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Re: [Public WebGL] Please review WebGL multiple render target extension proposal



Yes.


On Wed, Oct 17, 2012 at 11:25 AM, Florian Bösch <pyalot@gmail.com> wrote:
> Right, so the idea's to introduce FP-textures properly a second time around
> which would modify the framebuffer/mrt extensions clamping behavior?
>
>
> On Wed, Oct 17, 2012 at 8:14 PM, Kenneth Russell <kbr@google.com> wrote:
>>
>> Ah, sorry, pulled the trigger too quickly on that email. I see the
>> section you're pointing out.
>>
>> It's been pointed out most vehemently by Mark Callow that I in
>> particular glossed over the subtleties of floating-point render
>> targets when adding optional support for them in the WebGL exposure of
>> OES_texture_float. There is an ongoing discussion about the
>> correctness of the OES_texture_float conformance test as well
>> (http://www.khronos.org/bugzilla/show_bug.cgi?id=729).
>>
>> Another OpenGL ES extension proposal should be coming soon which
>> supports floating-point render targets more thoroughly than WebGL's
>> exposure of OES_texture_float, and I think that rather than try to
>> patch up the existing specs we should just wait for that one to come
>> along and then point to it. From the standpoint of the MRT extension,
>> OES_texture_float should be considered to affect individual color
>> attachments in the same way that it affects the previous single color
>> attachment to FBOs. I wouldn't want to do a half-baked job again
>> trying to add FP render target support to this MRT extension so again
>> let's wait for the new extension.
>>
>> The vast majority of ES 2.0 hardware will not support floating-point
>> render targets, but my hope is that some or most ES 3.0 hardware will.
>>
>> -Ken
>>
>>
>> On Wed, Oct 17, 2012 at 11:04 AM, Kenneth Russell <kbr@google.com> wrote:
>> > This is pretty much an orthogonal question to the MRT proposal. Please
>> > start a new thread for it.
>> >
>> > -Ken
>> >
>> >
>> > On Wed, Oct 17, 2012 at 2:11 AM, Florian Bösch <pyalot@gmail.com> wrote:
>> >> I think that's fine. I've got one question though. I know that when I
>> >> attach
>> >> a floating point texture, that the output values are not clamped to
>> >> 0-1. I
>> >> also know that the OpenGL ES 2.0 specification states the clamping as
>> >> behavior (which is also mentioned in this extension). I'm not sure, but
>> >> I
>> >> think the desktop versions of OpenGL don't specify the clamping at the
>> >> shader output level (there's some function to control clamping).
>> >>
>> >> I'm a bit worried that this might be a behavioral difference between
>> >> Mobiles/Desktops that could shoot you in the foot if/when you find a
>> >> mobile
>> >> with floating point texture render target support. Anybody know if
>> >> mobiles
>> >> do the clamping regardless of target format?
>> >>
>> >> On Wed, Oct 17, 2012 at 3:51 AM, Kenneth Russell <kbr@google.com>
>> >> wrote:
>> >>>
>> >>>
>> >>> Please review an extension proposal adding multiple render target
>> >>> functionality to WebGL:
>> >>>
>> >>>
>> >>>
>> >>> http://www.khronos.org/registry/webgl/extensions/proposals/WEBGL_multiple_render_targets/
>> >>>
>> >>> It mirrors a proposed extension for ANGLE which adds this
>> >>> functionality to OpenGL ES 2.0:
>> >>>
>> >>>
>> >>>
>> >>> https://angleproject.googlecode.com/svn/trunk/extensions/ANGLE_multiple_render_targets.txt
>> >>>
>> >>> Please provide your feedback on both.
>> >>>
>> >>> Apologies for how long it took to produce these extensions. They
>> >>> couldn't be drafted until OpenGL ES 3.0 was released, because in order
>> >>> to avoid compatibility issues in the future, it was necessary to
>> >>> derive their contents from the ES 3.0 specification. The draft ANGLE
>> >>> extension modifies the same areas of the OpenGL ES 2.0 specification
>> >>> modified by the GL_NV_fbo_color_attachments and GL_NV_draw_buffers
>> >>> extensions, but draws the majority of its text and semantics from the
>> >>> ES 3.0 spec.
>> >>>
>> >>> -Ken
>> >>>
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>> >>>
>> >>
>
>

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