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Thread: Official feedback on OpenGL 4.3 thread

  1. #91
    Intern Contributor
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    Jul 2010
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    74
    Will GL_EXT_depth_bounds_test be promoted to core now that both AMD and NVidia support it?

  2. #92
    Junior Member Regular Contributor
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    Dec 2009
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    198
    The OpenGL 4.3 core spec removed the GL_ALPHA format for glReadPixels (chapter 18.2.1, page 458). The other single-component formats GL_RED, GL_GREEN and GL_BLUE are supported, but GL_ALPHA is only supported in the compatibility profile. In 4.2 core all 4 individual components could be read with glReadPixels.

    Is there a reason why the alpha channel is treated special here ?

  3. #93
    Intern Contributor
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    Mar 2010
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    Winston-Salem, NC
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    Quote Originally Posted by absence View Post
    Correct, and in order to decide whether to use a feature or not it needs to exist.
    It also needs to be used by a lot of people. If very few people actually use a feature, then it usually has very little testing or IHV support. Anything "not on the common paths" is very likely to blow up or not provide any benefits, just due to the exponential branching complexity of oh-so-many features. Ideally, any proposed feature would have some kind of "preliminary consensus" that it can indeed be a benefit, and would indeed match a lot of people's expected case uses.

  4. #94
    Junior Member Newbie
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    Mar 2013
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    20
    The nonsensical description of DrawElements was eventually fixed in 4.3 spec, nice! However, it would be good if the
    description of the "indices" parameters would reflect the according meaning on the ref pages as well (of it being an offset,
    not any sort of pointer C-type).

  5. #95
    Junior Member Regular Contributor
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    Jan 2004
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    Czech Republic, EU
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    190
    Quote Originally Posted by Brandon J. Van Every View Post
    It also needs to be used by a lot of people. If very few people actually use a feature, then it usually has very little testing or IHV support. Anything "not on the common paths" is very likely to blow up or not provide any benefits, just due to the exponential branching complexity of oh-so-many features. Ideally, any proposed feature would have some kind of "preliminary consensus" that it can indeed be a benefit, and would indeed match a lot of people's expected case uses.
    This is mostly incorrect. Features are (or should be) tested before they are released regardless of popularity of each feature, and the way to achieve that is to write tests or use an existing test suite which can assess the quality of an OpenGL implementation. There is the official OpenGL conformance test suite developed by Khronos that driver developers should use first. There is also Piglit, the unofficial open source OpenGL test suite, which is pretty huge and it's getting bigger every day with 89 contributors so far. Finally, driver developers should write their own tests for features they implement (I know major vendors do that, though the specification coverage of their tests might vary a lot, considering AMD passed about 75 % of Piglit tests last time I checked, which is not very good, and NVIDIA even less than that).
    (usually just hobbyist) OpenGL driver developer

  6. #96
    Senior Member OpenGL Guru
    Join Date
    May 2009
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    4,948
    This is mostly incorrect. Features are (or should be) tested before they are released regardless of popularity of each feature, and the way to achieve that is to write tests or use an existing test suite which can assess the quality of an OpenGL implementation.
    You seem very conflicted about what you're saying.

    On the one hand, you're saying that the post is wrong to say that only some features are being tested. Yet you cite low Piglit scores and the obvious lack of comprehensive testing by driver developers. So clearly some features are not being properly tested. So you agree with Brandon's point: that staying on commonly tread ground is the most effective way to avoid driver bugs.

    The post you're responding to is not talking about what "should be"; the post is talking about what is currently. And you seem to agree with his explanation of the current state of things.

    So what is "mostly incorrect" about what he's saying?

    There is the official OpenGL conformance test suite developed by Khronos that driver developers should use first.
    If there is a desktop OpenGL conformance test, I haven't heard of it. The old conformance test for desktop GL was never updated; it never even checked conformance to 2.0. So it's worthless for anything more recent. OpenGL ES 2.0 and 3.0 have conformance tests, but not desktop GL.

    Khronos said that they were interested in making one, but they haven't announced anything beyond interest.

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