Re: [eigen] Do we need geometry refactoring? |

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*To*: eigen@xxxxxxxxxxxxxxxxxxx*Subject*: Re: [eigen] Do we need geometry refactoring?*From*: Benoit Jacob <jacob.benoit.1@xxxxxxxxx>*Date*: Thu, 29 Jul 2010 09:23:27 -0400*Dkim-signature*: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type; bh=GOdbCxC743uj0KPuUsIzl5OU3SEFQ8q5Esm6MuW1FRg=; b=vNr6K/V2ORO/RBFpi0M23HHt7HJ2ie5VcVKwHoRNopj/orW0HZUMNxBaxrRIwiAPx6 hkeHOxaaq6ZnxAQPAkK9HlW5etfjns8rChFRX2L9nCJNeT3W8PdwKrFLFiAWxU6+GNn0 cWNJnzJJtNrFO29ZiVz9BefaKJkLhaMIyulmI=*Domainkey-signature*: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=ruORoKDlwkDTkf9w14PfCXR8FpoGAp3UjO3ZgBDuk19ahDQTCAsXdD9VOZP1sNEaa0 nIMmzsli9LbpQ3EAlA8ZIQ4YmA+/CnP/m0UQEIJGzKWCY4ZGkfdxQfat0hOaDA88BdTo eqdElSBc1qmKaJqA7GMMKGKgajxNYNQUXE8Fg=

2010/7/29 Hauke Heibel <hauke.heibel@xxxxxxxxxxxxxx>: > I forgot to comment on this before... > > On Thu, Jul 29, 2010 at 2:45 PM, Benoit Jacob <jacob.benoit.1@xxxxxxxxx> wrote: >>>> Ok, the question is actually whether we want Translation, Quaternion, >>>> etc. behave like Transformations? >> >> Translation and Quaternion are different beasts here. >> >> The reason for Transform to exist is to represent non-linear (i.e. >> affine/projective) transformations. > > Isn't it only the projective part that makes the whole thing > non-linear? It that were true, you have like 2/3rd of the cases being > linear ones. Linear (in this context) means f(ax+by) = af(x)+bf(y). (Equivalently it means "a matrix transformation without using any homogeneous coords".) That entails in particular f(0)=0. So translations are nonlinear, so isometries and general affine transforms are nonlinear , unless of course their translation component is 0. > >> Translation is indeed a special case of that. But a Quaternion of norm >> 1 represents a rotation which is linear, so there is no reason to >> bother about Transform here; instead we unify Quaternion with other >> rotations in RotationBase and we take care once and for all of the >> interplay of rotations with general Transformations. > > I was primarily thinking about adding methods > > ::matrix() (returns a homogenous matrix) > ::linear() (returns a pure matrix) > ::translation (same as ::matrix(), read only expression) What do you mean when you say that ::translation() is the same as ::matrix() ? I agree about having these method in all geometry classes for consistency although I wonder about their usefulness in the cases where they would be trivial (i.e. linear() in Translation). Benoit > > We already have toRotationMatrix() and again it was the different > naming that confused me. > > - Hauke > > >

**Follow-Ups**:**Re: [eigen] Do we need geometry refactoring?***From:*Hauke Heibel

**References**:**[eigen] Do we need geometry refactoring?***From:*Hauke Heibel

**Re: [eigen] Do we need geometry refactoring?***From:*Adolfo Rodríguez Tsouroukdissian

**Re: [eigen] Do we need geometry refactoring?***From:*Benoit Jacob

**Re: [eigen] Do we need geometry refactoring?***From:*Hauke Heibel

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