[Public WebGL] Some WebGL draft feedback

Gregg Tavares [email protected]
Tue Jan 5 11:46:57 PST 2010


On Tue, Jan 5, 2010 at 10:12 AM, Chris Marrin <[email protected]> wrote:

>
> On Jan 4, 2010, at 10:20 PM, Gregg Tavares wrote:
>
> >
> >
> > On Mon, Jan 4, 2010 at 9:21 PM, Mark Callow <[email protected]>
> wrote:
> > Gregg Tavares wrote:
> >
> > ... [snip] ...
> >
> > I don't follow the logic here? Which OS doesn't allow someone to use any
> API they want to draw to a window? Which system doesn't allow you to use any
> code you want to draw to a rectangle of pixels? Maybe I'm reading something
> into it but it seems like allowing multiple contexts as the normal thing to
> do and not allowing multiple contexts is only being advocated because it's
> hard for WebGL which doesn't seem like it should be the deciding factor.
> Rather then limit the usefulness of canvas by making it not allowed to have
> multiple contexts because of WebGL, if WebGL can't share then it doesn't
> belong in canvas.
> > ... [snip] ...
> > Sure you can use any API you want to draw to a window. If you start using
> multiple APIs for simultaneous drawing to the same window, which is what you
> are requesting here, it is entirely conceivable that the OS may not support
> it. When supported, at a minimum the application has to take responsibility
> for finding a suitable pixel format and synchronizing the drawing of those
> different APIs.
> >
> > What I am proposing is that the the only meaningful definition of the
> canvas tag is "a rectangle of pixels that allows multiple simultaneous APIs
> to effect those pixels" because as I pointed out, without multiple
> simultaneous contexts the canvas tag provides nothing that <object> or a
> specific <canvas2d> tag would not have supplied.
>
> You're speaking in absolutes, which is not useful to the discussion. I have
> never seen your definition and "multiple simultaneous APIs" is certainly
> arguable. Leave out the word "simultaneous" and you have a working
> definition that we can all agree on.
>
> It's a fact that the Canvas element was designed to work with more than one
> API, given the string passed to getContext. But what happens to a previously
> "gotten" context when you call getContext with a different string has never
> been defined. That is our job here. And I can tell you now with "absolute"
> certainty that adding the one word "simultaneous" to the spec would take it
> from something that has (depending on how you count) 3-6 working and mostly
> interoperable implementations, to something that would be difficult to
> implement on all platforms and impossible on some.
>


I'm saying it that way because without "simultaneous" contexts, the canvas
tag has no meaning. Without "simultaneous" contexts separate tags for each
API would have a better solution.

<2ddrawingservicewithcanvasapi>

and

<webgltag>

and

<logoliketag>

All solve the same problem. Making them work through

<canvas>

getContext("2d")
getContext("webgl")
getContext("logo")

adds no value if they can't be simultaneous. I don't understand why you fail
to see what I'm getting at nor have you acknowledged or responded to the
advantages of making webgl its own tag.










>
> -----
> ~Chris
> [email protected]
>
>
>
>
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