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  1. I don't really understand what you mean by empty,...

    I don't really understand what you mean by empty, a region of constant color ?

    However, all TC formats have a fixed compression ratio, the compressed size of an "empty" texture is exactly the same...
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    By the way, you seem to use a float uniform where...

    By the way, you seem to use a float uniform where a bool uniform would be more appropriate. If the driver knows that there are only 2 possible input values it can compile two shader variants to avoid...
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    Well, actually the trend in graphics APIs (Metal,...

    Well, actually the trend in graphics APIs (Metal, DX12, glNext) is to go away from abstraction, closer to the hardware.
  4. If you don't have ARB_shader_stencil_export, you...

    If you don't have ARB_shader_stencil_export, you can still write a specific value to the stencil buffer in ceil(log2(N)) passes, if you write one bit of the stencil per pass. However, I'd just use a...
  5. I think every driver keeps a flag per texture...

    I think every driver keeps a flag per texture that is set on validation and reset on modification, so that further validations are not done until the texture is changed.
  6. On old GPUs the FP implementation is not always...

    On old GPUs the FP implementation is not always IEEE compliant, but as far as i know that non-compliance is mostly in areas like NaNs and denormal number handling. You can assume that the floats have...
  7. Sticky: EGL ? It already has the means to load various...

    EGL ? It already has the means to load various APIs and I guess vendors shipping EGL for their products will have to work on a common EGL ABI for Windows anyway.
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    ASTC can encode one- and two-channel images, but...

    ASTC can encode one- and two-channel images, but you have to encode them as luminance resp. luminance+alpha and the HDR range is basically FP16, I think that is the same range as BPTC.
  9. The first thing I'd do would be to look into the...

    The first thing I'd do would be to look into the KHR_debug output, Nvidia may give some hints if the shader hits a slow path.
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    Small nitpick: vertex attributes are not...

    Small nitpick: vertex attributes are not flat-shaded, only varyings can be flat-shaded.

    Another way to implement clipping of primitives is to use (drumroll) vertex clipping. Just write the four...
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    In practice OpenGL 3.0 added very little new...

    In practice OpenGL 3.0 added very little new functionality over 2.1, because a lot of it was already available as common extensions to 2.1 (framebuffer object, floating point textures etc.), and...
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    The changes of OpenGL 3.3 and later versions have...

    The changes of OpenGL 3.3 and later versions have been released separately as ARB extensions too, so restricting the GL version wouldn't necessarily disable any features.
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    Hi Alfonse, the 4.5 core spec says in A.5 ...

    Hi Alfonse,

    the 4.5 core spec says in A.5 with corrolary

    This indicates that there is a distinction between the vertex as identified by vertex ID, etc. and vertex shader invocation. There may...
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    MESA does it, though their stub segfaults instead...

    MESA does it, though their stub segfaults instead of returning an OpenGL error: http://cgit.freedesktop.org/mesa/mesa/tree/src/mapi/glapi/glapi_getproc.c#n502

    This has been discussed extensively...
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    At least on Linux glXGetProcAddress() will never...

    At least on Linux glXGetProcAddress() will never return NULL. If the requested function is unknown to the GL driver, it will return a stub that just throws an error on every call.



    Returning...
  16. As a side-note: the DXT1 and DXT5 formats are not...

    As a side-note: the DXT1 and DXT5 formats are not part of OpenGL, as they are covered by patents. But they are implemented in hardware on all desktop GPUs. On the other hand the ETC/EAC format is...
  17. On Desktop OpenGL you can basically only use the...

    On Desktop OpenGL you can basically only use the DXT variants or the BPTC format if you can assume DX10 or higher hardware. The ETC format is required by the OpenGL spec, but it is in fact not...
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    OpenGL 4.3 is a subset of OpenGL 4.5, so both...

    OpenGL 4.3 is a subset of OpenGL 4.5, so both cards support all OpenGL 4.3 functions. Support for a newer OpenGL version in the driver should not matter at all.

    However, different hardware/drivers...
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    As you have to map the buffer anyway to read the...

    As you have to map the buffer anyway to read the counter, can't you just reset it in the same step ?


    Well, if the atomic counter is allocated on the CPU, the atomicIncrement has to access it...
  20. Actually you can only request a context that is...

    Actually you can only request a context that is backward compatible to the specified version, but you cannot prevent the driver from creating a higher version.

    Even if you could request a version...
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    attribute short vertexIndex; There is no...

    attribute short vertexIndex;



    There is no type "short" in GLSL. Use "int".
  22. OpenGL versions are mostly upwards compatible and...

    OpenGL versions are mostly upwards compatible and practically all new features are available as extensions, so you could use e.g. tesselation shaders, persistent buffer mappings and shader storage...
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    NVidia (and as far as I know most other vendors)...

    NVidia (and as far as I know most other vendors) recompiles shaders automatically depending on GL settings. It even issues a performance warning to the debug log when it does this.

    However, this...
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    The advantage of dual quaternions is that they...

    The advantage of dual quaternions is that they can be composed easily, the algebra just works.

    If you use a quaternion + vector representation, you basically decompose your transform into a...
  25. I wonder who is the intended target for this...

    I wonder who is the intended target for this DSA-only GL. Khronos already works on OpenGLng, which is presumably an entirely different API, with much lower driver overhead, less "cruft" and (I guess)...
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