POV-Ray : Newsgroups : povray.documentation.inbuilt : Orientation and left handed frame : Orientation and left handed frame Server Time
28 Jan 2022 10:57:02 EST (-0500)
  Orientation and left handed frame  
From: lelama
Date: 4 Oct 2016 10:50:01
Message: <web.57f3be98a39309ab21263ef70@news.povray.org>
The documentation of povray seems to me inacurate on the oritentation
considerations if I look at http://www.povray.org/documentation/view/3.7.0/15/

To fix the orientattion conventions, there are 2 choices to be done :
- does xyz follow the left or right handed convention ?
- do we screw or unscrew the rotations with a positive angle ?

These two choices may be done independently. The documentation suggests that
these two choices are dependent, making the doc difficult to read. In my
opinion, the correct formulation should be that :

By default:
- xyz follows the left handed convention
- rotations with a positive angle with respect to a vector unscrews if the eye
is in the direction of the vector.
If we change the camera right vector to change to the right handed convention,
povray will implicitly change automatically change the second convention and
will screw positive rotations.

To produce povray code from an  other software that cooperates with povray,
sometimes the other software does not follow the same conventions. In this case,
the documentation is not sufficient and it is necessary to experiment to reelly
understand what's going on.

My 2 cents,
Laurent.


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