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• PHP script stops running arbitrarily with no errors.

  - by RobHardgood

  I was working on a fairly long script that seemed to stop running after about 20 minutes. After days of trying to figure out why, I decided to make a very simple script to see how long it would run without any complex code to confuse me. I found that the same thing was happening with this simple infinite loop. At some point between 15 and 25 minutes of running, it simply stopped. There is no error output at all. The bottom of the browser simply says "Done" and nothing else is processed. I've been over every single possible thing I could think of... set_time_limit, session.gc_maxlifetime in the php.ini as well as memory_limit and max_execution_time. The point that the script is stopped is never consistent. Sometimes it will stop at 15 minutes, sometimes 22 minutes, sometimes 17... But it's always long enough to be a PITA to test. Please, any help would be greatly appreciated. It is hosted on a 1and1 server. I contacted them and they couldn't help me... but I have a feeling they just didn't know enough.

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• Finding cause of memory leaks in large PHP stacks

  - by Mike B

  I have CLI script that runs over several thousand iterations between runs and it appears to have a memory leak. I'm using a tweaked version of Zend Framework with Smarty for view templating and each iteration uses several MB worth of code. The first run immediately uses nearly 8MB of memory (which is fine) but every following run adds about 80kb. My main loop looks like this (very simplified) $users = UsersModel::getUsers(); foreach($users as $user) { $obj = new doSomethingAwesome(); $obj->run($user); $obj = null; unset($obj); } The point is that everything in scope should be unset and the memory freed. My understanding is that PHP runs through its garbage collection process at it's own desire but it does so at the end of functions/methods/scripts. So something must be leaking memory inside doSomethingAwesome() but as I said it is a huge stack of code. Ideally, I would love to find some sort of tool that displayed all my variables no matter the scope at some point during execution. Some sort of symbol-table viewer for php. Does anything like that or any other tools that could help nail down memory leaks in php exist?

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• Python: Does one of these examples waste more memory?

  - by orokusaki

  In a Django view function which uses manual transaction committing, I have: context = RequestContext(request, data) transaction.commit() return render_to_response('basic.html', data, context) # Returns a Django ``HttpResponse`` object which is similar to a dictionary. I think it is a better idea to do this: context = RequestContext(request, data) response = render_to_response('basic.html', data, context) transaction.commit() return response If the page isn't rendered correctly in the second version, the transaction is rolled back. This seems like the logical way of doing it albeit there won't likely be many exceptions at that point in the function when the application is in production. But... I fear that this might cost more and this will be replete through a number of functions since the application is heavy with custom transaction handling, so now is the time to figure out. If the HttpResponse instance is in memory already (at the point of render_to_response()), then what does another reference cost? When the function ends, doesn't the reference (response variable) go away so that when Django is done converting the HttpResponse into a string for output Python can immediately garbage collect it? Is there any reason I would want to use the first version (other than "It's 1 less line of code.")?

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• caching previous return values of procedures in scheme

  - by Brock

  In Chapter 16 of "The Seasoned Schemer", the authors define a recursive procedure "depth", which returns 'pizza nested in n lists, e.g (depth 3) is (((pizza))). They then improve it as "depthM", which caches its return values using set! in the lists Ns and Rs, which together form a lookup-table, so you don't have to recurse all the way down if you reach a return value you've seen before. E.g. If I've already computed (depthM 8), when I later compute (depthM 9), I just lookup the return value of (depthM 8) and cons it onto null, instead of recursing all the way down to (depthM 0). But then they move the Ns and Rs inside the procedure, and initialize them to null with "let". Why doesn't this completely defeat the point of caching the return values? From a bit of experimentation, it appears that the Ns and Rs are being reinitialized on every call to "depthM". Am I misunderstanding their point? I guess my question is really this: Is there a way in Scheme to have lexically-scoped variables preserve their values in between calls to a procedure, like you can do in Perl 5.10 with "state" variables?

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• Objective-C properties are not being recognized in header file?

  - by Greg

  Hey folks, I wonder if I'm doing something completely stupid here... I'm clearly missing something. I've gotten used to the pattern of defining properties of a custom class, however I seem to be hitting a point where extended classes do not recognize new properties. Case of point, here's my header file: import import "MyTableViewController.h" @interface MyRootController : MyTableViewController { NSMutableArray *sectionList; } @property (nonatomic, retain) NSMutableArray *sectionList; @end Now, for some reason that "sectionList" property is not turning green within my interface file (ie: it's not being recognized as custom property it seems). As a result, I'm getting all kinds of errors down in my implementation. The first is right at the top of my implementation where I try to synthesize the property: import "MyRootController.h" @implementation MyRootController @synthesize sectionList; That synthesize line throws the error "No declaration of property 'sectionList' found in the interface". So, this is really confusing. I'm clearly doing something wrong, although I can't put my finger on what. One thought: I am extending another custom class of my own. Do I need to specify some kind of super-class declaration to keep the architecture from getting sealed one level up? Thanks!

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• Android SDK not recognizing debug-able device.

  - by kal.zekdor

  I'm new to Android development, and am attempting to run a test application on my actual device. I followed the instructions at http://developer.android.com/guide/developing/device.html (and related links), but the Android Debug Bridge (adb) doesn't recognize my connected device. Some quick background info, I'm running WinXP, developing with Eclipse, with a Motorola Droid running Android 2.1 as my physical device. An overview of the steps I've taken: Installed the Android SDK, downloading all necessary packages. Enabled USB Debugging on my device. Connected Device via USB, installing the driver from the SDK folder. I'll stop here (though I continued to setup my application to be debug-able in Eclipse), because I at this point I noticed a problem. Running "sdk\tools\adb devices" at this point (at least, by my understanding), should list my device as connected. However, running this yields only: List of devices attached My device recognizes that it's connected to a computer in debug mode, and my computer recognizes the device. However, I can't seem to get the sdk to recognize it. I'll leave out the steps I used to setup Eclipse for debugging on a device, as it doesn't seem relevant to the problem. I'll include them if requested. If anyone has any ideas, I'd greatly appreciate some assistance. Thanks in advance for your time.

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• ExecutorSerrvice memory leak on exception

  - by TofuBeer

  I am having a hard time tracking this down since the profiler keeps crashing (hotspot error). Before I go too deep into figuring it out I'd like to know if I really have a problem or not :-) I have a few thread pools created via: Executors.newFixedThreadPool(10); The threads connect to different web sites and, on occasion, I get connection refused and wind up throwing an exception. When I later on call Future.get() to get the result it will then catch the ExecutionException that wraps the exception that was thrown when the connection could not be made. The program uses a fairly constant amount of memory up until the point in time that the exceptions get thrown (they tend to happen in batches when a particular site is overloaded). After that point the memory again remains constant but at a higher level. So my question is along the lines of is the memory behaviour (reported by "top" on Unix) expected because the exceptions just triggered something or do I probably have an actual leak that I'll need to track down? Additionally when Future.get() throws an exception is there anything else I need to do besides catch the exception (such as call Future.cancel() on it)?

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• Tagging in Subversion - how do I make the decision about continuing to work on my trunk vs. the new

  - by Howiecamp

  I'm running Tortoise SVN to manage a project. Obviously the principles around tagging apply to any implementation of SVN but in this question I'll be referring to some TortoiseSVN-specific dialog boxes and messages. My working directory and the subversion repository structure both have a Source root directory and the Trunk, Tags and Branches directories underneath. (I couldn't figure out how to do a multilevel indented hierarchy in markdown without using bullets, so if someone could edit and fix this I'd appreciate it.) I'm working out of the Trunk directory in my working copy and it's pointing at the Trunk directory in the repo. I want to apply a Tag "Release1" so I click the "Branch/tag..." menu option and set the repo path as my [repo_path/bla/Source/Tags/Release1" tag. This dialog box gives me the option to "Switch my working copy to new branch/tag". I understand that if this option is left unchecked, the new "Release1" branch under /Tags" will be created but my working copy will remain on the previous "Trunk" path. If I do check this option (or use the Switch command) I understand that my working copy will switch to the new "Release1" branch under "/Tags". Where I'm missing a concept is how to make this decision. It doesn't seem like I want to switch my working directory to the recently created tag since by definition (?) I want that tag to be a snapshot of my code as of a point in time. If I don't switch the working directory, I'll continue working off Trunk and when I'm ready to take another snapshot I'll make another tag. And so on... Am I understanding this right or am I stating something incorrectly in the previous paragraph (e.g. the statement about not wanting to switch to the tag since the tag should represent a point in time snapshot) or otherwise missing something regarding how to make this decision?

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• PHP OOP: Avoid Singleton/Static Methods in Domain Model Pattern

  - by sunwukung

  I understand the importance of Dependency Injection and its role in Unit testing, which is why the following issue is giving me pause: One area where I struggle not to use the Singleton is the Identity Map/Unit of Work pattern (Which keeps tabs on Domain Object state). //Not actual code, but it should demonstrate the point class Monitor{//singleton construction omitted for brevity static $members = array();//keeps record of all objects static $dirty = array();//keeps record of all modified objects static $clean = array();//keeps record of all clean objects } class Mapper{//queries database, maps values to object fields public function find($id){ if(isset(Monitor::members[$id]){ return Monitor::members[$id]; } $values = $this->selectStmt($id); //field mapping process omitted for brevity $Object = new Object($values); Monitor::new[$id]=$Object return $Object; } $User = $UserMapper->find(1);//domain object is registered in Id Map $User->changePropertyX();//object is marked "dirty" in UoW // at this point, I can save by passing the Domain Object back to the Mapper $UserMapper->save($User);//object is marked clean in UoW //but a nicer API would be something like this $User->save(); //but if I want to do this - it has to make a call to the mapper/db somehow $User->getBlogPosts(); //or else have to generate specific collection/object graphing methods in the mapper $UserPosts = $UserMapper->getBlogPosts(); $User->setPosts($UserPosts); Any advice on how you might handle this situation? I would be loathe to pass/generate instances of the mapper/database access into the Domain Object itself to satisfy DI - At the same time, avoiding that results in lots of calls within the Domain Object to external static methods. Although I guess if I want "save" to be part of its behaviour then a facility to do so is required in its construction. Perhaps it's a problem with responsibility, the Domain Object shouldn't be burdened with saving. It's just quite a neat feature from the Active Record pattern - it would be nice to implement it in some way.

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• How to calculate the normal of points on a 3D cubic Bézier curve given normals for its start and end points?

  - by Robert

  I'm trying to render a "3D ribbon" using a single 3D cubic Bézier curve to describe it (the width of the ribbon is some constant). The first and last control points have a normal vector associated with them (which are always perpendicular to the tangents at those points, and describe the surface normal of the ribbon at those points), and I'm trying to smoothly interpolate the normal vector over the course of the curve. For example, given a curve which forms the letter 'C', with the first and last control points both having surface normals pointing upwards, the ribbon should start flat, parallel to the ground, slowly turn, and then end flat again, facing the same way as the first control point. To do this "smoothly", it would have to face outwards half-way through the curve. At the moment (for this case), I've only been able to get all the surfaces facing upwards (and not outwards in the middle), which creates an ugly transition in the middle. It's quite hard to explain, I've attached some images below of this example with what it currently looks like (all surfaces facing upwards, sharp flip in the middle) and what it should look like (smooth transition, surfaces slowly rotate round). Silver faces represent the front, black faces the back. Incorrect, what it currently looks like: Correct, what it should look like: All I really need is to be able to calculate this "hybrid normal vector" for any point on the 3D cubic bézier curve, and I can generate the polygons no problem, but I can't work out how to get them to smoothly rotate round as depicted. Completely stuck as to how to proceed!

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• How to globalize ASP.NET MVC views (decimal separators in particular)?

  - by Pawel Krakowiak

  I'm working with the NerdDinner sample application and arrived at the section which deals with the Virtual Earth map. The application stores some values for the longitude and latitude. Unfortunately on my system floating point numbers are stored with a comma as the decimal separator, not a dot like in the US. So if I have a latitude of 47.64 it's retrieved and displayed as 47,64. Because that value is passed in a function call to the Virtual Earth API it fails at that point (e.g. JavaScript API expects 47.64, -122.13, but gets 47,64, -122,13). I need to make sure that the application always uses dots. In a WebForms app I would have a common class which overrides the System.Web.UI.Page.InitializeCulture() method and I would be inheriting my pages from that class. I am not sure about how to do the same with MVC. Do I need a customized ViewPage or something? Is there an easy way to solve this? Examples?

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• SQLAlchemy Custom Type Which Contains Multiple Columns

  - by Kekoa

  I would like to represent a datatype as a single column in my model, but really the data will be stored in multiple columns in the database. I cannot find any good resources on how to do this in SQLAlchemy. I would like my model to look like this(this is a simplified example using geometry instead of my real problem which is harder to explain): class 3DLine(DeclarativeBase): start_point = Column(my.custom.3DPoint) end_point = Column(my.custom.3DPoint) This way I could assign an object with the (x, y, z) components of the point at once without setting them individually. If I had to separate each component, this could get ugly, especially if each class has several of these composite objects. I would combine the values into one encoded field except that I need to query each value separately at times. I was able to find out how to make custom types using a single column in the documentation. But there's no indication that I can map a single type to multiple columns. I suppose I could accomplish this by using a separate table, and each column would be a foreign key, but in my case I don't think it makes sense to have a one to one mapping for each point to a separate table, and this still does not give the ability to set the related values all at once.

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• View results of affine transform

  - by stckjp

  I am trying to find out the reason why when I apply affine transformations on an image in OpenCV, the result of it is not visible in the preview window, but the entire window is black.How can I find workaround for this problem so that I can always view my transformed image (the result of the affine transform) in the window no matter the applied transformation? Update: I think that this happens because all the transformations are calculated with respect to the origin of the coordinate system (top left corner of the image). While for rotation I can specify the center of the rotation, and I am able to view the result, when I perform scaling I am not able to control where the transformed image goes. Is it possible to somehow move the coordinate system to make the image fit in the window? Update2: I have an image which contains only ROI at some position in it (the rest of the image is black), and I need to apply a set of affine transforms on it. To make things simpler and to see the effect of each individual transform, I applied each transform one by one. What I noticed is that, whenever I move (translate) the image such that the center of the ROI is in the center of the coordinate system (top left corner of the view window), all the affine transforms perform correctly without moving. However, by translating the center of ROI at the center of the coordinate system, the upper and the left part of the ROI remain cut out of the current view window. If I move ROI's central point to another point in the view window (for example the window center), an affine transform of type: A=[a 0 0; 0 b 0] (A is 2x3 matrix, parameter of the warpAffine function) moves the image (ROI), outside of the view window (which doesn't happen if the ROI's center is in the top-left corner). How can I modify the affine transform so the image doesn't move out of its place (behaves the same way as when the ROI center is in the center of the coordinate system)?

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• What algorithm can I use to determine points within a semi-circle?

  - by khayman218

  I have a list of two-dimensional points and I want to obtain which of them fall within a semi-circle. Originally, the target shape was a rectangle aligned with the x and y axis. So the current algorithm sorts the pairs by their X coord and binary searches to the first one that could fall within the rectangle. Then it iterates over each point sequentially. It stops when it hits one that is beyond both the X and Y upper-bound of the target rectangle. This does not work for a semi-circle as you cannot determine an effective upper/lower x and y bounds for it. The semi-circle can have any orientation. Worst case, I will find the least value of a dimension (say x) in the semi-circle, binary search to the first point which is beyond it and then sequentially test the points until I get beyond the upper bound of that dimension. Basically testing an entire band's worth of points on the grid. The problem being this will end up checking many points which are not within the bounds.

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• Are there any downsides in using C++ for network daemons?

  - by badcat

  Hey guys! I've been writing a number of network daemons in different languages over the past years, and now I'm about to start a new project which requires a new custom implementation of a properitary network protocol. The said protocol is pretty simple - some basic JSON formatted messages which are transmitted in some basic frame wrapping to have clients know that a message arrived completely and is ready to be parsed. The daemon will need to handle a number of connections (about 200 at the same time) and do some management of them and pass messages along, like in a chat room. In the past I've been using mostly C++ to write my daemons. Often with the Qt4 framework (the network parts, not the GUI parts!), because that's what I also used for the rest of the projects and it was simple to do and very portable. This usually worked just fine, and I didn't have much trouble. Being a Linux administrator for a good while now, I noticed that most of the network daemons in the wild are written in plain C (of course some are written in other languages, too, but I get the feeling that 80% of the daemons are written in plain C). Now I wonder why that is. Is this due to a pure historic UNIX background (like KISS) or for plain portability or reduction of bloat? What are the reasons to not use C++ or any "higher level" languages for things like daemons? Thanks in advance! Update 1: For me using C++ usually is more convenient because of the fact that I have objects which have getter and setter methods and such. Plain C's "context" objects can be a real pain at some point - especially when you are used to object oriented programming. Yes, I'm aware that C++ is a superset of C, and that C code is basically C++. But that's not the point. ;)

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• Big-O for calculating all routes from GPS data

  - by HH

  A non-critical GPS module use lists because it needs to be modifiable, new routes added, new distances calculated, continuos comparisons. Well so I thought but my team member wrote something I am very hard to get into. His pseudo code int k =0; a[][] <- create mapModuleNearbyDotList -array //CPU O(n) for(j = 1 to n) // O(nlog(m)) for(i =1 to n) for(k = 1 to n) if(dot is nearby) adj[i][j]=min(adj[i][j], adj[i][k] + adj[k][j]); His ideas transformations of lists to tables His worst case time complexity is O(n^3), where n is number of elements in his so-called table. Exception to the last point with Finite structure: O(mlog(n)) where n is number of vertices and m is the amount of neighbour vertices. Questions about his ideas why to waste resources to transform constantly-modified lists to table? Fast? only point where I to some extent agree but cannot understand the same upper limits n for each for-loops -- perhaps he supposed it circular why does the code take O(mlog(n)) to proceed in time as finite structure? The term finite may be wrong, explicit?

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• Sizing issues while adding a .Net UserControl to a TabPage

  - by TJ_Fischer

  I have a complex Windows Forms GUI program that has a lot of automated control generation and manipulation. One thing that I need to be able to do is add a custom UserControl to a newly instatiated TabPage. However, when my code does this I get automatic resizing events that cause the formatting to get ugly. Without detailing all of the different Containers that could possibly be involved, the basic issue is this: At a certain point in the code I create a new tab page: TabPage tempTabPage = new TabPage("A New Tab Page"); Then I set it to a certain size that I want it to maintain: tempTabPage.Width = 1008; tempTabPage.Height = 621; Then I add it to a TabControl: tabControl.TabPages.Add(tempTabPage); Then I create a user control that I want to appear in the newly added TabPage: CustomView customView = new CustomView("A new custom control"); Here is where the problem comes in. At this point both the tempTabPage and the customView are the same size with no padding or margin and they are the size I want them to be. I now try to add this new custom UserControl to the tab page like this: tempTabPage.Controls.Add(customView); When making this call the customView and it's children controls get resized to be larger and so parts of the customView are hidden. Can anyone give me any direction on what to look for or what could be causing this kind of issue? Thanks ahead of time.

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• How do you use stl's functions like for_each?

  - by thomas-gies

  I started using stl containers because they came in very handy when I needed functionality of a list, set and map and had nothing else available in my programming environment. I did not care much about the ideas behind it. STL documentations were only interesting up to the point where it came to functions, etc. Then I skipped reading and just used the containers. But yesterday, still being relaxed from my holidays, I just gave it a try and wanted to go a bit more the stl way. So I used the transform function (can I have a little bit of applause for me, thank you). From an academic point of view it really looked interesting and it worked. But the thing that boroughs me is that if you intensify the use of those functions, you need 10ks of helper classes for mostly everything you want to do in your code. The hole logic of the program is sliced in tiny pieces. This slicing is not the result of god coding habits. It's just a technical need. Something, that makes my life probably harder not easier. And I learned the hard way, that you should always choose the simplest approach that solves the problem at hand. And I can't see what, for example, the for_each function is doing for me that justifies the use of a helper class over several simple lines of code that sit inside a normal loop so that everybody can see what is going on. I would like to know, what you are thinking about my concerns? Did you see it like I do when you started working this way and have changed your mind when you got used to it? Are there benefits that I overlooked? Or do you just ignore this stuff as I did (and will go an doing it, probably). Thanks. PS: I know that there is a real for_each loop in boost. But I ignore it here since it is just a convenient way for my usual loops with iterators I guess.

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• Resource placement (optimal strategy)

  - by blackened

  I know that this is not exactly the right place to ask this question, but maybe a wise guy comes across and has the solution. I'm trying to write a computer game and I need an algorithm to solve this question: The game is played between 2 players. Each side has 1.000 dollars. There are three "boxes" and each player writes down the amount of money he is going to place into those boxes. Then these amounts are compared. Whoever placed more money in a box scores 1 point (if draw half point each). Whoever scores more points wins his opponents 1.000 dollars. Example game: Player A: [500, 500, 0] Player B: [333, 333, 334] Player A wins because he won Box A and Box B (but lost Box C). Question: What is the optimal strategy to place the money? I have more questions to ask (algorithm related, not math related) but I need to know the answer to this one first. Update (1): After some more research I've learned that these type of problems/games are called Colonel Blotto Games. I did my best and found few (highly technical) documents on the subject. Cutting it short, the problem I have (as described above) is called simple Blotto Game (only three battlefields with symmetric resources). The difficult ones are the ones with, say, 10+ battle fields with non-symmetric resources. All the documents I've read say that the simple Blotto game is easy to solve. The thing is, none of them actually say what that "easy" solution is.

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• Help! Getting an error copying the data from one column to the same column in a similar recordset..

  - by Mike D

  I have a routine which reads one recordset, and adds/updates rows in a similar recordset. The routine starts off by copying the columns to a new recordset: Here's the code for creating the new recordset.. For X = 1 To aRS.Fields.Count mRS.Fields.Append aRS.Fields(X - 1).Name, aRS.Fields(X - 1).Type, aRS.Fields(X - _ 1).DefinedSize, aRS.Fields(X - 1).Attributes Next X Pretty straight forward. Notice the copying of the name, Type, DefinedSize & Attributes... Further down in the code, (and there's nothing that modifies any of the columns between.. ) I'm copying the values of a row to a row in the new recordset as such: For C = 1 To aRS.Fields.Count mRS.Fields(C - 1) = aRS.Fields(C - 1) Next C When it gets to the last column which is a numeric, it craps with the "Mutliple-Step Operation Generated an error" message. I know that MS says this is an error generated by the provider, which in this case is ADO 2.8. There is no open connect to the DB at this point in time either. I'm pulling what little hair I have left over this one... (and I don't really care at this point that the column index is 'X' in one loop & 'C' in the other... I'll change it later when I get the real problem fixed...)

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• Calculating collision for a moving circle, without overlapping the boundaries

  - by Robert Vella

  Let's say I have circle bouncing around inside a rectangular area. At some point this circle will collide with one of the surfaces of the rectangle and reflect back. The usual way I'd do this would be to let the circle overlap that boundary and then reflect the velocity vector. The fact that the circle actually overlaps the boundary isn't usually a problem, nor really noticeable at low velocity. At high velocity it becomes quite clear that the circle is doing something it shouldn't. What I'd like to do is to programmatically take reflection into account and place the circle at it's proper position before displaying it on the screen. This means that I have to calculate the point where it hits the boundary between it's current position and it's future position -- rather than calculating it's new position and then checking if it has hit the boundary. This is a little bit more complicated than the usual circle/rectangle collision problem. I have a vague idea of how I should do it -- basically create a bounding rectangle between the current position and the new position, which brings up a slew of problems of it's own (Since the rectangle is rotated according to the direction of the circle's velocity). However, I'm thinking that this is a common problem, and that a common solution already exists. Is there a common solution to this kind of problem? Perhaps some basic theories which I should look into?

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• Move camera to fit 3D scene

  - by Burre

  Hi there. I'm looking for an algorithm to fit a bounding box inside a viewport (in my case a DirectX scene). I know about algorithms for centering a bounding sphere in a orthographic camera but would need the same for a bounding box and a perspective camera. I have most of the data: I have the up-vector for the camera I have the center point of the bounding box I have the look-at vector (direction and distance) from the camera point to the box center I have projected the points on a plane perpendicular to the camera and retrieved the coefficients describing how much the max/min X and Y coords are within or outside the viewing plane. Problems I have: Center of the bounding box isn't necessarily in the center of the viewport (that is, it's bounding rectangle after projection). Since the field of view "skew" the projection (see http://en.wikipedia.org/wiki/File:Perspective-foreshortening.svg) I cannot simply use the coefficients as a scale factor to move the camera because it will overshoot/undershoot the desired camera position How do I find the camera position so that it fills the viewport as pixel perfect as possible (exception being if the aspect ratio is far from 1.0, it only needs to fill one of the screen axis)? I've tried some other things: Using a bounding sphere and Tangent to find a scale factor to move the camera. This doesn't work well, because, it doesn't take into account the perspective projection, and secondly spheres are bad bounding volumes for my use because I have a lot of flat and long geometries. Iterating calls to the function to get a smaller and smaller error in the camera position. This has worked somewhat, but I can sometimes run into weird edge cases where the camera position overshoots too much and the error factor increases. Also, when doing this I didn't recenter the model based on the position of the bounding rectangle. I couldn't find a solid, robust way to do that reliably. Help please!

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• Approaches for animating a C# property over time?

  - by Mario Fritsch

  I'm currently trying to animate a bunch of public properties on certain objects. Usually they are of type float or vectors of floats (the type is known at compile-time). I want to be able to: assign a static value to them (MyObject.Duration = 10f;) or assign a random value to them by specifying a minimum and maximum value and optionally also a weight (MyObject.Duration = new RandomFloat(5f, 20f, 2f);) or "bind" this property to the property of another object (think of a child object binding some of its properties to its parent object, like its color or size or sth.) or assign sort of a keyframe animation to them, specifying a variable number of keyframes with timecode and the property's value at that specific point in time as well as information about how to interpolate between these frames The keyframes should be able to accept random values for each frame, both for the time and the property's value. What would be a practical approach for this kind of system? Currently I'm thinking about polymorphism: implement a base class or interface with a public Value-property and/or GetValue(float time)-method and then creating different sub classes like StaticValue, RandomValue, BindingValue and AnimatedValue implementing this base class or interface. Doesn't seem very elegant, though, and the initialization of even simple objects becomes a bit tedious. Another idea would be to implement these properties just as regular floats or vectors and create special "Modifier"-types binding to these properties. To retrieve the "real" value of the property, I'd first call any Modifier bound to the property, which would in turn update the actual object's property for me to retrieve later on. That would most likely mean using reflection at some point, which could be quite bad for performance as I'll probably have thousands of properties to update dozens of times per second. Any suggestions on this? Being a novice I'm (hopefully) missing some far more elegant and/or practical solution than I'm already playing around with :( Edit: Probably should have mentioned this earlier, but WPF isn't an option - it's not available on all targetted platforms, so I can't rely on it. I'm aware of its powerful databinding and animation capabilities, but I need to roll my own (or find some other lightweight alternative meeting my needs).

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• How to take html markup from a string and escape it to work within a script?

  - by zac

  I am using wordpress as a CMS and trying to allow user fields to be input to populate the info windows in a Google Map script. I am using this to select the id and pull in the content from a custom field : $post_id = 222; $my_post = get_post($post_id); $snip = get_post_meta($post_id, 'custom-field', true); $permalink = get_permalink( $post_id ); $pass_to = '<div class="content">'.$snip.'</div><div class="moreLink"><a href="'.$permalink.'">Find out more » </a></div></div>'; var point = new GLatLng('<?php echo $lat; $lat; ?>','<?php echo $long; $long; ?>'); var marker = createMarker(point,"<?php echo $mapTitle; $mapTitle; ?>", '<?php echo $pass_to; ?>') map.addOverlay(marker); It works fine unless there is any html in the custom-field which breaks the script. I looked at htmlspcialchar and htmlentities but rather than strip everything out I would like to have it escaped so it still works and the html is intact. Any suggestions? I am pretty new to PHP and would really appreciate any pointers.

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• Finding the width of a directed acyclic graph... with only the ability to find parents

  - by Platinum Azure

  Hi guys, I'm trying to find the width of a directed acyclic graph... as represented by an arbitrarily ordered list of nodes, without even an adjacency list. The graph/list is for a parallel GNU Make-like workflow manager that uses files as its criteria for execution order. Each node has a list of source files and target files. We have a hash table in place so that, given a file name, the node which produces it can be determined. In this way, we can figure out a node's parents by examining the nodes which generate each of its source files using this table. That is the ONLY ability I have at this point, without changing the code severely. The code has been in public use for a while, and the last thing we want to do is to change the structure significantly and have a bad release. And no, we don't have time to test rigorously (I am in an academic environment). Ideally we're hoping we can do this without doing anything more dangerous than adding fields to the node. I'll be posting a community-wiki answer outlining my current approach and its flaws. If anyone wants to edit that, or use it as a starting point, feel free. If there's anything I can do to clarify things, I can answer questions or post code if needed. Thanks! EDIT: For anyone who cares, this will be in C. Yes, I know my pseudocode is in some horribly botched Python look-alike. I'm sort of hoping the language doesn't really matter.

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