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• 2D water with dynamic waves

  - by user1103457

  New Super Mario Bros has really cool 2D water that I'd like to learn how to create. Here's a video showing it. When something hits the water, it creates a wave. There are also constant "background" waves. You can get a good look at the constant waves just after 00:50 when the camera isn't moving. I assume the splashes in NSMB work as in the first part of this tutorial. But in NSMB the water also has constant waves on the surface, and the splashes look very different. Another difference is that in the tutorial, if you create a splash, it first creates a deep "hole" in the water at the origin of the splash. In new super mario bros this hole is absent or much smaller. I am referring to the splashes that the player creates when jumping in and out of the water. How do they create the constant waves and the splashes? I am especially interested in the splashes, and how they work together with the constant waves. I am programming in XNA. I've tried this myself, but couldn't really get it all to work well together. Bonus questions: How do they create the light spots just under the surface of the waves and how do they texture the deeper parts of the water? This is the first time I try to create water like this. EDIT: I assume the constant waves are created using a sine function. The splashes are probably created in a way like in the tutorial. (But they are not the same, so I am still interested in how to make this kind of splashes) But I have a lot of trouble combining those things. I know I can use the sine function to set the height of a specific watercolumn but the splashes are using the speed, to determine the new height. I can't figure out how to combine those. Not that I am not asking how the developers of new super mario bros did this exactly. I am just interested in ways to recreate an effect like it. This week I have an examweek so I don't have time to work on the code. After this week I will spend a lot of time on it. But I am constantly thinking about it, so that's why I will be checking comments etc. I just won't be looking at the code since it might be too time-consuming.

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• How do I stop icons appearing on the desktop under conky?

  - by Seamus

  When I download something to my desktop, or insert a CD or flash drive, the icon appears on my desktop. When I have conky running, the icon sometimes appears in the top right corner, underneath conky; where I can't see it. How do I stop this happening? My .conkyrc is pasted below. I didn't write it all myself, so I'm not entirely sure what I need to change, or what parts are relevant for this particular question... # UBUNTU-CONKY # A comprehensive conky script, configured for use on # Ubuntu / Debian Gnome, without the need for any external scripts. # # Based on conky-jc and the default .conkyrc. # INCLUDES: # - tail of /var/log/messages # - netstat shows number of connections from your computer and application/PID making it. Kill spyware! # # -- Pengo # # Create own window instead of using desktop (required in nautilus) own_window yes own_window_type override own_window_transparent yes own_window_hints undecorated,below,sticky,skip_taskbar,skip_pager # Use double buffering (reduces flicker, may not work for everyone) double_buffer yes # fiddle with window use_spacer right # Use Xft? use_xft yes xftfont DejaVu Sans:size=8 xftalpha 0.8 text_buffer_size 2048 # Update interval in seconds update_interval 3.0 # Minimum size of text area # minimum_size 250 5 # Draw shades? draw_shades no # Text stuff draw_outline no # amplifies text if yes draw_borders no uppercase no # set to yes if you want all text to be in uppercase # Stippled borders? stippled_borders 3 # border margins border_margin 9 # border width border_width 10 # Default colors and also border colors, grey90 == #e5e5e5 default_color grey own_window_colour brown own_window_transparent yes # Text alignment, other possible values are commented #alignment top_left alignment top_right #alignment bottom_left #alignment bottom_right # Gap between borders of screen and text gap_x 10 gap_y 20 # stuff after 'TEXT' will be formatted on screen TEXT $color ${color orange}SYSTEM ${hr 2}$color $nodename $sysname $kernel on $machine ${color orange}CPU ${hr 2}$color ${freq}MHz Load: ${loadavg} Temp: ${acpitemp} $cpubar ${cpugraph 000000 ffffff} NAME ${goto 150}PID ${goto 200}CPU% ${goto 250}MEM% ${top name 1} ${goto 150}${top pid 1} ${goto 200}${top cpu 1} ${goto 250}${top mem 1} ${top name 2} ${goto 150}${top pid 2} ${goto 200}${top cpu 2} ${goto 250}${top mem 2} ${top name 3} ${goto 150}${top pid 3} ${goto 200}${top cpu 3} ${goto 250}${top mem 3} ${top name 4} ${goto 150}${top pid 4} ${goto 200}${top cpu 4} ${goto 250}${top mem 4} ${color orange}MEMORY / DISK ${hr 2}$color RAM: $memperc% ${membar 6}$color Swap: $swapperc% ${swapbar 6}$color Home: ${fs_free_perc /home}% ${fs_bar 6 /}$color Free Space: ${fs_free /home} ${color orange}NETWORK (${addr eth0}) ${hr 2}$color Down: $color${downspeed eth0} k/s ${alignr}Up: ${upspeed eth0} k/s ${downspeedgraph eth0 25,140 000000 ff0000} ${alignr}${upspeedgraph eth0 25,140 000000 00ff00}$color Total: ${totaldown eth0} ${alignr}Total: ${totalup eth0} ${execi 30 netstat -ept | grep ESTAB | awk '{print $9}' | cut -d: -f1 | sort | uniq -c | sort -nr} ${color orange}WIRELESS (${addr wlan0}) ${hr 2}$color Down: $color${downspeed wlan0} k/s ${alignr}Up: ${upspeed wlan0} k/s ${downspeedgraph wlan0 25,140 000000 ff0000} ${alignr}${upspeedgraph wlan0 25,140 000000 00ff00}$color Total: ${totaldown wlan0} ${alignr}Total: ${totalup wlan0} ${execi 30 netstat -ept | grep ESTAB | awk '{print $9}' | cut -d: -f1 | sort | uniq -c | sort -nr}

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• ArchBeat Link-o-Rama for 2012-08-29

  - by Bob Rhubart

  ORCLville: OOW 2012 - Crystal BallOracle ACE Director Floyd Teter cooks up some tongue-in-cheek predictions for news and announcements that might come out of Oracle OpenWorld 2012. What's your prediction? Oracle Optimized Solutions at Oracle OpenWorld 2012 | Oracle Hardware Hardware matters, too! The people behind the Oracle Hardware blog have put together a list of Oracle Openworld 2012 sessions focused Oracle Optimized Solutions, "designed, pre-tested, tuned and fully documented architectures for optimal performance and availability." Just plug the session ID numbers into Schedule Builder and you're good to go. AIX Checklist for stable OBIEE deployment | Dick Dunbar "OBIEE is a complicated system with many moving parts and connection points," according to Oracle Business Inteligence escalation engineer Dick Dunbar. "The purpose of this article is to provide a checklist to discuss OBIEE deployment with your systems administrators." Demo for OPN: Coherence Management with EM Cloud Control 12c Oracle Partner Network members can check out a new Coherence Management demo that showcases some of the key capabilities of Management Pack for Oracle Coherence and JVM Diagnostics. "The demo flow showcases the key enhancements made in Enterprise Manager 12c release which includes new customizable performance summary, cache data management and configuration management," according to the WebLogic Partner Community EMEA blog. The Pragmatic Architect: To Boldly Go Where No One Has Gone Before | Frank Buschmann "Many architects have technical knowledge that's both impressive and sound, which is indeed an inevitable basis for design success," says Frank Buschmann. "Yet, a lot of software projects fail or suffer due to severe challenges in their architecture. The key to mastery is how architects approach design, what they value, and where they focus their attention and work." As retail dies, whom will be the winners? | Peter Evans-Greenwood "The problem for many retailers is that how consumers shop has changed but the the retailers haven't adapted, " says Peter Evans-Greenwood. "Their sole virtue was to be the last step in a supply chain delivering somebody else's products to the consumer. However, being the last step in the supply chain is no longer a virtue when consumers skip across channels and can reach around the globe, no longer dependant on or limited to what they can find locally." Thought for the Day "Brains require stimulation. If you're locked into a pattern of work, work, and more work, your brain soon habituates - the same way that it lets you stop hearing a clock ticking. So, if you want to be more effective at work, you must, paradoxically, be less single-minded in your devotion to work. Anything you do—anything—that stimulates new segments of your brain will make you a more effective programmer or analyst. I promise, with a money-back guarantee." — Gerald M. Weinberg Source: SoftwareQuotes.com

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• Is there a pedagogical game engine?

  - by K.G.

  I'm looking for a book, website, or other resource that gives modern 3D game engines the same treatment as Operating Systems: Design and Implementation gave operating systems. I have read Jason Gregory's Game Engine Architecture, which I enjoyed. However, by intent the author treated components of the architecture as atomic units, whereas what I'm interested in is the plumbing between those units that makes a coherent whole out of ideally loosely coupled parts. In books such as these, one usually reads that "that's academic," but that's the point! I have also read Julian Gold's Object-oriented Game Development, which likewise was good, but I feel is beginning to show its age. Since even mobile platforms these days are multicore and have fast video memory, those kinds of things (concurrency, display item buffering) would ideally be covered. There are other resources, such as the Doom 3 source code, which is highly instructive for its being a shipped product. The problem with those is as follows: float Q_rsqrt( float number ) { long i; float x2, y; const float threehalfs = 1.5F; x2 = number * 0.5F; y = number; i = * ( long * ) &y; // evil floating point bit level hacking i = 0x5f3759df - ( i >> 1 ); // what the f***? y = * ( float * ) &i; y = y * ( threehalfs - ( x2 * y * y ) ); // 1st iteration // y = y * ( threehalfs - ( x2 * y * y ) ); // 2nd iteration, this can be removed return y; } To wit, while brilliant, this kind of source requires more enlightenment than I can usually muster upon first read. In summary, here's my white whale: For an adult reader with experience in programming. I wish I could save all the trees killed by every. Single. Game Programming book ever devoting the first two chapters to "Now just what is a variable anyway?" In C or C++, very preferably C++. Languages that are more concise are fantastic for teaching, except for when what you want to learn is how to cope with a verbose language. There is also the benefit of the guardrails that C++ doesn't provide, such as garbage collection. Platform agnostic. I'm sincerely afraid that this book is out there and it's Visual C++/DirectX oriented. I'm a Linux guy, and I'd do what it takes, but I would very much like to be able to use OpenGL. Thanks for everything! Before anyone gets on my case about it, Fast inverse square root was from Quake III Arena, not Doom 3!

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• What algorithms can I use to detect if articles or posts are duplicates?

  - by michael

  I'm trying to detect if an article or forum post is a duplicate entry within the database. I've given this some thought, coming to the conclusion that someone who duplicate content will do so using one of the three (in descending difficult to detect): simple copy paste the whole text copy and paste parts of text merging it with their own copy an article from an external site and masquerade as their own Prepping Text For Analysis Basically any anomalies; the goal is to make the text as "pure" as possible. For more accurate results, the text is "standardized" by: Stripping duplicate white spaces and trimming leading and trailing. Newlines are standardized to \n. HTML tags are removed. Using a RegEx called Daring Fireball URLs are stripped. I use BB code in my application so that goes to. (ä)ccented and foreign (besides Enlgish) are converted to their non foreign form. I store information about each article in (1) statistics table and in (2) keywords table. (1) Statistics Table The following statistics are stored about the textual content (much like this post) text length letter count word count sentence count average words per sentence automated readability index gunning fog score For European languages Coleman-Liau and Automated Readability Index should be used as they do not use syllable counting, so should produce a reasonably accurate score. (2) Keywords Table The keywords are generated by excluding a huge list of stop words (common words), e.g., 'the', 'a', 'of', 'to', etc, etc. Sample Data text_length, 3963 letter_count, 3052 word_count, 684 sentence_count, 33 word_per_sentence, 21 gunning_fog, 11.5 auto_read_index, 9.9 keyword 1, killed keyword 2, officers keyword 3, police It should be noted that once an article gets updated all of the above statistics are regenerated and could be completely different values. How could I use the above information to detect if an article that's being published for the first time, is already existing within the database? I'm aware anything I'll design will not be perfect, the biggest risk being (1) Content that is not a duplicate will be flagged as duplicate (2) The system allows the duplicate content through. So the algorithm should generate a risk assessment number from 0 being no duplicate risk 5 being possible duplicate and 10 being duplicate. Anything above 5 then there's a good possibility that the content is duplicate. In this case the content could be flagged and linked to the article's that are possible duplicates and a human could decide whether to delete or allow. As I said before I'm storing keywords for the whole article, however I wonder if I could do the same on paragraph basis; this would also mean further separating my data in the DB but it would also make it easier for detecting (2) in my initial post. I'm thinking weighted average between the statistics, but in what order and what would be the consequences...

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• Problem with OpenGL or Unity, need Gnome fallback mode

  - by William Wind

  This question is in two parts, and I have been searching the web for days to find answers. With no luck I thought I'd drop by and ask for your help. Here goes: 1.) I'm running Ubuntu 13.04 and one day last week Unity suddenly wound't work. After the login screen, I was either faced with an all black and non-responsive screen, or sometimes it booted and I could see my desktop wallpaper (and add and remove icons/folders from the desktop). But there was no menu in the left hand side and no top bar :-( However I could still enter the terminal. I borrowed my dad's laptop and looked for a solution online. About two days later I gave up (I'm still kind of a n00b at Linux) and found a way to install Gnome Fallback, via the terminal. When I used it, I had the same problem. [clue #1] Missing menues. But if I rebooted into Gnome Fallback mode with no effects. It worked. Great! I have used that for some days now, while still trying to fix the original problem with either Unity or OpenGl or whatever went wrong in the first place. With no luck. After giving up on my search for a fix (I know that came out wrong) -- I decided to reinstall Ubuntu 13.04 from a CD. But! After that I was left where I began. When booting into my account, it only shows the desktop wallpaper and the icons. I can click and enter the folders, but not go into the menues. Last time I fixed it with Gnome Fallback mode, because I could enter the terminal and the PC was automatically online, via wireless network. But not this time, I can't get online. So: 1.) How do I via the LiveCD Ubuntu version (the one I'm using right now) install Gnome Fallback unto the harddrive based system? 2.) If impossible. How can I access the wireless Internet via the terminal, so I can install Gnome Fallback, from the "broken" Unity session. 3.) Is there any other things that I should try? Please help me, PS: My GFX-card is an ATI Radeon something and I have install and used the "Redwood" drive (I think its called) for many weeks prior to the shutdown.

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• Unable to connect to mail server via IMAP and roundcube

  - by mrhatter

  I am having trouble getting the final parts of my mail server up and working. I followed this tutorial to get everything set up on the mail server side. I have installed roundcube for webmail and configured it but it is saying "error connecting, connection refused" when attempting to connect to it using IMAP. This is thorough the "test imap" section of its installer. Also it is giving me an error message about perissions for it's log and temp folders but that's not as important as acutally getting mail to work. I have also tried connecting to the mail server using thunderbird however it cannot establish a connection either and I know my login information is correct. I know that the databases are working correctly based on the roundcube installer telling me that they have been "successfully initialized". Here are my firewall rules -A INPUT -i lo -j ACCEPT -A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT -A INPUT -p tcp -m tcp --dport 22 -j ACCEPT -A INPUT -p tcp -m tcp --dport 25 -j ACCEPT -A INPUT -p tcp -m tcp --dport 80 -j ACCEPT -A INPUT -p tcp -m tcp --dport 443 -j ACCEPT -A INPUT -p tcp -m tcp --dport 465 -j ACCEPT -A INPUT -p tcp -m tcp --dport 487 -j ACCEPT -A OUTPUT -p tcp -m tcp --dport 993 -j ACCEPT -A INPUT -j DROP Which I set up in iptables. I have modified them from what I used in this tutorial I'm not sure what to try next. Any help would be wonderful! I am using Ubuntu 14.04 server, apache 2.4.7, roundcube 1.0.1, and the latest versions of dovecot and postfix. The email databases are contained in mysql. I am running this on a VPS server. UPDATE: I have changed from iptables to using ufw. I have run the following commands to set up a basic firewall with ufw. ufw default deny ufw allow ssh ufw allow http ufw allow https ufw allow imap ufw allow imaps ufw allow smtp I then used telnet to check all of the mail ports. But Port 993 isnt working even though ufw says both 993 and 993/tcp are open. What am I missing?

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• How to determine the source of a request in a distributed service system?

  - by Kabumbus

  Map/Reduce is a great concept for sorting large quantities of data at once. What to do if you have small parts of data and you need to reduce it all the time? Simple example - choosing a service for request. Imagine we have 10 services. Each provides services host with sets of request headers and post/get arguments. Each service declares it has 30 unique keys - 10 per set. service A: name id ... Now imagine we have a distributed services host. We have 200 machines with 10 services on each. Each service has 30 unique keys in there sets. but now to find to which service to map the incoming request we make our services post unique values that map to that sets. We can have up to or more than 10 000 such values sets on each machine per each service. service A machine 1 name = Sam id = 13245 ... service A machine 1 name = Ben id = 33232 ... ... service A machine 100 name = Ron id = 777888 ... So we get 200 * 10 * 30 * 30 * 10 000 == 18 000 000 000 and we get 500 requests per second on our gateway each containing 45 items 15 of which are just noise. And our task is to find a service for request (at least a machine it is running on). On all machines all over cluster for same services we have same rules. We can first select to which service came our request via rules filter 10 * 30. and we will have 200 * 30 * 10 000 == 60 000 000. So... 60 mil is definitely a problem... I hope to get on idea of mapping 30 * 10 000 onto some artificial neural network alike Perceptron that outputs 1 if 30 words (some hashes from words) from the request are correct or if less than Perceptron should return 0. And I’ll send each such Perceptron for each service from each machine to gateway. So I would have a map Perceptron <-> machine for each service. Can any one tall me if my Perceptron idea is at least “sane”? Or normal people do it some other way? Or if there are better ANNs for such purposes?

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• One Year Oracle SocialChat - The Movie

  - by mprove

  Tweet | Like | Watch on Vimeo You’ve just watched – hopefully – my first short movie. Thank you! Here is a bit of the back stage story. About 6 weeks ago colleagues from SNBC (Social Network and Business Collaboration) announced a Social Use Case Competition. It was expected to submit a video of 2 to 5 minutes duration on the Social Enterprise (our internal phrase for Enterprise 2.0). Hmm – I had a few vague ideas, but no script – no actors – no experience in film making. Really the best conditions to try something! I chose our weekly SocialChats as my main topic. But if you don’t do Danish Dogma cinema, you still need a script. Hence I played around with the SocialChat’s archive, and all of a sudden a script and even the actors appeared in front of me. The words that you have just seen are weekly topics. Slightly abridged and rearranged to form a story. Exciting, next phase. How to get it on digital celluloid? I have to confess I am still impressed by epic. (Keep in mind, epic was done in 2004.) And my actors – words – call for a typographic style already. The main part was done over a weekend with Apple Keynote. And I even found a wonderful matching soundtrack among my albums: Didge Goes World by Delago. I picked parts of Second Day and Seventh Day. Literally, the rhythm was set, and I "just" had to complete the movie. Tools used – apart from trial and error: Keynote, Pixelmator, GarageBand, iMovie. Finally I want to mention that I am extremely thankful to BSC Music for granting permissions to use the tracks for this short film! Without this sound it would have been just an ordinary slide show. – Internal note: The next SocialChat is on Death by PowerPoint vs. Presentation Zen. CU this Friday 3pm Greenwich / 7am Pacific.

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• What could be the best way to generalize data from Facebook and Twitter?

  - by Sjaak van der Heide

  I am not sure if this is the best subsite to ask this question, but I'm pretty sure it doesn't fit on the normal or facebook SO page... I've been asked to make a general API for connecting to several Social Media platforms (at the moment Facebook and Twitter). I have already realised both of them seperately. Meaning I retrieve the data I need from both Facebook and Twitter and hold the data in it's own dataclass. In my case a list of FacebookTimelineItems and a list of TwitterTimelineItems. now the hard part is taking the parts that are used in both (username, id, message and such) and make 1 general class that is eventually passed on to who/whatever sent the call to my API. these are two pics of the data classes I have: http://imageshack.us/photo/my-images/703/facebookdata.png/ http://imageshack.us/photo/my-images/204/twitterdata.png/ probably not 100% correct but it gives an idea what it looks like. Now I've been having several idea about how to go about and generalize the two, which is harder then I thought at first. Create an interface (TimelineItem) and let the other classes extend that one. this way I'll always be sure I have a class that contains at least the basic info I need. downside is that deserializing the JSON seems to be a nightmare. Use the two dataclasses I have and combine them into a new class afterwards, then pass that one back to whoever requested it. This would probably work but I get the idea it's not the best way to tackle this problem, and is pretty dodgy IF I get it working. Or, in case of the other two being nearly impossible. Keep the two seperated in the front end, and go sit in the corner crying because I've just figured out you can't lump together facebook and twitter... Note: I don't have to make the front end part (view), I just make sure the Model is nicely filled with data :) I hope I placed this in the right section, if I didn't I apologise and would like to know where I should go with my question. Thanks in advance for any replied/ideas/opinions on this.

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• What shall I include in a 10 week web technologies course?

  - by Iain

  In September I will be teaching a university module on web technologies. This session will be available to 1st year (freshman) students who don't necessarily have any programming knowledge or know how the web works. In the 2nd semester I will be teaching Flash, which is my specialism, so I know exactly what I am going to teach, but in the 1st semester I will be teaching them web standards technologies - HTML, CSS, JS, jQuery, PHP and MySQL. Where I need advice is how to proportion the emphasis for each part, and which parts of each technology to cover. Another real issue I'm struggling with is how much of the bad old ways should I teach them? Do they need to know about bold as well as strong, etc. UPDATE: based, on your feedback I will only be teaching the latest version of everything - CSS3, HTML5 etc. I'm not sure exactly how long the semester will be but I'm guessing about 10-12 weeks. Each session is a 2 hour lab. Obviously there's only so much I can cover in that time and it will be up to the students to go a research this stuff properly on W3 schools etc. My ideas so far were: Lesson 0 - Course intro and overview of the current tech landscape. What is out there, what will we be learning, what won't we. What is a web server, URL etc. Looking at different example websites and discussing how they work. Lesson 1 - HTML basics (head, body, title, img, table, a, lists, h1, strong etc) Lesson 2 - CSS for styling and layout - fonts, webfonts, float etc Lesson 3 - Intro to programming JS (variables, loops, conditionals, functions) Lesson 4 - more JS programming fundamentals, DOM manipulation Lesson 5 - jQuery - making things fly about and look cool Lesson 6 - XML and Ajax Lesson 7 - PHP basics - syntax, server-side principles Lesson 8 - PHP and MySQL - forms, logins, saving user info Lesson 9 - don't know Lesson 10 - don't know Please let me know if you think this is the right order, what have I missed, how to use any spare sessions etc. Thanks :) UPDATE BASED ON RESPONSES: Thanks for all your responses - some great stuff. To be absolutely clear, this is not a computer science course, it is a practical module on a creative technology course. The emphasis definitely has to be on making cool things work rather than understanding how the backbone of the internet works. That can come later, if the students are interested. At the end of the module I would like the students to be able to produce a web page or pages that does something cool, using some or all of the technologies I cover. Many of these topics are of course far beyond the scope of a 2 hour session, however I do not have the option of reducing the syllabus, I will just have to explain what the technology does and encourage the student to research it in their own time.

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• Caching items in Orchard

  - by Bertrand Le Roy

  Orchard has its own caching API that while built on top of ASP.NET's caching feature adds a couple of interesting twists. In addition to its usual work, the Orchard cache API must transparently separate the cache entries by tenant but beyond that, it does offer a more modern API. Here's for example how I'm using the API in the new version of my Favicon module: _cacheManager.Get( "Vandelay.Favicon.Url", ctx => { ctx.Monitor(_signals.When("Vandelay.Favicon.Changed")); var faviconSettings = ...; return faviconSettings.FaviconUrl; }); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } There is no need for any code to test for the existence of the cache entry or to later fill that entry. Seriously, how many times have you written code like this: var faviconUrl = (string)cache["Vandelay.Favicon.Url"]; if (faviconUrl == null) { faviconUrl = ...; cache.Add("Vandelay.Favicon.Url", faviconUrl, ...); } Orchard's cache API takes that control flow and internalizes it into the API so that you never have to write it again. Notice how even casting the object from the cache is no longer necessary as the type can be inferred from the return type of the Lambda. The Lambda itself is of course only hit when the cache entry is not found. In addition to fetching the object we're looking for, it also sets up the dependencies to monitor. You can monitor anything that implements IVolatileToken. Here, we are monitoring a specific signal ("Vandelay.Favicon.Changed") that can be triggered by other parts of the application like so: _signals.Trigger("Vandelay.Favicon.Changed"); In other words, you don't explicitly expire the cache entry. Instead, something happens that triggers the expiration. Other implementations of IVolatileToken include absolute expiration or monitoring of the files under a virtual path, but you can also come up with your own.

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• Handling bugs, quirks, or annoyances in vendor-supplied headers

  - by supercat

  If the header file supplied by a vendor of something with whom one's code must interact is deficient in some way, in what cases is it better to: Work around the header's deficiencies in the main code Copy the header file to the local project and fix it Fix the header file in the spot where it's stored as a vendor-supplied tool Fix the header file in the central spot, but also make a local copy and try to always have the two match Do something else As an example, the header file supplied by ST Micro for the STM320LF series contains the lines: typedef struct { __IO uint32_t MODER; __IO uint16_t OTYPER; uint16_t RESERVED0; .... __IO uint16_t BSRRL; /* BSRR register is split to 2 * 16-bit fields BSRRL */ __IO uint16_t BSRRH; /* BSRR register is split to 2 * 16-bit fields BSRRH */ .... } GPIO_TypeDef; In the hardware, and in the hardware documentation, BSRR is described as a single 32-bit register. About 98% of the time one wants to write to BSRR, one will only be interested in writing the upper half or the lower half; it is thus convenient to be able to use BSSRH and BSSRL as a means of writing half the register. On the other hand, there are occasions when it is necessary that the entire 32-bit register be written as a single atomic operation. The "optimal" way to write it (setting aside white-spacing issues) would be: typedef struct { __IO uint32_t MODER; __IO uint16_t OTYPER; uint16_t RESERVED0; .... union // Allow BSRR access as 32-bit register or two 16-bit registers { __IO uint32_t BSRR; // 32-bit BSSR register as a whole struct { __IO uint16_t BSRRL, BSRRH; };// Two 16-bit parts }; .... } GPIO_TypeDef; If the struct were defined that way, code could use BSRR when necessary to write all 32 bits, or BSRRH/BSRRL when writing 16 bits. Given that the header isn't that way, would better practice be to use the header as-is, but apply an icky typecast in the main code writing what would be idiomatically written as thePort->BSRR = 0x12345678; as *((uint32_t)&(thePort->BSSRH)) = 0x12345678;, or would be be better to use a patched header file? If the latter, where should the patched file me stored and how should it be managed?

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• C Minishell Command Expansion Printing Gibberish

  - by Optimus_Pwn

  I'm writing a unix minishell in C, and am at the point where I'm adding command expansion. What I mean by this is that I can nest commands in other commands, for example: $> echo hello $(echo world! ... $(echo and stuff)) hello world! ... and stuff I think I have it working mostly, however it isn't marking the end of the expanded string correctly, for example if I do: $> echo a $(echo b $(echo c)) a b c $> echo d $(echo e) d e c See it prints the c, even though I didn't ask it to. Here is my code: msh.c - http://pastebin.com/sd6DZYwB expand.c - http://pastebin.com/uLqvFGPw I have a more code, but there's a lot of it, and these are the parts that I'm having trouble with at the moment. I'll try to tell you the basic way I'm doing this. Main is in msh.c, here it gets a line of input from either the commandline or a shellfile, and then calls processline (char *line, int outFD, int waitFlag), where line is the line we just got, outFD is the file descriptor of the output file, and waitFlag tells us whether or not we should wait if we fork. When we call this from main we do it like this: processline (buffer, 1, 1); In processline, we allocate a new line: char expanded_line[EXPANDEDLEN]; We then call expand, in expand.c: expand(line, expanded_line, EXPANDEDLEN); In expand, we copy the characters literally from line to expanded_line until we find a $(, which then calls: static int expCmdOutput(char *orig, char *new, int *oldl_ind, int *newl_ind) orig is line, and new is expanded line. oldl_ind and newl_ind are the current positions in the line and expanded line, respectively. Then we pipe, and recursively call processline, passing it the nested command(for example, if we had "echo a $(echo b)", we would pass processline "echo b"). This is where I get confused, each time expand is called, is it allocating a new chunk of memory EXPANDEDLEN long? If so, this is bad because I'll run out of stack room really quickly(in the case of a hugely nested commandline input). In expand I insert a null character at the end of the expanded string, so why is it printing past it? If you guys need any more code, or explanations, just ask. Secondly, I put the code in pastebin because there's a ton of it, and in my experience people don't like it when I fill up several pages with code. Thanks.

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• Travelling at Magenic

  - by Chris G. Williams

  I occasionally get asked if we travel "a lot" at Magenic. Sometimes the question comes from job candidates. Other times it's clients, recruiters or friends. To give a simple yes or no answer would be a disservice to the person asking the question. So here is my standard answer:It depends.(That was the short version.  Here's the long version...)We do have some guys that are more "national" in focus, and they can travel a fair amount. They also receive a little extra in compensation for doing so. It's a balancing act, and not necessarily a one-size-fits-all situation. Not everyone is well suited to constant travel. Some folks enjoy it and some folks hate it.With our local guys, our general policy is to TRY and keep them close to home whenever possible, but sometimes the needs of the client will dictate otherwise. (As Spock would say... the needs of the many outweigh the needs of the few, or the one.)In most cases though, we really do try to avoid sending our guys on extended travel gigs (i.e. every week for 6 months) when a simple kickoff trip and occasional visit will do. This depends on the nature of the gig, of course. Some types of work lend themselves to this model better than others. Additionally, this can and does vary by office. If one office is having trouble staffing a gig (not enough available bodies) and another office has a few too many folks on the bench, well... you can connect the dots. But again, we try to keep that to a minimum.Lastly, we all have our own thresholds for what we consider "a lot" of travel. There are two parts to this threshold:Half of it is whatever you're accustomed to already. The other half is being honest with yourself about how much you [like/hate] dealing with airports, car rentals, taxis, hotels, disruptions to your workout schedule, time away from friends/family, etc.Knowing a bit about yourself will definitely help you decide how much travel is too much for you.

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• Modelling highly specific business requirements

  - by AndyBursh

  How can one go about modelling highly specific business requirements, which have no precedent in the system? Take for example the following requirement: When a purchase order contains N lines, is over X value in total and is being recorded against project Y, an email needs to be sent to persons A and B with the details This requirement supplements other requirements surrounding purchase orders, but comes in at a much later date in response to some ongoing problem elsewhere in the business. Persons A and B are not part of any role or group in the system, and don't hold any specific responsibility; they are simply the two people the business has appointed to receive these emails in this very specific case. Projects are also data driven, so project Y has no special properties to distinguish it from any other project. The only way to identify it is to compare its identifier to a magic number. How can one go about modelling this kind of case without introducing too much additional complexity? That I can think of right now, there are a couple of options. Perform the checks and actions inline with the existing code. Here we find the correct spot in the code, check the conditions in the requirement and send the emails to hardcoded addresses. Of course this is fraught with issues. At the very least it stops working if one of these people leaves or changes their email address. At worst you have to ensure that any tests and test data are aware that additional actions are taken for a specific set of criteria. Introduce some form of events system. Here we introduce an eventing system, so that we might react to some event, and fulfil the requirement outside of the usual path of execution. This sounds like a cleaner solution than option 1, but the work involved is ultimately probably slightly overkill for this one small requirement. That said, having it in place does allow the system to handle these kinds of specific requirements consistently and easily in the future. Are there any other (good/better) ways of handling highly specific requirements? I mean other than telling the other parts of the business no!

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• RTS Game Style Application [closed]

  - by Daniel Wynand van Wyk

  My question may seem somewhat odd, but I hope that my specifications will clarify EXACTLY what it is that I am after. I need some help choosing the right tooling for a particular endeavour. My background is in desktop application development and large back-end systems. I have worked primarily on the Microsoft stack using C# and the .Net framework. My goal is to develop a 2D, RTS style, interactive office simulation. The simulation will model various office spaces, office equipment, employees and their interactions with one another. The idea is to abstract the concept of an office completely. Under the hood the application will do many things that are nothing like a game. This includes P2P networking, VPN tunnelling, streaming video, instant messaging, document collaboration, remote screen sharing, file-sharing, virus scanning, VOIP, document scanning, faxing, emailing, distributed computing, content management and much more! A somewhat similar thing has been attempted by IBM, where they created a virtual office in second life. If their attempt was a game, the game-play would be notably horrible, to say the least! The users/players will drive and control my application through the various objects modelled in the simulation. A single application capable of performing all of these various tasks would be a nightmare to navigate for even the most expert user. Using the concept of a game, I can easily separate functionality by assigning them to objects that relate 1-1 with their real world counter-parts. This can greatly simplify computing for novice users, with many added benefits in terms of visibility, transparency of process and centralized configuration. My hope is to make complex computing tasks accessible to all kinds of users and to greatly reduce the cognitive load associated with using the many different utilities and applications inside office settings. The complexity is therefore limited to the complexity of the space in which you find yourself. I want the application to target as many platforms as possible and run on computers that have no accelerated graphics capabilities. The simulation won't contain any of the fancy eye-candy you find in modern games, to the contrary, my "game" will purposefully be clean and simple. The closest thing I could imagine would be an old game like "Theme Hospital" or the first instalment of "The Sims". All the content will be pre-created and not user-generated like Second Life. New functionality will be added via a plugin system. Given my background and nature of my "game", I would like to spend most of my time writing code that does not have to do with the simulated office, as the "game" is really just a glorified application menu. I have done much reading about existing engines, frameworks and tools. I need the help of an experienced game developer who has tried and tested various products over the years who can guide me in the right direction given my very particular needs. I would appreciate any help I can get!

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• How is fundamental mathematics efficiently evaluated by programming languages?

  - by Korvin Szanto

  As I get more and more involved with the theory behind programming, I find myself fascinated and dumbfounded by seemingly simple things.. I realize that my understanding of the majority of fundamental processes is justified through circular logic Q: How does this work? A: Because it does! I hate this realization! I love knowledge, and on top of that I love learning, which leads me to my question (albeit it's a broad one). Question: How are fundamental mathematical operators assessed with programming languages? How have current methods been improved? Example var = 5 * 5; My interpretation: $num1 = 5; $num2 = 5; $num3 = 0; while ($num2 > 0) { $num3 = $num3 + $num1; $num2 = $num2 - 1; } echo $num3; This seems to be highly inefficient. With Higher factors, this method is very slow while the standard built in method is instantanious. How would you simulate multiplication without iterating addition? var = 5 / 5; How is this even done? I can't think of a way to literally split it 5 into 5 equal parts. var = 5 ^ 5; Iterations of iterations of addition? My interpretation: $base = 5; $mod = 5; $num1 = $base; while ($mod > 1) { $num2 = 5; $num3 = 0; while ($num2 > 0) { $num3 = $num3 + $num1; $num2 = $num2 - 1; } $num1 = $num3; $mod -=1; } echo $num3; Again, this is EXTREMELY inefficient, yet I can't think of another way to do this. This same question extends to all mathematical related functions that are handled automagically.

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• Access Control Service v2: Registering Web Identities in your Applications [code]

  - by Your DisplayName here!

  You can download the full solution here. The relevant parts in the sample are: Configuration I use the standard WIF configuration with passive redirect. This kicks automatically in, whenever authorization fails in the application (e.g. when the user tries to get to an area the requires authentication or needs registration). Checking and transforming incoming claims In the claims authentication manager we have to deal with two situations. Users that are authenticated but not registered, and registered (and authenticated) users. Registered users will have claims that come from the application domain, the claims of unregistered users come directly from ACS and get passed through. In both case a claim for the unique user identifier will be generated. The high level logic is as follows: public override IClaimsPrincipal Authenticate( string resourceName, IClaimsPrincipal incomingPrincipal) {     // do nothing if anonymous request     if (!incomingPrincipal.Identity.IsAuthenticated)     {         return base.Authenticate(resourceName, incomingPrincipal);     } string uniqueId = GetUniqueId(incomingPrincipal);     // check if user is registered     RegisterModel data;     if (Repository.TryGetRegisteredUser(uniqueId, out data))     {         return CreateRegisteredUserPrincipal(uniqueId, data);     }     // authenticated by ACS, but not registered     // create unique id claim     incomingPrincipal.Identities[0].Claims.Add( new Claim(Constants.ClaimTypes.Id, uniqueId));     return incomingPrincipal; } User Registration The registration page is handled by a controller with the [Authorize] attribute. That means you need to authenticate before you can register (crazy eh? ;). The controller then fetches some claims from the identity provider (if available) to pre-fill form fields. After successful registration, the user is stored in the local data store and a new session token gets issued. This effectively replaces the ACS claims with application defined claims without requiring the user to re-signin. Authorization All pages that should be only reachable by registered users check for a special application defined claim that only registered users have. You can nicely wrap that in a custom attribute in MVC: [RegisteredUsersOnly] public ActionResult Registered() {     return View(); } HTH

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• LINQ to Twitter v2.1.09 Released

  - by Joe Mayo

  Originally posted on: http://geekswithblogs.net/WinAZ/archive/2013/10/15/linq-to-twitter-v2.1.09-released.aspxToday, I released LINQ to Twitter v2.1.09. Here are important new changes. Bug Fixes This is primarily a bug fix release. Most notably, there were authentication problems in WinRT apps. This is now fixed. New Features One new feature is the addition of ApplicationOnlyAuthentication for WinRT. It is fully async.  Here’s how it works: var auth = new WinRtApplicationOnlyAuthorizer { Credentials = new InMemoryCredentials { ConsumerKey = "", ConsumerSecret = "" } }; if (auth == null || !auth.IsAuthorized) { await auth.AuthorizeAsync(); } var twitterCtx = new TwitterContext(auth); (from search in twitterCtx.Search where search.Type == SearchType.Search && search.Query == SearchTextBox.Text select search) .MaterializedAsyncCallback( async response => await Dispatcher.RunAsync( CoreDispatcherPriority.Normal, async () => { Search searchResponse = response.State.Single(); string message = string.Format( "Search returned {0} statuses", searchResponse.Statuses.Count); await new MessageDialog(message, "Search Complete").ShowAsync(); })); It’s called the WinRtApplicationOnlyAuthorizer. You only need two tokens, ConsumerKey and ConsumerSecret, which come from your Twitter API application settings page. Note: You need a Twitter Application, which you can create at https://dev.twitter.com/. The MaterializedAsyncCallback materializes your query and handles the response. I put everything together in a lambda for demonstration purposes, but you can always replace the callback with a handler of type Action<TwitterAsyncResponse<IEnumerable<T>>>, where T is Search for this example. On the Horizon The next version of LINQ to Twitter is in development. I discussed it at LINQ to Twitter Async. This isn’t complete, but you can download the source code at the LINQ to Twitter site on CodePlex. I’ve competed all the spikes for what I thought would be the hard parts and now have prototypes of queries and commands working. This would be a good time to provide feedback if there are features in the current version that you think could be improved. The current driving forces for the next version will be async and PCL.   @JoeMayo

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• Rending 2D Tile World (With Player In The Middle)

  - by Mick

  What I have at the moment is a series of data structures I'm using, and I would like to render the world onto the screen (just the visible parts). I've actually already done this several times (lots of rewrites), but it's a bit buggy (rounding seems to make the screen jump ever so slightly every x tiles the player walks past). Basically I've been confusing myself heavily on what I feel should be a pretty simple problem... so here I am asking for some help! OK! So I have a 50x50 array holding the tiles of the world. I have the player position as 2 floats, x ([0, 49]) and y ([0, 49]) in that array. I have the application size exactly in pixels (x and y). I have an arbitrary TILE_SIZE static int (based on screen pixels). What I think is heavily confusing me is using a 2d orthogonal projection in opengl which maps (0,0) to the top left of the screen and (SCREEN_SIZE_X, SCREEN_SIZE_Y) to the bottom right of the screen. gl.glMatrixMode(GL.GL_PROJECTION); gl.glLoadIdentity(); glu.gluOrtho2D(0, getActualWidth(), getActualHeight(), 0); gl.glMatrixMode(GL.GL_MODELVIEW); gl.glLoadIdentity(); The map tiles are set so that the (0,0) in the array is the bottom left. And the player has to be in the middle on the screen (SCREEN_SIZE_X/2, SCREEN_SIZE_Y/2). What I've been doing so far is trying to render 1-2 tiles more all around what would be displayed on the screen so that I don't have to worry about figuring out rendering half a tile from the top left, depending where the player is. It seems like such an easy problem but after spending about 40+hours on it rewriting it many times I think I'm at a point where I just can't think clearly anymore... Any help would be appreciated. It would be great if someone can provide some very basic pseudo code on keeping the player in the middle when your projection is mapped to screen coordinates and only rendering basically the tiles that you would be any be see. Thanks!

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• Are closures with side-effects considered "functional style"?

  - by Giorgio

  Many modern programming languages support some concept of closure, i.e. of a piece of code (a block or a function) that Can be treated as a value, and therefore stored in a variable, passed around to different parts of the code, be defined in one part of a program and invoked in a totally different part of the same program. Can capture variables from the context in which it is defined, and access them when it is later invoked (possibly in a totally different context). Here is an example of a closure written in Scala: def filterList(xs: List[Int], lowerBound: Int): List[Int] = xs.filter(x => x >= lowerBound) The function literal x => x >= lowerBound contains the free variable lowerBound, which is closed (bound) by the argument of the function filterList that has the same name. The closure is passed to the library method filter, which can invoke it repeatedly as a normal function. I have been reading a lot of questions and answers on this site and, as far as I understand, the term closure is often automatically associated with functional programming and functional programming style. The definition of function programming on wikipedia reads: In computer science, functional programming is a programming paradigm that treats computation as the evaluation of mathematical functions and avoids state and mutable data. It emphasizes the application of functions, in contrast to the imperative programming style, which emphasizes changes in state. and further on [...] in functional code, the output value of a function depends only on the arguments that are input to the function [...]. Eliminating side effects can make it much easier to understand and predict the behavior of a program, which is one of the key motivations for the development of functional programming. On the other hand, many closure constructs provided by programming languages allow a closure to capture non-local variables and change them when the closure is invoked, thus producing a side effect on the environment in which they were defined. In this case, closures implement the first idea of functional programming (functions are first-class entities that can be moved around like other values) but neglect the second idea (avoiding side-effects). Is this use of closures with side effects considered functional style or are closures considered a more general construct that can be used both for a functional and a non-functional programming style? Is there any literature on this topic? IMPORTANT NOTE I am not questioning the usefulness of side-effects or of having closures with side effects. Also, I am not interested in a discussion about the advantages / disadvantages of closures with or without side effects. I am only interested to know if using such closures is still considered functional style by the proponent of functional programming or if, on the contrary, their use is discouraged when using a functional style.

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• What does path finding in internet routing do and how is it different from A*?

  - by alan2here

  Note: If you don't understand this question then feel free to ask clarification in the comments instead of voting down, it might be that this question needs some more work at the moment. I've been directed here from the Stack Excange chat room Root Access because my question didn't fit on Super User. In many aspects path finding algorithms like A star are very similar to internet routing. For example: A node in an A* path finding system can search for a path though edges between other nodes. A router that's part of the internet can search for a route though cables between other routers. In the case of A*, open and closed lists are kept by the system as a whole, sepratly from any individual node as well as each node being able to temporarily store a state involving several numbers. Routers on the internet seem to have remarkable properties, as I understand it: They are very performant. New nodes can be added at any time that use a free address from a finite (not tree like) address space. It's real routing, like A*, there's never any doubling back for example. Similar IP addresses don't have to be geographically nearby. The network reacts quickly to changes to the networks shape, for example if a line is down. Routers share information and it takes time for new IP's to be registered everywhere, but presumably every router doesn't have to store a list of all the addresses each of it's directions leads most directly to. I'm looking for a basic, general, high level description of the algorithms workings from the point of view of an individual router. Does anyone have one? I presume public internet routers don't use A* as the overheads would be to large, and scale to poorly. I also presume there is a single method worldwide because it seems as if must involve a lot of transferring data to update and communicate a reasonable amount of state between neighboring routers. For example, perhaps the amount of data that needs to be stored in each router scales logarithmically with the number of routers that exist worldwide, the detail and reliability of the routing is reduced over increasing distances, there is increasing backtracking involved in parts of the network that are less geographically uniform or maybe each router really does perform an A* style search, temporarily maintaining open and closed lists when a packet arrives.

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• Are these non-standard applications of rendering practical in games?

  - by maul

  I've recently got into 3D and I came up with a few different "tricky" rendering techniques. Unfortunately I don't have the time to work on this myself, but I'd like to know if these are known methods and if they can be used in practice. Hybrid rendering Now I know that ray-tracing is still not fast enough for real-time rendering, at least on home computers. I also know that hybrid rendering (a combination of rasterization and ray-tracing) is a well known theory. However I had the following idea: one could separate a scene into "important" and "not important" objects. First you render the "not important" objects using traditional rasterization. In this pass you also render the "important" objects using a special shader that simply marks these parts on the image using a special color, or some stencil/depth buffer trickery. Then in the second pass you read back the results of the first pass and start ray tracing, but only from the pixels that were marked by the "important" object's shader. This would allow you to only ray-trace exactly what you need to. Could this be fast enough for real-time effects? Rendered physics I'm specifically talking about bullet physics - intersection of a very small object (point/bullet) that travels across a straight line with other, relatively slow-moving, fairly constant objects. More specifically: hit detection. My idea is that you could render the scene from the point of view of the gun (or the bullet). Every object in the scene would draw a different color. You only need to render a 1x1 pixel window - the center of the screen (again, from the gun's point of view). Then you simply check that central pixel and the color tells you what you hit. This is pixel-perfect hit detection based on the graphical representation of objects, which is not common in games. Afaik traditional OpenGL "picking" is a similar method. This could be extended in a few ways: For larger (non-bullet) objects you render a larger portion of the screen. If you put a special-colored plane in the middle of the scene (exactly where the bullet will be after the current frame) you get a method that works as the traditional slow-moving iterative physics test as well. You could simulate objects that the bullet can pass through (with decreased velocity) using alpha blending or some similar trick. So are these techniques in use anywhere, and/or are they practical at all?

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• Strategy for avoiding duplicate object ids for data shared across devices using iCloud

  - by rmaddy

  I have a data intensive iOS app that is not using CoreData nor does it support iCloud synching (yet). All of my objects are created with unique keys. I use a simple long long initialized with the current time. Then as I need a new key I increment the value by 1. This has all worked well for a few years with the app running isolated on a single device. Now I want to add support for automatic data sync across devices using iCloud. As my app is written, there is the possibility that two objects created on two different devices could end up with the same key. I need to avoid this possibility. I'm looking for ideas for solving this issue. I have a few requirements that the solution must meet: 1) The key needs to remain a single integral data type. Converting all existing keys to a compound key or to a string or other type would affect the entire code base and likely result in more bugs than it's worth. 2) The solution can't depend on an Internet connection. A user must be able to run the app and add data even with no Internet connection. The data should still resolve properly later when the data syncs through iCloud once a connection is available. I'll accept one exception to this rule. If no other option is available, I may be open to requiring an Internet connection the first time the app's data is initialized. One idea I have been toying around with in my head is logically splitting the integer key into two parts. The high 4 or 5 bits could be used as some sort of device id while the rest represents the actual key. The fuzzy part is figuring out how to come up with non-conflicting device ids that fit in a few bits. This should be viable since I don't need to deal will millions of devices. I just need to deal with the few devices that would be shared by a given iCloud account. I'm open to suggestions. Thanks.

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