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Re: [Public WebGL] Some WebGL draft feedback



On Mon, Jan 11, 2010 at 10:12 PM, Mark Callow <callow_mark@hicorp.co.jp> wrote:
Kenneth Russell wrote:
On Fri, Jan 8, 2010 at 2:54 PM, Chris Marrin <cmarrin@apple.com> wrote:

The ability to support 2 separate OpenGL contexts on the same drawable is certainly not a universal feature. We shouldn't its existence on a particular platform as evidence that it would be easy to support on any platform. It's important for the design to be adaptable to many architectures without unduly hampering some.

It's a feature in every OpenGL window system binding I'm aware of except those on Mac OS X, which doesn't provide an abstraction for the OpenGL drawable.
It is not a "feature" of every OpenGL ES 1.1 window system binding. I put feature in quotes because the feature is supported by the EGL API but implementations are not required to support EGL surfaces that can be rendered to by multiple contexts. I have not yet worked with enough ES 2.0 implementations to be able to make the same statement for that but I would not be in the least surprised to find similarly limited implementations.

I see the text you're referring to: section 3.7, footnote 9 of the EGL 1.4 specification. That's awful.

My basic point stands, though, which is that the API supports it. Mac OS X has no notion of an OpenGL drawable in the public API and it is the only OpenGL window system binding with this characteristic.

-Ken