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28 Mar 2024 18:06:35 EDT (-0400)
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From: Le Forgeron
Subject: Re: Wavefront OBJ import
Date: 15 Sep 2016 13:18:57
Message: <57dad801$1@news.povray.org>
Le 15/09/2016 à 18:59, William F Pokorny a écrit :
> On 09/15/2016 12:03 PM, Jim Holsenback wrote:
>> On 9/15/2016 7:13 AM, William F Pokorny wrote:
>>> FYI - A new object in the "lemon" is in the master branch and not yet
>>> documented in povray's documentation. Jérôme has some documentation for
>>> it already on his page at:
>>
>> it's been added http://wiki.povray.org/content/Reference:Lemon
>>
>> looks like the opening paragraph could use some help so I also created a
>> talk page as well: http://wiki.povray.org/content/Reference_Talk:Lemon
>>
> 
> Thanks. I've attempted some descriptive text at:
> 
> http://wiki.povray.org/content/Reference_Talk:Lemon
> 
> Bill P.

I like it, but the introducing description is a bit harsh for the
non-mathematically-addicted.
So I added a bit in the discussion too


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From: Jim Holsenback
Subject: Re: Wavefront OBJ import
Date: 15 Sep 2016 18:34:03
Message: <57db21db$1@news.povray.org>
On 9/15/2016 12:59 PM, William F Pokorny wrote:
> On 09/15/2016 12:03 PM, Jim Holsenback wrote:
>> On 9/15/2016 7:13 AM, William F Pokorny wrote:
>>> FYI - A new object in the "lemon" is in the master branch and not yet
>>> documented in povray's documentation. Jérôme has some documentation for
>>> it already on his page at:
>>
>> it's been added http://wiki.povray.org/content/Reference:Lemon
>>
>> looks like the opening paragraph could use some help so I also created a
>> talk page as well: http://wiki.povray.org/content/Reference_Talk:Lemon
>>
>
> 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


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From: Le Forgeron
Subject: Re: Wavefront OBJ import
Date: 16 Sep 2016 04:08:40
Message: <57dba888$1@news.povray.org>
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:
>>> On 9/15/2016 7:13 AM, William F Pokorny wrote:
>>>> FYI - A new object in the "lemon" is in the master branch and not yet
>>>> documented in povray's documentation. Jérôme has some documentation for
>>>> it already on his page at:
>>>
>>> it's been added http://wiki.povray.org/content/Reference:Lemon
>>>
>>> looks like the opening paragraph could use some help so I also created a
>>> talk page as well: http://wiki.povray.org/content/Reference_Talk:Lemon
>>>
>>
>> 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).


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From: Jim Holsenback
Subject: Re: Wavefront OBJ import
Date: 16 Sep 2016 08:53:23
Message: <57dbeb43$1@news.povray.org>
On 9/16/2016 4:08 AM, Le_Forgeron wrote:
> 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).

no worries /but/ i wish you'd been as verbose with your previous post 
... however i see a bit of a conflict (perhaps i've characterized 
incorrectly) item 4 and 5 seem a bit murky or are the /both/ correct:

http://wiki.povray.org/content/Reference:Lemon


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From: William F Pokorny
Subject: Re: Wavefront OBJ import
Date: 16 Sep 2016 09:33:21
Message: <57dbf4a1@news.povray.org>
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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From: William F Pokorny
Subject: Re: Wavefront OBJ import
Date: 16 Sep 2016 09:49:12
Message: <57dbf858$1@news.povray.org>
On 09/16/2016 08:53 AM, Jim Holsenback wrote:
> On 9/16/2016 4:08 AM, Le_Forgeron wrote:
>> 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).
>
> no worries /but/ i wish you'd been as verbose with your previous post
> ... however i see a bit of a conflict (perhaps i've characterized
> incorrectly) item 4 and 5 seem a bit murky or are the /both/ correct:
>
> http://wiki.povray.org/content/Reference:Lemon
>
>

I believe we need to delete the following list item (me originally 
leading you wrong I think):

* generally speaking Inner_Radius must be greater than or equal to the 
distance between end points

or change it to:

* generally speaking the Inner_Radius must be greater than or equal to 
half the distance between end points

Bill P.


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From: Jim Holsenback
Subject: Re: Wavefront OBJ import
Date: 16 Sep 2016 10:41:14
Message: <57dc048a$1@news.povray.org>
On 9/16/2016 9:33 AM, William F Pokorny wrote:
> 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.

like i said ... no worries

>
> 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:

sticking with general description

>
> 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.

i /think/ i've got it this time: 
http://wiki.povray.org/content/Reference:Lemon


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From: Le Forgeron
Subject: Re: Wavefront OBJ import
Date: 16 Sep 2016 12:05:09
Message: <57dc1835$1@news.povray.org>
Le 16/09/2016 à 16:41, Jim Holsenback a écrit :
> On 9/16/2016 9:33 AM, William F Pokorny wrote:
>> 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.
> 
> like i said ... no worries
> 
>>
>> 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:
> 
> sticking with general description
> 
>>
>> 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.
> 
> i /think/ i've got it this time:
> http://wiki.povray.org/content/Reference:Lemon
> 

I added yet another comment in the discussion.


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From: Jim Holsenback
Subject: Re: Wavefront OBJ import
Date: 17 Sep 2016 08:57:10
Message: <57dd3da6$1@news.povray.org>
On 9/16/2016 12:05 PM, Le_Forgeron wrote:
> I added yet another comment in the discussion.

http://wiki.povray.org/content/Reference:Lemon


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From: William F Pokorny
Subject: Re: Wavefront OBJ import
Date: 17 Sep 2016 09:52:39
Message: <57dd4aa7$1@news.povray.org>
On 09/17/2016 08:57 AM, Jim Holsenback wrote:
> On 9/16/2016 12:05 PM, Le_Forgeron wrote:
>> I added yet another comment in the discussion.
>
> http://wiki.povray.org/content/Reference:Lemon
>
>

Suggesting a correction and further tweak at bottom of the page:

http://wiki.povray.org/content/Reference_Talk:Lemon

Bill P.


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