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Type: Posts; User: Baughn

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    Re: Converting to 3.3

    Sure. I'm not sure I understand, though; if the input coordinates were out of whack in that way, shouldn't the 4000-something triangles get drawn as a single dot in the center of the screen, instead...
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    Re: Converting to 3.3

    I suppose that covers the deprecated bit, yep. No ideas about the actual problem I was facing, then? It /is/ pretty bizarre, I guess..

    Out of curiosity, what would happen if I bound multiple out...
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    Converting to 3.3

    I'm attempting to convert some code I've got to OpenGL 3.3, core profile, with little success.

    Currently, I'm trying to render a 2D grid of triangles. Just that; nothing fancy, no texture-mapping,...
  4. Thread: Testing shaders

    by Baughn
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    Re: Testing shaders

    Oh, well.

    I did find that one, but I should probably mention - it needs to work in Linux. I don't have a Windows license anywhere.
  5. Thread: Testing shaders

    by Baughn
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    Testing shaders

    When writing shaders, I often find that what works on one card does not work on another. Specifically, since I'm using nvidia everywhere, users with ATI usually end up suffering.

    The obvious...
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    Re: VBOs strangely slow?

    Naturally, trying to use display lists ran into the problem that my vertex shader uses gl_VertexID, which appears not to be set when executing display lists.

    Is there a reasonable alternative?...
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    Re: VBOs strangely slow?

    I'm afraid all these details are too much for this poor systems programmer. I'll play the ouija board, figure out code that works well on my own system, and not worry too much about other systems....
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    Re: VBOs strangely slow?

    That's pretty much the idea. I don't actually update the array here (because I just want to benchmark transfer speed, not random-number generation), but the target program writes new data every...
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    Re: VBOs strangely slow?

    I tried it (I think?), just uncomment the glBufferSubData line in the paste.. no difference.
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    Re: VBOs strangely slow?

    In the end, glMapBuffer was (much) faster; preceding it with a glBufferData with a null pointer (discarding its contents), 10% faster than the vertex array.

    All's well that ends well? I guess, but...
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    Re: VBOs strangely slow?

    I was testing various combinations to see what, if anything, had an effect. So far nothing's produced any change at all.

    Fixing the non-VBO case so the entire array is actually used, I'm looking...
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    Re: VBOs strangely slow?

    Orr it could be because the lowermost program actually transfers far less data. Um. Yeah.

    Though even with that fixed, VBOs are /still/ 40% slower.
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    Re: VBOs strangely slow?

    Yes, all _DRAW permutations have been tested; they make no apparent difference. (STATIC_DRAW was no slower, even.. you'd think it would be)

    I also tested bufferSubData vs. bufferData in those...
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    VBOs strangely slow?

    I have here two short programs doing the same thing, namely drawing random points on the screen.

    The first one uses VBOs; the second, OpenGL 1.1 drawArrays. There are a couple parameters to play...
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