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  1. Thanks for your reply. This makes sense. One...

    Thanks for your reply. This makes sense.


    One last question, if my shader has to perform multiple atomicMin's at the same memory location, but without ever having the need to read any old value...
  2. imageAtomicMin(), memoryBarrier() and coherent uniform qualifier

    Hi,

    I have a shader that pokes into a framebuffer-sized image (uimage2D) when rendering fragments.
    Eg. everytime a fragment shader invocation is run, the following happens:


    uniform uimage2D...
  3. Kepler GK110 - using atomicMin64 from GLSL?

    Hi,

    According to the following document (*), GK110 GPUs (eg. GTX 780) offer atomicMin/Max/And/Or/Xor operations on 64-bit unsigned integers.

    How can I access this functionality through GLSL? It...
  4. Unable to attach separate stencil buffer to FBO (packed depth+stencil is fine)

    Hi,

    I can use a packed depth stencil with my FBO just fine using the following code (color buffer construction code omitted):


    glBindTexture(target = GL_TEXTURE_2D, texture = 17)...
  5. It seems early stencil cull is completely...

    It seems early stencil cull is completely disabled as soon as discard is being used in the shader.
    I don't understand why, as the stencil test should be done before the depth test and rasterization....
  6. Can't manage to get early stencil culling to work...

    Can't manage to get early stencil culling to work :(

    From what I can see, nVidia has a patent on stencil-based culling, but how I can enable it?
    http://www.freepatentsonline.com/7184040.html

    I...
  7. Early fragment culling using the stencil buffe

    Hi,

    I have a fragment shader that writes to the depth buffer (gl_FragDepth) and does some pretty expensive work. This shader only needs to run on a few screen pixels (maybe a thousand or more)....
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    This makes sense. I tried with a regular...

    This makes sense.


    I tried with a regular GL_RGBA pixel format and get the following:

    1085

    So it's better, but it isn't perfect. I verified the values in the depth buffer and the missing...
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    Ouch. I believe you, but I am just very...

    Ouch. I believe you, but I am just very surprised. I thought that, say, one-pixel sized triangles would always get rendered as a single fragment, but according to what you say, very often, they won't...
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    Have a look at the following image: 1084 ...

    When a group of triangles cover a fragment, the fragment's centre will lie within one of the triangles, and thus be rendered. OpenGL's rasterisation rules require that, in this situation, the...
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    [/LIST] Does this mean most fragments don't...

    [/LIST]
    Does this mean most fragments don't actually get rendered in my situation?
    This rule makes sense but sounds a bit odd to me. Afterall, fragments at triangle endpoints usually do not lie in...
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    This is what I am surprised with. And I do render...

    This is what I am surprised with. And I do render every single fragment (gl_FragColor = vec4(1,0,0,1)).


    I don't have antialiasing enabled.
  13. Replies
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    Unexpected GPU triangle rasterization output

    Hi,

    I'm trying to render the geometry that is shown in the following screenshot (wireframe mode):

    1081

    This geometry is issued from dynamic tessellation, with fixed tessellation factors. As...
  14. Very weird spec... Also, in the code above...

    Very weird spec...

    Also, in the code above with the teapot, does it mean the driver doesn't do any form of Early-Z test when I'm not using layout(early_fragment_tests)?
    What about Early-Z/Hyper-Z...
  15. early_fragment_tests doesn't work with discard,...

    early_fragment_tests doesn't work with discard, period.

    With early_fragment_tests disabled:

    1061

    And now with early_fragment_tests enabled:

    1062
  16. Given that all threads always branch the same...

    Given that all threads always branch the same way, how come the GPU tries to execute both branches?

    You know what... don't feel obliged to answer here ;) I am on the brink of drawing the...
  17. Same result with the latest 320.18 drivers. ...

    Same result with the latest 320.18 drivers.

    I'm using FBO attachments, COLOR0 + DEPTH. Surely early_fragment_tests works correctly with these in place, I don't see any reason why it wouldn't?
  18. I am not using atomics or image stores or loads...

    I am not using atomics or image stores or loads in this shader, it is just a plain raster-or-discard routine.

    I see that the problem happens only when discard has been called. Fragments that are...
  19. How? My isBound uniform value is invariably 0,...

    How? My isBound uniform value is invariably 0, under all circumstances. No thread is trying to access the wrong branch.


    *Which ones*? What are these threads you are talking about? Again, my...
  20. gl_FragDeph not written to, but unexpected layout(early_fragment_tests) behavior

    Hi,

    My program behaves differently with and without layout(early_fragment_tests) in my fragment shader.
    My fragment shader either writes out a pixel or discards, but I'm not writing to...
  21. I didn't get it twisted. My problem came from the...

    I didn't get it twisted. My problem came from the samplers not being bound, regardless of whether I was using dynamically evaluted uniforms or something else (I was indeed using a dynamically...
  22. You are right, shader subroutines are a more...

    You are right, shader subroutines are a more appropriate way of instructing the driver which block of code is or is not used at runtime, and therefore the driver might not complain about unbound...
  23. Thanks for your reply. For the stuff I am...

    Thanks for your reply.
    For the stuff I am interested in, I think I'm running into the general limitation of atomics for this problem. Basically, I would like to read a couple of uints (or vec4's,...
  24. I can't find anywhere on the web a paragraph that...

    I can't find anywhere on the web a paragraph that says that shader samplers MUST be bound.

    EDIT: I only found your post here:...
  25. Ok on that part. int or vec3, who cares, they're...

    Ok on that part. int or vec3, who cares, they're both uniform values. Fine.



    GPUs do not have a branch prediction unit, do they? Therefore they don't speculatively execute the code of the wrong...
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