POV-Ray : Newsgroups : povray.general : Prism Bezier spline to natural spline conversion Server Time
4 Nov 2024 19:16:20 EST (-0500)
  Prism Bezier spline to natural spline conversion (Message 1 to 3 of 3)  
From: leroy
Subject: Prism Bezier spline to natural spline conversion
Date: 31 Jul 2008 23:30:52
Message: <4892A035.8040503@joplin.com>
Rune got me going over my old rounded prism macros. What I'd like to do 
is make a macro that'll round the corners of any prism type. The main 
Idea is to use the Spline function to adjust data points. The trouble is 
that prism uses the Bezier_Spline and Splines use the Natural_Spline.
Does anybody know how to do conversion between the two?
        (If there is a conversion )


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From: Blue Herring
Subject: Re: Prism Bezier spline to natural spline conversion
Date: 1 Aug 2008 08:58:48
Message: <48930888$1@news.povray.org>
leroy wrote:
> Rune got me going over my old rounded prism macros. What I'd like to do 
> is make a macro that'll round the corners of any prism type. The main 
> Idea is to use the Spline function to adjust data points. The trouble is 
> that prism uses the Bezier_Spline and Splines use the Natural_Spline.
> Does anybody know how to do conversion between the two?
>        (If there is a conversion )

If it helps, the PointArrays macros in the object collection has a 
number of macros dealing with bezier splines.  It doesn't have a natural 
  to bezier converter currently (perhaps that would be good for the next 
version) but it can convert linear splines in various ways to bezier 
ones.  It also has some macros to simulate a bezier spline object, so 
perhaps you wouldn't need to use naturals.  I'm pretty sure its not 
possible to convert bezier -> natural for all cases, as the natural is 
not capable of representing some of the things a bezier can do.

http://lib.povray.org/searchcollection/index2.php?objectName=PointArrays&version=1.1.1&contributorTag=Blue%20Herring

(Don't mean to keep plugging...)

I've made a number of rounded prism macros as well, all failures to one 
degree or another.   Might give it a try again sometime though.  Makes 
me wonder if its the cold fusion of the POV-Ray world :)

-- 
-The Mildly Infamous Blue Herring


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From: Leroy Whetstone
Subject: Re: Prism Bezier spline to natural spline conversion
Date: 1 Aug 2008 23:42:09
Message: <4893F457.3040704@joplin.com>
Blue Herring wrote:
> 
>
http://lib.povray.org/searchcollection/index2.php?objectName=PointArrays&version=1.1.1&contributorTag=Blue%20Herring

 >
That helped, a little. I've wrote my own bezier spline in c++ awhile 
back, for a prism/polygon editor at: http://leroywhetstone.s5.com
Now, I need to get a handle on the natural spline.

> 
> I've made a number of rounded prism macros as well, all failures to one 
> degree or another.   Might give it a try again sometime though.  


>Makes me wonder if its the cold fusion of the POV-Ray world :)

Ain't it the truth! I think some of the difficulties lay in that there are
different spline options with prism & sphere_sweep objects and the 
spline function.


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