[PD] GEM:discribe position of model with 2 points

[IOhannes m zmoelnig]

Falk Grieffenhagen.de wrote:
> 
> Hi list,
> 
> I currently have a little math problem:
> 
> I have a wavefront model (see below) which looks a bit like a stick. I 
> want to set the position by 2 points in 3D (beginning and end) instead 
> of one point,  rotation , and scale.
> Any help would be great!!
> 

i would do that in 2 steps:
#1: normalize your stick (set length to 1.0, align it to an axis)
#2: align the normalized stick to your 2 points

i demonstrated #1 in the attached patch. now the base of the stick is 
within the origin of the local coordinate system, while the tip is at 
(1/0/0).
now #2 should be fairly simple: [translate] the stick to 1 point and 
rotate/scale it so that the 2nd point matches the end of the stick. the 
procedure is in fact the reverse of #1 (but the reference points have 
changed)

mfg.adsr.
IOhannes