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• Determining cause of random latency/loading issues

  - by Sherwin Flight

  I'm not sure exactly what details to post in regards to my issue, because I'm not sure what is relevant. Prior to the end of September my websites all loaded quickly, in almost all cases. Loading time wasn't usually more than a few seconds. However, since the end of September I noticed a big increase in page loading times. In some cases pages were taking 30 seconds or more to load. I do have a remote monitoring service monitoring some of the sites as well, and the image below shows the response times over the past month. The response times shown at the beginning of this graph were what the usual response times were prior to this issue occurring. You can see that there has been a significant increase in response times from the beginning to the end of this graph. The thing is, the problem is not happening 100% of the time. If I click through the site, or even just keep refreshing the page, about 25% of the time the pages load quickly, the remaining 75% of the time they load slowly. Sometimes the pages take so long to load that they time out, and don't load at all. I have contacted my hosting provider, and they said things at their end was fine. I don't believe the problem is my home internet provider, because all other websites load without a problem. The server is located in Texas, USA. This also raises another interesting point. My remote monitor checks my site from two locations, California, USA, and London, England. As you can see in the chart below the response time is actually shorter when checked from London, which doesn't seem to make sense, since the server is physically closer to the California monitoring location. I would have expected the London monitoring location to have higher response times since they are physically farther away. I should also point out that in some traceroute test I've done it seem like the first connection to the server seems to take the longest, then after that the rest of the page loads quickly. Below is a little chart showing the times for the first connection to the server. So, what could be causing this problem, and what steps can I take to resolve it or at least narrow down the problem? Sending the request to the server was very quick, and receiving the reply back seems pretty quick, but the WAIT time is really long. So it connects, sends the request, but then waits close to 30 seconds before it starts receiving data back. I am also aware that there are things I can do to speed up page loading times, like reducing the number of css/js files used on a page, compressing images, etc. This is not really what the source of the problem is though, because nothing has really changed on the site since before the problem started, and other sites on the same server are loading slowly as well. Any help or advice is much appreciated.

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• Creating a Reporting Services Histogram Chart for Statistical Distribution Analysis

  Typically transactional data is quite detailed and analyzing an entire dataset on a graph is not feasible. Generally such data is analyzed using some form of aggregation or frequency distribution. One of the specialized charts generally used in Reporting Services for statistical distribution is Histogram Charts. In this tip we look at how Histogram Charts can be used for statistical distribution analysis and how to create and configure this type of chart in SSRS.

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• How can I tweak this A* search pathfinding algorithm to handle different terrain movement values?

  - by user422318

  I'm creating a 2D map-based action game with similar interaction design as Diablo II. In other words, the player clicks around a map to move their player. I just finished player movement and am moving on to pathfinding. In the game, enemies should charge the player's character. There are also five different terrain types that give different movement bonuses. I want the AI to take advantage of these terrain bonuses as they try to reach the player. I was told to check out the A* search algorithm (http://en.wikipedia.org/wiki/A*_search_algorithm). I'm doing this game in HTML5 and JavaScript, and found a version in JavaScript: http://www.briangrinstead.com/blog/astar-search-algorithm-in-javascript I'm trying to figure out how to tweak it though. Below are my ideas about what I need to change. What else do I need to worry about? When I create a graph, I will need to initialize the 2D array I pass in passed on with a traversal of a map that corresponds to the different terrain types. in graph.js: "GraphNodeType" definition needs to be modified to handle the 5 terrain types. There will be no walls. in astar.js: The g and h scoring will need to be modified. How should I do this? in astar.js: isWall() should probably be removed. My game doesn't have walls. in astar.js: I'm not sure what this is. I think it indicates a node that isn't valid to be processed. When would this happen, though? At a high level, how do I change this algorithm from "oh, is there a wall there?" to "will this terrain get me to the player faster than the terrain around me?" Because of time, I'm also debating reusing my Bresenham algorithm for the enemies. Unfortunately, the different terrain movement bonuses won't be used by the AI, which will make the game suck. :/ I'd really like to have this in for the prototype, but I'm not a developer by trade nor am I a computer scientist. :D If you know of any code that does what I'm looking for, please share! Sanity check tips for this are also appreciated.

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• State Transition Constraints

  Data Validation in a database is a lot more complex than seeing if a string parameter really is an integer. A commercial world is full of complex rules for sequences of procedures, of fixed or variable lifespans, Warranties, commercial offers and bids. All this requires considerable subtlety to prevent bad data getting in, and if it does, locating and fixing the problem. Joe Celko shows how useful a State transition graph can be, and how essential it can become with the time aspect added.

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• C Programming arrays, I dont understand how I would go about making this program, If anyone can just guide me through the basic outline please :) [on hold]

  - by Rashmi Kohli

  Problem The temperature of a car engine has been measured, from real-world experiments, as shown in the table and graph below: Time (min) Temperature (oC) 0 20 1 36 2 61 3 68 4 77 5 110 Use linear regression to find the engine’s temperature at 1.5 minutes, 4.3 minutes, and any other time specified by the user. Background In engineering, many times we measure several data points in an experiment, but then we need to predict a value that we have not measured which lies between two measured values, such as the problem statement above. If the relation between the measured parameters seems to be roughly linear, then we can use linear regression to find the relationship between those parameters. In the graph of the problem statement above, the relation seems to be roughly linear. Hence, we can apply linear regression to the above problem. Assuming y {y0, y1, …yn-1} has a linear relation with x {x0, x1, … xn-1}, we can say that: y = mx+b where m and b can be found with linear regression as follows: For the problem in this lab, using linear regression gives us the following line (in blue) compared to the measured curve (in red). As you can see, there is usually a difference between the measured values and the estimated (predicted) values. What linear regression does is to minimize those differences and still give us a straight line (blue). Other methods, such as non-linear regression, are also possible to achieve higher accuracy and better curve fitting. Requirements Your program should first print the table of the temperatures similar to the way it’s printed in the problem statement. It should then calculate the temperature at minute 1.5 and 4.3 and show the answers to the user. Next, it should prompt the user to enter a time in minutes (or -1 to quit), and after reading the user’s specified time it should give the value of the engine’s temperature at that time. It should then go back to the prompt. Hints •Use a one dimensional array to store the temperature values given in the problem statement. •Use functions to separate tasks such as calculating m, calculating b, calculating the temperature at a given time, printing the prompt, etc. You can then give your algorithm as well as you pseudo code per function, as opposed to one large algorithm diagram or one large sequence of pseudo code.

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• HRESULT E_FAIL Exception! (5 replies)

  Hi, I am trying to generate a powerpoint presentation in C#. It works well on my local machine which is running XP. When I run the application on Windows Server 2003 (our Server) the presentation gives HRESULT E FAIL when I call the following code chart (Microsoft.Office.Interop.Graph.Chart)slide.Shapes.AddOLEObject (GetLeft(i), GetTop(i), GetWidth(i), GetHeight(i), &quot;MSGraph.Chart&quot;, &quot;&quot;, Microsoft....

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• Not able to get graphs on screen with gnuplot

  - by user81194

  I have installed 12.04 along with Windows 7 and also installed gnuplot 4.6.0. When I type gnuplot on the terminal, I am getting the error message: Terminal type set to unknown. When I tried plot sin(x), the graph does not appear on the screen. However, I am able to make a postscript file. I tried set terminal 'x11', system responds with: unknown or ambiguous terminal. Please help me solve this problem.

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• The SQL of Membership: Equivalence Classes & Cliques

  It is awkward to do 'Graph databases' in SQL to explore the sort of relationships and memberships in social networks because equivalence relations are classes (a set of sets) rather than sets. However one can explore graphs in SQL if the relationship has all three of the mathematical properties needed for an equivalence relationship. FREE eBook – "45 Database Performance Tips for Developers"Improve your database performance with 45 tips from SQL Server MVPs and industry experts. Get the eBook here.

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• See number of SVN Checkins per folder

  - by Farseeker

  I have a very large SVN repository (working copy of several gb) that has just reached its 20,000th checkin. As a bit of an interesting statistic for our team (and to partly celebrate our 20,000th checkin) I'd like to make a graph showing which folders in the repository have had the most checkins. Is there any way to do this? We mostly use integrated SVN clients in our IDE and Tortoise SVN, but I'm willing to get other tools for this one-off thing.

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• How to get "Friends who like/play games" list (similar to Farmville 2)

  - by FBAppDev

  I'm working on a Facebook app, and I'm trying to get a friends list similar to Farmville 2. They have a "friends who like games" list. My first thought is, I can get a list of all friends, then for each friend, see if they like any pages with type == "GAMES/TOYS". But ideally, I would like to get the list in one query (not by making one graph API or FQL request per friend). Is this possible, and if so, how?

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• Mimicking Network Databases in SQL

  Unlike the hierarchical database model, which created a tree structure in which to store data, the network model formed a generalized 'graph' structure that describes the relationships between the nodes. Nowadays, the relational model is used to solve the problems for which the network model was created, but the old 'network' solutions are still being implemented by programmers, even when they are less effective.

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• glsl shader to allow color change of skydome ogre3d

  - by Tim

  I'm still very new to all this but learning a lot. I'm putting together an application using Ogre3d as the rendering engine. So far I've got it running, with a simple scene, a day/night cycle system which is working okay. I'm now moving on to looking at changing the color of the skydome material based on the time of day. What I've done so far is to create a struct to hold the ColourValues for the different aspects of the scene. struct todColors { Ogre::ColourValue sky; Ogre::ColourValue ambient; Ogre::ColourValue sun; }; I created an array to store all the colours todColors sceneColours [4]; I populated the array with the colours I want to use for the various times of the day. For instance DayTime (when the sun is high in the sky) sceneColours[2].sky = Ogre::ColourValue(135/255, 206/255, 235/255, 255); sceneColours[2].ambient = Ogre::ColourValue(135/255, 206/255, 235/255, 255); sceneColours[2].sun = Ogre::ColourValue(135/255, 206/255, 235/255, 255); I've got code to work out the time of the day using a float currentHours to store the current hour of the day 10.5 = 10:30 am. This updates constantly and updates the sun as required. I am then calculating the appropriate colours for the time of day when relevant using else if( currentHour >= 4 && currentHour < 7) { // Lerp from night to morning Ogre::ColourValue lerp = Ogre::Math::lerp<Ogre::ColourValue, float>(sceneColours[GT_TOD_NIGHT].sky , sceneColours[GT_TOD_MORNING].sky, (currentHour - 4) / (7 - 4)); } My original attempt to get this to work was to dynamically generate a material with the new colour and apply that material to the skydome. This, as you can probably guess... didn't go well. I know it's possible to use shaders where you can pass information such as colour to the shader from the code but I am unsure if there is an existing simple shader to change a colour like this or if I need to create one. What is involved in creating a shader and material definition that would allow me to change the colour of a material without the overheads of dynamically generating materials all the time? EDIT : I've created a glsl vertex and fragment shaders as follows. Vertex uniform vec4 newColor; void main() { gl_FrontColor = newColor; gl_Position = ftransform(); } Fragment void main() { gl_FragColor = gl_Color; } I can pass a colour to it using ShaderDesigner and it seems to work. I now need to investigate how to use it within Ogre as a material. EDIT : I created a material file like this : vertex_program colour_vs_test glsl { source test.vert default_params { param_named newColor float4 0.0 0.0 0.0 1 } } fragment_program colour_fs_glsl glsl { source test.frag } material Test/SkyColor { technique { pass { lighting off fragment_program_ref colour_fs_glsl { } vertex_program_ref colour_vs_test { } } } } In the code I have tried : Ogre::MaterialPtr material = Ogre::MaterialManager::getSingleton().getByName("Test/SkyColor"); Ogre::GpuProgramParametersSharedPtr params = material->getTechnique(0)->getPass(0)->getVertexProgramParameters(); params->setNamedConstant("newcolor", Ogre::Vector4(0.7, 0.5, 0.3, 1)); I've set that as the Skydome material which seems to work initially. I am doing the same with the code that is attempting to lerp between colours, but when I include it there, it all goes black. Seems like there is now a problem with my colour lerping.

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• Speeding up procedural texture generation

  - by FalconNL

  Recently I've begun working on a game that takes place in a procedurally generated solar system. After a bit of a learning curve (having neither worked with Scala, OpenGL 2 ES or Libgdx before), I have a basic tech demo going where you spin around a single procedurally textured planet: The problem I'm running into is the performance of the texture generation. A quick overview of what I'm doing: a planet is a cube that has been deformed to a sphere. To each side, a n x n (e.g. 256 x 256) texture is applied, which are bundled in one 8n x n texture that is sent to the fragment shader. The last two spaces are not used, they're only there to make sure the width is a power of 2. The texture is currently generated on the CPU, using the updated 2012 version of the simplex noise algorithm linked to in the paper 'Simplex noise demystified'. The scene I'm using to test the algorithm contains two spheres: the planet and the background. Both use a greyscale texture consisting of six octaves of 3D simplex noise, so for example if we choose 128x128 as the texture size there are 128 x 128 x 6 x 2 x 6 = about 1.2 million calls to the noise function. The closest you will get to the planet is about what's shown in the screenshot and since the game's target resolution is 1280x720 that means I'd prefer to use 512x512 textures. Combine that with the fact the actual textures will of course be more complicated than basic noise (There will be a day and night texture, blended in the fragment shader based on sunlight, and a specular mask. I need noise for continents, terrain color variation, clouds, city lights, etc.) and we're looking at something like 512 x 512 x 6 x 3 x 15 = 70 million noise calls for the planet alone. In the final game, there will be activities when traveling between planets, so a wait of 5 or 10 seconds, possibly 20, would be acceptable since I can calculate the texture in the background while traveling, though obviously the faster the better. Getting back to our test scene, performance on my PC isn't too terrible, though still too slow considering the final result is going to be about 60 times worse: 128x128 : 0.1s 256x256 : 0.4s 512x512 : 1.7s This is after I moved all performance-critical code to Java, since trying to do so in Scala was a lot worse. Running this on my phone (a Samsung Galaxy S3), however, produces a more problematic result: 128x128 : 2s 256x256 : 7s 512x512 : 29s Already far too long, and that's not even factoring in the fact that it'll be minutes instead of seconds in the final version. Clearly something needs to be done. Personally, I see a few potential avenues, though I'm not particularly keen on any of them yet: Don't precalculate the textures, but let the fragment shader calculate everything. Probably not feasible, because at one point I had the background as a fullscreen quad with a pixel shader and I got about 1 fps on my phone. Use the GPU to render the texture once, store it and use the stored texture from then on. Upside: might be faster than doing it on the CPU since the GPU is supposed to be faster at floating point calculations. Downside: effects that cannot (easily) be expressed as functions of simplex noise (e.g. gas planet vortices, moon craters, etc.) are a lot more difficult to code in GLSL than in Scala/Java. Calculate a large amount of noise textures and ship them with the application. I'd like to avoid this if at all possible. Lower the resolution. Buys me a 4x performance gain, which isn't really enough plus I lose a lot of quality. Find a faster noise algorithm. If anyone has one I'm all ears, but simplex is already supposed to be faster than perlin. Adopt a pixel art style, allowing for lower resolution textures and fewer noise octaves. While I originally envisioned the game in this style, I've come to prefer the realistic approach. I'm doing something wrong and the performance should already be one or two orders of magnitude better. If this is the case, please let me know. If anyone has any suggestions, tips, workarounds, or other comments regarding this problem I'd love to hear them.

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• Create bullet physics rigid body along the vertices of a blender model

  - by Krishnabhadra

  I am working on my first 3D game, for iphone, and I am using Blender to create models, Cocos3D game engine and Bullet for physics simulation. I am trying to learn the use of physics engine. What I have done I have created a small model in blender which contains a Cube (default blender cube) at the origin and a UVSphere hovering exactly on top of this cube (without touching the cube) I saved the file to get MyModel.blend. Then I used File -> Export -> PVRGeoPOD (.pod/.h/.cpp) in Blender to export the model to .pod format to use along with Cocos3D. In the coding side, I added necessary bullet files to my Cocos3D template project in XCode. I am also using a bullet objective C wrapper. -(void) initializeScene { _physicsWorld = [[CC3PhysicsWorld alloc] init]; [_physicsWorld setGravity:0 y:-9.8 z:0]; /*Setup camera, lamp etc.*/ .......... ........... /*Add models created in blender to scene*/ [self addContentFromPODFile: @"MyModel.pod"]; /*Create OpenGL ES buffers*/ [self createGLBuffers]; /*get models*/ CC3MeshNode* cubeNode = (CC3MeshNode*)[self getNodeNamed:@"Cube"]; CC3MeshNode* sphereNode = (CC3MeshNode*)[self getNodeNamed:@"Sphere"]; /*Those boring grey colors..*/ [cubeNode setColor:ccc3(255, 255, 0)]; [sphereNode setColor:ccc3(255, 0, 0)]; float *cVertexData = (float*)((CC3VertexArrayMesh*)cubeNode.mesh).vertexLocations.vertices; int cVertexCount = (CC3VertexArrayMesh*)cubeNode.mesh).vertexLocations.vertexCount; btTriangleMesh* cTriangleMesh = new btTriangleMesh(); // for (int i = 0; i < cVertexCount * 3; i+=3) { // printf("\n%f", cVertexData[i]); // printf("\n%f", cVertexData[i+1]); // printf("\n%f", cVertexData[i+2]); // } /*Trying to create a triangle mesh that curresponds the cube in 3D space.*/ int offset = 0; for (int i = 0; i < (cVertexCount / 3); i++){ unsigned int index1 = offset; unsigned int index2 = offset+6; unsigned int index3 = offset+12; cTriangleMesh->addTriangle( btVector3(cVertexData[index1], cVertexData[index1+1], cVertexData[index1+2] ), btVector3(cVertexData[index2], cVertexData[index2+1], cVertexData[index2+2] ), btVector3(cVertexData[index3], cVertexData[index3+1], cVertexData[index3+2] )); offset += 18; } [self releaseRedundantData]; /*Create a collision shape from triangle mesh*/ btBvhTriangleMeshShape* cTriMeshShape = new btBvhTriangleMeshShape(cTriangleMesh,true); btCollisionShape *sphereShape = new btSphereShape(1); /*Create physics objects*/ gTriMeshObject = [_physicsWorld createPhysicsObjectTrimesh:cubeNode shape:cTriMeshShape mass:0 restitution:1.0 position:cubeNode.location]; sphereObject = [_physicsWorld createPhysicsObject:sphereNode shape:sphereShape mass:1 restitution:0.1 position:sphereNode.location]; sphereObject.rigidBody->setDamping(0.1,0.8); } When I run the sphere and cube shows up fine. I expect the sphere object to fall directly on top of the cube, since I have given it a mass of 1 and the physics world gravity is given as -9.8 in y direction. But What is happening the spere rotates around cube three or times and then just jumps out of the scene. Then I know I have some basic misunderstanding about the whole process. So my question is, how can I create a physics collision shape which corresponds to the shape of a particular mesh model. I may need complex shapes than cube and sphere, but before going into them I want to understand the concepts.

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• Child transforms problem when loading 3DS models using assimp

  - by MhdSyrwan

  I'm trying to load a textured 3d model into my scene using assimp model loader. The problem is that child meshes are not situated correctly (they don't have the correct transformations). In brief: all the mTansform matrices are identity matrices, why would that be? I'm using this code to render the model: void recursive_render (const struct aiScene *sc, const struct aiNode* nd, float scale) { unsigned int i; unsigned int n=0, t; aiMatrix4x4 m = nd->mTransformation; m.Scaling(aiVector3D(scale, scale, scale), m); // update transform m.Transpose(); glPushMatrix(); glMultMatrixf((float*)&m); // draw all meshes assigned to this node for (; n < nd->mNumMeshes; ++n) { const struct aiMesh* mesh = scene->mMeshes[nd->mMeshes[n]]; apply_material(sc->mMaterials[mesh->mMaterialIndex]); if (mesh->HasBones()){ printf("model has bones"); abort(); } if(mesh->mNormals == NULL) { glDisable(GL_LIGHTING); } else { glEnable(GL_LIGHTING); } if(mesh->mColors[0] != NULL) { glEnable(GL_COLOR_MATERIAL); } else { glDisable(GL_COLOR_MATERIAL); } for (t = 0; t < mesh->mNumFaces; ++t) { const struct aiFace* face = &mesh->mFaces[t]; GLenum face_mode; switch(face->mNumIndices) { case 1: face_mode = GL_POINTS; break; case 2: face_mode = GL_LINES; break; case 3: face_mode = GL_TRIANGLES; break; default: face_mode = GL_POLYGON; break; } glBegin(face_mode); for(i = 0; i < face->mNumIndices; i++)// go through all vertices in face { int vertexIndex = face->mIndices[i];// get group index for current index if(mesh->mColors[0] != NULL) Color4f(&mesh->mColors[0][vertexIndex]); if(mesh->mNormals != NULL) if(mesh->HasTextureCoords(0))//HasTextureCoords(texture_coordinates_set) { glTexCoord2f(mesh->mTextureCoords[0][vertexIndex].x, 1 - mesh->mTextureCoords[0][vertexIndex].y); //mTextureCoords[channel][vertex] } glNormal3fv(&mesh->mNormals[vertexIndex].x); glVertex3fv(&mesh->mVertices[vertexIndex].x); } glEnd(); } } // draw all children for (n = 0; n < nd->mNumChildren; ++n) { recursive_render(sc, nd->mChildren[n], scale); } glPopMatrix(); } What's the problem in my code ? I've added some code to abort the program if there's any bone in the meshes, but the program doesn't abort, this means : no bones, is that normal? if (mesh->HasBones()){ printf("model has bones"); abort(); } Note: I am using openGL & SFML & assimp

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• (CanvsEngine) Collission problem ( TypeError: this._polygon[this._frame] is undefined) [on hold]

  - by user2127102

  How can i fix this error TypeError: this._polygon[this._frame] is undefined Heres my code: html: <!DOCTYPE Html> <head> <meta charset="utf-8"> <title>Project</title> <link href="css/style.css" rel="stylesheet"> <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js" type="text/javascript"></script> <script src="js/canvasengine-1.3.0.all.min.js"></script> <script src="js/extends/Input.js"></script> <script src="main.js"></script> </head> <body> <canvas id="window"></canvas> </body> main.js: var canvas = CE.defines("window"). extend(Input). ready(function() { canvas.Scene.call("Game"); }); canvas.Scene.new({ name: "Game", materials: { images: { player: "img/character.png", Wall: "img/TestWall.png" } }, ready: function(stage) { var _canvas = this.getCanvas(); _canvas.setSize("browser", "strech"); this.Player = Class.new("Entity", [stage]); this.Player.el.drawImage("player"); stage.append(this.Player.el); this.Wall = Class.new("Entity", [stage]); this.Wall.el.drawImage("Wall"); this.Wall.position(300, 0); stage.append(this.Wall.el); }, render: function(stage) { //Controls ====== //Control calculations var self = this; this.Mover_A; this.Mover_D; this.Mover_W; this.Mover_S; canvas.Input.keyDown(Input.A, function(e) { self.Mover_A = true; }); canvas.Input.keyDown(Input.D, function(e) { self.Mover_D = true; }); canvas.Input.keyDown(Input.W, function(e) { self.Mover_W = true; }); canvas.Input.keyDown(Input.S, function(e) { self.Mover_S = true; console.log(self.Mover_S); }); canvas.Input.keyUp(Input.A, function(e) { self.Mover_A = false; }); canvas.Input.keyUp(Input.D, function(e) { self.Mover_D = false; }); canvas.Input.keyUp(Input.W, function(e) { self.Mover_W = false; }); canvas.Input.keyUp(Input.S, function(e) { self.Mover_S = false; }); x = 0; y = 0; if(this.Mover_A)x -= 1.5; //A if(this.Mover_D)x += 1.5;//D if(this.Mover_W)y -= 1.5;//W if(this.Mover_S)y += 1.5; //S this.Player.move(x, y); this.Player.hit("over", [this.Wall], function(state, el) { this.Player.move(x * -1, y * -1); }); //End Controls ===== stage.refresh(); } });

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• Omni-directional light shadow mapping with cubemaps in WebGL

  - by Winged

  First of all I must say, that I have read a lot of posts describing an usage of cubemaps, but I'm still confused about how to use them. My goal is to achieve a simple omni-directional (point) light type shading in my WebGL application. I know that there is a lot more techniques (like using Two-Hemispheres or Camera Space Shadow Mapping) which are way more efficient, but for an educational purpose cubemaps are my primary goal. Till now, I have adapted a simple shadow mapping which works with spotlights (with one exception: I don't know how to cut off the glitchy part beyond the reach of a single shadow map texture): glitchy shadow mapping<<< So for now, this is how I understand the usage of cubemaps in shadow mapping: Setup a framebuffer (in case of cubemaps - 6 framebuffers; 6 instead of 1 because every usage of framebufferTexture2D slows down an execution which is nicely described here <<<) and a texture cubemap. Also in WebGL depth components are not well supported, so I need to render it to RGBA first. this.texture = gl.createTexture(); gl.bindTexture(gl.TEXTURE_CUBE_MAP, this.texture); gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MIN_FILTER, gl.LINEAR); gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MAG_FILTER, gl.LINEAR); for (var face = 0; face < 6; face++) gl.texImage2D(gl.TEXTURE_CUBE_MAP_POSITIVE_X + face, 0, gl.RGBA, this.size, this.size, 0, gl.RGBA, gl.UNSIGNED_BYTE, null); gl.bindTexture(gl.TEXTURE_CUBE_MAP, null); this.framebuffer = []; for (face = 0; face < 6; face++) { this.framebuffer[face] = gl.createFramebuffer(); gl.bindFramebuffer(gl.FRAMEBUFFER, this.framebuffer[face]); gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_CUBE_MAP_POSITIVE_X + face, this.texture, 0); gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, this.depthbuffer); var e = gl.checkFramebufferStatus(gl.FRAMEBUFFER); // Check for errors if (e !== gl.FRAMEBUFFER_COMPLETE) throw "Cubemap framebuffer object is incomplete: " + e.toString(); } Setup the light and the camera (I'm not sure if should I store all of 6 view matrices and send them to shaders later, or is there a way to do it with just one view matrix). Render the scene 6 times from the light's position, each time in another direction (X, -X, Y, -Y, Z, -Z) for (var face = 0; face < 6; face++) { gl.bindFramebuffer(gl.FRAMEBUFFER, shadow.buffer.framebuffer[face]); gl.viewport(0, 0, shadow.buffer.size, shadow.buffer.size); gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT); camera.lookAt( light.position.add( cubeMapDirections[face] ) ); scene.draw(shadow.program); } In a second pass, calculate the projection a a current vertex using light's projection and view matrix. Now I don't know If should I calculate 6 of them, because of 6 faces of a cubemap. ScaleMatrix pushes the projected vertex into the 0.0 - 1.0 region. vDepthPosition = ScaleMatrix * uPMatrixFromLight * uVMatrixFromLight * vWorldVertex; In a fragment shader calculate the distance between the current vertex and the light position and check if it's deeper then the depth information read from earlier rendered shadow map. I know how to do it with a 2D Texture, but I have no idea how should I use cubemap texture here. I have read that texture lookups into cubemaps are performed by a normal vector instead of a UV coordinate. What vector should I use? Just a normalized vector pointing to the current vertex? For now, my code for this part looks like this (not working yet): float shadow = 1.0; vec3 depth = vDepthPosition.xyz / vDepthPosition.w; depth.z = length(vWorldVertex.xyz - uLightPosition) * linearDepthConstant; float shadowDepth = unpack(textureCube(uDepthMapSampler, vWorldVertex.xyz)); if (depth.z > shadowDepth) shadow = 0.5; Could you give me some hints or examples (preferably in WebGL code) how I should build it?

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• Unexplained CPU and Disk activity spikes in SQL Server 2005

  - by Philip Goh

  Before I pose my question, please allow me to describe the situation. I have a database server, with a number of tables. Two of the biggest tables contain over 800k rows each. The majority of rows are less than 10k in size, though roughly 1 in 100 rows will be 1 MB but <4 MB. So out of the 1.6 million rows, about 16000 of them will be these large rows. The reason they are this big is because we're storing zip files binary blobs in the database, but I'm digressing. We have a service that runs constantly in the background, trimming 10 rows from each of these 2 tables. In the performance monitor graph above, these are the little bumps (red for CPU, green for disk queue). Once ever minute we get a large spike of CPU activity together with a jump in disk activity, indicated by the red arrow in the screenshot. I've run the SQL Server profiler, and there is nothing that jumps out as a candidate that would explain this spike. My suspicion is that this spike occurs when one of the large rows gets deleted. I've fed the results of the profiler into the tuning wizard, and I get no optimisation recommendations (i.e. I assume this means my database is indexed correctly for my current workload). I'm not overly worried as the server is coping fine in all circumstances, even under peak load. However, I would like to know if there is anything else I can do to find out what is causing this spike? Update: After investigating this some more, the CPU and disk usage spike was down to SQL server's automatic checkpoint. The database uses the simple recovery model, and this truncates the log file at each checkpoint. We can see this demonstrated in the following graph. As described on MSDN, the checkpoints will occur when the transaction log becomes 70% full and we are using the simple recovery model. This has been enlightening and I've definitely learned something!

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• How should I monitor memory usage/performance in SunOS/Solaris?

  - by exhuma

  Last week we decided to add some SunOS (uname -a = SunOS bbs-sam-belair 5.10 Generic_127128-11 i86pc i386 i86pc) machines into our running munin instance. First off, the machines are pre-configured appliances, so, I want to avoid touching the system too much without supervision of the service provider. But adding it to munin was fairly easy by writing a small socket-service (if anyone is interested, I put it up on github: https://github.com/munin-monitoring/contrib/tree/master/tools/pypmmn) Yesterday, I implemented/adapted the required plugins for our machines. And here the questions start: First, I have not found a way to determine detailed memory usage values. I get the total memory by running prtconf | grep Memory, and the free memory using vmstat. Fiddling together a munin-plugin, gives me the following graph: This is pretty much uninformative. Compare this to the default plugin for linux nodes which has a lot more detail: Most importantly, this shows me how much memory is actually used by applications. So, first question: Is it possible to get detailed memory information on SunOS with the default system tools (i.e. not using top)? Onto the next puzzle: Seeing the graphs, I noticed activity in the "Paging in/out" graphs, even though the memory graph still has unused memory: Upon further investigation, I found out that df reports that /tmp is mounted on swap. Drilling around on the web, I understood that df will display swap, but in fact, it's mounted as a tmpfs. Now I don't know if this explains the swap activity. The default munin-plugin for solaris uses kstat -p -c misc -m cpu_stat to get these values. I find it already strange that this is using the cpu_stat module. So maybe I simply misinterpret the "paging" graphs? Second question: Do the paging graphs indicate that parts of the memory are paged to disk? Or is the activity caused by file operations in /tmp?

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• Free/opensource application for charting stock prices?

  - by Homunculus Reticulli

  I am looking for a free or FOSS software application for SIMPLY charting stock prices. I am not interested in any of the other nonsense typically bundled with such packages (technical analysis, back testing, tracking etc, etc). All I want to do is the following: Import file from CSV and plot on the chart Ability to scroll the chart left/right (zoom feature would be nice to) Ability to draw straight line (between 2 points) on the plot Ability to plot the graph for different resolutions (for e.g weekly, monthly - or some other custom resolution that I want) print the displayed graph (I can always use screen capture if printing is too much to ask) Thats all I want to do. I am not interested in anything else. I would have thought I could have found something by now. I would have written my own tool (I still will do that at a later stage), but I am a bit short of time at the moment, so I just want something that will do all of the above. Can anyone recommend a package. Last but not the least, I am running on Linux (and would prefer to do so - BUT if I have to, I can run on ahem - you know, Windows)

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• Unexplained cache RAM drops on Linux machine

  - by FunkyChicken

  I run a CentOS 5.7 64 machine with 24gb ram and running kernel 2.6.18-274.12.1.el5. This machine runs only Nginx, php-fpm and Xcache as extra applications. Since about 3 weeks my memory behavior on this machine has changed and I cannot explain why. There are no crons running which flush anything like this. There are also no large numbers of files being deleted/changed during these drops. The 'cached' memory gets dropped about every few hours, but it's never a set gap between flushes, this indicates to me that some bottleneck gets reached instead. It also always seems to be when total memory usages gets to about 18GB, but again, not always exactly 18GB. This is a graph of my memory usage: As you can see in the graph the 'buffers' always stay more or less the same, it is mainly the 'cache' that gets dropped. Running vmstat -m I have outputted the memory usage just before and just after a memory drop. The output is here: http://pastebin.com/diff.php?i=hJqZqztm 'old version' being before, 'new version' being after a drop. About 3 weeks ago my server crashed during a heavy DDOS attack, after I rebooted the machine this odd behavior started. I have checked a bunch of logs, restarted the machine again, and cannot find any indication what changed. During these 'cache' memory drops, my iNode usage drops at the same time. Does anyone have any idea what might be causing this behavior? Clearly my RAM isn't full, so I am curious why this could be happening.

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• Looking for a host based network monitor solution

  - by Ole Martin Handeland

  Hi all! Problem So, my hosting company has a network usage graph for my dedicated server. It seems that one day earlier this month, my network usage suddenly spiked with several hundred megabytes transferred (usually it's in the tens, not hundreds). It was probably me, but i just can't be sure who or what it was. Question So my question is; does anyone know of any host based solution for monitoring network usage that would tell me the client's IP-address, the port/service he/she used? What I don't want I'm just guessing that someone will suggest i use nagios, munin, zabbix, cacti, mrtg - I've also looked at those, but a graph over network usage will not give me the answers I'm looking for. :-) Almost there I've already looked at a lot of monitoring solutions, and I've tried [ntop][http://www.ntop.org/], [darkstat][http://unix4lyfe.org/darkstat/] and others. Darkstat just didn't give me the answers. Although it listed a lot of statistics, and i could list the clients - it doesn't show me the network usage for a particular period. Ntop is by far the best I've seen so far - but i think it mostly shows current network usage, not the historical part. I could run apt-get upgrade and download a whole bunch of software, but not see it in the log afterwards.

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• FreeBSD's ng_nat stopping pass the packets periodically

  - by Korjavin Ivan

  I have FreeBSD router: #uname 9.1-STABLE FreeBSD 9.1-STABLE #0: Fri Jan 18 16:20:47 YEKT 2013 It's a powerful computer with a lot of memory #top -S last pid: 45076; load averages: 1.54, 1.46, 1.29 up 0+21:13:28 19:23:46 84 processes: 2 running, 81 sleeping, 1 waiting CPU: 3.1% user, 0.0% nice, 32.1% system, 5.3% interrupt, 59.5% idle Mem: 390M Active, 1441M Inact, 785M Wired, 799M Buf, 5008M Free Swap: 8192M Total, 8192M Free PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND 11 root 4 155 ki31 0K 64K RUN 3 71.4H 254.83% idle 13 root 4 -16 - 0K 64K sleep 0 101:52 103.03% ng_queue 0 root 14 -92 0 0K 224K - 2 229:44 16.55% kernel 12 root 17 -84 - 0K 272K WAIT 0 213:32 15.67% intr 40228 root 1 22 0 51060K 25084K select 0 20:27 1.66% snmpd 15052 root 1 52 0 104M 22204K select 2 4:36 0.98% mpd5 19 root 1 16 - 0K 16K syncer 1 0:48 0.20% syncer Its tasks are: NAT via ng_nat and PPPoE server via mpd5. Traffic through - about 300Mbit/s, about 40kpps at peak. Pppoe sessions created - 350 max. ng_nat is configured by by the script: /usr/sbin/ngctl -f- <<-EOF mkpeer ipfw: nat %s out name ipfw:%s %s connect ipfw: %s: %s in msg %s: setaliasaddr 1.1.%s There are 20 such ng_nat nodes, with about 150 clients. Sometimes, the traffic via nat stops. When this happens vmstat reports a lot of FAIL counts vmstat -z | grep -i netgraph ITEM SIZE LIMIT USED FREE REQ FAIL SLEEP NetGraph items: 72, 10266, 1, 376,39178965, 0, 0 NetGraph data items: 72, 10266, 9, 10257,2327948820,2131611,4033 I was tried increase net.graph.maxdata=10240 net.graph.maxalloc=10240 but this doesn't work. It's a new problem (1-2 week). The configuration had been working well for about 5 months and no configuration changes were made leading up to the problems starting. In the last few weeks we have slightly increased traffic (from 270 to 300 mbits) and little more pppoe sessions (300-350). Help me please, how to find and solve my problem?

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• What is causing sudden freezing during running real-time program?

  - by Trevor Boyd Smith

  So I run a high intensive (CPU/GPU) real-time program. During normal execution suddenly everything freezes for 1-4 seconds. I opened "Process Explorer" in the background to help gain insight and maybe identify something. Here is what the CPU/GPU graphs looks like when I align them in time: Notice the 4 distinct drops in both the CPU/GPU. You can see that it goes from some sort of positive CPU/GPU usage to almost zero. These drops in the graph align with when the real-time program suddenly freezes. How do I find what is causing these sudden drops? NOTE: When you put your mouse over the graph it tells you the time, accurate to the second, for where your cursor is. Maybe this mouse over feature could be helpful in some way (e.g. what if you had a log of all processes every 100ms). EDIT: The real-time program is a video game and so I can't watch some sort of instrumentation while the video game is running. I need a solution that let's you look back in time somehow to see what was happening when the slow down occurred. EDIT: RE - Recording Data vs using real-time monitor: So the windows performance recorder is for some reason not recording what I expect it to record. So I switched to using "perfmon" and then opening it's "resource monitor". RE - Setting it up so I can view real-time monitor: In the video game I set it to spectate and then put the video game in "windowed" mode so that I can view the real time display that Resource Monitor has. Now that I can get semi-real time (only once per second... how do you get more than once per second?) I started looking at the various real time data readouts. Getting to the cause: I noticed a strong correlation in high disk IO and low CPU usage (which is also seen by having in-game freezing). How do you use resource monitor to find out who is doing all this offending disk IO?

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• How do I `SUM` by multiple columns in Excel

  - by dwwilson66

  I have a comma delimited file that includes two columns date/time (which imports as Excel's mm/dd/yyyy hh:mm custom format) and status of 1 or 0. The status represents a piece of equipment either being on or off. I'm trying to generate a graph that will show, hours up vs. down by day. CONSIDER: 1/1/2012 00:00, 1 1/1/2012 03:00, 0 1/1/2012 14:00, 1 1/3/2012 00:00, 0 This tells me that the equipment was up for three hours, down for eleven hours, and then up for thirty-four hours (across two calendar days). However, I would like to generate a graph that shows how many hours PER DAY we were up or down. CONSIDER: 1/1 XXXXXXXXXXXXX----------- (up 13, down 11) 1/2 XXXXXXXXXXXXXXXXXXXXXXXX (up 24) To me, it seems that I need to generate a dataset summing HOURS by STATUS by CALENDAR DAY...but I can't seem to find a flavor of pivot table or nested SUM(IF(SUMIF(...))) combination to make it work. Most troubling is accounting for date changes...in my example above, since my uptime starting at 14:00 on 1/1/2012 crosses midnight, I need to know that 10 uptime hours get totalled with 1/1/2012 and 24 uptime hours get totalled with 1/2/2012. I may be able to do something with a calendar list to drive the date summation, but then I need a way to compare 01/01/2012 to 01/01/2012 03:00 as equal. There's got to be a way along the lines of if(INTEGER-PORTIONS-OF-SERIAL-DATES-ARE-EQUAL,TOTAL-HOURS-IF-VALUE-IS_1,0) but nothing's worked so far. Any suggestions? I've been battling this most of the day, and need a fresh perspective. Thanks

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