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Type: Posts; User: mbentrup

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  1. You shouldn't use glBufferSubData to update...

    You shouldn't use glBufferSubData to update individual fields in your UBO, create a structure in memory that matches your UBO layout and then upload it with a single call per frame.
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    Your calculation is correct: the GTX570M uses the...

    Your calculation is correct: the GTX570M uses the GF114 architecture, which has 48 cores per SM, while the GF110 (the original Fermi architecture) has only 32 cores per SM.
  3. Most DX10+ GPUs have mutliple processing units,...

    Most DX10+ GPUs have mutliple processing units, thus the draw batches are split into smaller batches and each is processed on a different unit. There is caching/sharing of vertices within a...
  4. This answer cannot be answered, because there is...

    This answer cannot be answered, because there is no simple FIFO post T&L cache in modern desktop GPUs. A FIFO cache is inherently serial, GPUs like to work in parallell, so you can't say the size of...
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    It's not just deprecated,...

    It's not just deprecated, glGetString(GL_EXTENSIONS) is not available in core profiles, you have to use glGetStringi().
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    If Khronos defines a generic assembly language,...

    If Khronos defines a generic assembly language, should there also be a strict GLSL to assembly mapping in the spec, or should every vendor be able to adjust his GLSL to assembly compiler to produce...
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    So, suppose the generic shader optimizer finds an...

    So, suppose the generic shader optimizer finds an opportunity to eliminate a common subexpression by storing it in a temporary register for later use. How should it decide if the cost of the...
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    Doesn't Nvidia convert all GLSL to ARB assembly,...

    Doesn't Nvidia convert all GLSL to ARB assembly, i.e. vectorized code, anyway ?
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    For a vertex cache of size 2 or more there will...

    For a vertex cache of size 2 or more there will be only 4 invocations for indexed triangles either.

    The gain in index buffer size is only relevant if you actually build long strips, but in that...
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    IMHO optimizing the generic shader code (except...

    IMHO optimizing the generic shader code (except for size maybe) is a bad idea, because a GPU vendor will do a HW-specific optimization of the code anyway. If the generic optimizer decides to unroll a...
  11. No driver vendor has to support the compatibility...

    No driver vendor has to support the compatibility profile, it is optional. So blame the driver vendors that they don't want to drop the functions that you don't need.

    I think, if Khronos stopped...
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    If there is a 3 frame delay between command...

    If there is a 3 frame delay between command submission and execution, it makes sense that you get the delay twice, because when you submit the ReadBufferData command in frame 3, there are two more...
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    Generally you cannot request an OpenGL context of...

    Generally you cannot request an OpenGL context of a specific version. The GLW API, which is the link between OpenGL and the Windows system allows the application to specify an OpenGL version, but it...
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    If you have samples per Pixel, the OpenGL may...

    If you have <n> samples per Pixel, the OpenGL may run the fragment shader any number between 1 and <n> times per fragment. If the number of fragment shader invocations is less than the number of...
  15. Another issue may be that you have automatic...

    Another issue may be that you have automatic mipmap generation enabled, that would require decompress/downscale/recompress to next lower level steps for the compressed format, while uncompressed...
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    You should set stencil to 1 instead of increment...

    You should set stencil to 1 instead of increment in step 1.1.3, otherwise it would fail if the shape overlaps itself.
  17. Clipping a triangle by a sphere will not give you...

    Clipping a triangle by a sphere will not give you another triangle (or two) as clipping it with a plane does. You could instead use a fragment shader to discard all fragments outside the clipping...
  18. When you request version 3.0 you will get a...

    When you request version 3.0 you will get a compatibility context (well, technichally there are no profiles before version 3.2, but the contexts <= 3.1 behave exactly like compatibilty contexts),...
  19. The texture proxy will *not* tell you if there's...

    The texture proxy will *not* tell you if there's enough memory to allocate a texture of that size, it checks only that the driver is generally capable of working with a texture of the given size and...
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    The post-VS cache in modern GPUs is not a strict...

    The post-VS cache in modern GPUs is not a strict FIFO, because the vertices are processed in parallel. I think AMD GPUs process up to 64 vertices at the same time and NVidia 32. However, the FIFO...
  21. Look here:...

    Look here: http://www.opengl.org/sdk/docs/manglsl/xhtml/textureSize.xml
  22. This is addressed in issue #10 of...

    This is addressed in issue #10 of http://www.opengl.org/registry/specs/ARB/texture_view.txt. You have to be careful because a compressed texture and a matching integer texture will have different...
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    The difference is that you draw all the QUADS in...

    The difference is that you draw all the QUADS in one batch (one glBegin/glEnd pair), while the VBO version makes a draw call for every two triangles. Try to make one index buffer containing 20000...
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    The shader objects are needed only for linking...

    The shader objects are needed only for linking the program, you can delete them after you linked the program.
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    Unless you have a driver supporting...

    Unless you have a driver supporting GL_ARB_shader_stencil_export there's no easy way to do that. When I needed a certain pattern in the stencil buffer for stencil routing I ended up with an 8-pass...
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