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Type: Posts; User: ugluk

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    3DLabs shader examples

    They used to be hosted on Randi Rost's site, but it is apparently down. Does anyone know where to pull them from now?
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    perspective GUI frustum

    I was thinking about constructing the following perspective frustum:

    l = - w / 2
    r = w / 2
    t = h / 2
    b = - h / 2

    n = w / (2 * tan(HFOV / 2)), f at infinity

    with HFOV = 90 degrees, n = w /...
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    But (GLSL) shaders had their precursors too, if...

    But (GLSL) shaders had their precursors too, if you can call them precursors. Maybe one of those early shading languages influenced the paper.
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    Too bad I haven't thought of this myself....

    Too bad I haven't thought of this myself. Certainly, it's thanks to the shaders, we have this scalar part = w convention. I've written an expression template library (as TVMET is slowly starting to...
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    quaternion indices

    If you check math books, the scalar part of a quaternion is usually at index 0 of a quaternion list, but in some code I've looked up, the scalar part is at index 3. Do there exist any practical...
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    GL viewports & displays

    Does GL offer any way to choose on which display a viewport is to be shown, or is this functionality OS dependent? Here, I mean some game consoles, which offer multiple displays and also the usual...
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    Re: Uploading an image using DevIL: Linker errors

    For some reason many people are unwilling to make the investment of time to learn this. To them this is a command-line thing and they prefer using python or some other scripting language - a pity,...
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    Re: Uploading an image using DevIL: Linker errors

    Yeah, and there's a nifty library called >>tvmet<< for your vector needs :).

    You can also convert to .png, if you don't want to lose quality of your images.
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    Re: Uploading an image using DevIL: Linker errors

    anette, why not give stb_image a try? You can include it in your project without any hassle or downloading of libraries.

    Try this:
    - add the .c file to your project
    - when including the library...
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    Re: Uploading an image using DevIL: Linker errors

    Since she does not know how to compile&amp;link, a simple library like stb_image might do the trick.

    And certainly "uploading" an "image" using DevIL means she's pretty new to GL.
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    Re: Uploading an image using DevIL: Linker errors

    It is a wrapper around libpng, libjpeg, ... and you need to compile&amp;link those.
  12. Thread: GL + timer queue

    by ugluk
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    Re: GL + timer queue

    Yeah, I think after issueCommands() would be a good place.

    Rationale:
    Timer callbacks can alter textures, VBOs ... and might stall the pipeline, if they were called before issueCommands().
  13. Re: Placing many different 2D elements in a window

    glViewport() works for fixed-pipeline GLs all the way to 4.2 and if that is an issue it might be a better solution. I don't think you will notice much of a speed difference between the two methods,...
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    Re: Uploading an image using DevIL: Linker errors

    From my memory DevIL is just a wrapper library. Check http://nothings.org/stb_image.c if you want to rid yourself of linker errors.
  15. Thread: GL + timer queue

    by ugluk
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    GL + timer queue

    If my rendering loop looks like this:

    {
    issueCommands();
    swapBuffers();
    }
    Where is the best place to process a timer queue (processTimerQueue()), before swapping or after? I am pretty...
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    Re: Known minimal OBB database

    The book Real-Time Collision Detection and site provides a good survey of global algorithms.

    The books itself starts with a guess and then proceeds with an empirical optimization algorithm (prone...
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    Re: modelview matrix pairing

    I decompose the modelview and the viewing matrices into a product of matrices M (some arbitrary matrix) and T, a translation matrix.

    The rationale then is, matrix upload is a greater evil than...
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    Re: modelview matrix pairing

    about your world coordinate point, say you have:



    viewing_matrix = M' * T(-view_origin)
    model_matrix = T(model_origin) * M''


    you get:
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    modelview matrix pairing

    Why is the model matrix often "paired" with the viewing matrix in tutorials and examples, such as?


    gl_Position = proj_matrix * (mv_matrix * in_vertex);

    Would there be something wrong, if I...
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    Re: streaming VBO and VAO

    It is about this in addition to holding static data. In a way the VBO is a caching store. Dark Photon's refinement of an earlier Rob Barris' idea.

    I guess an example is in order:


    template...
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    Re: streaming VBO and VAO

    _blitz: yes, I mean the "mutable VAO".

    It seems to me both of you are using your streaming VBO(s) for "true" streaming, i.e. content generated/changed on the CPU and then uploaded to the GPU every...
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    Re: streaming VBO and VAO

    Do you have any bench results comparing the VAO approach with the non-VAO (manual state-setting) approach? I didn't see any bench results when googling, only assertions that using VAOs "should"...
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    Re: Linux PC for OpenGL Development

    Linux systems are particularly good when money _is_ a consideration. For example, you can more easily setup software rendering on Linux, with shader support (GLSL 1.2), than on Windows.

    So, you...
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    streaming VBO and VAO

    Say there are 2 or more VAO, always referring to the same VBO and one binds from one of the VAOs to some other of the VAOs. Is the performance hit less than binding a different VBO (that is, does one...
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    Re: openGL/Facial Expression Recognition

    By "template" she means a meta-model, to which you would assign some parameter values and voila a new face would jump from the meta-model.

    Anette, this is a research-topic and AFAIK, yes, such...
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