Re: Resizing contexts

[Frank C <li...@si...>]

On 6-Aug-04, at 10:41 PM, James W. Walker wrote:

> On Aug 6, 2004, at 4:17 PM, Frank C wrote:
>
>> It appears Quesa rebuilds the GL context whenever it's resized, which 
>> can take a good _long_ while if you have a lot of textures loaded 
>> (pretty much rules out using live-resize windows on OS X). Would it 
>> be reasonable to have a GLDrawContext_UpdateSize function to avoid 
>> rebuilding textures for a resize event? I'm fairly certain all you 
>> have to do is update the viewport and clipping rect - trashing the 
>> context isn't needed or desirable.
>>
>> Comments?
>
> On the Mac, you would also need to call aglUpdateContext, i think.

That would be part of updating the clipping rect. On Mac OS, you would 
have to grab the context port dimensions, update AGL_BUFFER_RECT, 
update glViewport, and finally call aglUpdateContext. The first two 
steps can be ignored for offscreen contexts.

> I do not see any analogous wgl call for Windows.  I don't know if that 
> means that the wgl layer does not need to be informed of a window 
> resize, or if it means that you must recreate the context.

Ya, it looks like GLDrawContext_UpdateWindowClip does nothing on 
platforms other than Mac OS so perhaps updates are automatic, but I 
can't offer any more insight. glViewport would certainly need to be 
updated in all cases however.

I hacked in support for the Mac at this point and it's a whole lot 
nicer when using freely resizable windows, but I ran into a bit of 
roadblock in IRRenderer_StartFrame. It seems the context flags get 
trashed before getting there when a resize is pending (forcing a 
rebuild), but I can't see where that happens. I traced one such case to 
e3drawcontext_mac_update but it still occurs after modifying that 
function. I'll look at it some more over the weekend...

Thanks,
Frank.