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Am 07.10.2016 um 21:18 schrieb omniverse:
> "omniverse" <omn### [at] charter net> wrote:
>> After reading about this at:
>>
>>
http://news.povray.org/povray.documentation.inbuilt/message/%3Cweb.57f3be98a39309ab21263ef70%40news.povray.org%3E/#%3
> Cw
>> eb.57f3be98a39309ab21263ef70%40news.povray.org%3E
>>
>> I had to get another look for myself at what happens when changing viewpoint for
>> +z. Found the x and y rotations appear opposite, yet z remains counterclockwise
>> when seen from these different directions and with the change to x sign.
>>
>> First is the usual view for many POV-Ray scenes with camera at a -z coordinate,
>> looking toward +z. The default 'up' +y and 'right' +x (or <4/3,0,0>).
>
> Second is with negative 'right', or right <-4/3,0,0>, and 'up' still positive y.
The reason why rotation about Z /appears/ to remain the same is that
from the camera's point of view it /appears/ like you've achieved the
change in handedness (which flips all rotations) by flipping the Z axis
(which additionally flips the rotation around the Z axis); so
effectively you've flipped the apparent rotation about the X and Y axes
once, and the rotation about the Z axis twice making it the only
rotation that appears unchanged.
If you chose the opposite camera perspective for the 2nd video, you
could achieve that the Y and Z axes appear to remain the same and the X
axis appears to be flipped; in that case, the rotation about the Y and Z
axes would appear to be flipped, and the rotation about the X axis would
appear to remain unaffected.
Likewise, you should also be able to make it appear as if rotation about
the Y axis remained unaffected but the other two flipped, or to make
rotation about all three axes to appear flipped.
I haven't thought it through entirely yet, but I suspect it is
impossible to flip the handedness while making rotations about an odd
number of axes appear unaffected.
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