Messages in this thread | | | Date | Fri, 15 Nov 1996 22:34:51 +0100 | From | Alexandre Maret <> | Subject | Re: RFC: A generic pointer protocol |
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Keith Rohrer wrote: > > Alexandre Maret wrote: > > > > The config : > > name,min value,max value > > > > { > > {"x",0,6000}, > > {"y",0,4000}, > > {"pressure",0,15} > > } > > > > When the application (which has to be enhanced a bit) start > > up, it just look if there is a "pressure" field in the config. > > If yes, then the *application* will know that the 3rd field is > > the pressure field, and the the value can be between 0 and 15.
> The application needs to know which parts of the controller map to which > field anyway, right? So the protocol should define a standard for what > goes where; certain physical inputs may be represented in multiple > fields. Presumably for device-independence at the application level, > all ranged inputs would be scaled to the same thing. > > So, for example, if all the inputs were 32-bit unsigned integers (big, > but not too nasty for alphas), you'd have button-down be -1 (i.e. > 0xffffffff) and button-up be 0. Then apps checking for clicks could > just test for zero, while things which wanted pressure/velocity could > test the actual value.
okay for the 32-bit everywhere... but we still need to know the actual range used by the device. 0 is no pressure, 15 is 100% pressure. The application need to know the range, unless the driver returns something like 0x0fffffff for 50% pressure.
But I think that we must *NOT* standardize which axis goes where, because it would limit us to what is standardized. If you says X is field 1, Y is 2, Z is 3, pressure is 4... what will you do when there will be a 4th axis, like rotation ? You just can't forecast all the needed axis. Don't you agree ?
> You know, this is all starting to sound like a cross between a mouse > protocol and MIDI...
I don't know MIDI... but you make me think about something somewhat fun... test the power of unix (and the sound of linux) : cat /vmlinuz > /dev/midi ...
each kernel is a piece of art ;-)
alex
-- \\-----------------------------------------------------------\\ // Alexandre Maret -- Linux : The choice of a GNU generation // \\ amaret@infomaniak.ch -- http://www.infomaniak.ch/~amaret \\ //-----------------------------------------------------------//
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