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  • Isometric smooth fog

    - by marcg11
    I'm working on a simple 2d game with direct3d 9. It's a isometric game with diamond tiles and a staggered map. This is what I have: As you se I have some king of fog which is acomplished by having a fog matrix which is true (clear terrain) or false (obscure terran). But the result is very chunky. The fog moves as the player moves by tiles but not by pixels. Basically I check for every tile if there is fog, if so I just change the color of that tile: if(scene->fog[i+mapx][j+mapy] == FOG_NONE) { tile_color = 0x666666FF; } I also would like the fog to be smoother, for that I followed this "tutorial" but I haven't managed to work it it out. http://www.appsizematters.com/2010/07/how-to-implement-a-fog-of-war-part-2-smooth/

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  • Are unit tests really used as documentation?

    - by stijn
    I cannot count the number of times I read statements in the vein of 'unit tests are a very important source of documentation of the code under test'. I do not deny they are true. But personally I haven't found myself using them as documentation, ever. For the typical frameworks I use, the method declarations document their behaviour and that's all I need. And I assume the unit tests backup everything stated in that documentation, plus likely some more internal stuff, so on one side it duplicates the ducumentation while on the other it might add some more that is irrelevant. So the question is: when are unit tests used as documentation? When the comments do not cover everything? By developpers extending the source? And what do they expose that can be useful and relevant that the documentation itself cannot expose?

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  • Keyboard Navigation For ASP.NET GridView And TreeList Controls v2010 vol 1

    Great new keyboard navigation feature! With the DXperience v2010.1 release, you can enable keyboard navigation by changing a single property, set KeyboardSupport to true. Once KeyboardSupport is enabled, your users can: Focus On Grid Using Control Activation Key Specify an access key for your grid controls and allow your end-users to press CTRL+SHIFT+AccessKey to change focus to the corresponding grid control. Focused Row Press the UP and DOWN arrow keys to move row focus....Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Didmo did mo' to advance Java ME technology than other companies

    - by hinkmond
    Here's a company that's keeping Java ME tech real in the field. DIDMO is the creator of Magmito, a user-generated mobile content creation service. That's a good thing to have when there are so many mobile platforms out there to choose from. See: Didmo does mo' Here's a quote: DIDMO's mission is to deliver the market leading mobile application generator. We will achieve this by meeting the growing market demand for a true end-to-end solution for easy mobile content creation and universal delivery. Our software offering will incorporate an award- winning toolset with universal reach (from Java to [that other platform]), Make an app today! Just make sure it's a Java ME app... Hinkmond

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  • WMemoryProfiler is Released

    - by Alois Kraus
    What is it? WMemoryProfiler is a managed profiling Api to aid integration testing. This free library can get managed heap statistics and memory usage for your own process (remember testing) and other processes as well. The best thing is that it does work from .NET 2.0 up to .NET 4.5 in x86 and x64. To make it more interesting it can attach to any running .NET process. The reason why I do mention this is that commercial profilers do support this functionality only for their professional editions. An normally only since .NET 4.0 since the profiling API only since then does support attaching to a running process. This thing does differ in many aspects from “normal” profilers because while profiling yourself you can get all objects from all managed heaps back as an object array. If you ever wanted to change the state of an object which does only exist a method local in another thread you can get your hands on it now … Enough theory. Show me some code /// <summary> /// Show feature to not only get statisics out of a process but also the newly allocated /// instances since the last call to MarkCurrentObjects. /// GetNewObjects does return the newly allocated objects as object array /// </summary> static void InstanceTracking() { using (var dumper = new MemoryDumper()) // if you have problems use to see the debugger windows true,true)) { dumper.MarkCurrentObjects(); Allocate(); ILookup<Type, object> newObjects = dumper.GetNewObjects() .ToLookup( x => x.GetType() ); Console.WriteLine("New Strings:"); foreach (var newStr in newObjects[typeof(string)] ) { Console.WriteLine("Str: {0}", newStr); } } } … New Strings: Str: qqd Str: String data: Str: String data: 0 Str: String data: 1 … This is really hot stuff. Not only you can get heap statistics but you can directly examine the new objects and make queries upon them. When I do find more time I can reconstruct the object root graph from it from my own process. It this cool or what? You can also peek into the Finalization Queue to check if you did accidentally forget to dispose a whole bunch of objects … /// <summary> /// .NET 4.0 or above only. Get all finalizable objects which are ready for finalization and have no other object roots anymore. /// </summary> static void NotYetFinalizedObjects() { using (var dumper = new MemoryDumper()) { object[] finalizable = dumper.GetObjectsReadyForFinalization(); Console.WriteLine("Currently {0} objects of types {1} are ready for finalization. Consider disposing them before.", finalizable.Length, String.Join(",", finalizable.ToLookup( x=> x.GetType() ) .Select( x=> x.Key.Name)) ); } } How does it work? The W of WMemoryProfiler is a good hint. It does employ Windbg and SOS dll to do the heavy lifting and concentrates on an easy to use Api which does hide completely Windbg. If you do not want to see Windbg you will never see it. In my experience the most complex thing is actually to download Windbg from the Windows 8 Stanalone SDK. This is described in the Readme and the exception you are greeted with if it is missing in much greater detail. So I will not go into this here.   What Next? Depending on the feedback I do get I can imagine some features which might be useful as well Calculate first order GC Roots from the actual object graph Identify global statics in Types in object graph Support read out of finalization queue of .NET 2.0 as well. Support Memory Dump analysis (again a feature only supported by commercial profilers in their professional editions if it is supported at all) Deserialize objects from a memory dump into a live process back (this would need some more investigation but it is doable) The last item needs some explanation. Why on earth would you want to do that? The basic idea is to store in your live process some logging/tracing data which can become quite big but since it is never written to it is very fast to generate. When your process crashes with a memory dump you could transfer this data structure back into a live viewer which can then nicely display your program state at the point it did crash. This is an advanced trouble shooting technique I have not seen anywhere yet but it could be quite useful. You can have here a look at the current feature list of WMemoryProfiler with some examples.   How To Get Started? First I would download the released source package (it is tiny). And compile the complete project. Then you can compile the Example project (it has this name) and uncomment in the main method the scenario you want to check out. If you are greeted with an exception it is time to install the Windows 8 Standalone SDK which is described in great detail in the exception text. Thats it for the first round. I have seen something more limited in the Java world some years ago (now I cannot find the link anymore) but anyway. Now we have something much better.

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  • Why distance field text rendering have clear outline?

    - by jinhwan
    http://www.valvesoftware.com/publications/2007/SIGGRAPH2007_AlphaTestedMagnification.pdf All the process for doing distance rendering is clear, but 'how does it work' is not clear for me. It looks like that distance field pixels which are created around original pixel may affect 2d texture sampling interpolation process. But I can't understand the interpolation process. I've read that the distance field rendering is processed under nearest-neighbour interpolation. If it is true, shouldn't the distance field redering creates non interpolated result? In my thought, they should looks liked retro style pixel art. Where do i misunderstand in this process? So far, It is no difference with alpha test for me. Both of them throw away all pixcel which are not in. How does extra distance field pixel affect rendering under nearest-neighbour interpolation?

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  • Optimizing drawing of cubes

    - by Christian Frantz
    After googling for hours I've come to a few conclusions, I need to either rewrite my whole cube class, or figure out how to use hardware instancing. I can draw up to 2500 cubes with little lag, but after that my fps drops. Is there a way I can use my class for hardware instancing? Or would I be better off rewriting my class for optimization? public class Cube { public GraphicsDevice device; public VertexBuffer cubeVertexBuffer; public Cube(GraphicsDevice graphicsDevice) { device = graphicsDevice; var vertices = new List<VertexPositionTexture>(); BuildFace(vertices, new Vector3(0, 0, 0), new Vector3(0, 1, 1)); BuildFace(vertices, new Vector3(0, 0, 1), new Vector3(1, 1, 1)); BuildFace(vertices, new Vector3(1, 0, 1), new Vector3(1, 1, 0)); BuildFace(vertices, new Vector3(1, 0, 0), new Vector3(0, 1, 0)); BuildFaceHorizontal(vertices, new Vector3(0, 1, 0), new Vector3(1, 1, 1)); BuildFaceHorizontal(vertices, new Vector3(0, 0, 1), new Vector3(1, 0, 0)); cubeVertexBuffer = new VertexBuffer(device, VertexPositionTexture.VertexDeclaration, vertices.Count, BufferUsage.WriteOnly); cubeVertexBuffer.SetData<VertexPositionTexture>(vertices.ToArray()); } private void BuildFace(List<VertexPositionTexture> vertices, Vector3 p1, Vector3 p2) { vertices.Add(BuildVertex(p1.X, p1.Y, p1.Z, 1, 0)); vertices.Add(BuildVertex(p1.X, p2.Y, p1.Z, 1, 1)); vertices.Add(BuildVertex(p2.X, p2.Y, p2.Z, 0, 1)); vertices.Add(BuildVertex(p2.X, p2.Y, p2.Z, 0, 1)); vertices.Add(BuildVertex(p2.X, p1.Y, p2.Z, 0, 0)); vertices.Add(BuildVertex(p1.X, p1.Y, p1.Z, 1, 0)); } private void BuildFaceHorizontal(List<VertexPositionTexture> vertices, Vector3 p1, Vector3 p2) { vertices.Add(BuildVertex(p1.X, p1.Y, p1.Z, 0, 1)); vertices.Add(BuildVertex(p2.X, p1.Y, p1.Z, 1, 1)); vertices.Add(BuildVertex(p2.X, p2.Y, p2.Z, 1, 0)); vertices.Add(BuildVertex(p1.X, p1.Y, p1.Z, 0, 1)); vertices.Add(BuildVertex(p2.X, p2.Y, p2.Z, 1, 0)); vertices.Add(BuildVertex(p1.X, p1.Y, p2.Z, 0, 0)); } private VertexPositionTexture BuildVertex(float x, float y, float z, float u, float v) { return new VertexPositionTexture(new Vector3(x, y, z), new Vector2(u, v)); } public void Draw(BasicEffect effect) { foreach (EffectPass pass in effect.CurrentTechnique.Passes) { pass.Apply(); device.SetVertexBuffer(cubeVertexBuffer); device.DrawPrimitives(PrimitiveType.TriangleList, 0, cubeVertexBuffer.VertexCount / 3); } } } The following class is a list that draws the cubes. public class DrawableList<T> : DrawableGameComponent { private BasicEffect effect; private ThirdPersonCam camera; private class Entity { public Vector3 Position { get; set; } public Matrix Orientation { get; set; } public Texture2D Texture { get; set; } } private Cube cube; private List<Entity> entities = new List<Entity>(); public DrawableList(Game game, ThirdPersonCam camera, BasicEffect effect) : base(game) { this.effect = effect; cube = new Cube(game.GraphicsDevice); this.camera = camera; } public void Add(Vector3 position, Matrix orientation, Texture2D texture) { entities.Add(new Entity() { Position = position, Orientation = orientation, Texture = texture }); } public override void Draw(GameTime gameTime) { foreach (var item in entities) { effect.VertexColorEnabled = false; effect.TextureEnabled = true; effect.Texture = item.Texture; Matrix center = Matrix.CreateTranslation(new Vector3(-0.5f, -0.5f, -0.5f)); Matrix scale = Matrix.CreateScale(1f); Matrix translate = Matrix.CreateTranslation(item.Position); effect.World = center * scale * translate; effect.View = camera.view; effect.Projection = camera.proj; effect.FogEnabled = true; effect.FogColor = Color.CornflowerBlue.ToVector3(); effect.FogStart = 1.0f; effect.FogEnd = 50.0f; cube.Draw(effect); } base.Draw(gameTime); } } } There are probably many reasons that my fps is so slow, but I can't seem to figure out how to fix it. I've looked at techcraft as well, but what I have is too specific to what I want the outcome to be to just rewrite everything from scratch

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  • APress Deal of the Day 9/Jan/2011 - Pro Silverlight 3 in VB

    - by TATWORTH
    Today's $10 deal from APress at http://www.apress.com/info/dailydeal is Pro Silverlight 3 in VB Silverlight is a lightweight browser plug-in that frees your code from the traditional confines of the browser. It's a rules-changing, groundbreaking technology that allows you to run rich client applications right inside the browser. Even more impressively, it's able to host true .NET applications in non-Microsoft browsers (like Firefox) and on non-Microsoft platforms (like Mac OS X). Silverlight is still new and evolving fast, and you need a reliable guidebook to make sense of it.

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  • Issue with dynamic Quicklist in Unity

    - by costales
    I would like to add a Quicklist to Gufw app, but it isn't working. The code is here (you can install reading the INSTALL file): http://bazaar.launchpad.net/~gufw-developers/gui-ufw/testing/files/3 I added lines 52-54 to the view (a simple example) from the official API web: http://bazaar.launchpad.net/~gufw-developers/gui-ufw/testing/view/head:/gufw/view/gufw.py https://wiki.ubuntu.com/Unity/LauncherAPI self.launcher = Unity.LauncherEntry.get_for_desktop_id ("gufw.desktop") self.launcher.set_property("progress", 0.42) self.launcher.set_property("progress_visible", True) But nothing happen. But if I run this file with Gufw running: http://bazaar.launchpad.net/~gufw-developers/gui-ufw/testing/view/head:/gufw/test_launcher.py $ python test_launcher.py The progress bar appears! :/ I don't know what am I missing? :P Any idea? Thanks in advance! The environment is Ubuntu 13.04.

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  • Periodic updates of an object in Unity

    - by Blue
    I'm trying to make a collider appear every 1 second. But I can't get the code right. I tried enabling the collider in the Update function and putting a yield to make it update every second or so. But it's not working (it gives me an error: Update() cannot be a coroutine.) How would I fix this? Would I need a timer system to toggle the collider? var waitTime : float = 1; var trigger : boolean = false; function Update () { if(!trigger){ collider.enabled = false; yield WaitForSeconds(waitTime); } if(trigger){ collider.enabled = true; yield WaitForSeconds(waitTime); } } }

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  • How is this recursion properly working when it is iterated through [on hold]

    - by Rakso Zrobin
    Here is my code right now: hasht= {"A":["B", "D", "E"], "B":["C"], "C":["D", "E"], "D":["C", "E"], "E":["B"]} paths=[] def recusive(start, finish, started=true): if start==finish and !started: return start else: for i in hasht[start]: path= start+ recusive(i,finish,false) paths.append(path) print (recusive("C","C",1)) print paths # [CDC, CDEBC, CEBC] I am trying to generate a table like the one on the bottom, but am running into the problem of the string and the array not being able to concatenate. When I just return however, it returns CDC and works, however, exiting the function as return is meant to do. I am wondering how I can improve my code here to (1) make it work, (2) why my logic was faulty. For example, I understand that it generates say [DC], but I am confused as to how to go around that. perhaps index the value returned?

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  • Why do I get an exception when playing multiple sound instances?

    - by Boreal
    Right now, I'm adding a rudimentary sound engine to my game. So far, I am able to load in a WAV file and play it once, then free up the memory when I close the game. However, the game crashes with a nice ArgumentOutOfBoundsException when I try to play another sound instance. Specified argument was out of the range of valid values. Parameter name: readLength I'm following this tutorial pretty much exactly, but I still keep getting the aforementioned error. Here's my sound-related code. /// <summary> /// Manages all sound instances. /// </summary> public static class Audio { static XAudio2 device; static MasteringVoice master; static List<SoundInstance> instances; /// <summary> /// The XAudio2 device. /// </summary> internal static XAudio2 Device { get { return device; } } /// <summary> /// Initializes the audio device and master track. /// </summary> internal static void Initialize() { device = new XAudio2(); master = new MasteringVoice(device); instances = new List<SoundInstance>(); } /// <summary> /// Releases all XA2 resources. /// </summary> internal static void Shutdown() { foreach(SoundInstance i in instances) i.Dispose(); master.Dispose(); device.Dispose(); } /// <summary> /// Registers a sound instance with the system. /// </summary> /// <param name="instance">Sound instance</param> internal static void AddInstance(SoundInstance instance) { instances.Add(instance); } /// <summary> /// Disposes any sound instance that has stopped playing. /// </summary> internal static void Update() { List<SoundInstance> temp = new List<SoundInstance>(instances); foreach(SoundInstance i in temp) if(!i.Playing) { i.Dispose(); instances.Remove(i); } } } /// <summary> /// Loads sounds from various files. /// </summary> internal class SoundLoader { /// <summary> /// Loads a .wav sound file. /// </summary> /// <param name="format">The decoded format will be sent here</param> /// <param name="buffer">The data will be sent here</param> /// <param name="soundName">The path to the WAV file</param> internal static void LoadWAV(out WaveFormat format, out AudioBuffer buffer, string soundName) { WaveStream wave = new WaveStream(soundName); format = wave.Format; buffer = new AudioBuffer(); buffer.AudioData = wave; buffer.AudioBytes = (int)wave.Length; buffer.Flags = BufferFlags.EndOfStream; } } /// <summary> /// Manages the data for a single sound. /// </summary> public class Sound : IAsset { WaveFormat format; AudioBuffer buffer; /// <summary> /// Loads a sound from a file. /// </summary> /// <param name="soundName">The path to the sound file</param> /// <returns>Whether the sound loaded successfully</returns> public bool Load(string soundName) { if(soundName.EndsWith(".wav")) SoundLoader.LoadWAV(out format, out buffer, soundName); else return false; return true; } /// <summary> /// Plays the sound. /// </summary> public void Play() { Audio.AddInstance(new SoundInstance(format, buffer)); } /// <summary> /// Unloads the sound from memory. /// </summary> public void Unload() { buffer.Dispose(); } } /// <summary> /// Manages a single sound instance. /// </summary> public class SoundInstance { SourceVoice source; bool playing; /// <summary> /// Whether the sound is currently playing. /// </summary> public bool Playing { get { return playing; } } /// <summary> /// Starts a new instance of a sound. /// </summary> /// <param name="format">Format of the sound</param> /// <param name="buffer">Buffer holding sound data</param> internal SoundInstance(WaveFormat format, AudioBuffer buffer) { source = new SourceVoice(Audio.Device, format); source.BufferEnd += (s, e) => playing = false; source.Start(); source.SubmitSourceBuffer(buffer); // THIS IS WHERE THE EXCEPTION IS THROWN playing = true; } /// <summary> /// Releases memory used by the instance. /// </summary> internal void Dispose() { source.Dispose(); } } The exception occurs on line 156 when I am playing the sound: source.SubmitSourceBuffer(buffer);

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  • Why can't my Wifi connect or disconnect?

    - by tmy1018
    Wifi connection might drop spontaneously or simply cannot connect. Users on Ubuntu 10.04 and 11.04 have reported experiencing the problem. Running dmesg would show: [210749.637705] wlan0: deauthenticating from 00:23:89:48:3b:b0 by local choice (reason=3) [210778.632244] wlan0: deauthenticating from 00:23:89:48:3b:b0 by local choice (reason=3) [210784.456359] wlan0: deauthenticating from 00:23:89:82:75:70 by local choice (reason=3) which is pretty cryptic. I have tried: kill -9 wpa_supplicant, but wpa_supplicant keeps getting restarted each time. Also, some have suggested that this was caused by enabling power management. However, this might not be true, as the problem has presented itself in a situation where power management was disabled.

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  • Switching to HTTPS - redirect question

    - by seengee
    Following the recent Google announcements about improved ranking for sites running on https we have a number of clients asking about this. Is it safe to just 301 redirect all pages to their SSL equivalent, for example in a common PHP include file: if($_SERVER['HTTPS']!="on"){ $redirect= "https://".$_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI']; header("Location:$redirect",true,301); exit(); } Obviously I'm aware this is also possible within a .htaccess file but that cannot be modified in our case. Obviously all internal links would be switched to https:// links but obviously we need to sort out incoming links from Google and elsewhere. Is this a sound approach? Are there any other gotchas to be aware of?

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  • Building Interactive User Interfaces with Microsoft ASP. ...

    The ASP.NET AJAX UpdatePanel provides a quick and easy way to implement a snappier, AJAX-based user interface in an ASP.NET WebForm. In a nutshell, UpdatePanels allow page developers to refresh selected parts of the page (instead of refreshing the entire page). Typically, an UpdatePanel contains user interface elements that would normally trigger a full page postback - controls like Buttons or DropDownLists that have their <code>AutoPostBack</code> property set to True. Such controls, when placed inside an UpdatePanel, cause a partial page postback to occur. On a partial page postback only the contents of the UpdatePanel are refreshed, avoiding the "flash" of having the entire page reloaded. (For a more in-depth look at the UpdatePanel control, refer back to the

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  • Cannot connect to Internet on 11.04 using BSNL EVDO Prithvi Card

    - by Joy
    I cannot connect to Internet using BSNL EVDO Prithvi data card. Went through some websites that offered help, installed wvdial package and tried again, but was unsuccessful. I have Read that, Ubuntu 11.04 automatically detects Data Card, You only need to configure "Network Manager" and it will work, I did exactly that, but the result is same. The OS detects the data card, and the presence of network , but it cannot login. I have read in some forums that Ubuntu 11.04 does not have support for BSNL EVDO Prithvi, is it true? I re-checked the "User ID" and "Password". Its working on Windows. Please help me fix this.

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  • OpenGL Get Rotated X and Y of quad

    - by matejkramny
    I am developing a game in 2D using LWJGL library. So far I have a rotating box. I have done basic Rectangle collision, but it doesn't work for rotated rectangles. Does OpenGL have a function that returns the vertices of rotated rectangle? Or is there another way of doing this using trigonometry? I had researched how to do this and everything I found was using some matrix that I don't understand so I am asking if there is another way of doing this. For clarification, I am trying to find out the true (rotated) X,Y of each point of the rectangle. Let's say, the first point of a rectangle (top,left) has x=10 y=10.. Width and height is 100 pixels. When I rotate the rectangle using glRotatef() the x and y stay the same. The rotation is happening inside OpenGL. I need to extract the x,y of the rectangle so I can detect collisions properly.

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  • php.ini modifications has no effect on joomla

    - by user488736
    I have a netbook with a recently installed ubuntu server 12.04 64-bit. I have (only) installed Joomla on it (version 2.5) and now I am trying to tweak the php.ini settings so I can install jomsocial onto joomla. I have changed these settings: upload_max_filesize = 2M post_max_size = 8M to this: upload_max_filesize = 20M post_max_size = 20M in all php.ini-files in my system. Thats six files, found using 'locate': /etc/php5/apache2/php.ini /etc/php5/cli/php.ini /usr/share/doc/php5-common/examples/php.ini-development /usr/share/php5/php.ini-production /usr/share/php5/php.ini-production-dist /usr/share/php5/php.ini-production.cli I have double-checked that these files actually contain the new settings. Still, joomla does not recognize the new settings, stating that upload_max_filesize is still only 2M and post_max_size is still only 8M The same is true after a complete restart of the server. What am I doing wrong here?

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  • SSL is not enabled in Heroku

    - by Drom
    Since Heroku has integrated the piggybank_ssl addon by default, trying: heroku addons:add piggyback_ssl or heroku addons:add ssl:piggyback results in: ! This add-on is now a standard Heroku platform feature. ! Your apps can already use piggyback SSL. But, accessing: mywebsite.herokuapp.com results in: SSL is not enabled mywebsite.herokuapp.com does not have SSL enabled. My production.rb has: config.force_ssl = true What am I missing? Update I have read the page SSL on Heroku, but it's obsolete, they suggest to run: heroku addons:add piggyback_ssl Which is no longer necessary. SOLVED ! I don't change anything, and now it's working. It seems that it was a heroku problem.

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  • Rendering transparent textures in directX

    - by Vibhore Tanwer
    I am working with a directX application with WPF, I am facing a problem with videos and images that contains transparent pixels, I have to draw a color in background an then a video/image over it. What I expect is background color should be visible while playing video only non transparent pixels should be visible but what I get is a black background behind the video. I am using following settings on device to achieve alpha blending : device.RenderState.SourceBlend = Blend.SourceAlpha; device.RenderState.DestinationBlend = Blend.InvSourceAlpha; device.RenderState.AlphaBlendEnable = true; What am I missing here? What is the best approach to handle transparent videos? Any help will be of great value to me.

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  • Joining on NULLs

    - by Dave Ballantyne
    A problem I see on a fairly regular basis is that of dealing with NULL values.  Specifically here, where we are joining two tables on two columns, one of which is ‘optional’ ie is nullable.  So something like this: i.e. Lookup where all the columns are equal, even when NULL.   NULL’s are a tricky thing to initially wrap your mind around.  Statements like “NULL is not equal to NULL and neither is it not not equal to NULL, it’s NULL” can cause a serious brain freeze and leave you a gibbering wreck and needing your mummy. Before we plod on, time to setup some data to demo against. Create table #SourceTable ( Id integer not null, SubId integer null, AnotherCol char(255) not null ) go create unique clustered index idxSourceTable on #SourceTable(id,subID) go with cteNums as ( select top(1000) number from master..spt_values where type ='P' ) insert into #SourceTable select Num1.number,nullif(Num2.number,0),'SomeJunk' from cteNums num1 cross join cteNums num2 go Create table #LookupTable ( Id integer not null, SubID integer null ) go insert into #LookupTable Select top(100) id,subid from #SourceTable where subid is not null order by newid() go insert into #LookupTable Select top(3) id,subid from #SourceTable where subid is null order by newid() If that has run correctly, you will have 1 million rows in #SourceTable and 103 rows in #LookupTable.  We now want to join one to the other. First attempt – Lets just join select * from #SourceTable join #LookupTable on #LookupTable.id = #SourceTable.id and #LookupTable.SubID = #SourceTable.SubID OK, that’s a fail.  We had 100 rows back,  we didn’t correctly account for the 3 rows that have null values.  Remember NULL <> NULL and the join clause specifies SUBID=SUBID, which for those rows is not true. Second attempt – Lets deal with those pesky NULLS select * from #SourceTable join #LookupTable on #LookupTable.id = #SourceTable.id and isnull(#LookupTable.SubID,0) = isnull(#SourceTable.SubID,0) OK, that’s the right result, well done and 99.9% of the time that is where its left. It is a relatively trivial CPU overhead to wrap ISNULL around both columns and compare that result, so no problems.  But, although that’s true, this a relational database we are using here, not a procedural language.  SQL is a declarative language, we are making a request to the engine to get the results we want.  How we ask for them can make a ton of difference. Lets look at the plan for our second attempt, specifically the clustered index seek on the #SourceTable   There are 2 predicates. The ‘seek predicate’ and ‘predicate’.  The ‘seek predicate’ describes how SQLServer has been able to use an Index.  Here, it has been able to navigate the index to resolve where ID=ID.  So far so good, but what about the ‘predicate’ (aka residual probe) ? This is a row-by-row operation.  For each row found in the index matching the Seek Predicate, the leaf level nodes have been scanned and tested using this logical condition.  In this example [Expr1007] is the result of the IsNull operation on #LookupTable and that is tested for equality with the IsNull operation on #SourceTable.  This residual probe is quite a high overhead, if we can express our statement slightly differently to take full advantage of the index and make the test part of the ‘Seek Predicate’. Third attempt – X is null and Y is null So, lets state the query in a slightly manner: select * from #SourceTable join #LookupTable on #LookupTable.id = #SourceTable.id and ( #LookupTable.SubID = #SourceTable.SubID or (#LookupTable.SubID is null and #SourceTable.SubId is null) ) So its slightly wordier and may not be as clear in its intent to the human reader, that is what comments are for, but the key point is that it is now clearer to the query optimizer what our intention is. Let look at the plan for that query, again specifically the index seek operation on #SourceTable No ‘predicate’, just a ‘Seek Predicate’ against the index to resolve both ID and SubID.  A subtle difference that can be easily overlooked.  But has it made a difference to the performance ? Well, yes , a perhaps surprisingly high one. Clever query optimizer well done. If you are using a scalar function on a column, you a pretty much guaranteeing that a residual probe will be used.  By re-wording the query you may well be able to avoid this and use the index completely to resolve lookups. In-terms of performance and scalability your system will be in a much better position if you can.

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  • I love video games and know I want to work in the sector but hate programming

    - by normyp
    I just hate how I'll put in 8-10 hours in and get little to nothing back. The return results for your efforts seem to be pathetically small the majority of the time and I don't find that rewarding enough for me to put in the time and effort to learn programming and make myself better. I've heard game design is fun and I think I'd love that but apparently you can only get into that really if you can program, is that true? I feel a bit lost because I'm doing a degree in Games Technology and am worried that I'm sending myself into a job I'll hate.

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  • how to deal with parallel programming

    - by nkint
    Hi. I know that parallel programming is a big resource in computer graphics, with moder machines, and mayebe a computing model that will be grow up in the near future (is this trend true?). I want to know what is the best way to deal with it. there is some practical general purpose usefulness in studying processor n-dimensional mesh, or bitonic sort in p-ram machines or it's only theory for domain specific hardware used in real particular signal elaborations of scientific simulations? Is this the best way to acquire the know how for how to become acquainted with cuda or opencl? (i'm interested in computer graphics applications) and why functional programming is so important to understand parallel computing? ps: as someone has advice me i have forked this discussion from http://stackoverflow.com/questions/4908677/how-to-deal-with-parallel-programming

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  • What is the ideal laptop for creative coding applications?

    - by Jason
    Hi, I am a creative coder using C++(cinder and OpenFrameworks) I am looking to upgrade from my MacBook, which slowed down to about 3fps this morning. My project involves particles systems and fluids reacting to audio analysis data and computer vision data in real-time. SD or HD? no biggie. I have asked many people what computer I need. Ideally, I want a MacBook Pro. But is that enough power? I've been told that I need a desktop for what I am doing though I'd rather stay portable I've been told that I should go PC linux to get the most power but I'd rather stay mac I've been told that RAM is more of bottleneck than processor speed I've been told that the Graphics Card is more important than CPU and that code optimizations such as using trees over lists, proper threading, sending tasks to the GPU make a bigger difference than the hardware!!! what's true?! what do I need? Any suggestions are greatly appreciated

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  • Checking whether the user input is a str in Python [migrated]

    - by Sahil Babbar
    I checked various questions on Stack Overflow but one thing every logic lacks. Let me demonstrate using Python: while True: user_input = raw_input() if type(user_input) == str: print 'ERROR' else: print 'BINGO' Also, we cannot use input() in place of raw_input() as it gives the error:Traceback (most recent call last): File ".\test.py", line 3, in <module> user_input = int(input()) File "<string>", line 1, in <module> NameError: name 'asdf' is not defined The problem here is that raw_input converts the user input into string so it always prints 'ERROR' and if I change the second line to user_input = int(raw_input) then, it gives an error: Traceback (most recent call last): File ".\test.py", line 3, in <module> user_input = int(raw_input()) ValueError: invalid literal for int() with base 10: 'asdf' I tried this with try and except but it shall work fine to check integer but not a string. I feel that this question may be marked as a duplicate but I think that this query is important, if logically taken.

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