Re: [boost] [flyweight] key value with objects not constructible from a key

Subject: Re: [boost] [flyweight] key value with objects not constructible from a key
From: Michael Marcin (mike.marcin_at_[hidden])
Date: 2008-11-13 12:23:08

Mathias Gaunard wrote:
> Michael Marcin wrote:
> 
>> When loading a texture in OpenGL the texture is bound to the current 
>> OpenGL context which is stored per thread. OpenGL textures must be 
>> destroyed and recreated when you change resolution because you must 
>> also destroy and recreate your OpenGL context. A thread can have 
>> multiple contexts but only 1 may be current at time. The collection of 
>> textures, which flyweight stores in its factory, is logically bound to 
>> the current render context on the current thread.
> 
> So you need a per-context factory.
> Boost.Flyweight factories are global by design, the way I see them. So 
> it's not ideal for what you want.
> You can get around this by putting the context in the key, however.
> 

With the way OpenGL works only one context can be active at a time per 
thread. By using a custom hold I think I can change the active factory 
when I changed the active context.

I need to think about the factory in the key thing more though.