"bublible" <nomail@nomail> wrote:
> clipka <ano### [at] anonymousorg> wrote:
> > Am 16.03.2015 um 22:06 schrieb bublible:
> > > clipka <ano### [at] anonymousorg> wrote:
> > >> Am 16.03.2015 um 20:39 schrieb bublible:
> > >>> Is there a way to find out/obtain/get object's "rotation matrix" so it can be
> > >>> applied to another object?
> > >>
> > >> Nope, sorry. You'd need to modify POV-Ray's source code for that stunt.
> > >> (And, knowing that you're wrestling with LDD-to-POVRay, that won't get
> > >> you anywhere either because the tool is designed in such a way that
> > >> scenes won't render with an unofficial version of POV-Ray. Did I mention
> > >> before that the tool sucks big time?)
> > >
> > > yea you did mention it but it didn't help me much in solving my problem so I did
> > > not care to reply, sorry :D
> >
> > Even if you had replied, I'd have happily taken the opportunity to again
> > point out what I think of the LDD-to-POVRay tool ;)
> >
> > > anyway, there have to be some way as I have here one script dealing with
> > > automatic rotation of background (ehm, actually a box functioning as background)
> > > that expands and face directly to camera nevermind cameras position which is
> > > basically what I want but I want just one axis to be corresponding to the camera
> > > axis in oposite angle as my polygon is rotate<0,0,0> and I want it turns to
> > > directly to camera but only on its y axis (I got gradient polygon functioning as
> > > a base plane and I need its gradient would always go from camera to the distance
> > > far away independently of LDD/camera rotation)
> >
> > If you can get that far from whatever parameters there are floating
> > around in the scene, then here's what I'd do:
> >
> > (1) Transform a unit vector (x or z, depending on the original
> > orientation of the model) according to the rotation matrix, using the
> > vtransform() function.
> >
> > (2) Take the resulting vector, and multiply it by <1,0,1>.
> >
> > (3) If needed, normalize the resulting vector using vnormalize().
> >
> > => Voila, you should now have rotated the original vector around the y axis.
> >
> > If what you need is a rotation rather than a rotated vector, continue as
> > follows:
> >
> > (4) Compute the cosine of the angle between the (normalized) rotated
> > vector and the original vector by computing the dot product, using the
> > dot() function.
> >
> > (5) From the cosine of the angle, compute the angle in radians using the
> > acos() function.
> >
> > (6) If needed, compute the angle in degrees by multiplying with 180/pi.
> >
> > (7) If you find that the rotation doesn't fit, try inverting the sign.
> >
> > I hope this helps.
>
>
> :-D looks like you really know what you are talking about much more than I am
> able to understand fully at this point, I'm afraid...
>
> So could you elaborate more on this, or even better if it doesn't bother you
> much: could you provide some fictional example here (you know, I would just
> replace corresponding values in it in my script)?
>
> BTW aren't you on Eurobricks.com (if so I would include you in credit for the
> help woth the script as I will post it there including complete tutorial)? I am
> asking cos this povray forum format is so
> limiting and I would like to write to you about this in more usable way :(

Well, I got it and maybe strangely enough the help came from guy called hrontos
- developer of your hated LDD-to-POVRay :):):):):)

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