[Public WebGL] Some WebGL draft feedback

Mark Callow [email protected]
Tue Jan 12 18:29:09 PST 2010

Hi Ken,

Without explicit wait calls, every rendering call of every API needs to 
a test to check if some other context is currently rendering and if so, 
wait for it. This test will affect performance. It might only be a 
single if, but it will be in every rendering call. It also means that 
each rendering API needs to know about all the other APIs that can be 
used, which in turn means you have to update every API when a new one is 

And then there is Chris's point, that hiding the synchronization, makes 
people not realize the impact of their simple change to, e.g., draw a 
score on their WebGL game using a 2D API.

Having explicit sync. makes it clear to everyone what is going on and 
keeps the APIs independent of each other.



Kenneth Russell wrote:
>     All this is why I think our best way forward is (a) for
>     getContext() to return null when trying to create a second
>     rendering API on implementations that do not support simultaneous
>     rendering, and (b) to have explicit sync point calls
>     (waitContext("xxx") as Mark proposes, or similar) for
>     implementations that do. I believe this gives support for
>     simultaneous rendering without the burden of mandating its
>     support. It also allows more flexibility in how simultaneous
>     rendering is implemented.
> Agree on point (a). I don't think the explicit wait calls need to be 
> or should be exposed to JavaScript, though. They can be called under 
> the hood when the developer starts rendering with a different context. 
> How would exposing them provide more flexibility to implementations?
> -Ken
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