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  • Speed up lighting in deferred shading

    - by kochol
    I implemented a simple deferred shading renderer. I use 3 G-Buffer for storing position (R32F), normal (G16R16F) and albedo (ARGB8). I use sphere map algorithm to store normals in world space. Currently I use inverse of view * projection matrix to calculate the position of each pixel from stored depth value. First I want to avoid per pixel matrix multiplication for calculating the position. Is there another way to store and calculate position in G-Buffer without the need of matrix multiplication Store the normal in view space Every lighting in my engine is in world space and I want do the lighting in view space to speed up my lighting pass. I want an optimized lighting pass for my deferred engine.

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  • how to update a symbolic link target (ln -f -s not working)

    - by solid
    I'm using ln -f -s /var/www/html/releases/build1390 app-current to update symbolic link "app-current" with a new destination. However, this doesn't work, the link "app-current" keeps it original destination, however, I don't get any errors... I'd rather not remove the link and recreate it, just update the target of an existing link. Is that possible?

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  • Hardware instancing for voxel engine

    - by Menno Gouw
    i just did the tutorial on Hardware Instancing from this source: http://www.float4x4.net/index.php/2011/07/hardware-instancing-for-pc-in-xna-4-with-textures/. Somewhere between 900.000 and 1.000.000 draw calls for the cube i get this error "XNA Framework HiDef profile supports a maximum VertexBuffer size of 67108863." while still running smoothly on 900k. That is slightly less then 100x100x100 which are a exactly a million. Now i have seen voxel engines with very "tiny" voxels, you easily get to 1.000.000 cubes in view with rough terrain and a decent far plane. Obviously i can optimize a lot in the geometry buffer method, like rendering only visible faces of a cube or using larger faces covering multiple cubes if the area is flat. But is a vertex buffer of roughly 67mb the max i can work with or can i create multiple?

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  • Speeding up ROW_NUMBER in SQL Server

    - by BlueRaja
    We have a number of machines which record data into a database at sporadic intervals. For each record, I'd like to obtain the time period between this recording and the previous recording. I can do this using ROW_NUMBER as follows: WITH TempTable AS ( SELECT *, ROW_NUMBER() OVER (PARTITION BY Machine_ID ORDER BY Date_Time) AS Ordering FROM dbo.DataTable ) SELECT [Current].*, Previous.Date_Time AS PreviousDateTime FROM TempTable AS [Current] INNER JOIN TempTable AS Previous ON [Current].Machine_ID = Previous.Machine_ID AND Previous.Ordering = [Current].Ordering + 1 The problem is, it goes really slow (several minutes on a table with about 10k entries) - I tried creating separate indicies on Machine_ID and Date_Time, and a single joined-index, but nothing helps. Is there anyway to rewrite this query to go faster?

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  • How exactly does XNA's SpriteBatch work?

    - by David Gouveia
    To be more precise, if I needed to recreate this functionality from scratch in another API (e.g. in OpenGL) what would it need to be capable of doing? I do have a general idea of some of the steps, such as how it prepares an orthographic projection matrix and creates a quad for each draw call. I'm not too familiar, however, with the batching process itself. Are all quads stored in the same vertex buffer? Does it need an index buffer? How are different textures handled? If possible I'd be grateful if you could guide me through the process from when SpriteBatch.Begin() is called until SpriteBatch.End(), at least when using the default Deferred mode.

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  • Correct use of VAO's in OpenGL ES2 for iOS?

    - by sak
    I'm migrating to OpenGL ES2 for one of my iOS projects, and I'm having trouble to get any geometry to render successfully. Here's where I'm setting up the VAO rendering: void bindVAO(int vertexCount, struct Vertex* vertexData, GLushort* indexData, GLuint* vaoId, GLuint* indexId){ //generate the VAO & bind glGenVertexArraysOES(1, vaoId); glBindVertexArrayOES(*vaoId); GLuint positionBufferId; //generate the VBO & bind glGenBuffers(1, &positionBufferId); glBindBuffer(GL_ARRAY_BUFFER, positionBufferId); //populate the buffer data glBufferData(GL_ARRAY_BUFFER, vertexCount, vertexData, GL_STATIC_DRAW); //size of verte position GLsizei posTypeSize = sizeof(kPositionVertexType); glVertexAttribPointer(kVertexPositionAttributeLocation, kVertexSize, kPositionVertexTypeEnum, GL_FALSE, sizeof(struct Vertex), (void*)offsetof(struct Vertex, position)); glEnableVertexAttribArray(kVertexPositionAttributeLocation); //create & bind index information glGenBuffers(1, indexId); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, *indexId); glBufferData(GL_ELEMENT_ARRAY_BUFFER, vertexCount, indexData, GL_STATIC_DRAW); //restore default state glBindVertexArrayOES(0); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0); glBindBuffer(GL_ARRAY_BUFFER, 0); } And here's the rendering step: //bind the frame buffer for drawing glBindFramebuffer(GL_FRAMEBUFFER, outputFrameBuffer); glClear(GL_COLOR_BUFFER_BIT); //use the shader program glUseProgram(program); glClearColor(0.4, 0.5, 0.6, 0.5); float aspect = fabsf(320.0 / 480.0); GLKMatrix4 projectionMatrix = GLKMatrix4MakePerspective(GLKMathDegreesToRadians(65.0f), aspect, 0.1f, 100.0f); GLKMatrix4 modelViewMatrix = GLKMatrix4MakeTranslation(0.0f, 0.0f, -1.0f); GLKMatrix4 mvpMatrix = GLKMatrix4Multiply(projectionMatrix, modelViewMatrix); //glUniformMatrix4fv(projectionMatrixUniformLocation, 1, GL_FALSE, projectionMatrix.m); glUniformMatrix4fv(modelViewMatrixUniformLocation, 1, GL_FALSE, mvpMatrix.m); glBindVertexArrayOES(vaoId); glDrawElements(GL_TRIANGLE_FAN, kVertexCount, GL_FLOAT, &indexId); //bind the color buffer glBindRenderbuffer(GL_RENDERBUFFER, colorRenderBuffer); [context presentRenderbuffer:GL_RENDERBUFFER]; The screen is rendering the color passed to glClearColor correctly, but not the shape passed into bindVAO. Is my VAO being built correctly? Thanks!

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  • CentOS vps is randomly rebooting

    - by develroot
    I have a centos vps (Parallels Virtuozzo container) which has been running for months. However, a few days ago it started to randomly reboot itself, and i can't find out why. And the biggest problem that i don't understand is that it takes 40 minutes to reboot (as far as i can see in the logs) root ~ # cat /var/log/messages | grep shutdown Oct 11 13:52:11 vps27 shutdown[23968]: shutting down for system halt Oct 14 14:55:17 vps27 shutdown[30662]: shutting down for system halt Oct 15 06:21:23 vps27 shutdown[20157]: shutting down for system halt And notice the time difference between shutdown and xinetd's start: Oct 15 06:21:23 vps27 shutdown[20157]: shutting down for system halt Oct 15 06:21:24 vps27 init: Switching to runlevel: 0 Oct 15 06:21:27 vps27 saslauthd[30614]: server_exit : master exited: 30614 Oct 15 06:21:38 vps27 named[30661]: shutting down Oct 15 06:21:47 vps27 exiting on signal 15 Oct 15 07:04:34 vps27 syslogd 1.4.1: restart. Oct 15 07:05:06 vps27 xinetd[1471]: xinetd Version 2.3.14 started with libwrap loadavg labeled-networking options compiled in. Oct 15 07:05:06 vps27 xinetd[1471]: Started working: 0 available services And here's what Parallels Power Panel says in terms of Status Changes: Time Old Status Status Obtained Oct 15, 2011 06:23:46 AM Mounted Down Oct 15, 2011 06:22:31 AM Running Mounted Oct 14, 2011 03:06:48 PM Starting Running Oct 14, 2011 03:06:23 PM Down Starting Oct 14, 2011 03:06:08 PM Mounted Down Oct 14, 2011 02:58:24 PM Running Mounted For some reason it's getting into Mounting mode and then restarts itself. The only problem that i can imagine is disk space utilization, which is now 84%. But can that be a reson for system halt? Time Category Details Type Parameter Oct 15, 2011 07:08:33 AM Resource Resource counter_disk_share_used yellow alert on environment vps27 current value: 82 soft limit: 85 hard limit: 95 Yellow zone counter_disk_share_used Oct 15, 2011 06:27:23 AM Resource Resource counter_disk_share_used yellow alert on environment vps27 current value: 82 soft limit: 85 hard limit: 95 Yellow zone counter_disk_share_used Oct 15, 2011 06:23:50 AM Resource Resource counter_disk_share_used green alert on environment vps27 current value: 0 soft limit: hard limit: 0 Green zone counter_disk_share_used Oct 14, 2011 03:06:24 PM Resource Resource counter_disk_share_used yellow alert on environment vps27 current value: 83 soft limit: 85 hard limit: 95 Yellow zone counter_disk_share_used Oct 14, 2011 03:05:50 PM Resource Resource counter_disk_share_used green alert on environment vps27 current value: 0 soft limit: hard limit: 0 Green zone counter_disk_share_used

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  • Multiple Vertex Buffers per Mesh

    - by Daniel
    I've run into the situation where the size of my mesh with all its vertices and indices, is larger than the (optimal) vertex buffer object upper limit (~8MB). I was wondering if I can sub-divide the mesh across multiple vertex buffers, and somehow retain validity of the indices. Ie a triangle with a indice at the first vertex, and an indice at the last (ie in seperate VBOs). All the while maintaining this within Vertex Array Objects. My thoughts are, save myself the hassle, and for meshes (messes :P) such as this, just use the necessary size ( 8MB); which is what I do at the moment. But ideally my buffer manager (wip) at the moment is using optimal sizes; I may just have to make a special case then... Any ideas? If necessary, a simple C++ code example is appreciated. Note: I have also cross-posted this on stackoverflow, as I was not sure as to which it would be more suitable (its partly a design question).

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  • Why am I getting this error in the logs?

    - by Matt
    Ok so I just started a new ubuntu server 11.10 and i added the vhost and all seems ok ...I also restarted apache but when i visit the browser i get a blank page the server ip is http://23.21.197.126/ but when i tail the log tail -f /var/log/apache2/error.log [Wed Feb 01 02:19:20 2012] [error] [client 208.104.53.51] File does not exist: /etc/apache2/htdocs [Wed Feb 01 02:19:24 2012] [error] [client 208.104.53.51] File does not exist: /etc/apache2/htdocs but my only file in sites-enabled is this <VirtualHost 23.21.197.126:80> ServerAdmin [email protected] ServerName logicxl.com # ServerAlias DocumentRoot /srv/crm/current/public ErrorLog /srv/crm/logs/error.log <Directory "/srv/crm/current/public"> Order allow,deny Allow from all </Directory> </VirtualHost> is there something i am missing .....the document root should be /srv/crm/current/public and not /etc/apache2/htdocs as the error suggests Any ideas on how to fix this UPDATE sudo apache2ctl -S VirtualHost configuration: 23.21.197.126:80 is a NameVirtualHost default server logicxl.com (/etc/apache2/sites-enabled/crm:1) port 80 namevhost logicxl.com (/etc/apache2/sites-enabled/crm:1) Syntax OK UPDATE <VirtualHost *:80> ServerAdmin [email protected] ServerName logicxl.com DocumentRoot /srv/crm/current/public <Directory /> Options FollowSymLinks AllowOverride None </Directory> <Directory /srv/crm/current/public/> Options Indexes FollowSymLinks MultiViews AllowOverride None Order allow,deny allow from all </Directory> ErrorLog ${APACHE_LOG_DIR}/error.log # Possible values include: debug, info, notice, warn, error, crit, # alert, emerg. LogLevel warn CustomLog ${APACHE_LOG_DIR}/access.log combined </VirtualHost>

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  • Hide debug information when running apps from the command line

    - by tutuca
    Most of the time running a gtk application from the command line it starts dumping debug information to the stdio even though I put them in background. Example: ~$ gedit test.html # and ctrl+z to suspend zsh: suspended gedit .zshrc ~$ bg [1] + continued gedit .zshrc ~$ # do some editing (gedit:6208): GtkSourceView-WARNING **: Could not find word to remove in buffer (whoosh), this should not happen! (gedit:6208): GtkSourceView-WARNING **: Could not find word to remove in buffer (haystack), this should not happen! I want to note that the error, or warning, changes according to what I'm doing at the moment. The GtkSourceView-WARNING shown here is one of the cases. Anyway... Do you know if it's at all possible to avoid getting that information printed out?

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  • How do I implement SkyBox in xna 4.0 Reach Profile (for Windows Phone 7)?

    - by Biny
    I'm trying to Implement SkyBox in my phone game. Most of the samples in the web are for HiDef profile, and they are using custom effects (that not supported on Windows Phone). I've tried to follow this guide. But for some reason my SkyBox is not rendered. This is my SkyBox class: using System; using System.Collections.Generic; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Graphics; using Rocuna.Core; using Rocuna.GameEngine.Graphics; using Rocuna.GameEngine.Graphics.Components; namespace Rocuna.GameEngine.Extension.WP7.Graphics { /// <summary> /// Sky box element for phone games. /// </summary> public class SkyBox : SkyBoxBase { /// <summary> /// Initializes a new instance of the <see cref="SkyBoxBase"/> class. /// </summary> /// <param name="game">The Game that the game component should be attached to.</param> public SkyBox(TextureCube cube, Game game) : base(game) { Cube = cube; CubeFaces = new Texture2D[6]; PositionOffset = new Vector3(20, 20, 20); CreateGraphic(512); StripTexturesFromCube(); InitializeData(Game.GraphicsDevice); } #region Properties /// <summary> /// Gets or sets the position offset. /// </summary> /// <value> /// The position offset. /// </value> public Vector3 PositionOffset { get; set; } /// <summary> /// Gets or sets the position. /// </summary> /// <value> /// The position. /// </value> public Vector3 Position { get; set; } /// <summary> /// Gets or sets the cube. /// </summary> /// <value> /// The cube. /// </value> public TextureCube Cube { get; set; } /// <summary> /// Gets or sets the pixel array. /// </summary> /// <value> /// The pixel array. /// </value> public Color[] PixelArray { get; set; } /// <summary> /// Gets or sets the cube faces. /// </summary> /// <value> /// The cube faces. /// </value> public Texture2D[] CubeFaces { get; set; } /// <summary> /// Gets or sets the vertex buffer. /// </summary> /// <value> /// The vertex buffer. /// </value> public VertexBuffer VertexBuffer { get; set; } /// <summary> /// Gets or sets the index buffer. /// </summary> /// <value> /// The index buffer. /// </value> public IndexBuffer IndexBuffer { get; set; } /// <summary> /// Gets or sets the effect. /// </summary> /// <value> /// The effect. /// </value> public BasicEffect Effect { get; set; } #endregion protected override void LoadContent() { } public override void Update(GameTime gameTime) { var camera = Game.GetService<GraphicManager>().CurrentCamera; this.Position = camera.Position + PositionOffset; base.Update(gameTime); } public override void Draw(GameTime gameTime) { DrawOrder = int.MaxValue; var graphics = Effect.GraphicsDevice; graphics.DepthStencilState = new DepthStencilState() { DepthBufferEnable = false }; graphics.RasterizerState = new RasterizerState() { CullMode = CullMode.None }; graphics.BlendState = new BlendState(); graphics.SamplerStates[0] = SamplerState.AnisotropicClamp; graphics.SetVertexBuffer(VertexBuffer); graphics.Indices = IndexBuffer; Effect.Texture = CubeFaces[0]; Effect.CurrentTechnique.Passes[0].Apply(); graphics.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, _vertices.Count, 0, 2); Effect.Texture = CubeFaces[1]; Effect.CurrentTechnique.Passes[0].Apply(); graphics.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, _vertices.Count, 6, 2); Effect.Texture = CubeFaces[2]; Effect.CurrentTechnique.Passes[0].Apply(); graphics.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, _vertices.Count, 12, 2); Effect.Texture = CubeFaces[3]; Effect.CurrentTechnique.Passes[0].Apply(); graphics.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, _vertices.Count, 18, 2); Effect.Texture = CubeFaces[4]; Effect.CurrentTechnique.Passes[0].Apply(); graphics.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, _vertices.Count, 24, 2); Effect.Texture = CubeFaces[5]; Effect.CurrentTechnique.Passes[0].Apply(); graphics.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, _vertices.Count, 30, 2); base.Draw(gameTime); } #region Fields private List<VertexPositionNormalTexture> _vertices = new List<VertexPositionNormalTexture>(); private List<ushort> _indices = new List<ushort>(); #endregion #region Private methods private void InitializeData(GraphicsDevice graphicsDevice) { VertexBuffer = new VertexBuffer(graphicsDevice, typeof(VertexPositionNormalTexture), _vertices.Count, BufferUsage.None); VertexBuffer.SetData<VertexPositionNormalTexture>(_vertices.ToArray()); // Create an index buffer, and copy our index data into it. IndexBuffer = new IndexBuffer(graphicsDevice, typeof(ushort), _indices.Count, BufferUsage.None); IndexBuffer.SetData<ushort>(_indices.ToArray()); // Create a BasicEffect, which will be used to render the primitive. Effect = new BasicEffect(graphicsDevice); Effect.TextureEnabled = true; Effect.EnableDefaultLighting(); } private void CreateGraphic(float size) { Vector3[] normals = { Vector3.Right, Vector3.Left, Vector3.Up, Vector3.Down, Vector3.Backward, Vector3.Forward, }; Vector2[] textureCoordinates = { Vector2.One, Vector2.UnitY, Vector2.Zero, Vector2.UnitX, Vector2.Zero, Vector2.UnitX, Vector2.One, Vector2.UnitY, Vector2.Zero, Vector2.UnitX, Vector2.One, Vector2.UnitY, Vector2.Zero, Vector2.UnitX, Vector2.One, Vector2.UnitY, Vector2.UnitY, Vector2.Zero, Vector2.UnitX, Vector2.One, Vector2.UnitY, Vector2.Zero, Vector2.UnitX, Vector2.One, }; var index = 0; foreach (var normal in normals) { var side1 = new Vector3(normal.Z, normal.X, normal.Y); var side2 = Vector3.Cross(normal, side1); AddIndex(CurrentVertex + 0); AddIndex(CurrentVertex + 1); AddIndex(CurrentVertex + 2); AddIndex(CurrentVertex + 0); AddIndex(CurrentVertex + 2); AddIndex(CurrentVertex + 3); AddVertex((normal - side1 - side2) * size / 2, normal, textureCoordinates[index++]); AddVertex((normal - side1 + side2) * size / 2, normal, textureCoordinates[index++]); AddVertex((normal + side1 + side2) * size / 2, normal, textureCoordinates[index++]); AddVertex((normal + side1 - side2) * size / 2, normal, textureCoordinates[index++]); } } protected void StripTexturesFromCube() { PixelArray = new Color[Cube.Size * Cube.Size]; for (int s = 0; s < CubeFaces.Length; s++) { CubeFaces[s] = new Texture2D(Game.GraphicsDevice, Cube.Size, Cube.Size, false, SurfaceFormat.Color); switch (s) { case 0: Cube.GetData<Color>(CubeMapFace.PositiveX, PixelArray); CubeFaces[s].SetData<Color>(PixelArray); break; case 1: Cube.GetData(CubeMapFace.NegativeX, PixelArray); CubeFaces[s].SetData(PixelArray); break; case 2: Cube.GetData(CubeMapFace.PositiveY, PixelArray); CubeFaces[s].SetData(PixelArray); break; case 3: Cube.GetData(CubeMapFace.NegativeY, PixelArray); CubeFaces[s].SetData(PixelArray); break; case 4: Cube.GetData(CubeMapFace.PositiveZ, PixelArray); CubeFaces[s].SetData(PixelArray); break; case 5: Cube.GetData(CubeMapFace.NegativeZ, PixelArray); CubeFaces[s].SetData(PixelArray); break; } } } protected void AddVertex(Vector3 position, Vector3 normal, Vector2 textureCoordinates) { _vertices.Add(new VertexPositionNormalTexture(position, normal, textureCoordinates)); } protected void AddIndex(int index) { if (index > ushort.MaxValue) throw new ArgumentOutOfRangeException("index"); _indices.Add((ushort)index); } protected int CurrentVertex { get { return _vertices.Count; } } #endregion } }

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  • rkhunter warns of inode change by no file modification date changes

    - by Nicholas Tolley Cottrell
    I have several systems running Centos 6 with rkhunter installed. I have a daily cron running rkhunter and reporting back via email. I very often get reports like: ---------------------- Start Rootkit Hunter Scan ---------------------- Warning: The file properties have changed: File: /sbin/fsck Current inode: 6029384 Stored inode: 6029326 Warning: The file properties have changed: File: /sbin/ip Current inode: 6029506 Stored inode: 6029343 Warning: The file properties have changed: File: /sbin/nologin Current inode: 6029443 Stored inode: 6029531 Warning: The file properties have changed: File: /bin/dmesg Current inode: 13369362 Stored inode: 13369366 From what I understand, rkhunter will usually report a changed hash and/or modification date on the scanned files to, so this leads me to think that there is no real change. My question: is there some other activity on the machine that could make the inode change (running ext4) or is this really yum making regular (~ once a week) changes to these files as part of normal security updates?

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  • Can I animate render targets or the swap chain?

    - by Eric F.
    I want to animate some synthetic video bits to fullscreen w/o tearing. Can I set up D3D 9/10/11 in exclusive mode, and have it present a series of buffers that I'm writing to? I know how to copy system memory bits into a texture, then draw that texture as a fullscreen quad, but it seems like overkill. Why should I use the triangle rasterizer when I want to do something so simple? All I want to do is set up a long (4-8 buffer) swapchain and set the bits of the back buffer that is about to be displayed. Or, I want to allocate 4-8 RenderTargets, and on each frame, copy the bits from system memory to the RenderTarget, then set it as the next thing to display. I've never seen or heard about anybody doing this, but it seems so dead simple!

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  • Is it normal for an AC adapter to drop voltage if it's not used by a laptop?

    - by leladax
    I'm currently investigating the livelihood of a laptop adaptor and I noticed, unlike another adaptor it drops voltage to almost zero after I also attempt to measure its current [while it did show voltage at first, before measuring current]. The other adaptor normally shows voltage and then normally shows some current and then if it turns to measure voltage, it shows it normally again. I assume the adaptor is faulty, however, I want to make sure if laptop adaptors turn off themselves if they aren't used normally by a laptop.

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  • What is the situation about OpenGL under Ubuntu Unity and Gnome3?

    - by user827992
    In a GNU/linux distribution is usually installed Xorg as main graphical server, it operates with a client-server logic, a special windows is designate as desktop environment and this special windows can handle all the eyecandy stuff like decorations, icons and effects. The problem is that the latest UI heavily relies on hardware acceleration, Unity is an overlay on Compiz and the Gnome-shell also require an active driver for the GPU to work well: the problem is: on the same OS I can find multiple implementations of OpenGL who is handling my OpenGL buffer? how the OpenGL buffer is managed compared to the other windows? how can I be sure that my OpenGL implementation is glued to the hardware and is not related to the client-server logic of Xorg? For example I have tried the clutter library and I have only experienced problems under both Unity and GTK/Gnome, no problem under other OS.

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  • What are best practices for testing programs with stochastic behavior?

    - by John Doucette
    Doing R&D work, I often find myself writing programs that have some large degree of randomness in their behavior. For example, when I work in Genetic Programming, I often write programs that generate and execute arbitrary random source code. A problem with testing such code is that bugs are often intermittent and can be very hard to reproduce. This goes beyond just setting a random seed to the same value and starting execution over. For instance, code might read a message from the kernal ring buffer, and then make conditional jumps on the message contents. Naturally, the ring buffer's state will have changed when one later attempts to reproduce the issue. Even though this behavior is a feature it can trigger other code in unexpected ways, and thus often reveals bugs that unit tests (or human testers) don't find. Are there established best practices for testing systems of this sort? If so, some references would be very helpful. If not, any other suggestions are welcome!

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  • Graph data structures and journal format for mini-IDE

    - by matec
    Background: I am writing a small/partial IDE. Code is internally converted/parsed into a graph data structure (for fast navigation, syntax-check etc). Functionality to undo/redo (also between sessions) and restoring from crash is implemented by writing to and reading from journal. The journal records modifications to the graph (not to the source). Question: I am hoping for advice on a decision on data-structures and journal format. For the graph I see two possible versions: g-a Graph edges are implemented in the way that one node stores references to other nodes via memory address g-b Every node has an ID. There is an ID-to-memory-address map. Graph uses IDs (instead of addresses) to connect nodes. Moving along an edge from one node to another each time requires lookup in ID-to-address map. And also for the journal: j-a There is a current node (like current working directory in a shell + file-system setting). The journal contains entries like "create new node and connect to current", "connect first child of current node" (relative IDs) j-b Journal uses absolute IDs, e.g. "delete edge 7 - 5", "delete node 5" I could e.g. combine g-a with j-a or combine g-b with j-b. In principle also g-b and j-a should be possible. [My first/original attempt was g-a and a version of j-b that uses addresses, but that turned out to cause severe restrictions: nodes cannot change their addresses (or journal would have to keep track of it), and using journal between two sessions is a mess (or even impossible)] I wonder if variant a or variant b or a combination would be a good idea, what advantages and disadvantages they would have and especially if some variant might be causing troubles later.

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  • How can I convert an image from raw data in Android without any munging?

    - by stephelton
    I have raw image data (may be .png, .jpg, ...) and I want it converted in Android without changing its pixel depth (bpp). In particular, when I load a grayscale (8 bpp) image that I want to use as alpha (glTexImage() with GL_ALPHA), it converts it to 16 bpp (presumably 5_6_5). While I do have a plan B (actually, I'm probably on plan 'E' by now, this is really becoming annoying) I would really like to discover an easy way to do this using what is readily available in the API. So far, I'm using BitmapFactory.decodeByteArray(). While I'm at it. I'm doing this from a native environment via JNI (passing the buffer in from C, and a new buffer back to C from Java). Any portable solution in C/C++ would be preferable, but I don't want to introduce anything that might break in future versions of Android, etc.

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  • Deferred contexts and inheriting state from the immediate context

    - by dreijer
    I took my first stab at using deferred contexts in DirectX 11 today. Basically, I created my deferred context using CreateDeferredContext() and then drew a simple triangle strip with it. Early on in my test application, I call OMSetRenderTargets() on the immediate context in order to render to the swap chain's back buffer. Now, after having read the documentation on MSDN about deferred contexts, I assumed that calling ExecuteCommandList() on the immediate context would execute all of the deferred commands as "an extension" to the commands that had already been executed on the immediate context, i.e. the triangle strip I rendered in the deferred context would be rendered to the swap chain's back buffer. That didn't seem to be the case, however. Instead, I had to manually pull out the immediate context's render target (using OMGetRenderTargets()) and then set it on the deferred context with OMSetRenderTargets(). Am I doing something wrong or is that the way deferred contexts work?

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  • Condensing/abstracting the path shown on each line in PowerShell

    - by kRON
    I've started using virtualenv for my Python projects. Since the working directory for my projects is now deeply nested, the path has started to take up half of my screen! Is it possible to somehow have PowerShell condense the path to the current working directory, from something like C:\Users\kRON\Desktop\Current work\Python\dsp\src to C:\Users\kRON\Deskto~1\Curren~2\Python\dsp\src or, better yet, to match C:\Users\kRON\Desktop\Current work\Python\and just replace it with ~python\?

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  • Implementing invisible bones

    - by DeadMG
    I suddenly have the feeling that I have absolutely no idea how to implement invisible objects/bones. Right now, I use hardware instancing to store the world matrix of every bone in a vertex buffer, and then send them all to the pipeline. But when dealing with frustrum culling, or having them set to invisible by my simulation for other reasons, means that some of them will be randomly invisible. Does this mean I effectively need to re-fill the buffer from scratch every frame with only the visible unit's matrices? This seems to me like it would involve a lot of wasted bandwidth.

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  • How do i use latest Pulseaudio in 11.10?

    - by YumYumYum
    Ubuntu 11.04 i had pulseaudio from source compiled and i used it to learn, it always worked (git versions). But since i have Ubuntu 11.10, i can install it but i can not use it anymore like i do in 11.04 before. Everytime i play something its throwing this: $ speaker-test speaker-test 1.0.24.2 Playback device is default Stream parameters are 48000Hz, S16_LE, 1 channels Using 16 octaves of pink noise Rate set to 48000Hz (requested 48000Hz) Buffer size range from 192 to 2097152 Period size range from 64 to 699051 Using max buffer size 2097152 Periods = 4 ALSA lib pcm_pulse.c:746:(pulse_prepare) PulseAudio: Unable to create stream: Invalid argument Unable to set hw params for playback: Input/output error Setting of hwparams failed: Input/output error How to make pulseaudio work in 11.10 from source?

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  • Processing Kinect v2 Color Streams in Parallel

    - by Chris Gardner
    Originally posted on: http://geekswithblogs.net/freestylecoding/archive/2014/08/20/processing-kinect-v2-color-streams-in-parallel.aspxProcessing Kinect v2 Color Streams in Parallel I've really been enjoying being a part of the Kinect for Windows Developer's Preview. The new hardware has some really impressive capabilities. However, with great power comes great system specs. Unfortunately, my little laptop that could is not 100% up to the task; I've had to get a little creative. The most disappointing thing I've run into is that I can't always cleanly display the color camera stream in managed code. I managed to strip the code down to what I believe is the bear minimum: using( ColorFrame _ColorFrame = e.FrameReference.AcquireFrame() ) { if( null == _ColorFrame ) return;   BitmapToDisplay.Lock(); _ColorFrame.CopyConvertedFrameDataToIntPtr( BitmapToDisplay.BackBuffer, Convert.ToUInt32( BitmapToDisplay.BackBufferStride * BitmapToDisplay.PixelHeight ), ColorImageFormat.Bgra ); BitmapToDisplay.AddDirtyRect( new Int32Rect( 0, 0, _ColorFrame.FrameDescription.Width, _ColorFrame.FrameDescription.Height ) ); BitmapToDisplay.Unlock(); } With this snippet, I'm placing the converted Bgra32 color stream directly on the BackBuffer of the WriteableBitmap. This gives me pretty smooth playback, but I still get the occasional freeze for half a second. After a bit of profiling, I discovered there were a few problems. The first problem is the size of the buffer along with the conversion on the buffer. At this time, the raw image format of the data from the Kinect is Yuy2. This is great for direct video processing. It would be ideal if I had a WriteableVideo object in WPF. However, this is not the case. Further digging led me to the real problem. It appears that the SDK is converting the input serially. Let's think about this for a second. The color camera is a 1080p camera. As we should all know, this give us a native resolution of 1920 x 1080. This produces 2,073,600 pixels. Yuy2 uses 4 bytes per 2 pixel, for a buffer size of 4,147,200 bytes. Bgra32 uses 4 bytes per pixel, for a buffer size of 8,294,400 bytes. The SDK appears to be doing this on one thread. I started wondering if I chould do this better myself. I mean, I have 8 cores in my system. Why can't I use them all? The first problem is converting a Yuy2 frame into a Bgra32 frame. It is NOT trivial. I spent a day of research of just how to do this. In the end, I didn't even produce the best algorithm possible, but it did work. After I managed to get that to work, I knew my next step was the get the conversion operation off the UI Thread. This was a simple process of throwing the work into a Task. Of course, this meant I had to marshal the final write to the WriteableBitmap back to the UI thread. Finally, I needed to vectorize the operation so I could run it safely in parallel. This was, mercifully, not quite as hard as I thought it would be. I had my loop return an index to a pair of pixels. From there, I had to tell the loop to do everything for this pair of pixels. If you're wondering why I did it for pairs of pixels, look back above at the specification for the Yuy2 format. I won't go into full detail on why each 4 bytes contains 2 pixels of information, but rest assured that there is a reason why the format is described in that way. The first working attempt at this algorithm successfully turned my poor laptop into a space heater. I very quickly brought and maintained all 8 cores up to about 97% usage. That's when I remembered that obscure option in the Task Parallel Library where you could limit the amount of parallelism used. After a little trial and error, I discovered 4 parallel tasks was enough for most cases. This yielded the follow code: private byte ClipToByte( int p_ValueToClip ) { return Convert.ToByte( ( p_ValueToClip < byte.MinValue ) ? byte.MinValue : ( ( p_ValueToClip > byte.MaxValue ) ? byte.MaxValue : p_ValueToClip ) ); }   private void ColorFrameArrived( object sender, ColorFrameArrivedEventArgs e ) { if( null == e.FrameReference ) return;   // If you do not dispose of the frame, you never get another one... using( ColorFrame _ColorFrame = e.FrameReference.AcquireFrame() ) { if( null == _ColorFrame ) return;   byte[] _InputImage = new byte[_ColorFrame.FrameDescription.LengthInPixels * _ColorFrame.FrameDescription.BytesPerPixel]; byte[] _OutputImage = new byte[BitmapToDisplay.BackBufferStride * BitmapToDisplay.PixelHeight]; _ColorFrame.CopyRawFrameDataToArray( _InputImage );   Task.Factory.StartNew( () => { ParallelOptions _ParallelOptions = new ParallelOptions(); _ParallelOptions.MaxDegreeOfParallelism = 4;   Parallel.For( 0, Sensor.ColorFrameSource.FrameDescription.LengthInPixels / 2, _ParallelOptions, ( _Index ) => { // See http://msdn.microsoft.com/en-us/library/windows/desktop/dd206750(v=vs.85).aspx int _Y0 = _InputImage[( _Index << 2 ) + 0] - 16; int _U = _InputImage[( _Index << 2 ) + 1] - 128; int _Y1 = _InputImage[( _Index << 2 ) + 2] - 16; int _V = _InputImage[( _Index << 2 ) + 3] - 128;   byte _R = ClipToByte( ( 298 * _Y0 + 409 * _V + 128 ) >> 8 ); byte _G = ClipToByte( ( 298 * _Y0 - 100 * _U - 208 * _V + 128 ) >> 8 ); byte _B = ClipToByte( ( 298 * _Y0 + 516 * _U + 128 ) >> 8 );   _OutputImage[( _Index << 3 ) + 0] = _B; _OutputImage[( _Index << 3 ) + 1] = _G; _OutputImage[( _Index << 3 ) + 2] = _R; _OutputImage[( _Index << 3 ) + 3] = 0xFF; // A   _R = ClipToByte( ( 298 * _Y1 + 409 * _V + 128 ) >> 8 ); _G = ClipToByte( ( 298 * _Y1 - 100 * _U - 208 * _V + 128 ) >> 8 ); _B = ClipToByte( ( 298 * _Y1 + 516 * _U + 128 ) >> 8 );   _OutputImage[( _Index << 3 ) + 4] = _B; _OutputImage[( _Index << 3 ) + 5] = _G; _OutputImage[( _Index << 3 ) + 6] = _R; _OutputImage[( _Index << 3 ) + 7] = 0xFF; } );   Application.Current.Dispatcher.Invoke( () => { BitmapToDisplay.WritePixels( new Int32Rect( 0, 0, Sensor.ColorFrameSource.FrameDescription.Width, Sensor.ColorFrameSource.FrameDescription.Height ), _OutputImage, BitmapToDisplay.BackBufferStride, 0 ); } ); } ); } } This seemed to yield a results I wanted, but there was still the occasional stutter. This lead to what I realized was the second problem. There is a race condition between the UI Thread and me locking the WriteableBitmap so I can write the next frame. Again, I'm writing approximately 8MB to the back buffer. Then, I started thinking I could cheat. The Kinect is running at 30 frames per second. The WPF UI Thread runs at 60 frames per second. This made me not feel bad about exploiting the Composition Thread. I moved the bulk of the code from the FrameArrived handler into CompositionTarget.Rendering. Once I was in there, I polled from a frame, and rendered it if it existed. Since, in theory, I'm only killing the Composition Thread every other hit, I decided I was ok with this for cases where silky smooth video performance REALLY mattered. This ode looked like this: private byte ClipToByte( int p_ValueToClip ) { return Convert.ToByte( ( p_ValueToClip < byte.MinValue ) ? byte.MinValue : ( ( p_ValueToClip > byte.MaxValue ) ? byte.MaxValue : p_ValueToClip ) ); }   void CompositionTarget_Rendering( object sender, EventArgs e ) { using( ColorFrame _ColorFrame = FrameReader.AcquireLatestFrame() ) { if( null == _ColorFrame ) return;   byte[] _InputImage = new byte[_ColorFrame.FrameDescription.LengthInPixels * _ColorFrame.FrameDescription.BytesPerPixel]; byte[] _OutputImage = new byte[BitmapToDisplay.BackBufferStride * BitmapToDisplay.PixelHeight]; _ColorFrame.CopyRawFrameDataToArray( _InputImage );   ParallelOptions _ParallelOptions = new ParallelOptions(); _ParallelOptions.MaxDegreeOfParallelism = 4;   Parallel.For( 0, Sensor.ColorFrameSource.FrameDescription.LengthInPixels / 2, _ParallelOptions, ( _Index ) => { // See http://msdn.microsoft.com/en-us/library/windows/desktop/dd206750(v=vs.85).aspx int _Y0 = _InputImage[( _Index << 2 ) + 0] - 16; int _U = _InputImage[( _Index << 2 ) + 1] - 128; int _Y1 = _InputImage[( _Index << 2 ) + 2] - 16; int _V = _InputImage[( _Index << 2 ) + 3] - 128;   byte _R = ClipToByte( ( 298 * _Y0 + 409 * _V + 128 ) >> 8 ); byte _G = ClipToByte( ( 298 * _Y0 - 100 * _U - 208 * _V + 128 ) >> 8 ); byte _B = ClipToByte( ( 298 * _Y0 + 516 * _U + 128 ) >> 8 );   _OutputImage[( _Index << 3 ) + 0] = _B; _OutputImage[( _Index << 3 ) + 1] = _G; _OutputImage[( _Index << 3 ) + 2] = _R; _OutputImage[( _Index << 3 ) + 3] = 0xFF; // A   _R = ClipToByte( ( 298 * _Y1 + 409 * _V + 128 ) >> 8 ); _G = ClipToByte( ( 298 * _Y1 - 100 * _U - 208 * _V + 128 ) >> 8 ); _B = ClipToByte( ( 298 * _Y1 + 516 * _U + 128 ) >> 8 );   _OutputImage[( _Index << 3 ) + 4] = _B; _OutputImage[( _Index << 3 ) + 5] = _G; _OutputImage[( _Index << 3 ) + 6] = _R; _OutputImage[( _Index << 3 ) + 7] = 0xFF; } );   BitmapToDisplay.WritePixels( new Int32Rect( 0, 0, Sensor.ColorFrameSource.FrameDescription.Width, Sensor.ColorFrameSource.FrameDescription.Height ), _OutputImage, BitmapToDisplay.BackBufferStride, 0 ); } }

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  • Simple electric DC question. Currency consumption

    - by Bobb
    Suppose you have DC power supply and a consumer connected to it (i.e. computer PSU and a hard drive). Suppose PSU which was supplied with the consumer has output 5V 1A. So I assume that the consumer should not consume more than 1A. Suppose the original PSU is broken now and I want to replace it with the one I have which is 5V 10A. My guess is that current is something which depends on the consumer. So if the consumer consumes normally 1A then it will not consume more than that even if it is connected to 10A PSU. In other word - am I right assuming that the consumer will not burn out being connected to a power supply with higher current output? P.S. my understanding is that voltage is something independent from the consumer. If you give it higher voltage it will burn (voltage is from PSU to the consumer). However current must be in opposite - consumer sucks as much current as it need not as much as PSU can provide (of course given that max PSU current is greater than the consumer needs)

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  • View space lighting in deferred shading

    - by kochol
    I implemented a simple deferred shading renderer. I use 3 G-Buffer for storing position (R32F), normal (G16R16F) and albedo (ARGB8). I use sphere map algorithm to store normals in world space. Currently I use inverse of view * projection matrix to calculate the position of each pixel from stored depth value. First I want to avoid per pixel matrix multiplication for calculating the position. Is there another way to store and calculate position in G-Buffer without the need of matrix multiplication Store the normal in view space Every lighting in my engine is in world space and I want do the lighting in view space to speed up my lighting pass. I want an optimized lighting pass for my deferred engine.

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