[Bf-committers] OT: 3D-Math Question

joe joeedh at gmail.com
Thu May 7 22:26:47 CEST 2009


in general it's better to ask such questions on #blendercoders at
irc://irc.freenode.net

Joe

On Thu, May 7, 2009 at 11:04 AM, Remo Pini <remo.pini at avexys.com> wrote:
> Hi all
>
>
>
> I know this might be the wrong place to ask, but with so many brilliant
> heads in one spot, I just have to try...
>
>
>
> I have an object A and an object B
>
>
>
> For each of these objects, I have a translation/location T
> (3D-Vector/Vertex), a rotation R (Quaternion) and a Scale S (Float).
>
>
>
> So:
>
> Object A: Ta, Ra, Sa
>
> Object B: Tb, Rb, Sb
>
>
>
> My problem is the following: Object B's T & R are relative to Object A
> and I need to transform them into absolute T & R so that I can calculate
> the actual position of each vertex.
>
>
>
> I tried some (I thought) obvious things like:
>
>
>
> Tb' = (Tb-Ta)*Ra+Ta
>
> Rb' = Ra*Rb
>
>
>
> Then for each Vertex Vb of B:
>
>
>
> Vb' = (Vb*Sb)*Rb + Tb
>
>
>
> However, this seems to be wrong, if I start to rotate Object A around,
> the position of Object B relative to Object A changes (which it
> shouldn't).
>
>
>
> What am I doing wrong here?
>
>
>
> Cheer
>
>
>
> Remo
>
>
>
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