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  • DallasXAML.com – A New User Group for Silverlight, WPF, XBAP, etc.

    - by vblasberg
                                     http://DallasXAML.com   I’ve devoted much of last month to starting the DallasXAML User Group.  I finally got back into user group management after 2 years away from leading the Dallas C# SIG.  Now I’m having fun getting a Silverlight/WPF user group going strong for the Dallas / Ft. Worth community.  Our first meeting was March 3rd at the Improving Enterprises offices in North Dallas.  We had about 25 to 35 attendees in the first meeting and it went well.  We covered the most important topic that everyone should understand well – data binding.   So I chose the XAML user group so we can get together for a common group improvement in the Dallas / Ft. Worth area and learn cross-technology information that we can use now.  It is not a lecture hall.  The great thing is that we’ll provide hands-on experience with most every meeting.  The goal is to get the experience that we can use the next work day.  I unfortunately broke that rule by speaking all through the first meeting, but next month is part two with more hands-on data binding.   The differentiation is this group concentrates on XAML, not Silverlight or Windows Client alone.  What we learn in one area, we gain for all areas.  That includes the Silverlight for Windows Phone 7 coming later this year.  Next year it may be Windows Phone 8, 9, or whatever.    I started developing WPF seriously almost a year ago.  I experienced the painful learning curve.  Anyone who reports that there isn’t a big learning curve either thinks in XAML before it was developed, is on the Silverlight or WPF development team, or has already conquered the learning and forgot the pain.  So I wanted to share the pain or make it easier for others – same thing.  I have found that the more I learn and use good disciplined techniques, the more interesting and rewarding development is again.   A few months ago, I was sitting in the iPhone development session at the Dallas C# SIG.  After the meeting, the audience was polled for future topics.  After a few suggestions, Silverlight got the big hands up.  That makes sense because it’s still the hot topic for many Microsoft developers.  So I surfed around and found that there aren’t enough user groups to help in this area.  I polled a few local group leaders and did the work to start the group.  This week I got a telerik controls licence and improved the site with some great controls, namely the RadHtmlPlaceholder control.  It provides a Silverlight control to show HTML in an IFrame-like area.  On DallasXAML.com, the newsletters and resource pages display in HTML because Silverlight just isn’t there yet.  I’m looking forward to a Silverlight XPS viewer with flow documents.  There are some good commercial version available, but this is a non-profit group.    The DallasXAML.com site points to many other resources such as podcasts and webcasts.  I would rather give them the credit than try to out-do them.  So check out the DallasXAML user group site and attend our meetings if you can.  We meet the first Tuesday of the month.   -Vince DallasXAML User Group Leader  

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  • CSM shadow errors when models are split

    - by KaiserJohaan
    I'm getting closer to fixing CSM, but there seems to be one more issue at hand. At certain angles, the models will be caught/split between two shadow map cascades, like below. first depth split second depth split - here you can see the model is caught between the splits How does one fix this? Increase the overlapping boundaries between the splits? Or is the frustrum erronous? CameraFrustrum CalculateCameraFrustrum(const float fovDegrees, const float aspectRatio, const float minDist, const float maxDist, const Mat4& cameraViewMatrix, Mat4& outFrustrumMat) { CameraFrustrum ret = { Vec4(1.0f, -1.0f, 0.0f, 1.0f), Vec4(1.0f, 1.0f, 0.0f, 1.0f), Vec4(-1.0f, 1.0f, 0.0f, 1.0f), Vec4(-1.0f, -1.0f, 0.0f, 1.0f), Vec4(1.0f, -1.0f, 1.0f, 1.0f), Vec4(1.0f, 1.0f, 1.0f, 1.0f), Vec4(-1.0f, 1.0f, 1.0f, 1.0f), Vec4(-1.0f, -1.0f, 1.0f, 1.0f), }; const Mat4 perspectiveMatrix = PerspectiveMatrixFov(fovDegrees, aspectRatio, minDist, maxDist); const Mat4 invMVP = glm::inverse(perspectiveMatrix * cameraViewMatrix); outFrustrumMat = invMVP; for (Vec4& corner : ret) { corner = invMVP * corner; corner /= corner.w; } return ret; } Mat4 CreateDirLightVPMatrix(const CameraFrustrum& cameraFrustrum, const Vec3& lightDir) { Mat4 lightViewMatrix = glm::lookAt(Vec3(0.0f), -glm::normalize(lightDir), Vec3(0.0f, -1.0f, 0.0f)); Vec4 transf = lightViewMatrix * cameraFrustrum[0]; float maxZ = transf.z, minZ = transf.z; float maxX = transf.x, minX = transf.x; float maxY = transf.y, minY = transf.y; for (uint32_t i = 1; i < 8; i++) { transf = lightViewMatrix * cameraFrustrum[i]; if (transf.z > maxZ) maxZ = transf.z; if (transf.z < minZ) minZ = transf.z; if (transf.x > maxX) maxX = transf.x; if (transf.x < minX) minX = transf.x; if (transf.y > maxY) maxY = transf.y; if (transf.y < minY) minY = transf.y; } Mat4 viewMatrix(lightViewMatrix); viewMatrix[3][0] = -(minX + maxX) * 0.5f; viewMatrix[3][1] = -(minY + maxY) * 0.5f; viewMatrix[3][2] = -(minZ + maxZ) * 0.5f; viewMatrix[0][3] = 0.0f; viewMatrix[1][3] = 0.0f; viewMatrix[2][3] = 0.0f; viewMatrix[3][3] = 1.0f; Vec3 halfExtents((maxX - minX) * 0.5, (maxY - minY) * 0.5, (maxZ - minZ) * 0.5); return OrthographicMatrix(-halfExtents.x, halfExtents.x, halfExtents.y, -halfExtents.y, halfExtents.z, -halfExtents.z) * viewMatrix; }

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  • A story of Murphy&ndash;my technical issues at TechDays Switzerland #chtd

    - by Laurent Bugnion
    I had two sessions at the recent Swiss TechDays. While the first one (Advanced Development for Windows Phone 8) went extremely well (I think), I had a very annoying technical issue in the beginning of my second session. First let me add that I talked to Microsoft about that and I hope they will change a few things in the room assignment for next year. My two sessions were one right after the other, with only 15 minutes break to change room. I don’t mind having two sessions so close from each other, but I would really like them to be in the same room in order to avoid having to move my laptops (plural, that will become important later) and redoing the tech check. That being said, I am guilty of not checking where my talks would be before the day before the conference, and when I did notice, it was too late to change it. After my first session, I quickly moved to the other room and setup my main laptop, a Dell Precision. We tested the video output (VGA) and didn’t notice anything special. The projectors are using a fairly high resolution (kudos to the Basel conference center for not having old school 1024x768 projectors anymore, that makes Blend really hard to demo ;) but since everything went great during the first talk, I was not worried. In fact I even had some time to chat with some early attendees about my Microsoft Surface and the Samsung Slate 7, which I had carried with me in addition to the Precision. I just thought it would be nice to show the hardware that Windows 8 can run on, without thinking any further. When the session started, I immediately noticed that the main screen was not showing anything. I thought I had just forgotten to switch to “duplicate” for the video output, and did that with a quick Win-P. However it didn’t “hold”. After 2 seconds, it reverted back to a black display for my attendees. Then I started to really worry. We tried everything, switching from VGA to HDMI, changing the resolution, setting the projector as primary display, but nothing did the trick. The projector was just refusing to show my screen. Now, to show you how despaired I started to be, I even considered using the “extend” setting (which worked just fine), and to use one of the feedback monitors on the floor but really it was super cumbersome. Eventually, my last resort arrived: I started my Samsung Slate 7, which by chance has Visual Studio 12 and Blend 5 installed, plugged the HDMI projector in the dock (yes, I had the dock with me, which I usually don’t!), connected it to internet (had to enter a long password for that), loaded the source code from my main machine using a USB stick and…. finally started to give my presentation. All in all I think we lost about 10 minutes. Amongst the most horrible minutes of my whole life, truly (yes I am blessed, I didn’t have that many horrible minutes in my life ;) I really want to apologize to my attendees. We joked a bit during the attempts to resolve the issue, the reactions I had after the session were all very nice and sympathetic. Only a handful of people left my session while I was having the issues, and I really don’t blame them (who knew how long the problem would last!!). But still, I probably talked at more than 60 sessions over the years, and this was by far my most painful moment. What did I learn? So what did I learn from this? Well from now on I will always have my slate ready with the latest source code, internet connection and every tool I might need during the presentation. This way, if I detect even a hint that the Precision might not work, I will just switch to the Slate. The experience of presenting on the slate is actually not bad at all, it is just a bit slow for my taste, but it does work. By the way, I will be posting the code and slides for my sessions very soon, I just need to “clean it and zip it”. Stay tuned, and thanks again for your patience in that horrible circumstance. Cheers Laurent   Laurent Bugnion (GalaSoft) Subscribe | Twitter | Facebook | Flickr | LinkedIn

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  • The inevitable Hello World post!

    - by brendonpage
    Greetings to anyone reading this! This is my first of hopefully many posts. I would like to use this post to introduce myself and to let you know what to expect from this blog in future. Okay so a bit about myself. In case you missed the name of this blog, my name is Brendon Page! I am a Software Developer from South Africa and work for a small company who’s main focus is producing software for the kitchen cupboard industry, although from time to time we do produce custom solutions for other industries. I work in a small team of 3, including myself, and am fortunate enough to work from home! I have been involved in IT since 1996, which is when I got my first PC, and started working as a junior programmer in 2003. Outside of work I enjoy playing squash, PC Games and of course LANing with my friends. If I get any free time between all of that I will usually dedicate some of it to a personal project, these are mainly prototypes for an idea I have had or for something that could be useful at work. I was in 2 minds on whether to include a photo of myself. The reason for this was because while I was looking for a suitable photo to use, it dawned on me how much time I dedicate to pulling funny faces in photos! I also realized how little I shave, which I blame completely on working form home. So after much debate here I am, funny face, beard and all!   Now that you know a bit about me lets move onto what expect from this blog. I work predominantly with Microsoft technologies so most if not all of my posts will be related to something Microsoft. Since most of my job entails Software Development you can expect a lot of posts which will deal with the .NET Framework. I am currently working on a large Silverlight project, so my first few posts will be targeted at in that direction. I will be striving to make the content of my posts as useful as possible from both an explanation and code perspective, I aim to include a working solution for every post, which I will put up on my skydrive for download. Here is what I have planned for my next few posts: Where did my session variables go?  Here I will take you through the lessons I learnt the hard way about the ASP.NET session. I am not going to go into to much depth in this post, as there is already a lot of information available on it. I mainly want to cover it in an effort to keep the scope creep of my posts to a minimum, some the solutions I upload will use it and I would like to have a post that I can reference to explain why I am doing something a certain way. Uploading files through SIlverlight Again there is a lot of existing information on this topic, so I wont be going into to much depth, but I will be using the solution from this as a base for my next post. Generating and Displaying DeepZoom images dynamically in Silverlight Well the title pretty much speaks for it’s self on this one. As I mentioned I will be building off the solution that I create in my ‘Uploading files through Silverlight’ post. Securing DeepZoom images using a custom implementation of the MultiScaleTileSource In this post I will look at the privacy issue surrounding the default usage of DeepZoom images in Silverlight and how to overcome it. This makes the use of DeepZoom in privacy conscious applications more viable. Thanks to anyone who actually read this post! I look forward to producing more which will hopefully be helpful to you.

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  • Attending a Career Fair: &ldquo;Don&rsquo;t be shy &ndash; Be prepared&rdquo;

    - by jessica.ebbelaar
    There are a large number of ways to interact with companies nowadays. The career fair is a very effective and personal way to interact with a number of different companies in a very short period of time. Here are some simple tips to help you perform during a career fair. Do research The key to being successful at a career fair is to do research before you go. Make a first selection of the companies you feel could be interesting for you. Include many types of employers. Once you have decided on the list of companies you want to visit, go to their career portal. Inform yourself about what the company does, i.e what roles there are available, how the company culture is described, what impression the testimonials give you. The question that you still have after reviewing this information, are the ones you can discuss with the company on the fair. Sell yourself Visit the companies you have on your top 5 list first, so you will be at your highest energy level to make that first impression. Think in advance about what you are going to tell the recruiter. Prepare a 30-second introduction (including degree, strengths, skills & experience) Be confident when you talk about your experience. Remember to start the conversation with a smile, make good eye contact and give a firm handshake. You could be speaking to your next manager, so be professional! If you already know what jobs you are interested in, relate your skills and experience to the roles that the company has available. If you are not yet sure gather as much information as you can about employment and/or hiring procedures, specific skills necessary for different jobs, training and career paths. Stand out As career fairs are very crowded and the attending companies meet with a lot of potential candidates on one day, you have to make sure you are noticed in a positive way. A good preparation and asking questions that show you have a good understanding of the industry, organization and roles will help you. Be aware of time demands on employers. Do not monopolize an employer's time. Dress appropriately to make a good first impression. Bring your resume Do not forget to bring your resume in print or on a USB-stick to the fair. If you are searching for different types of jobs, bring different versions of your resume. Your resume should be short and professional on white paper that is free of graphics or fancy print styles and containing larger margins for interviewer notes. Follow up After each conversation ask who you can contact for follow-up discussions about the specific roles. Use the back of a business card to record notes that help you remember important details and follow-up instructions. If no card is available, record the contact information and your comments in your notepad or phone. Last but not least, thank everyone you talk to for their time. Follow up as soon as possible with thank you notes that address the companies’ hiring needs, your qualifications, and express your desire for a second interview. What not to do… Do not visit a company with a group of friends. Interact with the companies on your own, to make your own positive impression. Do not walk up to a recruiter and interrupt a current conversation; wait your turn and be polite. What you should absolutely avoid is a grab and run on freebies! Take the time to speak to the company and ask for a freebie at the end of the conversation in case they are not offered to you. Good luck with the preparations for the career fair you will attend. Oracle recruiters look forward to meet you! They will be present on a large number of fairs in the region. For an overview of the fairs go to the Events & Calendar page on http://campus.oracle.com If you have any questions related to this article feel free to contact [email protected].

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  • Ubuntu keyboard shortcuts - two-part question

    - by Don
    Background: I come from a Windows background and just started dual-booting Ubuntu (my first Linux experience) about 4 days ago. So my systems are Windows 7/Ubuntu 12.04, and so far I'm loving Ubuntu. I am a dedicated mouse-abolitionist (trackpads are hell) and do most of my browsing and navigation with keyboard shortcuts. However, on switching to Ubuntu, a lot of my keyboard shortcuts are gone, and my productivity has resultantly taken a huge hit anytime I am using Ubuntu. Problem 1: My computer was designed to display on-screen notifications for a second when I hit caps-lock or num-lock, and there are no constant indicators of the lock status (LEDs, etc). In Ubuntu, the keys still worked, but the notifications were gone. Googling got me a tutorial on key-binding(Compiz) and scripts, so now I have capslock and numlock running this script: #!/bin/bash icon="/usr/share/icons/gnome/scalable/devices/keyboard.svg" case $1 in 'scrl') mask=3 key="Scroll" ;; 'num') mask=2 key="Num" ;; 'caps') mask=1 key="Caps" ;; esac value=$(xset q | grep "LED mask" | sed -r "s/.*LED mask:\s+[0-9a-fA-F]+([0-9a-fA-F]).*/\1/") if [ $(( 0x$value & 0x$mask )) == $mask ] then output="$key Lock" output2="On" else output="$key Lock" output2="Off" fi notify-send -i $icon "$output" "$output2" -t 1000 But, whether turning it off or on, the notifications always say that I have turned it on. Is there an easy fix for this, or an easier way to work it to get it do display the CORRECT notifications? Problem 2: I'm not sure if this is because of my keyboard or Ubuntu. In Windows, I use Chrome and use the ctrl+pgUp/pgDwn shortcuts quite a bit to switch between tabs. On my keyboard, I can enter pgUp and pgDwn by either disabling NumLock and hitting 9 or 3 respectively on the 10key. Alternately I can hold the fn key and hit up or down arrow. The first method is the one I very heavily relied upon, and it works in Firefox for Ubuntu, but not in Chrome nor in Chromium. The second method (ctrl + fn + up/down) works fine in Chrome. However, I'd dearly like to find a method to make the first method work. Any suggestions? Thanks in advance for your help. Update: @julien: I've checked the keyboard layout options - I didn't find anything that seemed useful for this goal. @Marty: The script runs once when the button is pressed. In Compiz, I've tied those two keys to the script, so when I press the button, it runs the script with the button pressed as a parameter. Update: @elmicha: Thanks. That one works a lot better, and it even pops an icon into the status bar when caps lock is on. There's still a very slight problem in that if I quickly tap the key twice, the image will show that it has been turned on and then turned off, and the notifaction will come and go from my status area, but the text of both notifications will be "Caps Lock on". Same with Num Lock. However, if the time between presses is long enough for the first notification to disappear, everything displays correctly. Given how quickly the notifications disappear, I don't expect this will pose too much of a problem for me.

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  • Incorrect lighting results with deferred rendering

    - by Lasse
    I am trying to render a light-pass to a texture which I will later apply on the scene. But I seem to calculate the light position wrong. I am working on view-space. In the image above, I am outputting the attenuation of a point light which is currently covering the whole screen. The light is at 0,10,0 position, and I transform it to view-space first: Vector4 pos; Vector4 tmp = new Vector4 (light.Position, 1); // Transform light position for shader Vector4.Transform (ref tmp, ref Camera.ViewMatrix, out pos); shader.SendUniform ("LightViewPosition", ref pos); Now to me that does not look as it should. What I think it should look like is that the white area should be on the center of the scene. The camera is at the corner of the scene, and it seems as if the light would move along with the camera. Here's the fragment shader code: void main(){ // default black color vec3 color = vec3(0); // Pixel coordinates on screen without depth vec2 PixelCoordinates = gl_FragCoord.xy / ScreenSize; // Get pixel position using depth from texture vec4 depthtexel = texture( DepthTexture, PixelCoordinates ); float depthSample = unpack_depth(depthtexel); // Get pixel coordinates on camera-space by multiplying the // coordinate on screen-space by inverse projection matrix vec4 world = (ImP * RemapMatrix * vec4(PixelCoordinates, depthSample, 1.0)); // Undo the perspective calculations vec3 pixelPosition = (world.xyz / world.w) * 3; // How far the light should reach from it's point of origin float lightReach = LightColor.a / 2; // Vector in between light and pixel vec3 lightDir = (LightViewPosition.xyz - pixelPosition); float lightDistance = length(lightDir); vec3 lightDirN = normalize(lightDir); // Discard pixels too far from light source //if(lightReach < lightDistance) discard; // Get normal from texture vec3 normal = normalize((texture( NormalTexture, PixelCoordinates ).xyz * 2) - 1); // Half vector between the light direction and eye, used for specular component vec3 halfVector = normalize(lightDirN + normalize(-pixelPosition)); // Dot product of normal and light direction float NdotL = dot(normal, lightDirN); float attenuation = pow(lightReach / lightDistance, LightFalloff); // If pixel is lit by the light if(NdotL > 0) { // I have moved stuff from here to above so I can debug them. // Diffuse light color color += LightColor.rgb * NdotL * attenuation; // Specular light color color += LightColor.xyz * pow(max(dot(halfVector, normal), 0.0), 4.0) * attenuation; } RT0 = vec4(color, 1); //RT0 = vec4(pixelPosition, 1); //RT0 = vec4(depthSample, depthSample, depthSample, 1); //RT0 = vec4(NdotL, NdotL, NdotL, 1); RT0 = vec4(attenuation, attenuation, attenuation, 1); //RT0 = vec4(lightReach, lightReach, lightReach, 1); //RT0 = depthtexel; //RT0 = 100 / vec4(lightDistance, lightDistance, lightDistance, 1); //RT0 = vec4(lightDirN, 1); //RT0 = vec4(halfVector, 1); //RT0 = vec4(LightColor.xyz,1); //RT0 = vec4(LightViewPosition.xyz/100, 1); //RT0 = vec4(LightPosition.xyz, 1); //RT0 = vec4(normal,1); } What am I doing wrong here?

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  • X server with nvidia driver crashing: 12.04

    - by Raster
    My X server consistently crashes. It seems like this is happening when the X server is idle. This behaviour is new with 12.04. This is only happening on the second display of a multiseat system. Is there a configuration change I can make to stop this? X.Org X Server 1.11.3 Release Date: 2011-12-16 X Protocol Version 11, Revision 0 Build Operating System: Linux 2.6.42-26-generic x86_64 Ubuntu Current Operating System: Linux Desktop 3.2.0-29-generic #46-Ubuntu SMP Fri Jul 27 17:03:23 UTC 2012 x86_64 Kernel command line: BOOT_IMAGE=/vmlinuz-3.2.0-29-generic root=/dev/mapper/Group1-Root ro ramdisk_size=512000 quiet splash vt.handoff=7 Build Date: 04 August 2012 01:51:23AM xorg-server 2:1.11.4-0ubuntu10.7 (For technical support please see http://www.ubuntu.com/support) Current version of pixman: 0.24.4 Before reporting problems, check http://wiki.x.org to make sure that you have the latest version. Markers: (--) probed, (**) from config file, (==) default setting, (++) from command line, (!!) notice, (II) informational, (WW) warning, (EE) error, (NI) not implemented, (??) unknown. (==) Log file: "/var/log/Xorg.1.log", Time: Sun Sep 2 22:37:06 2012 (==) Using config file: "/etc/X11/xorg.conf" (==) Using system config directory "/usr/share/X11/xorg.conf.d" Backtrace: 0: /usr/bin/X (xorg_backtrace+0x26) [0x7fcee86be846] 1: /usr/bin/X (0x7fcee8536000+0x18c6ea) [0x7fcee86c26ea] 2: /lib/x86_64-linux-gnu/libpthread.so.0 (0x7fcee785c000+0xfcb0) [0x7fcee786bcb0] 3: /usr/lib/x86_64-linux-gnu/xorg/extra-modules/nvidia_drv.so (0x7fcee14ba000+0x902a9) [0x7fcee154a2a9] 4: /usr/lib/x86_64-linux-gnu/xorg/extra-modules/nvidia_drv.so (0x7fcee14ba000+0xfd5e7) [0x7fcee15b75e7] 5: /usr/lib/x86_64-linux-gnu/xorg/extra-modules/nvidia_drv.so (0x7fcee14ba000+0x4d6b92) [0x7fcee1990b92] 6: /usr/lib/x86_64-linux-gnu/xorg/extra-modules/nvidia_drv.so (0x7fcee14ba000+0x4d74d5) [0x7fcee19914d5] 7: /usr/lib/x86_64-linux-gnu/xorg/extra-modules/nvidia_drv.so (0x7fcee14ba000+0x4d767d) [0x7fcee199167d] 8: /usr/bin/X (0x7fcee8536000+0x1196ec) [0x7fcee864f6ec] 9: /usr/bin/X (0x7fcee8536000+0xe8ad5) [0x7fcee861ead5] 10: /usr/bin/X (0x7fcee8536000+0xe9d45) [0x7fcee861fd45] /etc/X11/xorg.conf Section "ServerLayout" Identifier "Desktop" Screen 0 "DesktopScreen" 0 0 InputDevice "DesktopMouse" "CorePointer" InputDevice "DesktopKeyboard" "CoreKeyboard" Option "AutoAddDevices" "false" Option "AllowEmptyInput" "true" Option "AutoEnableDevices" "false" EndSection Section "ServerLayout" Identifier "Desktop2" Screen 1 "Desktop2Screen" 0 0 InputDevice "Desktop2Mouse" "CorePointer" InputDevice "Desktop2Keyboard" "CoreKeyboard" Option "AutoAddDevices" "false" Option "AllowEmptyInput" "true" Option "AutoEnableDevices" "false" EndSection Section "Module" Load "dbe" Load "extmod" Load "type1" Load "freetype" Load "glx" EndSection Section "Files" EndSection Section "ServerFlags" Option "AutoAddDevices" "false" Option "AutoEnableDevices" "false" Option "AllowMouseOpenFail" "on" Option "AllowEmptyInput" "on" Option "ZapWarning" "on" Option "HandleSepcialKeys" "off" # Zapping on Option "DRI2" "on" Option "Xinerama" "0" EndSection # Desktop Mouse Section "InputDevice" Identifier "DesktopMouse" Driver "evdev" Option "Device" "/dev/input/event3" Option "Protocol" "auto" Option "GrabDevice" "on" Option "Emulate3Buttons" "no" Option "Buttons" "5" Option "ZAxisMapping" "4 5" Option "SendCoreEvents" "true" EndSection # Desktop2 Mouse Section "InputDevice" Identifier "Desktop2Mouse" Driver "evdev" Option "Device" "/dev/input/event5" Option "Protocol" "auto" Option "GrabDevice" "on" Option "Emulate3Buttons" "no" Option "Buttons" "5" Option "ZAxisMapping" "4 5" Option "SendCoreEvents" "true" EndSection Section "InputDevice" Identifier "DesktopKeyboard" Driver "evdev" Option "Device" "/dev/input/event4" Option "XkbRules" "xorg" Option "XkbModel" "105" Option "XkbLayout" "us" Option "Protocol" "Standard" Option "GrabDevice" "on" EndSection Section "InputDevice" Identifier "Desktop2Keyboard" Driver "evdev" Option "Device" "/dev/input/event6" Option "XkbRules" "xorg" Option "XkbModel" "105" Option "XkbLayout" "us" Option "Protocol" "Standard" Option "GrabDevice" "on" EndSection Section "Monitor" Identifier "Desktop2Monitor" VendorName "Acer" ModelName "Acer G235H" HorizSync 30.0 - 83.0 VertRefresh 56.0 - 75.0 Option "DPMS" EndSection Section "Monitor" Identifier "DesktopMonitor" VendorName "Acer" ModelName "Acer H213H" HorizSync 30.0 - 83.0 VertRefresh 56.0 - 75.0 Option "DPMS" EndSection Section "Device" Identifier "EVGACard" Driver "nvidia" VendorName "NVIDIA Corporation" BoardName "GeForce GTX 560 Ti" Option "Coolbits" "1" BusID "PCI:2:0:0" Screen 0 EndSection Section "Device" Identifier "XFXCard" Driver "nvidia" VendorName "NVIDIA Corporation" BoardName "GeForce GTX 9800" Option "Coolbits" "1" BusID "PCI:5:0:0" Screen 0 EndSection Section "Screen" Identifier "DesktopScreen" Device "EVGACard" Monitor "DesktopMonitor" DefaultDepth 24 SubSection "Display" Depth 24 EndSubSection EndSection Section "Screen" Identifier "Desktop2Screen" Device "XFXCard" Monitor "Desktop2Monitor" DefaultDepth 24 SubSection "Display" Depth 24 EndSubSection EndSection

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  • HLSL 5 interpolation issues

    - by metredigm
    I'm having issues with the depth components of my shadowmapping shaders. The shadow map rendering shader is fine, and works very well. The world rendering shader is more problematic. The only value which seems to definitely be off is the pixel's position from the light's perspective, which I pass in parallel to the position. struct Pixel { float4 position : SV_Position; float4 light_pos : TEXCOORD2; float3 normal : NORMAL; float2 texcoord : TEXCOORD; }; The reason that I used the semantic 'TEXCOORD2' on the light's pixel position is because I believe that the problem lies with Direct3D's interpolation of values between shaders, and I started trying random semantics and also forcing linear and noperspective interpolations. In the world rendering shader, I observed in the pixel shader that the Z value of light_pos was always extremely close to, but less than the W value. This resulted in a depth result of 0.999 or similar for every pixel. Here is the vertex shader code : struct Vertex { float3 position : POSITION; float3 normal : NORMAL; float2 texcoord : TEXCOORD; }; struct Pixel { float4 position : SV_Position; float4 light_pos : TEXCOORD2; float3 normal : NORMAL; float2 texcoord : TEXCOORD; }; cbuffer Camera : register (b0) { matrix world; matrix view; matrix projection; }; cbuffer Light : register (b1) { matrix light_world; matrix light_view; matrix light_projection; }; Pixel RenderVertexShader(Vertex input) { Pixel output; output.position = mul(float4(input.position, 1.0f), world); output.position = mul(output.position, view); output.position = mul(output.position, projection); output.world_pos = mul(float4(input.position, 1.0f), world); output.world_pos = mul(output.world_pos, light_view); output.world_pos = mul(output.world_pos, light_projection); output.texcoord = input.texcoord; output.normal = input.normal; return output; } I suspect interpolation to be the culprit, as I used the camera matrices in place of the light matrices in the vertex shader, and had the same problem. The problem is evident as both of the same vectors were passed to a pixel from the VS, but only one of them showed a change in the PS. I have already thoroughly debugged the matrices' validity, the cbuffers' validity, and the multiplicative validity. I'm very stumped and have been trying to solve this for quite some time. Misc info : The light projection matrix and the camera projection matrix are the same, generated from D3DXMatrixPerspectiveFovLH(), with an FOV of 60.0f * 3.141f / 180.0f, a near clipping plane of 0.1f, and a far clipping plane of 1000.0f. Any ideas on what is happening? (This is a repost from my question on Stack Overflow)

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  • MySQL for Excel new features (1.2.0): Save and restore Edit sessions

    - by Javier Rivera
    Today we are going to talk about another new feature included in the latest MySQL for Excel release to date (1.2.0) which can be Installed directly from our MySQL Installer downloads page.Since the first release you were allowed to open a session to directly edit data from a MySQL table at Excel on a worksheet and see those changes reflected immediately on the database. You were also capable of opening multiple sessions to work with different tables at the same time (when they belong to the same schema). The problem was that if for any reason you were forced to close Excel or the Workbook you were working on, you had no way to save the state of those open sessions and to continue where you left off you needed to reopen them one by one. Well, that's no longer a problem since we are now introducing a new feature to save and restore active Edit sessions. All you need to do is in click the options button from the main MySQL for Excel panel:  And make sure the Edit Session Options (highlighted in yellow) are set correctly, specially that Restore saved Edit sessions is checked: Then just begin an Edit session like you would normally do, select the connection and schema on the main panel and then select table you want to edit data from and click over Edit MySQL Data. and just import the MySQL data into Excel:You can edit data like you always did with the previous version. To test the save and restore saved sessions functionality, first we need to save the workbook while at least one Edit session is opened and close the file.Then reopen the workbook. Depending on your version of Excel is where the next steps are going to differ:Excel 2013 extra step (first): In Excel 2013 you first need to open the workbook with saved edit sessions, then click the MySQL for Excel Icon on the the Data menu (notice how in this version, every time you open or create a new file the MySQL for Excel panel is closed in the new window). Please note that if you work on Excel 2013 with several workbooks with open edit sessions each at the same time, you'll need to repeat this step each time you open one of them: Following steps:  In Excel 2010 or previous, you just need to make sure the MySQL for Excel panel is already open at this point, if its not, please do the previous step specified above (Excel 2013 extra step). For Excel 2010 or older versions you will only need to do this previous step once.  When saved sessions are detected, you will be prompted what to do with those sessions, you can click Restore to continue working where you left off, click Discard to delete the saved sessions (All edit session information for this file will be deleted from your computer, so you will no longer be prompted the next time you open this same file) or click Nothing to continue without opening saved sessions (This will keep the saved edit sessions intact, to be prompted again about them the next time you open this workbook): And there you have it, now you will be able to save your Edit sessions, close your workbook or turn off your computer and you will still be able to reopen them in the future, to continue working right where you were. Today we talked about how you can save your active Edit sessions and restore them later, this is another feature included in the latest MySQL for Excel release (1.2.0). Please remember you can try this product and many others for free downloading the installer directly from our MySQL Installer downloads page.Happy editing !

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  • Creating a voxel world with 3D arrays using threads

    - by Sean M.
    I am making a voxel game (a bit like Minecraft) in C++(11), and I've come across an issue with creating a world efficiently. In my program, I have a World class, which holds a 3D array of Region class pointers. When I initialize the world, I give it a width, height, and depth so it knows how large of a world to create. Each Region is split up into a 32x32x32 area of blocks, so as you may guess, it takes a while to initialize the world once the world gets to be above 8x4x8 Regions. In order to alleviate this issue, I thought that using threads to generate different levels of the world concurrently would make it go faster. Having not used threads much before this, and being still relatively new to C++, I'm not entirely sure how to go about implementing one thread per level (level being a xz plane with a height of 1), when there is a variable number of levels. I tried this: for(int i = 0; i < height; i++) { std::thread th(std::bind(&World::load, this, width, height, depth)); th.join(); } Where load() just loads all Regions at height "height". But that executes the threads one at a time (which makes sense, looking back), and that of course takes as long as generating all Regions in one loop. I then tried: std::thread t1(std::bind(&World::load, this, w, h1, h2 - 1, d)); std::thread t2(std::bind(&World::load, this, w, h2, h3 - 1, d)); std::thread t3(std::bind(&World::load, this, w, h3, h4 - 1, d)); std::thread t4(std::bind(&World::load, this, w, h4, h - 1, d)); t1.join(); t2.join(); t3.join(); t4.join(); This works in that the world loads about 3-3.5 times faster, but this forces the height to be a multiple of 4, and it also gives the same exact VAO object to every single Region, which need individual VAOs in order to render properly. The VAO of each Region is set in the constructor, so I'm assuming that somehow the VAO number is not thread safe or something (again, unfamiliar with threads). So basically, my question is two one-part: How to I implement a variable number of threads that all execute at the same time, and force the main thread to wait for them using join() without stopping the other threads? How do I make the VAO objects thread safe, so when a bunch of Regions are being created at the same time across multiple threads, they don't all get the exact same VAO? Turns out it has to do with GL contexts not working across multiple threads. I moved the VAO/VBO creation back to the main thread. Fixed! Here is the code for block.h/.cpp, region.h/.cpp, and CVBObject.h/.cpp which controls VBOs and VAOs, in case you need it. If you need to see anything else just ask. EDIT: Also, I'd prefer not to have answers that are like "you should have used boost". I'm trying to do this without boost to get used to threads before moving onto other libraries.

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  • Dependency Injection Introduction

    - by MarkPearl
    I recently was going over a great book called “Dependency Injection in .Net” by Mark Seeman. So far I have really enjoyed the book and would recommend anyone looking to get into DI to give it a read. Today I thought I would blog about the first example Mark gives in his book to illustrate some of the benefits that DI provides. The ones he lists are Late binding Extensibility Parallel Development Maintainability Testability To illustrate some of these benefits he gives a HelloWorld example using DI that illustrates some of the basic principles. It goes something like this… class Program { static void Main(string[] args) { var writer = new ConsoleMessageWriter(); var salutation = new Salutation(writer); salutation.Exclaim(); Console.ReadLine(); } } public interface IMessageWriter { void Write(string message); } public class ConsoleMessageWriter : IMessageWriter { public void Write(string message) { Console.WriteLine(message); } } public class Salutation { private readonly IMessageWriter _writer; public Salutation(IMessageWriter writer) { _writer = writer; } public void Exclaim() { _writer.Write("Hello World"); } }   If you had asked me a few years ago if I had thought this was a good approach to solving the HelloWorld problem I would have resounded “No”. How could the above be better than the following…. class Program { static void Main(string[] args) { Console.WriteLine("Hello World"); Console.ReadLine(); } }  Today, my mind-set has changed because of the pain of past programs. So often we can look at a small snippet of code and make judgements when we need to keep in mind that we will most probably be implementing these patterns in projects with hundreds of thousands of lines of code and in projects that we have tests that we don’t want to break and that’s where the first solution outshines the latter. Let’s see if the first example achieves some of the outcomes that were listed as benefits of DI. Could I test the first solution easily? Yes… We could write something like the following using NUnit and RhinoMocks… [TestFixture] public class SalutationTests { [Test] public void ExclaimWillWriteCorrectMessageToMessageWriter() { var writerMock = MockRepository.GenerateMock<IMessageWriter>(); var sut = new Salutation(writerMock); sut.Exclaim(); writerMock.AssertWasCalled(x => x.Write("Hello World")); } }   This would test the existing code fine. Let’s say we then wanted to extend the original solution so that we had a secure message writer. We could write a class like the following… public class SecureMessageWriter : IMessageWriter { private readonly IMessageWriter _writer; private readonly string _secretPassword; public SecureMessageWriter(IMessageWriter writer, string secretPassword) { _writer = writer; _secretPassword = secretPassword; } public void Write(string message) { if (_secretPassword == "Mark") { _writer.Write(message); } else { _writer.Write("Unauthenticated"); } } }   And then extend our implementation of the program as follows… class Program { static void Main(string[] args) { var writer = new SecureMessageWriter(new ConsoleMessageWriter(), "Mark"); var salutation = new Salutation(writer); salutation.Exclaim(); Console.ReadLine(); } }   Our application has now been successfully extended and yet we did very little code change. In addition, our existing tests did not break and we would just need add tests for the extended functionality. Would this approach allow parallel development? Well, I am in two camps on parallel development but with some planning ahead of time it would allow for it as you would simply need to decide on the interface signature and could then have teams develop different sections programming to that interface. So,this was really just a quick intro to some of the basic concepts of DI that Mark introduces very successfully in his book. I am hoping to blog about this further as I continue through the book to list some of the more complex implementations of containers.

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  • Cloud Adoption Challenges

    - by Herve Roggero
    Originally posted on: http://geekswithblogs.net/hroggero/archive/2013/11/07/cloud-adoption-challenges.aspxWhile cloud computing makes sense for most organizations and countless projects, I have seen customers significantly struggle with cloud adoption challenges. This blog post is not an attempt to provide a generic assessment of cloud adoption; rather it is an account of personal experiences in the field, some of which may or may not apply to your organization. Cloud First, Burst? In the rush to cloud adoption some companies have made the decision to redesign their core system with a cloud first approach. However a cloud first approach means that the system may not work anymore on-premises after it has been redesigned, specifically if the system depends on Platform as a Service (PaaS) components (such as Azure Tables). While PaaS makes sense when your company is in a position to adopt the cloud exclusively, it can be difficult to leverage with systems that need to work in different clouds or on-premises. As a result, some companies are starting to rethink their cloud strategy by designing for on-premises first, and modify only the necessary components to burst when needed in the cloud. This generally means that the components need to work equally well in any environment, which requires leveraging Infrastructure as a Service (IaaS) or additional investments for PaaS applications, or both.  What’s the Problem? Although most companies can benefit from cloud computing, not all of them can clearly identify a business reason for doing so other than in very generic terms. I heard many companies claim “it’s cheaper”, or “it allows us to scale”, without any specific metric or clear strategy behind the adoption decision. Other companies have a very clear strategy behind cloud adoption and can precisely articulate business benefits, such as “we have a 500% increase in traffic twice a year, so we need to burst in the cloud to avoid doubling our network and server capacity”. Understanding the problem being solved through by adopting cloud computing can significantly help organizations determine the optimum path and timeline to adoption. Performance or Scalability? I stopped counting the number of times I heard “the cloud doesn’t scale; our database runs faster on a laptop”.  While performance and scalability are related concepts, they are nonetheless different in nature. Performance is a measure of response time under a given load (meaning with a specific number of users), while scalability is the performance curve over various loads. For example one system could see great performance with 100 users, but timeout with 1,000 users, in which case the system wouldn’t scale. However another system could have average performance with 100 users, but display the exact same performance with 1,000,000 users, in which case the system would scale. Understanding that cloud computing does not usually provide high performance, but instead provides the tools necessary to build a scalable system (usually using PaaS services such as queuing and data federation), is fundamental to proper cloud adoption. Uptime? Last but not least, you may want to read the Service Level Agreement of your cloud provider in detail if you haven’t done so. If you are expecting 99.99% uptime annually you may be in for a surprise. Depending on the component being used, there may be no associated SLA at all! Other components may be restarted at any time, or services may experience failover conditions weekly ( or more) based on current overall conditions of the cloud service provider, most of which are outside of your control. As a result, for PaaS cloud environments (and to a certain extent some IaaS systems), applications need to assume failure and gracefully retry to be successful in the cloud in order to provide service continuity to end users. About Herve Roggero Herve Roggero, Windows Azure MVP, is the founder of Blue Syntax Consulting (http://www.bluesyntax.net). Herve's experience includes software development, architecture, database administration and senior management with both global corporations and startup companies. Herve holds multiple certifications, including an MCDBA, MCSE, MCSD. He also holds a Master's degree in Business Administration from Indiana University. Herve is the co-author of "PRO SQL Azure" and “PRO SQL Server 2012 Practices” from Apress, a PluralSight author, and runs the Azure Florida Association.

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  • How to introduce a computer illiterate 50-year old to programming [closed]

    - by sunday
    The other day my dad asked me a question that I would have never expected from him. "How can I learn C++?" My dad is turning 56 this year and computers are a distant concept for him. He doesn't know how to use a phone very well besides calling numbers (no speed dial or contacts); though he has started to learn computers a little better - to the point that he knows how to open the internet (in Windows) and browse around (and has successfully completed several job applications entirely on his own online, of which he was offered positions too). But still, these are too narrow-windowed experiences to mean much, really. While he may not have the background, my dad knows how to read. And I mean reading as a skill, not just an ability. He has little to no college education (financial problems, family, etc.) and was fortunate enough to finish high school, but still taught himself to become a master electrician and has been one for almost 30 years now. He did the same with guitar, learning to play at a very professional level and has been praised for his skill. In high school, he picked up a weight lifting book - and was the only person in his high school at the time to qualify officially as an "athlete" by national standards. In all cases, he just needed something to read. Something to teach him. He absorbs information like a sponge. I have no doubt in my dad's motivation or capability of doing this, so my general goal is simply: Get my dad into the world of computers, and get him on the road to programming. I strongly believe that once I get him through the fundamentals, his drive and reading skill will keep him going on this own. So I'm asking you all: where should I start with all this? And what are the best resources out there? Should I get him to start Linux instead of Windows? Is C++ a bad idea? Remember, he needs to (IMO) learn computers first, and then get that first grasp (the "Hello world" experience) of programming. For money's sake and at top preference, I'd like free online resources that he can read, but by all means any good suggestions in print or paid-for-online are welcome (that I could possibly look into later to purchase). And also, I intend to start him off with C++ (no Python, Java, etc.), because I know it the best and will be able to help him along the way with code. (I have minimal knowledge right now in other languages). Edit: I'm getting a lot of persistent suggestions to use Python. The only reason I wanted to do C++ is that I KNOW it and can be THERE when my dad needs help. My VERY FIRST exposure to programming ever was Java. I learned Java, and I got good at it. I open to other suggestions, but please provide an effective application of your suggestions. EDIT #2: I understand my approach/thinking/knowledge could be lacking here. I'm a sophomore level undergraduate CS major. If you don't agree with anything in my post, tell me why - give me ideas, information - that's why I'm asking in the first place. To narrow down my general goal to specific reachable goals.

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  • Is there any kind of established architecture for browser based games?

    - by black_puppydog
    I am beginning the development of a broser based game in which players take certain actions at any point in time. Big parts of gameplay will be happening in real life and just have to be entered into the system. I believe a good kind of comparison might be a platform for managing fantasy football, although I have virtually no experience playing that, so please correct me if I am mistaken here. The point is that some events happen in the program (i.e. on the server, out of reach for the players) like pulling new results from some datasource, starting of a new round by a game master and such. Other events happen in real life (two players closing a deal on the transfer of some team member or whatnot - again: have never played fantasy football) and have to be entered into the system. The first part is pretty easy since the game masters will be "staff" and thus can be trusted to a certain degree to not mess with the system. But the second part bothers me quite a lot, especially since the actions may involve multiple steps and interactions with different players, like registering a deal with the system that then has to be approved by the other party or denied and passed on to a game master to decide. I would of course like to separate the game logic as far as possible from the presentation and basic form validation but am unsure how to do this in a clean fashion. Of course I could (and will) put some effort into making my own architectural decisions and prototype different ideas. But I am bound to make some stupid mistakes at some point, so I would like to avoid some of that by getting a little "book smart" beforehand. So the question is: Is there any kind of architectural works that I can read up on? Papers, blogs, maybe design documents or even source code? Writing this down this seems more like a business application with business rules, workflows and such... Any good entry points for that? EDIT: After reading the first answers I am under the impression of having made a mistake when including the "MMO" part into the title. The game will not be all fancy (i.e. 3D or such) on the client side and the logic will completely exist on the server. That is, apart from basic form validation for the user which will also be mirrored on the server side. So the target toolset will be HTML5, JavaScript, probably JQuery(UI). My question is more related to the software architecture/design of a system that enforces certain rules. Separation of ruleset and presentation One problem I am having is that I want to separate the game rules from the presentation. The first step would be to make an own module for the game "engine" that only exposes an interface that allows all actions to be taken in a clean way. If an action fails with regard to some pre/post condition, the engine throws an exception which is then presented to the user like "you cannot sell something you do not own" or "after that you would end up in a situation which is not a valid game state." The problem here is that I would like to be able to not even present invalid action in the first place or grey out the corresponding UI elements. Changing and tweaking the ruleset Another big thing is the ruleset. It will probably evolve over time and most definitely must be tweaked. What's more, it should be possible (to a certain extent) to build a ruleset that fits a specific game round, i.e. choosing different kinds of behaviours in different aspects of the game. This would do something like "we play it with extension A today but we throw out extension B." For me, this screams "Architectural/Design pattern" but I have no idea on who might have published on something like this, not even what to google for.

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  • Reading graph inputs for a programming puzzle and then solving it

    - by Vrashabh
    I just took a programming competition question and I absolutely bombed it. I had trouble right at the beginning itself from reading the input set. The question was basically a variant of this puzzle http://codercharts.com/puzzle/evacuation-plan but also had an hour component in the first line(say 3 hours after start of evacuation). It reads like this This puzzle is a tribute to all the people who suffered from the earthquake in Japan. The goal of this puzzle is, given a network of road and locations, to determine the maximum number of people that can be evacuated. The people must be evacuated from evacuation points to rescue points. The list of road and the number of people they can carry per hour is provided. Input Specifications Your program must accept one and only one command line argument: the input file. The input file is formatted as follows: the first line contains 4 integers n r s t n is the number of locations (each location is given by a number from 0 to n-1) r is the number of roads s is the number of locations to be evacuated from (evacuation points) t is the number of locations where people must be evacuated to (rescue points) the second line contains s integers giving the locations of the evacuation points the third line contains t integers giving the locations of the rescue points the r following lines contain to the road definitions. Each road is defined by 3 integers l1 l2 width where l1 and l2 are the locations connected by the road (roads are one-way) and width is the number of people per hour that can fit on the road Now look at the sample input set 5 5 1 2 3 0 3 4 0 1 10 0 2 5 1 2 4 1 3 5 2 4 10 The 3 in the first line is the additional component and is defined as the number of hours since the resuce has started which is 3 in this case. Now my solution was to use Dijisktras algorithm to find the shortest path between each of the rescue and evac nodes. Now my problem started with how to read the input set. I read the first line in python and stored the values in variables. But then I did not know how to store the values of the distance between the nodes and what DS to use and how to input it to say a standard implementation of dijikstras algorithm. So my question is two fold 1.) How do I take the input of such problems? - I have faced this problem in quite a few competitions recently and I hope I can get a simple code snippet or an explanation in java or python to read the data input set in such a way that I can input it as a graph to graph algorithms like dijikstra and floyd/warshall. Also a solution to the above problem would also help. 2.) How to solve this puzzle? My algorithm was: Find shortest path between evac points (in the above example it is 14 from 0 to 3) Multiply it by number of hours to get maximal number of saves Also the answer given for the variant for the input set was 24 which I dont understand. Can someone explain that also. UPDATE: I get how the answer is 14 in the given problem link - it seems to be just the shortest path between node 0 and 3. But with the 3 hour component how is the answer 24 UPDATE I get how it is 24 - its a complete graph traversal at every hour and this is how I solve it Hour 1 Node 0 to Node 1 - 10 people Node 0 to Node 2- 5 people TotalRescueCount=0 Node 1=10 Node 2= 5 Hour 2 Node 1 to Node 3 = 5(Rescued) Node 2 to Node 4 = 5(Rescued) Node 0 to Node 1 = 10 Node 0 to Node 2 = 5 Node 1 to Node 2 = 4 TotalRescueCount = 10 Node 1 = 10 Node 2= 5+4 = 9 Hour 3 Node 1 to Node 3 = 5(Rescued) Node 2 to Node 4 = 5+4 = 9(Rescued) TotalRescueCount = 9+5+10 = 24 It hard enough for this case , for multiple evac and rescue points how in the world would I write a pgm for this ?

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  • Why is 0 false?

    - by Morwenn
    This question may sound dumb, but why does 0 evaluates to false and any other [integer] value to true is most of programming languages? String comparison Since the question seems a little bit too simple, I will explain myself a little bit more: first of all, it may seem evident to any programmer, but why wouldn't there be a programming language - there may actually be, but not any I used - where 0 evaluates to true and all the other [integer] values to false? That one remark may seem random, but I have a few examples where it may have been a good idea. First of all, let's take the example of strings three-way comparison, I will take C's strcmp as example: any programmer trying C as his first language may be tempted to write the following code: if (strcmp(str1, str2)) { // Do something... } Since strcmp returns 0 which evaluates to false when the strings are equal, what the beginning programmer tried to do fails miserably and he generally does not understand why at first. Had 0 evaluated to true instead, this function could have been used in its most simple expression - the one above - when comparing for equality, and the proper checks for -1 and 1 would have been done only when needed. We would have considered the return type as bool (in our minds I mean) most of the time. Moreover, let's introduce a new type, sign, that just takes values -1, 0 and 1. That can be pretty handy. Imagine there is a spaceship operator in C++ and we want it for std::string (well, there already is the compare function, but spaceship operator is more fun). The declaration would currently be the following one: sign operator<=>(const std::string& lhs, const std::string& rhs); Had 0 been evaluated to true, the spaceship operator wouldn't even exist, and we could have declared operator== that way: sign operator==(const std::string& lhs, const std::string& rhs); This operator== would have handled three-way comparison at once, and could still be used to perform the following check while still being able to check which string is lexicographically superior to the other when needed: if (str1 == str2) { // Do something... } Old errors handling We now have exceptions, so this part only applies to the old languages where no such thing exist (C for example). If we look at C's standard library (and POSIX one too), we can see for sure that maaaaany functions return 0 when successful and any integer otherwise. I have sadly seen some people do this kind of things: #define TRUE 0 // ... if (some_function() == TRUE) { // Here, TRUE would mean success... // Do something } If we think about how we think in programming, we often have the following reasoning pattern: Do something Did it work? Yes -> That's ok, one case to handle No -> Why? Many cases to handle If we think about it again, it would have made sense to put the only neutral value, 0, to yes (and that's how C's functions work), while all the other values can be there to solve the many cases of the no. However, in all the programming languages I know (except maybe some experimental esotheric languages), that yes evaluates to false in an if condition, while all the no cases evaluate to true. There are many situations when "it works" represents one case while "it does not work" represents many probable causes. If we think about it that way, having 0 evaluate to true and the rest to false would have made much more sense. Conclusion My conclusion is essentially my original question: why did we design languages where 0 is false and the other values are true, taking in account my few examples above and maybe some more I did not think of? Follow-up: It's nice to see there are many answers with many ideas and as many possible reasons for it to be like that. I love how passionate you seem to be about it. I originaly asked this question out of boredom, but since you seem so passionate, I decided to go a little further and ask about the rationale behind the Boolean choice for 0 and 1 on Math.SE :)

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  • find substring and indices in mips

    - by ccc
    im trying find out substring and first occurrence indices. but something wrong. im comparing each element of pattern array and each element of string array until pointer reach to '\0'. and if any characater found it keep in temp array. and increasing pointers +1. whats the problem. algorithm is totaly wrong ? #Note: $v0 is a symbolic name used by the assember for $2. # $a0 is a symbolic name used by the assember for $4. .data prompt_str: .asciiz "Please type a text string: " prompt_ptr: .asciiz "Please type a pattern string: " print_yes: .asciiz "Yes, there is a match." print_no: .asciiz "No, there is no match." text_str: .asciiz "Text string : " pattern_str: .asciiz "Pattern string : " print_out: .asciiz "Output to be produced :" print_dash: .asciiz "----------------------" print_index: .asciiz "Starting index :" print_msg : .asciiz "Length of longest partial match = " nl: .asciiz "\n" str : .space 81 ptr : .space 81 tmp : .space 81 .text main: la $a0, prompt_str li $v0, 4 #print_string command. syscall la $a0,str #read string li $a1,81 li $v0,8 syscall la $t0,str #move string to $t0 la $a0,prompt_ptr li $v0,4 #print pattern command syscall la $a0,ptr #read pattern li $a1,81 li $v0,8 syscall la $t1,ptr #move pattern to $t1 la $t5,tmp #move temp to $t5 lb $t2,0($t0) #pointer first element array of string lb $t3,0($t1) #pointer first element array of pattern lb $t6,0($t5) #pointer first element array of temp loop : beq $t3,$0,end_loop beq $t2,$t3,match addiu $t0,$t0,1 j loop match : move $t6,$t2 addiu $t5,$t5,1 addiu $t0,$t0,1 addiu $t1,$t1,1 j print_match print_match : la $a0,text_str #print string li $v0,4 syscall move $a0,$t0 li $v0,4 syscall la $a0,nl #print newline character li $v0,4 syscall la $a0,pattern_str #print pattern string li $v0,4 syscall move $a0,$t1 li $v0,4 syscall la $a0,nl #print newline character li $v0,4 syscall la $a0,print_out #print output line and newline character li $v0,4 syscall la $a0,nl li $v0,4 syscall la $a0,print_dash li $v0,4 syscall la $a0,print_yes li $v0,4 syscall la $a0,print_index #print starting index li $v0,4 syscall li $v0,10 syscall end_loop : li $v0,10 syscall

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  • A call to PInvoke function '[...]' has unbalanced the stack

    - by Sanctus2099
    Hey I'm getting this weird error on some stuff I've been using for quite a while. It may be a new thing in Visual Studio 2010 but I'm not sure. I'm trying to call a unamanged function written in C++ from C#. From what I've read on the internet and the error message itself it's got something to do with the fact that the signature in my C# file is not the same as the one from C++ but I really can't see it. First of all this is my unamanged function below: TEngine GCreateEngine(int width,int height,int depth,int deviceType); And here is my function in C#: [DllImport("Engine.dll", EntryPoint = "GCreateEngine", CallingConvention = CallingConvention.StdCall)] public static extern IntPtr CreateEngine(int width,int height,int depth,int device); When I debug into C++ I see all arguments just fine so thus I can only think it's got something to do with transforming from TEngine (which is a pointer to a class named CEngine) to IntPtr. I've used this before in VS2008 with no problem. I hope my problem is clear enough for you guys to understand.

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  • SSRS 2005 - Cascading parameters and default value update problem

    - by sHr0oMaN
    I have a report with cascading parameters. The first parameter is Finanical Period Type, being either Month or Week. The second parameter is a list of either financial months or weeks depending on what was selected for the first parameter. This all works well and selecting a series of different Financial Period Types in sequence correctly updates the second parameter's values. However I now wish to add a default value for the second parameter, which is once again dependent on the first parameter. So I've added an additional field to the dataset populating the second parameter called DefaultPeriod and set the second parameter's default value to be retrieved from the above field. The first time I select the Financial Period Type, the default is correctly set. However changing the Financial Period Type results in an updated list for the second parameter, but the default is incorrect. It remains set to the original default value, even thought the dataset has been refresh and the DefaultPeriod field is correct. This is both an issue in the IDE and on the Report Manager site.

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  • UINavigationController inside tabbar loading a child root view

    - by Doug
    Hi guys, Firstly i'll preface by saying that i am a complete Cocoa touch/objective c noob (.Net dev having a dabble) I have searched on Google as well as here but cannot seem to find an easy solution. I have a UItabbarcontroller view with a UINavigationController inside its first tab I have the root view for this UINavigationController stored in a seperate class and NIB as i am trying to seperate the data viewing from the data loading (i'm going to reuse the table list in multiple places in my database) and simply pass the root view its data using a loading method and have it take it from there. What i want to happen: App loads and loads the first view of the tab bar (A UINavigationController) The UINavigationController inside the first view loads a root view (a UIViewController with a table view) and sets its title The UINavigationController loads the data from a web service and parses it The UINavigationController sends the data to a loading method inside the UIViewController Am i thinking about this completely wrongly? What currently happens: the first tab bar loads with an empty uinavigationcontroller (no table view) the data methods fire and get the webservice data this child view gets sent its data using the loading method the tableview delegate events fail to fire inside the child view telling it to load the data into the table I just can't seem how to load my second view inside the root view of the navigation controller and then send it my data?

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  • Recursion in an ASP.NET MVC view

    - by Dennis Palmer
    I have a nested data object for a set of items within categories. Each category can contain sub categories and there is no set limit to the depth of sub categories. (A file system would have a similar structure.) It looks something like this: class category { public int id; public string name; public IQueryable<category> categories; public IQueryable<item> items; } class item { public int id; public string name; } I am passing a list of categories to my view as IQueryable<category>. I want to output the categories as a set of nested unordered list (<ul>) blocks. I could nest foreach loops, but then the depth of sub categories would be limited by the number of nested foreach blocks. In WinForms, I have done similar processing using recursion to populate a TreeView, but I haven't seen any examples of using recursion within an ASPX MVC view. Can recursion be done within an ASPX view? Are there other view engines that include recursion for view output?

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  • jQuery .each() with multiple selectors - skip, then .empty() elements

    - by joe
    I'd like to remove all matching elements, but skip the first instance of each match: // Works as expected: removes all but first instance of .a jQuery ('.a', '#scope') .each ( function (i) { if (i > 0) jQuery (this).empty(); }); // Expected: removal of all but first instance of .a and .b // Result: removal of *all* instances of both .a and .b jQuery ('.a, .b', '#scope') .each ( function (i) { if (i > 1) jQuery (this).empty(); }); <div id="scope"> <!-- Want to keep the first instance of .a and .b --> <div class="a">[bla]</span> <div class="b">[bla]</span> <!-- Want to remove all the others --> <div class="a">[bla]</span> <div class="b">[bla]</span <div class="a">[bla]</span> <div class="b">[bla]</span ... </div> Any suggestions? Using jQuery() rather than $() because of conflict with 'legacy' code Using .empty() because .a contains JS I'd like to disable Stuck with jQuery 1.2.3 Thanks you!

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  • How to call RequiredFieldValidator on client before postback

    - by Si
    I've inherited some code which breaks a page up into tabs using divs. On the first page there are many required field and regex validators. The problem is a user can switch to another tab, trigger a postback and fail the validators on the first page, leaving things in a mess. What I want to be able to do is perform the validation on the first page as a user selects another tab, thus preventing them from moving to a new tab until the first page is valid. <ul> <li><a href="#tab1">Tab 1</a> </li> <li><a href="#tab2" onclick="return isValid();">Tab 2</a></li> <li><a href="#tab3" onclick="return isValid();">Tab 3</a></li> </ul> Where isValid needs to fire off the validators. Thanks!

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  • solve a classic map-reduce problem with opencl?

    - by liuliu
    I am trying to parallel a classic map-reduce problem (which can parallel well with MPI) with OpenCL, namely, the AMD implementation. But the result bothers me. Let me brief about the problem first. There are two type of data that flow into the system: the feature set (30 parameters for each) and the sample set (9000+ dimensions for each). It is a classic map-reduce problem in the sense that I need to calculate the score of every feature on every sample (Map). And then, sum up the overall score for every feature (Reduce). There are around 10k features and 30k samples. I tried different ways to solve the problem. First, I tried to decompose the problem by features. The problem is that the score calculation consists of random memory access (pick some of the 9000+ dimensions and do plus/subtraction calculations). Since I cannot coalesce memory access, it costs. Then, I tried to decompose the problem by samples. The problem is that to sum up overall score, all threads are competing for few score variables. It keeps overwriting the score which turns out to be incorrect. (I cannot carry out individual score first and sum up later because it requires 10k * 30k * 4 bytes). The first method I tried gives me the same performance on i7 860 CPU with 8 threads. However, I don't think the problem is unsolvable: it is remarkably similar to ray tracing problem (for which you carry out calculation that millions of rays against millions of triangles). Any ideas?

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