On 09/16/2016 04:08 AM, Le_Forgeron wrote:
> Le 16/09/2016 à 00:34, Jim Holsenback a écrit :
>> On 9/15/2016 12:59 PM, William F Pokorny wrote:
>>> On 09/15/2016 12:03 PM, Jim Holsenback wrote:
>>>
>>> Thanks. I've attempted some descriptive text at:
>>>
>>> http://wiki.povray.org/content/Reference_Talk:Lemon
>>
>> a combination of both: http://wiki.povray.org/content/Reference:Lemon
>>
>
> I really liked the passage about the american football and other real
> evocations. It gave flesh to the description.
>
>
>
> The constraint on minimal inner_radius is really a dangerous beast:
>
>
> If base & cap radius are both 0, the inner_radius must be at least half
> the distance between base and cap point (it would be a sphere)
>
> So, as stated, the doc is false.
>
>
> If base & cap radius are identical, the minimal inner_radius would be
> sqrt( radius² + (distance/2)² ) , where distance is the length between
> base and cap points.
>
> when base & cap radius are different, it become nightmare (the exact
> equation is in the code, if you dare to want to know it).
>

Argh. Sorry Jim. I got the wording for what I believe is the lower-most 
bound for the inner radius wrong. I had in my head only to offer general 
guidance there.

Adding the full equations is an option I guess - we do for other objects 
in the docs. If we stick with a general description, we could build on 
what you, Jérôme, wrote with perhaps:

If base & cap radius are both 0, the inner_radius must be at least half
the distance between base and cap point (it would be a sphere). 
Otherwise the minimum inner radius is larger than half the distance 
between base and cap point. Any time the inner radius given is too 
small, the code uses the minimum radius over the specified one and 
issues a warning.

Bill P.

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