Re: [Plib-devel] Re: control abstraction, continued (ad infinitum)

[Steve B. <sjb...@ai...>]

James Turner wrote:
> 
> Some more points that have come up:
> 
> the need for controls with both analog inputs and digital buttons. Hence
> I have a new input type, ctlDual, which clan be used as follows:
> 
> ctlDual *t = new ctlDual("Throttle", 0.1, 0.05, CTL_JS_0, 3);
>         2 parameter is the 'step size', explained below
>         3 param is a threshold, also explained below

Why should there be a new type?   I think that all analog inputs
should have the capability of being driven from digital inputs
because some people don't like using the mouse or joystick at
all. (eg Quake fanatics)

> then:
> 
> t->addDigital(new ctlDigital("100% Throttle", CTL_KEYBOARD, '#'),
> CTL_DUAL_MAX);
> t->addDigital(new ctlDigital("Increase Throttle", CTL_KEYBOARD, '+'),
> CTL_DUAL_INC);

I don't think this should be under program control.  I think the application
should just state it's needs:

  addDigital ( "RetractSwitch" ) ;
  addAnalog  ( "Throttle" ) ;

...and have an external file (say '.fgfs_controls' for FlightGear,
'.tux_aqfh_controls' for Tux, etc) that binds physical controllers
to each application variable:

RetractSwitch:DIGITAL:  'R'==1, 'U'==0
Throttle:ANALOG:  MOUSE_NORTH_SOUTH + MOUSE_MIDDLE_BUTTON, scale=1.5,
                  deadzone=0.3, linear
Flaps:ANALOG: '<'==++0.1, '>'==--0.1

...and so on.  Then (initially) we can create such a file that installs
with FGFS (or whatever) which has the default controllers - possibly
one file for people with joysticks and one without.  Experts can then
hand-edit that file to set their own personal preferences - and perhaps
some kind person would create a GUI-driven configuration widget that
would be application-independent.

> One other suggested change is that digital inputs drive callbacks rather
> than being polled; this makes a lot of sense I suspect, so I will add a
> setCallback method and alternate constructor to ctlDigital. I don't
> think callback behaviour makes sense for analog inputs, but if people
> disagree then it could be included.

It should be possible to use three mechanisms:

1) Polling (that doesn't work well with GLUT - but it can be done)
2) Callbacks.
3) Direct variable drive (ie you call a single 'update' function and
   it updates a bunch of variables that the application bound to the
   controllers).

Each method has its benefits.
 
> As ever feedback is appreciated especially from non-FG users of PLIB,
> who I suspect are all looking on in amazement and thinking 'when would I
> *ever* use this junk' :-)

To the contrary - I'm hoping that this will allow me to get mouse and
keyboard drivers for my two Tux games (A Quest for Herring - and the
upcoming 'TuxKart') - with zero effort on my part!
 
-- 
Steve Baker                  http://web2.airmail.net/sjbaker1
sjb...@ai... (home)  http://www.woodsoup.org/~sbaker
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