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Thread: Does OpenGL have compilable index arrays?

  1. #1
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    Does OpenGL have compilable index arrays?

    I'm not talking about the color index array, but rather a compilable (locking) array of indexed vertices. Basically, is there an OpenGL equivalent to Direct3D Index Buffers that store indices on the graphics hardware memory? I glanced over the spec doc and extentions listing, but I didn't see it.

  2. #2
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    Re: Does OpenGL have compilable index arrays?

    A Google search on "opengl compiled vertex arrays" turned up this as the first result:
    http://www.cs.rit.edu/~ncs/Courses/5...LonWin-18.html

    Hope that helps.

  3. #3
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    Re: Does OpenGL have compilable index arrays?

    OK, my fault for not mentioning this. I've been using locked vertex arrays for some time. That is:
    GL_VERTEX_ARRAY, GL_NORMAL_ARRAY, etc...
    and
    GL_EXT_compiled_vertex_array

    I nearly always use glDrawElements() to render primitives from this array, which means I make arrays of indices to vertex array elements to pass in as the last argument for this function. So I was wondering if there was some sort of array locking functionality for these index arrays that would store them locally on the video hardware for faster processing.

  4. #4
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    Re: Does OpenGL have compilable index arrays?

    Ah, sorry, I misunderstood what you were asking.

    I'm afraid I'm not sure the answer to this question. I'm guessing NVidia's VAR or Ati's VAO might possess the functionality you're looking for, but I don't have experience there. Those would be the first places I would look, though.

    Sorry can't be more helpful.

  5. #5
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    Re: Does OpenGL have compilable index arrays?

    There's no vendor independent way to do this in OpenGL. Do look into the ATI_element_array extension though. I'm not sure if nvidias NV_vertex_array_range2 allows indices in agp/vid mem, but I don't think it does.

  6. #6
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    Re: Does OpenGL have compilable index arrays?

    NV_vertex_array_range2 defines only a token on top of the existing VAR extension; this token allows the app to not flush when enabling/disabling VAR.

    Also, I think I read somewhere (probably on this board) that for ATI cards, indices stored onboard where actually slower than indices stored in system memory. Try a search on this forum.

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