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

[Remo Pini]

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