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  • how can I save/keep-in-sync an in-memory graph of objects with the database?

    - by Greg
    Question - What is a good best practice approach for how can I save/keep-in-sync an jn-memory graph of objects with the database? Background: That is say I have the classes Node and Relationship, and the application is building up a graph of related objects using these classes. There might be 1000 nodes with various relationships between them. The application needs to query the structure hence an in-memory approach is good for performance no doubt (e.g. traverse the graph from Node X to find the root parents) The graph does need to be persisted however into a database with tables NODES and RELATIONSHIPS. Therefore what is a good best practice approach for how can I save/keep-in-sync an jn-memory graph of objects with the database? Ideal requirements would include: build up changes in-memory and then 'save' afterwards (mandatory) when saving, apply updates to database in correct order to avoid hitting any database constraints (mandatory) keep persistence mechanism separate from model, for ease in changing persistence layer if needed, e.g. don't just wrap an ADO.net DataRow in the Node and Relationship classes (desirable) mechanism for doing optimistic locking (desirable) Or is the overhead of all this for a smallish application just not worth it and I should just hit the database each time for everything? (assuming the response times were acceptable) [would still like to avoid if not too much extra overhead to remain somewhat scalable re performance]

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  • Simple continuously running XMPP client in python

    - by tom
    I'm using python-xmpp to send jabber messages. Everything works fine except that every time I want to send messages (every 15 minutes) I need to reconnect to the jabber server, and in the meantime the sending client is offline and cannot receive messages. So I want to write a really simple, indefinitely running xmpp client, that is online the whole time and can send (and receive) messages when required. My trivial (non-working) approach: import time import xmpp class Jabber(object): def __init__(self): server = 'example.com' username = 'bot' passwd = 'password' self.client = xmpp.Client(server) self.client.connect(server=(server, 5222)) self.client.auth(username, passwd, 'bot') self.client.sendInitPresence() self.sleep() def sleep(self): self.awake = False delay = 1 while not self.awake: time.sleep(delay) def wake(self): self.awake = True def auth(self, jid): self.client.getRoster().Authorize(jid) self.sleep() def send(self, jid, msg): message = xmpp.Message(jid, msg) message.setAttr('type', 'chat') self.client.send(message) self.sleep() if __name__ == '__main__': j = Jabber() time.sleep(3) j.wake() j.send('[email protected]', 'hello world') time.sleep(30) The problem here seems to be that I cannot wake it up. My best guess is that I need some kind of concurrency. Is that true, and if so how would I best go about that? EDIT: After looking into all the options concerning concurrency, I decided to go with twisted and wokkel. If I could, I would delete this post.

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  • Rails form with a better URL

    - by Sam
    Wow, switching to REST is a different paradigm for sure and is mainly a headache right now. view <% form_tag (businesses_path, :method => "get") do %> <%= select_tag :business_category_id, options_for_select(@business_categories.collect {|bc| [bc.name, bc.id ]}.insert(0, ["All Containers", 0]), which_business_category(@business_category) ), { :onchange => "this.form.submit();"} %> <% end %> controller def index @business_categories = BusinessCategory.find(:all) if params[:business_category_id].to_i != 0 @business_category = BusinessCategory.find(params[:business_category_id]) @businesses = @business_category.businesses else @businesses = Business.all end respond_to do |format| format.html # index.html.erb format.xml { render :xml => @businesses } end end routes map.resources What I want to to is get a better URL than what this form is presenting which is the following: http://localhost:3000/businesses?business_category_id=1 Without REST I would have do something like http://localhost:3000/business/view/bbq bbq as permalink or I would have done http://localhost:300/business_categories/view/bbq and get the business that are associated with the category but I don't really know the best way of doing this. So the two questions are what is the best logic of finding a business by its categories using the latter form and number two how to get that in a pretty URL all through RESTful routes in Rails.

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  • Assemble an image browser side with JavaScript or Flash?

    - by Kris Walker
    Would it be possible to assemble an image on the browser by 'concatenating' other downloaded images together? The use case is this. The page will display 36 different tiles (small images). The user should be able to arrange those tiles into a 6 x 6 grid and save the resulting grid to disk as an image. The best solution would be to do it all in the browser without Flash. The next best solution would be to allow the user to create the grid in the browser with simple JavaScript drag and drop functionality and then send the coordinates to the server for image processing. The last solution would be to do it all in the browser with Flash. Is it even possible for Flash to create an image and then allow the user to save it from the browser? I am familiar with the Pixastic JavaScript library ( http://www.pixastic.com/ ), but it relies on getting image data to and from a canvas element which is not very well supported. What if I send the tile images to the browser as base64 encoded strings? Could I use JavaScript to create the 6 x 6 grid image? And if so, is there some way of allowing the user to get it onto disk without relying on the canvas element?

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  • Recommendations to handle development and deployment of php web apps using shared project code

    - by Exception e
    I am wondering what the best way (for a lone developer) is to develop a project that depends on code of other projects deploy the resulting project to the server I am planning to put my code in svn, and have shared code as a separate project. There are problems with svn:externals which I cannot fully estimate. I've read subversion:externals considered to be an anti-pattern, and How do you organize your version control repository, but there is one special thing with php-projects (and other interpreted source code): there is no final executable resulting from your libraries. External dependencies are thus always on raw source code. Ideally I really want to be able to develop simultaneously on one project and the projects it dependends on. Possible way: Check out a projects' dependency in a sub folder as a working copy of the trunk. Problems I foresee: When you want to deploy a project, you might want to freeze its dependencies, right? The dependency code should not end up as a duplicate in the projects repository, I think. *(update1: I additionally assume svn:ignore will pose problems if I cannot fall back on symlinks, see my comment) I am still looking for suggestions that do not require the use junction points. They are a sort of unsupported hack in winxp, which may break some programs* This leads me to the last part of the question (as one has influence on the other): how do you deploy apps whith such dependencies? I've looked into BuildOut for Python, but it seems to be tightly related to the python ecosystem (resolving and fetching python modules from the web etc). I am very eager to learn about your best practices.

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  • How to store some of the entity's values in another table using hibernate?

    - by nimcap
    Hi guys, is there a simple way to persist some of the fields in another class and table using hibernate. For example, I have a Person class with name, surname, email, address1, address2, city, country fields. I want my classes to be: public class Person { private String name; private String surname; private String email; private Address address; // .. } public class Address { private Person person; // to whom this belongs private String address1; private String address2; private String city; private Address country; // .. } and I want to store Address in another table. What is the best way to achieve this? Edit: I am using annotations. It does not have to be the way I described, I am looking for best practices. PS. If there is a way to make Address immutable (to use as a value object) that is even better, or maybe not because I thought everything from wrong perspective :)

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  • Building a ctypes-"based" C library with distutils

    - by Robie Basak
    Following this recommendation, I have written a native C extension library to optimise part of a Python module via ctypes. I chose ctypes over writing a CPython-native library because it was quicker and easier (just a few functions with all tight loops inside). I've now hit a snag. If I want my work to be easily installable using distutils using python setup.py install, then distutils needs to be able to build my shared library and install it (presumably into /usr/lib/myproject). However, this not a Python extension module, and so as far as I can tell, distutils cannot do this. I've found a few references to people other people with this problem: Someone on numpy-discussion with a hack back in 2006. Somebody asking on distutils-sig and not getting an answer. Somebody asking on the main python list and being pointed to the innards of an existing project. I am aware that I can do something native and not use distutils for the shared library, or indeed use my distribution's packaging system. My concern is that this will limit usability as not everyone will be able to install it easily. So my question is: what is the current best way of distributing a shared library with distutils that will be used by ctypes but otherwise is OS-native and not a Python extension module? Feel free to answer with one of the hacks linked to above if you can expand on it and justify why that is the best way. If there is nothing better, at least all the information will be in one place.

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  • Indentation control while developing a small python like language

    - by sap
    Hello, I'm developing a small python like language using flex, byacc (for lexical and parsing) and C++, but i have a few questions regarding scope control. just as python it uses white spaces (or tabs) for indentation, not only that but i want to implement index breaking like for instance if you type "break 2" inside a while loop that's inside another while loop it would not only break from the last one but from the first loop as well (hence the number 2 after break) and so on. example: while 1 while 1 break 2 'hello world'!! #will never reach this. "!!" outputs with a newline end 'hello world again'!! #also will never reach this. again "!!" used for cout end #after break 2 it would jump right here but since I don't have an "anti" tab character to check when a scope ends (like C for example i would just use the '}' char) i was wondering if this method would the the best: I would define a global variable, like "int tabIndex" on my yacc file that i would access in my lex file using extern. then every time i find a tab character on my lex file i would increment that variable by 1. when parsing on my yacc file if i find a "break" keyword i would decrement by the amount typed after it from the tabIndex variable, and when i reach and EOF after compiling and i get a tabIndex != 0 i would output compilation error. now the problem is, whats the best way to see if the indentation got reduced, should i read \b (backspace) chars from lex and then reduce the tabIndex variable (when the user doesn't use break)? another method to achieve this? also just another small question, i want every executable to have its starting point on the function called start() should i hardcode this onto my yacc file? sorry for the long question any help is greatly appreciated. also if someone can provide an yacc file for python would be nice as a guideline (tried looking on Google and had no luck). thanks in advance.

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  • Populating a foreign key table with variable user input

    - by Vincent
    I'm working on a website that will be based on user contributed data, submitted using a regular HTML form. To simplify my question, let's say that there will be two fields in the form: "User Name" and "Country" (this is just an example, not the actual site). There will be two tables in the database : "countries" and "users," with "users.country_id" being a foreign key to the "countries" table (one-to-many). The initial database will be empty. Users from all over the world will submit their names and the countries they live in and eventually the "countries" table will get filled out with all of the country names in the world. Since one country can have several alternative names, input like Chile, Chili, Chilli will generate 3 different records in the countries table, but in fact there is only one country. When I search for records from Chile, Chili and Chilli will not be included. So my question is - what would be the best way to deal with a situation like this, with conditions such that the initial database is empty, no other resources are available and everything is based on user input? How can I organize it in such way that Chile, Chili and Chilli would be treated as one country, with minimum manual interference. What are the best practices when it comes to normalizing user submitted data and is there a scientific term for this? I'm sure this is a common problem. Again, I used country names just to simplify my question, it can be anything that has possible different spellings.

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  • Debugging a Google Web Toolkit application that has an error when deployed on Google App Engine

    - by gerdemb
    I have a Google Web Toolkit application that I am deploying to Google App Engine. In the deployed application, I am getting a JavaScript error Uncaught TypeError: Cannot read property 'f' of null. This sounds like the JavaScript equivalent of a Java NullPointerException. The problem is that the GWT JavaScript is obfuscated, so it's impossible to debug in the browser and I can't reproduce the same problem in hosted mode where I could use the Java debugger. I think the reason I'm only seeing the error on the deployed application is that the database I'm using on the GAE server is triggering something differently than the test database I'm using during testing and development. So, any ideas about the best way to proceed? I've thought of the following things: Deploy a non-obsfucated version of my application. Despite a lot of Googling, I can't figure out how to do this using the automatic deploy script provided with the Google Eclipse Plugin. Does anyone know? Download and copy my GAE data to the local server Somehow point my development code to use the GAE server for data instead of the local test database. This seems like the best idea... Can anyone suggest how to proceed here? Finally, is there a way to catch these JavaScript errors on the production server and log them somewhere? Without logging, I won't have anyway to know if my users are having errors that don't occur on the server. The GWT.log() function is automatically stripped out of the production code...

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  • Customizing the TFS 2008 build sequence to avoid compilation and deploy SSRS

    - by Andrew
    I'm trying to create a CI process for SQL Server Reporting Services. I am fairly new to TFS but quite experienced with MSBuild. In the past I've used a combination of MSBuild with Team City so the whole build process is more or less custom. Here lies the start of my problems, as the solution I am deploying only contains Report Server projects (rds), no compilation is required. I thought that I would override the the first default task that TFS runs (EndToEndIteration) to override the default TFS build sequence and inject my own. The first snag that I have come across is that the build always fails, how can I set the status of the build to success? Currently the EndToEndIteration task is very light and only has a message. Is this the best method to create a custom build process in TFS where compilation is not required? Or should I use the default sequence and override one of the hook tasks mentioned in http://msdn.microsoft.com/en-us/library/aa337604%28VS.80%29.aspx (ie: AfterCompile) The core steps that I'd like to achieve are: Bundle the RDL and datasource files Connect to the host server to register/deploy the reports Re-apply any subscriptions that previously existed Run tests to verify the deployment succeeded and is returning results as expected I have found another article on Report services deployment: http://stackoverflow.com/questions/88710/reporting-services-deployment But it doesn't mention the best practice for customizing the standard build process. Any help would be appreciated.

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  • Good web hosting for ASP.NET MVC 1.0 app

    - by magellings
    I'm looking for hosting for an ASP.NET MVC 1.0 app. I've narrowed down with research to either asphostportal, asphostcentral, godaddy, or 1&1. I've ruled out crystaltech and softsyshosting due to price with better plans. Will be running a small e-commerce site written with ASP.NET MVC 1.0 and want to be sure it will work, as well as looking for cheapest price with best value in regards to disk space/bandwidth. And bandwidth is basically how much data can be sent from your site per month right? Any opinions appreciated as I'm finding this tough to narrow down. I know you can bin deploy MVC but heard full trust mode is required as well as some routing rules in IIS. 1&1 says they can't enable full trust. This is what I was looking at: name data(disk space/bandwidth) price MVCenabled crystal tech 500MB/50GB 7.95 + 7.95 setup 2000MB/200GB 16.95 softsyshosting 500MB/5GB 3.50 + 12/year domain 1000MB/10GB 5.84 3000MB/30GB 13.33 asphostportal 5GB/50GB 5.75 + 8.99/year yes 10GB/100GB 10.25 asphostcentral 2GB/15GB 4.99 yes 3GB/30GB 7.99/month domain free 5GB/40GB 11.99 godaddy 10GB/300GB 10.69 + 4.74/month 150GB/1500GB 6.99/month 1&1 10GB/unlimited 3.99 + free domain 150GB/unlimited 6.99 1&1 seems to be best value if MVC app will work. I'm a bit confused on bandwidth being unlimited. May seem like a good thing, but what if one website on the server is a resource hog because of this?

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  • Pattern for UI configuration

    - by TERACytE
    I have a Win32 C++ program that validates user input and updates the UI with status information and options. Currently it is written like this: void ShowError() { SetIcon(kError); SetMessageString("There was an error"); HideButton(kButton1); HideButton(kButton2); ShowButton(kButton3); } void ShowSuccess() { SetIcon(kError); std::String statusText (GetStatusText()); SetMessageString(statusText); HideButton(kButton1); HideButton(kButton2); ShowButton(kButton3); } // plus several more methods to update the UI using similar mechanisms I do not likes this because it duplicates code and causes me to update several methods if something changes in the UI. I am wondering if there is a design pattern or best practice to remove the duplication and make the functionality easier to understand and update. I could consolidate the code inside a config function and pass in flags to enable/disable UI items, but I am not convinced this is the best approach. Any suggestions and ideas?

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  • Can I use a static cache Helper method in a NET MVC controller?

    - by Euston
    I realise there have been a few posts regarding where to add a cache check/update and the separation of concerns between the controller, the model and the caching code. There are two great examples that I have tried to work with but being new to MVC I wonder which one is the cleanest and suits the MVC methodology the best? I know you need to take into account DI and unit testing. Example 1 (Helper method with delegate) ...in controller var myObject = CacheDataHelper.Get(thisID, () => WebServiceServiceWrapper.GetMyObjectBythisID(thisID)); Example 2 (check for cache in model class) in controller var myObject = WebServiceServiceWrapper.GetMyObjectBythisID(thisID)); then in model class.............. if (!CacheDataHelper.Get(cachekey, out myObject)) { //do some repository processing // Add obect to cache CacheDataHelper.Add(myObject, cachekey); } Both use a static cache helper class but the first example uses a method signature with a delegate method passed in that has the name of the repository method being called. If the data is not in cache the method is called and the cache helper class handles the adding or updating to the current cache. In the second example the cache check is part of the repository method with an extra line to call the cache helper add method to update the current cache. Due to my lack of experience and knowledge I am not sure which one is best suited to MVC. I like the idea of calling the cache helper with the delegate method name in order to remove any cache code in the repository but I am not sure if using the static method in the controller is ideal? The second example deals with the above but now there is no separation between the caching check and the repository lookup. Perhaps that is not a problem as you know it requires caching anyway?

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  • BeautifulSoup HTMLParseError. What's wrong with this?

    - by user1915496
    This is my code: from bs4 import BeautifulSoup as BS import urllib2 url = "http://services.runescape.com/m=news/recruit-a-friend-for-free-membership-and-xp" res = urllib2.urlopen(url) soup = BS(res.read()) other_content = soup.find_all('div',{'class':'Content'})[0] print other_content Yet an error comes up: /Library/Python/2.7/site-packages/bs4/builder/_htmlparser.py:149: RuntimeWarning: Python's built-in HTMLParser cannot parse the given document. This is not a bug in Beautiful Soup. The best solution is to install an external parser (lxml or html5lib), and use Beautiful Soup with that parser. See http://www.crummy.com/software/BeautifulSoup/bs4/doc/#installing-a-parser for help. "Python's built-in HTMLParser cannot parse the given document. This is not a bug in Beautiful Soup. The best solution is to install an external parser (lxml or html5lib), and use Beautiful Soup with that parser. See http://www.crummy.com/software/BeautifulSoup/bs4/doc/#installing-a-parser for help.")) Traceback (most recent call last): File "web.py", line 5, in <module> soup = BS(res.read()) File "/Library/Python/2.7/site-packages/bs4/__init__.py", line 172, in __init__ self._feed() File "/Library/Python/2.7/site-packages/bs4/__init__.py", line 185, in _feed self.builder.feed(self.markup) File "/Library/Python/2.7/site-packages/bs4/builder/_htmlparser.py", line 150, in feed raise e I've let two other people use this code, and it works for them perfectly fine. Why is it not working for me? I have bs4 installed...

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  • Algorithm for finding similar users through a join table

    - by Gdeglin
    I have an application where users can select a variety of interests from around 300 possible interests. Each selected interest is stored in a join table containing the columns user_id and interest_id. Typical users select around 50 interests out of the 300. I would like to build a system where users can find the top 20 users that have the most interests in common with them. Right now I am able to accomplish this using the following query: SELECT i2.user_id, count(i2.interest_id) AS count FROM interests_users as i1, interests_users as i2 WHERE i1.interest_id = i2.interest_id AND i1.user_id = 35 GROUP BY i2.user_id ORDER BY count DESC LIMIT 20; However, this query takes approximately 500 milliseconds to execute with 10,000 users and 500,000 rows in the join table. All indexes and database configuration settings have been tuned to the best of my ability. I have also tried avoiding the use of joins altogether using the following query: select user_id,count(interest_id) count from interests_users where interest_id in (13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,508) group by user_id order by count desc limit 20; But this one is even slower (~800 milliseconds). How could I best lower the time that I can gather this kind of data to below 100 milliseconds? I have considered putting this data into a graph database like Neo4j, but I am not sure if that is the easiest solution or if it would even be faster than what I am currently doing.

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  • Two questions on ensuring EndInvoke() gets called on a list of IAsyncResult objects

    - by RobV
    So this question is regarding the .Net IAsyncResult design pattern and the necessity of calling EndInvoke as covered in this question Background I have some code where I'm firing off potentially many asynchronous calls to a particular function and then waiting for all these calls to finish before using EndInvoke() to get back all the results. Question 1 I don't know whether any of the calls has encountered an exception until I call EndInvoke() and in the event that an exception occurs in one of the calls the entire method should fail and the exception gets wrapped into an API specific exception and thrown upwards. So my first question is what's the best way then to ensure that the remainder of the async calls get properly terminated? Is a finally block which calls EndInvoke() on the remainder of the unterminated calls (and ignores any further exceptions) the best way to do this? Question 2 Secondly when I first fire off all my asyc calls I then call WaitHandle.WaitAll() on the array of WaitHandle instances that I've got from my IAsyncResult instances. The method which is firing all these async calls has a timeout to adhere to so I provide this to the WaitAll() method. Then I test whether all the calls have completed, if not then the timeout must have been reached so the method should also fail and throw another API specific exception. So my second question is what should I do in this case? I need to call EndInvoke() to terminate all these async calls before I throw the error but at the same time I don't want the code to get stuck since EndInvoke() is blocking. In theory at least if the WaitAll() call times out then all the async calls should themselves have timed out and thrown exceptions (thus completing the call) since they are also governed by a timeout but this timeout is potentially different from the main timeout

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  • How can I tell when something outside my UITableViewCell has been touched?

    - by kk6yb
    Similar to this question I have a custom subclass of UITableViewCell that has a UITextField. Its working fine except the keyboard for doesn't go away when the user touches a different table view cell or something outside the table. I'm trying to figure out the best place to find out when something outside the cell is touched, then I could call resignFirstResponder on the text field. If the UITableViewCell could receive touch events for touches outside of its view then it could just resignFirstResponder itself but I don't see any way to get those events in the cell. The solution I'm considering is to add a touchesBegan:withEvent: method to the view controller. There I could send a resignFirstResponder to all tableview cells that are visible except the one that the touch was in (let it get the touch event and handle it itself). Maybe something like this pseudo code: - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { CGPoint touchPoint = // TBD - may need translate to cell's coordinates for (UITableViewCell* aCell in [theTableView visibleCells]) { if (![aCell pointInside:touchPoint withEvent:event]) { [aCell resignFirstResponder]; } } } I'm not sure if this is the best way to go about this. There doesn't seem to be any way for the tableviewcell itself to receive event notifications for events outside its view.

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  • Seperation of business logic

    - by bruno
    Dear all, When I was optimizing my architecture of our applications in our website, I came to a problem that I don't know the best solution for. Now at the moment we have a small dll based on this structure: Database <-> DAL <-> BLL the Dal uses Business Objects to pass to the BLL that will pass it to the applications that uses this dll. Only the BLL is public so any application that includes this dll, can see the bll. In the beginning, this was a good solution for our company. But when we are adding more and more applications on that Dll, the bigger the Bll is getting. Now we dont want that some applications can see Bll-logic from other applications. Now I don't know what the best solution is for that. The first thing I thought was, move and seperate the bll to other dll's which i can include in my application. But then must the Dal be public, so the other dll's can get the data... and that I seems like a good solution. My other soluition, is just to seperate the bll in different namespaces, and just include only the namespaces you need in the applications. But in this solution, you can get directly access to other bll's if you want. So i'm asking for your oppinions. Thx, Bruno

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  • Where in maven project's path should I put configuration files that are not considered resources

    - by Paralife
    I have a simple java maven project. One of my classes when executing needs to load an xml configuration file from the classpath. I dont want to package such xml file when producing the jar but I want to include a default xml file in a zip assemply under a conf subfolder and I also want this default xml to be available in the unit tests to test against it. As I see it there are 2 possible places of this default xml: src/main/resources/conf/default.xml src/main/conf/default.xml Both solutions demand special pom actions: In solution 1, I get the auto copy to target folder during build which means it is available in testing but I also get it in the produced jar which i dont want. In solution 2, I get the jar as I want it(free of the xml) but I manually have to copy the xml to the target folder to be available for testing. (I dont want to add src's subfolders in test classpath. I think it is bad practice). The question is what is the best solution of the two? If the correct is 2, what is the best way to copy it to target folder? Is there any other solution better and more common than those two? (I also read http://stackoverflow.com/questions/465001/where-should-i-put-application-configuration-files-for-a-maven-project but I would like to know the most "correct solution" from the "convention over configuration" point of view and this link provides some configuration type solutions but not any convention oriented. Maybe there isnt one but I ask anyway. Also the solutions provided include AntRun plugin and appAssembler plugin and I wonder if I could do it with out them.)

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  • Ogre material scripts; how do I give a technique multiple lod_indexes?

    - by BlueNovember
    I have an Ogre material script that defines 4 rendering techniques. 1 using GLSL shaders, then 3 others that just use textures of different resolutions. I want to use the GLSL shader unconditionally if the graphics card supports it, and the other 3 textures depending on camera distance. At the moment my script is; material foo { lod_distances 1600 2000 technique shaders { lod_index 0 lod_index 1 lod_index 2 //various passes here } technique high_res { lod_index 0 //various passes here } technique medium_res { lod_index 1 //various passes here } technique low_res { lod_index 2 //various passes here } Extra information The Ogre manual says; Increasing indexes denote lower levels of detail You can (and often will) assign more than one technique to the same LOD index, what this means is that OGRE will pick the best technique of the ones listed at the same LOD index. OGRE determines which one is 'best' by which one is listed first. Currently, on a machine supporting the GLSL version I am using, the script behaves as follows; Camera 2000 : Shader technique Camera 1600 <= 2000 : Medium Camera <= 1600 : High If I change the lod order in shader technique to { lod_index 2 lod_index 1 lod_index 0 } The behaviour becomes; Camera 2000 : Low Camera 1600 <= 2000 : Medium Camera <= 1600 : Shader implying only the latest lod_index is used. If I change it to lod_index 0 1 2 It shouts at me Compiler error: fewer parameters expected in foo.material(#): lod_index only supports 1 argument So how do I specify a technique to have 3 lod_indexes? Duplication works; technique shaders { lod_index 0 //various passes here } technique shaders1 { lod_index 1 //passes repeated here } technique shaders2 { lod_index 2 //passes repeated here } ...but it's ugly.

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  • Machine leaning algorithm for data classification.

    - by twk
    Hi all, I'm looking for some guidance about which techniques/algorithms I should research to solve the following problem. I've currently got an algorithm that clusters similar-sounding mp3s using acoustic fingerprinting. In each cluster, I have all the different metadata (song/artist/album) for each file. For that cluster, I'd like to pick the "best" song/artist/album metadata that matches an existing row in my database, or if there is no best match, decide to insert a new row. For a cluster, there is generally some correct metadata, but individual files have many types of problems: Artist/songs are completely misnamed, or just slightly mispelled the artist/song/album is missing, but the rest of the information is there the song is actually a live recording, but only some of the files in the cluster are labeled as such. there may be very little metadata, in some cases just the file name, which might be artist - song.mp3, or artist - album - song.mp3, or another variation A simple voting algorithm works fairly well, but I'd like to have something I can train on a large set of data that might pick up more nuances than what I've got right now. Any links to papers or similar projects would be greatly appreciated. Thanks!

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  • What image processing Library should I use

    - by Swippen
    I have been reading What is the best image manipulation library? And tried a few libraries and are now looking for inputs on what is the best for our need. I will start by describing our current setting and problems. We have a system that needs to resize and crop a large amount of images from big original images. We handle 50 000+ images every day on 2 powerfull servers. Today we use ImageGlue from WebSupergoo but we don't like it at all, it is slow and hangs the service now and then (Its in another unanswered stack overflow question). We have a threaded windows service that uses Microsoft ThreadPool to resize as much as possible on the 8 core machines. I have tried AForge and it went very well it was loads faster and never crashed or anything. But I had problems with quality on a few images. This due to what algorithms I used ofc so can be tweaked. But want to widen our eyes to see if thats the right way to go. so: It needs to be c# .net and run in a windows service. (Since we wont change the rest of the service only image handling) It needs to handle threaded environment well. We have a great need of it being fast since today its too slow. But we also want good quality and small filesize since the images are later displayed on webpage with loads of visitors and needs good quality. So we have a lot of demands on ability to get god quality at a fast pace, and also secondary keep filesizes lowered even if that can be adjusted with compression a bit. Any comments or suggestions on what library to use?

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  • how to clear XFixes regions

    - by ~buratinas
    Hi, I'm writing some low level code for X11 platform. To achieve best data copying performance I use XFixes/XDamage extensions. How can I clear the contents of XFixes region after one refresh cycle? Or do they clean themselves after I use XFixesSetPictureClipRegion? My code is something like that: Display xdpy; XShamPixmap pixmap_; XFixesRegion region_; damage_event_callback(damage_geometry_t geometry, XDamage damage,...) { unsigned curr_region = XFixesCreateRegion(xdpy, 0, 0); XDamageSubtract(xdpy, damage, None, curr_region); XFixesTranslateRegion( xdpy, curr_region, geometry.left(), geometry.top() ); XFixesUnionRegion (xdpy, region_, region_, curr_region); } process_damage_events(...) { XFixesSetPictureClipRegion( xdpy, pixmap_, 0, 0, region_); XCopyArea (xdpy, window_->id(), pixmap_, XDefaultGC(xdpy, XDefaultScreen(xdpy)), 0,0,width(),height(),0,0); /*Should clear region_ here */ ... } Currently I clear the region by deleting and recreating, but I guess it's not the best way to do that.

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  • Handling user interface in a multi-threaded application (or being forced to have a UI-only main thre

    - by Patrick
    In my application, I have a 'logging' window, which shows all the logging, warnings, errors of the application. Last year my application was still single-threaded so this worked [quite] good. Now I am introducing multithreading. I quickly noticed that it's not a good idea to update the logging window from different threads. Reading some articles on keeping the UI in the main thread, I made a communication buffer, in which the other threads are adding their logging messages, and from which the main thread takes the messages and shows them in the logging window (this is done in the message loop). Now, in a part of my application, the memory usage increases dramatically, because the separate threads are generating lots of logging messages, and the main thread cannot empty the communication buffer quickly enough. After the while the memory decreases again (if the other threads have finished their work and the main thread gradually empties the communication buffer). I solved this problem by having a maximum size on the communication buffer, but then I run into a problem in the following situation: the main thread has to perform a complex action the main thread takes some parts of the action and let's separate threads execute this while the seperate threads are executing their logic, the main thread processes the results from the other threads and continues with its work if the other threads are finished Problem is that in this situation, if the other threads perform logging, there is no UI-message loop, and so the communication buffer is filled, but not emptied. I see two solutions in solving this problem: require the main thread to do regular polling of the communication buffer only performing user interface logic in the main thread (no other logic) I think the second solution seems the best, but this may not that easy to introduce in a big application (in my case it performs mathematical simulations). Are there any other solutions or tips? Or is one of the two proposed the best, easiest, most-pragmatic solution? Thanks, Patrick

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