[Public WebGL] Some WebGL draft feedback

Kenneth Russell [email protected]
Fri Jan 8 13:58:07 PST 2010

I have also worked on interoperability issues with Java 2D, specifically
with the Java bindings to OpenGL. A few years ago an OpenGL backend for Java
2D was developed, and we were able to cleanly integrate the two APIs by
creating two OpenGL contexts against the same drawable. A browser vendor
desiring hardware acceleration for all of their Canvas contexts could use
the same technique.

For certain operations, like overlaying text on 3D output, it's much simpler
to use a 2D API than to convert everything to OpenGL.

Another interoperability mechanism, which already exists in both the 2D and
WebGL contexts, is to allow a Canvas to be used as input to the API. We
should consider whether all Canvas context APIs should be required to take a
Canvas as input. We should also consider whether it's a good idea, even if
this capability is present, to mandate that Canvas may not support multiple
simultaneous rendering contexts.


On Thu, Jan 7, 2010 at 6:36 PM, Mark Callow <[email protected]>wrote:

> I completely agree with Vlad. I have been dealing with the issues of mixing
> Java2D rendering and M3G rendering on the same Java Canvas for some time
> now. It really does complicate the implementation and brings little benefit,
> especially when you have shaders. Most of the fancy pixel twiddling done by
> the sequence of APIs Greg used as an example can be achieved in WebGL with
> shaders and framebuffer objects.
> Regards
>   -Mark
> Vladimir Vukicevic wrote:
>> I still don't like having multiple contexts on <canvas> at all, even with
>> explicit sync points.  It complicates implementation for not much benefit,
>> given that the implementation will almost certainly have to do something
>> similar to what the user would already be able to do (copy the framebuffer
>> contents around), but with added complexity -- having to keep the GL context
>> and all associated objects around, for example.
>>    - Vlad
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