[Bf-gamedev] Proposal: finer clock management

[Arnaud Degroote]

Hi, I want to propose some mechanisms to allow better clock management
at the Game Engine Level.

At the moment, there is globally two tick models, one 'real-time' with
possibly frame drop, and another one which basically 'render all frame'. 

What I would like to do is to be able to 'accelerate' game engine, (i.e.
make the world move faster than 'real-time'), or 'slow-down' the world
(bullet effect-like) or even 'pause' the world. 

To 'pause' the world, I can just use suspend(). For 'slow-down', you can
do it in some complex method, using suspend() at different intervals for
different scenes to get more or less the desired behaviour, but it seems
quite complex and costly. To accelerate the world, as far as I know,
there is no easy way to do it.

What I propose in these patches is to allow a 'user-settable' clock,
i.e. the possibility for the developer to finely control how the time
elapse in its game.

The next issue is how to call it. Calling it from a 'normal' logic block
is a bit dangerous as, if for any reason, you don't make the time
progress enough, there is good change that your logic brick won't be
called anymore. 

So, one safer possibility is to use the 'main python controller' (see
KX_GetPythonMain) but it may a bit overkill in lot of situation. Maybe
we can add another special property (such as __main__) (I think at a
__clock__ property), and call it automatically, if it exists in 
BL_KetsjiNextFrame.

I would like to have your opinions on my goal (maybe I miss some easier
way to achieve it), current attached patches, and proposal to continue. 

Thanks in advance. Best regards,

-- 
Arnaud Degroote
Postdoc
RIA LAAS - CNRS
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