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Type: Posts; User: AlexN

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    This is the same behavior I observed six years...

    This is the same behavior I observed six years ago while trying to use three NV Quadro GPUs in a single system. I reported it to NVIDIA, who mentioned something about their OpenGL driver serializing...
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    The geometry shader isn't designed to produce...

    The geometry shader isn't designed to produce enough output triangles quickly enough to be used for that kind of detail tessellation. It has an upper limit on how many output triangles per input...
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    Sounds similar to my experience with AMD and...

    Sounds similar to my experience with AMD and glGenerateMipmap. I had to do something like calling glGenerateMipmap once at texture creation just to get things into a good state, and then again later...
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    It was used in Crysis, and probably a couple...

    It was used in Crysis, and probably a couple others. There have been some papers released with variations on the original technique that use acceleration structures to speed up the ray cast (distance...
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    Looks like it was added in GL 4.2 core for...

    Looks like it was added in GL 4.2 core for compatibility with OpenGL ES 2 (though... I don't think GL_FIXED has been a fast path since the original OpenGL ES 1.x devices).

    Here's the original...
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    Try disabling mipmapping for the texture(s) you...

    Try disabling mipmapping for the texture(s) you are ray casting against. If the problem remains, that will at least rule out texcoord gradient calculation as a problem.
  7. Is the overlapping region a single pixel wide, or...

    Is the overlapping region a single pixel wide, or is it sometimes a couple pixels wide and blocky? If a single pixel, that sounds like a precision issue. If more than one pixel and blocky, it's...
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    Re: ATI 11.11 bug with stencil routing k-buffer

    My understanding is that he's rendering 4 quads on top of each other, and expecting each quad to go into a different slot (MSAA buffer sample) by using sample masking. Sample shading shouldn't matter...
  9. Re: Map range flags / Buffer usage - Nvidia drivers

    The NVIDIA driver most likely sees that you are mapping the buffer more than once and moves it to a different type of memory, which has lower performance for drawing, but supposedly faster...
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    Re: Native Multiple GPU Support

    It's actually quite simple on Linux. You can set up each GPU to be its own X screen.

    Then you just set DISPLAY=:0.# (where # is the screen number) before you create your GL context. Simple. ...
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    Re: Native Multiple GPU Support

    It would be nice to have a vendor-neutral way of creating a context assigned to a specific GPU, and as an added bonus to provide an API to copy data between GPUs. Direct3D has supported this for a...
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    Re: Point antialiasing and gl_PointSize

    If you need consistent behavior, you'll be better off using point sprites or quads with a round texture.

    I believe POINT_SMOOTH is for smoothing points when multisampling is disabled, and I...
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    Re: Coloring picking id out of render buffer?

    That's a perfectly valid way of doing it. I would avoid using integer data types in your shader if you are targeting GL 2.1 and GL ES 2.0, and send a vec4 into your vertex shader as the ID. You can...
  14. Re: Compiling/linking shaders on a thread on NVIDIA

    NVIDIA's OpenGL drivers have quite a bit of locking in them that has prevented me from seeing any gains from a multithreaded renderer (using the GPU affinity extension). I've had a bug open with them...
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    Re: Stencil routed A-buffer (explict_multisample)

    For what it's worth, I had to use a screen aligned quad as well, because glClear doesn't respect the sample mask (or, if it's supposed to, it doesn't in practice).
  16. Re: Can't disable multisampling w/ multisample texture

    I get the same behavior on a Quadro FX 5800 with driver 197.44. With multisampling disabled, the sample position changes after every 4th sample... so, samples 0-3 are in the same position, 4-7 are in...
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    Re: Stencil routed A-buffer (explict_multisample)

    Perhaps it is a bug in the driver you are using, because glDisable(GL_MULTISAMPLE) does cause the sample to be rasterized at the pixel center and then broadcast to each sub-sample, with the stencil...
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    Re: glDrawElementsInstanced and textures

    Yes, you can create a 3D texture of size 1024x1024x5. But, what you are probably looking for are 2D texture arrays.

    http://www.opengl.org/registry/specs/EXT/texture_array.txt
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    Re: Primitive restart vs multi-draw calls?

    Primitive restart should be faster. But, are you sure you need it? It's only useful for quad, triangle, or line strips, I believe... And, the typical usage of putting multiple triangle strips into a...
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    Re: experiences rendering instances

    When instanced drawing was first made available, I saw similar results where instancing was actually slower than pseudo-instancing. Over time, drivers seem to have improved and now the exact same...
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    Re: NVIDIA releases OpenGL 4.0 drivers

    I didn't report this one, but it looks like 197.44 fixes a GLSL bug where breaking out of a for loop would increment the loop counter an additional time.
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    Re: Readback speeds of newest cards?

    For the 5850, under Win7 on X58 platform I get 4.15 GB/s upload and 750 mb/s (850 on second GPU) peak readback and 550 average readback (larger block sizes).
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    Re: Readback speeds of newest cards?

    I'm measuring from the CPU's perspective, using glFinish before and after. For texture uploads I force the upload to complete by issuing a small draw call using the texture, as well.

    I'm not using...
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    Re: Readback speeds of newest cards?

    Here are some numbers, tested under Windows 7 in OpenGL with 1mb transfer sizes (512x512x4):

    Radeon 5850
    cpu -> gpu, glDrawPixels, GL_RGB : 0.73s, average: 0.36ms, 2111mb/s
    cpu -> gpu,...
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    Re: is there an early stencil test?

    Your best bet is to use GL_EQUAL and disable stencil updates. I've seen speed improvements of some form or another from this all the way back to the 9800 Pro... though it may be even more effective...
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