[PD] GEM: "up" parameter in view message

[Piotr Majdak]

Hi!

IOhannes m zmoelnig wrote:

> well, the "up" vector shows you what is "up" in the view.
> 
> imagine you have the camera at 0,0,0 and an object at 1,0,0
> if you want to rotate the camera along the (1,0,0) axis, you have to
> define where the up-direction is (there is no such thing as gravity in
> Gem-space)
> 
> if you turn your head by 90° around your nose-axis, your up-vector will
> turn from (0,1,0) to (1,0,0)
> 
> i hope this is clear (it is rather simple, but i don't know how to
> explain it well)

thanks, your explanation is very clear. I wondered what happens setting 
the "up" vector to (0,0,1) in your example above. Generally, this should 
interfere with "target" and "view" vectors. But it doesn't - I think 
that only the "up" components, which are in the plane normal to the line 
defined by "view" and "target", are taken into account. The component 
parallel to the [view,target]-line seems to be ignored (what, of course, 
makes sense). Do you agree?

Thanks,

Piotr