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Thread: OpenGL 3 Updates

  1. #101
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    Re: OpenGL 3 Updates

    it simply narrows the search for a valid format.
    That makes sense, but only when you're looking at a format in a vacuum. When you look at it as a tool for solving a problem, for fulfilling a need, it doesn't make as much sense.

    If you have a need for a floating-point image, a fixed-point one will not work. That's why you decided you needed a floating-point one. If you need a 4-channel render target, an unrenderable format will not work. And so on.

    Which means that, in the event of failing to create the preferred format, the number of usable alternatives is quite small. Indeed, it is something that you want to have explicit control over, not start blindly enumerating all possible formats. Most important of all, what makes the format usable is the intended use, which generally cannot be boiled down to an enumeration. So if you really need a 2048x2048x128fp format that supports being a render target, supports blending, and supports filtering, your method would be useless, because it would return a format that fills only some of those requirements.

    Your pseudo-code is broken in precisely this way: it is ignorant of need.

    If your code needs feature X, not getting it should mean a hard break. It should not mean, "Keep trying until you return something". It should stop, return an error, throw an exception, anything but return something valid.

  2. #102
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    Re: OpenGL 3 Updates

    ^I don't see how that's any different in terms of complexity. In order to significantly reduce it that way, you'd have to assume that a given feature is "always available" or "always missing". That simply isn't the case when you've got things like blending available for float16s but not float32s.

    A better option would be to use format objects, but allow them to be specified incrementally, so that the addition of one particular aspect can be detected as the point of failure. In fact, a means could even be devised to suggest other values for existing features which *would* allow the failed feature to be supported. This latter part would necessarily be limited, and perhaps need to be user-requested (since the programmer would have a good idea what they'd be willing to compromise on).

    Granted, this does somewhat break the "object won't exist at all if it isn't complete" notion, but ways around that could be devised. Perhaps put the above functionality in a factory class that only outputs a finished format object when it has a complete set of valid features?

  3. #103
    Senior Member OpenGL Guru knackered's Avatar
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    Re: OpenGL 3 Updates

    bang goes any chance of getting any feedback from the original poster on any of these questions. As usual it's descended into an 11 page dick waving contest.
    Knackered

  4. #104
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    Re: OpenGL 3 Updates

    As usual it's descended into an 11 page dick waving contest.
    Right. Because it's not a discussion of the features you care about.

  5. #105
    Senior Member OpenGL Guru knackered's Avatar
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    Re: OpenGL 3 Updates

    It's not the subject matter I resent, it's the protagonists. I wanted to hear something from the horses mouth while for one split second we had his attention. Carry on, it's too late now.
    Knackered

  6. #106
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    Re: OpenGL 3 Updates

    Sorry for fanning the flames before, I just find it completely ridiculous that D3D10 is approaching 2 years, and there's not even a working alpha version of OpenGL 3.0. And seeing it not learning the lessons of D3D10 (cutting old junk like alpha test, specifying a reasonable minimum level of functionality) makes it even worse. I know that the goals are different, but why is Microsoft so much more efficient at defining standards? It doesn't make sense.

    I hope I don't start another flame thread with this

  7. #107
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    Re: OpenGL 3 Updates

    Microsoft doesn't define standards. They just write code that everyone conforms to despite its non-standard-ness.

  8. #108
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    Re: OpenGL 3 Updates

    What i most want to see in Pipeline 005 is a discussion on how best to set-up a multi-threaded application for OpenGL 3.

    eg. Say that i want to generate a shadow map and do a z-only pass from the camera view, two completely separate operations except that they share a vertex buffer.

    Is it most efficient to:
    1. Have two separate threads with separate rendering contexts perform both operations simultaniously.
    2. Have one thread do the shadow map, then switch rendering contexts and do the z-pass afterwards.
    3. Have one thread and one rendering context and attach different objects to it when we switch to the z-pass.

  9. #109
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    Re: OpenGL 3 Updates

    Quote Originally Posted by Lindley
    Microsoft doesn't define standards. They just write code that everyone conforms to despite its non-standard-ness.
    What's worth more? A solid de-facto standard with working implementations, or a perfect formal academic standard with no implementations?

  10. #110
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    Re: OpenGL 3 Updates

    I just find it completely ridiculous that D3D10 is approaching 2 years, and there's not even a working alpha version of OpenGL 3.0.
    Um, why does that surprise you in any way? The effort to create GL 3.0 didn't even start until almost 2 years ago.

    Further, D3D 10 did not exist before Vista. Oh, it was some nice paper, but it wasn't a real thing until developers could actually use it. So the 2 year timeline itself is stretching things.

    specifying a reasonable minimum level of functionality
    Um, did you read the original post? It does specify a minimum level of functionality. Just not one that says, "Only G80 and R600 cards may apply." Because that would be incredibly stupid. For obvious reasons.

    And Microsoft (and software developers) are encountering some of those obvious reasons right now.

    why is Microsoft so much more efficient at defining standards?
    Because Microsoft is one entity. It doesn't take long for one entity to agree to something. The more people you get making the decision, the more likely you are to make the right one (to a degree), but the longer it will take.

    1. Have two separate threads with separate rendering contexts perform both operations simultaniously.
    Unless you're on a multi-GPU system (and they specifically allow for it), I can guarantee that this is a bad idea. And by bad, I mean "probably non-functional". One GPU means one renderer, no matter how many contexts or CPU threads you create.

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