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Re: [Public WebGL] The Newly Expanded Color Space Issue



On Sep 7, 2010, at 11:14 AM, Steve Baker wrote:

> Chris Marrin wrote:
>> On Sep 7, 2010, at 10:19 AM, Steve Baker wrote:
>> 
>> 
>>> I think we have to take this one teeny-tiny step at a time.   First, let
>>> us establish once and for all what color space GLSL shaders operate in.
>>> 
>> 
>> Let me give a much simpler answer than I think you're looking for. I can say with complete and utter certitude that a GLSL shader can operate in any color space it chooses to operate in. I could make my shader work in a CIE 1976 (L*, a*, b*) color space if I so chose. And as long as I did the appropriate conversions on output, everything would would be correct to within the precision limits of the system. It might be exceedingly difficult, and maybe even impossible to do with complete mathematical accuracy. But it is the beauty of shaders that they allow you to do virtually anything.
>> 
> That's is PRECISELY why I want someone to answer those three questions
> rather than just shooting more long emails at each other.

Sorry to disappoint you. I have neither the expertise, nor the time to become a sufficient expert to give correct answers to your questions, if any such answers even exist. And those answers are not necessary to our conversation. Please read on.

> 
> So please - I beg of you - if you believe what you just wrote then
> please answer my three questions, simply and directly and with actual
> code examples.   I don't think you can do that...I don't think anyone
> can...and that means that I firmly believe that what you just wrote is
> 100% incorrect.   So - please, please, pretty-please-with-sugar-on-top,
> if you believe that what you just wrote is true - then you can easily
> answer my three simple, practical programming questions and thereby
> silence my complaints once and for all.

While this is a consensus driven process, the goal of this discussion is not to silence your complaints. We all have to accept that our opinions are just that. The most important goal is that we all agree that WebGL is a sufficient solution for a large number of problems. Threats of abandoning WebGL notwithstanding, that is the best we can do or we will never have a WebGL spec.

> 
> That's the only way this situation can be clearly resolved.

There's one thing I think it's important to make clear. There is no "situation" to be resolved here. If we made no changes at all WebGL would still be a very useful and powerful tool. What we are trying to do here is to make it possible for WebGL to be applicable to a wider range of problems. This conversation started because we believed it would be useful for authors to be able to ensure that images could get into texture memory unchanged. It's hopefully clear to all now the value of that feature and I hope to see it added to the spec soon.

In the course of that conversation it became clear that the color space used by the WebGL drawing buffer was not well defined. Furthermore there was controversy about what the "right" format for the drawing buffer is. It became clear that there was no "right" format, so I proposed we let the author choose between two obvious choices. I'm not sure how answering your math quiz changes that proposal. But others seem to think it is a reasonable compromise.

-----
~Chris
cmarrin@apple.com




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