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28 Mar 2024 16:46:20 EDT (-0400)
  challenge: surface connecting cubic_splines (Message 11 to 17 of 17)  
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From: Stephen
Subject: Re: challenge: surface connecting cubic_splines
Date: 11 Aug 2018 17:04:05
Message: <5b6f4f45$1@news.povray.org>
On 11/08/2018 20:42, Bald Eagle wrote:
> Stephen <mca### [at] aolcom> wrote:
>> On 11/08/2018 18:16, Bald Eagle wrote:
>>> .... now I'm thinking about making a circular bicubic patch....   :D
> 
>> IIRC Moray could make circular (cylindrical) bicubic patches.
>> It might be worth downloading and having a look at.
> 
> I was speaking of circular, as in disc / disk - shaped.
> 

Oops!
Discworld - Ringworld, what's the difference? :)

> I think I have Moray on my other laptop - I used it to start modeling The Secret
> Passage scene.  :)
> 

I remember that. I liked it. :)

> But this is what I came up with - not a perfect circle, which is why I wanted to
> pursue the 3x3 patch to have more exactly-specified corner points.

Not bad at all. :D


> Trying to
> reverse-interpolate where a point will be based on the control points....
> bleh.
> 
> 

<Walks away whistling.>

-- 

Regards
     Stephen


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From: Stephen
Subject: Re: challenge: surface connecting cubic_splines
Date: 11 Aug 2018 17:38:40
Message: <5b6f5760$1@news.povray.org>
On 11/08/2018 22:04, Stephen wrote:
>> But this is what I came up with - not a perfect circle, which is why I 
>> wanted to
>> pursue the 3x3 patch to have more exactly-specified corner points.
> 
> Not bad at all. :D

Thoughts!

I've found that when working with bezier patches. I have to tune them by 
eye.
How about bringing in the outliers in a tad through the radial?


-- 

Regards
     Stephen


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From: Bald Eagle
Subject: Re: challenge: surface connecting cubic_splines
Date: 11 Aug 2018 21:15:01
Message: <web.5b6f893ae21a6a89458c7afe0@news.povray.org>
Stephen <mca### [at] aolcom> wrote:

> > Not bad at all. :D

Thanks :)  My initial guesses on how to do this turned out to be very close.
Closer than I expected.

> Thoughts!
>
> I've found that when working with bezier patches. I have to tune them by
> eye.
> How about bringing in the outliers in a tad through the radial?


I used a torus to guide me, and had to introduce a number of fudge factors in my
control point matrix.  Crap that will look like heiroglyphics to me if I ever
open the file a month from now   ;)
Maybe I'll add some comments ... tomorrow.   :D

But here it is - as close as I bother making it, and the grid of control points
to show how --- uncircular, and unintuitive that is.

These Coons patches are beginning to look much more interesting...


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Attachments:
Download 'bicubicdisc.png' (185 KB)

Preview of image 'bicubicdisc.png'
bicubicdisc.png


 

From: Bald Eagle
Subject: Re: challenge: surface connecting cubic_splines
Date: 11 Aug 2018 21:40:01
Message: <web.5b6f8f3be21a6a89458c7afe0@news.povray.org>
Raising the internal 4 control points gives a Y-paraboloid, and then I inverted
the right two, and got this.

I kinda want to 3D print it and use it as an ice cream spoon.


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Attachments:
Download 'bicubicdisc.png' (195 KB)

Preview of image 'bicubicdisc.png'
bicubicdisc.png


 

From: Stephen
Subject: Re: challenge: surface connecting cubic_splines
Date: 16 Aug 2018 07:03:05
Message: <5b7559e9$1@news.povray.org>
On 12/08/2018 02:36, Bald Eagle wrote:
> Raising the internal 4 control points gives a Y-paraboloid, and then I inverted
> the right two, and got this.
> 
> I kinda want to 3D print it and use it as an ice cream spoon.
> 
> 
> 
> Raising the internal 4 control points gives a Y-paraboloid, and then I inverted
> the right two, and got this.
> 
> I kinda want to 3D print it and use it as an ice cream spoon.
> 


These shapes are so attractive.
I would use it as part of a wind chime, made of crystal glass.


-- 

Regards
     Stephen


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From: Le Forgeron
Subject: Re: challenge: surface connecting cubic_splines
Date: 17 Aug 2018 12:39:04
Message: <5b76fa28@news.povray.org>
Using a rational bezier patch (well, no need for the rational part here,
all the same weight everywhere)

Rendered with hgpovray38 (for the bezier patch and grid camera)


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Attachments:
Download 'hull.pov.txt' (4 KB) Download 'hull0.png' (357 KB) Download 'hull5.png' (390 KB)

Preview of image 'hull0.png'
hull0.png

Preview of image 'hull5.png'
hull5.png


 

From: Le Forgeron
Subject: Re: challenge: surface connecting cubic_splines
Date: 30 Aug 2018 14:22:15
Message: <5b8835d7$1@news.povray.org>
And in a country far far away, someone would have a look at
meshmaker.inc and the Coons macro !

It is there, in all its glory, just waiting to be seen.


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