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• How to pass an argument to a Windows Scheduled Task with spaces in it

  - by Rodney

  I need to set up a Windows Scheduled Task. It accepts 1 parameter/argument which is a path and can contain spaces. My Scheduled task does not work - it "breaks" the parameter up at the first space. If I run it in the Command Prompt I can just wrap the argument in " " and it works fine, however, this does not work in the Scheduled Task UI. e.g. C:\Program Files\xyz\FTP File Transfer\FTPFileTransferTask.exe "C:\Program Files\xyz\The Interface\Folder Path" I have tried wrapping the argument with " " ' ' [ ] () and have tried filling in the spaces with %20, ~1 etc. with no luck. I know of one solution to make a bat file and use " " around my argument but I don't want to add more complexity. I tried it on Windows 7 and Windows 2008 Server and both failed. There seems to be no discussions on this?

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• Configuring BIND to use VM's DNS for specific domain

  - by Srirangan

  I work on a project for which I use an Ubuntu server vm on an Ubuntu host. The VM runs all the services / webapps through haproxy and nginx and serves it on the domain (xyz.com). I manually modify my resolv.conf to use the VMs IP address as the nameserver and I can run my app on the host browser. The problem is I am modifying an auto-generated file (resolv.conf) and I need to do it each time. Is there a smart way to say: -- are you accessing xyz.com? -- if yes use VM's DNS server, else use the hosts

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• Gmail flagging emails as spam despite SPF being enabled and working perfectly

  - by Asif

  I have a website where people can recommend contents to their friends using their email. The issue is that emails are being flagged as spam whereas if I do the same from my development machine things are working out fine. I have enabled SPF and it is perfect. When sending through website, the email appears as this in Gmail Inbox: From [email protected] to [email protected]. When I send it from my development machine it appears as : From xyz.com via mywebsite.com to [email protected] mailed by mywebsite.com and this is exactly how I envisioned it. From what little I could figure out by looking at the source of emails in Gmail is that when sending from my development machine Gmail correctly recognizes my domain as mywebsite.com for which SPF is enabled and hence it treats it as genuine email. Whereas Gmail recognizes my domain as [email protected] when sent through the website. Can someone tell me why it does so? Any help would be really appreciated.

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• 2 sited hosted in NGINX with separate SSL certs. IE8 posting invalid when starting at one site going to the other

  - by Dave Johnsen

  If users with IE8 go directly to www.xyz.com, SSL cert is fine. Users going directly to www.zyx.com have no issues with cert. If users start at one site and go to the other, they get invalid cert with xyz being used on zyx which should not be happening. Reading the forums NGINX has SNI enabled and I have the correct version of OpenSSL to be able to handle multiple certs. IE8 seems to be the issue but these are customer facing sites. Is there a fix to make NGINX work for the customers experiencing the issue.

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• Google Apps - Can I configure a wildcard MX record and and catch all emai address for a domain

  - by Rohit

  I am using Google Apps Premier Edition. I want to create a disposable email address service and I want to catch all emails for a domain. This means that I should be able to catch all mails sent to an arbitrary userid and/or arbitrary domain and store them into a single Google Apps account. For example, in a single account I want to get all mails sent to: 1) [email protected] 2) [email protected] without requiring to do any extra configuration in Google Apps for abc or xyz. My app will download mails from this account and process accordingly. I have figured out that I could do (1) by specifying a catch all email address. Is the combination of both (1) and (2) possible?

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• Mount encrypted hfs in ubuntu

  - by pagid

  I try to mount an encrypted hfs+ partition in ubuntu. An older post described quite good how to do it, but lacks the information how to use encrypted partitions. What I found so far is: # install required packages sudo apt-get install hfsprogs hfsutils hfsplus loop-aes-utils # try to mount it mount -t hfsplus -o encryption=aes-256 /dev/xyz /mount/xyz But once I run this I get the following error: Error: Password must be at least 20 characters. So I tried to type it in twice, but that results in this: ioctl: LOOP_SET_STATUS: Invalid argument, requested cipher or key (256 bits) not supported by kernel Any suggestions? Thx Edit: One thing I'm not sure about is whether I use the right password. My assumption is that it is my default one for these situations. But I'm not sure whether Max OSX choose another password (internally) for that.

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• Convert shell logs (incl. escape characters) to HTML?

  - by dehmann

  Is there tool or a regexp that can convert shell escape characters to HTML code? As an example, here is a logfile from GNU screen: ^MESC[K$ ^MESC[K$ exit Executing .bashrc ESC[00;31;31mserver.xyz.com: ESC[00;34;34m~ which I would like to convert to something like this: $ exit Executing .bashrc <font color=red>server.xyz.com</font>: <font color=blue>~</font> and send as HTML e-mail to an e-mail address, to archive my work. Here is a related question, which shows how to convert it to regular text, but it would be nice to convert to HTML and not just throw the escape characters away.

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• wildcard host name bindings for multiple subdomains in multiple sites on IIS7 with a single IP address

  - by orca

  Situation: I have a single windows 2008 server with a single public IP address. I have multiple domains with wildcard A records pointing to the single IP address. I need each domain to be hosted by a different web site. (i.e. www.domain1.com by site domain1site) I need domain1.com to act like www.domain1.com I need each site to be able to have multiple subdomains (i.e. www.domain1.com, abc.domain1.com, xyz.domain1.com) Not relevant yet here it goes, I plan to handle each subdomain by a different application hosted in the same site (i.e. application /xyz in domain1site) However I found out that IIS7 does not support creating web sites with wildcard host name binding and setting it without any subdomain (i.e. domain1.com) does not work, even for www.domain1.com. Is there a simple solution? Does any IIS Extension like Application Request Routing provide such capability?

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• Reverse lookup of inode/file from offset in raw device on linux and ext3/4?

  - by lilinjn

  In linux, given an offset into a raw disk device, is it possible to map back to an partition + inode? For example, suppose I know that string "xyz" is contained at byte offset 1000000 on /dev/sda: (e.g. xxd -l 100 -s 1000000 /dev/sda shows a dump that begins with "xyz") 1) How do I figure out which partition (if any) offset 1000000 is located in?(I imagine this is easy, but am including it for completeness) 2) Assuming the offset is located in a partition, how do I go about finding which inode it belongs to (or determine that it is part of free space) ? Presumably this is filesystem specific, in which case does any one know how to do this for ext4 and ext3?

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• redirect to rootdomain after the first slash in url

  - by user142397

  I want to redirect this: http://www.site.com/xyz To http://www.site.com/ Basically i want to redirect to the root domain if a user types anything else after the first slash of my domain name like /xyz or anything else should be redirected or rewritten as the root URL in the browser. Can anybody help? Thanks for your help! (* This should be only for the first time like when a new user comes to visit my page, because once the page loads for the first time i do not want any re directions as i have different directories, and related webpages. Otherwise my visitor will only see landing page. )

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• Windows Services don't automatically start after reboot?

  - by James Crowley

  We've got some Windows services written in .NET. They start fine manually within the services mmc, but despite being set to Automatic, they never start when powering on (or rebooting) the machine. Update In the event log, instead of seeing "xyz started", alongside all the other services starting, I just see "The xyz service entered the stopped state." and a seperate error that says "A timeout (30000 milliseconds) was reached while waiting for a transaction response from the slsvc service.". If I manually start them, then I get a normal in the event log as expected, and all is fine - until the next Windows Update patch which forces a reboot and all the services are off again. Any ideas? I've tried setting them to Delayed Start with no apparent difference.

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• proxy pass redirection

  - by zam

  I am struggling with a redirection rule. I am now running my Redmine in webrick in port 3000 and proxy-pass it. The URL of my Redmine is xyz.example.com. I also want to redirect the Redmine using the URL: abc.example.com. I added the server alias but no redirection taking place. Here is my configuration: <VirtualHost *:80> ServerName xyz.example.com ServerAlias abc.examle.com ProxyPass / h://local:3000/ ProxyPassReverse / h://local:3000/ </VirtualHost>

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• OpenGL ES Shader help (Blending)

  - by Chris

  Earlier I required assistance getting to grips with how to retain the alpha channel of a transparent texture in my colourised texture shader program. Whilst playing with that first version of my program (before obtaining the solution to my first requirement), I managed to enable transparency for the whole texture (effectively blending via GLSL), and I quite liked this, and I would now like to know if and how it is possible to retain this blending effect, on top of the existing output without affecting the original alpha channel - as I don't know how to input this transparency via the parameter that is already being provided with the textures alpha channel. A basic example of the blending program I am referring to (minus any other functionality) is as follows... varying vec2 texCoord; uniform sampler2D texSampler; void main() { gl_FragColor = vec4(texture2D(texSampler,texCoord).xyz,0.5); } Where 0.5 is the transparency (blending effect) of the whole texture. This is the current version of my program, which provides the ability to colour a texture according the colour parameter passed to the program, and retains the alpha channel of the original texture. varying vec2 texCoord; uniform sampler2D texSampler; uniform vec3 colour; void main() { gl_FragColor = vec4(colour,1) * vec4(texture2D(texSampler,texCoord).xyz,texture2D(texSampler,texCoord).w); } I need to know if it is possible to apply transparency on top this program, without affecting the original alpha channel which I have already preserved. I hope this makes enough sense, I am sure it is possible, and if so I should imagine it is rather simple, but this has me stumped. Any help much appreachiated. Cheers, Chris

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• Programming concepts taken from the arts and humanities

  - by Joey Adams

  After reading Paul Graham's essay Hackers and Painters and Joel Spolsky's Advice for Computer Science College Students, I think I've finally gotten it through my thick skull that I should not be loath to work hard in academic courses that aren't "programming" or "computer science" courses. To quote the former: I've found that the best sources of ideas are not the other fields that have the word "computer" in their names, but the other fields inhabited by makers. Painting has been a much richer source of ideas than the theory of computation. — Paul Graham, "Hackers and Painters" There are certainly other, much stronger reasons to work hard in the "boring" classes. However, it'd also be neat to know that these classes may someday inspire me in programming. My question is: what are some specific examples where ideas from literature, art, humanities, philosophy, and other fields made their way into programming? In particular, ideas that weren't obviously applied the way they were meant to (like most math and domain-specific knowledge), but instead gave utterance or inspiration to a program's design and choice of names. Good examples: The term endian comes from Gulliver's Travels by Tom Swift (see here), where it refers to the trivial matter of which side people crack open their eggs. The terms journal and transaction refer to nearly identical concepts in both filesystem design and double-entry bookkeeping (financial accounting). mkfs.ext2 even says: Writing superblocks and filesystem accounting information: done Off-topic: Learning to write English well is important, as it enables a programmer to document and evangelize his/her software, as well as appear competent to other programmers online. Trigonometry is used in 2D and 3D games to implement rotation and direction aspects. Knowing finance will come in handy if you want to write an accounting package. Knowing XYZ will come in handy if you want to write an XYZ package. Arguably on-topic: The Monad class in Haskell is based on a concept by the same name from category theory. Actually, Monads in Haskell are monads in the category of Haskell types and functions. Whatever that means...

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• What happens when my domain provider cancels order after domain transfer?

  - by Saifur Rahman Mohsin

  I purchased 2 domains say xyz.in and abc.com on october 2012 and I got emails that they will be expiring on oct 2013. I called my local domain provider and told him I'd like to transfer the domain from Webiq to GoDaddy to which he said I cannot unless the domain is active. He asked me to pay for both the domains, renew it and then I could transfer the domain via the domain panel. When I went to the domain panel I noticed that the order was made and so I made a transfer which happened successfully. Just as he mentioned the period of validity (1 year) for each domain got transferred to GoDaddy as well! Additionally, I added 1 year of period to both the domain via GoDaddy so both of them and also GoDaddy provided an extra free year to both these domains as I paid for the transfer on 11/10/2013 at 9:18 PM MST so both of these were stated to be valid till 2016 and that's what it showed when I did a whois lookup as well. But now it suddenly shows me that my domains are getting expired this year (and the whois also shows 2015). This is confusing as I have no idea who to blame for the missing one year. I'm wondering what would have happened say if my old domain provider's client who got my domain registered cancelled the order. Since it was no longer under their control would they still be able to deduce that one year? When I tried submitting a support request to Webiq they replied: Your domain "abc.com" has been transferred away from us on 17-11-2013 and the domain "xyz.in" was transferred away from us on 18-01-2014. There are no order cancellation actions placed. If you have any billing related issues kindly contact your parent reseller. I need some guidance on explaining what issue might have occurred or understanding how this domain control works!

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• Writing the correct value in the depth buffer when using ray-casting

  - by hidayat

  I am doing a ray-casting in a 3d texture until I hit a correct value. I am doing the ray-casting in a cube and the cube corners are already in world coordinates so I don't have to multiply the vertices with the modelviewmatrix to get the correct position. Vertex shader world_coordinate_ = gl_Vertex; Fragment shader vec3 direction = (world_coordinate_.xyz - cameraPosition_); direction = normalize(direction); for (float k = 0.0; k < steps; k += 1.0) { .... pos += direction*delta_step; float thisLum = texture3D(texture3_, pos).r; if(thisLum > surface_) ... } Everything works as expected, what I now want is to sample the correct value to the depth buffer. The value that is now written to the depth buffer is the cube coordinate. But I want the value of pos in the 3d texture to be written. So lets say the cube is placed 10 away from origin in -z and the size is 10*10*10. My solution that does not work correctly is this: pos *= 10; pos.z += 10; pos.z *= -1; vec4 depth_vec = gl_ProjectionMatrix * vec4(pos.xyz, 1.0); float depth = ((depth_vec.z / depth_vec.w) + 1.0) * 0.5; gl_FragDepth = depth;

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• Rotate a particle system

  - by Blueski

  Languages / Libraries in use: C++, OpenGL, GLUT Okay, here's the deal. I've got a particle system which shoots out alpha blended textures to produce a flame. The system only keeps track of very basic things such as, time alive, life, xyz and spread. The direction in which the flames are currently moving in is purely based on other things which are going on in my code ( I assume ). My goal however, is to attach the flame to the camera (DONE) and have the flame pointing in the direction my camera is facing (NOT WORKING). I've tried glRotate for both x,y,z and I can't get it to work properly. I'm currently using gluLookAt to move the camera, and get the flame to follow the XYZ of the camera by calling glTranslatef(camX, camY - offset, camZ); Any suggestions on how I can rotate the direction of the flame with the camera would be greatly appreciated. Heres an image of what I've got: http://i.imgur.com/YhV4w.png Notes: Crosshair depicts where camera is facing if I turn the camera, flame doesn't follow the crosshair Also asked here: http://stackoverflow.com/questions/9560396/rotate-a-particle-system but was referred here

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• Do any CDN services offer multiple urls (or aliases) for your files?

  - by Jakobud

  Lets say a company has multiple commercial web properties that happen to use a lot of the same images on each site. For SEO reasons, the sites must not appear to be related to eachother in any way. This means that the sites can't all link to the same image, even though they all use the same one. Therefore, an image is uploaded to each site and served from each site separately. In order to improve maintainability and latency, lets say the company wanted to use a CDN service. What I'm wondering is, if you upload a file, like an image or something, to a CDN, is there basically one single URL that you access that image at? Or do some (or all) CDN services offer alias URLs so that you can access the same resource from multiple URLs? Example of undesirable situation: Both sites link to the same file URL Site ABC links to <img src="http://123.cdnservice.com/some-path/myimage.jpg"/> Site XYZ links to <img src="http://123.cdnservice.com/some-path/myimage.jpg"/> Example of DESIRABLE situation: Both sites link to the same file via different URLs Site ABC links to <img src="http://123.cdnservice.com/some-path/myimage.jpg"/> Site XYZ links to <img src="http://123.cdnservice.com/some-alias-path/myimage.jpg"/> So in the end, there is only one single file, myimage.jpg on the CDN server, but it is accessible from multiple URLs. Is this possible with CDN services? I know this would make browsers cache the same image twice, but at least it would be better for maintainability. Only one file would ever have to be uploaded.

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• Strange if-else branching behavior in a fragment shader

  - by Winged

  In my fragment shader I have passed an uniform int uLightType variable, which indicates what type of light is in usage right now. The problem is that if-else branching does not work correctly - the fragment shader performs instructions in every if statement block. if (uLightType == 1) { // Spotlight light type vec3 depthTextureCoord = vDepthPosition.xyz / vDepthPosition.w; shadowDepth = unpack(texture2D(uDepthMapSampler, depthTextureCoord.xy)); } else if (uLightType == 2) { // Omni-directional light type shadowDepth = unpack(textureCube(uDepthCubemapSampler, -lightVec)); } In the case when uLightType equals 1, unless I comment out the content of the second if block, it assigns an another value to shadowDepth. Also while uLightType equals 1, when I remove the second 'if' block and change == to != like in the sample code below, nothing happens (which means that uLightType really equals 1). if (uLightType != 1) { // Spotlight light type vec3 depthTextureCoord = vDepthPosition.xyz / vDepthPosition.w; shadowDepth = unpack(texture2D(uDepthMapSampler, depthTextureCoord.xy)); } Also, when I manually create an int variable (which is not an uniform) like this: var lightType = 1; and replace uLightType with it in the if-else branch, everything works fine, so I guess it have something to do with the fact that uLightType is the uniform.

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• Flickering when accessing texture by offset

  - by TravisG

  I have this simple compute shader that basically just takes the input from one image and writes it to another. Both images are 128/128/128 in size and glDispatchCompute is called with (128/8,128/8,128/8). The source images are cleared to 0 before this compute shader is executed, so no undefined values should be floating around in there. (I have the appropriate memory barrier on the C++ side set before the 3D texture is accessed). This version works fine: #version 430 layout (location = 0, rgba16f) uniform image3D ping; layout (location = 1, rgba16f) uniform image3D pong; layout (local_size_x = 8, local_size_y = 8, local_size_z = 8) in; void main() { ivec3 sampleCoord = gl_GlobalInvocationID.xyz; imageStore(pong, imageLoad(ping,sampleCoord)); } Reading values from pong shows that it's just a copy, as intended. However, when I load data from ping with an offset: #version 430 layout (location = 0, rgba16f) uniform image3D ping; layout (location = 1, rgba16f) uniform image3D pong; layout (local_size_x = 8, local_size_y = 8, local_size_z = 8) in; void main() { ivec3 sampleCoord = gl_GlobalInvocationID.xyz; imageStore(pong, imageLoad(ping,sampleCoord+ivec3(1,0,0))); } The data that is written to pong seems to depend on the order of execution of the threads within the work groups, which makes no sense to me. When reading from the pong texture, visible flickering occurs in some spots on the texture. What am I doing wrong here?

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• problems texture mapping in modern OpenGL 3.3 using GLSL #version 150

  - by RubyKing

  Hi all I'm trying to do texture mapping using Modern OpenGL and GLSL 150. The problem is the texture shows but has this weird flicker I can show a video here http://www.youtube.com/watch?v=xbzw_LMxlHw and I have everything setup best I can have my texcords in my vertex array sent up to opengl I have my fragment color set to the texture values and texel values I have my vertex sending the textures cords to texture cordinates to be used in the fragment shader I have my ins and outs setup and I still don't know what I'm missing that could be causing that flicker. here is my code FRAGMENT SHADER #version 150 uniform sampler2D texture; in vec2 texture_coord; varying vec3 texture_coordinate; void main(void){ gl_FragColor = texture(texture, texture_coord); } VERTEX SHADER #version 150 in vec4 position; out vec2 texture_coordinate; out vec2 texture_coord; uniform vec3 translations; void main() { texture_coord = (texture_coordinate); gl_Position = vec4(position.xyz + translations.xyz, 1.0); } Last bit here is my vertex array with texture cordinates GLfloat vVerts[] = { 0.5f, 0.5f, 0.0f, 0.0f, 1.0f , 0.0f, 0.5f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.5f, 0.0f, 0.0f, 1.0f, 0.0f}; //tex x and y HERE IS THE ACTUAL FULL SOURCE CODE if you need to see all the code in its fullest glory here is a link to every file http://ideone.com/7kQN3 thank you for your help

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• implementing dynamic query handler on historical data

  - by user2390183

  EDIT : Refined question to focus on the core issue Context: I have historical data about property (house) sales collected from various sources in a centralized/cloud data source (assume info collection is handled by a third party) Planning to develop an application to query and retrieve data from this centralized data source Example Queries: Simple : for given XYZ post code, what is average house price for 3 bed room house? Complex: What is estimated price for an house at "DD,Some Street,XYZ Post Code" (worked out from average values of historic data filtered by various characteristics of the house: house post code, no of bed rooms, total area, and other deeper insights like house building type, year of built, features)? In addition to average price, the application should support other property info ** maximum, or minimum price..etc and trend (graph) on a selected property attribute over a period of time**. Hence, the queries should not enforce the search based on a primary key or few fixed fields In other words, queries can be What is the change in 3 Bed Room house price (irrespective of location) over last 30 days? What kind of properties we can get for X price (irrespective of location or house type) The challenge I have is identifying the domain (BI/ Data Analytical or DB Design or DB Query Interface or DW related or something else) this problem (dynamic query on historic data) belong to, so that I can do further exploration My findings so far I could be wrong on the following, so please correct me if you think so I briefly read about BI/Data Analytics - I think it is heavy weight solution for my problem and has scalability issues. DB Design - As I understand RDBMS works well if you know Data model at design time. I am expecting attributes about property or other entity (user) that am going to bring in, would evolve quickly. hence maintenance would be an issue. As I am going to have multiple users executing query at same time, performance would be a bottleneck Other options like Graph DB (http://www.tinkerpop.com/) seems to be bit complex (they are good. but using those tools meant for generic purpose, make me think like assembly programming to solve my problem ) BigData related solution are to analyse data from multiple unrelated domains So, Any suggestion on the space this problem fit in ? (Especially if you have design/implementation experience of back-end for property listing or similar portals)

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• Location-Based redirection and duplication in sub-directories affecting SEO

  - by Joshua

  I currently own the website www.xyz.com. The website has a sub-directory for each of the 3 target countries: .../en-US/ (United States), .../es-MX/ (Mexico), and .../es-DO/ (Dominican Republic). I have two main questions about this setup: Currently, the main domain/root (xyz.com) contains a blank index.php file, but I would like for a user to be redirected to one of the sub-directories based on their regional location. What is the best way to accomplish this? I have looked at using browser language-based redirection, but how would I know whether to direct a user to the MX or DO site if the browser language is set to spanish? Is there a way to detect a user's geographic location? Also, the 3 websites are practically identical except they all have 3 unique color schemes and the US site is in english while the MX and DO sites are in spanish. My problem is that I believe GoogleBot is penalizing/banning my site because the spanish text on the MX and DO pages are nearly identical and are thus marked as duplicates/spam. Is there a way to avoid this?

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• Proper way to do texture mapping in modern OpenGL?

  - by RubyKing

  I'm trying to do texture mapping using OpenGL 3.3 and GLSL 150. The problem is the texture shows but has this weird flicker I can show a video here. My texcords are in a vertex array. I have my fragment color set to the texture values and texel values. I have my vertex shader sending the texture cords to texture cordinates to be used in the fragment shader. I have my ins and outs setup and I still don't know what I'm missing that could be causing that flicker. Here is my code: Fragment shader #version 150 uniform sampler2D texture; in vec2 texture_coord; varying vec3 texture_coordinate; void main(void) { gl_FragColor = texture(texture, texture_coord); } Vertex shader #version 150 in vec4 position; out vec2 texture_coordinate; out vec2 texture_coord; uniform vec3 translations; void main() { texture_coord = (texture_coordinate); gl_Position = vec4(position.xyz + translations.xyz, 1.0); } Last bit Here is my vertex array with texture coordinates: GLfloat vVerts[] = { 0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 0.5f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.5f, 0.0f, 0.0f, 1.0f, 0.0f}; //tex x and y If you need to see all the code, here is a link to every file. Thank you for your help.

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• AWS: setting up auto-scale for EC2 instances

  - by Elton Stoneman

  Originally posted on: http://geekswithblogs.net/EltonStoneman/archive/2013/10/16/aws-setting-up-auto-scale-for-ec2-instances.aspxWith Amazon Web Services, there’s no direct equivalent to Azure Worker Roles – no Elastic Beanstalk-style application for .NET background workers. But you can get the auto-scale part by configuring an auto-scaling group for your EC2 instance. This is a step-by-step guide, that shows you how to create the auto-scaling configuration, which for EC2 you need to do with the command line, and then link your scaling policies to CloudWatch alarms in the Web console. I’m using queue size as my metric for CloudWatch,  which is a good fit if your background workers are pulling messages from a queue and processing them.  If the queue is getting too big, the “high” alarm will fire and spin up a new instance to share the workload. If the queue is draining down, the “low” alarm will fire and shut down one of the instances. To start with, you need to manually set up your app in an EC2 VM, for a background worker that would mean hosting your code in a Windows Service (I always use Topshelf). If you’re dual-running Azure and AWS, then you can isolate your logic in one library, with a generic entry point that has Start() and Stop()  functions, so your Worker Role and Windows Service are essentially using the same code. When you have your instance set up with the Windows Service running automatically, and you’ve tested it starts up and works properly from a reboot, shut the machine down and take an image of the VM, using Create Image (EBS AMI) from the Web Console: When that completes, you’ll have your own AMI which you can use to spin up new instances, and you’re ready to create your auto-scaling group. You need to dip into the command-line tools for this, so follow this guide to set up the AWS autoscale command line tool. Now we’re ready to go. 1. Create a launch configuration This launch configuration tells AWS what to do when a new instance needs to be spun up. You create it with the as-create-launch-config command, which looks like this: as-create-launch-config sc-xyz-launcher # name of the launch config --image-id ami-7b9e9f12 # id of the AMI you extracted from your VM --region eu-west-1 # which region the new instance gets created in --instance-type t1.micro # size of the instance to create --group quicklaunch-1 #security group for the new instance 2. Create an auto-scaling group The auto-scaling group links to the launch config, and defines the overall configuration of the collection of instances: as-create-auto-scaling-group sc-xyz-asg # auto-scaling group name --region eu-west-1 # region to create in --launch-configuration sc-xyz-launcher # name of the launch config to invoke for new instances --min-size 1 # minimum number of nodes in the group --max-size 5 # maximum number of nodes in the group --default-cooldown 300 # period to wait (in seconds) after each scaling event, before checking if another scaling event is required --availability-zones eu-west-1a eu-west-1b eu-west-1c # which availability zones you want your instances to be allocated in – multiple entries means EC@ will use any of them 3. Create a scale-up policy The policy dictates what will happen in response to a scaling event being triggered from a “high” alarm being breached. It links to the auto-scaling group; this sample results in one additional node being spun up: as-put-scaling-policy scale-up-policy # policy name -g sc-psod-woker-asg # auto-scaling group the policy works with --adjustment 1 # size of the adjustment --region eu-west-1 # region --type ChangeInCapacity # type of adjustment, this specifies a fixed number of nodes, but you can use PercentChangeInCapacity to make an adjustment relative to the current number of nodes, e.g. increasing by 50% 4. Create a scale-down policy The policy dictates what will happen in response to a scaling event being triggered from a “low” alarm being breached. It links to the auto-scaling group; this sample results in one node from the group being taken offline: as-put-scaling-policy scale-down-policy -g sc-psod-woker-asg "--adjustment=-1" # in Windows, use double-quotes to surround a negative adjustment value –-type ChangeInCapacity --region eu-west-1 5. Create a “high” CloudWatch alarm We’re done with the command line now. In the Web Console, open up the CloudWatch view and create a new alarm. This alarm will monitor your metrics and invoke the scale-up policy from your auto-scaling group, when the group is working too hard. Configure your metric – this example will fire the alarm if there are more than 10 messages in my queue for over a minute: Then link the alarm to the scale-up policy in your group: 6. Create a “low” CloudWatch alarm The opposite of step 4, this alarm will trigger when the instances in your group don’t have enough work to do (e.g fewer than 2 messages in the queue for 1 minute), and will invoke the scale-down policy. And that’s it. You don’t need your original VM as the auto-scale group has a minimum number of nodes connected. You can test out the scaling by flexing your CloudWatch metric – in this example, filling up a queue from a  stub publisher – and watching AWS create new nodes as required, then stopping the publisher and watch AWS kill off the spare nodes.

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