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Date: Wed, 14 Mar 2007 20:18:54 +0100
From: "=?ISO-8859-1?Q?STenyaK_(Bruno_Gonz=E1lez)?=" <stenyak@gmail.com>
To: "Dmitry Torokhov" <dmitry.torokhov@gmail.com>
Subject: Re: FF layer restrictions [Was: [PATCH 1/1] Input: add sensable phantom driver]
Cc: "Anssi Hannula" <anssi.hannula@gmail.com>,
       "Jiri Slaby" <jirislaby@gmail.com>,
       "johann deneux" <johann.deneux@gmail.com>,
       "Linux kernel mailing list" <linux-kernel@vger.kernel.org>,
       linux-input@atrey.karlin.mff.cuni.cz
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On 3/14/07, Dmitry Torokhov <dmitry.torokhov@gmail.com> wrote:
> > I have a question: if the force is to be 3D, why only 3 possible values?
> > What would they be, 3 torques or 3 forces? In the case of car sims (ff
> > steering wheels), only one axis of torque is usually used (except for 6 dof
> > platforms, as mentioned).
> >
>
> I wonder if we could somehow extend or augment FF envelope se we could
> specify a plane for the effect.. Then a vector could be represented by
> a sum 3 constant effects in 3 separate planes and we could also use
> spring and other effects as well.

Ideally, afaik we should use:
-3 values for translation force (linear force): x,y,z components of
the force vector.
-4 values for rotation force (torque): x,y,z,w components of the
quaternion. You can also use euler angles (and i think there are
another one or two notations), which is just 3 values, but i'm not
sure it will be a correct decision (due to the gimbal lock problem,
which may or may not be present in ff devices, dunno).

-- 
Saludos,
     STenyaK

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