lock in your territory/ prevent further losses. Low-numbered tiles are obvious-but-low-valued liabilities, but high-numbered tiles can be bigger liabilities if they get flipped (which is harder). One lucky play with a 20-army tile can cause a swing of 200 (from +100 to -100 armies). So tile placement will have both offensive and defensive considerations. Comment 1,2,4 seem to resemble a minimax strategy where we minimize the maximum expected possible loss (modified by some probabilistic consideration of the value ß the opponent can get from 1..20 i.e. a structure which can only be flipped by a ß=20 tile is 'nearly impregnable'.) I'm not clear what the implications of comments 3,5,6 are for optimal strategy. Interested in comments from Go, Chess or Othello players. (The sequel ProximityHD for XBox Live, allows 4-player -cooperative or -competitive local multiplayer increases the branching factor since you now have 5 tiles in your hand at any given time, of which you can only play one. Reinforcement of ally tiles is increased to +2 per ally.)

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  • Find optimal strategy and AI for the game 'Proximity'?

    - by smci
    'Proximity' is a strategy game of territorial domination similar to Othello, Go and Risk. Two players, uses a 10x12 hex grid. Game invented by Brian Cable in 2007. Seems to be a worthy game for discussing a) optimal algorithm then b) how to build an AI. Strategies are going to be probabilistic or heuristic-based, due to the randomness factor, and the insane branching factor (20^120). So it will be kind of hard to compare objectively. A compute time limit of 5s per turn seems reasonable. Game: Flash version here and many copies elsewhere on the web Rules: here Object: to have control of the most armies after all tiles have been placed. Each turn you received a randomly numbered tile (value between 1 and 20 armies) to place on any vacant board space. If this tile is adjacent to any ally tiles, it will strengthen each tile's defenses +1 (up to a max value of 20). If it is adjacent to any enemy tiles, it will take control over them if its number is higher than the number on the enemy tile. Thoughts on strategy: Here are some initial thoughts; setting the computer AI to Expert will probably teach a lot: minimizing your perimeter seems to be a good strategy, to prevent flips and minimize worst-case damage like in Go, leaving holes inside your formation is lethal, only more so with the hex grid because you can lose armies on up to 6 squares in one move low-numbered tiles are a liability, so place them away from your main territory, near the board edges and scattered. You can also use low-numbered tiles to plug holes in your formation, or make small gains along the perimeter which the opponent will not tend to bother attacking. a triangle formation of three pieces is strong since they mutually reinforce, and also reduce the perimeter Each tile can be flipped at most 6 times, i.e. when its neighbor tiles are occupied. Control of a formation can flow back and forth. Sometimes you lose part of a formation and plug any holes to render that part of the board 'dead' and lock in your territory/ prevent further losses. Low-numbered tiles are obvious-but-low-valued liabilities, but high-numbered tiles can be bigger liabilities if they get flipped (which is harder). One lucky play with a 20-army tile can cause a swing of 200 (from +100 to -100 armies). So tile placement will have both offensive and defensive considerations. Comment 1,2,4 seem to resemble a minimax strategy where we minimize the maximum expected possible loss (modified by some probabilistic consideration of the value ß the opponent can get from 1..20 i.e. a structure which can only be flipped by a ß=20 tile is 'nearly impregnable'.) I'm not clear what the implications of comments 3,5,6 are for optimal strategy. Interested in comments from Go, Chess or Othello players. (The sequel ProximityHD for XBox Live, allows 4-player -cooperative or -competitive local multiplayer increases the branching factor since you now have 5 tiles in your hand at any given time, of which you can only play one. Reinforcement of ally tiles is increased to +2 per ally.)

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  • Find optimal/good-enough strategy and AI for the game 'Proximity'?

    - by smci
    'Proximity' is a strategy game of territorial domination similar to Othello, Go and Risk. Two players, uses a 10x12 hex grid. Game invented by Brian Cable in 2007. Seems to be a worthy game for discussing a) optimal algorithm then b) how to build an AI. Strategies are going to be probabilistic or heuristic-based, due to the randomness factor, and the insane branching factor (20^120). So it will be kind of hard to compare objectively. A compute time limit of 5s per turn seems reasonable. Game: Flash version here and many copies elsewhere on the web Rules: here Object: to have control of the most armies after all tiles have been placed. Each turn you received a randomly numbered tile (value between 1 and 20 armies) to place on any vacant board space. If this tile is adjacent to any ally tiles, it will strengthen each tile's defenses +1 (up to a max value of 20). If it is adjacent to any enemy tiles, it will take control over them if its number is higher than the number on the enemy tile. Thoughts on strategy: Here are some initial thoughts; setting the computer AI to Expert will probably teach a lot: minimizing your perimeter seems to be a good strategy, to prevent flips and minimize worst-case damage like in Go, leaving holes inside your formation is lethal, only more so with the hex grid because you can lose armies on up to 6 squares in one move low-numbered tiles are a liability, so place them away from your main territory, near the board edges and scattered. You can also use low-numbered tiles to plug holes in your formation, or make small gains along the perimeter which the opponent will not tend to bother attacking. a triangle formation of three pieces is strong since they mutually reinforce, and also reduce the perimeter Each tile can be flipped at most 6 times, i.e. when its neighbor tiles are occupied. Control of a formation can flow back and forth. Sometimes you lose part of a formation and plug any holes to render that part of the board 'dead' and lock in your territory/ prevent further losses. Low-numbered tiles are obvious-but-low-valued liabilities, but high-numbered tiles can be bigger liabilities if they get flipped (which is harder). One lucky play with a 20-army tile can cause a swing of 200 (from +100 to -100 armies). So tile placement will have both offensive and defensive considerations. Comment 1,2,4 seem to resemble a minimax strategy where we minimize the maximum expected possible loss (modified by some probabilistic consideration of the value ß the opponent can get from 1..20 i.e. a structure which can only be flipped by a ß=20 tile is 'nearly impregnable'.) I'm not clear what the implications of comments 3,5,6 are for optimal strategy. Interested in comments from Go, Chess or Othello players. (The sequel ProximityHD for XBox Live, allows 4-player -cooperative or -competitive local multiplayer increases the branching factor since you now have 5 tiles in your hand at any given time, of which you can only play one. Reinforcement of ally tiles is increased to +2 per ally.)

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  • CSG operations on implicit surfaces with marching cubes

    - by Mads Elvheim
    I render isosurfaces with marching cubes, (or perhaps marching squares as this is 2D) and I want to do set operations like set difference, intersection and union. I thought this was easy to implement, by simply choosing between two vertex scalars from two different implicit surfaces, but it is not. For my initial testing, I tried with two spheres, and the set operation difference. i.e A - B. One sphere is moving and the other one is stationary. Here's the approach I tried when picking vertex scalars and when classifying corner vertices as inside or outside. The code is written in C++. OpenGL is used for rendering, but that's not important. Normal rendering without any CSG operations does give the expected result. void march(const vec2& cmin, //min x and y for the grid cell const vec2& cmax, //max x and y for the grid cell std::vector<vec2>& tri, float iso, float (*cmp1)(const vec2&), //distance from stationary sphere float (*cmp2)(const vec2&) //distance from moving sphere ) { unsigned int squareindex = 0; float scalar[4]; vec2 verts[8]; /* initial setup of the grid cell */ verts[0] = vec2(cmax.x, cmax.y); verts[2] = vec2(cmin.x, cmax.y); verts[4] = vec2(cmin.x, cmin.y); verts[6] = vec2(cmax.x, cmin.y); float s1,s2; /********************************** ********For-loop of interest****** *******Set difference between **** *******two implicit surfaces****** **********************************/ for(int i=0,j=0; i<4; ++i, j+=2){ s1 = cmp1(verts[j]); s2 = cmp2(verts[j]); if((s1 < iso)){ //if inside sphere1 if((s2 < iso)){ //if inside sphere2 scalar[i] = s2; //then set the scalar to the moving sphere } else { scalar[i] = s1; //only inside sphere1 squareindex |= (1<<i); //mark as inside } } else { scalar[i] = s1; //inside neither sphere } } if(squareindex == 0) return; /* Usual interpolation between edge points to compute the new intersection points */ verts[1] = mix(iso, verts[0], verts[2], scalar[0], scalar[1]); verts[3] = mix(iso, verts[2], verts[4], scalar[1], scalar[2]); verts[5] = mix(iso, verts[4], verts[6], scalar[2], scalar[3]); verts[7] = mix(iso, verts[6], verts[0], scalar[3], scalar[0]); for(int i=0; i<10; ++i){ //10 = maxmimum 3 triangles, + one end token int index = triTable[squareindex][i]; //look up our indices for triangulation if(index == -1) break; tri.push_back(verts[index]); } } This gives me weird jaggies: It looks like the CSG operation is done without interpolation. It just "discards" the whole triangle. Do I need to interpolate in some other way, or combine the vertex scalar values? I'd love some help with this. A full testcase can be downloaded HERE

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  • [C#][XNA] Draw() 20,000 32 by 32 Textures or 1 Large Texture 20,000 Times

    - by Rudi
    The title may be confusing - sorry about that, it's a poor summary. Here's my dilemma. I'm programming in C# using the .NET Framework 4, and aiming to make a tile-based game with XNA. I have one large texture (256 pixels by 4096 pixels). Remember this is a tile-based game, so this texture is so massive only because it contains many tiles, which are each 32 pixels by 32 pixels. I think the experts will definitely know what a tile-based game is like. The orientation is orthogonal (like a chess board), not isometric. In the Game.Draw() method, I have two choices, one of which will be incredibly more efficient than the other. Choice/Method #1: Semi-Pseudocode: public void Draw() { // map tiles are drawn left-to-right, top-to-bottom for (int x = 0; x < mapWidth; x++) { for (int y = 0; y < mapHeight; y++) { SpriteBatch.Draw( MyLargeTexture, // One large 256 x 4096 texture new Rectangle(x, y, 32, 32), // Destination rectangle - ignore this, its ok new Rectangle(x, y, 32, 32), // Notice the source rectangle 'cuts out' 32 by 32 squares from the texture corresponding to the loop Color.White); // No tint - ignore this, its ok } } } Caption: So, effectively, the first method is referencing one large texture many many times, each time using a small rectangle of this large texture to draw the appropriate tile image. Choice/Method #2: Semi-Pseudocode: public void Draw() { // map tiles are drawn left-to-right, top-to-bottom for (int x = 0; x < mapWidth; x++) { for (int y = 0; y < mapHeight; y++) { Texture2D tileTexture = map.GetTileTexture(x, y); // Getting a small 32 by 32 texture (different each iteration of the loop) SpriteBatch.Draw( tileTexture, new Rectangle(x, y, 32, 32), // Destination rectangle - ignore this, its ok new Rectangle(0, 0, tileTexture.Width, tileTexture.Height), // Notice the source rectangle uses the entire texture, because the entire texture IS 32 by 32 Color.White); // No tint - ignore this, its ok } } } Caption: So, effectively, the second method is drawing many small textures many times. The Question: Which method and why? Personally, I would think it would be incredibly more efficient to use the first method. If you think about what that means for the tile array in a map (think of a large map with 2000 by 2000 tiles, let's say), each Tile object would only have to contain 2 integers, for the X and Y positions of the source rectangle in the one large texture - 8 bytes. If you use method #2, however, each Tile object in the tile array of the map would have to store a 32by32 Texture - an image - which has to allocate memory for the R G B A pixels 32 by 32 times - is that 4096 bytes per tile then? So, which method and why? First priority is speed, then memory-load, then efficiency or whatever you experts believe.

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