From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752826AbXCUNbU (ORCPT ); Wed, 21 Mar 2007 09:31:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752839AbXCUNbU (ORCPT ); Wed, 21 Mar 2007 09:31:20 -0400 Received: from minas.ics.muni.cz ([147.251.4.40]:34821 "EHLO minas.ics.muni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752826AbXCUNbT (ORCPT ); Wed, 21 Mar 2007 09:31:19 -0400 Message-ID: <4601339C.6010706@gmail.com> Date: Wed, 21 Mar 2007 14:31:08 +0100 From: Jiri Slaby User-Agent: Thunderbird 2.0b2 (X11/20070116) MIME-Version: 1.0 To: =?UTF-8?B?IlNUZW55YUsgKEJydW5vIEdvbnrDoWxleiki?= CC: Dmitry Torokhov , Anssi Hannula , johann deneux , Linux kernel mailing list , linux-input@atrey.karlin.mff.cuni.cz Subject: Re: FF layer restrictions [Was: [PATCH 1/1] Input: add sensable phantom driver] References: <2460126662758025813@fi.muni.cz> <4af2d03a0703130919nb4893b1ja9ec795dcf4bf53c@mail.gmail.com> <38b3b7c0703131450v2646e63fj2be4b9dda7f928c0@mail.gmail.com> <45F722CE.9000602@gmail.com> <45F82626.8000108@gmail.com> <45F83930.4060401@gmail.com> <8e4ff20a0703141147n4b690ab8g4cc8138d1ecc94e1@mail.gmail.com> <8e4ff20a0703141218r3add7923n74470b5e16f58c5c@mail.gmail.com> In-Reply-To: <8e4ff20a0703141218r3add7923n74470b5e16f58c5c@mail.gmail.com> X-Enigmail-Version: 0.95b Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Muni-Spam-TestIP: 147.251.48.3 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-3.0 (minas.ics.muni.cz [147.251.4.35]); Wed, 21 Mar 2007 14:31:16 +0100 (CET) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org STenyaK (Bruno González) napsal(a): > On 3/14/07, Dmitry Torokhov 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). So, the resolution is? Since I want no longer have out-of-kernel driver, I need to know how to implement the phantom driver -- merge it `as is', i.e. control through mmio or rewrite ff layer somehow, and in that case how? There seem to be only few possibilities: - new 3D effect, which will be problematic in any other future use, that may need more than 3 axis. no matter if torques or vector is passed -- depending on device and programmer (as I need to compute torques from forces in FP). Maybe struct with 2x 3 axis is OK - "raw" effect, which may contain more axis, but this is ugly in Anssi's eyes - something else? (did I forget something) thanks, -- http://www.fi.muni.cz/~xslaby/ Jiri Slaby faculty of informatics, masaryk university, brno, cz e-mail: jirislaby gmail com, gpg pubkey fingerprint: B674 9967 0407 CE62 ACC8 22A0 32CC 55C3 39D4 7A7E