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  • Dijkstras Algorithm exaplination java

    - by alchemey89
    Hi, I have found an implementation for dijkstras algorithm on the internet and was wondering if someone could help me understand how the code works. Many thanks private int nr_points=0; private int[][]Cost; private int []mask; private void dijkstraTSP() { if(nr_points==0)return; //algorithm=new String("Dijkstra"); nod1=new Vector(); nod2=new Vector(); weight=new Vector(); mask=new int[nr_points]; //initialise mask with zeros (mask[x]=1 means the vertex is marked as used) for(int i=0;i<nr_points;i++)mask[i]=0; //Dijkstra: int []dd=new int[nr_points]; int []pre=new int[nr_points]; int []path=new int[nr_points+1]; int init_vert=0,pos_in_path=0,new_vert=0; //initialise the vectors for(int i=0;i<nr_points;i++) { dd[i]=Cost[init_vert][i]; pre[i]=init_vert; path[i]=-1; } pre[init_vert]=0; path[0]=init_vert; pos_in_path++; mask[init_vert]=1; for(int k=0;k<nr_points-1;k++) { //find min. cost in dd for(int j=0;j<nr_points;j++) if(dd[j]!=0 && mask[j]==0){new_vert=j; break;} for(int j=0;j<nr_points;j++) if(dd[j]<dd[new_vert] && mask[j]==0 && dd[j]!=0)new_vert=j; mask[new_vert]=1; path[pos_in_path]=new_vert; pos_in_path++; for(int j=0;j<nr_points;j++) { if(mask[j]==0) { if(dd[j]>dd[new_vert]+Cost[new_vert][j]) { dd[j]=dd[new_vert]+Cost[new_vert][j]; } } } } //Close the cycle path[nr_points]=init_vert; //Save the solution in 3 vectors (for graphical purposes) for(int i=0;i<nr_points;i++) { nod1.addElement(path[i]); nod2.addElement(path[i+1]); weight.addElement(Cost[path[i]][path[i+1]]); } }

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  • Dijkstra's Algorithm explanation java

    - by alchemey89
    Hi, I have found an implementation for dijkstras algorithm on the internet and was wondering if someone could help me understand how the code works. Many thanks private int nr_points=0; private int[][]Cost; private int []mask; private void dijkstraTSP() { if(nr_points==0)return; //algorithm=new String("Dijkstra"); nod1=new Vector(); nod2=new Vector(); weight=new Vector(); mask=new int[nr_points]; //initialise mask with zeros (mask[x]=1 means the vertex is marked as used) for(int i=0;i<nr_points;i++)mask[i]=0; //Dijkstra: int []dd=new int[nr_points]; int []pre=new int[nr_points]; int []path=new int[nr_points+1]; int init_vert=0,pos_in_path=0,new_vert=0; //initialise the vectors for(int i=0;i<nr_points;i++) { dd[i]=Cost[init_vert][i]; pre[i]=init_vert; path[i]=-1; } pre[init_vert]=0; path[0]=init_vert; pos_in_path++; mask[init_vert]=1; for(int k=0;k<nr_points-1;k++) { //find min. cost in dd for(int j=0;j<nr_points;j++) if(dd[j]!=0 && mask[j]==0){new_vert=j; break;} for(int j=0;j<nr_points;j++) if(dd[j]<dd[new_vert] && mask[j]==0 && dd[j]!=0)new_vert=j; mask[new_vert]=1; path[pos_in_path]=new_vert; pos_in_path++; for(int j=0;j<nr_points;j++) { if(mask[j]==0) { if(dd[j]>dd[new_vert]+Cost[new_vert][j]) { dd[j]=dd[new_vert]+Cost[new_vert][j]; } } } } //Close the cycle path[nr_points]=init_vert; //Save the solution in 3 vectors (for graphical purposes) for(int i=0;i<nr_points;i++) { nod1.addElement(path[i]); nod2.addElement(path[i+1]); weight.addElement(Cost[path[i]][path[i+1]]); } }

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  • How to mask an view with an black-white image?

    - by mystify
    I've heard that it's possible to mask views with black/white images, where black means fully transparent and white means view is visible. The big difference to clipsToBounds is that the view could be clipped in funny shapes like circles or stars. How could I do that?

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  • Shapes-tool creating a vector mask every time, cannot seem to fix in CS3?

    - by Bryan
    Every time I create a shape using the shape tool, it places a vector mask on top of this. I don't know how I enabled this but it does not do it on my laptop version, only my desktop. I can seem to disable this problem I am having. Even reinstalling and restoring defaults I cannot seem to stop this. Very frustrating, anyone have a fix for this problem? Thanks in advance!

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  • Crashing when masking an image

    - by shameer
    I am trying to mask an image with a 'mask image". its work fine at first time. but when i try one more time with in the application with same mask image . Application crashed. but when trying with another mask image it works fine. Why this happens? pls help? Console shows ": CGImageMaskCreate: invalid mask bits/component: 4294967295." (UIImage*) maskImage:(UIImage *)image withMask:(UIImage *)maskImage { CGImageRef maskRef = maskImage.CGImage; CGImageRef mask = CGImageMaskCreate(CGImageGetWidth(maskRef), CGImageGetHeight(maskRef), CGImageGetBitsPerComponent(maskRef), CGImageGetBitsPerPixel(maskRef), CGImageGetBytesPerRow(maskRef), CGImageGetDataProvider(maskRef), NULL, false); CGImageRef masked = CGImageCreateWithMask([image CGImage], mask); UIImage *img2=[UIImage imageWithCGImage:masked]; CGImageRelease(maskRef); CGImageRelease(mask); CGImageRelease(masked); return img2; } fun1() { view.image=[self maskImage:image1 withMask:[UIImage imageNamed:@"image2.png"]]; } fun2() { view.image=[self maskImage:image1 withMask:[UIImage imageNamed:@"image2.png"]]; view.image=[self maskImage:image1 withMask:[UIImage imageNamed:@"image3.png"]]; } fun3() { view.image=[self maskImage:image1 withMask:[UIImage imageNamed:@"image2.png"]]; view.image=[self maskImage:image1 withMask:[UIImage imageNamed:@"image2.png"]]; } When calling fun1 and fun2 apllication works fine. Application crashing when calling fun3.

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  • Building simple jQuery plugin, need assistance

    - by kirisu_kun
    Hi there, I'm building my first ever jQuery plugin (it's just a simple experiment). Here's what I have so far: (function($){ $.fn.extend({ auchieFader: function(options) { var defaults = { mask: '', topImg : '', } var options = $.extend(defaults, options); return this.each(function() { var o = options; var obj = $(this); var masker = $(o.mask, obj); masker.hover(function () { $(o.topImg).stop().animate({ "opacity": "0" }, "slow"); }, function () { $(o.topImg).stop().animate({ "opacity": "1" }, "slow"); }); }); } }); })(jQuery); I'm then calling the plugin using: $('.fader').auchieFader({mask: ".mask", topImg: ".top"}); If I then add another request say: $('.fader2').auchieFader({mask: ".mask", topImg: ".top"}); Then no matter what instance of my 2 faders I hover both of them will trigger. I know this is because my mask mask and topImg options have the same class - but how can I modify the plugin to allow for these items to have the same class? I know it's probably something really simple, but I'm still finding my way with jQuery and Javascript in general. Any other tips on improving my code would also be greatly appreciated! Cheers, Chris

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  • Problem with TL-R480T+ and static routes

    - by Globulopolis
    Hi! I've some question about this router. Before starting, some configurations, specified by my provider. Wan1 VPN IP - 192.168.172.84 Mask - 255.255.255.0 Gateway - 192.168.172.253 DNS - 195.110.6.7 Wan2 Dynamic IP DHCP - 168.120.1.34 Mask - 255.255.255.0 Router IP 192.168.1.1 Computer IP 192.168.1.7 Routes: route -p add 192.168.0.0 mask 255.255.0.0 192.168.172.253 route -p add 195.110.6.0 mask 255.255.254.0 192.168.172.253 route -p add 88.135.112.0 mask 255.255.240.0 192.168.172.253 route -p add 178.219.160.0 mask 255.255.240.0 192.168.172.253 For first provider I need to provide a routes. 'Cause router does not support different routes for different WAN interfaces I put them in "Static routes". But when I try to save them I've got an error: Destination IP address can not be set in a same subnet with the WAN or LAN IP address. If I change IP's to local like 192.168.x.x router tell me: Gateway must be set in a same subnet with WAN or LAN IP address. Changing mask on WAN1 interface to 255.255.0.0 doesn't help. Any ideas? PS! Or maybe I'm must email to TP-Link support?

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  • Synergy: Cannot send media keys from Linux to Mac

    - by CraftyThumber
    I have a Linux Synergy server (Si-Linux) serving just one Mac client (Macbook Pro UK) (SiBook-Pro.local). On my Linux server I am using a USB Apple keyboard with the exact layout of the laptops keyboard (the compact UK aluminium keyboard). I would like to send the media keys to the Mac client at all times and I have attempted the following in my synergy.conf: keystroke(AudioPlay) = keystroke(AudioPlay,SiBook-Pro.local) This did not seem to work so I ran both the server and client as foreground processes and with debugging enabled and observed the following: Server Log: DEBUG1: activate actions DEBUG1: hotkey: keyDown(AudioPlay,SiBook-Pro.local) DEBUG1: onKeyDown id=57523 mask=0x0000 button=0x0000 DEBUG1: send key down to "SiBook-Pro.local" id=57523, mask=0x0000, button=0x0000 DEBUG1: deactivate actions DEBUG1: hotkey: keyUp(AudioPlay,SiBook-Pro.local) DEBUG1: onKeyUp id=57523 mask=0x0000 button=0x0000 DEBUG1: send key up to "SiBook-Pro.local" id=57523, mask=0x0000, button=0x0000 Client Log: DEBUG1: recv key down id=0x0000e0b3, mask=0x0000, button=0x0000 DEBUG1: mapKey e0b3 (57523) with mask 0000, start state: 0000 DEBUG1: key e0b3 is not on keyboard DEBUG1: recv key up id=0x0000e0b3, mask=0x0000, button=0x0000 DEBUG1: recv enter, 1279,386 5 2000 As you can see, the client claims the key received is not on keyboard. I don't understand since it is the same key as is on the Macbook's keyboard. I tried to reverse the client-server config to see if I could capture the key being sent if I pressed the Play button on the Macbook but the key doesn't seem to even make it to Synergy. Almost all keyboard presses get logged but the media keys seem to bypass the logs and just execute their function locally. E.g. I press play on the Macbook (with the Macbook as the server) and the key plays music on the Macbook and the key is not logged to the debug log.

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  • How to mask tilde (~) character in C# MVC routing table?

    - by AC
    I'm moving my home-baked web site to MVC and got the trouble with url routing. The site already serves several links that contain tilde (~) character in the path; something like http://.../~files/... http://.../~ws/... and I want each of them are handled by separate controller, like filesController, wsController, so my route table looks like routes.MapRoute( "files", "~files/{*prms}", new { controller = "files", action = "index", prms = "" } ); routes.MapRoute( "ws", "~ws/{*prms}", new { controller = "ws", action = "index", prms = "" } ); ... but when I try to get the result I got the error saying "The route URL cannot start with a '/' or '~' character and it cannot contain a '?' character." As I understand those characters have the special meaning in ASP.net but is it possible to mask them somehow, at least tilde? Should I parse and route requests like this myself? What the best practice to handle urls like this? Thanks!

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  • Can zlib.crc32 or zlib.adler32 be safely used to mask primary keys in URLs?

    - by David Eyk
    In Django Design Patterns, the author recommends using zlib.crc32 to mask primary keys in URLs. After some quick testing, I noticed that crc32 produces negative integers about half the time, which seems undesirable for use in a URL. zlib.adler32 does not appear to produce negatives, but is described as "weaker" than CRC. Is this method (either CRC or Adler-32) safe for usage in a URL as an alternate to a primary key? (i.e. is it collision-safe?) Is the "weaker" Adler-32 a satisfactory alternative for this task? How the heck do you reverse this?! That is, how do you determine the original primary key from the checksum?

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  • Is adding a bit mask to all tables in a database useful?

    - by Tom
    A colleague is adding a bit mask to all our database tables. In theory this is so we can track certain properties of each row across the entire system. For example... Is the row shipped with the system or added by the client once they've started using the system Has the row been deleted from the table (soft deletes) Is the row a default value within a set of rows Is this a good idea? Are there other uses where this approach would be beneficial? My preference is these properties are obviously important, and having a dedicated column for each property is justified to make what is happening clearer to fellow developers.

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  • NSArray in NSArray do not return the image I want

    - by Tibi
    Hi there, I've got a code snippet here that I can't make working. NSUInteger i; //NSMutableArray *textures = [[NSMutableArray alloc] initWithCapacity:kNumTextures]; //NSMutableArray *texturesHighlighted = [[NSMutableArray alloc] initWithCapacity:kNumTextures]; NSMutableArray *textures= [[NSMutableArray alloc] init]; for (i = 1; i <= kNumTextures; i++) { NSString *imageName = [NSString stringWithFormat:@"texture%d.png", i]; NSString *imageNameHighlighted = [NSString stringWithFormat:@"texture%d_select.png", i]; UIImage *image = [UIImage imageNamed:imageName]; UIImage *imageHighlighted = [UIImage imageNamed:imageNameHighlighted]; //NSArray *pics = [[NSArray alloc] initWithObjects:(UIImage)image,(UIImage)imageHighlighted,nil]; NSArray *pics = [NSArray arrayWithObjects:image,imageHighlighted,nil]; [textures addObject:pics]; [pics release]; } //select randomly the position of the picture that will be represented twice on the board NSInteger randomTexture = arc4random()%([textures count]+1); //extract image corresponding to the randomly selected index //remove corresponding pictures from textures array NSArray *coupleTexture = [textures objectAtIndex:randomTexture]; [textures removeObjectAtIndex:randomTexture]; //create the image array containing 1 couple + all other pictures NSMutableArray *texturesBoard = [[NSMutableArray alloc] initWithCapacity:kNumPotatoes]; [texturesBoard addObject:coupleTexture]; [texturesBoard addObject:coupleTexture]; [coupleTexture release]; NSArray *pics = [[NSArray alloc] init]; for (pics in textures) { [texturesBoard addObject:pics]; } [pics release]; //shuffle the textures //[texturesBoard shuffledMutableArray]; //Array with masks NSMutableArray *masks= [[NSMutableArray alloc] init]; for (i = 1; i <= kNumMasks; i++) { NSString *maskName = [NSString stringWithFormat:@"mask%d.png", i]; UIImage *mask = [UIImage imageNamed:maskName]; //NSArray *pics = [[NSArray alloc] initWithObjects:mask,nil]; [masks addObject:mask]; //[pics release]; [maskName release]; [mask release]; } //Now mask all images in texturesBoard NSMutableArray *list = [[NSMutableArray alloc] init]; for (i = 0; i <= kNumMasks-1; i++) { //take on image couple from textures NSArray *imgArray = [texturesBoard objectAtIndex:i]; UIImage *mask = [masks objectAtIndex:i]; //mask it with the mask un the array at corresponding index UIImage *img1 =(UIImage *) [imgArray objectAtIndex:0]; UIImage *img2 =(UIImage *) [imgArray objectAtIndex:1]; UIImage *picsMasked = [self maskImage:(UIImage *)img1 withMask:(UIImage *)mask]; UIImage *picsHighlightedMasked = [self maskImage:(UIImage *)img2 withMask:(UIImage *)mask]; //Init image with highlighted status TapDetectingImageView *imageView = [[TapDetectingImageView alloc] initWithImage:picsMasked imageHighlighted:picsHighlightedMasked]; [list addObject:imageView]; } The problem here is that : img1 and img2, are not images but rather NSArray with multiple entries. Ican't figure why... dos any fresh spirit here could provide me with some clue to fix. maaany thanks.

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  • Handling missing/incomplete data in R--is there function to mask but not remove NAs?

    - by doug
    As you would expect from a DSL aimed at data analysis, R handles missing/incomplete data very well, for instance: Many R functions have an 'na.rm' flag that you can set to 'T' to remove the NAs: mean( c(5,6,12,87,9,NA,43,67), na.rm=T) But if you want to deal with NAs before the function call, you need to do something like this: to remove each 'NA' from a vector: vx = vx[!is.na(a)] to remove each 'NA' from a vector and replace it w/ a '0': ifelse(is.na(vx), 0, vx) to remove entire each row that contains 'NA' from a data frame: dfx = dfx[complete.cases(dfx),] All of these functions permanently remove 'NA' or rows with an 'NA' in them. Sometimes this isn't quite what you want though--making an 'NA'-excised copy of the data frame might be necessary for the next step in the workflow but in subsequent steps you often want those rows back (e.g., to calculate a column-wise statistic for a column that has missing rows caused by a prior call to 'complete cases' yet that column has no 'NA' values in it). to be as clear as possible about what i'm looking for: python/numpy has a class, 'masked array', with a 'mask' method, which lets you conceal--but not remove--NAs during a function call. Is there an analogous function in R?

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  • How would you mask data returned in a Dynamic Data for Entities website?

    - by David Stratton
    I'm doing this in Visual Studio 2008, not 2010, in case there is a relevant difference between the two versions of the Dynamic Data websites. How would I mask data in the automatically generated tables in a Dynamic Data for Entities website? The scenario is we have one table where we want to allow users to ENTER sensitive data, but not VIEW sensitive data, so... (In the list below, I'm using "template" to mean "The web page generated automatically based on the schema and action. I'm sure that's the wrong terminology, but the meaning should be clear.) The "Insert" template should have the field's textbox available for the user to type a value in. The "Edit" template should have the field's textbox blanked out (empty string) regardless of what was in the field in the database in the first place, but the user should be able to type in new data and have it save The "View" template should either have the data for this field masked, or non-visible. The auto-generated table showing the list of records should also have this field masked or non-visible. I can do this easily with standard Web Forms, but I'm having a hard time figuring this out in the Dynamic Data site I'm working on. Masking data is such a common task, I have to believe Microsoft thought of this and provided a way to do it...

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  • Is it possible to rent an IP address to mask the server real IP address?

    - by net-girl
    A customer would like to lease an IP address and point it to a dedicated web server with the intention of "masking" the server's IP address so it would be difficult to tell where the site is hosted. I found a company that leases IP addresses here: http://www.webhostingtalk.com/showthread.php?t=1191688 Is this even possible? Can they rent an IP address from a 3rd party in order to hide the server's IP address? Update: My client will be hosting a government leaks site and is trying to become Raid-Proof similar to what the pirate bay did: http://torrentfreak.com/pirate-bay-moves-to-the-cloud-becomes-raid-proof-121017/ Only that I'm worried about using a reverse proxy because of the latency it could cause having the app servers hosted in one data center and the load balancer/reverse proxy in other and also having to pay twice for bandwidth.

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  • Should I expect ICMP transit traffic to show up when using debug ip packet with a mask on a Cisco IOS router?

    - by David Bullock
    So I am trying to trace an ICMP conversation between 192.168.100.230/32 an EZVPN interface (Virtual-Access 3) and 192.168.100.20 on BVI4. # sh ip access-lists 199 10 permit icmp 192.168.100.0 0.0.0.255 host 192.168.100.20 20 permit icmp host 192.168.100.20 192.168.100.0 0.0.0.255 # sh debug Generic IP: IP packet debugging is on for access list 199 # sh ip route | incl 192.168.100 192.168.100.0/24 is variably subnetted, 2 subnets, 2 masks C 192.168.100.0/24 is directly connected, BVI4 S 192.168.100.230/32 [1/0] via x.x.x.x, Virtual-Access3 # sh log | inc Buff Buffer logging: level debugging, 2145 messages logged, xml disabled, Log Buffer (16384 bytes): OK, so from my EZVPN client with IP address 192.168.100.230, I ping 192.168.100.20. I know the packet reaches the router across the VPN tunnel, because: policy exists on zp vpn-to-in Zone-pair: vpn-to-in Service-policy inspect : acl-based-policy Class-map: desired-traffic (match-all) Match: access-group name my-acl Inspect Number of Half-open Sessions = 1 Half-open Sessions Session 84DB9D60 (192.168.100.230:8)=>(192.168.100.20:0) icmp SIS_OPENING Created 00:00:05, Last heard 00:00:00 ECHO request Bytes sent (initiator:responder) [64:0] Class-map: class-default (match-any) Match: any Drop 176 packets, 12961 bytes But I get no debug log, and the debugging ACL hasn't matched: # sh log | inc IP: # # sh ip access-lists 198 Extended IP access list 198 10 permit icmp 192.168.100.0 0.0.0.255 host 192.168.100.20 20 permit icmp host 192.168.100.20 192.168.100.0 0.0.0.255 Am I going crazy, or should I not expect to see this debug log? Thanks!

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  • how to round_corner a logo without leaving white background(transparent?) with it using pil?

    - by bdictator
    I got a square logo and I need to round_corner it, searched for a while and got the follow code "working": def round_corner_jpg(image, radius): """generate round corner for image""" mask = Image.new('RGB', image.size) #mask = Image.new('RGB', (image.size[0] - radius, image.size[1] - radius)) #mask = Image.new('L', image.size, 255) draw = aggdraw.Draw(mask) brush = aggdraw.Brush('black') width, height = mask.size draw.rectangle((0,0,width,height), aggdraw.Brush('')) #upper-left corner draw.pieslice((0,0,radius*2, radius*2), 90, 180, None, brush) #upper-right corner draw.pieslice((width - radius*2, 0, width, radius*2), 0, 90, None, brush) #bottom-left corner draw.pieslice((0, height - radius * 2, radius*2, height),180, 270, None, brush) #bottom-right corner draw.pieslice((width - radius * 2, height - radius * 2, width, height), 270, 360, None, brush) #center rectangle draw.rectangle((radius, radius, width - radius, height - radius), brush) #four edge rectangle draw.rectangle((radius, 0, width - radius, radius), brush) draw.rectangle((0, radius, radius, height-radius), brush) draw.rectangle((radius, height-radius, width-radius, height), brush) draw.rectangle((width-radius, radius, width, height-radius), brush) draw.flush() del draw return ImageChops.add(mask, image) then I saved the returned image object,however it has white background in it?how can i get rid of the white background? Thanks in advance~

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  • Finding N contiguous zero bits in an integer to the left of the MSB position of another integer

    - by James Morris
    The problem is: given an integer val1 find the position of the highest bit set (Most Significant Bit) then, given a second integer val2 find a contiguous region of unset bits, with the minimum number of zero bits given by width to the left of the position (ie, in the higher bits). Here is the C code for my solution: typedef unsigned int t; unsigned const t_bits = sizeof(t) * CHAR_BIT; _Bool test_fit_within_left_of_msb( unsigned width, t val1, t val2, unsigned* offset_result) { unsigned offbit = 0; unsigned msb = 0; t mask; t b; while(val1 >>= 1) ++msb; while(offbit + width < t_bits - msb) { mask = (((t)1 << width) - 1) << (t_bits - width - offbit); b = val2 & mask; if (!b) { *offset_result = offbit; return true; } if (offbit++) /* this conditional bothers me! */ b <<= offbit - 1; while(b <<= 1) offbit++; } return false; } Aside from faster ways of finding the MSB of the first integer, the commented test for a zero offbit seems a bit extraneous, but necessary to skip the highest bit of type t if it is set. I have also implemented similar algorithms but working to the right of the MSB of the first number, so they don't require this seemingly extra condition. How can I get rid of this extra condition, or even, are there far more optimal solutions? Edit: Some background not strictly required. The offset result is a count of bits from the high bit, not from the low bit as maybe expected. This will be part of a wider algorithm which scans a 2D array for a 2D area of zero bits. Here, for testing, the algorithm has been simplified. val1 represents the first integer which does not have all bits set found in a row of the 2D array. From this the 2D version would scan down which is what val2 represents. Here's some output showing success and failure: t_bits:32 t_high: 10000000000000000000000000000000 ( 2147483648 ) --------- ----------------------------------- *** fit within left of msb test *** ----------------------------------- val1: 00000000000000000000000010000000 ( 128 ) val2: 01000001000100000000100100001001 ( 1091569929 ) msb: 7 offbit:0 + width: 8 = 8 mask: 11111111000000000000000000000000 ( 4278190080 ) b: 01000001000000000000000000000000 ( 1090519040 ) offbit:8 + width: 8 = 16 mask: 00000000111111110000000000000000 ( 16711680 ) b: 00000000000100000000000000000000 ( 1048576 ) offbit:12 + width: 8 = 20 mask: 00000000000011111111000000000000 ( 1044480 ) b: 00000000000000000000000000000000 ( 0 ) offbit:12 iters:10 ***** found room for width:8 at offset: 12 ***** ----------------------------------- *** fit within left of msb test *** ----------------------------------- val1: 00000000000000000000000001000000 ( 64 ) val2: 00010000000000001000010001000001 ( 268469313 ) msb: 6 offbit:0 + width: 13 = 13 mask: 11111111111110000000000000000000 ( 4294443008 ) b: 00010000000000000000000000000000 ( 268435456 ) offbit:4 + width: 13 = 17 mask: 00001111111111111000000000000000 ( 268402688 ) b: 00000000000000001000000000000000 ( 32768 ) ***** mask: 00001111111111111000000000000000 ( 268402688 ) offbit:17 iters:15 ***** no room found for width:13 ***** (iters is the count of iterations of the inner while loop)

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  • Dhcpd Daemon is trying to lease itself?

    - by tommieb75
    I have a Slackware Linux 13.0 box with two interfaces, eth0 and eth1. I have set this box up to be on the 192.168.1.0/24 network, with subnet mask of 255.255.255.0. I am trying to run a dhcpd server on this box to service two interfaces above, so I subnetted the 192.168.1.0/24 network into two subnets. For eth0 192.168.1.1, subnet mask 255.255.255.128, broadcast mask 192.168.1.127. For eth1 192.168.1.129, subnet mask 255.255.255.128, broadcast mask 192.168.1.255. Both the interfaces are assigned manually. eth0 Link encap:Ethernet HWaddr 00:00:00:00:00:00 inet addr:192.168.1.1 Bcast:192.168.1.127 Mask:255.255.255.128 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:39 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:1404 (1.3 KiB) Interrupt:11 Base address:0x8000 Memory:faffc000-faffcfff eth1 Link encap:Ethernet HWaddr 00:00:00:00:00:00 inet addr:192.168.1.128 Bcast:192.168.1.255 Mask:255.255.255.128 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:10003 errors:0 dropped:0 overruns:0 frame:0 TX packets:13286 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:1589229 (1.5 MiB) TX bytes:9900005 (9.4 MiB) Interrupt:11 Here is the dhcpd.conf set up authoritative; ddns-update-style interim; ignore client-updates; subnet 192.168.1.0 netmask 255.255.255.128 { range 192.168.1.2 192.168.1.126; default-lease-time 86400; max-lease-time 86400; option routers 192.168.1.1; option ip-forwarding off; option domain-name-servers 208.67.222.222, 208.67.220.220; option broadcast-address 192.168.1.127; option subnet-mask 255.255.255.128; } subnet 192.168.1.128 netmask 255.255.255.128 { range 192.168.1.129 192.168.1.254; default-lease-time 86400; max-lease-time 86400; option routers 192.168.1.1; option ip-forwarding off; option domain-name-servers 208.67.222.222, 208.67.220.220; option broadcast-address 192.168.1.255; option subnet-mask 255.255.255.128; } This is what is showing in the log Apr 10 18:09:58 inspiron8600 dhcpd: DHCPDISCOVER from 00:00:00:00:00:00 (inspiron8600) via eth1 Apr 10 18:09:58 inspiron8600 dhcpd: DHCPOFFER on 192.168.1.131 to 00:00:00:00:00:00 (inspiron8600) via eth1 Apr 10 18:10:01 inspiron8600 dhcpcd[3832]: eth1: adding IP address 169.254.153.6/16 This is happening spuriously, and the log gets filled up with nonsense..so my question is this: How do I stop this from happening? And why would it be trying to give itself a lease? I am sure I have missed something but cannot see it and would appreciate a pair of eyes from the community to spot the obvious flaw!

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  • DD-WRT RIP2 Router mode configuration

    - by Eduardo
    Can anybody tell me why my wireless router only redirects traffic to ADSL modem when it is on Gateway mode? These are the configurations when it is on RIP2 Router mode: ADSL Modem: ------------ LAN IP: 10.1.1.1 Subnet mask: 255.0.0.0 RIP v2 enabled in both directions Route: destination: 192.168.1.0 Subnet mask: 255.255.255.0 Gateway: 10.1.1.2 Wireless Router (DD-WRT) ------------------------ WAN IP: 10.1.1.2 WAN Subnet mask: 255.0.0.0 LAN IP: 192.168.1.1 LAN Subnet mask: 255.255.255.0 Operating mode: RIP2 Router Static Route: Destination LAN NET: 10.0.0.0 Subnet Mask: 255.0.0.0 Gateway: 10.1.1.1 Interface: LAN & WLAN

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  • Samba smb.conf read only and read/write accounts

    - by Pieter
    Below you can see my smb.conf, pieter is my admin user read/write on the shares works good with that account. Then I have a leecher account that has been added with smbpasswd -a leecher to the smb users, it is set up so this user only has read access to the shares. This works on MegaSam and on Thumbnails but not on my other drives, leecher does not get any access on the other shares. [global] security = user [MegaSam] comment = MegaSam path = /media/MegaSam browsable = yes guest ok = no read list = leecher write list = pieter create mask = 0755 [SilentBob] comment = SilentBob path = /media/SilentBob browsable = yes guest ok = no read list = leecher write list = pieter create mask = 0755 [Thumbnails] comment = Thumbnails path = /media/Thumbnails browsable = yes guest ok = no read list = leecher write list = pieter create mask = 0755 [Downloads] comment = Downloads path = /media/Downloads browsable = yes guest ok = no read list = leecher write list = pieter create mask = 0755

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  • PTLQueue : a scalable bounded-capacity MPMC queue

    - by Dave
    Title: Fast concurrent MPMC queue -- I've used the following concurrent queue algorithm enough that it warrants a blog entry. I'll sketch out the design of a fast and scalable multiple-producer multiple-consumer (MPSC) concurrent queue called PTLQueue. The queue has bounded capacity and is implemented via a circular array. Bounded capacity can be a useful property if there's a mismatch between producer rates and consumer rates where an unbounded queue might otherwise result in excessive memory consumption by virtue of the container nodes that -- in some queue implementations -- are used to hold values. A bounded-capacity queue can provide flow control between components. Beware, however, that bounded collections can also result in resource deadlock if abused. The put() and take() operators are partial and wait for the collection to become non-full or non-empty, respectively. Put() and take() do not allocate memory, and are not vulnerable to the ABA pathologies. The PTLQueue algorithm can be implemented equally well in C/C++ and Java. Partial operators are often more convenient than total methods. In many use cases if the preconditions aren't met, there's nothing else useful the thread can do, so it may as well wait via a partial method. An exception is in the case of work-stealing queues where a thief might scan a set of queues from which it could potentially steal. Total methods return ASAP with a success-failure indication. (It's tempting to describe a queue or API as blocking or non-blocking instead of partial or total, but non-blocking is already an overloaded concurrency term. Perhaps waiting/non-waiting or patient/impatient might be better terms). It's also trivial to construct partial operators by busy-waiting via total operators, but such constructs may be less efficient than an operator explicitly and intentionally designed to wait. A PTLQueue instance contains an array of slots, where each slot has volatile Turn and MailBox fields. The array has power-of-two length allowing mod/div operations to be replaced by masking. We assume sensible padding and alignment to reduce the impact of false sharing. (On x86 I recommend 128-byte alignment and padding because of the adjacent-sector prefetch facility). Each queue also has PutCursor and TakeCursor cursor variables, each of which should be sequestered as the sole occupant of a cache line or sector. You can opt to use 64-bit integers if concerned about wrap-around aliasing in the cursor variables. Put(null) is considered illegal, but the caller or implementation can easily check for and convert null to a distinguished non-null proxy value if null happens to be a value you'd like to pass. Take() will accordingly convert the proxy value back to null. An advantage of PTLQueue is that you can use atomic fetch-and-increment for the partial methods. We initialize each slot at index I with (Turn=I, MailBox=null). Both cursors are initially 0. All shared variables are considered "volatile" and atomics such as CAS and AtomicFetchAndIncrement are presumed to have bidirectional fence semantics. Finally T is the templated type. I've sketched out a total tryTake() method below that allows the caller to poll the queue. tryPut() has an analogous construction. Zebra stripping : alternating row colors for nice-looking code listings. See also google code "prettify" : https://code.google.com/p/google-code-prettify/ Prettify is a javascript module that yields the HTML/CSS/JS equivalent of pretty-print. -- pre:nth-child(odd) { background-color:#ff0000; } pre:nth-child(even) { background-color:#0000ff; } border-left: 11px solid #ccc; margin: 1.7em 0 1.7em 0.3em; background-color:#BFB; font-size:12px; line-height:65%; " // PTLQueue : Put(v) : // producer : partial method - waits as necessary assert v != null assert Mask = 1 && (Mask & (Mask+1)) == 0 // Document invariants // doorway step // Obtain a sequence number -- ticket // As a practical concern the ticket value is temporally unique // The ticket also identifies and selects a slot auto tkt = AtomicFetchIncrement (&PutCursor, 1) slot * s = &Slots[tkt & Mask] // waiting phase : // wait for slot's generation to match the tkt value assigned to this put() invocation. // The "generation" is implicitly encoded as the upper bits in the cursor // above those used to specify the index : tkt div (Mask+1) // The generation serves as an epoch number to identify a cohort of threads // accessing disjoint slots while s-Turn != tkt : Pause assert s-MailBox == null s-MailBox = v // deposit and pass message Take() : // consumer : partial method - waits as necessary auto tkt = AtomicFetchIncrement (&TakeCursor,1) slot * s = &Slots[tkt & Mask] // 2-stage waiting : // First wait for turn for our generation // Acquire exclusive "take" access to slot's MailBox field // Then wait for the slot to become occupied while s-Turn != tkt : Pause // Concurrency in this section of code is now reduced to just 1 producer thread // vs 1 consumer thread. // For a given queue and slot, there will be most one Take() operation running // in this section. // Consumer waits for producer to arrive and make slot non-empty // Extract message; clear mailbox; advance Turn indicator // We have an obvious happens-before relation : // Put(m) happens-before corresponding Take() that returns that same "m" for T v = s-MailBox if v != null : s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 // unlock slot to admit next producer and consumer return v Pause tryTake() : // total method - returns ASAP with failure indication for auto tkt = TakeCursor slot * s = &Slots[tkt & Mask] if s-Turn != tkt : return null T v = s-MailBox // presumptive return value if v == null : return null // ratify tkt and v values and commit by advancing cursor if CAS (&TakeCursor, tkt, tkt+1) != tkt : continue s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 return v The basic idea derives from the Partitioned Ticket Lock "PTL" (US20120240126-A1) and the MultiLane Concurrent Bag (US8689237). The latter is essentially a circular ring-buffer where the elements themselves are queues or concurrent collections. You can think of the PTLQueue as a partitioned ticket lock "PTL" augmented to pass values from lock to unlock via the slots. Alternatively, you could conceptualize of PTLQueue as a degenerate MultiLane bag where each slot or "lane" consists of a simple single-word MailBox instead of a general queue. Each lane in PTLQueue also has a private Turn field which acts like the Turn (Grant) variables found in PTL. Turn enforces strict FIFO ordering and restricts concurrency on the slot mailbox field to at most one simultaneous put() and take() operation. PTL uses a single "ticket" variable and per-slot Turn (grant) fields while MultiLane has distinct PutCursor and TakeCursor cursors and abstract per-slot sub-queues. Both PTL and MultiLane advance their cursor and ticket variables with atomic fetch-and-increment. PTLQueue borrows from both PTL and MultiLane and has distinct put and take cursors and per-slot Turn fields. Instead of a per-slot queues, PTLQueue uses a simple single-word MailBox field. PutCursor and TakeCursor act like a pair of ticket locks, conferring "put" and "take" access to a given slot. PutCursor, for instance, assigns an incoming put() request to a slot and serves as a PTL "Ticket" to acquire "put" permission to that slot's MailBox field. To better explain the operation of PTLQueue we deconstruct the operation of put() and take() as follows. Put() first increments PutCursor obtaining a new unique ticket. That ticket value also identifies a slot. Put() next waits for that slot's Turn field to match that ticket value. This is tantamount to using a PTL to acquire "put" permission on the slot's MailBox field. Finally, having obtained exclusive "put" permission on the slot, put() stores the message value into the slot's MailBox. Take() similarly advances TakeCursor, identifying a slot, and then acquires and secures "take" permission on a slot by waiting for Turn. Take() then waits for the slot's MailBox to become non-empty, extracts the message, and clears MailBox. Finally, take() advances the slot's Turn field, which releases both "put" and "take" access to the slot's MailBox. Note the asymmetry : put() acquires "put" access to the slot, but take() releases that lock. At any given time, for a given slot in a PTLQueue, at most one thread has "put" access and at most one thread has "take" access. This restricts concurrency from general MPMC to 1-vs-1. We have 2 ticket locks -- one for put() and one for take() -- each with its own "ticket" variable in the form of the corresponding cursor, but they share a single "Grant" egress variable in the form of the slot's Turn variable. Advancing the PutCursor, for instance, serves two purposes. First, we obtain a unique ticket which identifies a slot. Second, incrementing the cursor is the doorway protocol step to acquire the per-slot mutual exclusion "put" lock. The cursors and operations to increment those cursors serve double-duty : slot-selection and ticket assignment for locking the slot's MailBox field. At any given time a slot MailBox field can be in one of the following states: empty with no pending operations -- neutral state; empty with one or more waiting take() operations pending -- deficit; occupied with no pending operations; occupied with one or more waiting put() operations -- surplus; empty with a pending put() or pending put() and take() operations -- transitional; or occupied with a pending take() or pending put() and take() operations -- transitional. The partial put() and take() operators can be implemented with an atomic fetch-and-increment operation, which may confer a performance advantage over a CAS-based loop. In addition we have independent PutCursor and TakeCursor cursors. Critically, a put() operation modifies PutCursor but does not access the TakeCursor and a take() operation modifies the TakeCursor cursor but does not access the PutCursor. This acts to reduce coherence traffic relative to some other queue designs. It's worth noting that slow threads or obstruction in one slot (or "lane") does not impede or obstruct operations in other slots -- this gives us some degree of obstruction isolation. PTLQueue is not lock-free, however. The implementation above is expressed with polite busy-waiting (Pause) but it's trivial to implement per-slot parking and unparking to deschedule waiting threads. It's also easy to convert the queue to a more general deque by replacing the PutCursor and TakeCursor cursors with Left/Front and Right/Back cursors that can move either direction. Specifically, to push and pop from the "left" side of the deque we would decrement and increment the Left cursor, respectively, and to push and pop from the "right" side of the deque we would increment and decrement the Right cursor, respectively. We used a variation of PTLQueue for message passing in our recent OPODIS 2013 paper. ul { list-style:none; padding-left:0; padding:0; margin:0; margin-left:0; } ul#myTagID { padding: 0px; margin: 0px; list-style:none; margin-left:0;} -- -- There's quite a bit of related literature in this area. I'll call out a few relevant references: Wilson's NYU Courant Institute UltraComputer dissertation from 1988 is classic and the canonical starting point : Operating System Data Structures for Shared-Memory MIMD Machines with Fetch-and-Add. Regarding provenance and priority, I think PTLQueue or queues effectively equivalent to PTLQueue have been independently rediscovered a number of times. See CB-Queue and BNPBV, below, for instance. But Wilson's dissertation anticipates the basic idea and seems to predate all the others. Gottlieb et al : Basic Techniques for the Efficient Coordination of Very Large Numbers of Cooperating Sequential Processors Orozco et al : CB-Queue in Toward high-throughput algorithms on many-core architectures which appeared in TACO 2012. Meneghin et al : BNPVB family in Performance evaluation of inter-thread communication mechanisms on multicore/multithreaded architecture Dmitry Vyukov : bounded MPMC queue (highly recommended) Alex Otenko : US8607249 (highly related). John Mellor-Crummey : Concurrent queues: Practical fetch-and-phi algorithms. Technical Report 229, Department of Computer Science, University of Rochester Thomasson : FIFO Distributed Bakery Algorithm (very similar to PTLQueue). Scott and Scherer : Dual Data Structures I'll propose an optimization left as an exercise for the reader. Say we wanted to reduce memory usage by eliminating inter-slot padding. Such padding is usually "dark" memory and otherwise unused and wasted. But eliminating the padding leaves us at risk of increased false sharing. Furthermore lets say it was usually the case that the PutCursor and TakeCursor were numerically close to each other. (That's true in some use cases). We might still reduce false sharing by incrementing the cursors by some value other than 1 that is not trivially small and is coprime with the number of slots. Alternatively, we might increment the cursor by one and mask as usual, resulting in a logical index. We then use that logical index value to index into a permutation table, yielding an effective index for use in the slot array. The permutation table would be constructed so that nearby logical indices would map to more distant effective indices. (Open question: what should that permutation look like? Possibly some perversion of a Gray code or De Bruijn sequence might be suitable). As an aside, say we need to busy-wait for some condition as follows : "while C == 0 : Pause". Lets say that C is usually non-zero, so we typically don't wait. But when C happens to be 0 we'll have to spin for some period, possibly brief. We can arrange for the code to be more machine-friendly with respect to the branch predictors by transforming the loop into : "if C == 0 : for { Pause; if C != 0 : break; }". Critically, we want to restructure the loop so there's one branch that controls entry and another that controls loop exit. A concern is that your compiler or JIT might be clever enough to transform this back to "while C == 0 : Pause". You can sometimes avoid this by inserting a call to a some type of very cheap "opaque" method that the compiler can't elide or reorder. On Solaris, for instance, you could use :"if C == 0 : { gethrtime(); for { Pause; if C != 0 : break; }}". It's worth noting the obvious duality between locks and queues. If you have strict FIFO lock implementation with local spinning and succession by direct handoff such as MCS or CLH,then you can usually transform that lock into a queue. Hidden commentary and annotations - invisible : * And of course there's a well-known duality between queues and locks, but I'll leave that topic for another blog post. * Compare and contrast : PTLQ vs PTL and MultiLane * Equivalent : Turn; seq; sequence; pos; position; ticket * Put = Lock; Deposit Take = identify and reserve slot; wait; extract & clear; unlock * conceptualize : Distinct PutLock and TakeLock implemented as ticket lock or PTL Distinct arrival cursors but share per-slot "Turn" variable provides exclusive role-based access to slot's mailbox field put() acquires exclusive access to a slot for purposes of "deposit" assigns slot round-robin and then acquires deposit access rights/perms to that slot take() acquires exclusive access to slot for purposes of "withdrawal" assigns slot round-robin and then acquires withdrawal access rights/perms to that slot At any given time, only one thread can have withdrawal access to a slot at any given time, only one thread can have deposit access to a slot Permissible for T1 to have deposit access and T2 to simultaneously have withdrawal access * round-robin for the purposes of; role-based; access mode; access role mailslot; mailbox; allocate/assign/identify slot rights; permission; license; access permission; * PTL/Ticket hybrid Asymmetric usage ; owner oblivious lock-unlock pairing K-exclusion add Grant cursor pass message m from lock to unlock via Slots[] array Cursor performs 2 functions : + PTL ticket + Assigns request to slot in round-robin fashion Deconstruct protocol : explication put() : allocate slot in round-robin fashion acquire PTL for "put" access store message into slot associated with PTL index take() : Acquire PTL for "take" access // doorway step seq = fetchAdd (&Grant, 1) s = &Slots[seq & Mask] // waiting phase while s-Turn != seq : pause Extract : wait for s-mailbox to be full v = s-mailbox s-mailbox = null Release PTL for both "put" and "take" access s-Turn = seq + Mask + 1 * Slot round-robin assignment and lock "doorway" protocol leverage the same cursor and FetchAdd operation on that cursor FetchAdd (&Cursor,1) + round-robin slot assignment and dispersal + PTL/ticket lock "doorway" step waiting phase is via "Turn" field in slot * PTLQueue uses 2 cursors -- put and take. Acquire "put" access to slot via PTL-like lock Acquire "take" access to slot via PTL-like lock 2 locks : put and take -- at most one thread can access slot's mailbox Both locks use same "turn" field Like multilane : 2 cursors : put and take slot is simple 1-capacity mailbox instead of queue Borrow per-slot turn/grant from PTL Provides strict FIFO Lock slot : put-vs-put take-vs-take at most one put accesses slot at any one time at most one put accesses take at any one time reduction to 1-vs-1 instead of N-vs-M concurrency Per slot locks for put/take Release put/take by advancing turn * is instrumental in ... * P-V Semaphore vs lock vs K-exclusion * See also : FastQueues-excerpt.java dice-etc/queue-mpmc-bounded-blocking-circular-xadd/ * PTLQueue is the same as PTLQB - identical * Expedient return; ASAP; prompt; immediately * Lamport's Bakery algorithm : doorway step then waiting phase Threads arriving at doorway obtain a unique ticket number Threads enter in ticket order * In the terminology of Reed and Kanodia a ticket lock corresponds to the busy-wait implementation of a semaphore using an eventcount and a sequencer It can also be thought of as an optimization of Lamport's bakery lock was designed for fault-tolerance rather than performance Instead of spinning on the release counter, processors using a bakery lock repeatedly examine the tickets of their peers --

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  • Internet is not working in base machine

    - by surendar
    I have a Ubuntu desktop. I am running a virtual windows machine using virtual box. Few days before Internet is not working in Ubuntu but it is working in the virtual machine. Even the samba shares are also accessible. I don't know why internet is not working in the base machine. I have tried to ping google.com, but it returns Ubuntu@desktop:~$ ping google.com ping: unknown host google.com ifconfig command's output Ubuntu@desktop:~$ ifconfig eth0 Link encap:Ethernet HWaddr 00:27:0e:1b:86:2a inet addr:192.168.1.7 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::227:eff:fe1b:862a/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:38221 errors:0 dropped:0 overruns:0 frame:0 TX packets:28161 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:39144616 (39.1 MB) TX bytes:6143919 (6.1 MB) Interrupt:27 Base address:0x2000 eth0:0 Link encap:Ethernet HWaddr 00:27:0e:1b:86:2a inet addr:192.168.2.7 Bcast:192.168.2.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 Interrupt:27 Base address:0x2000 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:14944 errors:0 dropped:0 overruns:0 frame:0 TX packets:14944 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:1735451 (1.7 MB) TX bytes:1735451 (1.7 MB) vmnet1 Link encap:Ethernet HWaddr 00:50:56:c0:00:01 inet addr:192.168.243.1 Bcast:192.168.243.255 Mask:255.255.255.0 inet6 addr: fe80::250:56ff:fec0:1/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:77 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) vmnet8 Link encap:Ethernet HWaddr 00:50:56:c0:00:08 inet addr:172.16.162.1 Bcast:172.16.162.255 Mask:255.255.255.0 inet6 addr: fe80::250:56ff:fec0:8/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:78 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)

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  • What collision detection approach for top down car game?

    - by nathan
    I have a quite advanced top down car game and i use masks to detect collisions. I have the actual designed track (what the player see) with fancy graphics etc. and two other pictures i use as mask for my detection collisions. Each mask has only two colors, white and black and i check each frame if a pixel of the car collide with a black pixel of the masks. This approach works of course but it's not really flexible. Whenever i want to change the look of a track, i have to redraw the mask and it's a real pain. What is the general approach for this kind of game? How can i improve the flexibility of such a mask based approach?

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