[SDL] Game event loop and input

[Scott Harper]

> The first or second article in `Game Programming Gems 3' is about a
> similar topic to this.  He talks about a thing which he calls a Game
> Framework.  It has a website - www.gameframework.com - which is  
> updated
> reasonably regularly.

This website doesn't show up for me as anything other than a  
placeholder website owned by a company wanting to sell it.

> The basic concept is that you have `layers' which can each have  
> control.
> The layers are, well, `layered' on top of one another.  The top one  
> gets
> the first shot at the input, and if it doesn't handle it, the next one
> gets a go, and so on.  (There can be exclusive layers which don't give
> anyone else a go at the input.)  So the input cascades down the  
> chain of
> layers.  A menu can be an exclusive layer which tacks onto the front  
> of
> the stack.  You can have different layers for different parts of the
> interface.  It's quite flexible, and works pretty well with SDL.

You probably can do something like this pretty easily without having  
to resort to objects, but I've created a GameState class which I  
create subclasses of for each game state (menus, intro videos, loading  
screens, gameplay, etc...), and I maintain a stack structure of game  
states, pushing and popping when necessary for new game states.  So in  
my render and process threads I just peek at the stack and run that  
object's process/render methods each time through the loop, and if at  
some point the GameState object at the top of the stack doesn't return  
'true' to say 'rendered/processed normally', then I presume it's done  
with whatever it wanted or was doing, and I pop the stack and start  
working on the next lowest.

So what I came up with is kind of similar, I guess. ^_^  I'm not sure  
why or if the layers idea would be better, but either could be easily  
done in SDL (on-topic!) and work rather nicely, I think.

-- Scott