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  • How to fix bad Collada produced by FBX?

    - by David
    I tried to use the FBX SDK (2011.3.1) to load FBX files and save them as Collada files in order to be able to import FBX files in Panda3D. Unfortunately the resulting Collada files are not usable for several reasons, among them: There's a Maya specific extra technique diffuse <diffuse> <texture texture="Map__2-image" texcoord="CHANNEL0"> <extra> <technique profile="MAYA"> <wrapU sid="wrapU0">TRUE</wrapU> <wrapV sid="wrapV0">TRUE</wrapV> <blend_mode>ADD</blend_mode> </technique> </extra> </texture> </diffuse> It assigns a texcoord channel name that isn't referenced anywhere else in the file (in the previous code sample, no geometry uses "CHANNEL0"...) Every polygon is exported twice, a first time with a basic material (only diffuse color, specular color, etc.) and a second time with a textured material -- this doubles the number of polygons of each model without any valuable reason Anyway, the resulting Collada file cannot be opened correctly either with OpenCOLLADA or Panda3D's "dae2egg". Anyone has any experience on how to "fix" it and make it understandable by common and well-reputed Collada importers such as OpenCOLLADA?

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  • Windows Azure Recipe: High Performance Computing

    - by Clint Edmonson
    One of the most attractive ways to use a cloud platform is for parallel processing. Commonly known as high-performance computing (HPC), this approach relies on executing code on many machines at the same time. On Windows Azure, this means running many role instances simultaneously, all working in parallel to solve some problem. Doing this requires some way to schedule applications, which means distributing their work across these instances. To allow this, Windows Azure provides the HPC Scheduler. This service can work with HPC applications built to use the industry-standard Message Passing Interface (MPI). Software that does finite element analysis, such as car crash simulations, is one example of this type of application, and there are many others. The HPC Scheduler can also be used with so-called embarrassingly parallel applications, such as Monte Carlo simulations. Whatever problem is addressed, the value this component provides is the same: It handles the complex problem of scheduling parallel computing work across many Windows Azure worker role instances. Drivers Elastic compute and storage resources Cost avoidance Solution Here’s a sketch of a solution using our Windows Azure HPC SDK: Ingredients Web Role – this hosts a HPC scheduler web portal to allow web based job submission and management. It also exposes an HTTP web service API to allow other tools (including Visual Studio) to post jobs as well. Worker Role – typically multiple worker roles are enlisted, including at least one head node that schedules jobs to be run among the remaining compute nodes. Database – stores state information about the job queue and resource configuration for the solution. Blobs, Tables, Queues, Caching (optional) – many parallel algorithms persist intermediate and/or permanent data as a result of their processing. These fast, highly reliable, parallelizable storage options are all available to all the jobs being processed. Training Here is a link to online Windows Azure training labs where you can learn more about the individual ingredients described above. (Note: The entire Windows Azure Training Kit can also be downloaded for offline use.) Windows Azure HPC Scheduler (3 labs)  The Windows Azure HPC Scheduler includes modules and features that enable you to launch and manage high-performance computing (HPC) applications and other parallel workloads within a Windows Azure service. The scheduler supports parallel computational tasks such as parametric sweeps, Message Passing Interface (MPI) processes, and service-oriented architecture (SOA) requests across your computing resources in Windows Azure. With the Windows Azure HPC Scheduler SDK, developers can create Windows Azure deployments that support scalable, compute-intensive, parallel applications. See my Windows Azure Resource Guide for more guidance on how to get started, including links web portals, training kits, samples, and blogs related to Windows Azure.

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  • Implementing Light Volume Front Faces

    - by cubrman
    I recently read an article about light indexed deferred rendering from here: http://code.google.com/p/lightindexed-deferredrender/ It explains its ideas in a clear way, but there was one point that I failed to understand. It in fact is one of the most interesting ones, as it explains how to implement transparency with this approach: Typically when rendering light volumes in deferred rendering, only surfaces that intersect the light volume are marked and lit. This is generally accomplished by a “shadow volume like” technique of rendering back faces – incrementing stencil where depth is greater than – then rendering front faces and only accepting when depth is less than and stencil is not zero. By only rendering front faces where depth is less than, all future lookups by fragments in the forward rendering pass will get all possible lights that could hit the fragment. Can anyone explain how exactly you need to render only front faces? Another question is why do you need the front faces at all? Why can't we simply render all the lights and store the ones that overlap at this pixel in a texture? Does this approach serves as a cut-off plane to discard lights blocked by opaque geometry?

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  • ArchBeat Link-o-Rama for 2012-08-28

    - by Bob Rhubart
    You may be tempted by IaaS, but you should PaaS on that or your database cloud journey will be a short one "The better option [to IaaS] is to rationalize the deployment stack so that VMs are needed only for exceptional cases," says B. R. Clouse. "By settling on a standard operating system and patch level, you create an infrastructure that potentially all of your databases can share. Now, the building block will be database instances or possibly schemas within databases. These components are the platforms on which you will deploy workloads, hence this is known as Platform as a Service (PaaS)." 'Shadow IT' can be the cloud's best friend | David Linthicum "I do not advocate that IT give up control and allow business units to adopt any old technology they want," says Infoworld cloud computing blogger David Linthicum. "However, IT needs to face reality: For the past three decades or so, corporate IT has been slow on the uptake around the use of productive new technologies." Do you agree? 9 ways cloud will impact IT employment | ZDNet ZDNet blogger Joe McKendrick condenses information from a recent report on how cloud computing will impact IT jobs. Number one on the list: New categories of jobs arising from cloud computing, which include "private cloud developers and administrators, departmental liaisons, integration specialists, cloud architects, and compliance specialists." Yeah, that's right, cloud architects. For more on cloud architects, including what you need to up your game to thrive in the cloud, check out "The Role of the Cloud Architect" on the OTN ArchBeat Podcast. Decisions, Decisions: The art, science, and politics of technology selection "When the time comes for a solution architect to make the final decision about the technologies, standards, and other elements that are to be incorporated into a particular project, what factors weigh most heavily on that decision? It comes as no surprise that among the architects I contacted, business needs top the list." Managing Oracle Exalogic Elastic Cloud with Oracle Enterprise Manager Ops Center Anand Akela's byline is on this post, but "Dr. Jürgen Fleischer, Oracle Enterprise Manager Ops Center Engineering" appears at the end of the post, so it's anybody's guess as to who wrote this thing. But the content includes a complete listing of the Exalogic 2.0.1 Tea Break Snippets series written by a member of the Exalogic team who goes by the name "The Old Toxophilist." So maybe the best thing to do here is ignore the names and focus on the very useful conent. Boost your infrastructure with Coherence into the Cloud | Nino Guarnacci Nino Guarnacci describes a use case that involved managing a variety of data caches that process complex queries and parallel computational operations, in order to maintain the caches in a consistent state on different server instances. Thought for the Day "No one hates software more than software developers." — Jeff Atwood Source: SoftwareQuotes

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  • How to convert eps file to a large jpeg image

    - by Anand
    Hello, I am using Linux. I want to convert an eps file to jpeg file. I find that I can use "convert" command. However, the resulting image looks very small. I want to enlarge the jpeg file by -resize option. It seems not to work. The resulting image is a pure black one. Do anyone has the same problem? Here are more details: 1: if I use convert -scale 1000x1000 your.eps your.jpg the resulting image looks like a low quality image. The eps vector image is not scaled properly. 2: if I use convert -geometry 300% your.eps your.jpg I get a pure black image. Here is my phf file: 2shared.com/document/RXl2Be-g/askquestions.html and my eps file: 2shared.com/file/qrmwKegj/askquestions.html Thank you very much for your help!

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  • Does Unity's "Transparent Bumped Specular" translate to "semi-shiny must be semi-transparent"?

    - by Shivan Dragon
    Unity's documentation for the "Transparent Bumped Specular" shader/material-type is simply a concatenation of each of the descriptions for its Transparent and Specular Shaders (and also Bumped, but that doesn't apply to the question): Transparent Properties This shader can make mesh geometry partially or fully transparent by reading the alpha channel of the main texture. In the alpha, 0 (black) is completely transparent while 255 (white) is completely opaque. If your main texture does not have an alpha channel, the object will appear completely opaque. (...) Specular Properties (...) Additionally, the alpha channel of the main texture acts as a Specular Map (sometimes called "gloss map"), defining which areas of the object are more reflective than others. Black areas of the alpha will be zero specular reflection, while white areas will be full specular reflection. To me this translates to: I have a mesh representig a car tire The texture need to be very shiny on the rims parts, and almost not shiny at all for the rubber parts Also since the rim is really complex, (with like cut-out decoretions and such), I will not build that into the mesh, but fake it with transparency in the texture I can't do all this using Unity's "Transparent Bumped Specular" shader, because the "rubber" part of the texture will become semi transparent due to me painting the alpha channel dark-grey (because I want it to also be less shiny). Is this correct? If not, how can I make this work?

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  • How to remove seams from a tile map in 3D?

    - by Grimshaw
    I am using my OpenGL custom engine to render a tilemap made with Tiled, using a well spread tileset from the web. There is nothing fancy going on. I load the TMX file from Tiled and generate vertex arrays and index arrays to render the tilemap. I am rendering this tilemap as a wall in my 3D world, meaning that I move around with a fly camera in my 3D world and at Z=0 there is a plane showing me my tiles. Everything is working correctly but I get ugly seems between the tiles. I've tried orthographic and perspective cameras and with either I found particular sets of parameters for the projection and view matrices where the artifacts did not show, but otherwise they are there 99% of the time in multiple patterns, depending on the zoom and camera parameters like field of view. Here's a screenshot of the artifact being shown: http://i.imgur.com/HNV1g4M.png Here's the tileset I am using (which Tiled also uses and renders correctly): http://i.imgur.com/SjjHK4q.png My tileset has no mipmaps and is set to GL_NEAREST and GL_CLAMP_TO_EDGE values. I've looked around many articles in the internet and nothing helped. I tried uv correction so the uv fall at half of the texel, rather than the end of the texel to prevent interpolating with the neighbour value(which is transparency). I tried debugging with my geometry and I verified that with no texture and a random color in each tile, I don't seem to see any seams. All vertices have integer coordinates, i.e, the first tile is a quad from (0,0) to (1,1) and so on. Tried adding a little offset both to the UV and to the vertices to see if the gaps cease to exist. Disabled multisampling too. Nothing fixed it so far. Thanks.

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  • Static "LoD" hack opinions

    - by David Lively
    I've been playing with implementing dynamic level of detail for rendering a very large mesh in XNA. It occurred to me that (duh) the whole point of this is to generate small triangles close to the camera, and larger ones far away. Given that, rather than constantly modifying or swapping index buffers based on a feature's rendered size or distance from the camera, it would be a lot easier (and potentially quite a bit faster), to render a single "fan" or flat wedge/frustum-shaped planar mesh that is tessellated into small triangles close to the near or small end of the frustum and larger ones at the far end, sort of like this (overhead view) (Pardon the gap in the middle - I drew one side and mirrored it) The triangle sizes are chosen so that all are approximately the same size when projected. Then, that mesh would be transformed to track the camera so that the Z axis (center vertical in this image) is always aligned with the view direction projected into the XZ plane. The vertex shader would then read terrain heights from a height texture and adjust the Y coordinate of the mesh to match a height field that defines the terrain. This eliminates the need for culling (since the mesh is generated to match the viewport dimensions) and the need to modify the index and/or vertex buffers when drawing the terrain. Obviously this doesn't address terrain with overhangs, etc, but that could be handled to a certain extent by including a second mesh that defines a sort of "ceiling" via a different texture. The other LoD schemes I've seen aren't particularly difficult to implement and, in some cases, are a lot more flexible, but this seemed like a decent quick-and-dirty way to handle height map-based terrain without getting into geometry manipulation. Has anyone tried this? Opinions?

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  • How to recover from terminal custom setup

    - by linq
    I installed ubuntu 12.04 and I added "Terminal" to the launcher bar, the default size of the terminal is a bit small, after some googling here is how I made the disaster change: At HUD menu, type "preference" and I see the option of Edit > preference, this is as I expected After I clicked the option, I forget the exact steps, but somehow I came to some configuration panel and there is a checkbox for terminal "custom" and I checked it now an input box is enabled and I type gnome-terminal --geometry 160x50 Now the problem comes, whenever I click the terminal button at the launcher bar, new terminal windows pops up endlessly from everywhere, I cannot do anything any more except logout or shutdown. The weird thing is, after I come back, I cannot get that Edit > preference any more when I type "preference" in HUD, I tried "Edit", "preference". To be clear, I still can use the computer as long as I do not click that terminal button, but I really want to use terminal to run commands. Help is appreciated greatly! Update - OK, figured out. Go to /home/jibin/.gconf/apps/gnome-terminal/profiles/Default and open that xml file, I can see the options I changed at the GUI, remove them and terminal runs good. The preference HUD is back also, it is actually Profile Preference and it is only available when terminal is open. Continue my ubuntu-ing...

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  • Mapping dynamic buffers in Direct3D11 in Windows Store apps

    - by Donnie
    I'm trying to make instanced geometry in Direct3D11, and the ID3D11DeviceContext1->Map() call is failing with the very helpful error of "Invalid Parameter" when I'm attempting to update the instance buffer. The buffer is declared as a member variable: Microsoft::WRL::ComPtr<ID3D11Buffer> m_instanceBuffer; Then I create it (which succeeds): D3D11_BUFFER_DESC instanceDesc; ZeroMemory(&instanceDesc, sizeof(D3D11_BUFFER_DESC)); instanceDesc.Usage = D3D11_USAGE_DYNAMIC; instanceDesc.ByteWidth = sizeof(InstanceData) * MAX_INSTANCE_COUNT; instanceDesc.BindFlags = D3D11_BIND_VERTEX_BUFFER; instanceDesc.CPUAccessFlags = D3D11_CPU_ACCESS_WRITE; instanceDesc.MiscFlags = 0; instanceDesc.StructureByteStride = 0; DX::ThrowIfFailed(d3dDevice->CreateBuffer(&instanceDesc, NULL, &m_instanceBuffer)); However, when I try to map it: D3D11_MAPPED_SUBRESOURCE inst; DX::ThrowIfFailed(d3dContext->Map(m_instanceBuffer.Get(), 0, D3D11_MAP_WRITE, 0, &inst)); The map call fails with E_INVALIDARG. Nothing is NULL incorrectly, and this being one of my first D3D apps I'm currently stumped on what to do next to track it down. I'm thinking I must be creating the buffer incorrectly, but I can't see how. Any input would be appreciated.

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  • AutoVue 20.2 for Agile Released

    - by Angus Graham
    Normal 0 false false false EN-CA X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif";} Oracle’s AutoVue 20.2 for Agile PLM is now available on Oracle’s Software Delivery Cloud. This latest release allows Agile PLM customers to take advantage of new AutoVue 20.2 features in the following Agile PLM environments: 9.3.1.x; 9.3.0.  AutoVue 20.2 delivers improvements in the following areas. New Format Support: AutoVue 20.2 adds support for the latest versions of popular file formats including: ECAD: Cadence Concept HDL 16.5, Allegro Layout 16.5, Orcad Capture 16.5, Board Station ASCII Symbol Geometry, Cadence Cell Library MCAD: CATIA V5 R21, PTC Creo Parametric 1.0, Creo Element\Direct Modeling 17.10, 17.20, 17.25, 17.30, 18.00, SolidWorks 2012, SolidEdge ST3 & ST4, PLM XML 2D CAD: Creo Element/Direct Drafting 17.10 to 18.00 Office: MS Office 2010: Word, Excel, PowerPoint, Outlook Enhancements to AutoVue enterprise readiness: reliability and performance improvements, as well as security enhancements which adhere to Oracle’s Software Security Assurance standards Updated version of AutoVue Document Print Service offerings, which include the ability to select CAD layers for printing  For further details, check out the What’s New in AutoVue 20.2 datasheet

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  • What is the correct and most efficient approach of streaming vertex data?

    - by Martijn Courteaux
    Usually, I do this in my current OpenGL ES project (for iOS): Initialization: Create two VBO's and one IndexBuffer (since I will use the same indices), same size. Create two VAO's and configure them, both bound to the same Index Buffer. Each frame: Choose a VBO/VAO couple. (Different from the previous frame, so I'm alternating.) Bind that VBO Upload new data using glBufferSubData(GL_ARRAY_BUFFER, ...). Bind the VAO Render my stuff using glDrawElements(GL_***, ...); Unbind the VAO However, someone told me to avoid uploading data (step 3) and render immediately the new data (step 5). I should avoid this, because the glDrawElements call will stall until the buffer is effectively uploaded to VRAM. So he suggested to draw all my geometry I uploaded the previous frame and upload in the current frame what will be drawn in the next frame. Thus, everything is rendered with the delay of one frame. Is this true or am I using the good approach to work with streaming vertex data? (I do know that the pipeline will stall the other way around. Ie: when you draw and immediately try to change the buffer data. But I'm not doing that, since I implemented double buffering.)

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  • GDM login screen is not displayed with VNC

    - by niboshi
    Hi, I set up VNC server with xinetd. Also configured GDM so that XDMCP is enabled. VNC connection seems okay, but GDM login screen is not shown. Instead I can only see old bare X screen (gray meshed background and X-shaped mouse pointer), which I can't do any interaction with it. What can I do to fix the problem? No log is written below /var/log/. Server distribution: Ubuntu marverick /etc/xinetd.d/vnc is like below: service vnc1024 { disable = no socket_type = stream protocol = tcp wait = no user = nobody server = /usr/bin/Xvnc server_args = -inetd -query localhost -geometry 1024x768 -depth 24 -once securitytypes=none port = 12345 } /etc/gdm/custom.conf: [daemon] [security] DisallowTCP=false [xdmcp] Enable=true [gui] [greeter] [chooser] [debug] [servers] /etc/services is also configured. Thanks

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  • Method for spawning enemies according to player score and game time

    - by Sun
    I'm making a top-down shooter and want to scale the difficulty of the game according to what the score is and how much time has Passed. Along with this, I want to spawn enemies in different patterns and increase the intervals at which these enemies are shown. I'm going for a similar effect to Geometry wars. However, I can think of a to do this other than have multiple if-else statments, e.g. : if (score > 1000) { //spawn x amount if enemies } else if (score > 10000) { //spawn x amount of enemy type 1 & 2 } else if (score > 15000) { //spawn x amount of enemy type 1 & 2 & 3 } else if (score > 25000) { //spawn x amount of enemy type 1 & 2 & 3 //create patterns with enemies } ...etc What would be a better method of spawning enemies as I have described?

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  • Bounding volume hierarchy - linked nodes (linear model)

    - by teodron
    The scenario A chain of points: (Pi)i=0,N where Pi is linked to its direct neighbours (Pi-1 and Pi+1). The goal: perform efficient collision detection between any two, non-adjacent links: (PiPi+1) vs. (PjPj+1). The question: it's highly recommended in all works treating this subject of collision detection to use a broad phase and to implement it via a bounding volume hierarchy. For a chain made out of Pi nodes, it can look like this: I imagine the big blue sphere to contain all links, the green half of them, the reds a quarter and so on (the picture is not accurate, but it's there to help understand the question). What I do not understand is: How can such a hierarchy speed up computations between segments collision pairs if one has to update it for a deformable linear object such as a chain/wire/etc. each frame? More clearly, what is the actual principle of collision detection broad phases in this particular case/ how can it work when the actual computation of bounding spheres is in itself a time consuming task and has to be done (since the geometry changes) in each frame update? I think I am missing a key point - if we look at the picture where the chain is in a spiral pose, we see that most spheres are already contained within half of others or do intersect them.. it's odd if this is the way it should work.

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  • Deferred Rendering With Diffuse,Specular, and Normal maps

    - by John
    I have been reading up on deferred rendering and I am trying to implement a renderer using the Sponza atrium model, which can be found here, as my sandbox.Note I am also using OpenGL 3.3 and GLSL. I am loading the model from a Wavefront OBJ file using Assimp. I extract all geometry information including tangents and bitangents. For all the aiMaterials,I extract the following information which essentially comes from the sponza.mtl file. Ambient/Diffuse/Specular/Emissive Reflectivity Coefficients(Ka,Kd,Ks,Ke) Shininess Diffuse Map Specular Map Normal Map I understand that I must render vertex attributes such as position ,normals,texture coordinates to textures as well as depth for the second render pass. A lot of resources mention putting colour information into a g-buffer in the initial render pass but do you not require the diffuse,specular and normal maps and therefore lights to determine the fragment colour? I know that doesnt make since sense because lighting should be done in the second render pass. In terms of normal mapping, do you essentially just pass the tangent,bitangents, and normals into g-buffers and then construct the tangent matrix and apply it to the sampled normal from the normal map. Ultimately, I would like to know how to incorporate this material information into my deferred renderer.

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  • OpenGL sprites and point size limitation

    - by Srdan
    I'm developing a simple particle system that should be able to perform on mobile devices (iOS, Andorid). My plan was to use GL_POINT_SPRITE/GL_PROGRAM_POINT_SIZE method because of it's efficiency (GL_POINTS are enough), but after some experimenting, I found myself in a trouble. Sprite size is limited (to usually 64 pixels). I'm calculating size using this formula gl_PointSize = in_point_size * some_factor / distance_to_camera to make particle sizes proportional to distance to camera. But at some point, when camera is close enough, problem with size limitation emerges and whole system starts looking unrealistic. Is there a way to avoid this problem? If no, what's alternative? I was thinking of manually generating billboard quad for each particle. Now, I have some questions about that approach. I guess minimum geometry data would be four vertices per particle and index array to make quads from these vertices (with GL_TRIANGLE_STRIP). Additionally, for each vertex I need a color and texture coordinate. I would put all that in an interleaved vertex array. But as you can see, there is much redundancy. All vertices of same particle share same color value, and four texture coordinates are same for all particles. Because of how glDrawArrays/Elements works, I see no way to optimise this. Do you know of a better approach on how to organise per-particle data? Should I use buffers or vertex arrays, or there is no difference because each time I have to update all particles' data. About particles simulation... Where to do it? On CPU or on a vertex processors? Something tells me that mobile's CPU would do it faster than it's vertex unit (at least today in 2012 :). So, any advice on how to make a simple and efficient particle system without particle size limitation, for mobile device, would be appreciated. (animation of camera passing through particles should be realistic)

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  • Lighting with VBO

    - by nkint
    I'm using a Java JOGL wrapper called processing.org. I have coded some enviroment on it and I'm quite proud of it even if it has some ready stuffs that I didn't know anything about it (==LIGHTS). Then, for some geometry, I've decided to use a VBO. I had to pass in the hard way and recode all lights. But I can't achieve the same result. This is the original light system: And this with VBO: With this code: Vec3D l; gl.glEnable(GL.GL_LIGHTING); gl.glEnable(GL.GL_LIGHT0); gl.glEnable(GL.GL_COLOR_MATERIAL); gl.glMaterialfv(GL.GL_FRONT_AND_BACK, GL.GL_AMBIENT, new float[]{0.8f,0f,0f}, 0); l = new Vec3D(0,0,-10); gl.glColor3f(0.8f,0f,0f); gl.glLightfv(GL.GL_LIGHT0, GL.GL_POSITION, new float[] { l.x, l.y, l.z, 0 }, 0); gl.glLightfv(GL.GL_LIGHT0, GL.GL_SPOT_DIRECTION, new float[] { 1, 1, 1, 1 }, 0); I can't achive the same light, the same color material, and the same wireframe stuffs. If needed I can also post the code I use for VBO, but it is quite standard vertex array grabbed on the net that uses glDrawArrays

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  • design a model for a system of dependent variables

    - by dbaseman
    I'm dealing with a modeling system (financial) that has dozens of variables. Some of the variables are independent, and function as inputs to the system; most of them are calculated from other variables (independent and calculated) in the system. What I'm looking for is a clean, elegant way to: define the function of each dependent variable in the system trigger a re-calculation, whenever a variable changes, of the variables that depend on it A naive way to do this would be to write a single class that implements INotifyPropertyChanged, and uses a massive case statement that lists out all the variable names x1, x2, ... xn on which others depend, and, whenever a variable xi changes, triggers a recalculation of each of that variable's dependencies. I feel that this naive approach is flawed, and that there must be a cleaner way. I started down the path of defining a CalculationManager<TModel> class, which would be used (in a simple example) something like as follows: public class Model : INotifyPropertyChanged { private CalculationManager<Model> _calculationManager = new CalculationManager<Model>(); // each setter triggers a "PropertyChanged" event public double? Height { get; set; } public double? Weight { get; set; } public double? BMI { get; set; } public Model() { _calculationManager.DefineDependency<double?>( forProperty: model => model.BMI, usingCalculation: (height, weight) => weight / Math.Pow(height, 2), withInputs: model => model.Height, model.Weight); } // INotifyPropertyChanged implementation here } I won't reproduce CalculationManager<TModel> here, but the basic idea is that it sets up a dependency map, listens for PropertyChanged events, and updates dependent properties as needed. I still feel that I'm missing something major here, and that this isn't the right approach: the (mis)use of INotifyPropertyChanged seems to me like a code smell the withInputs parameter is defined as params Expression<Func<TModel, T>>[] args, which means that the argument list of usingCalculation is not checked at compile time the argument list (weight, height) is redundantly defined in both usingCalculation and withInputs I am sure that this kind of system of dependent variables must be common in computational mathematics, physics, finance, and other fields. Does someone know of an established set of ideas that deal with what I'm grasping at here? Would this be a suitable application for a functional language like F#? Edit More context: The model currently exists in an Excel spreadsheet, and is being migrated to a C# application. It is run on-demand, and the variables can be modified by the user from the application's UI. Its purpose is to retrieve variables that the business is interested in, given current inputs from the markets, and model parameters set by the business.

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  • Game Review: Monument Valley

    Once again, it was a tweet that caught my attention... and the official description on the Play Store sounds good, too. "In Monument Valley you will manipulate impossible architecture and guide a silent princess through a stunningly beautiful world. Monument Valley is a surreal exploration through fantastical architecture and impossible geometry. Guide the silent princess Ida through mysterious monuments, uncovering hidden paths, unfolding optical illusions and outsmarting the enigmatic Crow People." So, let's check it out. What an interesting puzzle game Once again, I left some review on the Play Store: "Beautiful but short distraction Woohoo, what a great story behind the game. Using optical illusions and impossible geometries in this fantastic adventure of the silent princess just puts all the pieces perfectly together. Walking the amazing paths in the various levels and solving the riddles gives some decent hours of distraction but in the end you might have the urge to do more..." I can't remember exactly when and who tweeted about the game but honestly it caught my attention based on the simplicity of the design and the aspect that it seems to be an isometric design. The game relies heavily on optical illusions in order to guide to the silent princess Ida through her illusory adventure of impossible architecture and forgiveness. The game is set like a clockwork and you are turning, flipping and switching elements on the paths between the doors. Unfortunately, there aren't many levels and the game play lasted only some hours. Maybe there are more astonishing looking realms and interesting gimmicks in future versions. Play Store: Monument Valley Also, check out the latest game updates on the official web site of ustwo BTW, the game is also available on the Apple App Store and on Amazon Store for the Kindle Fire.

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  • Trying to recover deleted Ubuntu partition

    - by user110984
    I made a mistake in logging into my 200 GB Ubuntu partition. I could not access Grub after that. Using a live CD I then ran Boot_Repair and apparently deleted the partition, I guess because I ran it from my 70 GB Windows partition. I can send the results of boot_info before that and of Boot_Repair. Then I ran TestDisk, which apparently found only dev/sda/ -320GB / 298 / GiB - WDC - WD3200BEVT-22A23T0 (Was there any more I could have done with TestDisk? I looked at the TestDisk_Step_By_Step example and found no way forward given that no other partitions turned up) I have run gpart and found this: /sda1 - 15 GB /sda2 - system reserved /sda3 - 70.15 GB /sda4 - extended 212.84 unallocated - 209.10 /sda5 - unknown 3.74 . I have been told I can recover the partition using gparted's Rescue start end command, but I don't know what to enter for start and end. [--EDIT: TestDisk Deeper Search stated that "the following partitions can't be recovered" and listed a 220-GB Linux partition 6 times. Then it stated that "The current number of heads per cylinder is 255 but the correct value may be 128" and I could try to change it in the Geometry menu (because apparently these are overlapping partitions) So should I do that?--]

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  • How employable am I as a programmer?

    - by dsimcha
    I'm currently a Ph.D. student in Biomedical Engineering with a concentration in computational biology and am starting to think about what I want to do after graduate school. I feel like I've accumulated a lot of programming skills while in grad school, but taken a very non-traditional path to learning all this stuff. I'm wondering whether I would have an easy time getting hired as a programmer and could fall back on that if I can't find a good job directly in my field, and if so whether I would qualify for a more prestigious position than "code monkey". Things I Have Going For Me Approximately 4 years of experience programming as part of my research. I believe I have a solid enough grasp of the fundamentals that I could pick up new languages and technologies pretty fast, and could demonstrate this in an interview. Good math and statistics skills. An extensive portfolio of open source work (and the knowledge that working on these projects implies): I wrote a statistics library in D, mostly from scratch. I wrote a parallelism library (parallel map, reduce, foreach, task parallelism, pipelining, etc.) that is currently in review for adoption by the D standard library. I wrote a 2D plotting library for D against the GTK Cairo backend. I currently use it for most of the figures I make for my research. I've contributed several major performance optimizations to the D garbage collector. (Most of these were low-hanging fruit, but it still shows my knowledge of low-level issues like memory management, pointers and bit twiddling.) I've contributed lots of miscellaneous bug fixes to the D standard library and could show the change logs to prove it. (This demonstrates my ability read other people's code.) Things I Have Going Against Me Most of my programming experience is in D and Python. I have very little to virtually no experience in the more established, "enterprise-y" languages like Java, C# and C++, though I have learned a decent amount about these languages from small, one-off projects and discussions about language design in the D community. In general I have absolutely no knowledge of "enterprise-y" technlogies. I've never used a framework before, possibly because most reusable code for scientific work and for D tends to call itself a "library" instead. I have virtually no formal computer science/software engineering training. Almost all of my knowledge comes from talking to programming geek friends, reading blogs, forums, StackOverflow, etc. I have zero professional experience with the official title of "developer", "software engineer", or something similar.

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  • When mapping the surface of a sphere with tiles, how might you deal with polar distortion?

    - by clweeks
    It's easy to deal with the way locations interact on a clean Cartesian grid. It's just vanilla math. And you can kind of ignore the geometry of the sphere's surface for a bunch of it if you want to just truncate the poles or something. But I keep coming up with ideas for games where the polar space matters. Geo-coded ARGs and global roguelikes and stuff. I want square(ish?) locations -- reasonably representable by square tiles of the same size across the globe, anyway. This has to be a solved problem, right? What are the solutions? ETA: At the equator -- and assuming that your square locations are reasonably small, it's close enough to true that you can get away with having one square in the rows north and south of the most equatorial row. And you could probably get away with that by just hand-waving the difference up to like 45-degrees or so. But eventually, you need to have fewer squares in a pole-ward circumferential row. If I reduce the length of the row by one and offset the squares by 1/2 then they're just like hexes and it's relatively easy to do the coding to keep track of the connections. But as you get pole-ward, it gets more and more extreme. Projecting the surface of the world onto the surface of a cube is tempting. But I figured there must be more elegant solutions already in use. If I did the cube thing (not dissecting it further through geodesy) Are there any pros and cons related to placing the pole at the center of a face or at the vertex of three sides?

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  • Deferred rendering order?

    - by Nick Wiggill
    There are some effects for which I must do multi-pass rendering. I've got the basics set up (FBO rendering etc.), but I'm trying to get my head around the most suitable setup. Here's what I'm thinking... The framebuffer objects: FBO 1 has a color attachment and a depth attachment. FBO 2 has a color attachment. The render passes: Render g-buffer: normals and depth (used by outline & DoF blur shaders); output to FBO no. 1. Render solid geometry, bold outlines (as in toon shader), and fog; output to FBO no. 2. (can all render via a single fragment shader -- I think.) (optional) DoF blur the scene; output to the default frame buffer OR ELSE render FBO2 directly to default frame buffer. (optional) Mesh wireframes; composite over what's already in the default framebuffer. Does this order seem viable? Any obvious mistakes?

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  • Gnome - windows always open top left

    - by BobTodd
    I find this a highly annoying "feature" on a wide screen monitor that my mostly used apps - terminal and gedit always open directly under the top-left corner of my screen and I have to drag them to my eye position each and every-time. I have tried installing the CompizConfig Settings Manager and using the feature to position windows centre, but this has had no effect - the force feature here isn't working for me either. I can use e.g. gnome-terminal --geometry=140x50+50+50 for the terminal but this doesn't work for gedit. Any ideas? Thanks

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