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22 Dec 2024 18:17:03 EST (-0500)
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From: Mike Horvath
Subject: Parametric surfaces with three parameters?
Date: 13 Aug 2018 22:41:39
Message: <5b724163$1@news.povray.org>
Is there a list somewhere of parametric surfaces that take three 
parameters? I haven't put a lot of thought into it, but spheres, 
cylinders and cones work. Thanks.


Mike


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From: Mike Horvath
Subject: Re: Parametric surfaces with three parameters?
Date: 13 Aug 2018 22:42:26
Message: <5b724192$1@news.povray.org>
On 8/13/2018 10:41 PM, Mike Horvath wrote:
> Is there a list somewhere of parametric surfaces that take three 
> parameters? I haven't put a lot of thought into it, but spheres, 
> cylinders and cones work. Thanks.
> 
> 
> Mike


Er, I mean solids, not surfaces.


Mike


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From: dick balaska
Subject: Re: Parametric surfaces with three parameters?
Date: 13 Aug 2018 23:03:27
Message: <5b72467f$1@news.povray.org>
On 08/13/2018 10:41 PM, Mike Horvath wrote:
> Is there a list somewhere of parametric surfaces, er solids, 


It seems to me that a math question would have a more appropriate place
than p.off-topic.


-- 
dik
Rendered 344576 of 345600 pixels (99%)


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From: Mike Horvath
Subject: Re: Parametric surfaces with three parameters?
Date: 14 Aug 2018 03:23:31
Message: <5b728373$1@news.povray.org>
On 8/13/2018 11:03 PM, dick balaska wrote:
> On 08/13/2018 10:41 PM, Mike Horvath wrote:
>> Is there a list somewhere of parametric surfaces, er solids,
> 
> 
> It seems to me that a math question would have a more appropriate place
> than p.off-topic.
> 
> 

If I could go back in time I would choose a different group.


Mike


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From: Mike Horvath
Subject: Re: Parametric surfaces with three parameters?
Date: 14 Aug 2018 03:23:57
Message: <5b72838d$1@news.povray.org>
On 8/14/2018 3:23 AM, Mike Horvath wrote:
> On 8/13/2018 11:03 PM, dick balaska wrote:
>> On 08/13/2018 10:41 PM, Mike Horvath wrote:
>>> Is there a list somewhere of parametric surfaces, er solids,
>>
>>
>> It seems to me that a math question would have a more appropriate place
>> than p.off-topic.
>>
>>
> 
> If I could go back in time I would choose a different group.
> 
> 
> Mike


Forgot to add a smiley.


:)


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From: Stephen
Subject: Re: Parametric surfaces with three parameters?
Date: 14 Aug 2018 04:20:33
Message: <5b7290d1$1@news.povray.org>
On 14/08/2018 08:23, Mike Horvath wrote:
> On 8/13/2018 11:03 PM, dick balaska wrote:
>> On 08/13/2018 10:41 PM, Mike Horvath wrote:
>>> Is there a list somewhere of parametric surfaces, er solids,
>>
>>
>> It seems to me that a math question would have a more appropriate place
>> than p.off-topic.
>>
>>
> 
> If I could go back in time I would choose a different group.
> 
> 
> Mike


Since it is OT

If I could go back in time I would choose a different life.  ;)


-- 

Regards
     Stephen


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From: dick balaska
Subject: Re: Parametric surfaces with three parameters?
Date: 14 Aug 2018 04:45:02
Message: <5b72968e$1@news.povray.org>
On 08/14/2018 04:20 AM, Stephen wrote:
> On 14/08/2018 08:23, Mike Horvath wrote:
>> On 8/13/2018 11:03 PM, dick balaska wrote:
>>> On 08/13/2018 10:41 PM, Mike Horvath wrote:
>>>> Is there a list somewhere of parametric surfaces, er solids,
>>>
>>>
>>> It seems to me that a math question would have a more appropriate place
>>> than p.off-topic.
>>>
>>>
>>
>> If I could go back in time I would choose a different group.
>>
>>
>> Mike
> 
> 
> Since it is OT
> 
> If I could go back in time I would choose a different life.  ;)

I would choose to avoid the million dollar divorce (which was more money
than I had).


-- 
dik
Rendered 344576 of 345600 pixels (99%)


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From: Bald Eagle
Subject: Re: Parametric surfaces with three parameters?
Date: 14 Aug 2018 08:25:01
Message: <web.5b72c95d5535509dc437ac910@news.povray.org>
Mike Horvath <mik### [at] gmailcom> wrote:
> On 8/13/2018 10:41 PM, Mike Horvath wrote:
> > Is there a list somewhere of parametric surfaces that take three
> > parameters?

> Er, I mean solids, not surfaces.


I toyed with this a while back:
http://news.povray.org/povray.advanced-users/thread/%3Cweb.579fc21ee9f788f45e7df57c0@news.povray.org%3E/

Any parametric surface would become a parametric solid, given a variable third
parameter, since - using the sphere for example, you'd have the r value of the
radius.
Varying the radius from 0 to unity would give you a solid sphere.

But "solids" in POV-Ray are really only surfaces with insides and outsides,
aren't they...?


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From: clipka
Subject: Re: Parametric surfaces with three parameters?
Date: 14 Aug 2018 17:22:22
Message: <5b73480e$1@news.povray.org>
Am 14.08.2018 um 14:21 schrieb Bald Eagle:
> Mike Horvath <mik### [at] gmailcom> wrote:
>> On 8/13/2018 10:41 PM, Mike Horvath wrote:
>>> Is there a list somewhere of parametric surfaces that take three
>>> parameters?
> 
>> Er, I mean solids, not surfaces.
> 
> 
> I toyed with this a while back:
>
http://news.povray.org/povray.advanced-users/thread/%3Cweb.579fc21ee9f788f45e7df57c0@news.povray.org%3E/
> 
> Any parametric surface would become a parametric solid, given a variable third
> parameter, since - using the sphere for example, you'd have the r value of the
> radius.
> Varying the radius from 0 to unity would give you a solid sphere.
> 
> But "solids" in POV-Ray are really only surfaces with insides and outsides,
> aren't they...?

Technically, "solids" in POV-Ray are objects with...

(1a) a well-defined surface,
(1b) an algorithm to compute the intersection points between a ray and
said surface, as well as the surface normals at those points

(2a) a well-defined volume,
(2b) an algorithm to compute whether a given point in 3D space is inside
said volume

3-parametric solids would generally satisfy (1a) and (2a) (except in
pathological cases), but for the general case I guess (1b) and (2b)
would effectively boil down to generating an approximate mesh representaion.


If the 3-parametric equation does not "fold back" into itself, the
surface of the solid can also be modeled using six 2-parametric surfaces.


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