Le 26/05/2016 00:53, Jim Holsenback a écrit :
> On 5/24/2016 9:32 AM, William F Pokorny wrote:
>> Would someone who knows what they are doing wiki-wise - or who has the
>> "create" authority for the reference->object->lathe/prism sections can
>> create the talk/discussion area. Or, I suppose, if the update looks good
>> to those reviewing, just get it into the actual reference.
> 
> lathe additions have been added: http://wiki.povray.org/content/Reference:Lathe
> 
> didn't have time to do prism yet
> 

Thanks for your time :-)

I'm going to be painful, hopefully not to much for Jim, but other(s):

what is "clockwise" and "counterClockwise" ?

And before someone jumps in to state the obvious, think again about it.




Usually (Danger Will Robinson, Danger), +X is to the right and +Y is up.

And the direction of Z when going 3D is a holy war between left-hand and right-hand
system.


But it is not unusual either that +X is to the right and +Y is down (many pictures
format have such convention).
(origin at top left, and in fact, western-text has that same convention: Nth lines,
Mth character on that line)


And some tenants of right-hand system like +X to the left, +Y up and +Z away (and most
3D formats are rather right-handed... at least STL is strongly thought as such)



I also want to stress that it is topologically, and logically too, impossible to
define left/right with an alien over a radio link: even using physical laws to have
the same experiment. You can define down and up (gravity is helpful), you can define
away and nearer, but,
as the alien's environment might be matter or anti-matter, you cannot use anything to
provide the same definition of left & right.
And if you cannot define left/right, clockwise and counterclockwise are lost too.


All this, to ask for more explanation, or illustration, of "clockwise" and
"counterClockwise".

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