From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753362AbXCOUvK (ORCPT ); Thu, 15 Mar 2007 16:51:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753364AbXCOUvK (ORCPT ); Thu, 15 Mar 2007 16:51:10 -0400 Received: from wr-out-0506.google.com ([64.233.184.231]:60423 "EHLO wr-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753362AbXCOUvI convert rfc822-to-8bit (ORCPT ); Thu, 15 Mar 2007 16:51:08 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=uJ1O3UHdcf5osRMFg3CjsX8wE01dSZPx/KOu7XauGJRpKC7o5XwnuyN8GYGq2c1yy4J+daI0yc1PMsAJW2I8g6BOP2XCCSlCq9AESIxmN8l02M/ZuYA7vRe1HK7b1Q7DjaOcmxsCVhk17WJ7M057feG+OKRwad6YCmjgRvxe1dU= Message-ID: <38b3b7c0703151351i23d42d67n1d7469fd14e433e2@mail.gmail.com> Date: Thu, 15 Mar 2007 21:51:07 +0100 From: "johann deneux" To: "=?ISO-8859-1?Q?STenyaK_(Bruno_Gonz=E1lez)?=" Subject: Re: FF layer restrictions [Was: [PATCH 1/1] Input: add sensable phantom driver] Cc: "Dmitry Torokhov" , "Anssi Hannula" , "Jiri Slaby" , "Linux kernel mailing list" , linux-input@atrey.karlin.mff.cuni.cz In-Reply-To: <8e4ff20a0703141218r3add7923n74470b5e16f58c5c@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8BIT Content-Disposition: inline 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> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On 3/14/07, STenyaK (Bruno González) wrote: > 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. > I would think one plane and one axis is all that's needed for a 3d vector, or? Do we understand eachother? > 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). Same remark here. A torque is a 3-dimensional thing, just like a force. What for do you need 4 components? -- Johann